Evaluation of sample disturbance of three Norwegian clays

Abstract

The quality and reliability of laboratory test data in sensitive clay can significantly be affected by sample disturbance. In turn, sample disturbance may affect key design parameters such as compressibility, preconsolidation stress and undrained shear strength. In this work, samples obtained from a 72 mm thin walled fixed-piston sampler are compared to Sherbrooke Block samples with diameter (Ø) of 160 mm (mini) and 250 mm (standard) for clays from three different locations in Norway (Skatval, Koa and Nybakk-Slomarka). All three clays have plasticity indices varying between 8-25 and water contents varying between 30-40%. Results from triaxial tests (CAUC) and oedometer tests (CRS) are used to study the influence of sampler type and disturbance effect. Sample disturbance from both block samplers is further evaluated using measurements of shear-wave velocity (Vs) performed in the field and in the laboratory. The measurements are correlated to volumetric change values during triaxial testing as a form of evaluating quality of the laboratory tests.