The GP sampler: a new innovation in core sampling

Kenji Mori and Katsuo Sakai

This paper introduces a new type of sampler called the GP sampler. It was designed to sample gravelly soils, but has proven to be successful in sampling soils ranging from dense sand, to gravel, as well as sedimentary rocks. The sampler is constructed of a single core barrel and uses a viscous polymer gel as its drilling fluid. The polymer plays a key role in obtaining high-quality samples, helping to preserve the soil structure. The polymer gel was also employed in more traditional style samplers, in an effort to improve the quality of samples obtained from silt, silty sand, and sand. In the field, GP samplers have been successful where other conventional methods have experienced difficulties or failed altogether. Although the GP sampler is not a perfect sampler, it is beginning to make a qualitative difference in the sampling of granular soils for engineering analyses.