降雨型浅层滑坡潜在重力侵蚀量模拟与计算  

Simulation and prediction of the potential gravity erosion during rainfall

作　　者：李通 王云琦[1,2] 祁子寒 李耀明[1,2] 何相昌 骆丕昭 LI Tong;WANG Yunqi;QI Zihan;LI Yaoming;HE Xiangchang;LUO Pizhao(Three-Gorges Reservoir Area(Chongqing)Forest Ecosystem Research Station,Ministry of Education,School of Soil and Water Conservation,Beijing Forestry University,100083,Beijing,China;Three-Gorges Reservoir Area(Chongqing)Forest Ecosystem Research Station,School of Soil and Water Conservation,Beijing Forestry University,100083,Beijing,China)

机构地区：[1]北京林业大学水土保持学院重庆三峡库区森林生态系统教育部野外科学观测研究站,北京100083 [2]北京林业大学水土保持学院重庆缙云山三峡库区森林生态系统国家定位观测研究站,北京100083

出　　处：《中国水土保持科学》2024年第5期41-52,共12页Science of Soil and Water Conservation

基　　金：国家自然科学基金“降雨条件下植物根系动态固土护坡效应研究”(31971726);北京林业大学热点追踪项目“重庆缙云山森林火灾调查和灾后植被恢复重建研究”(2022BLRD11)。

摘　　要：传统的边坡稳定模型以边坡安全评估为主,以降雨型滑坡为主的潜在重力侵蚀量模拟和预测为当前水土保持领域研究中亟待完善的工作,当前暂无系统的模型和计算流程可供参考。为实现降雨滑坡潜在重力侵蚀量的预测和量化,采用COMSOL Multiphysics在流固耦合框架下自定义局部稳定系数标量场LFS,模拟暴雨条件下坡体滑床3D轮廓发展过程及潜在侵蚀量动态,并与传统强度折减法进行了对比。结果表明:暴雨过程中暂态饱和达到一定深度后坡面出现潜在重力侵蚀,随着降雨影响深度的增大,潜在侵蚀量持续增大,形成由浅渐深的潜在滑床,最大侵蚀深度位于坡脚;LFS法可实现与强度折减法较为吻合的滑床轮廓,且较强度折减法计算效率更高,结果更保守,可获得准确的临界失效范围;降雨型浅层滑坡潜在重力侵蚀量模拟流程为:1)实地地形、土壤、水文勘察,2)渗流-应力耦合模型构建,3)LFS等值面提取,4)几何体切割和体积积分。[Background]Rainfall induced landslide is a common kind of mountain hazard in China,and its mass in near failure state makes it more susceptible to further erosion and may become the main source of debris flow.The traditional slope stability analysis models mainly focus on slope safety assessment,but they are not up to the calculation of the Potential Gravity Erosion(PGE)induced by rainfall triggered landslide.For the absence of such methods,simulation and prediction of PGE is still an urgent work in Soil and Water Conservation.[Methods]An idealized 3D slope model was built in COMSOL to quantify the PGE.The transient pore water pressure and solid deformation development of slope soil under rainfall scenario were simulated in the fluid-solid coupling framework.Furtherly,both the global and local stability of slope were analyzed by using the strength reduction method(SRD)and defining a Local Factor of Safety(LFS)scalar field,and the volume integration of PGE amount quantified based on the LFS.Finally,the practicability of this work was evaluated and confirmed by comparing its slide surface geometries with SRD.[Results]1)The pore water pressure(PWP)was linearly distributed with the elevation from+100 kPa to-100 kPa in initial state,and decreased significantly with rainfall at surface layer.After 5 d of rainfall,the infiltration depth was about 3.5 m with a transient saturation depth in 2 m.The effective stress increased with depth and parallel distributed to the slope surface in the initial state,and decreased significantly in surface layer and increased slightly in the deep layer during rainfall.The range of average effective stress in 5 d of rainfall changed from 204-16.9 kPa to 206-1.86 kPa.2)In the early stage of rainfall,the LFS of slope was generally greater than 1,and then gradually decreased on the slope surface with a trend spreading from shallow to deep layer.The shallow straight failure surface(depth<1 m)appeared in 2 d and subsequently evolved into a deep arc-shaped sliding surface.The simulated data of

关 键 词：降雨入渗 流固耦合 数值模拟 边坡稳定 潜在重力侵蚀 

分 类 号：S157[农业科学—土壤学]