A Numerical Study on Rate-Induced Strength Enhancement in Sand

Rate-dependent shearing response of sand has been of major concern for several geotechnical applications related to dynamic compaction, mine blasts, pile driving and rapid load testing of piles, etc. In this regard, transient laboratory tests indicate that the mechanical behaviour of sand may vary significantly when the applied strain rate ranges from 10^–5/s to 1/s or even higher. Such rate-dependent response of sand depends on the employed strain rate range along with sand morphology, stress and density state. In the present study, a recently proposed elastic-visco-plastic model by Mukherjee et al. (Mukherjee et al. in Acta Geotech 16:93–111, 2021) has been adopted for the assessment of rate-dependent mechanical behaviour of three different types of sand, i.e., crushed coral, silica and Toyoura sand. The predicted rate-dependent shearing response has been noticed to be in close agreement with the experimental observations from literature and the employed model aptly captures the rate effects in different sand types by altering the appropriate model parameters. All the three sand specimens have been subjected to the drained triaxial shearing at a same density and confining pressure, and the rate-induced strength enhancement has been assessed in terms of peak shear stress, peak friction angle and axial strain at peak.