中文摘要：

降雨是诱发土质边坡失稳的主导因素之一,研究降雨入渗对土质边坡稳定性的影响有着重要意义。以青海西宁盆地黄土边坡为例,结合野外现场试验和室内直剪试验,研究了降雨入渗对坡体含水量和抗剪强度的影响,采用FLAC2D软件模拟分析了降雨前后边坡的应力、位移分布特征,并通过计算安全系数对边坡进行稳定性评价。研究结果表明,雨水入渗150 min内边坡表层土层含水量急剧增加,150 min后其变化趋势逐步变缓,较深层土层含水量随雨水入渗时间呈持续缓慢增加的趋势。对于同一层土体而言,雨水入渗深度随降雨历时的增大而增加,且表层土体中雨水入渗速度先快后慢。表层土体含水量每增加1.01%,其粘聚力减小13.53 k Pa,土体抗剪强度降低16 k Pa,说明土体抗剪强度对含水量的变化极为敏感。二维有限元模拟和分析结果表明,在自重应力作用和雨水入渗条件下,研究区坡脚处出现应力集中现象,且降雨后边坡位移量、应力集中范围及应力大小明显大于降雨前,而降雨后边坡稳定安全系数比降雨前降低了21.6%,说明降雨入渗对边坡的稳定性影响较大。

英文摘要：

The study of rainfall infiltration is of great significance in the soil-slope stability since rainfall is one of the dominant factors affecting the soil-slope instability. Loess slope in the Xining Basin is taken as an example, and water content in the slope and shear strength triggered by rainfall infiltration are examined based on field tests and direct shear laboratory tests. Simulation analyses of the stress and displacement distribution characteristics before and after raining are carried out by using the FLACzD software and the safety coefficient is calculated for the evaluation of the soil slope stability. The results show that the soil water content in the surface soil layer increase sharply at the beginning 0 -150 rains of infiltration time, then the increasing tendency of water content becomes slow after 150 min. At the depths of 60 cm and 90 cm of the surface soil, a slow increasing and sustain trend exists. With regard to the same soil mass, the infiltration depth increases with the duration of rainfall. In addition, the rainfall infiltration rate of surface layer is fast at the beginning and then becomes slow. The surface soil cohesion decrease by 13.53 kPa and the shear strength reduces by 16 kPa for each additional 1.01% of water content, indicating that the soil shear strength is extremely sensitive to water content changes. The 2-D finite element modelling results also show that the stress concentrates at the slope foot of the study area under the effect of gravity stress and the condition of rainfall infiltration. Moreover, the amount of slope displacement, stress concentration ranges and its values are obviously greater than those before raining, and the safety-coefficient of the slope stability decreased by 21.6% , indicating that rainfall infiltration has a great influence on soil-slope stability.