降雨条件下土质挖方边坡的稳定性分析  

Stability analysis of soil excavation slope under rainfall

作　　者：索增辉[1,2] 徐晓琪 SUO Zenghui;XU Xiaoqi(No.3 Geological Exploration Institute,Henan Provincial Bureau of Geoexploration and Mineral Development,Zhengzhou 451464,Henan,China;Engineering Technology Research Center for Deep Hole Drilling for Metal Minerals in Henan Province,Zhengzhou 451464,Henan,China;School of Civil Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]河南省地质矿产勘查开发局第三地质勘查院,河南郑州451464 [2]河南省金属矿产深孔钻探工程技术研究中心,河南郑州451464 [3]天津大学建筑工程学院,天津300072

出　　处：《矿产勘查》2024年第7期1278-1285,共8页Mineral Exploration

基　　金：2022年浙江省教育厅高校访问工程师“校企合作项目”(FG2022332)资助。

摘　　要：边坡开挖会对原始斜坡体产生卸荷效应,降低了土坡抵抗外界荷载的能力,降雨入渗后易引发灾害,给边坡安全施工造成威胁。本文采用非饱和土抗剪强度理论,结合Morgenstern-Price条分法,对不同放坡角度下边坡的稳定性进行分析,同时采用具有不同降雨峰值的两组72 h实测降雨值,动态分析了边坡安全系数,同时探讨了孔隙水压力的变化规律。结果表明:(1)土体饱和度随基质吸力增加而不断减小;(2)由于粉细砂渗透系数大,同一吸力水平下,饱和度下降最快,其次为淤泥质壤土,而黏土的饱和度下降最慢,储水能力最好;(3)随着坡角增大,边坡的潜在滑动面会逐渐靠近开挖形成的临空面,即滑坡的体积会减小,边坡的安全系数越低;(4)总体上随着降雨时长增大,边坡的安全系数呈逐渐减小的趋势,但局部出现了回升的现象。因此在进行实际切坡工程时,应当尽量降低坡角来保持边坡稳定性,对于需要留取较陡边坡的工程,应采取相应的加固措施来防止边坡出现滑坡等灾害。同时,采用实际降雨数据对边坡稳定性分析能够真实反映边坡安全系数边坡变化,对边坡稳定性设计具有实际意义。Slope excavation can cause unloading effects on the original slope mass,reducing the slope′s ability to resist external loads and making it prone to disasters after rainfall infiltration,thereby posing a threat to the safe construction of the slope.This paper uses the theory of unsaturated soil shear strength combined with the Morgenstern-Price method to analyse the stability of slopes under different slope angles.It also uses two sets of 72-hour measured rainfall data with different peak values to dynamically analyse the safety factor of the slope and explore the pattern of changes in pore water pressure.The results show:(1) Soil saturation decreases continuously with increasing matrix suction;(2) Due to the high permeability coefficient of fine sand,the rate of saturation decrease is fastest at the same suction level,followed by silty loam,while clay has the slowest rate of saturation decrease and the best water storage capacity;(3) As the slope angle increases,the potential sliding surface of the slope gradually approaches the free face formed by the excavation,thereby reducing the volume of the landslide and lowering the safety factor of the slope;(4) Overall,the safety factor of the slope shows a general decreasing trend as the duration of rainfall increases,but local recoveries are observed.Therefore,in practical slope cutting projects,it is advisable to reduce the slope angle as much as possible to maintain slope stability.For projects that require steep slopes,appropriate reinforcement measures should be taken to prevent disasters such as landslides.In addition,the use of actual rainfall data for slope stability analysis can truly reflect the changes in the safety factor of the slope,which is of practical importance for slope stability design.

关 键 词：挖方边坡 降雨入渗 边坡稳定性 Morgenstern-Price法 孔隙水压力 

分 类 号：U417.1[交通运输工程—道路与铁道工程]