强降雨作用下堆积碎石土渗流规律研究

摘要

Heavy rainfall can change the permeability characteristics of aggregate gravel soil,which is the keyfactor triggering landslides,mudslides and other type of rainfallinduced disasters.This paper explores the dynamicmechanism of landslide induced by rainfall infiltration.Selfmade onedimensional permeameter and twodimensional slope model are used for the representative gradation gravel soil test close to Shuizuwan Tunnel.Then,further research focuses on the seepage regulation of aggregate through Seep/w software.The results show that:there is a stepladder trend between wetting front and time curve.More specifically,wetting front migration rate canrapidly increase with the sudden increase of the topsoil moisture to a maximum.It can slowly decrease withincreased pressure.Finally the wetting front migration rate can slightly increase with the decreased pressure.Theaverage rate of wetting front migration approaches a linear growth with the increased rainfall intensity.Developmentof soil settlement deformation passes through three stages.They are slow growth,sharply rises and graduallystagnation.The onedimensional infiltration rate has a power,logarithmic and linear relations with the slope infiltration rates at top,middle and toe of the slope,respectively.The final depth of rainwater infiltration is the toeof slope,the top of slope and midslop in order descending.%强降雨致堆（残坡）积碎石土渗透特性改变是触发滑坡、泥石流等降雨诱发型灾害的关键因素。为探究降雨入渗诱发滑坡的动态机制，通过自制一维渗透仪与二维边坡降雨入渗模型，对水竹湾隧道旁具有级配代表性的碎石土进行强降雨入渗试验，并通过 Seep／w软件进一步分析堆积碎石土湿润锋迁移入渗规律。研究结果表明：一维入渗深度－时间曲线存在阶梯状趋势，即湿润锋迁移速度首先随表层土含水率的突增迅速增加至最大值，然后缓慢减小，最后湿润锋迁移速度略微增大；湿润锋平均迁移速率随雨强的增大趋近线性增长；碎石土沉降变形在入渗过程中经历缓慢增长、急剧增大、逐渐停滞3个阶段；坡顶、坡腰及坡脚处入渗速率与一维入渗速率分别满足指数关系、对数关系及线性关系；雨水最终入渗深度由大到小依次为坡脚、坡顶、坡腰。