摘要
压实黏土衬垫中裂隙的存在缩短了渗滤液击穿屏障的时间,减少了衬垫的服役时间。获得污染物沿裂隙迁移的参数,用于预测具有裂隙的压实黏土衬垫被渗滤液击穿的时间,对于防污屏障性能的评价具有重要的意义。采用不同孔隙率的砂模拟压实黏土中的裂隙,通过室内土柱实验分别获得Cl-在裂隙中的分子扩散系数和水动力扩散系数。试验结果表明,当裂隙开度d≥15 mm时,裂隙中Cl-的分子扩散系数与其在纯水中的分子扩散系数基本一致;当d〈15 mm时,分子扩散系数随裂隙宽度成指数下降。裂隙的水动力扩散系数约比分子扩散系数大3个数量级,当裂隙开度d≥10mm时,在不同水力梯度情况下,裂隙的水动力扩散系数基本维持不变,数值上与采用纯砂所获得的水动力弥散系数基本一致;当水力梯度i≥0.2时,水动力弥散系数的变化基本趋于稳定,不再受到裂隙宽度的影响。
The service period of landfill liners is reduced because of the fractures in compacted clay liners（CCL）, which shorten the breakthrough time of contaminants passing through the barrier. It is very important to predict the breakthrough time of the leachate for CCL with fractures when the parameters of contaminant transport of fractures are acquired. The experiment is carried out to obtain the coefficient of molecular diffusion and dispersion for chloridion in the fractures simulated by the sands with different porosities. The results show that the coefficient of molecular diffusion for chloridion is consistent when the chloridion passes through fractures with the width more than or equal to 15 mm and water, while the coefficient of molecular diffusion is reduced exponentially in the fractures with the width less than 15 mm. The coefficient of dispersion is approximately three orders of the magnitude more than that of molecular diffusion. Based on different hydraulic gradients, the dispersion coefficient of fractures with width more than or equal to 10 mm is essentially constant and almost equal to that acquired from the sand column experiment. While the hydraulic gradient is more than or equal to 0.2, the variation of dispersion coefficient is steady and not influenced by the width of the fractures.
作者
李磊
汪俊
黄勇
LI Lei;WANG Jun;HUANG Yong(School of Earth Sciences and Engineering,Hohai University,Nanjing 210098,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2018年第10期1836-1842,共7页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51478167)
关键词
压实黏土衬垫
裂隙
分子扩散系数
水动力弥散系数
compacted clay liner
fracture
molecular diffusion coefficient
hydrodynamic dispersion coefficient
