A finite volume method for two-phase debris flow simulation that accounts for the pore-fluid pressure evolution

The temporal and spatial evolution of pore-fluid pressure exerts strong control on debris flow motion because it can counteract normal stresses at grain contacts, reduce friction, and enhance bulk flow mobility. In Iverson’s two-phase debris flow model, the depth-averaged pore pressure equation, which takes into account the effect of shear-induced dilatancy, was combined with a previous model to describe the simultaneous evolution of flow velocity and depth, solid mass, and pore-fluid pressure. In this work, a high-resolution scheme based on the finite volume method was used to solve the system of equations. Several numerical tests were performed to verify the ability of the presented model and the accuracy of the proposed numerical method. Numerical results were compared with experimental data obtained in a laboratory, and the effectiveness of the proposed numerical method for solving practical problems has been proven. Numerical results indicated that increases of the pore-fluid pressure could enhance the motion of debris flow and expand the spread area. Furthermore, results showed that the debris shear-induced dilatancy could affect the evolution of pore-fluid pressure, thus further influencing the motion of debris flow.