Effect of high frequency excitation cycles on shear moduli and damping of dry silty sand

Abstract

The objective of the current research is to examine the effect of large number (up to half a million) of high frequency (30–100 Hz) excitation cycles on shear moduli and damping of dry silty sand with varying percentages (0–70 %) of non-plastic fines (NPF). Resonant column (RC) tests were performed with a provision of vibrating the specimen to a large number of excitation cycles for different values of confining pressure, relative density (RD), and shear strain amplitudes. The study invariably reveals that for chosen relative density in the range of 55–75 %, a continuous reduction in shear modulus along with an increase in the damping ratio of silty sand occurs with an increase in the number of excitation cycles. This finding is on account of an increase in the shear strain with an increase in the number of excitation cycles. At a given RD, an addition of NPF leads to a further reduction in shear moduli and an increase in the damping. This observation is primarily attributed to an increase in the void ratio of silty sand with an addition of NPF.