摘要
降雨是诱发边坡滑坡最常见的因素,降雨入渗会增加非饱和土的渗透力,降低非饱和土的基质吸力,从而降低边坡的稳定安全系数,导致边坡破坏。本文基于Green-Ampt入渗模型,考虑了降雨强度与降雨持时的作用,建立了降雨条件下浅层滑坡的概念模型,引入了多层非饱和土计算方法,推导了降雨导致的积水前后边坡稳定安全系数随降雨持时变化的关系式。通过对数值结果和模型结果进行比较发现,二者有较好的一致性。同时,对降雨强度进行研究发现,降雨强度小于边坡表面入渗速度时,降雨完全入渗,且基质吸力不断降低,由于渗透系数相差较大,湿润锋到达土层交界面处时,会在次表面产生积水;当边坡表面积水后,此时入渗速度主要受土层中最小渗透系数影响,入渗速度不断减小,直至与该渗透系数数值相等,降雨强度越大,达到积水的时间越短;当考虑平行边坡渗流时,在土层交界面处的稳定安全系数将发生突变,通过临界边坡稳定性降雨强度与降雨持时的关系曲线,揭示了降雨强度对边坡稳定性的作用规律,并给出三种警戒线,可为多层土质边坡稳定性研究提供一定的理论参考。
Rainfall is the most common factor inducing landslides.Rainfall infiltration can increase the permeability of unsaturated soil and reduce the suction of unsaturated soil matrix,thereby reducing the safety factor of the slope and leading to the destruction of the slope.In this paper,based on the Green-Ampt infiltration model,considering the effects of rainfall intensity and duration of rainfall,a conceptual model of shallow landslides under rainfall conditions is established.The relationship between the safety factor of the slope and the time-varying slope before and after water accumulation is derived.By comparing the numerical results with analytical solution,it is found that the numerical solution is in good agreement with analytical solution.Simultaneously,it is also found that when the rainfall intensity is less than the infiltration rate of the slope surface,the rainfall is fully infiltrated,and the matrix suction continues to decrease.However,due to the large difference in permeability coefficient at the interface of the soil layer,water accumulation will occur at the intersection surface.When the surface area of the slope is ponded,the infiltration rate is mainly affected by the minimum infiltration coefficient in the soil layer.The infiltration rate continuously decreases until it equals to the infiltration coefficient.The greater the rainfall intensity,the shorter the time reaches the ponded state.Considering the seepage of parallel slopes,it is found that the safety factor changes abruptly at the interface of the soil layer.Through the relationship between the critical slope stability rainfall intensity and rainfall time,the law of rainfall intensity on slope stability is revealed,and three warning lines are given.It provides a theoretical reference for the stability of multi-layer soil slopes.
作者
邵珠山
赵南南
吴奎
胡宏坤
秦溯
Shao Zhushan;Zhao Nannan;Wu Kui;Hu Hongkun;Qin Su(School of Civil Engineering,Xi’an University of Architecture and Technology,710055,Xi’an,China;Shaanxi Key Laboratory for Geotechnical and Underground Space Engineering,Xi’an University of Architecture and Technology,710055,Xi’an,China)
出处
《应用力学学报》
CAS
CSCD
北大核心
2021年第3期981-991,共11页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金(11872287)
陕西省科技厅重点研发计划(2019ZDLGY07-10)
西安建筑科技大学优秀博士学位论文培育基金(1608419002)。
关键词
边坡
降雨
入渗
稳定安全系数
多层非饱和土
slope
rainfall
infiltration
stability safety factor
multi-layer unsaturated soil
