Coupled hydro-mechanical model for fractured rock masses using the discontinuous deformation analysis

• A coupled hydro-mechanical (HM) model is presented with the DDA-FDM approach.
• The mechanical response is studied by DDA and the steady flow is studied by FDM.
• The flow rate changes when the rock caverns are excavated based on HM model.
• Differences between the HM coupled model and the uncoupled model are shown.

A coupling analysis model is proposed to study the hydro-mechanical response of the fluid flow in fractured rock mass with the method of discontinuous deformation analysis (DDA). The DDA coupled hydro-mechanical model is interpreted in details by expressing the fracture fluid flow equations, the coupling process and the global coupled equations. For the mechanical response, the hydraulic pressure is determined first, followed by the coupled motion equations expressed under the DDA framework, to study the interaction between the fluid flow along the fractures and the movement of the rock blocks. In the fluid flow analysis, the cubic law is applied to study the steady flow along the fractures using the finite difference method (FDM). A real case of cavern excavation is analyzed by the proposed DDA coupled 2D hydro-mechanical model, to study the influence of fluid flow on the rock cavern stability during the excavation phase. The results show that the DDA coupled hydro-mechanical model is suitable for the stability and seepage analysis of practical engineering problems.