KHWOPA COLLEGE OF ENGINEERING

LIBALI-8, BHAKTAPUR

REPORT ON:
GEOLOGICAL FIELD WORK AT MALEKHU AND
SURROUNDING AREA

SUBMITTED BY: SUBMITTED TO:

1)Swagat Lageju (KCE077BCE086) DEPARTMENT OF CIVIL
2)Swornim Aaganja (KCE077BCE087) ENGINEERING
3)Symon Pokharel (KCE077BCE088)
4)Trilen Shakya (KCE077BCE089)
5)Unique Sakhakarmi (KCE077BCE090)

DATE:2079/11/19
 TABLE OF CONTENT

S.NO TITLES PAGE NO.

1. Acknowledgement 1

2. Introduction
2
3. Methodology
2

4. Location and Accessibility

2
5. Objectives
3

6. Chapter 1
4
7. Chapter 2
12
8. Chapter 3
18
9. Chapter 4
20
10. Chapter 5
24
11. Chapter 6
30
12. Conclusion
35
13. Reference 35
 ACKNOWLEDGEMENT
The geological field knowledge and field visit is very important especially for a Civil Engineer.
At every step, a Civil Engineer has to encounter earth, as a material or as a construction site.
The main work of a civil engineer is to study the feasibility of the construction and stability of
structures in different types of land feature including rock, their slope, riverside and clayey
portions. As the geology deals with Lithology along with the origin including types of soil,
strike, dip-direction and other geological discontinuities such as faults, folds, joints,
landslides, use of topography map for proper selection of site for the construction of a civil
structure, such as Road, Canal, Dam, Tunnel, Reservoir, etc. So, it provides the importance of
geology to Civil Engineering Professions. He or She must go through the inner core of
Engineering Geology for his/her perfections and for professionalism. Therefore, a thorough
knowledge of actual field counts for its credit.
The field visit was really fruitful to us and we certainly came to know much more about the
Site selection and the above-mentioned features.
For the basic knowledge of field work of structural Geology, the two days from 22nd of Magh
to 23th of Magh, we were taken to Malekhu and its surrounding areas for Geological excursion.
This performance was very effective for the partial fulfillment of knowledge and experience.
However, the two days of tour was not sufficient to fulfill the thirst of us. We are very grateful
to our Geology teacher Nirmal Kafle sir and Subeg Man Bijukchne sir who helped us during
the field trip and taught many important things within the limited time period.
At last, we would like to express our gratitude to our college, Khwopa College of Engineering
for providing us Bus facility.
Of course, on the course of our stay, hotel Peace Heaven and its owner who helped us
in every way to make our stay comfortable. All others directly or indirectly helping us to make
our field visit successful are thanked.

1
 INTRODUCTION
The geological field visit to Malekhu was organized by the Department of Civil Engineering
under Khwopa College of Engineering. The time duration between being two days were spent
in geological field study in Malekhu and its surrounding areas, 75Km west from Kathmandu.
On first day, we visited adit tunnel built for the investigation of Dam for Budi Gandaki
Hydropower project and visited the different structures built to control mass movement in
Krishna bhir. And on second day, we studied how to classify rock according to RMR (Rock
Mass Rating) system and prepared the geological map for road alignment.
Engineering geology is defined as the branch of geology which deals with the application of
geological knowledge in the field of civil engineering for the construction of infrastructure
such as roads, bridges, dam, tunnel etc. Engineering geology is defined in the statues of IAEG
as the science devoted to investigation, study and solution of different types of engineering
and environmental problem which arises as the result of interaction between the geology and
the work or activities of man, as well as the prediction and development of measures for
prevention remediation of geological hazards.

METHODOLOGY
The common methods used in the geological visit were the site selection and the field
observations. Different places suitable for the geological study was selected and their location
was determined by the map and the observation related to such structures were taken and
copied such as physical appearances, orientation and geological structures. Here in our
second geological visit, we observed the site for the construction of different civil structures.
Here only methodology used was the knowledge of engineering geological investigation of
such civil structures and explanation of teachers in the field. With our basic knowledge we
came to know why those structures were constructed or are going to be constructed.

LOCATION AND ACCESSIBILITY OF STUDY AREA

Budhi Gandaki Hydropower Project is a storage type project located in Central/ Western
Development region on the Budhi Gandaki River of Nepal. The project lies in Gorkha and
Dhading districts in Western/ Central Development region of Nepal. The project site is
accessible through Benighat (At about a distance of 80 km from Kathmandu) on Prithvi
Highway (Kathmandu - Pokhara). From Benighat, a motorable composite bridge can be used
to cross the Trishuli River and access the Dam site which is at a distance of about 1.5 km from
the road head. And the Krishna Bhir is a cliff located in Dhading district by the side of Prithivi
Highway, approximately 83 km from Kathmandu Valley. It was one of the most landslide
prone part of the highway. Also, we visited malekhu river which is located at about 1km from
our stay hotel. Since malekhu river was near from our stay area we went there on feet
whereas, we went to Krishna Bhir and Dam area on bus.

