阴离子聚丙烯酰胺改性压实黄土的力学特性研究  

Mechanical properties of compacted loess modified by anionic polyacrylamide

作　　者：周伟洋 刘建坤 南霁云 ZHOU Weiyang;LIU Jiankun;NAN Jiyun(School of Civil Engineering,Sun Yat-sen University,Zhuhai 519082,China)

机构地区：[1]中山大学土木工程学院,广东珠海519082

出　　处：《人民长江》2022年第8期159-166,共8页Yangtze River

基　　金：国家自然科学基金项目(41731281);国家重点基础研究发展计划项目(2012CB026104);珠海市科技计划项目(ZH22036204200009PWC)。

摘　　要：阴离子聚丙烯酰胺(APAM)常作为农业领域的土壤改良剂,关于其改性土体工程力学性能的研究则很少。通过击实、土壤浸出液导电率、无侧限抗压强度和固结试验,并加入无水氯化钙(CaCl_(2))作为补充钙源,对APAM改性压实黄土进行了工程力学性能评价。试验结果表明:只加APAM能使土体最大干密度(ρ_(dmax))较对照组增大2.19%~3.77%,无侧限抗压强度(q_(u))增幅为43.3%~61.2%;同时加入APAM和CaCl_(2)能进一步提升改性土的力学性能,q_(u)的增幅达85.3%;导电率试验证明了APAM能增强土体的胶结作用。通过扫描电镜(SEM)能观察到改性土有更大的土团聚体和更小的孔隙,其成因是改良剂和压实功的双重效应使土体的胶结作用增强。掺入APAM能提升湿陷性黄土的力学性能,但改良存在施用阈值,0.03%是一个相对合适的掺入比。同时掺入APAM和CaCl_(2)对土体的改良效果优于单独掺入APAM或CaCl_(2)。Anionic polyacrylamide(APAM)is often used as soil ameliorant agent in agricultural field,but there are few studies on its application in engineering mechanical performance.By conducting experiments including compaction,conductivity of soil leaching solution,unconfined compressive strength and consolidation tests,and adding anhydrous calcium chloride(CaCl_(2))as supplemental calcium source,the engineering performance of APAM modifying compacted loess was evaluated.Results indicate that loess modified with single APAM exhibits improvement in the maximum dry density(ρ_(dmax))by 2.19%-3.77%,and in the unconfined compressive strength(q_(u))by 43.3%-61.2%compared with the control group.The mechanical properties of the modified soil can be further improved by adding APAM and CaCl_(2) simultaneously,with the increase of q_(u) up to 85.3%.The results of conductivity test indicate that APAM can enhance soil cementation.It can be observed by scanning electron microscopy(SEM)that the modified soil has larger soil aggregates and smaller pores,which is formed by the dual effects of modifier and compaction effort that enhance the cementation of the soil.The mechanical properties of collapsible loess can be improved by adding APAM,but an application threshold exists in the improvement,and 0.03%is a relatively appropriate incorporation ratio.The improvement effect of adding APAM and CaCl_(2) simultaneously is better than that of adding APAM or CaCl_(2) only.

关 键 词：湿陷性黄土改良 力学特性 阴离子聚丙烯酰胺 无水氯化钙 施用阈值 

分 类 号：TU444[建筑科学—岩土工程]