A study of overtopping breach process with soil–water erosion using improved smoothed particle hydrodynamics

The overtopping breach of embankment is a kind of serious geological disaster which involves complex soil–water coupling and interaction mechanisms. To investigate the coupling mechanical behavior in the overtopping breach processes of embankments, a unified updated Lagrangian form of governing equation system based on improved smoothed particle hydrodynamics (SPH) is proposed. In the present work considering soil–water interaction, the embankment soil is described using an erosive soil model with strength reduction to describe the fine particle migration. A simple inflow boundary is constructed based on the equation of water balance to improve the numerical efficiency. After validation of the proposed model and approach with experiment, two-dimensional as well as three-dimensional cases with different soil cohesion are investigated, in which the evolution of the soil–water profile is tracked. In the case of three-dimensional model, four typical failure modes of the overtopping breach process of embankment are reconstructed. Results show that the increase in soil cohesion can induce a steep downstream slope during overtopping breach, which is related to the representative phenomenon called “headcut” erosion.