Simulation of the erosion process of landslide dams due to overtopping considering variations in soil erodibility along depth
Simulation of the erosion process of landslide dams due to overtopping considering variations in soil erodibility along depth
复制标题
DOI：
10.5194/nhess-10-933-2010
复制
发表时间：
2010-01-01
影响因子：
4.6
通讯作者：
Zhang, L. M.
中科院分区：
文献类型：
--
作者：
Chang, D. S.;Zhang, L. M.
滑坡坝通常由新沉积的非均质、未固结或固结不良的土料组成，易发生漫顶破坏。提出了一种基于物理的溃坝模型来模拟此类滑坡坝的溃坝过程。该模型可以预测溃口演变、冲刷速率和出流过程线。一个电子表格的开发，以数字实现模型。利用该模型对2008年汶川地震后唐家山滑坡坝和小岗尖滑坡坝的侵蚀过程进行了分析。滑坡坝的可蚀性沿深度沿着变化较大。预测的关键破坏参数（即，考虑土壤可蚀性沿着深度变化的最终溃口尺寸、破坏时间和峰值流出率）与观测值吻合良好。进一步的敏感性分析表明，土壤可蚀性对滑坡坝的溃决过程有显著影响。土壤可蚀性越高，溃口越大，溃口破坏时间越短，最大出流率越大。随着滑坡堆积物抗蚀能力的增强，溃口河道沿深度方向的侵蚀速率减小。在这两个案例研究中，如果假定土壤可蚀性参数沿沿着深度恒定，则无法正确预测关键的破坏参数。
A landslide dam typically comprises freshly deposited heterogeneous, unconsolidated or poorly consolidated earth materials and is vulnerable to overtopping breaching. A physically-based breach model is presented to simulate the breaching process of such landslide dams. The new model can predict the breach evolution, the erosion rate, and the outflow hydrograph. A spreadsheet is developed to numerically implement the model. The erosion processes of Tangjiashan Landslide Dam and Xiaogangjian Landslide Dam induced by the 2008 Wenchuan earthquake are analyzed using the new model. The erodibility of the two landslide dams varies significantly along depth. The predicted key breaching parameters (i.e., final breach size, failure time, and peak outflow rate) considering the variations in the soil erodibility along depth agree well with the observed values. Further sensitivity analysis indicates that the soil erodibility affects the breaching process of a landslide dam significantly. Higher soil erodibility will lead to a larger breach, a shorter failure time and a larger peak outflow rate. The erosion rate of the breach channel in the depth direction decreases with increasing erosion resistance of the landslide deposits. In the two case studies, the key breaching parameters cannot be properly predicted if constant soil erodibility parameters along depth are assumed.