Three Dimensional Simulation of Fluid-Driven Frictional and Tensile Ruptures on Existing Discontinuities

We present an implicit, fully-coupled hydro-mechanical solver for the three-dimensional simulation of fluid-driven rupture propagation along pre-existing discontinuities. The solver simultaneously handles frictional slip and tensile failure along arbitrary intersecting fractures and faults in a linearly elastic and impermeable rock matrix. Spatial discretization combines a displacement discontinuity boundary element method with a Galerkin finite element method for pore-fluid pressure diffusion. Frictional and tensile failure are governed by a poro-elastoplastic interface law incorporating slip-weakening friction, dilatancy, and tensile strength degradation. Block preconditioning of the coupled tangent system ensures robustness across a wide range of fracture behaviors, including friction and tensile hydraulic failure. Solver accuracy is verified – for the first time – against a comprehensive suite of semi-analytical rupture propagation solutions of increasing complexity: fluid-driven frictional ruptures, dilatant ruptures with permeability changes, and penny-shaped hydraulic fractures spanning the viscosity-to-toughness transition. Two multi-fracture examples further demonstrate the solver’s capabilities: injection into intersecting fractures, and a hydraulic fracture intersecting a strike-slip fault. These highlight the ability of the algorithm to capture frictional slip, dilatancy, permeability evolution, and tensile opening within a unified framework, making it well suited for fluid-driven rupture simulation in faulted and fractured rocks.