STRUCTURAL MONITORING

Page Page
INDEX INDEX
No. No.

Instrumentation Introduction 1-2 Soil Extensometer 36

Casagrande Piezometer 3-4 Pressure Cell (V.W) 37-39

Uplift Pressure Measuring System 5 Jackout Pressure Cell (V.W) 40

Twin Tube Hydraulic Piezometer 6-8 Temperature Gauge (V.W) 41

Simulator for Twin Tube Piezometer System9 Borehole Stress Meter (V.W) 42-43

Pneumatic Piezometer 10-11 Joint Meter (V.W) 44

Piezometer (V.W) 12-13 Triaxial Joint Meter (V.W) 45

Cross Arm Settlement System 14-15 Reinforcement Load Gauge (V.W) 46

Base Plate Settlement System 16 Strain Gauge Embedment Type (V.W) 47-48

Settlement Points 16 Strain Gauge Surface Mounted Type (V.W) 48

Magnetic Settlement System 17-18 Centre Hole Load Cell (V.W) 49-50

Liquid Settlement Cell (V.W) 19 Instrumented Rock Bolt 51

Digital Inclinometer Systems 20-22 Pullout Test Apparatus 52-53

Tiltmeter (V.W) 23-24 Automatic Water Level Recorder (V.W) 54-55

Hanging Pendulum 25-26 Water Leakage Measuring System (V.W) 56

Inverted Pendulum 27-28 Read Out Unit 58

Automatic Pendulum Co-ordinator 29 Data Acquisition System (Data Logger) 59-60

Borehole Extensometer (V.W) 30-33 Advanced Technology & Engineering 61-67

Services (Consultancy Division)
Tape Extensometer 34-35

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 STRUCTURAL MONITORING

safety of structure and protect the public.

WHY INSTRUMENTATION
Instrumentation must be carefully selected, located
and installed. Data must be conscientiously
The purpose of instrumentation and monitoring collected, meticulously reduced, tabulated, plotted,
is to maintain and improve the safety of analysed and must be judiciously evaluated with
structures by information to : respect to the safety of the dam in a timely
manner. A poorly planned programme will
1 evaluate whether the structure is performing
produce unnecessary data that the structure owner
as expected and
will waste time and money collecting and
2 warn of changes that could endanger the
interpreting, often resulting in disillusionment and
safety of the structure.
abandonment of the programme.
Philosophy of Instrumentation and
Complimentary visual observations
Monitoring
Visual observations of all structures should be
Instrumentation and monitoring must be
made in conjunction with instrumentation
carefully planned and executed to meet defined
monitoring to adequately assess the safety of a
objectives. Every instrument in a structure should
structure. Visual observations can readily detect
have a specific purpose. If it does not have a
indications of poor performance such as offsets,
specific purpose, it should not be installed, or it
misalignment, bugler depressions, seepage,
should be abandoned. Instrumentation for
leakage and making more importantly, visual
long-term monitoring should be rugged and easy
observations can detect variations of spatial
to maintain and should be capable of being
patters of these features. Most visual observations
verified or calibrated. Instrumentation typically
provide qualitative rather than quantitive
provides data to :
information while instruments provide detailed

characterise site conditions before construction,
quantification information. Visual observation and

verify design and analysis assumption, instrumentation data are natural complements and

evaluate behaviour during construction; first when used together they provide the primary
loading and during further operation of the means for engineers to evaluate the safety of the
structure structure.

evaluate performance of specific design This Catalogue

features; Common type of instruments used for monitoring

observe performance of known geological the performance of structures are provided in this
and structural anomaly; catalogue. For each type of instrument, basic
engineering concept and typical applications are

evaluate performance with respect to
discussed. However, for each structure, the specific
potential site-specific failure modes;
instrumentation plan needs to be evolved
Installation of instruments or accumulation of depending on its particular requirements. AIMIL has
instrument data by itself does not improve the a consulting division which provides these services.

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 STRUCTURAL MONITORING

ATES the consultancy division of AIMIL
Structural Instrumentation

Geotechnical Investigation, Slope
AIMIL offers consultancy services in Geo technical
Stabilization & Ground Improvement.
field through our in-house consultancy wing called
Advanced Technology & Engineering Services
Non-Destructive Testing of Structures &
(ATES). Rehabilitation.

ATES comprises of a team of highly skilled
Numerical Modelling.

qualified professionals practicing in the following
Structural Designs.
areas:

In-Situ Rock Testing for obtaining design
parameters

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 STRUCTURAL MONITORING

Applications :
CASAGRANDE POROUS The measurement and control of water pressure
TUBE PIEZOMETER in soil and rock, including :

Construction control and stability monitoring
Purpose of embankments, dams and reservoirs.
Casagrande Porous Tube Piezometers are used for
Stability investigations of natural and cut slopes.
measuring and controlling pore water pressure in

Control of dewatering and drainage operations.
soil, rock and to monitor the construction control

Hydrological investigations.
and stability in embankments, dams, and reservoirs.

Pollution and environmental studies.
Operating Principle :

Construction control of shallow underground
A standpipe, with a porous piezometer tip works.
connected at its lower end, is installed in a borehole.

Permeability measurement.
Bentonite and/or grout are used to seal the borehole
above the tip. Water level inside the standpipe is Installation :
measured with a Water Level Indicator, and The Porous tube Piezometers are generally installed
corresponds to the water pressure at the piezometer in boreholes. Coarse sand filter material is placed
elevation. Permeability of soil in the vicinity of the at the base of the piezometer tip. The piezometer
tip can be determined, when required, by tip coupled to the standpipe, is lowered to rest on
increasing the water head in the standpipe and the sand. Additional sand is poured until the tip is
observing its rate of dissipation. covered by at least 150 mm sand above the tip.
Advantages : Bentonite plug is placed over the sand filter and

Ideal piezometer to ascertain the piezometric back filling is completed with bentonite, cement
level during routine site investigation. or any other type of grout. Water level readings
are taken using electronic water level indicator. A

Can be installed after completion of Bourdon Tube pressure gauge may be used for
construction and therefore suitable for use in reading water pressure in artesian conditions.
existing dams / embankments.

Simple and reliable for long term observations AIM 701 Casagrande Porous
or for short term readings in highly permeable Tube Piezometer
ground. Ref. Standard IS : 7356 (Part 1)
Casagrande Porous Tube Piezometer is made up
of porous carborundum and alundum tube of a

AIM 701 POROUS TUBE PIEZOMETER

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 STRUCTURAL MONITORING

similar cross section, 38 mm OD, 6 mm wall AIM 70102 Semi-Rigid Plastic Stand Pipe
thickness and 600 mm length, by joining 200 mm 27 mm OD, 17/18 mm ID,
Porus Tubes. length 3 m.
Installation Accessories : AIM 70104 Protective Pipe
100 mm dia x 1 m long with
AIM 70103 Top Plug with Nipple.
lockable cap.
AIM 70101 Semi-Rigid Plastic Stand Pipe
AIM 70105 Protective Pipe
27 mm OD, 17 mm ID, length 1 m.
150 mm dia x 1 m long with
lockable cap.
AIM 705 Electronic Water Level Indicator
with marked flexible cable for
depth upto 30 m.
AIM 706 Electronic Water Level Indicator
with marked flexible cable for
depth upto 50 m.
AIM 707 Electronic Water Indicator
with marked flexible cable for
depth upto 100m.
AIM 708 Electronic Water Level Indicator
with marked flexible cable for
AIM 705 ELECTRONIC WATER LEVEL INDICATOR depth upto 150m.

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Thermister : In built YSI-44005 or equivalent,

UPLIFT PRESSURE (3k Ω @ 25°C).
MEASURING SYSTEM Cable : 4 core shielded, 1 m
Installation Accessories :
Purpose
Cables and Splicing Kits :
Uplift Pressure meters are used for measuring and
recording of uplift pressures acting in foundations AIM 89011 Shield Cable, PVC, multi strand
of concrete/masonry dams. shielded, 2 pair (4 core)
AIM 89101 PVC Splicing Kit
AIM 711 Uplift Pressure Pipe & AIM 89012 Armoured Cable:
Head Assembly Unit Armoured cable (Heavy Duty)
single pair (2-core) 12mm dia.
AIM 71101 GI Pipe 50 mm nominal bore,
1 m long AIM 89102-2 Splicing Kit
Splicing Kit stainless steel
AIM 71102 GI Pipe 50 mm nominal bore,
3 m long AIM 89013 Armoured jelly filled cable, 2 pair
(4-core) 16 mm dia.
AIM 89014 Armoured Cable
Armoured jelly filled cable, 3 pair
(6-core) 16mm dia.
AIM 89015 Armoured Cable
Armoured jelly filled cable,
10 pair (20 core)
AIM 89016 Armoured Cable:
Armoured jelly filled cable, 20 pair
(40-core)18/19mm dia (approx)
AIM 711 UPLIFT PRESSURE PIPE & HEAD ASSEMBLY

AIM 71103 Metallic filter tip AIM 892 Watertight Junction Box
50 mm ID, 60 cm long
AIM 89301 Cable termination and switch box
AIM 711-I Vibrating Wire Type Uplift
for connecting 10 individual
Pressuremeter
instruments to Readout Unit
Comprises of Vibrating Wire sensor with through rotary switch.
following specifications : AIM 89301-1 Cable termination and switch box
Range : 3/7/10/20/35/50 bar for connecting 13 individual
Over Range : 150 % of range instruments to Readout Unit
Accuracy : ± 1% FS (0.5% optional) through rotary switch.

Material : Stainless Steel AIM 89302 Cable termination and switch box
Operating : – 10°C to +70°C for connecting 25 individual
temperature instruments to Readout Unit
through rotary switches.
Coil : 140 - 160 ohm
Resistance

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Hydrological investigations and for water

TWIN TUBE HYDRAULIC supply projects.
PIEZOMETER
Pollution and environmental studies

Permeability measurements.
Purpose
Twin Tube Hydraulic Piezometes are used for Installation
measuring and controlling Pore Water Pressure in Foundation or Bishop type tips are installed in
earthen dam. boreholes at predetermined levels in the foundation
of any structure. The embankment type
Operating Principle piezometers are installed in the body of earth dams
The System comprises of porous element connected and at concrete-soil interface. The twin tubes are
to a readout unit by a flexible twin tubing filled protected against any possible damage during
with de-aired water. The pore water pressure can construction. Pore water pressure is measured using
be determined at the readout location by means of bourdon gauge unit or transducer readout unit.
a Bourdon gauge unit or transducer readout unit
It is essential that neither the readout gauge nor
incorporating digital display. The inaccuracies due
the highest level of tubing should be located at
to air entrapment and gas accumulation in the
height more than 5 m above the piezometric level.
piezometer tip can be avoided by using de-aired
water and by flushing this with water, prior to AIM 713 USBR Embankment
taking readings. Type Piezometer
Ref. Standard IS:7356 (Part 2)
Advantages
This Piezometer comprises of two Ceramic Filter

Suitable for remote readings.
discs with following specifications :

Reliable and accurate for long term use. Diameter : 25 mm.

Avoids inaccuracies due to air entrapment and Thickness : 6 mm.
gas accumulation at the Piezometer tips. Air Entry Value : 147kN/m 2approx.

Accurate and simple permeability Permeability : 2x10-7 cm/sec approx.
measurements.
AIM 714 USBR Foundation Type

The high air entry tip permits measurement of
Piezometer
negative pore water pressures for use in partially
Ref. Standard IS:7356 (Part 2)
saturated soils.
The Piezometer comprises of two Ceramic Filter
Applications discs with the following Specifications:
The measurement and control of water pressure Diameter : 25 mm.
in soil and rock including:
Thickness : 6 mm.

Construction control and stability monitoring Air Entry Value : 147 kN/m2 approx.
of the foundations, embankments of earth
Permeability : 2x10-7 cm/sec approx.
dams, surface excavations and shallow
underground works. AIM 715 Bishop Type Foundation

Stability investigations of natural and cut slopes. Piezometer

Uplift Pressure and hydraulic gradients in dam Bishop type Foundation Piezometer comprises of
foundations and abutments. tapered Ceramic Filter Cone with following
specifications :

Control of de-watering and drainage operations.

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AIM 722 Digital Pore Water

Pressure Reading Apparatus
For upto 6 Piezometer Tips, consists of a readout
panel with valves, pressure gauge, electrical
transducer, cable, connectors and 3½ digit Digital
Indicator suitable for use with 220 V, Single Phase,
50 Hz, A.C supply.

AIM 713, 714, 715 PIEZOMETERS

Diameter : 50 mm to 38 mm.
Filter length : 100 mm.
Total length : 155 mm.
Air entry value : 147 kN/m2 approx.
Permeability : 2x10-7 cm/sec approx.
Readout Units
AIM 716 Ready to Install Terminal
Well Equipment.
It consists of an Operating Panel assembled on fibre
glass coated wooden panels as per BIS
specifications, comprising of hand operated pump,
Acrylic plastic air trap, Master Gauge, Cartridge
type water filter, water reservoir, manifold, shut-
off cock etc.

AIM 717 Ready to install Terminal

Well Equipment
Same as AIM 716, but with an additional Electric
Water Pump. AIM 716, 722 DIGITAL PORE WATER
PRESSURE READING APPARATUS

AIM 719 Readout Assembly

AIM 723 Digital Pore Water Pressure
Consisting of valves and gauges to read upto 6
Reading Apparatus
Piezometers at a time, complete with brass
shut-off cocks etc. These are assembled on fibre For upto 20 Piezometer Tips, consisting of terminal
glass coated wooden panel with an additional panel panel with valves, pressure gauge, electrical
for clamping twin tubes. transducer, cable, connectors and 3 ½ digit Digital
Indicator suitable for use with 220 V, Single Phase,
AIM 720 Portable Pore Water Pressure 50 Hz, AC supply.
Readout Panel Installation Accessories for
Consists of complete set of equipment for reading
AIM 713, AIM 714 & AIM 715
upto 5 Piezometer tips for use during construction.
AIM 71301 Plastic Tubing
8 mm OD.

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AIM 71304 Brass Compression Double AIM 71311 Aerol OT

Union 10% solution.
with nut, ferrule and insert.
AIM 71312 Copper Sulphate Crystals
AIM 71303 Plastic cap in 10 g packet.
for 8 mm OD plastic tube.
AIM 71313 Bentonite Clay
AIM 71305 Identification Tags Pack of 10 kg.
set of 6 inlet and 6 outlet tags.
AIM 71306 Brass Plug
with nut, ferrule and insert.
AIM 71311 Test Pump
for field use during installation.
AIM 71307 Reel Rack.
AIM 71308 Tube Spacing Rack.
AIM 71309 Plastic Spacer.
AIM 71310 Wooden Separator
for use in trenches. AIM 723 TERMINAL PANEL WITH ACCESSORIES

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for actual measurement from embedded

SIMULATOR FOR TWIN piezometers.
TUBE PIEZOMETER SYSTEM
AIM 725 Simulator for Twin Tube
Piezometer System
Applications
Simulator comprises of Operation & Readout

For demonstration to students. Panel and Piezometer module

For operator training. Operating and Readout Panel consists of :

For use as a portable field unit.
A) AIM 72501
Introduction
Hand pump.
Air trap.
The Twin-tube Piezometer System has been in use
Filter.
Master gauge.
for many years for field measurement of pore water

Operating panel gauge.
pressures in soil and rocks. Although this system

One pair of inlet and outlet gauges for
has been described in detail in the Earth Manual
piezometers.
and other publications, no apparatus has existed so
far, which can demonstrate the principle of operation
Gauge for piezometer module.
of twin-tube piezometer in the laboratory.
Needle valve.
Water reservoir.
It comprises of operating and readout panel
Screw pump.
Open-shut valves.
connected to a piezometer module. The panel is
identical to the panel specified in IS Code for use in B) AIM 72502 Piezometer Module, consists of:
the field. The module comprises of a chamber under
Acrylic chamber.
which a piezometer is buried in soil under simulated
USBR Embankment type Piezometer.
field conditions. Also, this system has two extra pairs
Quick release connectors for tubing from
of inlet and outlet valves which can be connected to piezometer tips and from panel.
additional piezometer tips in separate modules.
Water inlet connector.
The system can be used for demonstrating de-airing

Pair of rubber sealing rings.
and pore water pressure measurement operations,
as done in the field. This system is therefore, useful Optional Extras
for students and operator training. The system is AIM 72503 Piezometer Module
portable and can be taken to the field, if required, (same as item ‘B’ above, except that
the piezometer is USBR Foundation type)

AIM 72504 Piezometer Module

(same as item ‘B’ above, except that the piezometer
is Bishop type)
We can test and
simulate the
parameters of
embankment as well
as foundation type
h y d r a u l i c
piezometers in the
above simulator
module.

AIM 72501 PIEZOMETER MODULE

AIM 725 SIMULATOR FOR TWIN TUBE PIEZOMETER SYSTEM

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Installation :
PNEUMATIC PIEZOMETER
The transducer can operate in any position. It can
Purpose : be installed in borehole or pressed into soil by
Pneumatic piezometers are used for measurement points attached to steel pipes; can be pushed into
the soil and does not require drilled holes.
and control of pore water pressure in fills.
In most applications, the 27 mm OD transducer is
Operating Principle : embedded in an open borehole and is sealed-off
The Piezometers are sealed in boreholes from other water bearing areas with bentonite or
embedded in fills or fixed in standpipes. Twin cement grout. The tubing may be embedded
tubes run from piezometer to a terminal on the directly in trenches, using sand backfill to prevent
surface. The piezometer contains a flexible rocks or other sharp objects from damaging the
diaphragm. Water pressure acts on one side of the tubing. In cases where large lateral or vertical
piezometer diaphragm and gas pressure acts on deformations are expected, the tubing can be
the other. When piezometer is not active, the water protected by an armoured conduit.
pressure on piezometer seals off the vent tube.
When a reading is required, gas is supplied from
the pneumatic indicator to one side of the flexible
unit. The reading is obtained when gas pressure
balances the ground water pressure on the other
side of the diaphragm.

