PREPARATION OF WATER-SATURATED BENTONITE SAMPLES AND THEIR USE IN TORSION SHEAR TESTS

Abstract

The present study concerns cyclic shear tests on water-saturated bentonite samples. Since the tested bentonite is of sodium type, it absorbs water remarkably, and hence it is difficult and time-consuming to consolidate it for shear tests. This difficulty was overcome by inventing a new consolidation tank in which the drainage path is significantly shortened, and consequently the consolidation time is shortened. Cyclic torsion shear tests were performed on thus-prepared specimens to examine the variation of shear modulus and damping ratio with increasing shear strain amplitude. Moreover, cyclic shear stress was applied on an anisotropically consolidated specimen to demonstrate that permanent distortion of bentonite is small even during a very strong earthquake loading.