粗石英砂层厚度及倾角对核废物处置库顶盖毛细屏障效应的影响

Effects of thickness and slope of the coarse layer cover of radioactive waste disposal site on its capillary barrier function

毛细屏障作为核废物处置库顶盖的工程屏障之一,已经在国内外得到了广泛应用。采用箱体实验方法,研究了非饱和稳定流条件下粗石英砂层厚度和倾角对毛细屏障效应的影响。结果表明,随着粗石英砂层厚度的增大,水分的相对绕流量增大,毛细屏障效应增强;随着粗石英砂层倾角的增大,其表面积水减少,水的横向流动能力增强,毛细屏障效应增强。

Many nuclear waste disposal site covers are constructed to provide desired capillary barriers function that reduces water infiltration. Typically a fine-grain soil layer is placed on a coarse layer cover to provide the desired capillary barrier function. Upon reaching the fine-coarse interface, infiltrating water would be held at the interface by capillary forces and move laterally along the slope instead of downward into the coarse layer. Steady state unsaturated infiltration tests were conducted to determine the effects of thickness of coarse layer and inclination angle on the capillary barrier function of the fine and coarse quartz sand layers. The capillary barrier function effectiveness was depend- ent on the matrix suction head under the unsaturated condition. The relative dispersive flow increased with thickness of the coarse layer enhancing the capillary barrier effectiveness. A larger inclination angle of the coarse layer resulted in less water accumulated at the interface with more water drained laterally and thus greater efficiency of the capillary barrier function.