磷酸镁水泥固化铜污染土的冻融稳定性研究  

Study on freeze-thaw stability of Cu-contaminated soil solidified by magnesium phosphate cement

作　　者：侯世伟[1] 张皓[1] 杨镇吉 张瑀哲 张玉龙 丁兆洋[2] HOU Shiwei;ZHANG Hao;YANG Zhenji;ZHANG Yuzhe;ZHANG Yulong;DING Zhaoyang(School of Civil Engineering,Shenyang Jianzhu University,Shenyang,Liaoning 110168,China;Test and Analysis Center,Shenyang Jianzhu University,Shenyang,Liaoning 110168,China)

机构地区：[1]沈阳建筑大学土木工程学院,辽宁沈阳110168 [2]沈阳建筑大学分析与检测技术研究中心,辽宁沈阳110168

出　　处：《岩石力学与工程学报》2020年第S01期3123-3129,共7页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点研发计划(2018YFD1100404);国家自然科学基金资助项目(51308355);辽宁省自然科学基金项目(20170540736)。

摘　　要：为研究重金属污染土的固化强度和长期稳定性,以磷酸镁水泥固化铜污染土为研究对象,进行基于冻融循环次数、磷酸镁水泥掺量、铜离子浓度等因素的强度和扫描电镜试验,给出冻融循环作用下固化铜污染土的无侧限抗压强度特征以及微观机制。研究表明:随着冻融循环次数增多、铜离子浓度的提高及磷酸镁水泥掺量的减少,固化土的无侧限抗压强度逐渐降低。3和12次冻融循环下固化污染土的无侧限抗压强度降低率最小,无侧限抗压强度降低率在冻融循环次数为6~9次时达到峰值。磷酸镁水泥固化低浓度重金属铜污染土的抗冻稳定效果显著,随金属离子浓度的增加固化土的冻融稳定性能降低。基于扫描电镜试验得到固化污染土的微观孔隙结构,当铜离子浓度0.5%且冻融6次时,磷酸镁水泥掺量从5%到20%,微观统计孔隙所占百分比减小17.43%,验证了强度变化机制。研究成果为我国冻土地区的重金属污染场地固化处理的长期稳定性评价提供参考,具有理论指导意义和工程应用价值。In order to study the strength characteristics and long-term stability of heavy metal contaminated soil,a series of strength and scanning electron microscope experiments were carried out based on solidified Cu-contaminated soil with magnesium phosphate cement.The freeze-thaw cycle times,magnesium phosphate cement content and copper ion concentration were considered as experiment effect factors,and the strength and microstructure of Cu-contaminated soil solidified were studied under freeze-thaw conditions.The results show that the unconfined compressive strength of solidified soil decreases gradually with the increase of freeze-thaw cycle times and copper ion concentration or the decrease of magnesium phosphate cement content.Under 3 and 12 freeze-thaw cycles,the reduction rate of unconfined compressive strength of solidified contaminated soil is the smallest,and the reduction rate of unconfined compressive strength reaches the peak value when the number of freeze-thaw cycles is 6 to 9 times.The freeze-thaw stability of Cu-contaminated soil of low concentration heavy metal that cured by magnesium phosphate cement is remarkable,and the freeze-thaw stability of solidified soil decreases with the increase of metal ion concentration.The micropore structure of solidified contaminated soil was obtained based on the scanning electron microscope experiment.The content of magnesium phosphate cement increased from 5%to 20%,and the percentage of microscopic statistical pores decreased by 17.43%when the concentration of copper ion was 0.5%and freeze-thawed for 6 times,so the mechanism of strength change is verified.The research provided theoretical and engineering application reference for frozen-thawed areas of northern China to evaluate the long-term stability of solidification treatment of heavy metal contaminated sites.

关 键 词：土力学 冻融循环 重金属污染土 固化作用 无侧限抗压强度 微观孔隙 

分 类 号：TU43[建筑科学—岩土工程]