Comparison between Shear Strength of Dry Sand Measured in CSS Device using Wire-reinforced Membranes and Stacked Rings

ABSTRACT: The cyclic simple shear test (CSS) is widely regarded as the preferred element test for liquefaction because it best simulates vertically propagating shear waves. The CSS test provides reliable, high-quality laboratory data for model development and calibration in Geotechnical Earthquake Engineering design. Direct simple shear (DSS) tests can be performed by using the same apparatus to measure the shear strength and define the failure envelope. The consolidation and shearing are performed under K0 conditions. The K0 conditions are maintained through lateral confinement that prevents lateral deformations. Wire-reinforced membranes (WR) and stacked rings (SR) have been the two major techniques used to achieve the no lateral strain condition. The motivation for this work was to study the effect of using a WR versus SR on the stress-strain behavior and shear strength of clean sand. The paper presents results from DSS tests performed on Monterey #0/30 and Washed Mortar sands. The tests were performed under a constant vertical stress instead of constant volume to monitor effect of the confinement systems on the contractive and dilative response of the sand samples. The results show that there is general agreement between the measured shear strength and volumetric response with SR and WR confinement systems