考虑基层裹挟的碎屑流铲刮效应数值模拟

Numerical simulation of entrainment effect of debris flow considering entraining substrate material

基于碎屑流铲刮基层的作用机理,引入浓度悬浮模型用于描述混合区土体动力特性,采用考虑基层裹挟的Herschel-Bulkley-Papanastasiou(HBP)模型描述高速运移的碎屑流与基层材料裹挟掺混的动力过程,并采用光滑粒子流体动力学(SPH)方法求解.选择典型小比尺室内模型试验验证该方法的有效性,计算所得滑体最终堆积形态和碎屑流影响范围与试验结果一致.在此基础上开展基层材料物理力学参数的敏感性分析,结果表明,在一定范围内基层厚度增加将导致侵蚀深度增大并收敛于某极限值.基层材料的内摩擦角、黏聚力和动力黏度的增加均会减少碎屑流对基层的铲刮效应和基层隆起范围,但内摩擦角和动力黏度的增加对基层隆起范围影响较小.在合理土体物理参数范围内,仅黏聚力的增加即能显著抑制以上2种现象.

A concentration suspension model was introduced to describe the dynamic characteristics of soil in mixed zone based on the theory of debris flow entrainment effect,and then the Herschel-Bulkley-Papanastasiou(HBP)model considering the entrainment of substrate material was utilized to describe the high-speed dynamic process of the mixture of debris flow and substrate material.The smoothed particle hydrodynamics(SPH)method was used to solve the boundary value problems.A typical small scale model experiment was selected to verify the effectiveness of this method.The final accumulation shape and the influenced range of debris flow obtained by the proposed method were consistent with the experiment results.On this basis,a sensitivity analysis of parameters was carried out.Results show that as the increase of the thickness of substrate material in a certain range,the erosion depth will increase and converge to a certain limit value.The increase of internal friction angle,cohesion and dynamic viscosity of substrate material will reduce the entrainment of substrate material and the uplift range of substrate.However,the increase of internal friction angle and dynamic viscosity has little effect on the uplift range of substrate.The increase of cohesion can significantly inhibit the above two phenomena within the reasonable range of soil physical parameters.