固化/稳定化和软土加固污染土的强度和浸出特性研究

Strength and leaching performances of stabilized/solidified(S/S)and ground improved(GI)contaminated site soils

研究了固化/稳定化和软土加固两种土壤搅拌技术修复英国Yorkshire郡的重金属及有机物复合污染土的强度和浸出特性。使用的固化剂为氧化镁和高炉矿渣。选取现场固化/稳定化和软土加固处理后取回实验室分别养护1.5 a和1a的试样,开展了无侧限抗压强度和浸出试验,研究了场地深度对两种技术处理复合污染土的强度和浸出特性的影响。研究结果表明,氧化镁–高炉矿渣可以显著提升污染土强度,固化土无侧限抗压强度均值均超过英国的设计值350 kPa;浸出结果表明修复后除部分样中Ni不达标,Cu和Pb的浸出浓度均达到英国饮用水标准。氧化镁和高炉矿渣联合使用可以有效固化Ni。相较于软土加固技术,固化/稳定化技术修复污染土pH值更高、Ni浸出浓度和有机物浸出浓度更低,在固化重金属和有机物复合污染土方面效果更加显著。场地深度对修复后污染土的性质影响微弱。

The soil mixing technologies(SMT)such as stabilization/solidification(S/S)and ground improvement(GI)are used to treat heavy metal and organic-contaminated site soils in the Castleford,Yorkshire site,UK.The ground granulated blastfurnace slag(GGBS)and magnesia(MgO)are used in this study.The unconfined compressive strength(UCS)tests as well as the BS EN12457 batch leaching tests are conducted on the S/S contaminated soils at 1.5 years and GI soils at 1 year to assess the influences of different depths on the strength and leaching performances of these samples.The results show that the MgO-GGBS can significantly improve the strength of contaminated soils as the average UCS of MgO-GGBS-treated samples exceeds 350 kPa suggested by the UK design standard.Moreover,except part of Ni,the leaching concentrations of Cu and Pb are able to meet drinking water standard of the England.The combination of Mg O and GGBS are found to be able to immobilize Ni efficiently.Compared with the GI technique,the S/S technique can achieve higher p H,lower leaching concentration of both Ni and organic compounds,which is more effective in immobilizing heavy metals and organic compounds.The depth of the site has few influences on the properties of contaminated soils after remediation.