Geotechnical Engineering

DHARM

SOIL EXPLORATION 751

a good report. A report writer should be knowledgeable, practical and pragmatic. No theory,
books or codes of practice can provide all information required to produce a good report. It is
only the experience of a number of years of dedicated service in the field that helps a geotechnical
consultant to make the report writing an art.

A good soil exploration report should normally comprise the following:

1. Introduction, which includes the scope of the investigation.


2. Description of the proposed structure, the location and the geological conditions at
   the site.


3. Details of the field exploration programme, indicating the number of borings, their
   location and depths.


4. Details of the methods of exploration


5. General description of the sub-soil conditions as obtained from in-situ tests, such as
   standard penetration test and cone penetration test.


6. Details of the laboratory tests conducted on the soil samples collected and the re-
   sults obtained.


7. Depth of the ground water table and the changes in water levels.


8. Analysis and discussion of the test results.


9. Recommendations about the allowable bearing pressure, the type of foundation of
   structure.


10. Calculations for determining safe bearing pressure, pile loads, etc.


11. Tables containing bore logs, and other field and laboratory test results.


12. Drawings which include an index plan, a site-plan, test results plotted in the form of
    charts and graphs, soil profiles, etc.


13. Conclusions. The main findings of investigations should be clearly stated. It should
    be brief but should mention the salient points.

Limitations of the investigations should also be briefly stated.
A sub-soil investigation report should contain the data obtained from bore holes, site
observations and laboratory findings along with the recommendations about the suitable type
of foundation, allowable soil pressure including anticipated settlements, and expected behav-
iour of the foundation.

If the recommended types of foundation requires any special attention during construc-
tion phase, like dewatering and/or bracing, it should be so stated and the client should be
cautioned about the problems that might arise during construction phase.

It is essential to give a complete and accurate record of the data collected. Each bore
hole should be identified by a code number. The location of each bore hole should be fixed by
measurement of its distance or angles from some permanent features in the vicinity. All rel-
evant data for the bore hole is recorded in a boring log. A boring log gives the description or
classification of various strata encountered at different depths. Any additional information
that is obtained in the field, such as soil consistency, unconfined compression strength, stand-
ard penetration number, and cone penetration value, is also indicated on the boring log. It
should also show the position of water table. If the laboratory tests have been conducted, the