Numerical investigations on evolution mechanism of contact erosion in layered soils considering particle-scale parameters

Abstract

Internal erosion is one of the leading causes of failures in transportation infrastructures including bridges and road embankments. For layered subsoil conditions, contact erosion may occur if the gradation of soil in different layers is not properly selected, and is controlled by the speed of inflowing water and the particle sizes. This phenomenon is difficult to observe on-site or in the laboratory and the underlying mechanism still needs to be clarified as it occurs inside the subsoil layer. This paper presents a particle-scale study that utilizes physical tests and representative volume CFD-DEM simulations to explore the contact erosion process at the interface between soil layers consisting of coarse-grained and fine-grained particles. It is first calibrated and validated by comparing the simulation results with experimental observations. Then the influences of contributing factors on contact erosion initiation and progression from the view of particle scales are analyzed. The results show that particle size ratio is a significant factor that determines the occurrence and development of contact erosion. The specific gravity of particles affects their erosion resistance, while the effect of particle friction is not obvious since the transport of fine non-cohesive particles does not involve significant particle sliding. Particle shape has a major influence on the contact erosion process. Meanwhile, the critical inflow velocity and particle size ratio for contact erosion occurrence can be determined via the coupled model presented in this study.