2
 OBJECTIVES
The main objective of the geological field trip was to learn the basic geotechnical skills in civil
engineering regarding site investigation for any civil structure, to classify rock according RMR
system and to prepare geological map. The study aimed at learning general tactics regarding
different structures of civil engineering project and observations of attitude of side slope for
construction of road along it. The main objectives of our field visit were:

 Study of Site selection of Dam,

 Study of Tunnel,
 Study of mass movement and its control measure,
 Study of rock failure mechanism,
 Study of rock mass classification system based on RMR system,
 Preparation of engineering geological map.

3
 CHAPTER 1: STUDY OF SITE SELECTION OF DAM
Location 1
This location lies on the way from Benighat (At about a distance of 80 km from Kathmandu)
on Prithvi Highway (Kathmandu - Pokhara) to Aarughat which is at a distance of about 1.5 km
from the road head.

Definition
A dam is a structure which prevents the flow of water and accumulates it in a reservoir.

eg: Karakaya Dam/Diyarbakır, Atatürk Dam/Şanlıurfa

Needs for Dam Construction

1. Drinking and domestic water supply

2. Flood control

3. Irrigation

4. Industrial water supply

5. Hydroelectric energy production

6. Retention and control of sediment

fig: purposed dam of BudhiGandaki Hydro-Electricity Project

4
Dam types

According to the size of the Dam

1. Large (Big) dam

2. Small dam

• International Commission on Large Dams, (ICOLD) assumes a dam as big when its height is bigger
than 15m.

• If the height of the dam is between 10m and 15m and matches the following criteria, then ICOLD
accepts the dam as big:

• If the crest length is bigger than 500m

• If the reservoir capacity is larger than 1 million m3

• If the flood discharge is more than 2000 m3

• If there are some difficulties in the construction of foundation

According to height of Dam

• High Dam or Large Dam

• If the height of the dam is bigger than 100m

• Medium Dam

• If the height of the dam is between 50m and 100m

• Low Dam or Small Dam

• If the height of the dam is lower than 50m

According to the static design of Dam body

• Gravity Dams (Sarıyar, Çubuk I, Kemer, Sır II,Karacaören II)

• Arch Dams (Gökçekaya, Karakaya,Oymapınar, Gezende)

• Butress Dams (Elmalı II)

• Embankment Dams (Atatürk, Seyhan, Aslantaş)

• Composite Dams (Keban)

• Gravity Dams

• Concrete Dams

5
Gravity Dams
• Use their triangular shape and the sheer weight of their rock and concrete structure to hold back
the

water in the reservoir.

• The axes may be slightly curved in the correct shape or upstream.

• The cross section of the dam is triangular-like.

• Gravity dams are required to have a solid foundation.

• The slopes of the valley can have little inclination, wide V shape.

Buttress Dams
Buttress Dams use multiple reinforced columns to support a dam that has a relatively thin structure.
Because of this, these dams often use half as much concrete as gravity dams

• The upstream side of such dams is a flat or slightly inclined reinforced concrete curtain which stands
against water pressure.

• On the downstream side there are separators that convey water pressure.

• Consealed weight dams are less concrete than gravity dams, and the foundation ditch is less. Power
stations and some other constructions may be located between the piers.

• There is too much burden on the buttress, however; not too much burden among the pylons. Zones
of weakness (faults, cracks, etc.) are encountered between the buttresses.

• Buttresscan be built in wide V-shaped valleys with little slope.

Arch Dam
Arch Dams utilize the strength of an arch to displace the load of water behind it onto the rock walls

that it is built into.

Karakaya Dam – Fırat River;

Height= 173 m

Reservoir Capacity= 9,5 billion m3

Arch Dam is a water retention facility consisting of a single curved concrete wall. To give the water
pressure to the slopes by the effect of the arch, the concrete wall is curved towards the fount. If the
pressure is equally distributed and the slopes are equally distributed, the dam can be made as a gravity
or gravity-arch. If a part of the burden can be transferred to the slopes by the influence of the arch,
this dam is called a thin arch dam. For this, the slopes should be very strong and the arch should be
well clamped into the slope. Giving the form of rock to the rocks prevents the accumulation of stresses
and the formation of cracks in the concrete. In order to clamp the arch to the slopes well, it must be

6
at least 45 degrees at the junction of the arch and the vane. Also, a large center angle should be given
to the arch as it comes from the hand.

Earth Fill Dams

Soil dams are water-holding plants made by mixing soil and rock at a specific location.

Such dams are preferred if the floor is not sufficiently strong and homogeneous.

