上覆强透水层的双层土质边坡降雨入渗特征

Rainfall Infiltration Characteristics of Double-Layered Soil Slope Covered by a Highly Permeable Stratum

为研究浅层强透水的双层土质边坡降雨渗流特征,建立均质粉土与砂土-粉土的土柱、边坡模型,依据基质吸力与含水率的控制方程,分析了土层渗透性、地下水、坡度对饱和区成形影响.结果表明:砂土-粉土柱产生饱和区,既因土层渗透差导致雨水在砂土底层蓄积,又因粉土表面的渗流速度陡降;砂土-粉土边坡饱和区在土层界面首先产生,在纵向上以界面为中心逐渐往各土层内扩展,同时沿土层界面往坡顶上发展,其延伸长度随着地下水位升高而逐渐增大,但地下水位2 m与1 m时,坡度越大,延伸长度越小;地下水位与坡度均影响土层界面的初始饱和度.

In order to study the rainfall infiltration characteristics of double-layered soil slope covered by a highly permeable stratum,the soil column and slope model of homogeneous silt and sand-soil were established respectively,and the governing equations according to the matric suction and water content were used to analyze the effect of permeability,ground water level and slope angle on the formation of saturated zone.The results showed that the formation of saturated zone in sand-soil column is caused by the water accumulation under the sand layer due to the permeability difference,and the dramatically decrease of seepage velocity in the surface of the silt layer.The saturated zone is initially formed in the interface of the soil layer in the sand-soil slope and develops along the interface till to the upper boundary of the slope.In the meanwhile,it gradually develops into the soil layers and up to the interface of layers in the longitudinal direction.The extension length along the soil interface gradually increases with the increase of the groundwater table,but when the groundwater table is 2 m and 1 m,the extension of the saturated zone is reduced with the increases slope angle.The initial saturation degree is affected by groundwater table and slope angle.