Geology Reference
In-Depth Information
B
Figure 4.5
Example of
situations where a
single borehole (or
few boreholes)
might miss
important
information that
will affect the
integrity of the
structure.
B
Soft stratum
missed by
borehole
(perhaps as
lost core)
Borehole meets usual criteria in terms of depth
is best to take one or more boreholes even deeper if important to the
design.
Guidance on procedures and methodologies for site investigation is
given for the UK by Clayton et al. (1995) and for the USA and
more broadly by Hunt (2005). The British Code of Practice for Site
Investigations, BS 5930 (BSI, 1999), provides comprehensive advice on
procedures and techniques and for soil and rock description for
the UK. Other codes exist for different countries (e.g. Australia,
China and New Zealand). Generally, there is consistent advice over
the overall approach to site investigation, although terminology and
recommended techniques differ. All agree, however, that the
rst step
should be a comprehensive review of all available maps and documents
pertaining to a site
-
this is called a desk study.
4.3.2 Desk study
For any site, it is important to conduct a thorough document search.
This should include topographic and geological maps. Hazard maps
are sometimes available. These include broad seismic zoning maps for