Wide and flat earthen dam in the valley is made.

Classification of soil dams according to material used in dam body:

• Homogeneous body

• Regional

• Rock fill body

• Soil fill body

• Rock-soil body

Embankment Dam
(Rock Fill or Earth Fill Dams)

• They are mostly composed of natural materials such as, clay, sand, gravel etc...

• Impervious core is placed in the middle of the embankment body

• Generally, riprap is used to control erosion

Atatürk Dam – Fırat River;

Height= 169 m;

Reservoir Capacity= 48,7 billion m3

Composite Dams
• Composite dams are combinations of one or more dam types. Most often a large section of a dam
will be either an embankment or gravity dam, with the section responsible for power generation being
a buttress or arch.

Keban Dam – Fırat River;

Height= 163 m;

Reservoir Capacity= 31 billion m3

Gravity & Rock Fill

7
FACTORS AFFECTING SELECTION OF DAM TYPE
1. Topographical situation of the dam site: The topography of the dam site is the first criterion to be
taken into consideration in the selection of the dam type.

2. Foundation and geological structure: The foundation condition of the dam site is not suitable for
each dam type.

3. Location and type of suitable material to be used in dam construction: There are three types of
natural materials required for dam construction. These are aggregate for rock, concrete for soil, filler
and riprap for filling.

4. Transportation facilities: If the dam site is close to existing roads, which reduces the cost of new
road construction. Access to the material quarries is also important when selecting the dam site.

5. Translate (derivation) conditions: In order to be able to construct the dam under dry conditions,
the upstream and downstream sides of the construction site should be suitable to be closed with low
dams called altitude.

6. Full spillway capacity and location

7. Earthquake

8. Climatic conditions and duration of construction

9. Landslide: Large waves can be created from ground slopes of the dam to the landslide and the lake.

10. Economic situation of the country

11. Machine park area availability, types and capacities of machines

Geological Site Investigation of Dam

A. Topography
Topography dictates the first choice of the type of dam.

1. A narrow U-shaped valley, i.e. a narrow stream flowing between high rocky walls,
would suggest a concrete overflow dam.
2. A low plain country, would suggest an earth fill dam with separate spillways.
3. A narrow V-shaped valley indicates the choice of an Arch dam

B. Geological Structures
1. Bedding/Attitude
Steep dip of bed is favourable for foundation of dam. However, bed dipping downstream is
unfavourable.

8
2. Fold
When dams are placed on folded rocks, it is advantageous to place them exactly or slightly
on the upstream side of the axis of the crest of anticlinal fold (Fig. 18.11). But in the case of
synclinal fold it is better to place the dam a little on the downstream side of the axis of the
fold.

3. Position of Water Table:

It is natural that when natural equilibrium conditions are changed as due to the accumulation

of a large body of impounded water, the effects of seepage, deviation or disturbance of the

ground water flow must be considered. Some water of the reservoir will sink into the ground

9
and the movement of such water depends on the position of the water table and the nature

of the rocks.

4. Faults and Landslides:

Faults may pose a serious problem if open to the passage of water. They become potential

outlets for the escape of stored water from the reservoir. They can be treated by grouting or

alternatively by trenching along the line of fracture and filling the trench with clay puddle or

concrete.

C. Geological and Foundation Conditions

Geological and Foundation conditions should be thoroughly surveyed because the

foundations have to carry the weight of the dam. Various kind of foundations generally
encountered are

1. Solid rock foundations such as granite have strong bearing power and almost every
kind of dam can be built on such foundations.
2. Gravel foundations are suitable for earthen and rock fill dams.
3. Silt and fine sand foundations suggest construction of earth dams or very low gravity
dams.
4. Clay foundations are likely to cause enormous settlement of the dam. Constructions
of gravity dams or rock fill dams are not suitable on such foundations. Earthen dams
after special treatments can be built.

Other considerations
Availability of materials
Availability of materials is another important factor in selecting the type of dam. In order to
achieve economy in dam construction, the materials required must be available locally or
at short distances from the construction site.

10
Spillway Size and Location
spillway disposes the surplus river discharge. The capacity of the spillway will depend on
the magnitude of the floods to be by-passed. The spillway is therefore much more
important on rivers and streams with large flood potential.

Height of Dam
Earthen dams are usually not provided for heights more than 30 m or so. For greater
heights, gravity dams are generally preferred.
Hint: The availability of spillway site is very important in selection of a particular type
of dam

Silting up of Reservoir:

When the reservoir is complete, streams flowing into the reservoir will deposit their sediment

there. When the amount of such silt sediments is considerable it may lead to the silting up of

the artificial lake in a few years. The time taken for such silting will depend on the type of the

catchment area. If there is a good cover of trees it helps in reducing silting. If silting progresses

the water storage capacity is reduced impairing the efficiency of the reservoir. In such

circumstances there must be some provision for washing out the silt through some passages

in the dam or by any alternative way.

