Water–sand flow triggered by rainfall is the dominant mechanism for instability and failure of sand slopes. To further analyze the stability state of sand on a slope under different rainfall conditions, the initiation conditions and flow characteristics of water–sand flows are studied. Based on the theory of equilibrium forces and hydrological dynamics, a 1:100-scale analog model is built and verified with field observation data. The results indicate three dynamic stabilization stages of the sand slope under different weather conditions: dry sand, wet sand, and water–sand flow. Water–sand flows are triggered easily under short duration and heavy rainfall conditions. The rainfall threshold required to initiate water–sand flow is 4.14 mm/h. Rainfall amount and duration required to initiate water–sand flow decrease with fine sand content increasing. A sand head that develops at the front of the water–sand flow results in a flow along the edge of the sand debris flow and a “tree root” flow morphology. Modeling results are consistent with theoretical analysis and field observations.

中文翻译：

---

不同降水条件下砂质边坡稳定性的模拟模型

降雨触发的水沙流是造成沙质边坡失稳和破坏的主要机制。为了进一步分析边坡在不同降雨条件下的稳定状态，研究了水沙流的起爆条件和流动特性。基于平衡力和水文动力学理论，建立了1：100比例的模拟模型，并通过现场观测数据进行了验证。结果表明，在不同天气条件下，沙坡的三个动态稳定阶段：干沙，湿沙和水沙流。在短持续时间和强降雨条件下，很容易触发水沙流。启动水沙流所需的降雨阈值为4.14 mm / h。随着细砂含量的增加，引发水沙流动所需的降雨量和持续时间会减少。在水沙流前部发育的沙头导致沿着沙屑流边缘的水流和“树根”水流形态。建模结果与理论分析和现场观察一致。