Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 3 IN-SITU GEOTECHNICAL TESTING
Figure 3.2(b) Sequence of Driving Split-Barrel Sampler During the Standard Penetration Test
Correlations between SPT N value and soil (Fig. 3.3 refers) or weak rock properties are wholly
empirical, and depend upon an international database of information. Because the SPT is not
completely standardised, these correlations cannot be considered particularly accurate in some
cases, and it is therefore important that users of the SPT and the data it produces have a good
appreciation of those factors controlling the test, which are:
1. Variations in the test apparatus;
2. The disturbance created by boring the hole; and
3. The soil into which it is driven.
March 2009 3-3