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

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 verticalstress) tests were performed on moist sand specimens prepared at initialrelative densities of 20-60%, vertical stresses of 100-300 kPa, and cyclicstress ratios of CSR = 0.20, 0.25 and 0.30. These also included bender elementtests to determine the small-strain shear modulus G(max). An increase in initial relative density, vertical stress and number of loadingcycles led to a nonlinear increase in the secant shear modulus G(sec), while the opposite was observed for increasing CSR. Moreover, increasing CSRimproved the damping ratio, whereas increasing the initial relative density,vertical stress and/or number of loading cycles had negative effects on thedamping ratio. Finally, the bender element test results showed that G(max) increased for increasing vertical stress and initial relative density.