Simulation of coupled hydro-mechanical interactions during grouting process in fractured media based on the combined finite-discrete element method

Fracture grouting is one of the most widely used methodologies to reduce the hydraulic conductivity and enhance the strength of rock masses in geotechnical engineering (e.g., mining, civil engineering and hydraulic engineering). Understanding and controlling the migration process of grout slurry are critical to optimize the grouting process. In this paper, a grouting process simulator is generated for hydro-mechanical (HM) coupling grouting problems, linking the combined finite-discrete element method (FDEM) and a grouting flow simulator, called as FDEM-grouting. The initiation and propagation of fractures as well as the deformation of solid mass are solved by the FDEM. Meanwhile, the grout flow in fractures is modeled based on the principle of the parallel plate model. This FDEM-grouting can consider the HM coupling effect, the stress-induced fracture aperture variation, the fracture networks evolution and the hardening of grout during the grouting process, which are rarely considered in previous studies. The present FDEM-grouting is validated by intensive numerical tests. Then, several influence factors of grout penetration are discussed. Lastly, we investigate a fracture grouting process with considering the effect of in-situ stress and the interference between grouting holes. Results show that this FDEM-grouting is potentially useful to optimize the fracture grouting process.