Response of a loess landslide to rainfall: observations from a field artificial rainfall experiment in Bailong River Basin, China
Response of a loess landslide to rainfall: observations from a field artificial rainfall experiment in Bailong River Basin, China
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DOI：
10.1007/s10346-017-0924-6
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发表时间：
2018-05
期刊：
影响因子：
6.7
通讯作者：
Guan Chen;Xing-min Meng;Liang Qiao;Yi Zhang;Siyuan Wang
中科院分区：
文献类型：
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作者：
Guan Chen;Xing-min Meng;Liang Qiao;Yi Zhang;Siyuan Wang
降雨引起的山体滑坡是中国西北许多黄土覆盖地区的重大灾害。为了研究黄土滑坡对降雨的响应，在甘肃省南部白龙河流域的天然黄土边坡上进行了一系列人工降雨实验。斜坡上安装了仪器来测量地表径流、孔隙水压力、土壤含水量、土压力、位移和降雨量。水文响应也通过延时电阻率断层扫描来表征。结果表明，大部分降雨渗入黄土滑坡，孔隙水压力和含水量对模拟降雨事件响应迅速。这表明黄土滑坡的降雨入渗受到裂隙和大孔隙优先流的显着影响。孔隙水压力和含水量变化的不同模式是由先前的土壤湿度条件以及相应部分的补水和排水之间的平衡决定的。我们观察到人工降雨期间黄土滑坡内孔隙水压力和位移变化的三个阶段：孔隙水压力增加引发斜坡运动，运动加速导致孔隙水压力迅速下降，最后达到稳定状态。我们推断，当斜坡运动加速时，负孔隙水压力反馈过程可能是响应于剪切引起的材料膨胀而发生的。剪胀强化过程可以解释黄土滑坡的半连续运动现象。由长时间间歇性或连续降雨引起的剪胀加固可能会发生，但不会引发斜坡快速破坏。
Rainfall-induced landslides are a significant hazard in many areas of loess-covered terrain in Northwest China. To investigate the response of a loess landslide to rainfall, a series of artificial rainfall experiments were conducted on a natural loess slope, located in the Bailong River Basin, in southern Gansu Province. The slope was instrumented to measure surface runoff, pore water pressure, soil water content, earth pressure, displacement, and rainfall. The hydrological response was also characterized by time-lapse electrical resistivity tomography. The results show that most of the rainfall infiltrated into the loess landslide, and that the pore water pressure and water content responded rapidly to simulated rainfall events. This indicates that rainfall infiltration on the loess landslide was significantly affected by preferential flow through fissures and macropores. Different patterns of pore water pressure and water content variations were determined by the antecedent soil moisture conditions, and by the balance between water recharge and drainage in the corresponding sections. We observed three stages of changing pore water pressure and displacement within the loess landslide during the artificial rainfall events: Increases in pore water pressure initiated movement on the slope, acceleration in movement resulting in a rapid decrease in pore water pressure, and attainment of a steady state. We infer that a negative pore water pressure feedback process may have occurred in response to shear-induced dilation of material as the slope movement accelerated. The process of shear dilatant strengthening may explain the phenomenon of semi-continuous movement of the loess landslide. Shear dilatant strengthening, caused by intermittent or continuous rainfall over long periods, can occur without triggering rapid slope failure.