基于RAMMS-AVALANCHE模型的雪崩模拟参数敏感性分析

Sensitivity Analysis of Avalanche Simulation Parameters Based on RAMMS-AVALANCHE Model

以巩乃斯大陆性气候雪崩危险区为研究背景,建立三维数字地形模型对雪崩运动过程进行模拟。研究RAMMS雪崩数值模拟结果的影响因素,分析计算网格分辨率、雪层断裂深度、摩擦系数3种参数值对模拟结果的影响程度及敏感性。通过单因素分析法对比不同参数下模拟结果进而得出3种参数的影响程度,采用灰色关联法分析参数对模拟结果的敏感性。结果表明:选择合适的计算网格分辨率能提高模拟结果的准确性;雪层断裂深度每减少10%,流动高度变化率在5%~7%;流动速度变化率在1%~2%;冲击力变化率在2%~3%;而摩擦系数的大小主要对堆积区特征值和雪崩停止时间产生较大影响,对运动过程中的特征值影响较小。在此基础上进行敏感度计算,根据计算结果确定各特征值最大影响性时参数的主次关系。研究结果明晰了雪崩模拟各输入参数的敏感性,可有效提高雪崩数值模拟参数选取的合理性和计算结果的准确性,为雪崩灾害危险程度分析提供依据。

A three-dimensional digital terrain model was built to simulate the avalanche movement process in the avalanche danger zone of the Gongnaisi continental climate as the research background.To study the influencing factors of the numerical simulation results of RAMMS avalanches,and to analyze the influence and sensitivity of the three-parameter values of computational grid resolution,snow fracture depth,and friction coefficient on the simulation results.The influence degree of the three parameters was obtained by comparing the simulation results under different parameters through the single factor analysis method,and the sensitivity of the parameters to the simulation results was analyzed by the grey correlation method.The results show that choosing an appropriate computational grid resolution improves the accuracy of the simulation results;the rate of change of flow height is in the range of 5%to 7%for every 10%reduction in the depth of snow fracture.The rate of change of flow velocity is in the range of 1%to 2%.The rate of change of impact force is in the range of 2%to 3%,and the magnitude of friction coefficient mainly has a large impact on the eigenvalues of the accumulation zone and the avalanche stopping time,and has a smaller impact on the eigenvalues of the kinematic process.On this basis,sensitivity calculations were carried out,based on the calculations results to determine the parameters primary and secondary relationships at the time of the maximum influence of each eigenvalue.The research results clarify the sensitivity of the input parameters of avalanche simulation,which can effectively improve the rationality of the selection of parameters and the accuracy of the calculation results of avalanche numerical simulation,and provide a basis for the analysis of avalanche disaster risk level.