缓倾黄土滑坡稳定性分析及阈值研究——以廖集村滑坡为例
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摘要
以天水廖集村缓倾黄土滑坡为例,通过多种试验手段获取滑坡特征参数,建立非饱和入渗与稳定性分析的滑坡耦合模型,基于降雨入渗过程和斜坡失稳机制分析,着重在初始条件变化下,求得相应状态下考虑降雨过程的雨强-历时滑坡阈值.数值模拟结果表明:干燥状态下,土体下渗困难,仅对表层含水率影响明显,而湿润状态下,下渗迅速,基质吸力显著降低,在更短的时间滑坡即会失稳.故湿润状态下,降雨强度-历时滑坡阈值的判据标准低于干燥状态,降雨持时<150 h且雨强>1.2mm/h的组合区间即会发生滑坡,多为强降雨天气.干燥状态时,降雨持时>200 h,雨强为0.41～2.08mm/h为滑坡发生的优势组合区间,往往为连阴雨天气.
A study was made of an inclined loess landslide at Liaoji Village in Tianshui City. An unsaturated seepage and stability analysis numerical model was built, based on features of landslide obtained from field tests; to analyze the process of rainfall infiltration and instability mechanism, the warning criterion of typical initial state was established. As was shown in the numerical model, when in dry condition, water was difficult to infiltrate to the deep when moisture content was only in the surface. But in wet conditions, the seepage was rapid and unhindered, and the distribution of matric suction decreased obviously.As a result the slope would fail in a shorter time. The rainfall intensity-duration thresholds in corresponding initial state were proposed. The intensity-duration(I-D) threshold was lower in wet condition than that in dry condition, and duration <150 h rainfall intensity>1.2 mm/h would induce a landslide in a torrential rain. The duration >200 h and rainfall intensity ranging from 0.41-2.08 mm/h was a primary combination of I-D threshold in dry condition, being present in a continuous rain.
A study was made of an inclined loess landslide at Liaoji Village in Tianshui City. An unsaturated seepage and stability analysis numerical model was built, based on features of landslide obtained from field tests; to analyze the process of rainfall infiltration and instability mechanism, the warning criterion of typical initial state was established. As was shown in the numerical model, when in dry condition, water was difficult to infiltrate to the deep when moisture content was only in the surface. But in wet conditions, the seepage was rapid and unhindered, and the distribution of matric suction decreased obviously.As a result the slope would fail in a shorter time. The rainfall intensity-duration thresholds in corresponding initial state were proposed. The intensity-duration(I-D) threshold was lower in wet condition than that in dry condition, and duration <150 h rainfall intensity>1.2 mm/h would induce a landslide in a torrential rain. The duration >200 h and rainfall intensity ranging from 0.41-2.08 mm/h was a primary combination of I-D threshold in dry condition, being present in a continuous rain.
引文
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[13] Rahardjo H, Li X W, Toll D G, et al. The effect of antecedent rainfall on slope stability[J]. Geotechnical&Geological Engineering, 2001, 19(3/4):371-399.
[14] Huang A B, Lee J T, Ho Y T, et al. Stability monitoring of rainfall-induced deep landslides through pore pressure profile measurements[J]. Soils&Foundations,2012, 52(4):737-747.
[15]杨仲康,陈冠,孟兴民,等.基于现场渗透试验的黄土滑坡体入渗特性[J].兰州大学学报:自然科学版,2017, 53(3):285-291.
[16]加拿大GEO-SLOPE国际有限公司.非饱和土体渗流分析软件SEEP/W用户指南[M].中仿科技公司译.北京:冶金工业出版社, 2011:25-30.
[17] Mcbride D, Cross M, Croft N, et al. Computational modelling of variably saturated flow in porous media with complex three-dimensional geometries[J]. International Journal for Numerical Methods in Fluids, 2006, 50(9):1085-1117.
[18] Tsai T L, Chiang S J. Modeling of layered infinite slope failure triggered by rainfall[J]. Environmental Earth Sciences, 2013, 68(5):1429-1434.
[19]李萍,李同录,王红,等.非饱和黄土土-水特征曲线与渗透系数Childs&Collis-Geroge模型预测[J].岩土力学, 2013, 38(增刊2):184-189.
[20] Chiang S H, Chang K T. Application of radar data to modeling rainfall-induced landslides[J]. Geomorphology, 2009, 103(3):299-309.
[21] Bumb A C, Mckee C R, Evans R B, et al. Design of lysimeter leak detector networks for surface impoundments and landfills[J]. Groundwater Monitoring&Remediation, 2010, 8(2):102-114.
[22]曾润强,王思源,曾宇桐,等.兰州市皋兰山铁三小滑坡形成条件及其稳定性分析[J].兰州大学学报:自然科学版, 2015, 51(3):339-343.
