Effect of particle size and shape of sand on dynamic strength characteristics of the sand-geomembrane interface

This study experimentally investigates the dynamic behaviour of sand–High-Density Polyethylene (HDPE) geomembrane interfaces using a modified large-scale shear box mounted on a shake table. The influence of sand particle size and shape on interface response is systematically evaluated through cyclic shear tests under varying normal stresses, relative densities, loading cycles, and displacement amplitudes. Dynamic interface behaviour is characterized using dynamic coefficient of friction ( μ d ) , secant shear modulus ( G sec ) , and damping ratio ( D r ) . Results indicate that increasing particle size and angularity enhance μ d and G sec , accompanied by a reduction in D r . Increasing normal stress and relative density generally increase damping ratio and secant shear modulus, whereas the influence of loading cycles is most pronounced during the initial stages of shearing before progressively stabilizing. Empirical relationships are developed to predict damping ratio and secant shear modulus as functions of normal stress, displacement amplitude, and particle morphology. The proposed formulations successfully reproduce the observed interface response and provide predictive tools for evaluating sand–geomembrane interaction under cyclic loading.