冻融循环对固化铅污染土强度与孔隙特征影响的试验研究  

AN EXPERIMENTAL STUDY FOR INFLUENCE OF FREEZE-THAW CYCLES ON STRENGTH AND PORE CHARACTERISTICS OF SOLIDIFIED LEAD-CONTAMINATED SOIL

作　　者：杨忠平[1,2,3] 李登华 邓仁峰 田鑫 任书霈[1,2,3] YANG Zhongping;LI Denghua;DENG Renfeng;TIAN Xin;REN Shupei(Key Laboratory of New Technology for Construction of Cities in Mountain Area(Chongqing University),Ministry of Education, Chongqing 400045;School of Civil Engineering,Chongqing University,Chongqing 400045;National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas,Chongqing 400045;CMCE Engineering Co.,Ltd.,Chongqing 400039)

机构地区：[1]山地城镇建设与新技术教育部重点实验室(重庆大学),重庆400045 [2]重庆大学土木工程学院,重庆400045 [3]库区环境地质灾害防治国家地方联合工程研究中心,重庆400045 [4]中机中联工程有限公司,重庆400039

出　　处：《工程地质学报》2019年第3期539-549,共11页Journal of Engineering Geology

基　　金：国家自然科学基金(41772306)资助~~

摘　　要：水泥基固化剂封闭是近年来重金属污染修复治理的主要技术手段之一。冻融循环作用是影响水泥固化重金属污染土力学特性的重要外营力。本文以人工制备的铅污染土为研究对象,结合冻融实验和室内土工试验,研究冻融循环作用对铅污染土无侧限抗压强度的影响。结果表明:随着水泥掺量的增大,水泥固化铅污染土的无侧限抗压强度增大,破坏应变减小;随着铅离子掺量的增大(污染程度升高),水泥固化铅污染土的无侧限抗压强度q u降低,应力-应变曲线变化趋势更加相似;水泥固化铅污染土的无侧限抗压强度q u随冻融频次的增大而降低;相同冻融频次条件下,随着水泥掺量的增加,水泥固化铅污染土的无侧限抗压强度q u损失率降低。基于SEM图像对固化铅污染土进行微观结构定量分析,表明随着冻融次数的增加,试样中细颗粒(<1μm)和细孔隙(<2μm)所占比例均提高。冻融作用对土体结构的破坏可能是导致土样无侧限抗压强度q u降低的主要原因。Cement-based curing agent blocking is one of the main technology for the remediation of heavy metal contaminated soils in recent years.Freeze and thaw cycles(FTcs)is an important external agent affecting the mechanical properties of cement solidified heavy metal contaminated soil.In present study,the artificial lead-contaminated soil is prepared using a systematic design.FTcs tests and laboratory soil tests are employed to reveal the influence of freeze and thaw cycle on the unconfined compression strength of lead-contaminated soil.The results show that:with the increasing of the proportion of cement,the unconfined compression strength(q u)of cement solidified lead-contaminated soil increases,while failure strain decreases.With the increasing of the proportion of lead ion(higher pollution level),the unconfined compression strength(q u)of cement solidified lead-contaminated soil decreases.However,the trend of stress-strain curves is similar.The unconfined compressive strength of cement solidified lead-contaminated soil decreases with the increasing of freeze-thaw times.When the freeze-thaw times is the same,the loss rate of unconfined compressive strength of cement solidified lead-contaminated soil decreases with the increasing of the proportion of cement.The microstructure of solidified lead contaminated soil is quantitatively analyzed using SEM image.It is found that the proportion of fine particles(<1μm)and fine pores(<2μm)in the samples increases with the increasing of freeze-thaw times.It may be the main reasons leading to the decreasing of unconfined compressive strength of the soil that failure of freeze and thaw cycles on soil structure.

关 键 词：冻融循环 水泥固化铅污染土 无侧限抗压强度 孔隙特征 SEM 

分 类 号：X53[环境科学与工程—环境工程]