裂隙-黏土间水量交换率试验研究

Experimental study on water exchange between crack and clay

摘要:

裂隙为污染物(或降雨)入渗提供了重要的优势通道, 裂隙与土体之间的水量交换是裂隙中优势流的重要形式, 通过水量交换率进行数学描述.而目前的研究主要针对砂土中的圆柱形裂隙, 对于黏土中的平板形裂隙与黏土间水量交换率的研究目前处于空白.本研究针对黏土中裂隙的特点设计一套试验装置, 通过含水量传感器和张力计等测量系统, 定量研究裂隙-黏土间的水量交换率, 并得到裂隙-黏土间的界面渗透系数.研究发现水量交换率在渗透初期最大, 随着土中基质吸力的降低而降低, 裂隙-黏土间的界面渗透系数比土体的饱和渗透系数大一个数量级.当土体的初始含水量不同时, 随着渗透的进行, 不同初始含水量土体中的水量交换率趋于一致, 约为7×10^-6 s^-1

Abstract:

Cracks in soils provide significant preferential pathways for contaminant transport and rainfall infiltration, and water exchange between the cracks and soil matrix is crucial to estimate the preferential flow, which is often quantitatively described by a water exchange ratio. Current studies on the water exchange ratio mainly focus on the crack in sand, but the water exchange ratio between the crack and clay is still unclear. A novel experimental setup was designed with advanced water content and suction measuring system to investigate the water exchange of the deformable cracks in clays. Results show that the water exchange ratio is the highest at the initial stage and decreases with decreasing suction in the clay. The hydraulic conductivity of the crack-clay interface is about one order of magnitude larger than that of the saturated soil matrix. With different initial volumetric water content of soils, the water exchange ratio between crack and soil gradually decreases to 7×10^-6 s^-1 in the process of the infiltration experiments