A Three-Dimensional Grouting Model Considering Hydromechanical Coupling Based on the Combined Finite-Discrete Element Method

Abstract In this paper, we present a three-dimensional (3D) grouting model based on the combined finite-discrete element method (FDEM). The 3D grouting model discretizes the problem domain into tetrahedral elements and joint elements, and the grout flows only in the broken joint elements, which satisfies the planar Poiseuille flow. By combining grout migration, FDEM mechanical cracking computation, and stress-induced fracture aperture variation in a graphics processing unit (GPU) parallel multiphysics FDEM software, called MultiFracS, the 3D grouting model can model rock cracking and the effect of hydromechanical (HM) coupling. First, a grouting example with analytical solutions is presented to validate the 3D grouting model. Then, we investigate the influence of several key parameters on grout penetration in fractured rock masses. The results reveal that the 3D grouting model can model grout migration, pressure distribution, grout–rock mass interaction, rock deformation, and crack initiation and propagation. Finally, the evolution of fracture geometry induced by grouting under different in situ stresses is studied. The numerical results present high coincidence with the in situ experimental results, demonstrating that the 3D grouting model is effective in dealing with fracture grouting.