Environmental Engineering Reference
In-Depth Information
Phase No
Broad activities
1
DEFINE OBJECTIVES
ASK QUESTIONS
2
COLLECT & ASSESS EXISTING DATA
EVOLVE TENTATIVE SITE MODEL
3
PLAN WORK TO FILL IN
GAPS COMPILE ACTIVITY
CHART & COST ESTIMATES
4
FIELD, LABORATORY & OFFICE STUDIES
JUDGEMENTS & ANALYSES
PROGRESSIVELY ANSWER QUESTIONS
COMPILE GEOTECHNICAL MODEL(S)
ALL QUESTIONS ANSWERED
Figure 4.1.
Activity flow in site investigations.
either logical sequences or concurrently and to integrate their results. Answers to the purely
geological and geotechnical engineering questions are produced progressively from the
results, by combinations of analyses and judgements. Sometimes, new questions arise and
extra work has to be planned and approved (see arrow back to Phase 3). The site geotech-
nical model, and in some cases more detailed models for particular project features e.g.
dam, spillway, outlet works and quarry, are compiled.
When all questions have been answered with sufficient confidence, the investigation is
complete. Until then, further cycles of investigation are carried out until the required lev-
els of confidence are reached. The principle of 'diminishing returns' is applied.
4.4
PROGRESSION FROM REGIONAL TO LOCAL STUDIES
The geological studies in Phases 1 to 4 start with consideration of the site location in rela-
tion to the global tectonic situation, and should include study of the geology of a broad
region surrounding the site. This is necessary to assess the effects on the project of large
scale processes, some of which (
Table 4.2
) may have potential to damage it.
The regional geological studies are followed by geological and geotechnical engineering
studies at and near the site, on intermediate and detailed scales. The objectives and usual
activities of the regional and detailed studies are set out below, generally following ISRM
(1975). More detailed descriptions and discussion of the various activities are presented
in Chapter 5.
