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.

Key words: landfill treatment, GCL composite vertical barrier wall, pollutant, phreatic aquifer, analytical solution