水泥土阻隔墙阻控地下水污染

GROUNDWATER POLLUTION CONTROL BY CEMENT SOIL BARRIER WALL

阻隔墙能够有效阻止地下水中的污染物扩散,以水泥土为研究对象,通过渗透实验、稳定性实验、吸附实验及工程案例研究了阻隔墙的性能。结果表明:随着水泥掺量增大,水泥土渗透系数不断降低,粉质黏土、黏质粉土、粉砂水泥掺量分别为12%、20%、25%时,抗渗效果较好。无侧限抗压强度随水泥掺量增加而增大,粉砂水泥土阻隔墙增幅显著。土壤黏粒含量越高,满足水泥土坍落度要求的水灰比越大。等温吸附符合Freundlich模型,水泥土对Cu^(2+)和Zn^(2+)吸附效果较四氯酚和六价铬显著。吸附动力学符合准二级吸附动力学方程,吸附过程主要为化学吸附,粉质黏土水泥土吸附Cu^(2+)和Zn^(2+)的平衡吸附量最高,分别为7.692,7.143 mg/g。工程应用表明,水泥土阻隔墙对地下水石油烃有机污染物具有显著的阻控效果,监测井检测浓度均低于风险控制值。

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 Cu^(2+) and Zn^(2+) 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 Cu^(2+) and Zn^(2+) 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.