膨胀土强度干湿循环试验研究  

Experimental studies of strength of expansive soil in drying and wetting cycle

作　　者：吕海波[1,2] 曾召田[1,3] 赵艳林[1,2] 卢浩[3] 

机构地区：[1]广西大学土木建筑工程学院防灾减灾研究所,南宁530001 [2]桂林工学院土木工程系,桂林541004 [3]南宁铁路局科学技术研究所,柳州454007

出　　处：《岩土力学》2009年第12期3797-3802,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.40702053);广西科技攻关项目(桂科能0815011-6-4);广西水利厅科技专项(桂水科合字[2005]4号)

摘　　要：通过南宁地区原状膨胀土干湿循环试验,探讨了膨胀土抗剪强度与含水率、循环次数、循环幅度等循环控制参数的关系。研究结果表明:膨胀土抗剪强度随干湿循环次数增加而衰减,最终趋于稳定,强度稳定值与稳定时所需循环次数均随含水率变化幅度的增加而减小。在此基础上,利用压汞试验测定了膨胀土干湿循环过程中的孔径分布,发现干湿循环对土的粒间联结产生不可逆的削弱,使得土体形成更大的孔隙空间,在高含水率时主要表现为集聚体间孔体积增加,在低含水率时集聚体内孔体积增加,从而降低土的抗剪强度。Experimental studies were undertaken on an expansive soil from Nanning area in order to establish relationship between shear strength indices and cyclic drying and wetting parameters. It is shown that the shear strength of expansive soil decreases with increasing number of cycles and finally reaches to a constant state. The value and cyclic number of the constant state reduce with increase of amplitude of variation of water content. Furthermore, the mercury intrusion porosimetry （MIP） test was applied to determine the pore size distribution curve of expansive soil during wetting-drying cycle. The MIP test results show that the bond of soil is irreversibly damaged by cyclic drying and wetting, which leads to increase the volume of pore. In high water content, volume of outer-aggregate pores increase with number of cycles; while in low water content, volume of intra-aggregate pores will increase. As a result of degradation of microstructure, the shear strength of expansive soil quickly decreases.

关 键 词：膨胀土 抗剪强度 干湿循环 压汞试验 

分 类 号：TU443[建筑科学—岩土工程]