Laboratory evaluation of dynamic shear response of sand – geomembrane interface

The seismic stability of geosynthetic structures incorporating soil-geomembrane interfaces depends largely on their response to dynamic loads caused by earthquakes or traffic. The present study investigates the dynamic shearing response of sand-smooth geomembrane interface through fixed block-type shake table tests. The influence of dynamic loading parameters, like sliding velocity, loading frequency, normal stress, displacement amplitude and the number of cycles, and relative density of sand on the shearing behavior of the sand-geomembrane interface, are examined. Results show that the peak cyclic shear stress is significantly influenced by normal stress, shear displacement amplitude, loading cycles, and relative density of sand. The dynamic coefficient of friction of the sand-geomembrane interface displays an increasing trend with an increase in loading frequency, shear displacement amplitude, and relative density of sand but decreases for the rest of the considered parameters. The shape of the hysteresis loops is dependent on the normal stress and displacement amplitude. The dynamic coefficients of friction are also compared with the corresponding values under static conditions. The results from the present study emphasize the importance of considering the design basis value of the dynamic coefficient of friction for each parameter during the design stage of geosynthetic structures involving sand and geomembrane.