GROUNDWATER POLLUTION CONTROL BY CEMENT SOIL BARRIER WALL

The barrier wall can prevent the diffusion of pollutants in groundwater effectively. Taking cement soil as the research object, the performance of the barrier wall was studied through laboratory penetration test, stability experiment, adsorption experiment and engineering case study. The results showed that with the increase of cement content, the permeability coefficient of cement-soil decreased continuously. Silty clay, clayey silty and silty sand with the cement content of 12%, 20% and 25% had good anti-permeability effect. The unconfined compressive strength increased with the increase of cement content, and the increase of compressive strength of silty sand cement soil barrier wall was obvious. The higher the clay content of soil, the greater the water-cement ratio was to meet the slump requirement of cement soil. The adsorption isotherms conformed to Freundlich model and the soil-cement adsorbed Cu²⁺ and Zn²⁺ better than tetrachlorophenol and Cr(Ⅵ). The adsorption kinetics conformed to the quasi-secondary adsorption kinetic equation and the adsorption process was mainly chemical adsorption. The equilibrium adsorption capacity of Cu²⁺ and Zn²⁺ adsorbed by silty clay cement soil was the highest (equaled to 7.692, 7.143 mg/g, respectively). The engineering application proved that the cement-soil barrier wall had remarkable control effect on petroleum hydrocarbon pollutants in groundwater and the detection concentration of monitoring wells was lower than the risk control value.