Environmental Engineering Reference
In-Depth Information
experience of the investigator in the area. Do they have prior knowledge or is the area new
to them? This text basically assumes that prior knowledge is nil or limited.
2.2
Surface Mapping
2.2.1
General
Objectives
Data Base
For all sites it is important to determine the general geologic conditions and identify sig-
nificant development and construction constraints. For large study areas it is useful to pre-
pare a map illustrating the surficial and shallow geologic conditions.
Preliminary Site Evaluations
An overview of geologic conditions permits preliminary evaluations regarding the suit-
ability of the site for development. The first step is the identification of major geologic haz-
ards and “constraints” in the study area. Depending upon the construction or development
proposed, constraints could include shallow rock or water, or thick deposits of weak soils.
Taking into account the hazards and constraints, the optimum location for the proposed
construction is selected, and the planning of the site investigation then begins.
Methodology
A geologic reconnaissance study may advance through a number of steps as described
briefly in
Figure 2.1,
including:
Research of reference materials and collection of available data.
●
Terrain analysis based on topographic maps and the interpretation of remotely
sensed imagery.
●
Preparation of a preliminary engineering geology map (large land areas).
●
Site reconnaissance to confirm initial data, and, for large areas, amplification of
the engineering geology map, after which it is prepared in final form.
●
Preparation of a subsurface exploration program based on the anticipated
conditions.
●
2.2.2
Research Data
Basic Objectives
A large amount of information is often available in the literature for a given location. A
search should be made to gather as much data as possible before initiating any exploration
work, particularly when large sites are to be studied, or when the site is located in a region
not familiar to the design team. Information should be obtained on:
Bedrock geology,
including major structural features such as faults.
●
Surficial geology
in terms of soil types on a regional or, if possible, local basis.
●
Climatic conditions
, which influence soil development, groundwater occurrence
and fluctuations, erosion, flooding, slope failures, etc.
●
Regional seismicity
and
earthquake
history.
●