[23]刘艳辉,刘丽楠.基于诱发机理的降雨型滑坡预警研究:以花岗岩风化壳二元结构斜坡为例[J].工程地质学报, 2016, 24(4):542-549.
[24] Chen C Y, Chen T C, Yu F C, et al. Rainfall duration and debris-flow initiated studies for real-time monitoring[J]. Environmental Geology, 2005, 47(5):715-724.
[2] Huggel C, Khabarov N, Obersteiner M, et al. Implementation and integrated numerical modeling of a landslide early warning system:a pilot study in Colombia[J]. Natural Hazards, 2010, 52(2):501-518.
[3] Cardinali M, Galli M, Guzzetti F, et al. Rainfall induced landslides in December 2004 in south-western Umbria,central Italy:types, extent, damage and risk assessment[J]. Natural Hazards&Earth System Sciences,2006, 6(2):237-260.
[4] Pasuto A, Silvano S. Rainfall as a trigger of shallow mass movements:a case study in the Dolomites, Italy[J]. Environmental Geology, 1998, 35(2/3):184-189.
[5] Ayalew L. The effect of seasonal rainfall on landslides in the highlands of Ethiopia[J]. Bulletin of Engineering Geology&the Environment, 1999, 58(1):9-19.
[6] Cannon S H, Gartner J E, Wilson R C, et al. Storm rainfall conditions for floods and debris flows from recently burned areas in southwestern Colorado and southern California[J]. Geomorphology, 2008, 96(3):250-269.
[7] Guzzetti F, Peruccacci S, Rossi M, et al. The rainfall intensity-duration control of shallow landslides and debris flows:an update[J]. Landslides, 2008, 5(1):3-17.
[8] Kwantun L, Juiyi H. Prediction of landslide occurrence based on slope-instability analysis and hydrological model simulation[J]. Journal of Hydrology, 2009, 375(3):489-497.
[9]亓星,许强,孙亮,等.降雨型黄土滑坡预警研究现状综述[J].地质科技情报, 2014, 13(6):219-225.
[10] Dahal R K, Hasegawa S. Representative rainfall thresholds for landslides in the Nepal Himalaya[J]. Geomorphology, 2008, 100(3/4):429-443.
[11]唐栋,李典庆,周创兵,等.考虑前期降雨过程的边坡稳定性分析[J].岩土力学, 2013, 42(11):3239-3248.
[12] Ponziani F, Pandolfo C, Stelluti M, et al. Assessment of rainfall thresholds and soil moisture modeling for operational hydrogeological risk prevention in the Umbria region(central Italy)[J]. Landslides, 2012, 9(2):229-237.
[13] Rahardjo H, Li X W, Toll D G, et al. The effect of antecedent rainfall on slope stability[J]. Geotechnical&Geological Engineering, 2001, 19(3/4):371-399.
[14] Huang A B, Lee J T, Ho Y T, et al. Stability monitoring of rainfall-induced deep landslides through pore pressure profile measurements[J]. Soils&Foundations,2012, 52(4):737-747.
[15]杨仲康,陈冠,孟兴民,等.基于现场渗透试验的黄土滑坡体入渗特性[J].兰州大学学报:自然科学版,2017, 53(3):285-291.
[16]加拿大GEO-SLOPE国际有限公司.非饱和土体渗流分析软件SEEP/W用户指南[M].中仿科技公司译.北京:冶金工业出版社, 2011:25-30.
[17] Mcbride D, Cross M, Croft N, et al. Computational modelling of variably saturated flow in porous media with complex three-dimensional geometries[J]. International Journal for Numerical Methods in Fluids, 2006, 50(9):1085-1117.
[18] Tsai T L, Chiang S J. Modeling of layered infinite slope failure triggered by rainfall[J]. Environmental Earth Sciences, 2013, 68(5):1429-1434.
[19]李萍,李同录,王红,等.非饱和黄土土-水特征曲线与渗透系数Childs&Collis-Geroge模型预测[J].岩土力学, 2013, 38(增刊2):184-189.
[20] Chiang S H, Chang K T. Application of radar data to modeling rainfall-induced landslides[J]. Geomorphology, 2009, 103(3):299-309.
[21] Bumb A C, Mckee C R, Evans R B, et al. Design of lysimeter leak detector networks for surface impoundments and landfills[J]. Groundwater Monitoring&Remediation, 2010, 8(2):102-114.
[22]曾润强,王思源,曾宇桐,等.兰州市皋兰山铁三小滑坡形成条件及其稳定性分析[J].兰州大学学报:自然科学版, 2015, 51(3):339-343.
[23]刘艳辉,刘丽楠.基于诱发机理的降雨型滑坡预警研究:以花岗岩风化壳二元结构斜坡为例[J].工程地质学报, 2016, 24(4):542-549.
[24] Chen C Y, Chen T C, Yu F C, et al. Rainfall duration and debris-flow initiated studies for real-time monitoring[J]. Environmental Geology, 2005, 47(5):715-724.
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