Advantages :

Simple, accurate, reliable and robust, avoiding
many of the problems associated with electrical AIM 727 PNEUMATIC PIEZOMETER
instruments.

Volume change is less, therefore fast response.
AIM 726 Pneumatic Piezometer

No corrections need to be made for differences Pressure : Upto 400 kPa
in elevation between piezometer and readout. Accuracy zero : 2 ± 0.35 kPa

Corrosion resistant plastic construction and offset
direct burial polyethylene tubing is used. Sensitivity : 1.000 ± 0.0005 kPa

Can be installed in horizontal and up-holes outpur / input
which is ideal for underground works. Outer dia : 27mm
Length : 75mm
Applications :
Pneumatic Piezometers are placed in boreholes, Material
suspended in standpipes or embedded in fill
Body : PVC or ABS plastic
material. Typical applications include:
Filter : Sintered bronze or Stainlessteel,

Monitoring the effectiveness of dewatering and pore size 50 Micron, low air entry type.
drainage scheme.
AIM 727 Pneumatic Piezometer

Evaluating ground stability.
Pressure : Upto 2600 kPa

Determining safe rates of fill or excavation.
Accuracy

Monitoring water table elevation. Zero offset : 2 ± 0.35 kPa
Sensitivity

Monitoring the contaminants of tailings or
Output/input : 1.000 ± 0.0005 kPa
hazardous waste materials.
Outer Dia : 27 mm

Monitoring earth structure performance. Length : 75 mm

10

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Material Accuracy : ± 0.5% FS

Body : PVC or ABS Plastic Display : 3 ½ digits operates on rechargable
Filter : Sintered bronze or Stainless steel, battery
pore size 50 micron, low air entry Gas source : Portable gas cylinder
type housed in the Indicator
AIM 72601 Pneumatic Indicator AIM 72702 Twin tubes, 1.5 mm
with Pressure Gauge, 150 mm dia Nylon with Polyethylene Jacket, for
Operating use upto 2600 kPa capacity
Pressure : 0 - 200 or 0 - 400 kPa Outer Dimension : 12 mm x 7 mm
Accuracy : ± 0. 5% FS Installation Accessories
Gas Source : Foot Pump AIM 72603 Splicing Kit, for twin tube.

lndicators upto 2600 kPa capacity can AIM 72604 Foot Pump
be supplied on request. The above foot pump is used as an installation
AIM 72602 Twin tubes accessory the above Pneumatic Piezometer set up.
low density polyethylene with
polyethelene jacket, for use
upto 400 kPa capacity.
Outer Dimension : 12 mm x 7 mm
Tube material : Polyethelene, 4.5 mm
OD x 1 mm thick
Jacket material : Polyethylene
AIM 72701 Pneumatic Digital Indicator
Operating
pressure : Upto 2600 kPa

AIM 72601 PNEUMATIC INDICATOR

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Construction control and stability monitoring

VIBRATING WIRE of foundations, embankment, retaining walls
PIEZOMETER anddams.

Stability investigations of natural and cut slopes.
Purpose
Monitoring pore water pressure during
Vibrating wire piezometers are used for permeability testing, dewatering and drainage
measurement and control of pore water pressure in work.
all structures and in ground to monitor water table.
Geohydrological investigations including
ground water elevation, wells, irrigation and
Operating Principle :
water supply.
The basic principle of the vibrating wire

Measurement of pore water pressure related to
transducer is that the change in natural frequency
pollution and environmental studies, pipe line
of stretched wire depends on the change in the
leakages.
tension of the wire. In this instrument, one end
of the gauge wire is attached to the center of a
Construction control and stability monitoring
circular membrane and the other end is screwed of tunnels and other underground works.
to the top of the transducer housing.
Fluid pressure applied to the membrane causes
deflection of the membrane, with consequent Borehole Installation
change in the tension of the wire and its resonant The Vibrating Wire Piezometers are easy to install.
frequency. Thus, the frequency of the gauge wire A borehole of diameter 75-200 mm is usually made
is a measure of the deflection of the membrane, in soils using shell and auger techniques and in
which is proportional to the pressure change. rocks with rotary drilling. The sides of the hole in
the vicinity of the piezometer tip should be free
Advantages : from mudcake and debris. If the hole requires

Accurate, robust and with very good long term casing, this is withdrawn to keep pace with the
stability. installation. Coarse,

No signal losses in cables, thus permitting signal clean sand filter material is placed through water
transmission over long distance. in the proposed base of the piezometer tip. The
piezometer tip soaked in water for at least 24 hours

Capable of measuring negative pore pressure
is inserted in the borehole. Further, filter sand is
to –5 meters head of water.
poured until the tip is covered by at least 150mm.

No corrections need to be made for difference
A plug to prevent entry of grout into the sand cell
in elevations between Piezometer tip and
is usually placed in the form of bentonite granules
readout unit.
or balls dropped through water. Backfilling is then

Can be installed in horizontal and upholes: ideal completed to ground surface with impervious
for underground works. grout, generally a bentonite cement mix, placed

Suitable for remote reading, scanning and data through a tremie pipe positioned above the
logging. bentonite plug and withdrawn as grouting

Fast response to pore pressure changes due to proceeds. Alternatively, for shallow holes, backfill
low volume change. may be carried out using bentonite/cement pellets.

Hermetically sealed with inert gas. When placing of sand filter material is difficult or
drilling of large diameter holes uneconomic of the
Applications : piezometer tip may be installed in percussive drilled
The measurement and control of pore water holes greater than 45mm diameter.
pressure in soil and rock include :

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Shallow Soil Foundations : AIM 729 Vibrating Wire Piezometer

A shallow trench is excavated to take the cable and Range : 0-3, 5, 10, 25, 50 and 100 Bar
to remove grass and root material from the vicinity (customer to specify)
of the tip. The piezometer tip can be pushed into Diameter : 20 mm
soft soils, using a placing adaptor and placing
Accuracy : ± 0.5 % FS
tubes. Alternatively short holes may be drilled with
Coil Resistance : 140 - 160 Ohm
a hand or powered auger and the tip pushed a
Operating : – 10 to + 70° C
further 300 mm into soil at the base of the hole.
Temperature
Installation of Cables and Terminal
Equipment : Thermistor : Inbuilt YSI – 44005 or
equivalent, (3k Ω @ 25°C).
Piezometer cables must be protected from
Material : Stainless Steel
mechanical damage. In earthworks these are
Maximum : 150% of range
grouped loosely at the base of a trench
Overpressure
approximately 600 mm deep, protected above and
Filter type
below with 150 mm of stone-free sand or clay. In
Standard : High Air Entry Ceramic
other situations, the cables may be run in protective
Coating : Polyster Coating for sea/saline
conduit or cast into concrete. The tubes should be
water applications
looped where they cross an interface and at joints.
Sealing : Hermetically sealed with inert
This reduces strain in the cables and joints due to
gas, meets IP - 68, weather
differential movement.
protection clause
When there are sufficient piezometer installations Optional : a) Low Air entry Ceramic
to justify use of an instrument house, the cables b) Low Air entry Sintered
are led through an entry duct which may be cast Stainless Steel.
into the concrete floor and connected to a switch Cable : 4 - Core shielded , 1 m
box or terminal panel attached to the wall. Readings
are taken by connecting twin flyleads from the
portable readout unit to a common plug-in
connection and by switching to respective
channels.

AIM 729 VIBRATING WIRE PIEZOMETER

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Applications :
CROSS ARM

Monitoring of earth and rockfill dams.
SETTLEMENT SYSTEM

Construction control of road embankments.
Purpose :
Monitoring of foundation settlements.
Cross Arm Settlement Systems are used for
Monitoring of bridge abutments and
measuring settlement in earth fill dam, rock fill dam retaining walls.
and high embankment.

Monitoring of vertical movements.
Operating Principle :
Installation :
Telescopic steel tubes are embedded in fill, with
Prior to installation of the test equipment,
each of the smaller diameter tubes anchored to the
permanent instrument benchmarks and targets are
fill by a steel cross arm. To take the readings, a
established on the abutments of the embankment.
portable measuring head is fixed to the upper tube.
The installation comprises of a series of alternate
A torpedo suspended from a steel measuring tape
telescopic 40 mm dia and 50 mm dia pipe sections,
is lowered through the head and down the tubing.
anchored to the embankment by horizontal cross
Each time the torpedo passes the base of one of arms. To prevent the ingress of soil, all telescopic
the smaller diameter tubes, the tape is pulled taut. joints are protected with oakum or hemp packing,
Spring-loaded prawls in the torpedo press held in place by hessian wires on to the pipes. The
outwards and engage the base of the smaller tube. cross arms are installed progressively as the
Depths are measured from the measuring head to
the base of each small tube. On completing its
measuring traverse, the torpedo contacts a latching
plate fixed in base tube of anchor cross arm. The
weight of the torpedo activates a mechanism to
retract the prawls allowing the probe to be
withdrawn.
All movements can be referred to the lower end of
the access tube, set in a borehole below the level at
which movement occurs. Alternatively,
conventional surveying methods are used to
establish the elevation of the measuring head
reference mark. Depth readings are thus converted
to elevations and amounts of settlement or heave
are deducted from the initial values. Settlement at
the base of one of the smaller tubes is taken as equal
to settlement at the cross arm anchor, to which it
is fixed.
Advantages :

Reliable and robust.

Simple to install and read.

One torpedo can be used at many locations.

Settlement readings are obtained at frequent AIM 73108 TORPEDO
intervals down the tubing.

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 STRUCTURAL MONITORING

embankment is placed. Settlement readings are

obtained after adding each length of the tubing
by means of specially designed measuring torpedo.
The torpedo is lowered into the pipe barrel by
means of a steel tape, so attached that the upper
edge of the torpedo corresponds to zero point of
graduation of the tape. While making a
measurement, the torpedo is lowered to a point a
few centimeters below the elevation of the upper
most measuring point and then lifted until the
extended prawls engage the lower end of the inside
40 mm dia pipe.

AIM 731 Cross Arm Settlement System

Cross Arm Unit , steel channel,
75 mm ISMC, 600 m long
Spacer Section :
Diameter : 50 mm
Length : 1500 mm
Spacing between : 2000 mm (rock free soils)
Cross Arms
Top Extension : 50 mm
Diameter
Installation Accessories :

AIM 73101 Anchor Cross Arm

AIM 73102 Base Section with latching plate
AIM 73103 Cross Arm
AIM 73104 Spacer Section 1.5 m spacing
AIM 73105 Spacer Section 2.5 m spacing
AIM 73106 Top Extension
AIM 73107 Top Cap and Plug
AIM 73108 Brass Measuring Torpedo
without Steel Cable
AIM 73109 Steel Measuring Cable, 50 rm
AIM 73110 Reading Scale with Adapter
AIM 73111 Tool Set
AIM 73112 Oakum
AIM 731 CROSS ARM INSTALLATION IN EMBANKMENT
AIM 73113 Cloth Bag

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AIM 73203 PVC Protection pipe

BASE PLATE semi rigid, 60mm ID x 2 mm
SETTLEMENT SYSTEMS thick, with Coupling, 0.5 m long.
AIM 73204 PVC protection pipe
Purpose : semi rigid, 60mm ID x 2 mm
Base Plate Settlement Systems are used for thick, with Coupling, 1.5 m long.
measuring and monitoring of settlement below the
embankment on soft ground.

Operating Principle :
A settlement platform consists of a square plate of
steel (normally 0.5, 1 or 1.2 m square) placed on
original ground surface to which a riser pipe of 50
mm dia is welded.
Optical level measurements to the top of riser pipe
provides a record of the plate elevation position
which may change with the passage of time. Pipe
should be maintained vertically and additional pipe
lengths used for recording as the fill placement
progresses.
An initial reference mark should be scribed on the
riser pipe and its elevation observed and recorded.
The pipe should be scribed at intervals of 1.5 m to
an accuracy of 3 mm and the graduations be
numbered to reflect the distance from the initial
scribe.
Applications :
These are typically used for monitoring settlement AIM 732 BASE PLATE SETTLEMENT SYSTEM

below embankments on soft ground

Installation :
SETTLEMENT POINTS
Successive lengths of tubes are installed till the AIM 733 Surface Settlement Point
general level reaches the top of the tube. When Made of 250 mm long, 25 mm dia,
final level is reached, a cover may be set in concrete steel rod having cross mark on the top.
over the tube collar to provide added protection. Surface Settlement Point are used for monitoring
AIM 732 Base Plate settlement system the settlement of the top surface. The steel rod has
got a cross mark engraved at the top and the
Made of Steel, 0.6 m x 0.6 m x 5 mm thick, with
settlement is monitored using a theodlite at regular
male threaded coupling welded at centre.
intervals. The first reading acts as a reference and
Installation Accessories : the subsequent readings gives the settlement of the
AIM 73201 Extension Pipe surface with respect to time.
Class A, 40 mm nominal bore, AIM 734 Parapet Settlement Point
with Coupling, 0.5 m long Consisting of a 25 mm dia, 150 mm
AIM 73202 Extension Pipe long Steel rod welded to the 225
Class A, 40 mm nominal bore, mm x 75 mm x 6 mm Steel Plate.
with Coupling, 1.5 m long.
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MAGNETIC SETTLEMENT
SYSTEM

Purpose :
Magnetic Settlement System is used for measuring
and recording of settlement in the earthen dam,
embankment, ground etc.

Operating Principle :
Ring magnets, sliding on a central access tube are
fixed in the ground at the locations, where the AIM 735 MAGNETIC SETTLEMENT SYSTEM
movement is to be monitored. Various types of
magnet targets are available; they can be grouted After adding each length of tube, an end cap is
in rock or retained by leaf spring arrow head or fitted to prevent the entry of dirt while the next
plate fixtures in soil or fill. A probe incorporating layer of fill is being placed.
one or more reed switches travels within the tube.
Horizontal Installation :
The reed switch closes on entering the magnetic
field and activates a buzzer and indicator light on The telescopic access tubes are laid at the base of
the readout instrument or cable drum. the trench, with magnet plates embedded in the
trench floor. Care should
Applications : be taken during back filling to prevent the damage
The measurement of soil and rock movements or disturbance to the equipment.
include:
Installation in Downward Boreholes :

Settlement, heave and lateral movement, in the
A borehole of 100 mm to 225 mm is usually drilled in
foundations and embankments.
the soils by using shell and auger, and in the rocks by

Displacement of retaining walls, bridge piers
using rotary water flush drilling.
and abutments.
The borehole is to be backfilled with fill materials

Movement of natural and cut slopes, quarry
grout, which should be at least as deformable as
and mining excavations.
the ground in which the instrument is to be

Subsidence. installed.

Relaxation of rock around tunnels and other End cap is cemented to the bottom of first length
undergound openings. of access tube which is then inserted into a hole.
Further sections of tubing are coupled with an
Installation guidelines :
adhesive until the end cap reaches the base of the
Installation in Fill hole.
Magnetic Settlement System in the fill, generally Spider magnet targets are placed one by one over
employ access tubes and rectangular plates, which the access tube and pushed through the grout to
are usually installed in a trench. the required location by using the placing head and
placing tubes.
Vertical Installation :
The magnet is secured to the ground both by the
Three metre lengths of tubing are added one by springs and the fill material.
one to keep pace with the fill operation.

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AIM 735 Magnetic Settlement System AIM 73507 Protective Pipe with Lockable Cap
Installation Accessories : 150 mm dia x 1000 mm long
Select from following accessories
AIM 73508 Tool Kit.
AIM 73501 Extensometer magnet, with Prongs Spare :
(spider magnet) for bore holes.
AIM 73509 Sensing Probe.
AIM 73502 Extensometer magnet
Fixed in PVC plate size 300 x 300 x
25 mm for embankments.

AIM 73503 Readout Reel

Battery Operated, portable, with
Electric Cable 50 m long, and
sensing probe.

AIM 73504 Rigid Plastic Pipe

33mm OD x 24mm ID, in length
approx. 1.5 m with male/female
threaded ends

AIM 73505 Rigid Plastic Pipe

33mm OD x 24mm ID, in length
approx. 3 m with male/female
threaded ends

AIM 73506 Top Cap and Bottom Plug

AIM 73501, 2, 3 SENSING PROBE WITH PLATE AND
SPIDER MAGNETS & READING SCALE

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Applications :
LIQUID SETTLEMENT CELLS
The measurement and control of vertical
VIBRATING WIRE TYPE movements include:

Construction / control of road embankment and
Purpose : earth dams.
Liquid Settlement Cells are meant for the
Settlement and heave of oil tanks and building
foundations.
measurement and control of vertical movement in

Monitoring of bridge piers, abutments and
earth/rock fill dams, using vibrating wire sensor, and
retaining walls.
a water chamber connected to the terminal panel
Control of subsidence.
through pair of nylon tubes filled with water.
Construction control of marine fills.
Operating Principle :
Installation :
The cell consists of a vibrating wire transducer with
Cells should be installed at a level lower than the
an integral water chamber. A pair of nylon tubes
liquid datum pot at the terminal location. The
and an armoured cable extended from the cell to
difference in the elevation between the cell and
the readout terminal located on a stable ground.
datum pot must be within the cell range, making
The nylon tubes are filled with water and connected
allowance for anticipated settlement or heave.
at one end, to a perspex datum sight pot and at the
The vibrating wire transducer monitoring location
other end to the transducer liquid chamber.
can be positioned away from the liquid datum
The cable connects the transducer to the terminal
pots, as required.
panel. Vertical movement of the cell in relation to
the readout location results in a change in liquid AIM 736 Vibrating Wire Settlement
pressure within the chamber. To measure the
Cell, Borehole Type
change in pressure and hence the amount of
Range : 5m to 30m
settlement or heave at a particular point, a vibrating
wire readout is connected to the transducer cable Coil Resistance : 140 - 160 Ω
to provide a direct reading of fluid pressure acting Operating : – 10 to +70° C
on the cell. The pressure is displayed on the readout temperature
is converted in meters of water and can then be Accuracy : ± 0.5% of FS
recorded for comparison with previously recorded Cable : 4 - Core shielded , 1m
data.
The water level in the datum sight pot may require
AIM 737 Vibrating Wire Settlement
small adjustments from time to time to Cell, Trench Type
compensate for volume changes that occur due to Same as AIM 736, but for installation in trenches.
stretching of the liquid tubing.
Installation Accessories :
Advantages :
AIM 73601 Pair of Nylon Tubes

Reliable, simple to install and read. 2 x 4 mm dia

Measurement can be made beneath concrete
and earth structures at the locations which are AIM 73602 Acrylic datum sight pots
inaccessible to other types of instruments
AIM 73603 Terminal Panel

No vertical rods or tubes to interface with
construction.

