Geology Reference
In-Depth Information
Figure 4.22 Shell and auger rig in action, Leicester, UK. Casing, used to support the hole, is standing
out of ground and a shell is being dropped down hole to excavate further. In the foreground is a
U100 sampling tube attached to a down-hole hammer, ready for placing down hole and taking a
sample once the hole has been advanced to the required depth. Leaning against the wheel is one of the
drillers and also a trip hammer for SPT testing
-
also awaiting use at appropriate depths and changes
in strata.
laboratory testing and in situ strength tests at perhaps 1.5m intervals
or changes in strata. The standard penetration test (SPT) is commonly
used to measure strength, as discussed below under in situ testing.
Vane tests might be carried out rather than SPTs, especially in clay
soils. USA practice for investigating and sampling soils is described by
Hunt (2005). One cheap and quick way of sampling/testing is to use
wash boring, whereby the hole is advanced by water jetting as rods are
rotated. SPT tests, and possibly other samples, are taken at intervals.
None of these methods gives continuous sampling, so geological detail
may be missed.
 
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