土-水特征曲线在雨后基坑边坡稳定性评价中的应用

为研究雨型和基坑坡顶硬化长度对非饱和土基坑稳定性的影响,采用GeoStudio中SEEP/W模块进行降雨模拟,得到雨后坡体孔隙水压力和体积含水率的分布特征。然后将降雨模拟结果导入到SLOPE/W模块中,结合固结快剪试验得到的抗剪强度参数进行数值计算,并对基坑边坡的稳定性进行评价。结果表明:瞬时强降雨入渗深度小,长时普通降雨的入渗深度大;坡顶硬化有利于限制雨水入渗,可减少入渗至滑面内的量,有利于基坑稳定;当坡顶硬化长度为3 m时,降雨对基坑稳定性影响不明显,长度为5 m时,基坑稳定性基本不受降雨的影响;基坑边坡土体初始含水率较低时,前期降雨对基坑稳定性不仅没有不良影响,反而有利于基坑稳定。最后,以实际滑坡为例,对模拟结果进行了验证并说明了坡顶硬化对基坑边坡稳定性的重要性。

Application of Soil-Water Characteristic Curve in Stability Evaluation of Foundation Pit Slope after Rain

The slope of the excavations often has the concrete surface layer and the hardened slope top which is impermeable to water. In order to study the effect of rain type and the length of hardened slope top on the stability of the unsaturated excavations,the rainfall simulation is obtained by GeoStudio SEEP/W module,and the distribution characteristics of the water pressure and volume moisture of the slope after the rain are obtained. Then,the rain simulation results are imported into the SLOPE/W module. The shear strength parameters obtained by the consolidated quick shear test are used in numerically calculation,and the stability of the excavations is evaluated. The results show that the depth of infiltration of instantaneous heavy rainfall is small,and the infiltration depth of ordinary rainfall is large in long periods. The hardened slope top tends to limit the infiltration of rainwater,reduce the infiltration at the slip surface,and is beneficial to the stability of the excavations. When the slope top hardening length is 3 m,the effect of rainfall on the stability of the excavation is not obvious,and when the length is 5 m,the stability of the excavation is basically not affected by rainfall. When the initial water content of the soil of the slope is low,instead of arousing adverse effect on the stability of the excavations,the early rainfall is beneficial to the stability of the excavations. Finally,taking the actual landslide as examples,the simulation results are verified and the importance of slope top hardening to the stability of the slope is explained.