Effect of Sampling, Size, and Storage on Test Results for Marine Clay
SourceConsolidation tests on a soft marine clay formation indicated that it was normally consolidated when the tests were performed on cores obtained with a 2-in.-diameter (54-mm) tube sampler and overconsolidated by 0.16 tons/ft2 (kg/cm2) when the tests were performed on cores obtained with a 5-in.-diameter (124-mm) tube sampler. From comparative tests on 20, 40, and 60-cm2 test specimens trimmed from a block of stiff overconsolidated marine clay, the maximum preconsolidation pressures were measured on the 40-cm2 size. Storing the block sample in a humid room at 55 F for one and a half years decreased the measured preconsolidation pressure. Coating the consolidometer rings with Teflon and molybdenum-disulphide-based grease was effective in reducing side friction.
Triaxial strength tests with pore pressure measurements were performed on the soft marine clay, sampled with both 2-in.-diameter (54-mm) and 5-in.-diameter (124-mm) tube samplers. Although the measured strengths were comparable, the tests on specimens trimmed from the 2-in.-diameter (54-mm) cores produced greater strains to failure and a smaller pore pressure parameter A than did tests on specimens from the 5-in.-diameter (124-mm) cores.