Micromechanics of seismic wave propagation in granular materials

In this study high quality experimental studies on an analogue soil in a cubical cell are compared with discrete element simulations to investigate the propagation of waves through the soil sample from a grain-scale perspective. Examination of the data resulting from the two analyses confirms the complexity surrounding interpretation methods used for small-strain stiffness evaluation. Complex, but similar, responses to perturbations generated by bender/extender piezoceramic elements in experiments and controlled movement of particles in numerical simulations were observed. In both cases tests were repeated for a range of confining pressures and the system response was interpreted to give values of the shear and constrained moduli. At a given stress level, there was good agreement between the shear modulus values, however the laboratory test data gave higher constrained modulus values.