Unaffected by lateral movements.

Twin liquid lines allow for re - circulation of
water through the system after installation.
In-situ calibration tests, if required, can be done.

Large operating range.

Portable readout unit can be used in conjunction
with other Vibrating Wire instruments. AIM 737, 875, 73603 LIQUID SETTLEMENT CELLS

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identical depths.
DIGITAL INCLINOMETER Comparison of successive casing profiles indicates
Purpose : the location, direction, magnitude and the rate of
change of movement. The clearest indication of
Digital Inclinometer System measures and movement is given by plotting the change in
monitors the lateral deflection in X-Y Plane of soil/ deviation of the casing against depth. Settlement
rock. It can be used in monitoring lateral movement, or heave occurring in the ground surrounding a
horizontal movement and inclined movement. borehole installation will cause compression or
Operating Principle : extension of the inclinometer casing.
The Soil Instruments’ biaxial inclinometer system Advantages and Limitations :
comprises a probe, fitted with guide wheels and

The inclinometer system is simple to install,
containing accelerometers, connected by a
reliable and provides accurate measurements.
graduated cable to the cable reel, a “key fob’’
activates the reading being taken and this is
The system provides readings of lateral deviation
transmitted to a PDA via Bluetooth cable free in two orthogonal planes over the complete
transmission. length of the access tubing.
The inclinometer probe is inserted into the keyways
The probe, cable drum and PDA are light and
of specially installed inclinometer casing such as easily portable.
Soil Instruments’ EC casing. The accelerometere
Cable is moulded to the probe for long-term
enables lateral deviation between the probe axis reliability and integrity.
and the vertical plane to be recorded. Measurement
No connectors throughout the system.
of deviation and depth are used to compute the

PDA allows readings to be emailed to office or
lateral position of the installed casing from true
client from site.
vertical. The casing can be grouted into a borehole,
embedded in fill or concrete, or secured to the
If PDA fails readings can be stored in the cable
surface of a structure to be monitored. reel.
Two sets of spring guided wheels on the probe, in
Software available for providing a range of data
conjunction with four keyways set at 90° intervals presentation options.
in the casing, ensure constant alignment of the Applications :
probe relative to the required orientation of the
The measurement of lateral displacement of soil,
installed casing.
rock and manmade structures, including:
The design of both the probe and the casing

Shear-plane determination and direction of
therefore enables lateral movements to be
movement in natural and cut slopes.
monitored with high degree of sensitivity and
accuracy.
Monitoring lateral displacement of
embankments and dams.
For borehole or embedded installations the base
of the casing should be firmly placed in stable strata
Deflections of concrete or asphaltic upstream
beyond the anticipated zone of movement so that membranes on dams.
any lateral movement is related to a fixed datum
Deflection of bridge piers, piled foundations,
port. abutments. retaining and diaphragm walls.
Telescopic couplings are used in situations where
Stability of shafts, tunnels and underground
compression or extension of the casing is expected. works.
Displacement readings are taken at 0.5m intervals
within the casing, measured by graduation AIM 741 Digital Biaxial Probe with
markers on the cable. PDA Logger
An initial set of inclinometer readings (base The biaxial inclinometer system comprises a probe,
readings) are obtained at specific depths within the fitted with guide wheels and containing
casing and subsequent readings are taken at

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 STRUCTURAL MONITORING

accelerometers, connected by a graduated cable to AIM 74I-03 Cable

the cable reel, a “key fob’’ activates the reading
Comprising four-core polyurethane sheathed
being taken and this is transmitted to a PDA via
cable, incorporating a central Kevlar straining wire.
Bluetooth cable free transmission.
The cable is graduated in 0.5m intervals with
Spcifications : crimped stainless steel markers, numbered at 1m

Working Range ± 30° of vertical. intervals.

Resolution of system 0.07mm.
AIM 74I-04 Cable Drum

Overall System Accuracy ± 2mm per 25m of
(near vertical) casing. For cable lengths 50m, 100m& 200m. Comprising

Battery life 12 hours. an epoxy painted steel frame with carrying handle

System Operating Temperature – 10°C to + and rigid PVC drum flanges. The reel contains
50°C. dalalogging and Bluetooth as well as system power
supply and diagnostics.

AIM 74I-05 Cable Support Gate

Aluminium alloy insert to locate and support the
graduated inclinometer cable. The cable support
gate also protects the cable from frictional damage
against the top of the access tubing.

AIM 74I-06 PDA

The inclinometer readings are read by means of
In-Port software. This is designed to run on any
PDA or Pocket PC that is running the Microsoft
Pocket PC 2003 operating system or later. This
AIM 741 D DIGITAL INCLINOMETER connects with the inclinometer reel using Bluetooth
wireless technology, to give a truly connectionless
Inclinometer Probes and Accessories :
interface. Readings are taken either by means of a
AIM 741-01 Biaxial Inclinometer Probe button in the software or by using a key fob
The probe is fully water proof, incorporating two activator, which allows the software to operate in
accelerometers, excitation electronics and precision “hands-off mode. Check sums are calculated and
A/D converter housed in a stainless steel body. displayed on reading in the second, A180 orientation.
Readings are stored to a database on the PDA for
Accelerometers aligned at right angles to each other
enabling displacement readings to be taken in two
directions simultaneously. Two pairs of centre
pivoting spring loaded wheels with stainless steel
sealed ball race bearings align the probe centrally
within the casing. The probe is moulded to the
control cable with polyurethane resin compound
providing high pressure waterproofing and long
term reliability. The gauge length between the
wheels is 500mm.
AIM 74I-02 Test/Dummy Probe
Comprising a stainless steel dummy inclinometer
probe supplied with 50m of cord and winding
reel-Used to check integrity of installed
inclinometer casings
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subsequent extraction and transfer to PC using AIM 73510 Magnetic Settlement Probe, with
Microsoft’s standard synchronisation software, 50 m marked cable and drum
ActiveSync.
AIM 73511 Same as AIM 74165, but with 100
The system comes complete with a cradle/charger m marked cable.
and PC connector lead for the PDA and a spare AIM 73512 Same as AIM 74165, but 150 m
battery to provide continued operation in the event long marked cable.
of heavy, protracted use.
AIM 74108 Access Tube, plastic, self aligning,
70 mm OD, 60 mm ID, self
aligning PVC tubing with four
internal keyways at 90° to
eachother and four 3.15 mm dia
rivet holes at one end, length 3 m
long.
AIM 74109 Access Tube, Plastic Self aligning,
70 mm OD, 60 mm ID, Self
aligning PVC tubing with four
internal keyways at 90° to each other
and four 3.15 mm dia rivet holes
at one end, 1.5 m long.
AIM 74109 Coupling Plastic, 76mm ID x
300mm long.
AIM 74110 Protective Bottom End Cap, for
AIM 74113 and AIM 74114.
AIM 74111 Locking Top Cap with Padlock for
AIM 741413 and AIM 74114.
AIM 74112 Assembly Tools, complete Set.
AIM 74113 Pop Rivet, aluminium, for standard
coupling (pack of 100).
Easy to Connect Inclinometer Casing
AIM 74114 Pop Rivet Gun.
AIM 74115 Hand Drill, with two No.30 Drill Bits.
AIM 74116 Mastic Sealing Tape, 3mm x
20mm x 10m (for approx. 7 joints).
AIM 74117 Electric PVC Tape,
25 mm (for approx. 5 joints).
AIM 74118 Dummy Probe, for checking
alignment of casing grooves.
AIM 74119 Portable Reel, with 100 m of nylon
line used for lowering Dummy
Probe in Casing
AIM 74120 Plate Mounted Magnet, 300 mm
OD and 76 mm ID for measuring
settlement in earth or rockfill using AIM 741D DIGITAL INCLINOMETER SYSTEM
magnetic settlement probe.
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Applications :
TIL TMETER - LIQUID BASED
The measurement of change of rotation/tilt of
Purpose : structures include :
Tilt meters are meant for measuring tilt/rotation
Buildings and structures adjacent to deep
of structures/monuments affected to deep excavations and diaphragm wall construction.
excavations, underground tunneling and due to

Buildings and structures affected by tunneling
slope movement.
and mining.
Operating Principle :
Buildings and structures undergoing foundation
treatment, compensation grouting and
The Tilmeter is portable and comprises of a high
underpinning.
accuracy capacitive liquid based tilt sensor with
integrated electronics, mounted on a precision-
Rotation of survey monuments embedded in
machined frame. The measuring principle enables landslide areas.
a linear angle output equal to the measuring range
of the sensor.
AIM 749 Tiltmeter
Indexing bars on the sides and base of the frame Measuring Range: ± 10°
ensure accurate location of the tilmeter on tilt plates Resolution : < 0.003°
rigidly attached to the building or structure under Max. : 0.1 % from measuring value
observation. Non-Linearity
The tilt meter is manufactured in 316 stainless steel Transverse : 1 % at 45° tilt
with 4 orthogonally opposed domed datum pins Sensitivity
to locate the indexing bars of the tiltmeter frame. Response Time : 0.3 seconds
Tilt plates are attached vertically or horizontally to Operating : – 20 to + 55° C
the building or structure with either fixing screws Temperature
or epoxy resin. Storage : – 30 to + 70° C
Temperature
To obtain tilt readings, the tiltmeter is connected
Weight : 3.5 kg (less carrying case)
to the Readout/Logger, positioned on the tilt plate
Size, approx. : 165 x 90 x 150 mm (Lx WxH)
and the reading recorded. The tiltmeter is then
Cable : 4 - Core shielded, 1m
rotated through 180° and a second reading
recorded. The two readings are averaged to cancel Essential Accessories :
any face error.
AIM 74901 Tilt plate

AIM 749, 875 LIQUID BASED TILTMETER

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Over range : ± 0.1% FS upto 150%

TILTMERER, VIBRATING effect
WIRE TYPE Humidity : 0 to 100% RH
Material : Stainless steel
Purpose : Sealing : Hermetically sealed with inert gas,
meets IP - 68, weather protection
Tilt meter is meant for measuring tilt/rotation of
clause
structures/Monuments affected to deep excavation
Cable : 2 - Core shielded, 1 m
underground tunneling and by slope movements.
Available : Thermistor for simultaneous
AIM 750 option temperature measurement

Vibrating Wire Type Tiltmeter gives an electrical The Tiltmeter is shipped with damping oil to
signal proportional to the angle of inclination. It is prevent transit damage to the cantilever assembly.
of rugged construction and permits monitoring of The pendulum and the cantilever are secured by
change in inclination/rotation of concrete structures means of three screws which are placed directly
/ high line buidings and tilt in the foundation. under the top cover. During installation the top
cover of the transducer is opened and the three
The tiltmeter consists of a pendulum supported
supporting screws are removed.
on a precision cantilever. The deflection of the
centilever on both the sides of the normal position, Tiltmeter is installed by inserting the expandable
increases or decreases the tension in the magnetic anchors in the 10 mm dia x 75 mm deep drilled holes.
wire. This change in tension in the magnetic wire
is converted to a frequency variations proportional
to the tilt.
The vibrating wire sensor is extremely accurate
precision tilt measuring device.
Specifications :
Range : ± 1°, 2°, 5° and 10°
Accuracy : ± 1% FS
Coil Resistance : 140 - 160 ohm
Insulation : > 500 ohm at 12V DC
Resistance
Temperature : – 10° to +70° C.
Limit AIM 750 TILTMETER

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HANGING PENDULUM
Purpose :
Normal/Hanging pendulum is used in
monitoring of deflection of dam.

Operating Principle :
The Hanging Pendulum uses a wire and T-square
or vernier Microscope. The upper end of wire is
anchored to the structure under observation. A
weight suspended from the lower end is free to NORMAL PLUMB LINE ASSEMBLY
move in an oil tank, the oil serving to damp the
oscillations of the wire. The wire remains vertical Installation :
but it moves with the structure, from which it is Drill holes and access ducting are prepared.
suspended, therefore, the readings of movement Measuring units, fixed to the appropriate support
relative to the wire must be corrected for frames, are placed in approximate position on their
movements of the anchor. Inverted and Hanging concrete base pads. One end of the pendulum wire
Pendulums are often used together in the same is fixed to the anchor bolt, the anchor pivot pin
structure, in which case all movements may be locates in the SS eyelet on the wire. The other end
related to the inverted pendulum anchored at a of the wire is threaded through the pulley on the
depth in stable ground. T-square or Vernier plumb weight and is secured by two wire clamps.
Microscope is used for taking readings of the
displacement.

Advantages :

Measuring accuracy can be greater than that
obtained by precise geodetic surveying.

Movement can be observed at frequent intervals
without repeated costly surveys.

Instrument errors and ambiguities are avoided.

Pendulum instruments are simple and therefore
reliable in long term use.

Applications :
In general, the Hanging Pendulum monitors the
horizontal movements. Its specific applications are
as follows:

To measure displacements in dams, dam
foundations and abutments

To determine the structural and foundation
movement of tall buildings

AIM 755 HANGING PENDULUM

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The weight, suspended by installing a cord, is Resolution 0.01 mm

lowered down the hole. The anchor unit is Accuracy 0.1 mm
prepared for installation by cutting the rubber Table size 625 mm x 625 mm
grout stop washer to a diameter slightly larger than Stainless steel wire 1 mm x 60 m long
that of the hole. The washer is secured to the anchor (other lengths
bolt by the nuts located above the pivot pin. A cross available)
beam is fixed to the bolt at the upper end. The Wire suspension Collet on
anchor assembly is then pushed into the hole and rectangular bar
adjusted so that the cross beam rests across the grouted at the top
diameter of the hole, with the anchor bolt along Suspension wt./Wire
the hole axis. The space above the grout stop washer tension 10 kgf
is filled with cement mortar or concrete. The oil Tank PVC - 40 litre
tank is placed in position and the weight is adjusted capacity
so that it swings freely in the tank. The wire clamps Damping Oil S.A.E. 40
are tightened and surplus wire is removed. The
tank is filled with oil sufficient to cover the weight. Note :
The measuring units are then centralized with The Stainless Steel wire of 1 mm diameter is
reference to the taut wire. Each support frame suspended from the top of the dam through the
should be securely bolted to its concrete base. collect and it is permanently connected with the
counter weight suspended permanently into the
Specifications : oil tank. The horizontal movement i.e, displacement
Telescope focus range 250 to 500 mm is monitored using a T-square or a vernier
Measuring range 75 mm Microscope.

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Installation :
INVERTED PENDULUM
The pendulum wire is installed in a vertical borehole
Purpose : or duct. The radius of the borehole or duct should
Inverted pendulum is used for measurement of the be greater than the anticipated movement, and
displacement of the Dam foundation. sufficient to allow unavoidable deviations from the
vertical hole. Boreholes are generally cased to ensure
Operating Principle : long term stability. In corrosive environment, the
The Inverted Pendulum is installed to provide a boreholes may be lined with PVC tubing which is
fixed datum from which the structural movements sealed at the base and filled with light oil. Grouting
can be monitored. It consists of a wire anchored in may be necessary where the lining passes through
stable ground beneath the structure, with a float broken or highly permeable ground. Inspection
fixed to its upper end. The float, which is free to galleries give access to each of the intermediate
move in a water tank, tensions the wire and keeps it reading elevations. A smooth and level concrete pad
vertical. approximately 1 m X 1 m X 10 cm thick is required
Measurements are taken at one or several as a base, for the float support frame and
elevations along the wire, readings, taken of two intermediate measuring units. The measuring units
perpendicular components of horizontal and their supports should be positioned on their
movement at each elevation. pads so that pendulum wire passes through them
Displacements relative to the wire may be as it is installed.
measured using a T-Square frame / Travelling An anchor is used to secure the lower end of the
Vernier Microscope. wire. The tubular anchor is filled with concrete on
the site, three centralizing bolts having been
Advantages : adjusted to suit the borehole diameter. Pendulum

Measuring accuracy can be greater than that wire is bolted to the anchor, the bolt passing
obtained by precise geodetic surveying. through the stainless eyelet fixture on the wire. The

Movements can be observed at frequent cord is used to take the weight of the anchor as it
intervals without repeated costly surveys. is lowered into position. A length of the cord is kept

Instrument error and ambiguities are avoided. greater than twice the depth of installation. The
cord is passed through the eye bolt on the anchor

Pendulum instruments are simple and therefore
and the free ends are tied together. The pendulum
reliable in long term use.
wire is carefully uncoiled as the anchor is lowered,
Applications : keeping the wire taut and finally securing it at the
hole collar.
In general, the Inverted Pendulum monitors the
horizontal movement. Its specific applications are
as follows:

To measure displacements in dams, dam
foundations and abutments.

To determine the structural and foundation
movements of the tall buildings.

To be used as a primary reference for geodetic
surveying.

