Numerical modeling of bed deposition in rapid flow-like landslides: a case study of the Gaolou landslide in Shaanxi Province, China

Abstract

Some flow-like landslides tend to lose materials while moving on a relatively dry sliding surface. This phenomenon is called bed deposition. In contrast to the bed entrainment phenomenon, bed deposition is relatively poorly understood. Therefore, an improved depth-averaged model is proposed to quantify this phenomenon. The deposition depth is calculated according to the momentum conservation of the deposited mass, and the rheological property of the sliding mass on the bottom is modified considering an abrupt increase in the depth of the sliding surface after deposition. Utilizing the proposed model, the Gaolou landslide, a typical flowlike landside occurring on October 6th, 2006 with an obvious bed deposition phenomenon in Shaanxi Province of China, is simulated to investigate the influence of bed deposition on its propagation process. The results indicate that the proposed model can effectively depict the bed deposition phenomenon in the Gaolou landslide. Bed deposition dissipates part of the kinetic energy of this landslide; thus, the simulated debris inundation area would likely be overestimated when this effect is neglected. On the other hand, the thin liquefied layer formed by the bed deposition process reduces the friction energy dissipation, contributing to the high mobility of this landslide.