A comparative study between the NGI Direct Simple Shear apparatus and the Mikasa Direct Shear apparatus

A comparative study of the NGI Direct Simple Shear Test (DSST) and the Mikasa Direct Shear Test (DST) is reported. Samples from Norwegian Drammen clay and Japanese Ariake clay were subjected to both types of test. An evaluation of these test results and a theoretical consideration on the different shearing mechanisms has shown that although the DST give generally higher stiffness and strength than the DSST, these differences can mainly be accounted for by the different shearing mechanisms and shearing rates. Sample disturbance due to transportation and handling may also be the reason for some of the difference. A technique for evaluation of sample disturbance in the DSST is presented and evaluated. Tests on undisturbed and remoulded Drammen clay consolidated to stresses much higher than the in situ effective overburden stress give almost identical results. Thus the effects of sample disturbance and in situ structure in the clay were eradicated.