INVERTED PLUMB LINE ASSEMBLY

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Once in position, the cord is removed and the two measuring scales. Intermediate measuring
anchor is grouted with cement mortar placed units are centralized with reference to the taut wire.
through a tremie pipe. The float unit and Each support frame should be securely bolted to
measuring unit are positioned on float support its concrete pad.
frame. Sufficient water is poured into the tank to
AIM 751 Inverted Pendulum with
raise the float approximately 50 mm. The
T Square Unit
pendulum wire is then threaded through the pulley
Specifications
on the float adjusting rod and is cramped taut,
Telescope focus range 250 to 500 mm
using two wire clamps. Excess wire is then
Measuring range ± 50 mm
removed. The adjusting rod is used to set tension
Resolution 0.01 mm
in the wire, to the required amount, ensuring that
Accuracy 0.1 mm
the float clears the base of the tank. More water is
Table size 625 mm x 625 mm
poured into the tank until float is submerged. The
Stainless steel wire 1 mm x 60 m long
water surface should be covered with a 10 mm layer
(other lengths
of oil to limit evaporation. The unit is then
available)
repositioned to bring the float to the centre of the
Wire suspension Collet on hollow
tank, checking that the wire is at the centre of the
float in tank filled with water
Suspension wt./Wire
tension 8 kgf
Tank Fiber glass :
600 x 400 mm long
Float material PVC

AIM 751 INVERTED PENDULUM

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 STRUCTURAL MONITORING

infrared transmitters and receivers are mounted. The

AUTOMATIC PENDULUM carriage is moved along a prevision track bed, using
CO-ORDINATOR a lead screw assembly. The infrared beams are
broken by the wire as the carriage moves along its
Purpose : path. The position of the carriage when the
infra-red beams are broken is measured by a Linear
The Automatic pendulum co-ordinator is used to Potentiometric Transducer.
record the dam deflection and base movement The use of this remote co-ordinator does not
automatically. preclude the use of other mechanical or optical
Applications : measuring equipment.

Arch concrete dams Where tilt at a number of elevations is required, these

Gravity concrete dams co-ordinators can be linked to a central data

Shafts acquisition system, and profiles generated from the

Caverns recorded data. Interrogation of these units can be

Tall structures performed either by using a portable dedicated

Retaining walls readout/logger or by hard wiring acquisition system.
Hanging and Inverted Pendulums are used to The co-ordinator should always be oriented with the
measure the tilt or rotation of the large structures. X axis in the direction of expected movement and,
Each employs a tensioned, stainless steel wire and to standardise the data output, the orientation of
effects of the earth gravitational forces guarantee a the units should be common for all locations.
perfectly vertical line between a fixed point and a Data from the co-ordinator is displayed by the
tensioning mechanism. The hanging pendulum has readout unit in comma separated engineering units
a fixed point high up in the structure and heavy which can be uploaded to spreadsheets or data.
weight is used to generate the tension. The weight
is usually submerged in a fluid to damp movements AIM 758 Automatic Pendulum
that may be caused by the currents of air. The Co-ordinator
inverted pendulum has a fixed point at, or below Accuracy : 0.1 mm
the base of the structure and employs a large float Repeatability : 0.05 mm
in a water filled tank, to generate tension in the wire. Resolution : 0.05 mm
Measurement of the position of the vertical wire, Range X direction : ± 50 mm
relative to the structure allows rotation or tilt, to Range Y direction : ± 20 mm
be calculated.
AIM 876 Readout/Logger
Pendulums are often installed in remote
Designed to monitor and record the readings of
structures such as retaining walls and dams. Since
both x - y coordinates at predetermined intervals.
these instruments will often form part of an
instrumentation scheme, for safety purposes, AIM 8760 WINSID Data Presentation and
regular monitoring is essential. Management Software.
This non-contact type Automatic Remote
Monitoring Pendulum Coordinator is designed
to provide monitoring teams with a simple and
an effective means to electronically log the tilt or
rotation of structures.
The unit consists of a 12 volt motor and gearbox
assembly, all housed in a waterproof case, and a
precision machined carriage onto which 2 pairs of
accurate infrared transmitters and receivers are
mounted. The carriage is moved along a precision
machined carriage onto which 2 pairs of accurate AUTOMATIC PENDULUM CO-ORDINATOR

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Can be coupled to vibrating wire transducer and

BORE HOLE EXTENSOMETER
read out to give continuous or remote reading.
Purpose : For installation in boreholes or drillholes at any
Bore Hole Extensometer is used for measuring and orientation or alternatively it can be cast in concrete,
monitoring of rock and soil movements in dams surface mounted or buried in the fill. Hole diameter
underground activities, slope stability etc. 38 to 100 mm depends on the number of rods.
Rod lengths in excess of 100 m may be used if
Operating Principle :
installation problems are encountered and
The single rod extensometer employs a rod, borehole stability is to be ensured. Reset range
anchored at one end of a drill hole, passing into a
adjustment up to 150 mm is possible. All
reference tube fixed in the hole collar. Relative
components are corrosion, blast and vibrations
movement between the end anchor and the
proof.
reference tube is measured with either a dial depth
gauge or an electrical transducer, inserted through Applications :
the reference tube, registering on to the free end
The monitoring of rock and soil movement
of the rod. A range adjustment screw fitted to the
include:
end of the rod extends the reading range beyond

Relaxation of rock around the tunnels and other
that of the dial gauge. Multiple rod installations
underground openings.
monitor displacements at various depths using
rods of varying lengths. Several single rod units
Foundation settlement.
may be installed in close proximity in drillholes of
Monitoring of subsidence.
smaller diameter. Alternatively, several rods may
Control of natural and cut slopes, quarry and
be installed side by side in a single larger hole. Each mining excavations.
rod is individually isolated by a close fitting plastic

Displacements of retaining walls, bridge piers
sleeve. The complete assembly is grouted in place,
and abutments.
fixing the anchors to the rock or soil but allowing
free movement of each rod within its sleeve. A
Monitoring of In-situ tests.
multipoint reference housing receives all rods from
Installation of Multiple Rods in downholes :
one drill hole installation. Facilities are available for
manual or remote readout. A visual alarm system A shallow recess is excavated to the required
to give warnings of excessive movements is also reference level and the datum/ tube plate, which
available, which can also be used for indicating is supplied with the AIM 76103 reference head is
when a reading is to be taken. Rod extensometer set with three ragbolts, either in a concrete plug or
units can be surface mounted to measure by pre-drilling holes for the ragbolts using resin
displacements across tension cracks or joints or can cement to form a secure bond at the base of the
be buried in fill or cast in concrete. recess. The reference level should be beneath the
influence or irrelevant superficial movements, for
Advantages :
example due to temperature variations and surface

Reliable, accurate, simple to install and read. traffic. Each anchor should when feasible, be a

Free from creep, kinking and other inaccuracies whole number of metres beneath the datum/tube
associated with the use of tensioned wire plate. The hole is drilled at least 50 cm beyond the
systems. deepest anchor. Casing, if used, must be removed

The simple single rod instrument is ideal for before the installation. The sleeve guide plate,
installation in small drillholes as a safety supplied with the reference head, is installed on
monitoring during construction. the ragbolts and sleeve support / clamp unit is

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secured to the plate. One length of protective sleeve The above procedure may be varied to suit site
is secured to the anchor unit. The assembly is requirements. For example shorter lengths of
inserted through the sleeve guide plate and clamp extensometer may be pre-assembled as also the
unit. Further lengths of sleeves are added using drill hole may be filled with grout prior to the
PVC cleaner and adhesive. The sleeve is clamped installation. In soft ground or when the
as each joint is made, until the anchor reaches the extensometer is to be operated in compression
required depth at the base of the hole. Excess sleeve rather than extension, it may be necessary to grout
length is left protruding beyond the clamp unit. anchors one by one, filling the intermediate lengths
Sleeve may be greased to reduce adhesion with the of borehole with a more compressive material such
grout. A grout tremie pipe is inserted to the base of as bentonite or sand.
the hole, followed by the remaining anchors and
Installation of single rod units :
sleeves. Grout is poured or pumped down the
tremie pipe, which is then withdrawn and cleaned. Single rod extensometers are available with
The grout should be as deformable as the ground. groutable, resin bonded or expanding the shell
The final grout level should be within 50 cm anchors. These may be installed with groutable or
beneath the guide plate. expanding shell reference tubes.

When the grout has set, the sleeve support/clamp

plate is removed and the sleeves cut back, to leave
approximately 20 mm protruding from the guide
plate. Lengths of extensometer rods are then
inserted into the sleeves, using metal adhesive
coupling.
Adhesive is not applied to the first rod end which
receives the anchor. The rod string is supported,
when making the joints, by inserting a pin through
the coupling tommy bar hole.
When the required rod length has been inserted
and located on to the anchor thread, the final rod
at the guide plate is marked level with the
protruding sleeve end. The rod string is then
unscrewed from the anchor and with drawn
sufficiently to grip with molegrips for cutting and
re-threading with the tap or die to accept range
adjustment unit. The rod length depends upon
the anticipated ground movement and range
adjustment unit selected. The range adjustment is
fitted and the rod string re-installed using rod
locating tool. The adjusting screw is roughly set
using range adjusting tool. When the remaining
rods have been installed, the reference housing is
bolted in place and final range adjustments are
made to obtain base reference readings using dial
depth gauge or a transducer.

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Surface Monitoring : length, and rods range adjustment units and

To monitor tension cracks and joints a single rod is reference head fitted, as described above for
assembled, using standard rods and sleeves with downhole installations.
single rod extension head and anchor system to Remote readout installation :
form a surface mounted assembly.
Displacement transducers are fitted into the bushes
Installation of Multiple rods in up holes : in the reference heads when remote readout is
The procedure for upward inclined installation of required. A suitable protective head with cable
multiple rod units is similar to that described glands are then used.
above, but with one rod position in the sleeve guide
AIM 761 Bore Hole Extensometer
plate being used for a grout return/air bleed pipe.
The datum/tube plate and ragbolts are sealed and AIM 76101 Single Point Reference
bedded to the rock surface using resin cement. The Head for Dial Gauge
sleeve guide plate and sleeve support/clamp unit Number of rod : 1
are secured to the plate. Lengths of grout return/ Minimum holedia : 38 mm
air bleed pipes are joined by a cleaner & adhesive
and inserted through the sleeve and a guide plate AIM 76102 Single Point Reference
until the top of the hole is reached; the pipe is then Head for Vibrating Wire
withdrawn approximately 50 mm and clamped. Transducer
The top of the pipe should be at least 50 cm above AIM 76103 Multiple Point Reference
the deepest anchor. Anchor and sleeve are installed Head for Dial Gauge
as described for down-hole installations.
Number of rods : 2 to 5
A 50 cm long primary grout stem provided with Minimum hole dia : N X (75.3 mm)
each reference head is screwed into the central hole
of the sleeve guide plate. The sleeve guide plate, AIM 76104 Multiple Point Reference
together with the clamp unit, sleeves,anchors and Head for Vibrating Wire
grout pipes are lowered from the hole by removing Transducer
the ragbolt nuts. With the assembly supported, AIM 76111 End Anchor
resin cement is packed around the sleeves and AIM 76114 Dial Depth Gauge
guide pipes. The assembly is bolted back onto the Range : 50 mm
ragbolts and approximately 3 litre of grout is Sensitivity : 0.01 mm
pumped through the primary grout stem.
The grout pump pipe is removed, allowing excess
grout, above the primary grout stem, to drain. The
remaining 50cm column of grout behind the sleeve
location plate is allowed to set to form a strong
grout plug for final grouting of the hole. The grout
pump is reconnected and the hole grouted until
grout flows from the return/air bleed pipe.
On some shallow and horizontally upward inclined
holes it may not be necessary to form the primary
grout plug since the pressure of grout will be
relatively low.
When the grout has set, the sleeves support/clamp SINGLE POINT BORE HOLE EXTENSOMETER
plate is removed, sleeves and grout pipes cut to

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AIM 76115 Portable Calibration Unit AIM 76107 Extensometer Rod, 3 m long
Dial Gauge with coupling.
AIM 76116 Vibrating Wire Displacement AIM 76108 Protective Sleeve, PVC, 1 m long.
Transducers AIM 76109 Protective Sleeve, PVC, 2 m long.
Range : ± 25 mm AIM 76110 Protective Sleeve, PVC, 3 m long.
Sensitivity : 0.01 mm AIM 76112 Range Adjustment Unit,
150 mm, with adapter sleeve.
Over Range : 150 % of range
AIM 76113 Range adjustment tool.
Accuracy : ± 0.5 mm or better
AIM 76119 Installation Tool Kit.
Material : Stainless Steel
AIM 76120 PVC Adhesive.
Coil Resistance : 140 - 160 Ohm
AIM 76121 Metal Adhesive.
Operating : – 10° to +70°C
AIM 76122 PVC cleaner, 0.5 litre.
Temperature
Thermister : YSI - 44005 or equivalent, AIM 76123 Sleeve Support / Clamp Unit.
3 k Ω @ 25°C AIM 76124 Installing Adaptor and Handle.
Sealing : Hermetically sealed with inert AIM 76125 Grout Pipe.
gas, meets IP - 68, weather AIM 76126 Air BIeed/Grout Return Pipe.
protection clause AIM 76127 C- shaped Hydraulic End
Cable : 4 - Core shielded, 1 m Anchor for rock.
AIM 76128 Nylon tube 2 x 4mm dia
Potentiometric type sensors can also be supplied.
for hydraulic anchor.
AIM 76117 VW Displacement Transducer
AIM 76129 Hydraulic Hand Pump.
Range : ± 50 mm
Sensitivity : 0.01 mm AIM 76130 Manifold with 5 outlets and
Over Range : 150% of range isolating valve to suit 5 hydraulic
anchors
Accuracy : ± 0.5 mm or better
Material : Stainless Steel
Coil Resistance : 140 - 160 Ohm
Operating : – 10° to +70°C
Thermister : YSI - 44005 or equivalent,
3k Ω @ 25°C
Sealing : Hermetically sealed with inert
gas, meets IP - 68, weather
protection clause
Cable : 4 - Core shielded, 1 m
Potentiometric type sensors can also be supplied.
AIM 76105 Extensometer Rod, 1 m long
with coupling.
AIM 76106 Extensometer Rod, 2 m long AIM 761 BOREHOLE EXTENSOMETER WITH ACCESSORIES
(MULTI - POINT)
with coupling.

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TAPE EXTENSOMETER
Deformation of excavation in underground

power houses, caverns and adits.
Purpose :
Displacement of retaining walls, cuttings, bridge
Tape Extensometer is used for measuring and piers, arches and abutments.
monitoring of surface, lateral movements, radial
Stability of concrete structures and buildings.
movements and convergence of tunnels, shafts, Performance :
lining and caverns by measuring convergence Measuring range of standard instrument is 1 m to
between pair of reference studs. 30 m. Overall measuring repeatability of 0.1 mm
with an operator experience. Robust and proof
Operating Principle :
against mechanical damage under reasonable field
This instrument, which is portable, measures conditions. Average reading takes only 2-3 minutes
displacement between pairs of reference eye bolts, by a single operator.
grouted into shallow drill holes in the structure or
excavation.
The reference points may be permanently fixed or
may be demountable. The tape extensometer unit
comprises of a stainless steel measuring tape with
equally spaced precision punched holes. The fixed
end of the tape is fitted to the tape reel integral
with the lightweight body, which has a location
hook identical to that on the free end of the tape.
The body incorporates a tape tensioning device, AIM 771 & 772 TAPE EXTENSOMETERS
coupled to a sliding scale and dial gauge
Installation of reference points :
arrangement. The location pin is engaged into the
Reference points are usually installed in
appropriate tape hole and is secured with the
predetermined pattern. For example, radially or in
retaining clip. To adjust the tape tension, the
a triangular grid around a tunnel or shaft for
knurled collar is rotated until the white lines on
monitoring convergence of the linings or rings.
the face plate and internal spring anchor block are
Convergence reference studs with anchors AIM
precisely aligned. A reading is taken by noting the
77102 to AIM 77104 supplied complete with
visible pin hole position on the tape at the
rugged anchors. Anchor lengths are selected to suit
instrument nose and adding to it the reading on
the nature of the material in which they are to be
the internal sliding scale and dial gauge. The
installed. The anchor holes are drilled and the
resolution of the dial gauge is 0.05 mm.
anchors installed, using a high strength cement or
Advantage : resin grout.

Simple, reliable and easy to read, provided with Demountable reference points are used when
positive tape tensioning. eyebolts protruding excessively are unacceptable

Can be operated by one person and read from or to avoid damage by site traffic. The demountable
one end only. reference points are screwed on to the anchors,

Measurements from 1 m to 30 m. which are installed in drill holes of 25 mm or larger
(longer tapes are also available on request). size and are fixed in place with cement or resin
grout. A protective cap AIM 77105 is fitted to the
Applications :
anchor, before installation, to prevent grout fouling
The measurement of surface movements include: the threads. Errors due to change in temperature

Radial movements and convergence of tunnels, may be corrected by comparing readings on the
shafts and linings. portable calibration bar AIM 77101.
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AIM 771 Tape Extensometer, AIM 77155 Replacement Steel Tape, 20m for
with Vernier Dial Guage Range 20 m tape Extensometer Unit. The
AIM 772 Tape Extensometer, with Stainless steel tape is precision
Vernier Dial Guage Range 30 m punched and graduated through its
length
AIM 771-1 Digital Tape Extensometer, with
Digital Dial Gauge, Range 20 m AIM 77255 Replacement Steel tape, 30m for
tape Extensometer Unit. The
AIM 772-1 Digital Tape Extensometer, with Stainless steel tape is precision
Digital Dial Gauge, Range 30 m punched and graduated through
Installation Accessories : out its length.

