降雨条件下膨胀土生态边坡湿度演化规律及稳定性分析  

Moisture change law and slope stability analysis of expansive soil ecological slope under rainfall

作　　者：杨果林[1] 李亚龙 赵天雨 段瑞凯 李海峰[1] YANG Guolin;LI Yalong;ZHAO Tianyu;DUAN Ruikai;LI Haifeng(School of Civil Engineering,Central South University,Changsha 410075,China;China Railway 9th Bureau Group 1th Building Co.,Ltd.,Shenyang 110013,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中铁九局集团第一建设有限公司,辽宁沈阳110013

出　　处：《铁道科学与工程学报》2023年第11期4412-4425,共14页Journal of Railway Science and Engineering

基　　金：国家重点研发计划项目(2019YFC1509800);国家自然科学基金资助项目(51878667);中铁九局集团有限公司技术开发课题(XKGT-07-GGB2022-037)。

摘　　要：降雨条件下的雨水入渗是膨胀土边坡浅层溜坍的重要因素之一。为研究采用2种常见护坡植物条件下边坡雨水入渗湿润锋的迁移规律,利用工程边坡原位监测试验采集的实时数据,对降雨入渗边坡时空响应变化规律进行分析。同时,通过室内试验测定根土复合体的物理力学参数,采用有限元软件对原型生态防护膨胀土边坡进行降雨入渗条件下的流固耦合计算,重点分析在经历真实降雨后的4种生态防护工况下膨胀土边坡滑动面位置和安全系数变化;然后在模型边坡内设立监测断面监测不同深度的根土复合体饱和度随时间的变化规律,再引入相同位置的实时监测数据进行对比,综合确定夹竹桃生态边坡的固土影响范围。研究结果表明:能使3种类型边坡体积含水率发生变化的降雨为中到大雨(10~<50 mm/d),小雨(<10 mm/d)无法使边坡浅层含水率发生改变。生态边坡在长期降雨条件下含水率变化量小于素土边坡,而短时降雨(≤24 h)的变化量又大于素土边坡;小叶女贞护坡的含水率变化量小于夹竹桃护坡,护坡效果更好。实际降雨条件下,生态边坡的安全系数大于素土边坡,说明植物根系对边坡稳定具有提高作用。模型边坡的饱和度动态变化规律与监测数据吻合,根系深度0.2 m所代表的根系密集生长范围与实际边坡饱和度沿深度的分布规律相同,能够在模拟中反映夹竹桃根系的固土影响范围。研究结论可为降雨条件下膨胀土路堑边坡生态防治措施的研究提供参考和分析依据。Rainfall infiltration is one of the important factors in topsoil slip of expansive soil slopes.In order to study the migration law of wetting front under rainfall infiltration on ecological protection slope,the spatiotemporal response law of soil moisture content of slope was analyzed by using the real-time data collected by in-situ monitoring of engineering slope.At the same time,the physical and mechanical parameters of the root-soil composite were determined by laboratory tests.The fluid-structure interaction model under rainfall infiltration on the prototype ecological protective expansive soil slope was calculated by finite element software,focusing on the analysis of the trend of sliding surface position and safety factor of the ecological slope after rainfall.Finally,the time-variant data of soil saturation at the monitoring point location in the model slope was compared with the real-time monitoring data of the same location,and then the soil reinforcement depth of the ecological slope of oleander was comprehensively determined.The results of the study show that the rainfall that can cause changes in the volumetric moisture content of the three types of slopes is moderate to heavy rain(10~<50 mm/d).The light rain(<10 mm/d)cannot cause changes in the shallow moisture content of the slope.The variation of water content of ecological slope under long-term rainfall condition is smaller than that of vegetation slope,while the variation of short-time rainfall(≤24 h)is larger than that of vegetation slope.The variation of water content of ligustrum quihoui carr slope is smaller than that of oleander slope,and the slope protection effect is better.The safety coefficient of the ecological slope is greater than that of the plain soil slope under the actual rainfall conditions,which indicates that the plant root system has an improvement effect on the slope stability.The dynamic variation of saturation of the model slope matches with the monitoring data,and the dense-branched depth of the root system represented b

关 键 词：降雨入渗 生态防护 原位监测 边坡稳定性 根系固土机理 

分 类 号：TU43[建筑科学—岩土工程]