水分迁移对冻土细观结构的影响  

Impact of water migration on meso-structure of frozen soil

作　　者：明锋[1] 李东庆[1] 陈世杰[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,甘肃兰州730000

出　　处：《冰川冻土》2016年第3期671-678,共8页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(41271080);冻土工程国家重点实验室项目(SKLFSE-ZQ-35);国家重点基础研究发展计划项目(2012CB026102)资助

摘　　要：冻结作用导致土体中产生了水分迁移,从而改变了土体密度,进而改变了土体结构性及其物理力学性质.利用CT设备,对冻融前后的土样进行CT细观试验,通过CT数变化定量分析土样的损伤程度,反映冻土结构的变化.结果表明:冻结过程中同时发生了裂纹的张开与闭合,冰透镜体位置裂纹数量在冻结后明显增加.冻结区土样在水分迁移并结晶的作用下被切割成多个多边形,造成土样孔隙增大,导致CT数减小,损伤量增大.融土区土体在冻胀力作用下产生了一定的固结,使得其密度增大,CT数增大,损伤量表现为负值.上部荷载对土体损伤有抑制作用,而冻融作用却加剧了土体损伤.Structural change of soil due to freezing- thawing is the main cause of the variation of physical- mechanical properties of soil. In this paper,a frost-susceptible soil was taken as the research object for investigating the structural change induced by the redistribution of water. The CT scanning of soil before and after the unidirectional freezing tests was carried out for quantitative analysis of the change in soil structure. The result shows that CT scanning has been demonstrated to be successful in monitoring water migration within the frozen soil specimens. The preliminary results indicate that the freezing process causes water migration,resulting in change in density of the soil specimen. The cracks are opening or closing in the freezing process and the number of cracks around the ice lens increase after freezing. CT can produce clear images show ing the ice lens distribution within a frozen soil and the CT number can reflect the amount of water migration,as well as the consolidation of soil between the ice lenses. With the effect of frost heaving force,the unfrozen soil will be compacted and CT number will increased,so the damage amount is negative. The upper load will restrain soil damage,whereas freezingthawing will intensify soil damage.

关 键 词：冻土 水分迁移 细观结构 CT扫描 

分 类 号：TH774[机械工程—仪器科学与技术] P642.14[机械工程—精密仪器及机械]