Simulation of grout diffusion in fractured rock mass by equivalent seepage lattice elements

There are a large number of discontinuities in underground rock masses with different geometric properties, inducing complex grout diffusion processes. Classical discrete models commonly necessitate fine meshes to explicitly model these discontinuities and result into great computing efforts. In this work, a seepage lattice element model is proposed, which models the fissure seepage by pore seepage in equivalent pipes. We use the new model to study the horizontal grouting cases, considering diffusion as well as solidification processes of Bingham fluid. Some patterns are found: (i) The lattice elements do not need complex discretization which properly capture the grout diffusions processes; (ii) The diffusion of grout will become steady after reaching a specific distance from the injection point where the rock domain full of grout is the diffusion range; (iii) Crack openings, injection pressure and shear strength significantly influence this diffusion range. The proposed method and revealed rules can assist engineers to control the diffusion range and optimize the designs.