关键词: 重金属污染土, 固化, NaCl浸泡, 无侧限抗压强度, 毒性特征沥滤试验（TCLP）

Abstract: The problem of environmental pollution results in the accumulation of heavy metal ion in soil, which not only influences the engineering properties of soil, but also threatens the health of human beings. Currently the cement solidification technology (S/S method) is adopted to treat heavy metal-contaminated soils. However, with the increase of concentration of corrosive salt in the groundwater, the solidified heavy metal-contaminated soil can be influenced by the corrosive salt ions, resulting in the deterioration of the strength of soil and leaching-out of the heavy metal ions. A series of systematic laboratory tests is conducted to investigate the strength and leaching characteristics of chromium polluted soil solidified with cement after soaking in NaCl solution. The experimental results show that the unconfined compressive strength of chromium polluted soil solidified with cement decreases with the increase of the concentration of NaCl solution, and decreases at first and then increases with soaking time, and the minimum strength is determined after 7 d soaking. The results of the toxicity characteristics leaching procedure (TCLP) show that the concentration of Cr3+ in leachate increases with the increase of NaCl concentration, and decreases with the increase of soaking time. The pH value of leachate decreases with the increase of NaCl concentration, and decreases at first and then increases with soaking time, and the minimum concentration of Cr3+ is got when soaking 7 d. when the pH value of leachate is within the range of 4.0 to 5.5, the leaching quantity of Cr3+ decreases with the increase of pH value.

Key words: heavy metal polluted soil, solidification, NaCl soaking, unconfined compressive strength, toxicity characteristics leaching procedure (TCLP)