1.
1 METHODOLOGY
Based on the objectives and scope of the consultancy services, an appropriate methodology
has been developed in order to address the various requirements of the project. Since the
scope of the services to be provided covers both independent and inter-dependent activities,
it has been proposed to adopt a Task Approach to ensure that the entire scope of services
is completed comprehensively and with reasonable accuracy.
1.1.1 Investigations for Bridges and Structures
1.1.1.1 Inventory and Condition Survey for Bridges and Culverts
Inventory and condition survey of culverts, bridges and other structures shall be done to
ascertain the need for reconstruction / widening and rehabilitation of these structures. The
condition assessment of bridges will be carried out by Senior Bridge/Structural Engineer in
accordance with guidelines given in IRC-SP:35-1990. The data shall include construction
details, type of foundation, substructure and superstructure, details of span, waterway,
design loading and functioning of the structure in the past, both from hydraulic and structural
considerations.
1.1.1.2 Hydraulic and Hydrological Investigations
These studies will be carried out in accordance with IRC Special Publication No.13
(Guidelines for the design of small bridges and culverts) and IRC:5-1998 (Standard
Specifications & Code of Practice for road, bridge section 1 - General features of design).
These investigations will be carried out for all existing drainage structures along the road
sections under the study. Its quality will be ensured by:
Collection of data by an experienced engineer
Its correct interpretation based on experience, site inspection and behaviour of other
structures across such streams in the near vicinity by such experienced engineers.
For HFL, reliance will be placed on past records, local enquiries and flood marks on
structures in the vicinity.
For road sections getting overtopped during heavy rains will be placed on local enquiries.
Geo-technical investigations will be carried out for determining engineering characteristics of
subgrade soil, the sub-soil underlying the foundations of the proposed bridges and other
structures, etc. as per IRC 78-2000 and underneath the road pavement.
Appropriate field tests will be conducted and boreholes drilled at selected locations as
indicated in the TOR. The minimum scope of geo-technical investigations for bridge
structures is:
Procedure
Quality Assurance requires that activities at every stage of geo-technical and material
investigations shall be carried out strictly in accordance with the procedures prescribed in
the relevant codes, so that the results of these investigations reflect truly the sub-soil and
material characteristics.
Every geo-technical and material investigation will be carried out and completed principally
in four sequential stages, namely:
a) Field Investigations
b) Sampling
c) Laboratory Testing
d) Report Preparation
While the investigations will be carried out by competent technical staff comprising trained
technicians and well qualified engineers, the Materials and Geo-technical Engineer will pay
periodic visits to the boring sites. An experience geo-technical Engineer will be posted at
site for the entire duration of the boring work to have constant check.
The results of the investigations as furnished by the sub-consultants shall be examined by
the Materials and Geo-technical Engineer for consistency and compatibility before
acceptance.
Standards to be followed for testing
i) In Situ Testing
Standard Penetration Test (SPT)-IS:2131
Collection of Samples – IS:1892, IS:2132
ii) Laboratory Testing
Tests on Soil Samples
Visual and Engineering Classification – IS 1498
Sieve Analysis and Hydrometer Analysis-IS:2720, Part IV
Liquid and Plastic Limits-IS: 2720, Part V
Specific Gravity-IS: 2720, Part III
Proctor Compaction Test-IS:2720, Parts VII and VIII
Field Density-IS: 2720, Parts VII, VIII and IX
Field Moisture Content-IS: 2720 Part II
Unconfined Compression Test-IS: 2720, Part X
Direct Shear Test-IS: 2720, Part XIII
Triaxial Shear Tests:
Unconsolidated Undrained (UU) Test-IS: 2720, Part XI
Consolidated Undrained (CU) Test-IS: 2720, Part XII
Consolidation Test-IS: 2720, Part XV
Cholride and Sulphate test
