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Simultaneous analysis of slope instabilities on a catchment-scale using coupled surface and subsurface flows
Engineering Geology ( IF 7.4 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.enggeo.2020.105750
Yulong Zhu , Tatsuya Ishikawa , Srikrishnan Siva Subramanian , Bin Luo

Abstract High-velocity runoff generated in hillslopes during heavy rainfall caused by typhoon increases chances of instability of the embankment slopes at the exit of the gully. Such effects of high-velocity runoff are usually neglected in conventional rainfall-induced slope failure analysis. In order to consider the effects of runoff on the slope instability, this study attempts to simulate the runoff, infiltration, seepage, and slope instabilities on a small catchment-scale simultaneously. For this purpose, this study firstly proposes a coupled model of surface flow, subsurface flow, and soil mechanics based on shallow water equations, Richards's equation, Green-Ampt infiltration capacity model, and local factor of safety (LFS) approach. Next, to make the proposed coupled model effective in the practical analysis of runoff, a diffusion wave approximation of shallow water equations is validated by numerical simulations, and then it is used to replace shallow water equations in the proposed coupled model. Finally, the proposed coupled model is verified by Abdul and Gillham system and applied to a natural slope in Hokkaido, Japan inside a small catchment with an area of 0.4675 km2. The numerical results highlight the influences of runoff from upstream on the embankment slope failure at the exit of the gully. Furthermore, the small catchment-scale slope instabilities assessment approach proposed in this study provides an effective approach for simulating heavy rainfall induced runoff and slope instabilities. The distribution map of the factor of safety (FOS) has significant implications for precisely determining the dangerous spots (instead of areas) on a small catchment-scale and accurately releasing early warning information to these dangerous spots.

中文翻译:

使用耦合的地表和地下流同时分析流域尺度的边坡不稳定性

摘要 台风强降雨期间山坡产生的高速径流增加了沟渠出口路堤边坡失稳的几率。在传统的降雨引起的边坡破坏分析中,这种高速径流的影响通常被忽略。为了考虑径流对边坡失稳的影响,本研究尝试同时模拟小流域尺度上的径流、入渗、渗流和边坡失稳。为此,本研究首先基于浅水方程、Richards 方程、Green-Ampt 入渗能力模型和局部安全系数(LFS)方法提出了地表流、地下流和土壤力学的耦合模型。接下来,为了使所提出的耦合模型在径流的实际分析中有效,通过数值模拟验证了浅水方程的扩散波近似,然后用它来代替所提出的耦合模型中的浅水方程。最后,提出的耦合模型通过Abdul 和Gillham 系统验证,并应用于日本北海道一个面积为0.4675 平方公里的小流域内的天然斜坡。数值结果突出了上游径流对冲沟出口路堤边坡破坏的影响。此外,本研究提出的小流域边坡不稳定性评估方法为模拟强降雨引起的径流和边坡不稳定性提供了一种有效的方法。
更新日期:2020-09-01
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