超声辅助复合淋洗对污染黏土的工程性质影响

Impact of Ultrasound-assisted Complex Leaching on Engineering Properties of Contaminated Clay

研究采用超声辅助复合淋洗剂(酒石酸、乙二胺四乙酸二钠(Na2EDTA)),对人工配制的Cu^(2+)、Ni^(2+)、Pb^(2+)重金属污染黏土开展试验,分析了在不同重金属离子浓度下,超声辅助复合淋洗前后土体pH值、液塑限、强度特性、压缩特性等工程性质的变化规律。试验结果表明:(1)超声淋洗修复后,污染黏土pH值显著降低,酸性淋洗剂会带来较严重的土壤酸化;(2)修复后土体液性指数增加,塑性指数降低;(3)超声淋洗修复后,土体抗剪强度降低,内摩擦角整体降低2°~3°;(4)孔隙比随固结压力增大而减小,重金属浓度越大,降低幅度越大;(5)修复后土体的压缩性增大,压缩系数增加,压缩模量降低。

The ultrasonic-assisted complex leaching agents(tartaric acid and ethylenediaminetetraacetic acid disodium salt(Na2EDTA))were employed to carry out experiments on contaminated clay containing heavy metals Cu^(2+),Ni^(2+),and Pb^(2+).The variation laws of engineering properties such as soil pH,liquid plastic limit,strength characteristics,and compression characteristics before and after ultrasonic-assisted complex leaching were scrutinized under different heavy metal ion concentrations.The results revealed:(1)Post ultrasonic-assisted complex leaching remediation,the pH value of the contaminated clay reduces significantly,with the acidic leaching agent inducing severe soil acidification.(2)Upon remediation,the soil's liquidity index increases while the plasticity index decreases.(3)After ultrasonic leaching remediation,the shear strength of the soil body reduces,with the overall internal friction angle decreasing by 2°~3°.(4)The porosity ratio decreases as consolidation pressure increases,with the reduction being more substantial the higher the heavy metal concentration.(5)Post-remediation,the compressibility of the soil body increases,as does the compression coefficient,while the modulus of compressibility diminishes.