Development of peat land and types of peat - Geotechnics of Organic Soils and Peat - page 36

Figure 2.15 Cross-section of piston sampler ( after Huat, 2004).
mechanism in the head allows only the upward movement of the piston rod, thus
preventing loss of the sample when the sampler is withdrawn from a borehole. A ball
cone clamp is typically used as a locking mechanism. Before each sample is taken, the
standard Japanese method of pre-augering down to the sampling depth is used. Special
care is exercised to make sure that the bottom of the borehole is clean and straight.
When sampling, the boring rod and the piston extension rod are connected while the
sampler is lowered smoothly to the bottom of the borehole. Details of the sampler are
presented in the article by Tanaka et al . (1996).
Seaby (2001) has presented a sampler designed not for geotechnical investigation
but for forestry. Despite this, it can be used to take undisturbed samples from medium
depths to obtain peat cores more than 1m long without compacting them. The sampler
is described as comprising two halves inserted separately (Figure 2.16). A length of
3.5mm thick PVC pipe, 80 or 110mm in diameter, is halved and the tip of each half
is chamfered and provided with a pointed, sharp metal blade attached to inside. On