Experimental study on cyclic simple shear behaviour of predominantly dilative silica sand

Abstract

This study investigated the cyclic behaviour of a severe dilative silica sand from Rudsar, Northern Iran, through simple shear tests. For this purpose, monotonic (constant volume/vertical stress) and cyclic (constant vertical stress) tests were performed on moist sand specimens prepared at initial relative densities of 20–60%, vertical stresses of 100–300 kPa, and cyclic stress ratios of CSR = 0.20, 0.25 and 0.30. These also included bender element tests to determine the small-strain shear modulus Gmax. An increase in initial relative density, vertical stress and number of loading cycles led to a nonlinear increase in the secant shear modulus Gsec, while the opposite was observed for increasing CSR. Moreover, increasing CSR improved the damping ratio, whereas increasing the initial relative density, vertical stress and/or number of loading cycles had negative effects on the damping ratio. Finally, the bender element test results showed that Gmax increased for increasing vertical stress and initial relative density.