降雨入渗参数对粗粒土路堤暂态饱和区影响的数值模拟

Numerical simulation of effects of rainfall infiltration parameters on transient saturated areas of coarse-grained soil embankment

为探讨降雨入渗条件下粗粒土路堤边坡暂态饱和区的形成条件,分析降雨入渗参数对暂态饱和区发展规律的影响,基于室内外试验数据与实际气象数据,拟定不同的数值计算方案,采用降雨入渗理论对降雨入渗参数影响下粗粒土路堤边坡雨水入渗过程进行数值模拟。结果表明:降雨强度q与饱和渗透系数ksat的比值是决定路堤内雨水入渗方式及暂态饱和区形成的关键因素,当q/ksat≥1.5时,路堤边坡表面及坡脚水平面将形成一定深度的暂态饱和区,暂态饱和区的形成增大了路堤发生失稳的可能;降雨入渗仅会引起路堤边坡坡面以下水位大幅度上升,对路面中部以下地下水位影响有限;路堤边坡暂态饱和区的扩展速度主要取决于q与ksat的大小,而暂态饱和区形成的时间与扩展面积则受到降雨强度、降雨历时与饱和含水率的共同影响。

In order to explore the formation conditions of transient saturated areas of a coarse-grained soil embankment slope with rainfall infiltration, and to investigate the effects of rainfall infiltration parameters on the development of the transient saturated areas, we designed various numerical calculation schemes using field and laboratory data and actual meteorological data, and conducted numerical simulation of the rainfall infiltration process of the coarse-grained soil embankment slope under the influence of rainfall infiltration parameters based on the theory of rainfall infiltration. The results show that the rainfall infiltration direction and formation of transient saturated areas were determined by the ratio of rainfall intensity （q） to saturated permeability coefficient （ksat）. When q/ksat≥1. 5, transient saturated areas with a certain depth formed at the embankment slope surface and slope toe. The formation of the transient saturated areas increased the possibility of embankment failure. The rainfall infiltration only caused the water level under the embankment slope surface to increase significantly, but had limited influence on the groundwater level below the central road. The expanding speed of the transient saturated areas was mainly determined by q and ksat, while the formation time and expansion area of the transient saturated areas were influenced by q, rainfall duration, and saturated water content.