Field sampling and testing - Geotechnical Investigation and Design Tables - page 39

Field sampling and testing

4.1 Types of sampling
•

The samples are recovered to classify the material and for further laboratory
testing.

•

Refer Chapter 1 for the effect of size of sampling and disturbance.

Table 4.1 Types of sampling.

Sample type Quality Uses

Disturbed Low Samples from the auger and wash boring, which

may produce mixing of material. Complete
destruction of the fabric and structure. Identify
strata changes.

Representative Medium Partially deformed such as in split barrel sampler.

Fabric/Structure, strength compressibility and
permeability expected to be changed.
Classification tests.

Continuous Medium/high Hole is advanced using continuous split barrel

or tube sampling. Obtains a full strata profile.

Undisturbed High Tube or Block samples for strength and

deformation testing. Tube samples are obtained
from boreholes and block samples from test pits.

- Disturbed samples obtained from augers, wash boring returns on chippings
from percussion drilling.
- Split barrel sampler used in the standard penetration test (SPT).
- Tube samplers are usually thin walled with a cutting edge, but with piston
samplers in soft to firm material.
- Undisturbed tube samples are not possible in sands, and split barrel sampling
is used.

4.2 Boring types
•

Various operations are used to advance the borehole, before obtaining samples.

•

Hole clean outs are required before sampling.