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    滑坡扰动对黄土高原山坡水文响应及坡体稳定性的影响

    Impacts of Landslide Disturbance on the Hydrological Responses and Slope Stability in the Loess Plateau

    • 摘要: 降雨型浅层滑坡在重塑山坡地形的同时可能影响下垫面的物理性质和水分运动特征.然而,前序滑坡扰动引起的土壤饱和导水率(Ksat)变化对后续坡体失稳易发性的影响机制仍缺乏深入研究.选取黄土高原典型坡面,耦合基于物理过程的分布式水文模型InHM与无限边坡稳定模型ISA,探讨3种扰动模式(坡顶滑塌(LS1)、整体滑移(LS2)和坡脚崩塌(LS3))造成的Ksat空间异质性如何影响山坡水文响应过程和坡体稳定性.研究结果表明:(1)滑坡扰动引起的土壤Ksat空间异质性显著改变山坡产汇流过程,产流时间平均提前25%~46%,峰值下降20%~30%;(2)滑坡扰动影响坡体内部的水分存蓄能力和分布特征,入渗深度在剥离区平均减小0.20m,而在堆积区平均加深0.10m;(3)滑坡扰动造成的入渗增强、浅层滞水以及孔隙水压力激增等水文过程变化导致坡体自重增大、排水不畅和抗滑力削弱,诱发二次滑坡;(4)3种滑坡扰动模式下坡体失稳风险均加剧,特别是剥离区.此外,失稳的深度和规模在不同植被覆盖条件下存在差异.研究结果从Ksat异质性角度解释了滑坡路径依赖现象,可为黄土高原地区滑坡灾害防治提供理论支撑.

       

      Abstract: Rainfall-triggered shallow landslides reshape hillslope topography and alter the physical properties of the underlying surface as well as the characteristics of soil water movement.However,the impacts of changes in soil saturated hydraulic conductivity (Ksat) caused by the pre-sequence landslide disturbance on the subsequent slope instability susceptibility remain unclear.To elucidate how the spatial heterogeneity of Ksat caused by three landslide-disturbance modes (i.e.,slope top collapse (LS1),overall slip (LS2) and slope toe collapse (LS3)) affects the hydrological response process and slope stability,based on the sampling data and field investigation,physics-based numerical simulations were conducted in a typical hillslope of the Chinese Loess Plateau by coupling the distributed hydrological model (InHM) and the infinite slope model (ISA).The results show that:(1)The spatial heterogeneity of soil Ksat caused by landslide disturbance significantly changed the runoff generation and confluence processes on the hillslope.The runoff initiation time was averagely advanced by 25%~46%,and the peak value decreased by 20%~30%;(2)Landslide disturbance affects the soil water storage capacity and distribution characteristics inside the hillslope.The infiltration depth decreases by 0.20m on average in the stripping area,and deepens by 0.10m on average in the landslide deposit;(3)The changes of hydrological processes such as infiltration enhancement,shallow soil water perching and pore water pressure surge caused by landslide disturbance lead to the increase of slope weight,poor drainage and weakening of anti-sliding force,which induces secondary landslides;(4) The risk of slope instability is aggravated under the three landslide disturbance modes,especially in the stripping area.The depth and scale of potential secondary landslide vary with vegetation coverage conditions.These results help explaining the phenomenon of landslide-path-dependence from the perspective of Ksat heterogeneity,which can provide theoretical surpport for the prevention and control of landslide disasters in the Loess Plateau.

       

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