ISSN 1000-3665 CN 11-2202/P

    降雨诱发的浅表堆积层滑坡成因机理与稳定性预测模型

    Mechanism of rainfall-induced shallow landslide and stability prediction model

    • 摘要: 强降雨引起的滑坡多以浅表堆积层滑移为主,易群发、危害性大,其地下水和土体内部含水率对降雨的水文响应机制复杂,难以精准开展稳定性预测。为研究降雨引起的滑坡水文响应对稳定性的影响,以四川省青川县后山里滑坡为例,开展现场降雨入渗监测、相关性分析和力学分析。通过连续3年的降雨量、土体水分和地下水位等监测,分析降雨入渗-土体体积含水率-地下水位的响应规律,得到降雨量与地下水位的相关关系,并基于无限斜坡稳定性计算公式构建基于降雨量和地下水位埋深的浅层滑坡稳定性预测模型。结果表明:(1)年内地下水呈周期性波动,分为缓慢下降期、快速下降期和快速上升期三个阶段,且降雨量与地下水埋深呈线性负相关,与水位升幅相关性不显著;(2)根据稳定性预测模型确定了该滑坡失稳的临界降雨阈值为81.8 mm/d,地下水埋深阈值为0.73 m。研究结果可为降雨诱发浅表堆积层滑坡的预警预报提供参考。

       

      Abstract: The rainfall-induced shallow landslides are primarily debris landslides, which features simultaneity with significant hazard, and the hydrological response mechanism of water table and soil moisture content to precipitation of this type of landslide is sophisticated, which makes it difficult to predict the slope stability accurately. To further study the influence of the rainfall-triggered internal hydrological responses on slope-stability, on-site precipitation infiltration monitoring, correlation analysis and mechanical analysis were carried out on the Houshanli landslide in Qingchuan County, Sichuan Province. The relationship between precipitation and water table was proposed based on climate and hydrological monitoring data obtained within three year interval. The response of rainfall infiltration, soil volumetric water content and water table were analyzed. The results indicate that: (1) groundwater exhibits periodic fluctuations throughout the year, characterized by three phases of slow decline, rapid decline, and rapid ascent; a linear negative correlation between precipitation and water table was found, and no significant correlation was observed with the water table increment; (2) through the infinite slope model and the relationship between precipitation and water table, a prediction model for shallow landslide stability was constructed. The precipitation threshold (81.8 mm/d) and water table threshold (0.73 m) were determined which has good agreement with the actual situations. This provides an early warning method for rainfall-induced shallow landslides by monitoring these two factors.

       

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