AIM 77101 Portable Calibration bar for Optional Extra :

checking tape extensometer unit AIM 77106 Demountable Reference Stud,
before and after each set of alternative to AIM 77102 and AIM
measurements. Comprising of 77104, Convergence Reference
epoxy painted aluminium alloy Stud, for use with tape
frame with two eye bolts mounted Extensometers comprising of
at 1 m gauge length. stainless steel eye bolt with
AIM 77102 Convergence Reference Studs, internally threaded body to fit on
130 mm overall anchor length, for the anchor system. Overall
use with Tape Extensometers AIM dimension 60 mm long X 30 mm
771 and AIM 772 comprising of a dia (protection cap is recommended
stainless steel eye bolt mounted on to protect eye bolt when not in use).
a 20 mm diameter cadmium plated
steel ragbolt anchor
AIM 77103 Convergence Reference Studs,
same as AIM 77101 but with 28
mm anchor length.
AIM 77104 Convergence Reference Studs,
same as AIM 77102 but with 500
mm anchor length
AIM 77105 Protective Cap, to fit on reference
point, comprising of plastic cap AIM 77103, 4, 5 TYPICAL CONVERGENCE
with Integral retaining strap and MEASUREMENT SYSTEM FOR TUNNELS

ring. The cap is a push fit on the eye

bolt
AIM 77107 Resin Cement, to fix anchor in drill
hole, comprising of twin pack,
polyester resin and catalyst
hardener
AIM 77108 Cartridge Injection Gun Kit
Spares:

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with 0 to 5 mm grain size is recommended. If installed

VIBRATING WIRE SOIL in a coarse rockfill material, a filter fabric should be
EXTENSOMETER placed between the sand and the rockfill material to
prevent large stones from penetrating into the fine
Purpose : material surrounding the instrument.
The cable should be burried in a cable trench, parallel
Soil Extensometer is used for measuring and
to the extensometer trench. Normally, cables from
monitoring internal deformation and cracking of an extensometer chain are connected to a multicable
dam embankment ,natural and cut slopes.. in a special embankment junction box. The
multicable is then routed to the monitoring
Operating Principle :
equipment.
The basic principle of the Vibrating Wire Extensometer The extensometers are usually installed horizontally
is that the change in the natural frequency of a stretched and laid parallel to the crest to measure strains,
wire depends on the change of tension in the wire. In longitudinal to the axis of the dam. The extensometers
this instrument, one end of the wire is attached to are linked together, in 4 to 12m long sections by
moveable head of the extensometer by a steel spring. A universal joints, extension pipes and anchor plates to
displacement of the extensometer is thus transformed
form continuous extensometer chains of varying
to a variation in tension of the spring and also in the
length depending on the geometry of dam.
vibrating wire. Therefore, the frequency of the wire is a
measure of the displacement between extensometer and AIM 776 Vibrating Wire Extensometer,
anchor. The difference of the squared frequencies is
proportional to the displacement. 150 mm
Measuring Range : 150 mm
Advantages :
Linearity : 1 % of FS or better

Rugged construction and reliable.
Hysteresis : 2 % of FS or better

Long term stability.
Calibration : Individual - with 1/100 mm resolution

Accurate, simple to install and read.
Material : Cadmium plated steel

Suitable for remote reading of displacement at Cable : 4 - Core shielded, 1 m
inaccessible locations.

Range is as high as 200mm. AIM 777 Vibrating Wire Extensometer,

Reinforced cable and reliable signal transmission. 200 mm

Can with stand water pressure upto 20 bar. Same as AIM 776, but with 200 mm range
Applications : Accessories :

For monitoring internal deformation and AIM 77601 Extension Steel Rod, galvanised,
cracking of dam embankment near the abutments. 25mm diameter

For monitoring settlements, heave and lateral AIM 77602 Anchor Plate, 300mm x 300rnm x 10mm
movements in the foundation and embankments. AIM 77603 Rock Anchor System, with

For monitoring displacement of retaining walls, expansion bolt, washer connector &
bridge piers and abutments. ball connection

For monitoring movement of natural and cut AIM 77604 Protection Tubing, PE, ID 63 mm
slopes quarry and mining excavations.
Installation :
The vibrating wire extensometers are installed in the
embankment on a level surface, either in an excavated
trench, 1 m deep and 0.5 to 1 m wide or on a
compacted bedding, 1 to 2 m wide. If installed in
the impervious core of a dam, 100 to 150 mm layer
of screened core material should be placed beneath
and above the instrument; otherwise a sand material AIM 776, 875 VIBRATING WIRE EXTENSOMETER

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Low volume change and slender profile arching

VIBRATING WIRE and stress concentrations are limited.
PRESSURE CELLS
Overvoltage surge protector fitted to protect
against electrical damage.
Purpose :

Suitable for remote reading, scanning and data
Pressure cells are used for measurement and
logging.
control of pressure /stress distribution with in
embankment and dams. And also used in Applications :
measurement of contact pressure on retaining The measurement and control of pressure include:
walls /diaphragm walls , piers and abutments and

Total pressure and stress distribution within
linings of underground excavations.
embankment and dams.
Operating Principle :
Contact pressure on retaining and diaphragm
The cell consists of a circular or rectangular flat walls, piers and abutments.
jack formed from two steel plates welded

Foundation bearing pressure.
around the periphery. The narrow gap between
the plates is filled with fluid of comparable
Pressure on and within linings of underground
deformability to that of the ground; oil for use excavations.
in soil; mercury for rocks. The cell is connected
Stresses in the rock walls of unlined caverns and
to a vibrating wire pressure transducer by a tunnels.
short length of steel tubing, forming a closed
hydraulic system. Both cell and transducer are Installation in Soil and Rockfill :
embedded in the structure to be monitored. An Oil filled pressure cells measure total pressure. The
armoured, screened cable connects the effective (intergranular) pressure at the measuring
transducer to a terminal unit or directly to the location can only be determined, if each cell is
portable readout unit. accompanied by a piezometer. Cells may be
installed individually but frequently they are
The vibrating wire pressure transducer
grouped in clusters of four or five, each cell at a
connected to the cell consists of a vibrating steel
different orientation. An excavation to
wire, one end of which is attached to the center
accommodate a cluster of five cells will have
of a circular pressure sensing diaphragm and
dimensions typically 3 m x 8 m x 1 m deep, with
the other end secured to the top of the
side slopes not steeper than 1 in 5 to avoid stress
transducer housing. Fluid pressure applied to
concentrations.
the diaphragm causes deflection of diaphragm,
with consequent change in the tension of the The base of the excavation should be compacted
gauge wire and its resonant frequency. Thus, and levelled. A trench, 1 m deep and 60cm wide
the frequency of the gauge wire is a measure of to receive the tubes enters the excavation at mid
the deflection of diaphragm, which is length. Cells AIM 78101 and AIM 78102 are
proportional to the pressure change. individually installed in small pockets at the base
of the excavation.
Advantages :
They should be separated from each other by

Accurate, robust, reliable with long term
atleast 1 m. Cell locations are carefully marked out,
stability.
the pockets hand dug and trimmed. Protruding

Transducer design prevents case stress affecting stones are removed and the holes filled with
the readings. compacted stone-free soil. In rock fill, the pocket
for each cell is larger than the soil and is backfilled

Accuracy unaffected by cable length.

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with thoroughly compacted material of Measurements in Rock and Concrete :

progressively smaller size, until the material in Vibrating Wire Pressure Cells installed in concrete
contact with the cell is of grain size less than 5mm. or shotcrete are liable to expand due to heating by
A shallow channel is excavated to accommodate the cement, as it sets. They subsequently contract
the tube and transducer. The tube may be bent to to leave a gap between the cell and concrete. This
facilitate installation, with care taken to avoid may be overcome by using handpump connected
kinking or straining of the weld where it enters to the compensating tube on cells AIM-78602 to
the cell. Cells are connected in turn to the readout AIM 78604. Cells are usually secured to the
unit. Cell pressure should be read at time of reinforcement before the concrete is placed. The
installation. compensating and transducer tubes may be bent
The cell is positioned in its pocket and checked for to facilitate installation, taking care to avoid kinking
alignment and level. The pocket is backfilled in or straining of the welds.
horizontal layers, using wherever possible the Cells placed at a concrete-rock interface should be
excavated soil, stone-free and at optimum water embedded in a thin pad of lean mortar. If high
content. Each layer should be firmly stamped while contact pressures are anticipated these interface
ensuring that the cell remains in position. Following cells need not employ a compensating tube. In a
installation, the pressure in each cell is again tunnel, for example, the cells are usually installed
checked. Cables are bunched together and snaked in groups of two or three to measure radial,
in the lead-in trench, protected above and below tangential and axial pressure. Several groups of cells
with 15cm of stone-free sand or clay. The main are installed around an instrumented section to give
excavation and trench area is backfilled using hand the distribution of pressures on and within the
operated compactors. No large machine should be lining.
allowed over the area until at least 1 m of
thoroughly compacted material has been placed. Installation of Cables and Terminal
Equipment :
Interface between Concrete and Soil : Pressure cell cables must be protected from
Pressure cells AIM 78103 and AIM 78104 are mechanical damage. In earthworks they are
designed for this application, with a rigid back plate grouped losely at the base of trench, approximately
and one active face. The cell is installed so that the 60cm deep, protected above and below with 15cm
exposed active face is flushed with the interface of stone-free sand or clay. In other installations the
between concrete and soil, either by securing the cables may be run in protective conduit or may be
cell to the formwork or by fixing a wooden disc to
form a recess in which the cell is subsequently
embedded. Diaphragm wall installations may
incorporate cells located in the reinforcement steel
cage alongwith small expandable hydraulic jacks
and reaction struts.
The cage is lowered into the slurry trench, the cells
are jacked firm against the trench walls and
concrete is then poured. Cells at the base of
concrete footings are tied to the soil or rock
foundation. Care should be taken to avoid air
pockets and to retain the cell firmly in contact with
the ground during concreting. AIM 78101, 78602, 875 PRESSURE CELLS

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cast into concrete or protected with shotcrete. The overvoltage surge arrester. Oil filled pressure cells
cables should be looped where they cross an are used for embedment in soil or rockfill.
interface and at joints. This reduces strain in the
Measuring Range: 5 to 150 bar
cables and joints due to differential movement.
(5, 10, 20, 40, 60, 100 or 150 bar)
When there are sufficient pressure cells to justify
Accuracy : ± 1 % FS
use of an instrument house, the cables are led
through an entry duct which is cast into the Resolution : 0.01 % of range
concrete floor, and connected to a Switch Box or Coil Resistance : 140 - 160 ohm
Terminal Unit attached to the wall. Readings are Material : Stainless Steel
taken by connecting a flylead from the portable
Operating : – 10° to + 70° C
readout unit to a common plug-in connection and
Temperature
by switching to respective channels.
Thermister : In built YSI - 44005 or
Specifications : equivalent, (3k Ω @ 25°C).
Sealing : Hermetically sealed with inert
All pressure cells are connected to a vibrating wire
gas, meets IP - 68, weather
transducer. The stainless steel transducer
protection clause
incorporates pluck and sensing unit with
Cable : 4 - Core shielded, 1 m

Cat No. AIM 78101 AIM 78102 AIM 78103 AIM 78104 AIM 78602 AIM 78603 AIM 78604

Cell 200 dia 300 dia 240 dia 345 dia 100 x 200 150 x 250 200 x 300
Dimension
(mm)

Active 180 dia 280 dia 180 dia 280 dia 90 x 190 140 x 240 190 x 290
Dimension
(mm)

Overall 6.4 6.4 12 12 6.4 6.4 6.4

Thickness
(mm)

Cell Oil Oil Oil Oil Mercury Mercury Mercury

Filling

Use Soil and Soil and Concrete Concrete Rock, Rock, Rock,
Rock fill Rock fill Soil Soil Concrete Concrete Concrete
Interface Interface Shortcrete Shortcrete Shortcrete

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 STRUCTURAL MONITORING

require jacking pressures. The ram and cell

JACK OUT PRESSURE CELL assembly is installed into the reinforcement cage
with the cell and reaction plate positioned on either
Purpose :
side of the cage with the ram passing through the
Jack out pressure cells are used for measuring and reinforcement. The assembly is loosely supported
recording stressing in the rock walls of unlined in the cage by tie wires.
caverns/ tunnels, retaining walls piers and abutments. When the cage is lowered into the slurry filled
trench to the specified level, the ram is hydraulically
Operating Principle : pressurised to force the cell and reaction plate
When an external pressure is applied to the outwards to bear onto the sides of trench. The ram
membrane, to which the stretched vibrating wire pressure is increased to ensure good embedment
is rigidly attached, it causes a change in tension in into the trench wall. The swivel joint behind the
the wire due to the deflection of membrane. This cell allows for some misalignment. Ram pressure
causes change in the natural frequency of vibration. is maintained throughout the pour and curing of
The change in pressure acting on the membrane the concrete.
surface is proportional to the difference of the
squared frequency of vibration for the AIM 787 Jackout Pressure Cell
corresponding pressure. The frequency signal is Range : 5 - 40 bar, (5, 10, 20 & 40 bar)
transmitted by the electrical cable to a readout System accuracy : < ± 1% FS
instrument. Resolution : 0.01 % of range
Coil Resistance : 140 - 160 Ohm
Advantages :
Cell OD : 240 mm

Accurate, robust, simple operation with long Cell, active dia : 180 mm
term stability.
Overall thickness : 12 mm

Portable readout units may be used in
Overall length : 240 mm
conjuction with piezometer and settlement cells.
(including transducer)

Suitable for remote reading and data logging. Sealing : Hermetically sealed with inert
Applications : gas, meets IP - 68, weather
protection clause

Contact pressure on retaining and diaphragm
walls, piers and abutments. Cable : 4 - Core shielded, 1m

Foundation bearing pressures. AIM 78701 Jackout Pressure Cell

Pressure on and within linings of underground without jack
excavations. Installation Accessories :

Stresses in the rock wall of unlined caverns and AIM 78701 Hydraulic Hand Operated Pump
tunnels. for AIM 787
Installation : AIM 78702 Nylon Tube, 2m x 4 mm dia
The cell consists of a circular steel flat jack formed
from a thin pressure plate welded around its
periphery to a thick back plate. The narrow gap
between the plates is filled with deaired oil. The
back plate of the cell is connected to a vibrating
wire pressure transducer. The cell is mounted onto
a hydraulic ram via a ball and socket joint. The
other end of the ram has a reaction plate of similar
diameter to the cell.
Note : The pressure cell can be supplied without
the hydraulic ram for applications which do not
AIM 787 JACKOUT PRESSURE CELL

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Interpretation of temperature related stress and

VIBRATING WIRE volume change in dams.
TEMPERATURE GAUGE
Air temperature measurement on structure
surface.
Purpose :
Installation :
Temperature meter is used for measurement and
monitoring of temperature changes (rise/fall) in Temperature gauges can be either embedded or
concrete soil and rocks. surface mounted. Embedment of the Temperature
Gauge is relatively simple, since orientation is not
Operating Principle : critical and the instrument itself is ruggedly
The temperature gauge consists of a vibrating wire, constructed. These Temperature Gauges are
stretched along a rigid base with differential embedded in the body of the dam to measure the
thermal expansion characteristics. Changes in the temperature of the concrete. The temperature
temperature will therefore cause changes in the gauges are also placed near the upstream face to
vibration frequency. The difference in the square measure temperature of water. These are placed
of the frequency is proportional to the change in flush with the upstream face, with proper
temperature. These frequencies are read by the anchorage and protection. Thermal mass requires
vibrating wire readout unit. Measurements are minimum 10 minutes to achieve steady state. The
unaffected by line faults and line thermal expansion readings should therefore be taken after a lapse of
coefficient. The vibrating wire is encased in a at least 10 minutes.
robust watertight stainless steel tube, designed for
AIM 801 Vibrating Wire Temperature
direct embedment in concrete.
Meter
Advantages : Range : – 10° to + 70°C

Accurate, robust, high resolution and long term Accuracy : ± 0.5 % of FS
stability.
Resolution : 0.03°C

Suitable for remote reading, scanning and
Coil Resistance : 140 - 160 ohms
data logging.
Material : Stainless Steel

Outer body of stainless steel
Sealing : Hermetically sealed with inert

Fast response to temperature changes.
gas, meets IP - 68, weather

Accuracy unaffected by cable length. protection clause

Common portable readout unit can be used Cable : 4 - Core shielded, 1 m
with all vibrating wire type instruments.
Length : 130 mm
Applications : Diameter : 16 mm
The measurement of temperature in concrete, soil
and rock include:

Monitoring of temperature rise during the
curing of concrete.

Soil and rock temperature adjacent to ground
freezing operations and liquid gas storage tanks.

Interpreting temperature effects on other
installed instruments.

Measurement of water temperature in
reservoirs and boreholes. AIM 801, 875 VIBRATING WIRE TEMPERATURE GAUGE

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Features :
VIBRATING WIRE BOREHOLE
The Vibrating wire technology has an unique
STRESS METER advantage of providing a frequency based output
signal which can travel unaffected over long
Purpose :
distances. This technology is used in the
Borehole stress meters are used for measuring and
Stressmeter which offers the following features:
monitoring stress changes in underground coal
mining (Long walls) operation.
Direct measurement of stress change in solids.

