强降雨条件下多台阶黄土边坡离心模型试验研究  

Experimental Study on Multi-stage Loess Slope Centrifuge Model Under Heavy Rainfall

作　　者：徐涛 魏静[2] 王振坤 XU Tao;WEI Jing;WANG Zhen-kun(China Railway Construction Investment Group Co.,Ltd.,Beijing 100855,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;College of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]中国铁建投资集团有限公司,北京100855 [2]北京交通大学土木建筑工程学院,北京100044 [3]同济大学土木工程学院,上海200092

出　　处：《公路交通科技》2024年第9期97-105,共9页Journal of Highway and Transportation Research and Development

基　　金：中国铁建投资集团有限公司科技研发项目(2020-C10)。

摘　　要：为探究强降雨条件下多台阶黄土边坡变形及稳定性,设计了离心机载降雨模拟装置,以在建吴华高速公路多台阶超高黄土边坡为原型,开展了强降雨条件下多台阶黄土边坡离心模型试验,研究了降雨条件下多台阶黄土边坡的含水率、土压力和位移的时程变化特性,对比分析了预设节理的存在对黄土边坡稳定性的影响。研究结果表明,强降雨条件下,边坡表层土体体积含水率迅速升高,形成暂态饱和区,在入渗阶段,湿润锋不断下移,土体内部孔隙水在重力作用下向边坡底部入渗,且坡脚处入渗速率最快,坡表中部最慢,其体积含水率较饱和状态减小了约6%;坡体土压力受土体含水率和表层土体冲蚀共同影响,在降雨阶段缓慢增长,而在冲蚀阶段快速降低;相较于无节理边坡,节理的存在为雨水入渗提供了优势渗流通道,加速了雨水向下入渗速率,含节理边坡更易被降雨冲蚀,其沉降增长速率更明显,土压力降低幅度更大,降雨结束时含节理边坡的坡顶沉降量较无节理边坡增加了约20%;强降雨条件下多台阶黄土边坡整体稳定性较好,在雨水溅蚀和径流冲刷等的共同作用下,降雨诱发多台阶黄土边坡的变形破坏模式呈现为边坡冲蚀引起的溜滑破坏,且主要集中于坡脚和第一级台阶坡面处,故在实际工程中应加大对边坡坡面和坡脚处的防护。To investigate the deformation and stability of multi-stage loess slopes under heavy rainfall,the rainfall simulation device mounted on centrifuge was designed.Taking the in-construction multi-stage ultrahigh loess slope of Wuqi-Huachi expressway as the prototype,the centrifuge model tests were conducted to study the temporal variations in moisture content,soil pressure,and displacement of multi-stage loess slopes under rainfall.The comparative analysis was conducted to evaluate the influence of pre-existing joints on the loess slopes stability.The result indicates that the volumetric moisture content of slope surface soil layer rapidly increases under heavy rainfall,forming the transient saturation zone.During the infiltration phase,the wet front continuously moves downward,and the internal pore water infiltrates towards the slope bottom under the gravity,with the fastest infiltration rate at the slope toe and the slowest in the middle of slope surface,resulting in a reduction of approximately 6%in volumetric moisture content compared with the saturated state.The soil pressure on slope body is jointly influenced by the soil moisture content and the surface soil layer erosion,showing the slow growth during rainfall phase and the rapid decline during erosion phase.Compared with the slopes without joints,the presence of joints provides the preferential flow channels for rainwater infiltration,accelerating the downward infiltration rate.The slopes with joints are more easily eroded by rainfall,exhibiting a more pronounced increase in settlement growth rate and a greater reduction in soil pressure.The settlement at slope top with joints increases by approximately 20%compared with the slopes without joints after rainfall.Overall,the stability of multi-stage loess slopes under heavy rainfall is satisfactory.Under the combined effects of rainfall splash erosion and runoff scouring,the deformation failure mode induced by rainfall in multi-tiered loess slopes manifests as slip erosion,primarily concentrated at the slope t

关 键 词：道路工程 变形规律 离心模型试验 黄土边坡 强降雨 

分 类 号：U419.4[交通运输工程—道路与铁道工程]