A Numerical Simulation Study on the Critical Erosion of Laboratory-Scale Debris Flow

Debris flow erosion is key to the escalation of potential hazards, which may jeopardize the sustainable development of nearby human habitats. However, studies pertaining to this issue are impeded by the intricate interactions of flow and sediment. Thus, this study introduces an unresolved CFD-DEM coupled simulation primarily relying on a classical numerical simulation and a physical experiment to study the critical erosion process of debris flows on a dry basal sediment under laboratory scale. Results indicate that three layers of substrate bed can be verified during the erosion process, and there is a positive correlation between the erosion depth and the particle size with the Froude number of debris flow, as well as between the erosion length and the critical entrainment transport with the total mass of debris flow. In addition, thresholds for the collisional point load and the impact energy of debris flow head, which are essential for predicting the attenuating rates of erosive depth and the critical entrainment transport, have been proposed based on data regressions derived from power functions. The coupled numerical approach is capable of accurately simulating the erosion behavior of debris flows similarly to physical model experiments, thereby providing both theoretical and practical insights into the dynamics of erosion.