強降雨作用下昔格達邊坡滲流特性及穩定性分析

楊世豪 蘇立君 張崇磊 李丞 胡兵立

摘要：昔格達地層分布于中國西南，其工程性質極差。為分析上覆第四紀殘坡積物的昔格達組粉砂土邊坡在強降雨作用下的滲流特性及穩定性，結合石棉縣莫家崗滑坡，用數值模擬方法研究坡體滲流規律;用MorgensternPrice方法計算各時刻坡體穩定性系數，并分析其變化規律。結果表明：雨水在坡體中逐層入滲，雨停后滲流過程將繼續發展，由于存在土層分界面，坡體滲流特性不同于均質坡體;降雨過程中，孔隙水壓力發生增長的范圍在界面附近加速拓展，雨停后，土層分界面附近第四紀殘坡積物仍處于近飽和狀態;降雨入滲導致坡體邊坡穩定性系數下降，且穩定性系數變化對降雨的響應存在滯后性。

關鍵詞：昔格達組;層狀邊坡;降雨入滲;邊坡穩定

中圖分類號：P642.3 文獻標志碼：A 文章編號：20966717（2020）04001909

收稿日期：20191127

基金項目：國家自然科學基金（41761144077）

作者簡介：楊世豪（1995 ），主要從事地質災害啟動機理研究，Email：347295340@qq.com。

蘇立君（通信作者），男，研究員，博士生導師，Email：sulijun1976@163.com。

Received：20191127

Foundation item：National Natural Science Foundation of China （No. 41761144077）

Author brief：Yang Shihao （1995 ）， main research interest： slope reliability， Email：347295340@qq.com.

Su Lijun （corresponding author）， professor， doctoral supervisor， Email： sulijun1976@163.com.

Analysis of seepage characteristics and stability of Xigeda Formation slope under heavy rainfall

Yang Shihao1，3，Su Lijun1，2，3，Zhang Chonglei1，2，Li Cheng1，3，Hu Bingli1，3

（1.Key Laboratory of Mountain Hazards and Earth Surface Process; Institute of Mountain Hazards and Environment，Chinese Academy of Sciences， Chengdu 610041， P.R. China; 2. Center for Excellence in Tibetan Plateau Earth Sciences， Chinese Academy of Sciences， Beijing 100101， P.R. China; 3. University of Chinese Academy of Sciences， Beijing 100049， P.R. China）

Abstract： Xigeda Formation is distributed in southwest of China， and its engineering properties are very poor. In order to analyze seepage characteristics and stability of silty sand slope of Xigeda Formation overlying Quaternary residual slope sediments under heavy rainfall conditions， seepage law of slope is studied by numerical simulation based on Mojiagang landslide in Shimian County; MorgensternPrice method is used to calculate safety factor of landslide and to analyze their variation laws. The results show that： rainwater infiltrates into slope layer by layer， and seepage process will continue after rainfall. As the existence of soil layer interface， seepage characteristics are different from homogeneous slope; during the rainfall process， the range of pore water pressure growth accelerates near the interface， and the Quaternary residual slope sediments near the interface is still in a nearsaturated state after the rainfall; rainfall infiltration leads to reduction of safety factor of the slope， and stability has a lag in response to rainfall.

Keywords：Xigeda Formation; layered soil slope; rainfall infiltration; slope stability

昔格達地層為廣泛分布于中國西南地區的半成巖河湖相沉積地層，形成于晚更新世與上第三系之間，主要由粉砂土和黏土組成[12]。隨著工程活動在昔格達地層分布區廣泛開展，其工程性質引起學者關注。周平等[3]、王志杰等[4]研究發現，昔格達地層巖土體水穩性差，極易崩解。杜翔宇等[5]研究昔格達地層巖土體的微觀結構特性，并對其強度指標與含水率關系進行闡述。因力學性質特殊，昔格達地層分布區滑坡頻發，相關學者對其進行了研究。……