干湿循环对黏土微观结构及持水性能影响的试验研究  

Experimental study on influences of wetting-drying cycles on microstructure and water-retention characteristics of clay

作　　者：杨旭[1] 蔡国庆[1,2] 刘倩倩 李风增 单冶鹏 YANG Xu;CAI Guoqing;LIU Qianqian;LI Fengzeng;SHAN Yepeng(Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;Zhengzhou Highway Development Centre,Zhengzhou 450015,China)

机构地区：[1]城市地下工程教育部重点实验室,北京100044 [2]北京交通大学土木建筑工程学院,北京100044 [3]郑州市公路事业发展中心,河南郑州450015

出　　处：《岩土工程学报》2024年第S02期11-15,共5页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(U2034204,52078031);中央高校基本科研业务费项目(2023JBZD004)。

摘　　要：长期干湿循环作用会削弱路基土的工程力学性质,产生工程灾害,有必要研究干湿循环对其微观结构及持水性能的影响。针对既有线有砟轨道路基土,开展了一系列考虑干湿循环影响的压汞试验、扫描电镜试验、压力板试验与饱和盐溶液蒸汽平衡试验。试验结果表明:在反复的干湿循环过程中,土体结构遭到破坏,内部胶结物质不断减少。土体微孔及小孔(<5μm)数量逐渐增多,中孔及部分大孔范围(5~30μm)内的峰值孔径逐渐减小,分布密度逐渐增大。数次干湿循环后微裂隙(>100μm)逐渐增多,导致试样开裂。干湿循环会对土体的持水性能产生影响,初始干密度较小时,经历过1次干湿循环持水性能略有增强,而经历过3次及5次干湿循环持水性能持续减弱。The Long-term wetting-drying cycles can weaken the engineering characteristics of subgrade fillers,resulting in engineering disasters.It is necessary to study the effects of the wetting-drying cycles on their microstructure and water-retention performance.A series of mercury intrusion tests,scanning electron microscopy tests,pressure plate tests and saturated salt solution vapor equilibrium tests considering the influences of the wetting-drying cycles are carried out on the subgrade filler of the existing ballasted track roads.The experimental results show that during repeated wetting-drying cycles,the soil structure is damaged,and the internal cementitious materials are continuously reduced.The number of micropores and small pores(<5μm)in the soil gradually increases,while the peak pore size in the range of mesopores and some large pores(5~30μm)gradually decreases,and the distribution density gradually increases.After several wetting-drying cycles,the number of microcracks(>100μm)gradually increases,leading to cracking of the soil specimens.The wetting-drying cycles have effects on the water-retention characteristics of the soil.When the initial dry density is low,the air-entry value after experiencing one wetting-drying cycle is slightly higher than that without wetting-drying cycles,while the air-entry value of the specimen after three and five wetting-drying cycles continues to decrease.

关 键 词：干湿循环 有砟铁路黏土填料 微观结构 持水性能 

分 类 号：TU442[建筑科学—岩土工程]