11
 CHAPTER 2: STUDY OF TUNNEL

Location 1
The location lies at Ghyalchok VDC about 3km from the Trishuli bridge upstream of
the Budigandaki river from Benighat to Aarughat way at about 100m height from the right
bank of Budhigandaki river.

TUNNEL
Tunnel is a nearly horizontal or horizontal underground passage which is open at both ends.
Tunnel is done in rock and soil mass. All tunnels in rock are driven through the rock generally
following the normal method of blasting by detonating the charges through drill holes. The
term sub-ground tunneling is used when the media of tunneling is unconsolidated deposit on
soil mass. The material excavated are huge material termed as muck and tunneling is
generally done by cutting and providing immediate support.

Types of TUNNELS
Tunnels are of different types according to their uses like:
• Traffic tunnel,
• Hydropower headrace tunnel and
• Public utility tunnels etc.

Basic Terminology of TUNNEL and TUNNELLING

1. Portal: mouth/opening of the tunnel
2) Roof/Crown: top of tunnel
3) Floor/invert: bottom of the tunnel
4) Face: Surface exposed by excavation at the end of tunnel
5) Shaft: A vertical excavation to gain access from the surface to tunnel
6) Over break: Rock excavated beyond the required Cross-section of tunnel
7) Support: structure erected in the tunnel bore after blasting
8) Lining: Casings or sand and cement spray applied to the roof and sides to give support as
well as smooth surface. It can also be of steel.

12
Tunneling Processes:
It includes excavation by conventional drilling method and new and advance TBM
method.

1. Manual (drilling, charging and blasting):

The tunneling done in this site is manual which includes face mapping, drilling, charging,
blasting, scaling, mucking, support and ventilation. Since the tunnel is of test purpose lining
is excluded. These steps of manual tunneling are explained below in tunnel digging process.
Deeper tunnels are often excavated with the assistance of a tunneling shield, a box-like
structure with small shutters opened to dig through. Once the dirt in front of the shield is
removed, the shield is moved forward to continue digging. Long roadway tunnels, such as the
Eisenhower Tunnel in Colorado, may be lit with overhead lights for the convenience of drivers
and passengers. Other roadway tunnels, such as those in Zion National Park in Utah, may
feature scenic cutouts to allow natural light to enter the tunnel in places and provide
passengers glimpses of the surrounding scenery.

Fig: Adit tunnel in Budigandaki project

13
2. Machine (tunnel boring machine TBM):
A TBM is also known as mole, is a machine used to excavate the tunnel through variety
of soil or rock strata. They may also be used for micro tunneling. TBMs have the advantages
of limiting the disturbance to the surrounding ground and producing a smooth tunnel wall.
This significantly reduces the cost of lining the tunnel, and makes them suitable to use in
heavily urbanized areas. The major disadvantage is the upfront cost. TBMs are expensive to
construct, and can be difficult to transport. However, as modern tunnels become longer, the
cost of tunnel boring machines versus drill and blast is actually less. This is because tunneling
with TBMs is much more efficient and results in shortened completion times (when they
operate successfully). There are hard rock TBM for tunneling in hard rocks and soft ground
TBM for tunneling in soft grounds. For long tunnels, multiple access shafts are drilled. When
the tunnel is finished, the access shafts may become ventilation shafts and/or emergency
exits. If they are not so employed, they are left in place for the life of the tunnel.

Fig: Tunnel Boring Machine (TBM)

14
TUNNEL DIGING PROCESS

a) Geological mapping (face mapping):

Geological mapping is also known as face mapping. Any project works begins with geological
mapping except of small-scale works.

(1) Type of rock:

In a suggested area rock type along with their properties are gathered and
studied i.e. either the rock is of required strength, durability and so on. Around
the proposed area the rock types are indicated and mapped.
(2) Site investigation:
Throughout the site investigation regarding the suitability of the project is
done. It also plans for the solution to the problems which might occur during
the construction phases and make the project economical as far as possible.
(3) Orientation:
With the orientation of the rock strata i.e. the attitude of rock the geological
map is completed. In face mapping other things can also be included such as
geological structures e.g. Fold, faults, joints, discontinuity, etc.

b) Drilling:

The area in which tunnel is to be made is drilled in order to insert the explosives and
blasted for creating the tunnel. Few drill holes are made for hard rocks but more holes are
drilled for soft rocks.

c) Charging:

Process of inserting the explosives in the drilled holes

d) Blasting:

After charging the explosives are blasted and tunnel is prepared.

e) Mucking:

The pieces of rocks obtained from blasting are called muck. The process of removal of
muck out of tunnel is mucking. Scaling is done to remove the pieces which are not removed
during blasting with the help of metal rod.

a) Support:

Different types of support system are provided in tunnel according to the rock
condition and geological structure.

b) Ventilation: It is provided in the tunnel for removal of poisonous gases out of the
tunnel as well as passing in oxygen.

c) Lining: It is the finishing process of tunneling. Smooth surface is created in the

sides and wall of the tunnel by plastering or any other method.