Wedge/Platen assembly for hard and soft
Description : materials.
The Stress meter is quite small with a length of

High stress and load sensitivity virtually
about 41 mm and a diameter to fit in an E size hole
insensitive to temperature changes.
(38mm). It is composed of a hollow cylindrical
body sustaining a piano wire across the diameter.
High temperature model, stable at 200°C.
Both ends are sealed under vacuum with small cans
Stable frequency output signal.
that are vacuum sealed. The body is electroplated
to resist corrosion to ensure long term stability in
Digital reading for automatic logging.
harsh environments. For excitation and reading
Vacuum sealed.
purposes, a coil/magnet assembly and a thermistor

Electroplated body to prevent corrosion.
are encapsulated in one of the cans and are
connected to a 4 conductor shielded electrical cable. Applications :
A two part wedge/platen assembly completes the U.S. Bureau of Mines developed the vibrating wire
Stressmeter. Sitting on a flat made onto the stressmeter for the purpose of monitoring stress
cylindrical body of the stressmeter, this assembly change in underground coal mining-operations.
is used to pre-stress the Stressmeter against the Its use has then been extended to hard rock and
borehole wall at the time of installation. The wedge/ concrete structures. It also serves as a load cell when
platen assembly can take two configurations incorporated between steel members.
depending on the installation being made either
The Stressmeter measures stress or load in
in hard rock or soft rock. In softer materials such

Mines, roof, wall and pillar.
as coal, special wide platens are used to lower the
contact stresses on the borehole wall.
Around tunnels and within linings.
Stress variations in the host medium will deform
In underground storage chambers.
the Stressmeter changing the wire tension and
In concrete structures.
consequently its resonant frequency. When a
reading of the Stressmeter is taken, the readout
In foundations bearing plates and between
unit generates plucking voltages at variable steel girders.
frequency in the coil/magnet assembly, forcing the
Installation :
wire to vibrate. In turn, this vibration generates
AC voltages in the coil. The readout then selects The Stressmeter is set in a “E” size hole (38 mm
the frequency corresponding to the peak voltage, dia) 42 boreholes preferably diamond drilled to
that is the resonant frequency of the wire and provide proper sealing of the gauge against the
displays the period. Changes in the frequency or rock. When percussion drilling is done, it is of
period of vibration are correlated to stress changes. utmost importance to incorporate a reaming shell
behind the bit to obtain a smooth surface against
which the gauge will be wedged.

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The wedge / platen assembly can be activated from AIM 802 Vibrating Wire Borehole
the bore hole collar either with a manual or Stressmeter
hydraulic tool depending on the depth of Range : 70 Mpa - compression
installation. In the first case, depth of the order of 3 Mpa - tension
20 meters can be reached.
Operating : – 10° to + 70°C
The hydraulic system permits deeper installations tempature
reaching 50 meters.
Coil Resistance : 140 - 160 Ohms
The Stressmeter being a uniaxial device, several
Max. depth of : 50 m
units can be installed in series to resolve the change
Installation
in thebiaxial stress field (minimum of 3
measurements) at a particular location. Under good
conditions, it is possible to recover the Stressmeter
AIMthe
from 801borehole.

Although the Stressmeter is mostly installed in

bore holes, it can also be used advantageously as a
load cell for load monitoring within a metallic
structure.

AIM 801 BOREHOLE STRESS METER

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 STRUCTURAL MONITORING

and a waterproof displacement transducer of

VIBRATING WIRE JOINT required range.
METER The target and transducer are embedded in adjacent
pours of concrete. The target along with the Nylon-
Purpose : PVC housing is first embedded in one pour up to
Vibrating wire joint meters are used for measuring the O-ring groove by the construction joint. The
and monitoring of opening/closing of joints between tranducer is then slipped in through the socket at
concrete dam blocks, tunnel shaft linings etc. the outer end of the housing as shown in drawing
Operating Principle : and set at mid point by observing reading on the
indicator. The transducer is fixed in compressed
The basic principle of Vibrating wire gauge is that
position through the grub screws provided in the
the change in natural frequency of a stretched wire
socket and embedded in the second pour.
depends on the change of the tension in the wire.
In this instrument, one end of the wire is attached The housing has a very thin section at the joint,
to the moveable head of the joint meter by a steel which breaks when the joint opens, allowing free
spring and other end to a fixed point. The movement of the target and the transducer. The
displacement results in variation in tension of the target plates can accommodate up to 20mm of
spring and of the vibrating wire. The change in shear movement in any lateral direction without
frequency of the wire is a measure of displacement affecting the reading.
between joints. The difference of square of
AIM 806 Vibrating Wire Joint Meter
frequencies is proportional to the displacement. The
frequency readings are taken by the Vibrating Wire Range : ± 25 mm
Readout, which is connected to the gauge by cables. Accuracy : ± 0.5 % FS
Over range : 150 % of range
Advantages : Sensor Diameter : 30 mm

Accurate, robust and long term stability. Housing Diameter : 100 mm

Accuracy unaffected by cable length. Coil Resistance : 140 - 160 Ohm

Common readout unit for all vibrating wire Operatingtemp. : – 10 to + 70° C
type instruments. Material : Stainless Steel

Wateproof and sealed upto 7 bar pressure. Sealing : Hermetically sealed with

Easy Installation : Installation is extremely inert gas, meets IP - 68,
simple. The transducer can be simply screwed weather protection clause
through Grub screws at the required Thermister : Inbuilt YSI - 44005 or
compression by noting its reading on the equivalent, (3k Ω @ 25° C)
indicator set in the engineering unit mode Cable : 4 - Core shielded, 1 m

High Voltage Protection : Gas discharge tube
AIM 807 Vibrating Wire Joint Meter
assures lightening and surge protection.
Same as AIM 806 but with following specifications
Applications :
Range : ± 50 mm
Vibrating Wire type Jointmeter is used for
Length : 685 mm

Monitoring of movement at joints between
concrete dam blocks, tunnel, shaft linings
masonary structures and bridge construction.

Monitoring of superficial cracks.

Installation :
The jointmeter assembly consists of a composite
housing of PVC and Nylon, a stainless steel target AIM 807 SENSOR HOUSING WITH DISPLACEMENT
SENSOR (PUSH IN TYPE)

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Easy Installation:Simplified installation

VIBRATING WIRE TRIAXIAL procedure, anchors are grouted in the concrete
JOINT METER in the shallow drill holes.

Tri-axial joint meters can be easily connected to
Purpose : a Data logger or to a Data Acquisition System
Vibrating wire tri axial joint meter is used for for continuous unattended monitoring.
monitoring of block joint movements (opening/
closing) and construction joint movements in the Applications :
foundation and drainage galleries of dams in XYZ axis. The vibrating wire type submersible joint meter is
used to monitor movement at block joints and
Operation :
cracks and is designed to with stand extended
The submersible VW triaxial jointmeter consists of
submersion.Typical applications include:
three nos waterproof push in type displacement
sensors, along with a 3-D mounting system and
Monitoring movement at submerged
groutable anchors. The groutable anchors are costruction joints in concrete dams.
installed on opposite sides of the joint.Various
Monitoring joints or cracks in tunnels and
components of the 3-D mounting system are tanks.
secured to the anchors, and the VW push-in
displacement sensors are positioned to provide the AIM 808
required range. Signal cables from the displacement
sensors are routed to a Digital readout unit/ Data Range : ± 25 mm, ± 50 mm
logger. Accuracy : ± 0.5 % FS
A VW Digital indicator or data logger is used to read/ Oparating Temp. : – 10 to +70° C
record the data from the respective sensors. A change Coil recsistance : 140 - 160 ohm
in the distance across the joint causes a change in Material : Stainless Steel
the output signal produced by the VW displacement
Sealing : Hermetically sealed with
transducer when excited by a readout unit / Data
inert gas, meets IP - 68,
logger. The initial readings are used as a datum, and
weather protection clause
further subsequent readings are compared to the
datum to calculate the magnitude, rate, and Thermistor : Inbuilt YSI - 44005 or
acceleration of movement of the joint. equivalent, (3k Ω @ 25° C).
Cable : 4 core shielded cable, 1 m
Advantages : length

Subermisible:The system is waterproof to 10 bar
(150 psi) of water pressure.

Multi-axis Monitoring: Triaxial jointmeters can
monitor displacement in three orthogonal axis.

AIM 808 TRIAXIAL JOINT METER ASSEMBLY

AIM 808 TRIAXIAL JOINT METRE

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Installation :
VIBRATING WIRE The gauge is essentially a vibrating wire load cell
REINFORCEMENT LOAD and a normal procedure is to weld this gauge in
GAUGE series with the reinforcing steel that is to be
instrumented. The ends of the gauge are trimmed
Purpose : down to the same diameter of as the reinforcing
Vibrating wire reinforced load gauges are used for steel and are of sufficient length to allow the gauge
measurement of stresses in the reinforcement in to be welded in place without causing any damage
concrete structures, offshore structure concrete to the instrument due to the welding process. The
piles etc. reinforcement bar along with the Reinforcement
Load Gauge is embedded and the lead wires are
Operating Principle : taken out of the structure for connecting to the
The basic principle is that the change in natural Readout Unit
frequency of a stretched wire depends on the change
in tension in the wire. The gauge wire and magnet AIM 811 Vibrating Wire Reinforcement
systems used for exciting the gauge wire and Load Gauge
making the frequency measurements are mounted
Calibration : Each gauge is individually
axially in a milled slot in the gauge. Thus, the change
calibrated.
in frequency of the gauge wire is a measure of the
axial strain in the gauge. The gauge wire is sealed in Linearity : ± 1% of FS or better.
a small metal tube and the entire load cell is sealed Hysterisis : ± 1% FS or better
with ‘O’ rings and an outer thin walled cylindrical Range : 0 - 150 N/mm2
housing, so that the instrument is completely water Length : 470 mm
tight.
Cable : 4 core shielded cable, 1 m length
Frequency readings are taken with the help of
AIM 812 Vibrating Wire Reinforcement
vibrating wire readout units.
Load Gauge
Advantages Same as AIM 811, but welded with 2 pieces of 1500

Sensitive robust and reliable, with excellent long mm long, 20 mm OD reinforcement steel bars at
term stability. both ends.

Readings are unaffected by cable length.

Common readout unit for all vibrating wire
type instruments.

The load gauge is fabricated of higher strength
steel than normally used reinforcing steel so that
the gauge operates within its own elastic range,
even after the reinforcing steel has started to
yield.
AIM 811 REINFORMCEMENT LOAD GAUGE

Applications :

Monitoring the stress in the reinforcement in
concrete structures.

Measurement of stresses in bridges, offshore
structures, concrete piles etc.

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 STRUCTURAL MONITORING

Concrete and steel box girder bridges

VIBRATING WIRE STRAIN

Flyovers
GAUGE EMBEDMENT TYPE
Motorways

Concrete dams
Purpose :

Roof struts
Vibrating wire embedment type strain gauges are
used for monitoring of internal strain in concrete
Pressure vessels & Silos
by embedding in structure in single or
Cast-in-piles / driven piles
multi-directions configuration.
Tunnel linings
Operating principle :
Coal Mines
Each gauge contains a high tensile steel wire in
Concrete Caissons & reservoirs
tension between two end flanges and enclosed in
The stainless steel gauge, being robust, it is most
steel tube. A plucking coil is positioned at the centre
frequently used for strain investigations on site.
of the tube and in close proximity to the wire. A
plucking coil positioned at the centre of the tube AIM 815 Vibrating wire Strain gauge
and in close proximity to the wire. embedment type, thermister
A current fed to the coil pulses the wire which then incorportated
oscillates in an exponentially decaying half-wave Gauge Length : 125 mm
mode along its length. Range : 3,000 microstrains (± 1500
microstrains)
The coil meantime acts as a pick up device and the
voltage induced in it has the same frequency and Sensitivity : 1 microstrain
amplitude characteristics as the oscillating wire. Operating temp : – 10 to +70° C
When the gauge is embedded in concrete the strain Coil Resistance : 140 - 160 Ω
resulting from the stresses developed in the Material : Stainless Steel
concrete alters the natural frequency of oscillation
Thermistor : YSI - 44055 or equivalent,
of the wire.
(3k Ω @ 25° C)
The strain in the concrete is proportional to the Sealing : Hermetically sealed with
square of the frequency of oscillation of the wire inert gas, meets IP - 68,
and to the gauge thus provided a sensitive system
weather protection clause
for measuring internal strains.
Cable : 4 - Core, shielded, 2 m.
The signal from the coils coupled to external
measuring equipment via a flexible cable. By AIM 816 Embedment type Vibrating
careful placement of gauges during the casting Wire Strain Gauge
phase it is possible to record the complete strain Thermister incorporated.
history of the structure at one single remote reading
Same as AIM 815, but with a guage length of 55mm
console.
For measuring long term, slowly varying strains
gauges of vibrating wire type are preferable to other
forms, having an excellent long term stability.

Applications :
For measurement of internal strain in concrete by
embedding in the structure in single of multi-axis
configurations. These are extensively used in the
following structures : AIM 815 EMBEDMENT STRAIN GAUGE

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AIM 81502 No-Stress Strain Meter for 125 observations of which are made by measuring the out
mm gauge length strain gauge. put from the coil which now acts as a pickup device.
Gauges with other gauge lengths can also be
Applications :
supplied on request.
For measurement of Strains on the surface of metal
AIM 81503 No-Stress Strain Meter or concrete, these gauges can be adopted for
for 55 mm gauge length strain
mounting on different types of surfaces.
gauge.
AIM 820 Vibrating Wire Strain Gauge,
Surface Mounting type

Gauge Length : 125 mm

Range : 3,000 microstrains
(± 1500 microstrains)
Sensitivity : 1 microstrain
Operating temp : – 10° to + 70 °C
Coil Resistance : 140 - 160 Ohm
Thermister : YSI - 44055 or equivalent,
(3k Ω @ 25 °C)
Material : Stainless Steel
AIM 81502-1 5 - P ROSSETTE WITH STRAIN GAUGES Sealing : Hermetically sealed with
inert gas, meets IP - 68,
weather protection clause
SURFACE MOUNTING Cable : 4 core, shielded, 2 m.
TYPE VIBRATING WIRE Accessories : End blocks and dummy sensor.
STRAIN GAUGE
AIM 821 Vibrating Wire Strain Gauge,
Purpose : Surface Mounting Type
Vibrating wire surface mounted type strain gauges Same as AIM 820, but having
are used for monitoring strain on the surface of 55mm gauge length with end
metal/ concrete. blocks and Dummy Sensor.

Operating principle :
The Vibrating Wire Strain Gauge uses a high
tensile steel wire in tension between the two end
blocks to sense the variation in surface strain over
the gauge length. This strain variation develops a
corresponding change in tension in wire. A
plucking coil in mounted in the protective
enclosing tube surrounding the wire. A current
pulse fed to the coil, shock excites the wire, which
then oscillates at a frequency determined by wire
tension. Variations in strain are thus converted to
changes in frequency of oscillation of wire,
AIM 820 SURFACE MOUNTING STRAIN GAUGE

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Installation :
VIBRATING WIRE Tensile loads in rockbolts and cables are measured
CENTRE HOLE LOAD CELL by installing Centre Hole Load Cells between the
rock/concrete face and the tensioning nut of the
Purpose : bolt or anchor. For the most reliable results, a
Vibrating wire load cells are used for monitoring concrete bearing pad should be cast, with its upper
of load in rock bolts, tie backs , foundation face flat and perpendicular to the bolt or cable. A
anchors tunnel supports and in prestressing. bearing plate is placed beneath the cell to spread
the load and to take up any residual nonalignment.
Operating Principle : A further bearing plate is placed between the cell
The vibrating wire load cell comprises of a set of and anchor. The assembly is centralised and held
three or six vibrating wire gauges, mounted in place by applying a small tension to the bolt or
parallel to each other, equally spaced in a ring in cable. Fault in centralisation or alignment will be
an alloy steel cylinder. The method of construction apparent from differences in load readings at each
results in a very robust instrument suitable for use of the vibrating wire gauges in the cell. In situations
where high performance, longevity and where speed of installation is important, the
mechanical strength are important. bearing pad may be formed using high alumina
A heavy gauge, multicore, sheathed cable connects cement or resin grout. Readings of the vibrating
the cell to the readout unit. The mode of operation wires are averaged to obtain the bolt or cable
is by electrical plucking of the vibrating wire. tension. In multi-strand cable anchors, it is possible
to tension the strands uniformly, by monitoring
The change in load acting on the load cell is
and balancing the load reading for each of the
proportional to the difference of the squared
vibrating wire gauges.
frequency of vibration for the corresponding load.
The readings are taken on AIM 871,
AIM 875 or AIM 878 Dataloggers

Advantages :

Accurate, robust and long term stability.

Negligible temperature effects compared with
oil filled load cell.

Fast response time.

Accuracy unaffected by cable length.

Suitable for remote readings.
AIM 831 SERIES CENTRE HOLE LOAD CELLS

Capable of reading eccentric loads.
AIM 831 to AIM 840 Vibrating Wire Centre

Double sealing to avoid moisture. Hole Load Cell

Common readout for all vibrating wire type It comprises of an alloy steel cylinder with three
instruments. gauges at 120° in the cylinder walls. Each gauge is
fixed with non-slip cylindrical end clamps.
Applications :
Electromagnetic pulsing and sensing units with,
The measurement and control of load includes : over voltage surge arrestors are mounted adjacent

Load in rockbolts, tie backs, foundation anchors to each wire on the outer face of the cylinder. The
and tunnel support. entire unit is then protected by an outer zinc plated
steel sleeve with ‘O’ ring seals.

Tension in cable anchors and multistrand
tendon anchors.

