基于降雨作用下滑面抗剪强度动态变化的层状边坡稳定性评价
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摘要
降雨入渗对边坡稳定性具有重要影响。鉴于层状边坡在自然情况中广泛存在,因此,开展在降雨情况下的多层状边坡入渗模型及其稳定性研究具有重要意义。考虑各层土体的渗透性能差异,利用约束函数求得各层土体的有效渗透系数,并基于Green-Ampt模型建立层状边坡入渗模型。结合非饱和土强度经验公式,推导了考虑滑面抗剪强度动态变化的层状边坡稳定性方程。最后,对深圳某边坡在不同降雨强度和降雨历时下的稳定性系数进行了计算并对结果进行了分析。结果表明,当湿润锋未达到滑面处时,边坡稳定性系数与降雨历时和降雨强度呈线性关系。考虑边坡入渗能力,提出了降雨入渗临界时间概念。在任意降雨强度下,当降雨历时小于该时间时,边坡均不会失稳。本研究可以用于指导降雨情况下层状边坡的稳定性评价。
Rainfall infiltration has a significant effect on slope stability.It is meaningful to study the infiltration model and stability of layered slopes under rainfall in view of the wide distribution of layered slopes in nature environment.Because of the difference of permeability coefficient of soil layer,the effective permeability coefficient of each layer is obtained via constraint function and the infiltration model of layered slope is derived based on the Green-Ampt model.Based on the empirical formula of unsaturated soil strength,the equations for calculating the stability of layered slopes are proposed with consideration of variation of shear strength of slip surface.Finally,the stability coefficient of a slope in Shenzhen,China under different rainfall intensity and rainfall duration is illustrated and the results are analyzed.The analysis indicates that slope stability coefficient is linearly related to rainfall duration and rainfall intensity before the wetting front reaches the slip surface.Considering the infiltration capacity of soils,the concept of threshold time in rainfall infiltration is introduced.As long as the rainfall duration is shorter than this threshold time,the slope will not lose its stability in rainfall infiltration.The research can be used to guide the stability evaluation of layered slopes under rainfall.
Rainfall infiltration has a significant effect on slope stability.It is meaningful to study the infiltration model and stability of layered slopes under rainfall in view of the wide distribution of layered slopes in nature environment.Because of the difference of permeability coefficient of soil layer,the effective permeability coefficient of each layer is obtained via constraint function and the infiltration model of layered slope is derived based on the Green-Ampt model.Based on the empirical formula of unsaturated soil strength,the equations for calculating the stability of layered slopes are proposed with consideration of variation of shear strength of slip surface.Finally,the stability coefficient of a slope in Shenzhen,China under different rainfall intensity and rainfall duration is illustrated and the results are analyzed.The analysis indicates that slope stability coefficient is linearly related to rainfall duration and rainfall intensity before the wetting front reaches the slip surface.Considering the infiltration capacity of soils,the concept of threshold time in rainfall infiltration is introduced.As long as the rainfall duration is shorter than this threshold time,the slope will not lose its stability in rainfall infiltration.The research can be used to guide the stability evaluation of layered slopes under rainfall.
引文
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[16]林鸿州,李广信,于玉贞,等.基质吸力对非饱和土抗剪强度的影响[J].岩土力学,2007,28(9):1931-1936.
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[19]马雨露,赖成光,习树峰,等.南方高度城市化地区极端降雨特征分析及阈值确定:以深圳市为例[J].水资源与水工程学报,2017,28(2):76-81.
[2]孙金山,陈明,左昌群,等.降雨型浅层滑坡危险性预测模型[J].地质科技情报,2012,31(2):117-121.
[3]谭维佳,王新刚,刘飞.考虑降雨渗流影响的露天煤矿黄土开挖边坡分析[J].地质科技情报,2015,34(1):198-203.
[4]谢守益,徐卫亚.降雨诱发滑坡机制研究[J].武汉水利电力大学学报,1999,32(1):21-23.
[5]张倬元,王士天,王兰生.工程地质分析原理[M].北京:地质出版社,2009.
[6]Gao Y,Yin Y,Li B,et al.Investigation and dynamic analysis of the long runout catastrophic landslide at the Shenzhen landfill on December 20,2015,in Guangdong,China[J].Environmental Earth Sciences,2017,76(1):13.
[7]范宣梅,许强,黄润秋,等.丹巴县城后山滑坡锚固动态优化设计和信息化施工[J].岩石力学与工程学报,2007,26(增刊2):4139-4146.
[8]Green H,Ampt G A.Studies on soil physics:PartⅡ-The permeability of an ideal soil to air and water[J].Journal of Agricultural Science,1912,5(1):1-26.
[9]Chen L,Young M H.Green-Ampt infiltration model for sloping surfaces[J].Water Resources Research,2006,42(7):887-896.
[10]常金源.降雨条件下浅层滑坡稳定性探讨[J].岩土力学,2015,36(4):995-1001.
[11]石振明,沈丹祎,彭铭,等.考虑多层非饱和土降雨入渗的边坡稳定性分析[J].水利学报,2016,47(8):977-985.
[12]Wang D J,Tang H M,Zhang Y H,et al.An improved approach for evaluating the time-dependent stability of colluvial landslides during intense rainfall[J].Environ Earth Sciences,2017,76(8):321.
[13]Bishop A W,Alpan I,Blight G E,et al.Factors controlling the strength of partly saturated cohesive soils[C]∥Research Conference on Shear Strength of Cohesive Soils.ASCE,1961:503-532.
[14]Fredlund D G,Morgenstern N R,Widger R A.The shear strength of unsaturated soils[J].Canadian Geotechnical Journal,2002,15(3):313-321.
[15]闫亚景,文宝萍,计博勋.基质吸力对非饱和重塑黄土抗剪强度的贡献[J].工程地质学报,2011,19(6):865-874.
[16]林鸿州,李广信,于玉贞,等.基质吸力对非饱和土抗剪强度的影响[J].岩土力学,2007,28(9):1931-1936.
[17]Montrasio L,Valentino R.A model for triggering mechanisms of shallow landslides[J].Natural Hazards and Earth System Sciences,2008,8(5):1149-1159.
[18]Montrasio L,Valentino R,Losi G L.Rainfall-induced shallow landslides:A model for the triggering mechanism of some case studies in Northern Italy[J].Landslides,2009,6(3):241-251.
[19]马雨露,赖成光,习树峰,等.南方高度城市化地区极端降雨特征分析及阈值确定:以深圳市为例[J].水资源与水工程学报,2017,28(2):76-81.