Environmental Engineering Reference
In-Depth Information
4.2
GEOTECHNICAL INPUT AT VARIOUS STAGES OF PROJECT
DEVELOPMENT
Most dam projects develop in five more or less distinct stages as set out on Table 4.3.
Geotechnical input is required in all stages. Table 4.3 summarizes the broad objectives of
the geotechnical work and the usual activities and reporting needed, during each stage.
Table 4.3.
Geotechnical input during stages of development of dam project.
Stage No.
Name
Objectives and activities (Geotechnical)
1
Pre-feasibility
Assist in the selection of possible sites and obtain enough
understanding of the geological situation to plan the feasibility
and site selection studies. Usually includes review of existing
data plus a short ground and sometimes air inspection.
2
Feasibility and site
Assess the project feasibility and design from the geotechnical
selection
viewpoint, considering both the regional and local geological
situations. Explore alternative sites for dam and other key
structures, and adopt the most promising sites. Explore these
further if necessary to confirm feasibility and provide sufficient
data for preliminary design and feasibility stage cost estimate.
Provide regular progress reports and prepare formal report
at the end of Stage 2 with a definite statement confirming
(or otherwise) the project feasibility from the geotechnical
point of view.
3
Design and
Answer any questions outstanding or arising from the
specification
feasibility studies, and additional geotechnical questions
raised during the design. Further site exploration and testing
are usually necessary. Provide regular progress reports, and
report for tenderers or construction agency. Provide
assistance in the design of the embankment and other
structures and preparation of the specification.
4
Construction
Ensure that the geological picture exposed during construction
is as assumed in the design and if not, that modifications
are made to the design, if necessary. Provide day to day
advice on geotechnical matters to the resident engineer.
Provide record of geological exposures during construction
and of any rock movements, water inflows, etc. in regular
progress reports. This data is vital to the Surveillance Group
(see Stage 5); should any malfunction develop it may form the
main basis for (sometimes rapid) correct action. Activities
include detailed mapping, colour photography, review of
inspector's records, installation and reading of instruments,
monitoring simple tell-tales, etc. Input to design and
specification modifications to suit site conditions.
5
Operation
Ensure that the structure is performing as designed, from the
geotechnical point of view, and assist in the design of
remedial measures, if it is not. Inspect the completed
structure, the site area and records from instruments and
operator's observations, at regular intervals, preferably as a
member of a surveillance committee, including representatives
of design, construction and operation branches. Should any
malfunction be evident, assist in design of remedial measure.
This could involve conducting further site investigation and/or
analysis of the geotechnical records from Stages 1 to 5.