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Range : 250, 500, 1000, 1500, 2000, Catalogue Working Overall* Centre Hole Height
3000, 4000, 6000 kN No. Load (kN) Dia (mm) Dia (mm) (mm)

Accurancy : ± 1 %FS AIM 831 250 102 40 80

AIM 832 500 121 50 80
Coil Resistance : 140 - 160 Ohms
AIM 833 500 152 90 80
Sealing : Hermetically sealed with AIM 834 1000 146 50 80
inert gas, meets IP - 68, AIM 835 1000 165 90 80
weather protection clause AIM 836 1500 220 150 80

Operating temp : – 10° to 70° C AIM 837 2000 275 190 80

AIM 838 3000 292 190 80
Material : Stainless Steel
AIM 839 4000 292 190 80
Thermister : YSI - 44005 or equivalent, AIM 840 6000 310 205 90
(3K Ω @ 25° C). * Overall dia does not include extension connector for cable.
Cable : 6 core shielded cable, 1 m
length

AIM 831 SERIES LOAD CELL FOR CABLE ANCHORS

AIM 831 CENTRE HOLE LOAD CELLS Centre Hole Bearing Plates : Dimensions
WITH BEARING PLATES
Catalogue To use with Overall Centre Hole Height
Centre Hole Bearing Plates : No. Load cell Dia (mm) Dia (mm) (mm)
AIM 83101 AIM 831 103 40 23
Centre Hole Bearing Plates comprising epoxy
painted steel discs with central hole for use with AIM 83201 AIM 832 113 50 33

AIM 831 to AIM 840 load cells for monitoring AIM 83301 AIM 833 143 90 33
tension in rockbolt or cable anchors. The plates AIM 83401 AIM 834 136 50 43
incorporate three location dowels to assist
AIM 83501 AIM 835 163 90 43
concentric mounting of the load cell. Details of
AIM 83601 AIM 836 218 150 48
dimensions as tabulated:
AIM 83701 AIM 837 262 190 58

AIM 83801 AIM 838 278 190 63

AIM 83901 AIM 839 292 190 68

AIM 84001 AIM 840 315 200 74

Vibrating Wire Centre Hole Load Cell :

Dimensions and Range AIM 831 Series LOAD CELL FOR ROCK BOLTS

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secured at anchor points to the body of the

INSTRUMENTED ROCKBOLT Rockbolt at predetermined positions. The
The Instrumented Rockbolt is used to measure extensometer rods extend from each anchor point
change in the magnitude of loads distributed along to the measuring head.
the length of the bolt as a function of time. Any extensional and/or compressional force
initiated by loading at locations along the length of
Applications :
the Rockbolt cause the displacement of adjacent

To measure rockbolt loads. rod extensometer anchor points. Consequently a

To monitor the behaviour of jointed roof and change in the position of a particular anchor point
floor strata during various mining tunnelling causes a movement of the attached extensometer
stages. rod which moves independently of the other
anchor points.

To determine the magnitude of loads on roof
supports. Movement of one or more of extensometer rods
in relation to the measuring head is monitored by
Description :
inserting a dial depth gauge into the appropriate
Rockbolts provide a conventional means of aperture in the measuring head.
strengthening underground openings and
stabilizing cut slopes in rock. It is therefore AIM 854 lnstrumented Rockbolt,
important to check that installed Rockbolts will 25 mm dia, 3 m long
not fail through overloading.
AIM 855 lnstrumented Rockbolt,
The lnstrumented Rockbolts comprise of a hollow
25 mm dia, 6 m long
ribbed steel bar fitted with upto four internal
extensometer rods. The extensometer rods are AIM 860 Dial Depth Gauge,
0.001 x 5 mm

AIM 854, 855 & 860 INSTRUMENTED ROCK BOLT WITH DIAL GAUGE

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AIM 89012 High Strength Test Rod, 40 mm dia.

PULL OUT TEST APPARATUS
AIM 89015 High Strength Coupling, having
This test is performed to measure the short-term RHthread to suit Test Rod on one
strength of an installed Rockbolt under field end andLH thread to suit 20mm dia
conditions. The strength is measured by a pull test Rockbolt on the other end.
in which bolt head displacement is measured as a
AIM 89016 High Strength Coupling, having
function of applied bolt load to give a load-
RH thread to suit Test Rod on one
displacement curve. This test is usually employed
end and LH thread to suit 25mm
to assess the performance of the Rockbolt anchor
dia Rockbolt on the other end.
resulting out of the quality of material used for
manufacture of Rockbolt and installation method AIM 89017 High Strength Coupling, having
used. The test equipment consists of a manually RH thread to suit Test Rod on one
operated hydraulic pump connected to hydraulic end and LH thread to suit 30mm
jack, having a high strength test rod, coupled to dia Rockbolt on the other end.
the Rockbolt under test. AIM 89018 High Strength Coupling, having
The anchor is tested by measuring the load until a RH thread to suit Test Rod on one
total displacement greater than 40 mm has been end and LH thread to suit 32mm
recorded or until the bolt yields or fractures, if this dia Rockbolt on the other end.
occurs first. The readings of displacement are taken AIM 072 Dial Gauge, 0.01 x 25 mm.
in increments of approx. 5 kN load or 5 mm
displacement whichever occus first. The rate of AIM 896 Pullout Test Apparatus
load application should be in the range 5 - 10 kN/ 250 kN (25 tonnes)
min. Readings are only taken after both load and
displacement have stabilised. The time required for
stabilisation should be recorded.

AIM 895 Pullout Test Apparatus,

capcity 500 kN (50 Tonnes)
Consists of following :

AIM 89001 Hydraulic Centre Hole Jack

500 kN (50 Tonnes) capacity with
54 mm Centre Hole, 150 mm
Ram Travel, Double Acting.
AIM 89005 Hand Operated, two Stage Pump
AIM 89007 Thermoplastic Hose, 6m long, with
pair of quick couplings.
AIM 89010 Load Gauge 150 mm dia, 500
kN x 5 kN.
AIM 89011 Reaction Frame 500 kN capacity AIM 895 PULL OUT TEST APPARATUS
with 90mm hole at base.

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AIM 89101 Hydraulic Centre Hole Jack AIM 89015-1 High Strength Coupling, having
250 kN (25 Tonnes) capacity with RH thread to suit Test Rod on one
54 mm Centre Hole, 150 mm Ram end and LH thread to suit 20mm
Travel, Double Acting. dia Rockbolt on the other end.

AIM 89005-1 Hand Operated, two Stage Pump AIM 89016-1 High Strength Coupling, having
RH thread to suit Test Rod on one
AIM 89007-1 Thermoplastic Hose, 6m long, with
end andLH thread to suit 25mm dia
pair of quick couplings.
Rockbolt on the other end.
AIM 89110 Load Gauge 150 mm dia, 250
AIM 89017-1 High Strength Coupling, having
kN x 2.5 kN. RH thread to suit Test Rod on one
AIM 89111 Reaction Frame 250 kN capacity end and LH thread to suit 30mm
with 90mm hole at base. dia Rockbolt on the other end.

AIM 89012-1 High Strength Test Rod, AIM 89018-1 High Strength Coupling, having
RH thread to suit Test Rod on one
40 mm dia. end and LH thread to suit 32mm
dia Rockbolt on the other end.

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can accurately measure the resonant frequency of

VIBRATING WIRE TYPE
the wire. A more sophisticated microprocessor
AUTOMATIC based readout unit can display the frequency as
WATER LEVEL RECORDER well as the physical parameter directly in
engineering unit.
AIM 827 Water Level sensors are suitable for connection to
data loggers for recording data automatically at
Automatic Water Level Recorder is designed for
pre-determined intervals. A single unit may be
accurate, remote monitoring of ground water level
connected to a mini logger or single channel logger.
in a reservoir / borehole, coastal and inland waters,
By the use of appropriate software, the data logger
ports, wells and rivers. It can also be used for
can present recorded data in desired formats,
recording water level in canals, open channels,
predict trend of variations and even generate
sumps and underground and overhead tanks /
alarms at pre-determined set points.
sumps.
It essentially consists of a vibrating wire pressure
sensor connected through a vented cable to a digital
read out unit, for displaying the water level in its
engineering units.

Pressure Sensor :
The model AIM - 827 Automatic Water Level
Recorder consists of a vibrating wire pressure
AIM 827, 875 WATER LEVEL RECORDER
transducer encapsulated in a stainless steel housing
of diameter 30 mm. It is factory connected to a
Standard Ranges 10, 20, 30, 50 m water head
sealed 4 core cable with air vent conduit for
compensation of variation in barometric pressure. Accuracy ± 1% FS

The vibrating wire sensor element is completely Material (outer body) Stainless Steel

isolated from the total stresses acting on the body. Operating Temperature – 10° to +70° C

It has a high or low air entry filter affixed through Coil Resistance 140 - 160 ohm
Thermistor YSI 44005 or equivalent,
an ‘’O’’ ring at one end. The other end has a sealed ( 3k Ω @ 25° C )
cable entry. With the filter in place, the main Filter High and low air entry Ceramic / Steel
diaphragm of the piezometer is isolated from solid Dimension 30 mm dia x 145 mm length
particles and senses only the fluid pressure to be Cable 4 core cable encapsulated in a PVC
measured. The filter is easily removable for tube, open to atmosphere maximum
length 20 meter
calibrations and saturation.

Principle of Operation : Specifications :

Any change in pressure causes a change in tension Each sensor is individually calibrated at known
of a pres-stressed magnetic wire sensor. To temperature and atmospheric pressure. Five point
measure the change in tension of the wire, its calibration is done for each sensor and readings
frequency of vibration, which is a function of the are provided in terms of Linear Units ‘’LU’’. Linear
tension, is measured. A conventional readout unit Unit is defined as Frequency 2/1000. This is an
internationally accepted unit and is used by all

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world class indicators. This facilitates the user in is checked under extreme conditions of
converting data to Engineering units since this is a temperature and a correction factor is provided in
linear function of the pressure as the term indicates. the Data Sheet.

Observations are taken in five or more steps of equal Since piezometer is a pressure measuring device,
pressure starting from Zero condition to Full scale any change in atmospheric pressure will have a
condition. The Gauge Factor is calculated as Range/ direct effect on the data. Variation of atmospheric
(R0-R1). Where R0 and R1 are reading at zero pressure is of the order of ± 0.03 kg/cm2. This effect
pressure and Full range in LU. Gauge factor will be distinct in sensors of low range eg.
multiplied by the difference of Zero reading and 3 kg/cm2 or 5 kg/cm2 The user is hence advised to
Current reading will give the value of current take zero readings stamped with temperature and
pressure in Engg. Units. The same gauge factor when atmospheric pressure at site before installation. By
fed into the programmable indicator along with the substituting these readings along with temperature
zero reading, provides a display directly in and pressure values in the equation given in the
engineering units. data sheet provided with each sensor, the exact
value of pressure can be calculated at any time.
Correction of temperature and atmoshperic
pressure effect : Piezometer accuracy is specified as below 1% full
scale. However better results may be obtained by
Design of piezometer reduces the thermal shift to
the use of Polynomial constants provided in the
a minimum value. However to completely
calibration sheet.
eliminate the error due to thermal shift, each sensor

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Installation :
VIBRATING WIRE
The water leakage measurement system is installed
WATER LEAKAGE in dams, embankments and tunnels to monitor
MEASUREMENT SYSTEM the water leakage. A transmitter unit can
alternatively be located near the liquid level
Purpose : indicator and is connected to the control unit by a
Vibrating wire water leakage measuring systems standard telephone line. A command unit is then
are used for measuring water leakage and flow in located at a point where remote measurements are
dam galleries by installing V Notch weir coupled to be made.
with vibrating wire sensor for remote monitoring
of water leakage. AIM 826 Vibrating Wire Water Leakage
Operating Principle : Measurement System
Leakage water from different locations is made to travel Consists of :
to a stilling tank through pipes and open channels AIM 82610 Assembly of a pair of V.W.
provided in the system. The leakage water is thus type sensors enclosed in an
collected in the tank for measurement. From the first environmental proof fibre glass box.
compartment of the tank; the leakage water passes AIM 82611 Float Cylinder : Brass float cylinder
through the baffle plate to ensure that water received 50 mm dia x 650 mm long enclosed
in the second compartment is free of turbulance. in PVC pipe, OD 110mm x 2m
The sensing element consists of a pair of partially long; one pair.
submerged cylinders each having a vibrating wire AIM 82601 ‘V’ Notch Weir Plate made of
type sensor. Each of these cylinder is suspended from Stainless Steel; capacity < 30 litres
the vibrating wire through a calibrated spring. The second. OR
difference in the weight of the cylinder at various AIM 82602 ‘V’ Notch Weir Plate made of
degrees of submergence determines the water level. Stainless Steel; capacity < 136
This variable force is measured through the change litres/sec OR
in frequency of the vibrating wire attached to the AIM 82603 ‘V’ Notch Weir Plate made of
spring and is a measure of hydraulic head on the ‘V’ Stainless Steel; capacity < 376 litre
Notch Weir and is therefore a measure of the flow seconds.
of water over the weir.
Advantages : VIBRATING WIRE TRANSDUCER

Robust, reliable, simple to operate and read.

DATA

The sensors are enclosed in fibre reinforced TRANSMISSION

plastic casing for protection against corrosion BOUYANCY READ-OUT

and mechanical damage. CYLINDER

SHUT OFF

Suitable for remote readings. VALVES
MEASURING ENTRY OF

Common portable readout unit can be used WEIR, WATER

with all vibrating wire type instruments. WAVE FILTER

PERFORATED
This instrument has built in redundancy. The
second sensor which is a reserve one, is made use DISTANCE FOR STEEL
WEIR PLATE TO
of in the event of failure of any one of the two CENTRE OF THE
V.W.sensors provided. GAUGE SHOULD BE 3
TO 4 TIMES THE
HEIGHT OF THE WEIR
Applications :

For measurement of water leakage through dams. AIM 826 AUTOMATIC WATER LEAKAGE MEASUREMENT SYSTEM

For measurement of liquid level and flow.

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AIM 89101 PVC Cable Splicing Kit

INSTALLATION ACCESSORIES
AIM 89102 Heavy Duty Splicing Kit (SS)

AIM 89011 Shield Cable, PVC, AIM 89103 Cable Sealing Compound

multi strand shielded, 2 pair (4 core) AIM 89104 Tool Kit

AIM 89012 Armoured Cable : AIM 895 Coloured Adhesive Tapes

Armoured cable (Heavy Duty) Adhesive tapes in different colours for colour
single pair (2-core). coding of cables during installation. Supplied in
set of 5 colours, 10m long
AIM 89102-2 Splicing Kit
AIM 892 Watertight Junction Box
Splicing Kit stainless steel for
AIM 89012 The 10- way junction box acts as a junction between
individual cables and with AIM 89014 & AIM
AIM 89013 Armoured jelly filled cable, 2 pair 89015 multicore cables leading to switch box.
(4-core) AIM 89301 Cable termination and switch box
AIM 89014 Armoured Cable for connecting 10 individual
instruments to Readout Unit
Armoured jelly filled cable, 3 pair
through rotary switch.
(6-core)
AIM 89301-1 Cable termination and switch box
AIM 89015 Armoured Cable for connecting 13 individual
Armoured jelly filled cable, instruments to Readout Unit
through rotary switch.
10 pair (20 core)
AIM 89302 Cable termination and switch box
AIM 89016 Armoured Cable:
for connecting 25 individual
Armoured jelly filled cable, instruments to Readout Unit
through rotary switches.
20 pair (40-core)

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Temperature : – 10° to 50°C

READ OUT UNIT
Engineering
AIM 871 Portable, Single Channel Unit Display : me (micro-strain), ksc
Readout Unit (kg/cm2), kg, t, mm, m, C
Common for all Vibrating Wire Gauges, with and deg.
liquid crystal display to show the time in seconds Temperature
for 100 cycles of vibration Sensor(Thermistor) : YSI - 44005 or equivalent,
AIM 87105 Battery for Readout Unit AIM 871 (3K Ω @ 25°C).
Sealed maintenance free, set of 2 Baud rate : 1200, 2400, (2400 default)
Hand shake : X ON and X OFF
AIM 875 Multichannel Digital Readout
Parity : None
Unit for PC Interface.
Start & Stop Bit : Single
Frequency Range : 500 to 5000 Hz
Data Bit : 8
Measuring Time : 0.01 ms
Data Transfer
Period
Format : Comma, delimited ASCII
Resolution : 0.0001 ms text file
Sensor Excitation : 5V (typical) square wave,
peak to peak
Display : 16 character x 1 line
Backlit, Alpha numeric
LCD
Calibration factor : Programmable
Real time Clock : dd:mm:yy, hh:mm:ss
Interface : RS-232 Serial Interface
Power source : 6V, 4 AH Field maintenance
free rechargeable battery
Memory Operating : 8KB (NVRAM) VIBRATING WIRE GAUGES, WITH LIQUID CRYSTAL DISPLAY

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Displays channel data, alarm status and system

DATA ACQUISITION SYSTEM information.
AIM 878 Data AcquisitionSystem
20 TTL / CMOS - compatible digital inpu
(Data Logger) hannels for digital state.
This Data Logger (Data Taker Model DT - 515 &
5-Key Keypad for display selection, scrolling,
DT - 615) provides for unattended scanning and backlit.
remote control of all types of vibrating wire
5 Change over relay digital output channels
instruments. It also reads Thermocouples, (110 VAC / DC 5 A), 5 open collector digital output
Platinum RTDs, Thermistors, Semi Conductor and channels (30 VDC, 200 m A)
Resistance Strain Gauges It is a microprocessor
Power directly from host Data Taker, sleep (low
based battery powered data logger with facility to power mode) when Data Taker sleeps.

Voltage : 9-18V AC or 11-24V DC external power.