15
 Geological consideration for Tunnel
I)Lithology

The information regarding the mineralogical composition, texture and structure is of

great importance in tunneling. Hard and crystalline rock are always favorable. Most of the
igneous rock and sedimentary rocks like sandstone, dolomite and limestone and
metamorphic rocks like marble quartzite and gneiss fall under favorable one.

II) Geological structure

The design, stability and cost of tunnel depends not only on rock type but also the
geological structure. Following main structure features of rock have to be fully determined
along the proposed tunnel alignment:

a) Dip and Strike (Attitude)

This feature influences the design of excavation to a great extent. Presence of

horizontal strata, inclined strata etc. increases the risk of instability of the tunnel.

b) Fold

This feature signifies bends and curvatures and a lot of strain energy is stored energy
in rock. Fold increases the variation and uncertainty, area of high pressure and act as aquifer
which unexpectedly could create an uncontrollable situation.

c) Fault

As fault are the surfaces present in the rocks from where rock movement has occurred
in the past and can create problem in tunneling.IT clearly signifies the intersection of fault
plane, fault zones and shear zones with the tunnel axis is consider most vulnerable during
tunneling. Fault zones are also highly permeable zones which can create a serious seepage
problem.

d) Joint

Joints are the cracks or factures developed in all type of rock due to variety of causes.
Although the type of joints and its extension decreases with the depth the presence and
orientation of joint has to be investigated properly.

III) Ground water condition

Determination of ground water condition in the region of tunnel project is not to be

underestimated at any cost. This factor influences the tunnel rock in two ways:

a) Through its physio-chemical action.

b) Through the release of pressure in the direction of excavation affecting the rock strength
parameter.

16
Three possibilities of relationship between tunnel axis and ground water level can be in
existence.

a. The tunnel axis may be passing through impervious formation (safe)

b. Tunnel axis above the ground water table (safe)

c. Tunnel axis below the water table (highly unsafe/ problematic)

TYPES OF TUNNEL SUPPORT

1. Steel rib
2. Steel rib with precast concrete
3. wire mesh
4. Shotcrete
5. Rock bolt
6. Grouting
7. Reinforcement

17
 CHAPTER 3: STUDY OF ROCK FAILIURE MECHANISM

Location 2
This location was about 2km from our stay area along the Prithivi highway.

Rock failure mechanism:

There are three types of rock failure mechanism.
1.plane failure
2.wedge failure
3.Toppling failure
1.Plane failure:
Conditions or criteria for plane failure:
a. Strike of the hill slope and sliding plane must be similar within +- 20 degree.
b. The dip direction of sliding plane and hill slope should lie at same direction
c. The dip angle of sliding plane should be lesser than hill slope and must be greater than
angle of friction.

Fig: plane failure

2.Wedge failure:
When two plane intersects, a line of intersection is formed which is known as wedge line.
If block of rock fails through such line is known as wedge failure.
Criteria for wedge failure:
a. The trend of wedge must lie outward the hill slope.

18
 b. The plunge of line of intersection must be lesser than dip angle of hill slope and must be
greater than average friction angle.

fig: Wedge Failure

3.Toppling failure:
It occurs when column of base of rock rotates and falls outside the base of hill slope.
Criteria for toppling failure:

a. The direction of hill slope and discontinuity plane must lie opposite direction with respect
to each other.
b. The discontinuity plane must be steeply dipping. (more than 45 degree)
c. The C.G of the block of rock should lie outside the base of hill slope.

fig: Toppling Failure

19
 CHAPTER 4: STUDY OF MASS MOVEMENT

location 3
This location lies on the way to Malekhu to Mugling near trishuli river, at Krishna bhir.
Mass movement
Mass movement is one of the most challenging slope processes related to the potential
energy developed due to the gravitational stress may or may not influenced by the pore water
pressure. It refers as a whole a big mass moves outward and downward. Slope failure,
landslides, debris flow are the major mass movements phenomena. Ass the mechanism of
the mass movement differ the necessary treatment and stabilization measures are also
different from its complex type of mass movement are frequent in the area, which makes the
treatment more challenging.

fig: types of mass movement

CLASSIFICATION OF MASS MOVEMENTS

There are three major mass movement phenomena and they are listed below:

1) Landslides
2) Slope Failure
3) Debris Flow

20
1) Landslides
Large dimensional slow to sometimes rapid but continuous movement of large
weathered rock or solids on a clear slide surface are called the landslides. Sliding
surfaces usually contains clay and the activities are influenced by the ground
water. Treatments of the landslides are expensive and site specific. Effective
treatments of the landslides demand the geo-technical investigation of the
unstable area. Stability measures in the landslides are big challenging for many of
the civil engineering structures.

fig: Classification of Landslide according to Varnes (1978)

2) Slope Failure
Relatively small dimensions movements of the weathered rocks or soil layers in
the slopes are called the slope failures. It leads to more stable configuration may
redistribute the rock material in less steep slopes and it relief the stress by
reducing the high concentration of the stress usually present at the valley bottoms.
At the same time slope failure weakens the rock providing the already sheared
surfaces at the residual
strength, the reactivation of
instabilities as once failure
rock mass has not always
reached complete
stabilization. The slope
failure loosens the rock mass
and open the stress relief
joints or fractures. Cleaning
of the debris is considered as
the best solution in case of
Fig: slope failure
the slope failure along the

21
 road but it could sometimes lead to disaster landslides. Smaller magnitude slope
failure was generated in Krishna Bheer in the monsoon of 2000, which leads to
disaster landslides during the same year.

3) Flow/spread/creep
When the shear strength of the big slope material considerably reduced the rapid
movements of the solid earth materials including large volume of water can take
place. If the material is complex debris such phenomena are called debris flow. If
the flow is fine the phenomena is called odd flow. Sometimes the viscous materials
could spread down slope. The flow but continuous movement of the slope
containing the thicker soil, largely without any distinct slip surface is recognized as
creeping. Stability measures against the flow spread and creeping are complex and
demands considerably high costs.

Causes of Mass Movement

 High relief or steep slope

 Under cutting of banks by river (toe cutting)
 Presence of weaker rock such as slate, schist, mudstone
 Heavily fractured rock
 High grade of weathering of rock
 Concentrated precipitation and intense rainfall
 Seismic activities
 Improper land used
 Deforestation

Control measures of Mass Movement

1) Construction of retaining structures:
These are the walls are rigid walls which are used to support the soil mass laterally so
that the soil can be retained at different levels on the two sides. Following are the
types of retaining structures:
a) Gabion wall
b) Stone masonry
c) RCC wall or concrete wall
d) Crib wall
2) Rock bolting
3) Pile work
4) Slope treatment
a) Removable
b) Flatting

22
 c) Benching
5) Reduction of pore water treatment
a) Surface drain
b) Sub surface drainage
6) Erosion control mechanism
a) Construction of spur
b) Construction of dyke
c) Construction of check dams.
d) Stone pitching
7) Bio Engineering.
8) Good drainage
a) Cascading
b) Culvert

Here, Bio Engineering is the combination of engineering structures and vegetation.

Engineering structures are given above. Whereas for vegetation different types of plants can
be planted. The plants are so chosen that they are strong and will not affect other plants. The
engineering structures help to prevent mass movement up to its life span and until it the plants
gets fully developed and they hold together the soil particles and help to prevent mass
movement even after the failure of engineering structures.

fig: Structures to control mass movement

23
 CHAPTER 5: STUDY OF ROCK MASS CLASSIFICATION SYSTEM

Location 4
This location lies at about 700meter from our stay area. This site is located in downstream of
malekhu river on right bank of river.
Engineering Geological Data
There are some factors whose conditions in case of rock are observed and recorded
in order to determine the strength of the rock for laying foundations on it simply known as
engineering geological data. These data help us to determine the present condition and the
nature of the rock.
Importance of geological data
Purpose specific geological data collected from the field (rock mass) which can be
quantified and used as a design parameter. It is quantities diagnosis of an area. Site
investigation is the investigation of a particular area for specific purpose data collection. It is
very essential to draw an engineering geological map or to solve any geological problems.

Parameters of engineering geological data

1) Rock type
a) Sedimentary
b) Igneous
c) Metamorphic
2) Rock strength
a) High
b) Medium
c) Low
3) Weathering grade
a) Fresh water (w0)
b) Slightly weathered (w1)
c) Moderately weathered (w2)
d) Highly weathered (w3)
e) Completely weathered (w4)
f) Residual soil (w5)
4) Rock quality designation (RQD)
It is expressed in percentage. The expression for RQD is:
RQD=115-3.3*Jv
Where Jv = joint volume. I.e. number of joints per unit volume.
5) Spacing of discontinuity
It is expressed in cm and all the discontinuity is taken under considered area.
Aperture or separation of discontinuity

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 a) Tight (<1cm)
b) Open (expressed in cm, all the data are taken)
c) Wide (>30cm)

