Lateral slope deposit failure represents a major source of material for debris flow/flood formation in headwater regions. From the perspective of inducing factors, such failures are the result of combined action of hydrodynamic and gravitational forces. This work investigated the failure process of a lateral slope soil deposit using indoor flume experiments. The key factors considered were the fine particle content and bulk density of the soil deposit, inflow discharge, and channel slope. Overall, the failure process can be divided into three stages: slope toe erosion stage, frequent failure stage, and gradual stabilization stage. Results revealed that greater bulk density and more fine particle content decreased entrainment and that slope angle has a positive effect on entrainment of the soil body. Debris floods, which occurred only when the fine particle content of the soil deposit was < 30% and only when the channel slope was > 7°, formed more easily when the bulk density of the deposit was < 1.5 or > 1.8 g/cm³. Following analysis of the factors influencing soil body entrainment, an experimental-based critical runoff condition was proposed for debris flood formation. The findings of this study enhance understanding of the mechanism of debris flood formation, which could help improve debris flood forecasting in headwater regions of mountainous catchments.

侧坡沉积破坏是源头地区泥石流/洪水形成的主要材料来源。从诱发因素来看，此类故障是水动力和重力共同作用的结果。这项工作通过室内水槽实验研究了侧坡土沉积物的破坏过程。考虑的关键因素是土壤沉积物的细颗粒含量和容重、流入流量和渠道坡度。总的来说，破坏过程可分为三个阶段：坡脚侵蚀阶段、频繁破坏阶段和逐渐稳定阶段。结果表明，容重越大、细颗粒含量越高，夹带量越小，坡度角对土体的夹带有正向影响。碎片泛滥，³ . 在分析影响土体夹带的因素后，提出了基于实验的泥石流形成临界径流条件。本研究的结果加深​​了对泥石流形成机制的理解，有助于提高山区流域源头地区泥石流的预报。