红黏土失水收缩孔隙演化及微观机理分析  

Analysis on Pore Evolution and Microscopic Mechanism of Red Clay during Loss Water and Shrinkage

作　　者：张亚彬 左双英[1] 李雨霏 黄殷婷 莫云川 Zhang Yabin;Zuo Shuangying;Li Yufei;Huang Yinting;Mo Yunchuan(College of Resources and Environment Engineering,Guizhou University,Guiyang,550025,P.R.China)

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025

出　　处：《地下空间与工程学报》2022年第6期1882-1890,共9页Chinese Journal of Underground Space and Engineering

基　　金：贵州省科学技术厅社会发展科技攻关项目(黔科合支撑[2017]2866);贵州省科学技术基金(黔科合基础[2020]1Z052)。

摘　　要：为揭示贵阳红黏土常温失水过程中孔隙演化规律及收缩机制,对红黏土进行收缩试验、压汞试验和X射线衍射试验,并采用晶层渗透压理论和毛细管理论解释其微观机理。研究结果表明,含水率对红黏土收缩有促进作用,且收缩具有各向异性特征。当红黏土收缩时,主要经历3个阶段:第1阶段,正常收缩阶段,团聚体间大孔、中孔,随着含水率的不断减小体积逐步减小,同时产生越来越多的小孔、微孔;第2阶段,残余收缩阶段,在团聚体内部,大量的小孔变为微孔;第3阶段,零收缩阶段,不管是团聚体间还是团聚体内,所有孔隙都保持不变。红黏土蒙脱石矿物含量较高,其晶层内外存在的渗透压差使水分子向孔隙液中迁移导致晶层间距减小,宏观上表现为土体收缩。通过Kelvin毛细管理论,建立了贵阳红黏土各收缩阶段饱和度与吸力之间的关系,解释了基质吸力对收缩过程控制的内在机理。In order to reveal the pore evolution law and shrinkage mechanism of Guiyang red clay in the process of water loss at room temperature, shrinkage test, mercury intrusion porosimetry test and X-ray diffraction test were carried out on the red clay. Crystal layer osmotic pressure theory and capillary theory were adopted to explain its microscopic mechanism. The study results show that: the water content promotes the shrinkage of the red clay, and the shrinkage was anisotropic. The shrinkage goes through three main stages: First, the normal shrinking stage, when the volume of the pores, no matter macro-or meso-, between the aggregates decreases and more and more small pores and micropores appear with the gradual reduction of water content;second, the residual shrinkage stage, when a large number of small pores become micropores within the aggregates;third, the zero shrinkage stage, when all pores remain constant within and between the aggregates. The red clay is high in montmorillonite, and the osmotic pressure difference between the inside and outside of its crystal layer causes the migration of water molecules into the pore, leading to the narrow of the distance between the crystal layers, which macroscopically manifests as soil shrinkage. Through Kelvin capillary theory, we established the relationship between the saturation and the suction of Guiyang red clay at each shrinkage stage, and explained the internal mechanism of controlling of the matrix suction to the shrinkage process.

关 键 词：红黏土 原状样 收缩 孔隙分布 微观试验 

分 类 号：TU41[建筑科学—岩土工程]