降雨条件下黄土边坡的稳定性分析

摘要

Rainfall is an important factor influencing slope stability,rain infiltration makes the soil saturation increase and increase of soil moisture and the decrease of shear strength when the rainfall intensity and duration exceed a certain degree,leading to slope instability. Combining with the landslide of Lanzhou Forest of Steles treatment engineering,according to rainfall intensity and duration of that of the shallow stratum of the slope was obtained water content changes,using the unsaturated soil shear strength theory,combined with finite element the shear strength reduction of rain-fall,under the conditions of the loess slope stability was analyzed and the slope instability was forecasted. The results show that a)under the condi-tions of continuous rain,slope deformation and destruction are the main body of increased water content of the slope;b)as the water content to be the main control parameters of the shear strength,set up the slope soil total cohesion,internal friction angle and sustained rainfall time relationship, with the finite element analysis,get the time of slope destruction,can get for continuous rainfall condition of soil slope reinforcement protection and instability forecast to provide the reference;c)the safety coefficient got by traditional FEM strength reduction method in slope stability analysis can-not get exactly the effects of the stability of the slope strength and it can only explain whether the slope is damaged.%降雨是影响边坡稳定性的重要因素，雨水入渗使土体饱和度增大、含水量增加、抗剪强度下降，当降雨强度和持续时间超过临界值时，便导致边坡失稳。结合兰州某滑坡治理工程，根据降雨强度和持续时间计算边坡浅层土体在不同时刻的含水量，运用非饱和土抗剪强度理论，对降雨条件下的黄土边坡的稳定性进行了分析。结果表明：持续降雨条件下边坡的变形破坏主要是边坡土体含水量增加引起的；把含水量作为抗剪强度的主要控制指标，建立边坡土体的黏聚力和内摩擦角与降雨持续时间的关系，进行有限元模拟分析，得到边坡安全系数，可为持续降雨条件下黄土边坡的防护和失稳预测提供参考；传统的有限元强度折减法得到的安全系数不能准确反映边坡稳定性的强弱，只能说明边坡是否破坏。