Analog Channels :
Channel Number
Two wires : 10
Two wires with one shared terminal : 30
Sensor Excitation
DC Voltage : 5V at 100 mA switched
AIM 878 DATA LOGGERS
Multiplexer
set alarms on all channels. Has an integral display Type : Relay ± 100V input
and key pad. Common mode range : ± 100V (100V range only)
Input impedence : 1M Ω OR > 100 M Ω
Important Features : programmable

Universal Channel Support Sampling

Suitable for 10 differential or 30 single ended Maximum sampling speed : 25 Hz
channels which can be used in any combination. Effective resolution : 15 bits

Expansion by external modules of 10/30 analog Linearity : 0.01%
channels. Common mode rejection 25 mV range : > 90 dB

Maximum No. of Channels - 90 single ended. Sensor Support :
Vibrating Wire

Battery backed internal RAM, stores up to 166,
530 data points. Frequency Range : 500 to 5000 Hz
Coil Resistance : 50 to 200Ω

Removable memory card.
Stimulation method : Single pulse pluck

Compatible with spreadsheets, graphic and
Thermistor
statistical packages etc.
Type : YSI 400xx series

Compatible with most communication Resistance range : < 7 kΩ
methods including modems, radio and satellite. : > 20 kΩ with parallel resistor

All programming is by simple descriptive Sensors - Comments
commands, which are entered from a host A wide range of sensor scaling and linearizing
computer via the serial interface. facilities is provided including polynomials,

Commands can be pre-recorded into a memory expressions & functions.
card, and these are automatically executed Calculation Channels
whenever a memory card is inserted.
Any expression involving variable & functions

LCD type, 2 line x 16 characters, backlit, alpha including:
numeric display. Sin( ), Cos( ), tan ( ) asin ( ), acos ( ), atam ( ), abs

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( ), sqrt ( ), average, maximum, minimum, time of Display functions : channel data, alarm, battery
max, time of min, Variance, Integral, histogram status, data capacity
Scheduling of Data Acquisition Keypad : 5 keys for scrolling, function execution
Numbers of Schedule : 4 acquisition schedules Real Time Clock
1 immediate schedule For time stamping of data, scheduling and timers
1 Alarm schedule Normal Resolution : 1 second
Scan trigger : time base or digital event Accuracy : 2 second per day (25°C)
Conditional scanning : While digital input high Power Supply
Time base scheduling : from seconds to months in Voltage Range : 11 to 24 Vdc or 9 to 18 Vac
increments of 1 second or as fast as possible, Power Consumption
typically 25 samples per second In normal mode : 1 W
Dynamic scan time base change : yes Sleeping : 2 mW
Alarm Typical low power operation : 20 mW
Condition : high, low, within range are out side Internal Main Battery:
range Voltage Capacity : 6V (1.2 AHr)
Delay : Optional time period from alarm response Internal Backup Battery:
Action : Set digital output, executes any commands Type : 3V 1/2 AA Lithium
Data Storage
Optional Accessories
Internal
Channel Expansion Module (CEMS3)
Type : Battery backed SRAM
Multiplexer : relay
Capacity : 166, 530 data points
AIM 87801 Channel Expansion Module
PC Card
for Data Logger, capacity 30 single
Types : SRAM upto 4 MByte, Type 1
ended or 10 differential channels.
Card Voltage : 5V types
Capacity: Up to 13, 90, 000 data points
Data Format : proprietary
Download Data Format
Format : ASCII floating point, fixed point or
exponential formats
Compatibility : Spread sheets, world processors,
graphing, packages, statistical programs and
SCADA software
Serial Interface AIM 87801 CHANNEL EXPANSION MODULE CONTROL PANEL
The data logger is programmed and data extracted DATA LOGGERS

via the RS 232 serial interface Channel Number : 10 two wire 30 two wire shared
Speed : 300 to 9600 baud (9600 default) terminal
Handshake : X ON and X OFF SRAM PC Card ( MC 1024P, MC.4096P )
Wake from sleep : Yes Capacity : 1 MByte, approximately 340,000 data
Isolation : 500V points
Compatibility : Computer, modems, satellite- 4 MByte approximately 1,390,000 data points
modems, radio-modems and printer.
De Logger TM 4 Pro : Graphical programming and
System supervision software.
Display and Keypad Note : Only two AIM 87801 Channel Expansion
Model : DT 615 only modules can be connected to one AIM 878 Data
LCD, 2 lines by 16 character, backlit Logger.

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ADVANCED
TECHNOLOGY
& ENGINEERING
SERVICES

CONSULTANCY SERVICES
• Geotechnical Investigations, Slope Stabilisation & Ground Improvement
• Condition Survey • Non Destructive Testing & Rehabilitation of Structures
• Numerical Modelling • Structural Instrumentation • Concrete Technology
• In-Situ Testing Obtaining design parameters • Laboratory Testing of
Rocks / Soils / Concrete & Its Ingredients / Other Materials
(In Fully Equipped In - House Laboratory) • Dams & Dam Safety
• Water Resources Development Projects • Structural Designs

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Instrumentation. Slopes are stabilised using the

ABOUT ADVANCED technique of SOIL NAILING, which is one of the
TECHNOLOGY & most economical & durable methods.
ENGINEERING SERVICES Geotechnical Investigations :
Field Investigations
Advanced Technology and Engineering Services
Slope Stabilisation
(ATES) is the Consultancy Division of AIMIL Ltd.
in New Delhi. AIMIL is an ISO-9002 Company and – Drainage
is well known in India and abroad since 1932 for – Soil Nailing
manufacturing and sales of civil engineering and – Use of Geogrids
scientific instruments. ATES comprises of a team Ground Improvement :
of highly qualified professionals, practicing in the
Some of the projects completed by us are :
area of Civil and Mining Engineering.
Vizag Port Connectivity Road Project, Vizag
Services Provided By ATES : Kali Gandaki Project, Nepal
ATES provides services in the following areas: Tungabhadra Dam, Karnataka
1. Geotechnical Investigations, Slope Stabilisation Middle Marysangdi H.E. Project, Nepal
& Ground Improvement
Malana H.E. Project, H.P
2. Condition Survey, Non Destructive Testing &
Tehri Hydro Project, Uttaranchal
Rehabilitation of Structures
Sewa H.E. Project, State II, H.P
3. Numerical Modelling
Nimoo Bazgo H.E. Project, J & K
4. Field Instrumentation
Middle Siang H.E. Project, Arunachal Pradesh
5. Concrete Technology
Chutak H.E. Project, Kargil, J & K
6. In-Situ Rock Mechanics and Soil Testing
Chamera H.E Project, Stage III, H.P
7. Laboratory Testing of Rocks / Soils / Concrete
Allain Duhangan H.E. Project, H.P
& its Ingredients / Other Materials (In fully
equipped in - house laboratory) Parbati H.E. Project, Stage III, H.P

8. Dams & Dam Safety NTPC Projects at Ballabhgarh (Haryana),

Vishakapatnam (A.P), Anta (Rajasthan), Rihand
9. Water Resources Development Projects
(U.P), Talcher (Orissa), Ramagundam (A.P)
10. Structural Designs
Slope on Hardwar Badrinath Road near Rishikesh,
ATES Associates : Uttaranchal
– ITASCA Consulting Group Inc., USA Ambaji Ropeway,Gujarat
– Anasys-Civil FEM, Spain Mansadevi Temple, Uttaranchal
– Malcolm Dunstan & Associates, U.K. Chandidevi Temple, Uttaranchal
– Central Mining Research Institute, Dhanbad Numerical Modelling :
Geotechnical Investigations, Slope In the recent past numerical modelling has emerged
Stabilization and Ground Improvement : as powerful technique for effective analysis and
economic design in Civil Engineering practices.
ATES has a strong analytical and design capability.
ATES offers consultancy services, especially in
The data required for the analysis is obtained by
‘Numerical Modelling’ to provide the necessary
ATES personnel themselves. The performance of
support to design engineers of the Central and State
structures is predicted on the basis of Numerical
Government agencies and consulting companies
Modelling which is verified by Field
who may require advanced numerical analysis for:

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– Underground Excavations of concrete Dam and 3D analysis of maximum

Case study of Tehri Hydropower Project principle stress - NOF portion).
(Underground Machine and Transformer halls), – Slope Stability
where the Numerical Modelling coupled with – Barrages
instrumentation was the basis for design of the Areas of Specialization :
excavations is on the page no. 89 - 90. This paper
• Static and Dynamic analysis
which was presented during International
Congress on Rock Mechanics, Paris in 1999 and • 2D and 3D modelling
describes the Methodology on the design of large • Non-linear analysis of continuum soil or rock
U/G Caverns in Himalayan Region. • Discontinuum modelling of jointed media

– Dams • Seepage and Thermal Analysis

We have carried out numerical modelling for all Softwares Used :

types of Dam structures. The stress analysis is performed with state-of-the-
art softwares UDEC, 3DEC, FLAC, FLAC3D,
Omkareshwar Hydropower Project - Concrete
PFC2D, PFC3D etc.
Dam (3D Analysis of Maximum Principle Stress
Distribution in the body of the Dam).
Baglihar Hydropower Project - Concrete
Gravity Dam (3D Analysis of vertical displacement

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Field Instrumentation : Areas of Service :

The importance of Field Instrumentation during Monitoring of ground movement
the design, the pre- and post-construction stages Deformation - Multiple borehole
of any project cannot be overemphasized. ATES extensometer
offers a variety of field instrumentation services for
- Mechanical and remote
the performance monitoring of structures.
monitoring
Projects Executed :
Convergence - Tape Extensometer
• Omkareshwar HEP - Instrumentation &
Induced stress - Stress meter
Monitoring of Conctrete Dam.
Support pressure - Load cell, Pressure cell
• Teesta (Stage V). HEP - Instrumentation &
Monitoring of U/G Desilting Basins in Sikkim. Inclination - Inclinometer

• Sewa (Stage II) HEP - Instrumentation & Porewater pressure - Piezometer

Monitoring of U/G Surge Shaft in J & K. Subsidence - Surveying Instruments
• Parbati (Stage II) HEP - Instrumentation & Settlement - Cross arm settlement
Monitoring of Head Race Tunnel (HRT) in H.P. system
• Telugu Ganga Project Instrumentation & Monitoring of Dam
Monitoring of Earthen Dam in A.P. Concrete Dam
• Hydrostatic pressure - Piezometers
• Pressure (stress) - Glotzl cell, Flat Jack,
Vibrating Wire Stress
Meter
• Seepage - Weirs / Flumes
• Internal movements - Borehole
Extensometers, Joint
meters, Plumb lines,
Inclinometers, Tilt
Meters
• Surface movements - Theodolite EDM
• Vibration monitoring - Seismograph
3D ANALYSIS SHOWING MAXIMUM PRINCIPAL STRESS OF
BAGLIHAR CONCTRETE DAM
Earth Dam
Services are provided in : • Hydrostatic pressure - Piezometers
• Planning • Seepage - Weirs / Flumes
• Installation • Internal movements - Borehole
• Monitoring - Data Acquisition Extensometers, Joint
• Analysis of Data - Data Processing and Review Meters, Plumb Lines,
Inclinometers, Tilt
• Back Analysis
Meters
• Surface movements - Theodolite EDM
• Vibration monitoring - Seismograph

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advanced numerical modelling technique in the

DESIGN OF UNDERGROUND analysis and design of the caverns.
CAVERNS FOR TEHRI
2. POWER HOUSE COMPLEX
HYDROPOWER PROJECT,
The powerhouse complex consists of two main
INDIA BY NUMERICAL parallel caverns namely the Machine Hall (MH) and
MODELLING the Transformer Hall (TH) located about 370m
below the surface. The MH cavern is 188m long,
B. DASGUPTA, Advanced Technology and 22m wide and 47m high. There are four turbine
Engineering Services, New Delhi, India pits 16m deep on the floor of the machine hall.
M.K.V. SHARMA, AGM (D), Tehri Hydro Power The TH cavern is 161m long. 18.5m wide and 36m
Corporation, Rishikesh, India high located upstream of the MH with a 41.75m
M. VERMAN & V.M. SHARMA, Advanced rock pillar between them. In addition there are
Technology and Engineering Services, New Delhi,
India
ABSTRACT :
This paper describes the methodology of the design
of large underground caverns in the Himalayan
region of India. The design process involved
continuous evaluation of rock parameters, detailed
2D and 3D numerical modelling and monitoring
program. Hoek and Brown (1997) failure criterion
was used to estimate the rock mass strength
parameters for the model analysis and the model
results validated with the field measurements.
FIG. 1 3DEC MODEL OF EXCAVATIONS AND
1. INTRODUCTION : GEOLOGICAL FEATURES
The Tehri Hydro Power Project is under
construction at Tehri, U.P, India by Tehri Hydro other excavations such as pressure tunnels, draft
Power Corporation (THDC). The first stage of the tube, bus duct tunnels and adits joining the main
project, planned to generate 1000 MW, includes a caverns and drainage galleries.
260m high earth and rockfill dam across the river The Tehri hydropower project is located in the
Bhagirathi downstream of the Tehri town and Lesser Himalayas. The rock formation in the power
underground powerhouse complex on the left house area is mainly massive to thinly bedded
abutment hill of the dam. Phyllitic Quartzite with caverns oriented
perpendicular to foliation strike direction. There
Numerical modelling coupled with
are four major joint sets and several shear planes
instrumentation was the basis for design of the
with varying thickness (Navani, 1996). There is a
excavations. Combination of two and three-
shear zone of about 2-5m thick, dipping along the
dimensional modelling was used for effective and
foliation intersecting the caverns. The 3D model
optimized support design. FLAC (Itasca, 1995a)
of excavation and geological features are shown in
was used for 2D analysis for design of pattern
Fig. 1.
support system. Shear zones and major shear
planes were modeled in 3D discontinuum analysis 2. MODEL ANALYSIS
with 3DEC (Itasca, 1995b). Instrumentation The input parameters for the model were estimated
scheme was planned and implemented to calibrate based on the methodology proposed by Hoek and
the model. This paper demonstrates the role of Brown (1997). With the progress of excavation,

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rock mass properties were updated and support The power house complex was analyzed in 3D with
design was modified. The final rock mass busduct, draft tube and pressure tunnels joining
properties given in Table 1based on Geological the MH and TH caverns. The geologic features
mainly the folded shear zone, and about 19 shear
Strength Index = 56 (obtained from visual
planes were explicitly modelled as shown in Fig.
inspection and geological mapping), and
Unconfined Compressive Strength = 60 MPa and
mi (Hoek-Brown parameter)=10 (determined from
laboratory triaxial tests).

Table 1 : Rock mass parameters

E C φ σ1 E V C
Rock mass 8.66 GPa 2.75 MPa 33° 0.22 MPa

Shear Zone 4.0 GPa 1.5 MPa 30° 0.10 MPa FIG. 2 FAILURE REGION & ROCK BOLTS WITH AXIAL FORCES
Shear Plane 1.0 MPa 28°
1. Discontinuum analysis was performed to
The in-situ stresses were measured at the crown understand the interaction of multiple excavations
by hydrofracturing test. It was established that with geological features and identify the regions
horizontal stress ratio to vertical along the caverns requiring enhanced support.
is 0.526 and across the cavern is 0.314, while the 3. MODEL CALIBRATION
vertical stress is equivalent to overburden rock Instrumentation was planned and installed at
mass. appropriate location and time during excavation
so that maximum information could be obtained
The power house complex with MH and TH was for the calibration of the model. Rock deformation
analyzed in 2D to establish pattern support design. was measured by mechanical type MPBX. The
In this analysis the construction sequence of extensometers were installed on the roof of both
excavation and support installation was modeled the caverns from inside i.e. after the excavation of
considering the rock mass to be continuum with the crown advanced to the desired location,
Mohr-Coulomb non-linear material model. The however, monitoring usually becomes difficult
with benching.
effect of rock bolt was considered in the support
interaction analysis neglecting the shotcrete. The
length and spacing of the rock bolts were optimized
by a series of analysis, which also involved updating
of rock mass properties during construction. The
results from the model analysis show that the
failure zone on the roof is about 3m for both MH
and TH, and on the walls extended to about 12-13
m for MH and 9-11 m for TH at the mid height.
FIGURE 3 : LAYOUT OF INSTRUMENTATION
The displacement on the roof and mid height of
MH is about 2.5 cm and 2.25 cm and that of TH it
is 0.9 cm and 1.5 cm. The final support design
consists of pre-tensioned rock bolts: on the roof 25
mm dia, 6 and 10m long for MH and 6 and 8m
long for the TH, on walls 32 mm dia. varied length
of 9 to 15m for MH and 8 to 13m for TH. The axial
forces developed in the bolts were within the bolt
capacity. The excavation sequence, deformed
Distance from Transformer Hall cavern wall, m
boundary, failure region, and rock bolts with axial
forces are shown in Fig. 2. FIGURE 4 : CALCULATED & MEASURED DATA - MPBX 3

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4 CONCLUSION
The design and stability analysis of various
underground excavation in the Power House area
of Tehri Hydro Project involved detailed numerical
modelling because of intricate geometrical shapes
created by large parallel caverns and intersecting
tunnels, and complex geological features. The
Distance from Machine Hall cavern wall, m design process used for arriving at optimized
FIGURE 5 : CALCULATED & MEASURED DATA - MPBX 5 support system involved continuous updating of
rock mass parameters with excavation, 2D support
interaction analysis, 3D discontinuum modelling
The MPBX on the walls were installed and
and calibration of model results with field
monitored from the drainage galleries before the
instrumentation.
excavations reached instrumented levels. The wall
was monitored uninterrupted by the construction 5 REFERENCES
activity. A layout of the instrumented cavern is Hoek, E and Brown, E.T., 1997, Practical estimates
shown in Fig. 3. Caverns were instrumented at of rock mass strength, Int. J. Rock Mech. & Min.
three sections. Sci. & Geomech. Abstracts, 34(8): 1165-1186.
The wall instruments were installed in a phased Itasca Consulting Group, 1995a, FLAC, Fast
manner when excavation level of MH was at El Lagrangian Analysis of Continuua, Version 3.3,
609 and TH at EL 618 and the exact sequence of Minneapolis., Minnesota, USA.
excavation and installation of the MPBX was Itasca Consulting Group, 1995b, 3DEC
modeled using FLAC. The comparison of the 3-Dimensional Distinct Element Code, Version 1.5,
calculated and measured deformaton from the Minneapolis., Minnesota, USA.
caverns wall into the rock mass for MPBX 3 and Nawani, P.C., 1996, Engineering Geological
MPBX 5 is shown in Figs. 4 and 5. It can be seen modelling of rock mass at Tehri Dam site. Proc.
that the results are in close agreement indicating ISEG Symp. Modern Practices in Geotechnique,
proper validation of estimated of rock mass Lucknow, India, J. Engg. Geol. Vol. XXV,
parameter and support design. 1-4 : 150-160.

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