冻融状态下粉质黏土电阻率、未冻水含量及温度关系  

Relationship between electrical resistivity,unfrozen water content and temperature of silty clay under freeze-thaw condition

作　　者：孙颜顶 刘波[2,3] 张静涛[1] 赵文科 田华良 占进军 雷亚伟 程霖 SUN Yanding;LIU Bo;ZHANG Jingtao;ZHAO Wenke;TIAN Hualiang;ZHAN Jinjun;LEI Yawei;CHENG Lin(China Construction Second Engineering Bureau Ltd.,Beijing 100160,China;School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国建筑第二工程局有限公司,北京100160 [2]中国矿业大学(北京)力学与建筑工程学院,北京100083 [3]中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室,北京100083

出　　处：《中国矿业大学学报》2023年第1期52-62,共11页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(42172319,41771083);中国建筑第二工程局有限公司科技计划项目(2022QN140001,91110000100024296D200003);中建股份科技研发计划项目(CSCEC-2021-Z-25)。

摘　　要：以冻结工程现场所取的粉质黏土为研究对象,监测了粉质黏土冻融过程中的电导率、未冻水体积分数、温度随时间的全过程变化,研究了粉质黏土的电阻率、未冻水含量及温度的关系,并提出了冻结粉质黏土电阻率模型,得到了其电阻率与未冻水体积分数(θ)的理论关系.试验研究表明:在粉质黏土冻结过程中,不同初始含水率的土样在相变点之前,土样的电导率随温度的阶梯变化而同步变化,在相变点之后,电导率随θ的变化而同步变化,土样相变点处的电导率、θ和温度都有明显的突变特征.土样在冻融过程中的电阻率和未冻水含量随温度的变化具有相似性,且都存在“滞后”现象.随着初始含水率的增加,土样冻结(或融化)过程中的电活化能整体呈增长趋势;土体在冻结过程中的电活化能明显大于融化过程中的电活化能,土体冻结和融化过程中的电活化能的变化可反映出电阻率的“滞后”现象,且土样冻结和融化过程中的电活化能的差值大小可反映电阻率的“滞后”程度.基于冻土电阻率模型,考虑孔隙水传导路径的曲折性和水分分布的不均匀性,并结合冻结温度位置后的粉质黏土的试验数据,得到了其电阻率与未冻水含量的关系方程.Taking the silty clay from the freezing engineering site as the research object,the change of electrical conductivity,volume unfrozen water content and temperature of silty clay with time during freezing and thawing were monitored.The relationship between electrical resistivity,volume unfrozen water content and temperature of silty clay was studied.The electrical resistivity model of frozen silty clay was put forward,and the theoretical relationship between electrical resistivity and volume unfrozen water content of soil was obtained.The experimental results show that during freezing the electrical conductivity of silty clay synchronously changes with change of temperature of soils before the phase transformation point,and after the phase transformation point synchronously changes with the change of volume unfrozen water content of soils.The electrical conductivity,volume unfrozen water content and temperature of soils at phase transformation point have obvious abrupt changes.The changes of electrical resistivity and unfrozen water content of soil samples with temperature are similar,and both of them have hysteresis phenomenon during freezing and thawing.With the increase of initial water content,the electrical activation energy of soils during freezing(or thawing)increases as a whole.The electrical activation energy of soils during freezing is significantly higher than that during thawing.The change of electrical activation energy between freezing process and thawing process can represent the hysteresis phenomenon of electrical resistivity.The difference of electrical activation energy of soil in the process of freezing and melting can reflect the hysteresis degree of resistivity.Based on the electrical resistivity model of frozen soil,the tortuosity of pore water conduction path,the non-uniformity of water distribution and the experimental data of silty clay after freezing temperature,the relationship equation between electrical resistivity of silty clay and unfrozen water content is derived.

关 键 词：冻土 电阻率 未冻水含量 温度 

分 类 号：TU411[建筑科学—岩土工程]