Contribution to the micromechanical analysis of compression wave propagation in a granular medium

This paper presents a two-dimensional Discrete Element Method (DEM) investigation of compression wave propagation in a granular soil deposit subjected to a harmonic base excitation. Unlike classical continuum-based approaches, the proposed micromechanical model explicitly accounts for the nonlinearity produced by intergranular interactions. Analysis of the results indicated that the model accurately captures the well-established essential features of the response of a base-excited deposit, such as the motion amplification at the free surface, resonance phenomena, and the degradation of the deformation modulus at large strain levels. Furthermore, the model allowed for the estimation of the strain level at which the degradation of the deformation modulus becomes clearly visible; this level is in good agreement with levels obtained from previous physical experimental work. Furthermore, this study showed that the critical strain value that triggers nonlinear behavior or degradation of deformation moduli is of the same order of magnitude, whether in shear or compression.