Mn^(2+)污染后膨胀土力学特性的试验研究  

Mechanical Characteristics of Expansive Soil Contaminated by Manganese Ions

作　　者：蒋忠凯 肖桂元[1,2] 王一鹏 JIANG Zhongkai;XIAO Guiyuan;WANG Yipeng(Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,School of Civil Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China;School of Engineering,China University of Geosciences,Wuhan,Hubei 430000,China)

机构地区：[1]桂林理工大学土木工程学院广西岩土力学重点实验室,广西桂林541004 [2]中国地质大学工程学院,湖北武汉430000

出　　处：《河北工程大学学报（自然科学版）》2024年第5期27-35,共9页Journal of Hebei University of Engineering:Natural Science Edition

基　　金：国家自然科学基金资助项目(52169022)。

摘　　要：针对污染后膨胀土的力学特性问题,进行了无侧限抗压强度、直剪试验探讨宏观现象上力学特性的变化规律,结合电镜扫描试验分析微观结构上的变化规律,并在X射线衍射试验后,采用了JADE分析软件对所收集到的原始数据进行了定量物相分析,得出试样的各物相含量占比的变化趋势,以此来探讨膨胀土力学特性的变化机理。试验结果表明:在压实度与Mn^(2+)浓度相同的条件下,最优含水率的膨胀土试样强度最高;在初始含水率相同的条件下,试样的强度、内摩擦角和黏聚力均随着Mn^(2+)浓度的增大而呈现出增大的趋势;由JADE定量分析物相表明,受Mn^(2+)污染后土体内SiO_(2)呈现出增加的趋势。原因为MnSO_(4)溶液中的Mn^(2+)水解后间接导致了膨胀土试样中的硅酸盐类矿物也发生水解,释放了SiO_(2),增大了土体颗粒间的胶结作用,使得土体整体性、稳定性提高。In response to the mechanical characteristics of contaminated expansive soil,unconfined compressive strength and direct shear tests were conducted to explore the changes in mechanical characteristics at the macroscopic level,combining SEM experiments to analyze the changes in microstructure.After XRD experiments,JADE analysis software was used to quantitatively analyze the collected raw data and obtain the trend of changes in the proportion of each phase content in the sample,in order to explore the mecha-nism of changes in the mechanical properties of expansive soil.The experimental results show that under the same compaction degree and Mn^(2+)concentration,the expansive soil sample with the optimal moisture content has the highest strength;Under the same initial moisture content,the strength,internal friction angle,and cohesion of the sample all show an increasing trend with the increase of Mn^(2+)concentration;Quantitative analysis of the phase by JADE indicates that SiO_(2)in the soil shows an increasing trend after being contaminated with Mn^(2+).The reason is that the hydrolysis of Mn^(2+)in MnSO_(4)solution indirectly leads to the hydrolysis of silicate minerals in the expansive soil sample,releasing SiO_(2)and increasing the bonding effect between soil particles,thereby improving the overall integrity and stability of the soil.

关 键 词：膨胀土 锰离子 力学特性 应力-应变关系曲线 微观结构 

分 类 号：TU443[建筑科学—岩土工程]