为揭示土质滑坡中降雨入渗规律和滑坡成因机理,通过对四川南江县100多个滑坡进行现场调查、统计,选取二潢坪滑坡深入剖析典型滑坡成因机理,对降雨量、GPS累积位移、土体孔隙水压力、土体含水率等综合因素分析后,采用有限元数值法对滑坡的降雨入渗过程进行模拟。结果表明:浅层土质滑坡中孔隙水压力及含水率变化有明显滞后现象,降雨初期以垂直坡面入渗为主,一段时间后则以坡向渗流为主;斜坡中前缘孔隙水压力变化比后缘对降雨更敏感,其原因为前缘黏性堆积体、侧壁陡崖及基岩面共同构成斜坡储水边界;因滑体结构的各向异性,降雨过程中土体中局部孔隙水压力及渗流力瞬时剧增,土体饱水使得软黏土层发生软化,最终导致斜坡整体失稳。
Abstract
Through field investigation and statistics of more than 100 landslides in Nanjiang county, the Erhuang ping landslide was selected as a case study to reveal the formation mechanism of and rainfall infiltration in soil landslide. Through analyzing multiple factors including precipitation, accumulative displacement of GPS, pore-water pressure and moisture content of soil, the process of rainfall infiltration of Erhuangping landslide was simulated by finite element analysis. Results showed that the variations of pore-water pressure and soil moisture of shallow soil in the landslide lagged obviously in the initial stage of rainfall precipitation. The main infiltration direction was perpendicular to the surface of slope, and then changed to be along the slope direction. As a water-storing boundary was formed by the cohesive accumulation body, steep side cliff and bedrock surface, pore water pressure in the front edge of slope was more sensitive to rainfall than that in the rear edge does. Due to the anisotropy of slip mass, local pore water pressure and seepage force rises sharply during rainfall, and the soft clay softened, finally resulting in the global instability of slope.
关键词
浅层土质滑坡 /
降雨入渗 /
变形监测 /
成因机理 /
孔隙水压力
Key words
shallow soil landslide /
infiltration of rainfall /
deformation monitoring /
formation mechanism /
pore water pressure
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参考文献
[1] 孔纪名,陈自生.川东“89·7”暴雨过程中的红层滑坡[C]∥滑坡文集(第九集). 北京:中国铁道出版社,1992:36-42.
[2] 范宣梅.平推式滑坡成因机制与防治对策研究[D].成都:成都理工大学,2007.
[3] 殷坤龙,简文星,周春梅,等. 万州区近水平地层滑坡和堆积体成因机制与防治工程研究[R]. 武汉:中国地质大学(武汉),2005.
[4] HUAT B B K,ALI F H J,LOW T H. Water Infiltration Characteristics of Unsaturated Soil Slope and its Effect on Suction and Stability[J]. Geotechnical and Geological Engineering,2006,24(5):1293-1306.
[5] LI Xin-po,WANG Cheng-hua,XU Jun. Surficial Stability Analysis of Unsaturated Loess Slopes Subjected to Rainfall Infiltration Effects[J].Wuhan University Journal of Natural Sciences,2006,11(4): 825-828.
[6] LIU Zi-zhen,YAN Zhi-xin,DUAN Jian, et al. Infiltration Regulation and Stability Analysis of Soil Slope under Sustained and Small Intensity Rainfall[J]. Journal of Central South University,2013,20(9):2519-2527.
[7] RAHARDJO H,LI X W,TOLL D G, et al . The Effect of Antecedent Rainfall on Slope Stability[J]. Geotechnical and Geological Engineering,2001,19(3):371-399.
[8] 袁 东,池永翔,程 刚.闽北地区不同植被类型下滑坡体土层入渗性能研究[J]. 长江科学学院院报,2010,27(5):8-12.
[9] 胡泽铭. 四川红层地区缓倾角滑坡成因机理研究[D].成都:成都理工大学,2013.
[10] 李 江,许 强,胡泽铭,等.红层缓倾角土质滑坡发育环境、分布规律及影响因素研究[J]. 科学技术与工程,2014,14(12):88-93.
[11] 张 群,许 强,易靖松,等. 南江红层地区缓倾角浅层土质滑坡降雨入渗深度与成因机理研究[J]. 岩土工程学报,2016,38(8):1447-1455.
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