724Chapter 18
SOIL EXPLORATION
18.1 INTRODUCTION
A fairly accurate assessment of the characteristics and engineering properties of the soils at a
site is essential for proper design and successful construction of any structure at the site. The
field and laboratory investigations required to obtain the necessary data for the soils for this
purpose are collectively called soil exploration.
The choice of the foundation and its depth, the bearing capacity, settlement analysis
and such other important aspects depend very much upon the various engineering properties
of the foundation soils involved.
Soil exploration may be needed not only for the design and construction of new struc-
tures, but also for deciding upon remedial measures if a structure shows signs of distress after
construction. The design and construction of highway and airport pavements will also depend
upon the characteristics of the soil strata upon which they are to be aligned.
The primary objectives of soil exploration are:
(i) Determination of the nature of the deposits of soil,
(ii) Determination of the depth and thickness of the various soil strata and their extent
in the horizontal direction,
(iii) the location of groundwater and fluctuations in GWT,
(iv) obtaining soil and rock samples from the various strata,
(v) the determination of the engineering properties of the soil and rock strata that affect
the performance of the structure, and
(vi) determination of the in-situ properties by performing field tests.
18.2 SITE INVESTIGATION
‘Site investigation’ refers to the procedure of determining surface and subsurface conditions in
the area of proposed construction. Thus, this term has a broader connotation than ‘soil
exploration’, and includes the latter.
Information regarding surface conditions is necessary for planning construction
technique. Accessibility of a site to men, materials and equipment is affected by the surface