Determination of constitutive parameters of filled joints under repeated impact loads using indirect inversion method

This study first experimentally investigated the deformation behavior of artificially filled rock joints under repeated impact loading. Subsequently, a method was proposed to indirectly obtain the parameters of constitutive model for filled joints through waveform inversion. Finally, the influences of the number of impacts, filling moisture content, and filling thickness on the parameters of the constitutive model of filled joint were examined. The results indicate that the proposed indirect parameter inversion method is effective. It overcomes the difficulties encountered when handling large deformation filling materials. Repeated impacts compact the filling material resulting in changes in the deformation characteristics of the filled joints. Specifically, the initial normal stiffness increases linearly with an increase in the number of impacts, while the maximum allowable closure decreases exponentially. The initial normal stiffness first increases and then decreases with an increase of moisture content, whereas the maximum allowable closure of the joint increases approximately linearly with increasing moisture content. The increasing filling thickness results in a linear increase in the initial normal stiffness and a linear decrease in the maximum allowable closure.