ABSTRACT
They are earning a reputation for collecting high quality sample. Diameter of the sample obtained from both samplers exceeds 20 cm which make them expensive in comparison with other conventional tube samplers. Therefore, their use is restricted only in researchworks or special projects. JPN, ELE100 and NGI54 samplers are a stationary piston type sampler but the geometry of their sampling tube is slightly different as shown in the table. ELE100 sampler has the largest inside diameter whereas NGI54 sampler has the smallest. NGI54 sampler has the thickest wall because it is a composite sampler consisting of outer and inner tubes (Andresen and Kolstad, 1979). Sampling using this sampler is usually carried out by so-called “displacement method”, where the sampler is directly penetrated at the desired sampling depth without borehole. In this study, however, a boreholewas driven even for the NGI54 sampler as well as for other samplers. Shelby tube is the most common sampler used in the world. It does not have a piston and is made up of mild steel. Sampling was carried out by the same Japanese driller to avoid difference for the skill of the driller in the sample quality. More information on sampler and sampling are given byTanaka et al. (1996) andTanaka (2000).
