稳定剂协同水泥固化/稳定化重金属污染土壤的工程特性

采用稳定剂（SR）协同水泥（PC）固化/稳定化重金属污染土壤，以Pb、Zn浸出毒性和药剂吨处理成本为综合指标确定PC和SR的最优配比，并对固化土体进行无侧限抗压强度、不固结不排水三轴压缩实验和柔性壁渗透实验，探讨固化土体强度以及渗透特性。结果表明，最优配比为SR掺量 2.5%，PC掺量8%；最优配比下固化土体中重金属铅锌的浸出浓度分别降低97.5%和74.5%，均低于固体危险废物浸出标准值。其养护28 d无侧限抗压强度达到1 080 kPa，比未固化土体对应值高9.6倍；随着PC掺量增加，固化体的有效黏聚力及有效内摩擦角均不断增大，其中最优配比固化土体有效黏聚力达到216.9 kPa，有效内摩擦角为34.8°。加入稳定剂SR使固化体渗透系数增大，但随着PC掺量增加，渗透系数急剧降低。其中最优配比固化土体渗透系数相对未固化复合污染土体降低一个数量级至10-6cm·s-1，可有效增强土体的防渗阻隔能力，提高稳定化土壤的安全利用率。

Engineering characteristics of stabilized contaminated soil with heavy metals by cement and SR

The stabilizer(SR)and cement(PC)were used as additive to stabilize contaminated soil with heavy metals. The optimum ratio of cement to SR was determined by testing the cost of the binders as well as the leaching toxicity of lead and zinc. The permeability and strength properties of the solidified soil were evaluated by unconfined compressive strength, unconsolidated-undrained(UU)triaxial tests, and a triple type flexible-wall permeameter test. The optimum proportion of cement to SR was 8% cement to 2.5% SR, which could decrease the leaching concentrations of Pb and Zn by 97.5% and 74.5%, respectively. In this conditions, the 28 d unconfined compressive strength of the solidified body(up to 1 080 kPa)was 9.6 times higher than that without treating. An increase in the PC mixing ratio improved the effective cohesion and friction angel, which in turn improved the strength of the stabilized soils. Adding SR improved the penetrance of the stabilization, whereas an increase in the PC mixing ratio effectively decreased the permeability of the treated soil. Under the optimum proportion, the permeability coefficient of the stabilized soil was reduced to 10-6 cm·s-1, which was relatively lower than the one without treating. This could enhance the barrier ability of the soil, and improve the safety utilization.