原状膨胀土裂隙演变性状的环境效应与表征  

Environmental effect and characterization of crack evolution in undisturbed expansive soils

作　　者：周振华 孔令伟[1,2] 李甜果 舒荣军 ZHOU Zhen-hua;KONG Ling-wei;LI Tian-guo;SHU Rong-jun(State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Civil and Architecture Engineering,Chuzhou University,Chuzhou,Anhui 239000,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程安全全国重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]滁州学院土木与建筑工程学院,安徽滁州239000

出　　处：《岩土力学》2025年第2期402-412,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.42402290);国家重点研发计划项目(No.2019YFC1509901)。

摘　　要：为探究原状膨胀土裂隙演变性状的环境效应,利用环境箱对饱和原状膨胀土开展不同湿度环境下的脱湿试验,并结合计算机断层扫描(computed tomography,简称CT)技术提取土体裂隙网络,计算相关特征指标。结果表明:膨胀土裂隙演变性状可由特征指标定量表征,且各项指标与脱湿速率密切相关;脱湿速率的提升逐渐弱化了土体的收缩变形程度,且二维裂隙率沿高度方向上的分布呈现出显著变化;从三维角度看,脱湿导致微裂隙持续扩张,且渐增的脱湿速率使得孔隙间的连通性不断增强,具体表现在土体连通裂隙率、孔隙与喉道体积、平均配位数的不断增长;另外,随着脱湿速率的增长,裂隙分布可概化为三阶段演变模式:(1)水平裂隙逐渐连通,斜向裂隙逐渐增多;(2)水平裂隙的连通度达到最大,斜向裂隙占比达到峰值;(3)斜向裂隙逐渐连通,水平裂隙再次衍生。裂隙分布演变模式最主要取决于原生裂隙的初始分布状态,而脱湿速率则是影响裂隙规模及连通程度的重要因素。To explore the environmental effect of crack evolution characteristics of expansive soils,an environmental chamber was employed to perform desiccating tests on saturated undisturbed expansive soils in varying humidity environments.The soil crack network was extracted using computed tomography(CT)to obtain relevant characteristic indexes.The results show that crack evolution characteristics of expansive soils can be quantitatively characterized by characteristic indexes,which are closely related to desiccating rate.An increased desiccating rate reduces soil shrinkage strain and causes significant fluctuations in the two-dimensional longitudinal porosity.From a 3D perspective,water loss causes the gradual extension of micro-scale cracks.An increased desiccating rate results in greater connected porosity,pore-throat volume,and average coordination number,indicating enhanced connectivity between pores.Most cracks in expansive soil are distributed horizontally.As the desiccating rate increases,cracks exhibit a three-stage distribution pattern:(i)horizontal cracks progressively connect,and oblique cracks gradually increase;(ii)the connectivity of horizontal cracks reaches its maximum,and the proportion of oblique cracks peaks;(iii)oblique cracks gradually connect,and horizontal cracks re-emerge.The evolution pattern of crack distribution mainly depends on the initial distribution state of primary cracks,with the desiccating rate being an important factor affecting crack scale and connectivity degree.

关 键 词：原状膨胀土 湿度环境 裂隙演变性状 表征 连通性 

分 类 号：TU443[建筑科学—岩土工程]