6) Infilling materials
Sand/silt/clay/calcareous material
7) Persistence (Condition of discontinuity)
8) Roughness of discontinuity
a) Smooth
b) Rough
c) Undulated
9) Orientation of joint set
These are the numbers of parallel or nearly parallel sets of the joints in the rock mass,
10) Orientation of joint set
Expressed including dip amount and dip direction, (i.e. dip amount/dip direction)
11) Ground water condition
a) Dry
b) Dripping
c) Seepage
d) Flowing
e) Damp/wet

ROCK MASS CLASSIFICATION SYSTEM

The rock mass classification system is the system of evaluating the composition and the
characteristics of the rock mass. The foundations stand on the rock and the properties of the
rock affects the stability of the foundation. The problems related to these things can be solved
by using the rock mass classification system. The system helps to estimate the strength and
the deformation properties of the rock mass. The large volume of rock intersected by the
discontinuities is known as rock mass. The rock mass is considered in between two
discontinuities. In civil engineering practice, rock mass is considered as construction site
where as rock is considered as construction materials. Rock mass as construction site provides
foundation for building, reservoir, base for road alignment etc.

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 Description of Rock mass classification system:
1) Terzaghi’s Rock mass classification
This classification is the earliest reference which is the descriptive classification:

 The rock with no joints: intact rock

 The rock with little strength along bedding surfaces: stratified rock.
 Rock mass jointed but cemented: moderately jointed rock.
 Jointed rock mass without any cementing of joints: blocky and seamy rock.
 Rock reduced to sand sized particles due to weathering: crushed rock
 Rock with clay: squeezing rock
 Rock squeezes primarily from mineral swelling: swelling

2) Deere’s Rock quality designation index (RQD)

D.U. Deere introduced a rock mass classification system based on the quality estimate of rock
mass quality from drill core logs.

𝑠𝑢𝑚 𝑜𝑓 𝑐𝑜𝑟𝑒 𝑝𝑖𝑒𝑐𝑒𝑠 > 10 𝑐𝑚

𝑅𝑄𝐷 = × 100%
𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑐𝑜𝑟𝑒

But in the absence of core logs,

𝑅𝑄𝐷 = 115 − 3.3𝐽 ,

Which is suggested by Palmston (1982) where Jv is the sum of the number of joints per unit length
of all discontinuities sets or simply the volumetric joint count.

3) Bieniawski’s Geomechanics Classification

Bieniawski in 1976 published the details of rock mass classification called the geomechanics
classification and widely known as rock mass rating (RMR) system. During the study of the
rock mass classification this method has been adopted.

Six basic parameters to classify the rock mass are used in this system:

1) Strength of the rock

2) Rock Quality Designation (RQD)
3) Spacing of the discontinuity
4) Condition of the discontinuity
5) Ground water condition
6) Orientation of the discontinuity
Different rating has been provided to different parameters and he sum of all these
parameters gives the final rating. The value of rating provides the class of the rock.

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 fig: Rock Mass Rating System (Bienlawski, 1989)

4) ROCK MASS CLASSIFICATION BASED ON RMR

CLASS NUMBER RATING VALUE ROCK QUALITY

I 100-81 Very good rock
II 80-61 Good rock
III 60-41 Fair rock
IV 40-21 Poor rock
V <21 Very poor rock

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ROCK TUNNELING QUALITY INDEX (Q Value)
Barton et.al (1974) proposed this theory. The value of Q varies on the logarithmic from 0.001
to 1000.Q value is defined by:
Q= (RQD*Jr*Jw)/(SRF*Ja*Jn)
Where RQD= rock quality designation
Jr = joint roughness number
Jw = joint water reduction factor
Jn =joint set number
Ja = joint alternation factor
SRF= stress reduction factor
According to the obtained Q-Value the rock mass is classified into nine class:

Q-Value Rock Mass Class

0.001-0.01 Exceptionally poor
0.01-0.1 Extremely poor
0.1-1 Very poor
1-4 Poor
4-10 Fair
10-40 Good
40-100 Very good
100-400 Extremely good
400-1000 Exceptionally good

OBJECTIVES OF ROCK MASS CLASSIFICATION

 Identify the most significant parameters influencing the behavior of rock mass.
 Divide a particular rock mass formulation into groups of similar behavior-rock mass
classes of varying quality.
 Provide a basis of understanding the characteristics of each rock mass class.
 Relate the experience of rock condition at one side to the conditions and experience
encountered at others.
 Derive quantities data and guidelines for engineering design.
 Provide common basis for communication between engineers and geologists.

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ENGINEERING SIGNIFICANCE OF ROCK MASS CLAASSIFICATION

 Improving the quality of site investigation by calling for the minimum input data as
classification parameters.
 Providing quantities information for design purposes.
 Enabling better engineering judgement and more effective communication on a
project.

fig: Selection of rock for RMR

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CHAPTER 6: PREPARATION OF ENGINEERING GEOLOGICAL MAP

location 5
This location lies at about 700 meters from our stay area. This site is located in
downstream of malekhu river on right bank of river.

