基于不同侵蚀模型的高速崩滑碎屑流动力过程模拟分析

Simulation analysis of dynamic process of debris flow based on different entrainment models

为实现高速崩滑碎屑流沿程侵蚀动力过程的模拟分析,采用连续理论方法对NomashRiver碎屑流动力过程进行了数值模拟。其中,在连续理论模型中采用3种不同侵蚀速率模型,并采用HLLC近似Riemann解对有限体积数值离散控制体单元的界面通量进行了计算求解。致灾范围及运动时间的计算结果均与实际灾害情况吻合良好,验证了计算模拟的正确有效性,并对最终堆积深度、运动速度和侵蚀区域侵蚀深度进行了分析讨论。结果显示:采用McDougall侵蚀模型得到的最终堆积平均深度和最大深度与实测情况较为接近;每个时刻采用Medina侵蚀模型得到的最大速度值最大,其次是采用McDougall侵蚀模型的结果,最后是采用Pitman侵蚀模型的结果;采用McDougall侵蚀模型得到的侵蚀深度分布较为连续,其最大值8.1m与估测值8m比较接近,采用Medina侵蚀模型和Pitman侵蚀模型得到的侵蚀深度结果则较为分散,其最大值分别为10.9m和8.6m。

Numerical simulation of the dynamic process of Nomash River debris flow was carried out using the continuous theory method in this study.Three different entrainment rate models were applied in the continuous theory model,and the HLLC approximate Riemann solution was used to calculate the interface flux of the control unit of the finite volume numerical discrete. Calculation results of disaster scope and motion time were in good agreement with the actual disaster situation,which verified the correctness and validity of the simulation.Then,the final accumulation depth,motion velocity and erosion depth were analyzed and discussed.The results showed that the average depth and maximum depth of final accumulation obtained using McDougall entrainment model were close to those measured.The maximum velocity obtained using the Medina entrainment model at each time was the largest,followed by the result of McDougall entrainment model and the result of Pitman entrainment model.The erosion depth distribution using McDougall erosion model was more continuous,and the maximum value of 8.1 m was close to the estimated value of 8 m.The erosion depth results obtained using Medina erosion model and Pitman erosion model were more dispersed,and their maximum values were 10.9 m and 8.6 m,respectively.