Parallel laboratory tests have been carried out on high-quality block samples and ordinary piston tube samples from 12 deposits of soft Norwegian marine clays.
It is observed that the quality of samples indicated by suction measurements is similar to that inferred from the normalised change in void ratio (Δe/e 0) criterion.Īfter many decades of research, the issue of sample disturbance is still important as regards to determining reliable and representative soil parameters for foundation design in soft clays. The 5 o displacement sampler provides the highest suctions on the Ballinasloe samples. Suctions measured on the Japanese 75mm samples are similar to those measured on the block samples. In terms of sample quality the Sherbrooke block samples consistently exhibit higher suctions than the 76 mm, 54 mm and continuous soil samplers for the Onsøy test site. The Japanese and University of Massachusetts Amherst suction probe techniques provide relatively quick and consistent suction measurements, requiring less than half an hour to stabilise. Most of the techniques tested gave comparable results, although the cell pressure loading method provided the most variable measurements. A number of suction measuring techniques are reviewed and examined on samples of varying quality from two well-characterised soft clay sites, Onsøy in Norway and Ballinasloe in Ireland. The objective of this work is to examine the feasibility of using suction measurements for sample quality assessment.
This suction may vary depending on the degree of disturbance induced during the sampling process. Soil samples removed from the ground during sampling possess a suction in their unconfined state.
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