Spatially distributed landslide triggering analyses accounting for coupled infiltration and volume change
Spatially distributed landslide triggering analyses accounting for coupled infiltration and volume change
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DOI：
10.1007/s10346-020-01451-1
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发表时间：
2020-06
期刊：
影响因子：
6.7
通讯作者：
Zhichen Song;Xiang Li;J. Lizárraga;Lianheng Zhao;G. Buscarnera
中科院分区：
文献类型：
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作者：
Zhichen Song;Xiang Li;J. Lizárraga;Lianheng Zhao;G. Buscarnera
降雨入渗通过孔隙水压力的变化改变非饱和边坡的有效应力，从而引起地面变形。虽然重要的是评估的时间尺度上的安全边际的斜坡下降，这种耦合过程很少考虑在空间分布的危害评估程序的背景下。本文讨论了一种基于物理的、空间分布的、考虑流体力学耦合的模型。该模型依赖于一个矢量化的有限元（FE）求解器来计算变形非饱和无限边坡瞬态流的稳定性。首先，有限元求解器用于研究三种情况下（即，坚硬、膨胀和可塌陷的土壤）。然后，该模型被用于在空间分布计算的上下文中，以评估在一个大区域的安全系数的时空变化。为此，在中国西北部的湿陷性黄土覆盖的山区景观发生的一系列浅层滑坡作为试验场地。分析表明，水力-机械耦合影响模型的性能，计算的破坏时间和不稳定区的面积范围。具体而言，体积崩溃，由于吸力下降，以减少失败的时间相比，刚性土壤的情况下获得的非耦合计算。使用耦合分析的最实质性的优势已被报告与缓坡，其中体积变化驱动的吸力降低率较高是至关重要的捕获滑坡源区，否则会被忽略的非耦合分析。所提出的方法提供了一个完整的滑坡灾害评估工具，因为它结合了水文和力学之间的耦合源，是至关重要的复制滑坡启动的物理。
Rainfall infiltration in unsaturated slopes alters the effective stress through pore water pressure changes, thus causing ground deformation. Although important to assess the timescale over which the margin of safety of a slope decreases, such coupled processes are rarely accounted in the context of spatially distributed hazard assessment procedures. In this paper, a physically based, spatially distributed model accounting for full hydro-mechanical coupling is discussed. The model relies on a vectorized finite element (FE) solver to calculate the stability of deformable unsaturated infinite slopes subjected to transient flow. First, the FE solver is used to study the response of individual slopes to a prolonged rainfall for three scenarios (i.e., rigid, swelling, and collapsible soil). Then, the model is used in the context of spatially distributed computations to assess spatiotemporal variations of factor of safety over a large area. For this purpose, a series of shallow landslides occurred in a mountainous landscape covered by collapsible loess deposits in northwestern China was used as test site. The analyses show that hydro-mechanical couplings affect the performance of the model in terms of computed failure time and areal extent of the unstable zones. Specifically, volume collapse due to suction decrease is found to reduce the time of failure compared with uncoupled computations obtained for a rigid soil scenario. The most substantial advantages of using coupled analyses have been reported with reference to gentle slopes, for which the higher rate of suction reduction driven by volume change was crucial to capture landslide source areas that would otherwise be overlooked by uncoupled analyses. The proposed methodology offers a complete tool for landslide hazard assessment, in that it incorporates sources of coupling between hydrology and mechanics that are crucial to replicate the physics of landslide initiation.