Geology Reference
In-Depth Information
trial pit logs
In this appendix, examples are presented of borehole (or drillhole) and
trial pit logs from the UK, Hong Kong and Australia. Locations have
been omitted in some examples. They contain a great deal of informa-
tion, not only as records of the ground conditions encountered but also
on the way in which the investigation was conducted, the machinery
used, the tests conducted and their results and the groundwater con-
ditions. These serve to illustrate the variety of use of descriptive terms
and classi
cations in description as well as typical techniques used in
ground investigation.
D.1 Contractor
s borehole logs
'
Contractor
s logs are carried out following standards and codes in the
country where the work is carried out. As discussed in
Chapter 4,
they
tend to provide somewhat simpli
'
ed descriptions of ground condi-
tions. The engineer who, unlike the contractor, has designed the GI
should have carried out a thorough desk study and be aware of the
factors that will be crucial to the success of a project; he may need to
examine samples himself to ensure that key features at a site have been
correctly identi
ed, described and highlighted.
D.1.1 UK example
The borehole log D1 is courtesy of Geotechnics Ltd. and for a hole
taken to 20m depth. Descriptions of soil and rock encountered are to
BS 5930:1999.
All of the following detail (andmuchmore) can be read directly from
the log without any report or further explanation.
The
first 1.2m was excavated as an inspection pit. This is usual
practice, just in case there might be services such as electric cables or
pipes not identi
ed on plans or using detecting equipment. Water was
encountered at 0.4m.
A cable percussion rig was then used to advance a hole of 0.15m
diameter. The hole was advanced essentially following the strategy