Geological Map
A geological map is a special-purpose map made to show geological features. Rock units
or strata are shown by color or symbols to indicate where they are exposed at the
surface. Bedding planes and structural features such as faults, folds, foliations,
and lineation are shown with strike and dip or trend and plunge symbols which give these
features' three-dimensional orientations. Geologic maps are uniquely suited to solving
problems involving Earth resources, hazards, and environments. Geologic maps represent the
distribution of different types of rock and surficial deposits, as well as locations of geologic
structures such as faults and folds. Geologic maps are the primary source of information for
various aspects of land-use planning, including the sitting of buildings and transportation
systems. And perhaps most importantly such maps help identify ground-water aquifers, aid
in locating water-supply wells, and assist in locating potential polluting operations, such as
landfills, safely away from the aquifers.

Geologic maps are actually four-dimensional data systems, and it is the fourth dimension of
time that is crucial to assessing natural hazards and environmental or socio-economic risk. To
read a geologic map is to understand not only where materials and structures are located,
but also how and when these features formed.

Digital geologic maps are interactive electronic documents that put earth science issues into
geospatial frameworks. They capture the size, the shape, the depth, and the physical and
chemical contexts of earth materials, and they blend data display with the results of
interpretive research. The combination of geologic maps and GIS databases help us address
a great variety of complex geologic and hydrologic issues, such as: How does subsurface
distribution of porous and impermeable rock affect the flow of water, the potential for

30
contamination, and the volume available for use. There are basically two types of geological
map:

1) Surface Geological map

Surface geological map are compiled from surface geological data.

2) Subsurface Geological map

These are compiled from bore holes, well logs and geophysical survey data or it can also be
prepared by extrapolation of surface data.

fig: Engineering geological map

Field Equipment and tools:

Geological mapping requires a lot of small field equipment and tools such as:
a) Hammer and chisels
b) Compasses, clinometers and camera
c) Hard lenses and Tapes
d) Map cases and Field note books
e) Scales and Protractors
f) Acid Bottles and Hand gloves
g) GPS, pedometers and altimeters
h) Stereo net and stereoscopes.
In addition to these basic stationeries like pencil, erasers and a jack- knife are needed in the
field.

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Table for preparation of geological map of Road.

CHAINAGE BEARING(FB) Width ATTITUDE ATTITUDE

OF OF HILL
ROCK SLOPE

0+000 5.8 221/69

136

0+009 6.9 214/62

134

0+013 7.14 230/59

142

0+022 6.750 224/59

144

0+028 6.77 226/49

148

0+034 6.5 200/47

143

0+040 5.4 - -

113 -

0+044 5.4 - 173/40

86

0+05 5.7 159/55

Here,

Hill slope is S60E/60.

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fig: Geological map of Road.

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Scale
Small scale geological maps (1:50,000 and smaller) are suitable for researching issues such as
the prospectivity of a region, or regional scale structures, e.g. a fold belt.
Intermediate scale geological maps (1:50,000 to 1:5,000) include more detailed information
such as the outlines of prospects; regional-scale strike and dips; and larger structural elements
that control hydrocarbon accumulations (e.g. individual anticlines).
Large scale maps (1:5,000 and larger) offer details that would crowd-out a map of smaller
scale, such as sampling sites, dip and strike markings, small faults, outcrops. These maps are
generally used once a prospect has been identified and geologists have been into the field to
gather data. Their scale and content are designed to allow the size and shape of a
hydrocarbon or mineral body to be defined and understood.

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 CONCLUSION:
At last we can conclude that Malekhu area is the best place for geological curiosity. Because
in small area there is a lot of things to explore, and has large amount of the geological
phenomenon and hence provides broad knowledge for the new learners. The basic
knowledge that one engineer should have of geology can be found in Malekhu area.
Now, from this tour we have knowledge to identify the site selection criteria for a civil
structure. Also, this tour gave the knowledge about the mass movement, landslide and failure
mechanism of rock. We also learned to classify rock according to RMR system. very important
this tour helped us to learn, how to prepare geological map of road. This tour also helped to
take attitude of different geological structure like bedding plane or joint plane, which is
important to read any geological report.
At last it can be said that if there had not been any geological trip, we would not have learnt
a lot of these information as theoretical knowledge is not enough for field work. so this
geological field work helped us a lot to understand exactly why geology is important for an
civil engineer.
Finally, this tour has been successfully completed due to our respected teachers and our
college. So, we express heartily thank to them.

REFRENCES
 Data collected during the field visit.
 Sketches drawn and photos taken in the field.
 website: WWW.Wikipedia.com
 Book: Geology for civil Engineers, by Kabiraj Paudyal.
 Recent publications related to the subject matters and other sites.

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