固化/稳定化铅污染土的浸出和力学特性研究

Study on leaching and mechanical characteristic of solidified/stabilized lead contaminated soil

为克服现有固化剂在重金属污染土治理和资源化利用中的不足,采用了新型固化剂对铅污染土进行固化处理。基于无侧限抗压强度试验、浸出试验,研究了初始铅污染浓度、污染土粒径、养护龄期对固化后污染土性能的影响。试验结果表明:固化体试样的强度随初始铅污染浓度、污染土粒径的增加而减少,随养护龄期的增加而增大;固化体试样的应力—应变曲线呈现出随初始铅污染浓度和养护龄期显著变化的规律,随着初始铅污染浓度增加,固化体抗压强度减小,破坏应变增大,应力—应变曲线变平缓,峰值不明显。随着养护龄期增加,峰值应变减小,固化体应力—应变曲线峰值后表现为下降段较陡;浸出浓度随污染土粒径、养护龄期的增加而降低,随铅含量的增加而增加,但浸出浓度均远低于浸出安全标准限值。

To overcome the shortcomings of existing curing agent used in the treatment and resource utilization of heavy metal contaminated soil,a new curing agent was used to cure the Pb contaminated soil.Unconfined compressive strength test and leaching test were both conducted to investigate the variation of mechanical properties of lead-contaminated soils treated under different conditions of lead concentration,soil particle size and curing time.The results show that the strength of the solidified sample decreases with the increase of initial lead concentration and soil particle size,and increases with the increase of curing age.The stress-strain curve of the solidified sample shows a significant change with the initial lead concentration and the curing age.With the increase of the initial lead concentration,the compressive strength of the solidified sample decreases,the peak strain increases,and the stress-strain the curve becomes flat and the peak is not obvious.As the curing age increases,the peak strain decreases,and the peak of the stress-strain curve of the solidified sample appears to be steeper in the falling section.The leaching concentration decreased with the increase of contaminated soil particle size and curing age,and increased with the increase of lead content,but the leaching concentration was much lower than the leaching safety standard limit.