为研究膨润土防水毯(GCL)和水泥-膨润土防渗墙组成的新型复合垂直防渗墙中有机污染物的运移机理,分别考虑水泥-膨润土防渗墙和GCL作用,以及污染物击穿GCL复合垂直防渗墙迁移到零浓度的潜水层中,建立了污染物在GCL复合垂直防渗墙中的一维运移模型,并给出了出口边界采用混合边界条件时的一维解析解,所得结果与GeoStudio软件数值模拟结果高度吻合,由此验证了解析解的正确性,进而采用一维解析解开展了参数分析。研究结果表明:GCL层可以进一步提高垂直防渗墙的防污效果;有机污染物的半衰期主要影响水泥-膨润土防渗墙中的浓度分布,水泥-膨润土防渗墙的墙厚与渗透系数对墙体内部的污染物浓度分布和出口边界的污染物通量的影响较大。
Abstract
The aim of this research is to investigate the transport mechanism of pollutants in composite vertical barrier wall formed by combination of cement-bentonite cut-off wall and geosynthetic clay liner(GCL).A 1-D transport model of pollutants in GCL composite vertical barrier wall was established in consideration of the respective functions of cement-bentonite impervious wall and GCL to simulate pollutants breaking through the GCL composite vertical barrier wall and transporting into the phreatic layer with zero concentration.The analytical solution was obtained when mixed boundary condition was adopted for outlet boundary and was found to be in good agreement with the numerical results of GeoStudio,hence verifying the feasibility of the solution.Parameter analysis manifested that GCL could further improve the efficiency of GCL composite vertical barrier wall.The half-life of organic pollutants mainly affected the concentration distribution of pollutants in the cement bentonite anti-seepage wall;the thickness and permeability coefficient of cement bentonite barrier wall significantly affected the concentration distribution of pollutants inside the wall and the pollutant flux at the outlet boundary.
关键词
垃圾填埋场 /
GCL复合垂直防渗墙 /
污染物 /
潜水层 /
解析解
Key words
landfill treatment /
GCL composite vertical barrier wall /
pollutant /
phreatic aquifer /
analytical solution
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基金
国家自然科学基金项目(41877255,52078182);国家重点研发计划项目(2019YFC1805004)
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