原状膨胀土干湿过程中持水特性及孔隙结构分析  

Water Retention Behavior and Pore Structure Analysis of Undisturbed Expansive Soil During Drying and Wetting

作　　者：何芳婵[1,2] 张俊然 HE Fangchan;ZHANG Junran(School of Water Conservancy Engineering,Zhengzhou University,Zhengzhou 450001,China;Henan Keda Water Conservancy Survey and Design Co.,Ltd.,Zhengzhou 450003,China;Henan Province Key Laboratory of Geomechanics and Structural Engineering,North China University of Water Resources and Electric Power,Zhengzhou 450046,China)

机构地区：[1]郑州大学水利科学与工程学院,河南郑州450001 [2]河南省科达水利勘测设计有限公司,河南郑州450003 [3]华北水利水电大学河南省岩土力学与水工结构重点实验室,河南郑州450046

出　　处：《应用基础与工程科学学报》2022年第3期736-747,共12页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(41602295);河南省高等学校重点科研项目(21A410002);河南省高等学校青年骨干教师培养计划项目(2020GGJS-094)。

摘　　要：国内外学者对重塑膨胀土的持水特性和孔隙结构研究较多,但对干湿过程中原状膨胀土的持水特性和孔隙结构研究较少.运用WP4C仪量测原状与重塑膨胀土在脱湿与吸湿过程中的土水特征曲线,同时用压汞法量测脱湿到不同吸力时原状和重塑膨胀土的孔隙结构.试验结果表明:原状与重塑膨胀土的土水特征曲线均有明显的滞回特性,但原状膨胀土的滞回圈比重塑试样的要大.原状土的累计汞压入体积量曲线高于重塑土的,两者曲线变化特征一致;随着含水率的减小累积分布曲线整体向下移动.关于孔径分布曲线,原状样的孔隙分布曲线为单峰,但干化后原状样的曲线上单峰逐渐消失;干化后的原状土和重塑土的曲线具有相似性,颗粒间孔隙在0.1~0.01μm间均存在峰值,但积聚体内孔隙所对应的峰值存在差异;原状膨胀土的曲线波动幅度和频率较重塑膨胀土的大,且原状土的分布曲线具有明显的锯齿状,从而导致原状土具有更明显的瓶颈效应,这可解释原状样的滞回圈比重塑样大的现象.Many scholars have studied the water retention characteristics and pore structure of remolded expansive soils,but few studies on the water retention characteristics and pore structure of undisturbed expansive soils during drying and wetting.Soil-Water Characteristic Curves(SWCCs)of undisturbed and remolded expansive soil specimens were measured by WP4C apparatus during drying and wetting,and the pore size distribution of undisturbed and remolded expansive soil specimens were measured by mercury intrusion pressure(MIP)method at different suctions during drying process.The results show that the SWCCs of expansive soil specimens have obvious hysteresis,but the hysteresis loop of undisturbed expansive soil is larger than that of remolded soil.The cumulative mercury injection volume curve of undisturbed soil was significantly higher than that of remolded soil.The cumulative distribution curve moves down as a whole with decreasing water content.The pore distribution of the undisturbed specimen was a single-peak pore structure,and the single-peak curve gradually disappeared after drying.The pore size distribution curves of undisturbed soil after drying and remolded soil are similar,there is peak values between 0.1μm and 0.01μm in intergranular pores,but the corresponding peak values of intra-aggregate are different.The curve fluctuation amplitude and frequency of undisturbed specimen is larger than that of remolded specimen,and so the distribution curve of undisturbed expansive soil has obvious jagged shape,which leads to more obvious bottleneck effect of undisturbed soil,thus explaining the phenomenon that the hysteresis loop of undisturbed specimen is larger than that of remolded specimen.

关 键 词：原状膨胀土 干湿过程 孔隙结构 土水特征曲线 WP4C 滞回圈 孔径分布 

分 类 号：TU45[建筑科学—岩土工程]