Determination of shear wave velocity in granular materials by shear vibration within discrete element simulation

Shear wave velocity is an important parameter to reflect the engineering properties of granular materials like sand. The measurement of shear wave velocity throughout the discrete element simulation is of great significance to understand the microscopic mechanism of variation of the mechanical properties. Numerical simulation of shear wave propagation using DEM is implemented by applying a velocity pulse to the transmitter in a certain direction and monitoring the corresponding average velocity of the receiver. The cross-correlation analysis is adopted due to its superiority of both determining the travel time and identifying similarities between two signals. The shear wave velocity is calculated using the wave travel time and the distance of the travel path, in exactly the same way as in laboratory tests. The influencing factors including excitation frequency, excitation amplitude, size of transmitter and receiver as well as damp are carefully analyzed, and reasonable values of the parameters for shear wave modeling are proposed. It is found that the appropriate excitation amplitude should be chosen on the basis of avoiding the generation of frictional work. It is also indicated that fruitful results will be obtained if both the radius of transmitter and receiver are chosen as one half of that of DEM specimen’s. The research results are verified through the outcomes of even-particle assemblies.