SPH numerical modelling of landslide movements as coupled two-phase flows with a new solution for the interaction term

Abstract

In this paper, the theoretical framework is a depth-integrated two-phase model capable of considering many essential physical aspects such as reproducing the propagation of debris flows with soil permeability ranging from high to low and considering the pore-water pressure evolution. In this model, the pore fluid is described by an additional set of depth-integrated balance equations in order to take into account the velocity of pore fluid. The model employs a frictional rheological law for the granular material, and the interstitial fluid is treated as a Newtonian fluid. A drag law describes the interaction between interstitial fluid and grains. The variables of permeability, porosity, and drag force are included in the governing equations to consider the interaction between the phases. This paper aims to extend a generalized two-phase depth-integrated model to enhance the description of the interaction between the two phases and their respective movements. It allows us to increase our understanding of the mechanism behind natural rapid landslides. To evaluate the developed approach, a set of dam-break problems has been performed. These simulations provide interesting information in simple and controlled situations on the landslide propagations with different degrees of soil permeability and the interaction between solid and fluid phases. The extended model has also been applied to simulate the dynamics of the Acheron rock avalanche, which is an appropriate benchmark to examine the applicability of the model to real cases.