摘要
重金属污染土不仅破坏环境健康,同时威胁岩土工程安全。通过控制变量法对砷(As)、镉(Cd)单一污染土和复合污染土的土壤化学、土体微观结构和击实特性对比分析,研究了不同重金属污染源、不同重金属浓度对污染土的击实特性影响规律及作用机制。结果表明:单一污染土中,As使土壤扩散双电层变厚,土颗粒呈絮凝状,小孔隙增加,小颗粒含量先增后减,最优含水率升高5.90%,最大干密度降低1.02%;Cd的作用效应截然相反,Cd压缩土壤扩散双电层,土体呈堆积状,小孔隙减少,小颗粒含量减少,最优含水率降低8.03%,最大干密度增加1.00%。Cd对土体击实特性影响大于As。复合污染土中,As、Cd对土体最优含水率的影响呈协同作用,而对最大干密度无明显相互作用关系。污染土宏微观联系桥梁可以通过分形维数与最大干密度建立,二者拟合结果为二次函数关系。研究成果可为重金属污染土环境与工程灾害防控提供关键参数和理论支撑。
Heavy metal contaminated soils not only destroy environmental health, but also threaten the safety of geotechnical engineering. The control variable method was used to study the compaction characteristics evolution and active mechanisms of arsenic(As) and cadmium(Cd) single and composite contaminated soils with different concentrations through soil chemistry,microstructure and compaction tests. The results showed that in single contaminated soil, the As could enhance optimal moisture content by 5.90%, but decrease the maximum dry density by 1.02% through thickening diffusion double electric layer, promoting small pores and fine aggregates in flocculated structure. The effect of Cd on the soil particles is opposite. Cd compressed the diffuseddouble layer so that the number of small pores and fine aggregates were reduced. As a result, the optimal water content was declined by 8.03% and the maximum dry density is increased by 1.00% of Cd contaminated soil. Furthermore, the influence of Cd on the compaction characteristics of soil is greater than that of As. For the As and Cd co-contaminated soil, As and Cd had synergistic interaction on the optimal moisture content, while no interaction on maximum dry density. The correlation between macro-and micro-characteristics of contaminated soil was established by fitting the relationship between fractal dimension and the maximum dry density with a quadratic function. The results of this study can provide key parameters and theoretical support for mitigating the environmental and engineering disasters of heavy metal contaminated soils.
作者
冯晨
李江山
刘金都
薛强
FENG Chen;LI Jiang-shan;LIU Jin-du;XUE Qiang(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;Hubei Province Key Laboratory of Contaminated Sludge and Soil Science and Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2022年第S02期171-182,共12页
Rock and Soil Mechanics
基金
国家重点研发计划(No.2019YFC1804002)
国家杰出青年科学基金项目(No.51625903)
国家自然科学基金面上项目(No.42177163)。
关键词
镉砷复合污染土
击实特性
扩散双电层
协同作用
分形维数
As and Cd co-contaminated soil
compaction characteristics
diffused double layer
synergistic interaction
fractal dimension
作者简介
第一作者:冯晨,女,1997年生,博士研究生,主要从事重金属污染土环境土工特性和修复方面的研究。E-mail:fengchen191@mails.ucas.ac.cn;通讯作者:李江山,男,1987年生,博士(后),研究员,博士生导师,主要从事污染土工程修复与固体废弃物资源化方面的研究。E-mail:jsli@whrsm.ac.cn
