人工冻结作用下原状软黏土冻融特性试验  

Experimental study on freeze⁃thaw characteristics of undisturbed soft clay under artificial freezing

作　　者：王升福 樊文虎 戴道文 薛凯喜[1] 李栋伟 WANG Shengfu;FAN Wenhu;DAI Daowen;XUE Kaixi;LI Dongwei(East China University of Technology,Nanchang 330013,China;Nanjing Forestry University,Nanjing 210037,China)

机构地区：[1]东华理工大学土木与建筑工程学院,南昌330013 [2]南京林业大学土木工程学院,南京210037

出　　处：《林业工程学报》2020年第4期154-160,共7页Journal of Forestry Engineering

基　　金：国家自然科学基金(51478226,51869001,41977236);江西省教育厅科技计划项目(GJJ170485)。

摘　　要：近年来人工冻结法在地铁联络通道施工等地下工程加固中得到广泛应用,土体经过冻融后物理力学性质和工程性质将发生改变。通过不同冷端温度冻结条件下封闭系统原状土单向冻融试验,研究软黏土冻胀融沉特性。结合冻融过程温度场监测,获得温度、冻结锋面的发展规律,对冻融后的试样分层进行含水率、孔隙率及干密度的测定,得到软黏土冻融后水分重分布及体积变化特征。试验结果表明:封闭系统4种不同冷端温度冻结土样的融沉系数均大于冻胀率,冻结完成时沿试样不同高度处温度梯度呈线性分布。冻结过程冻结锋面发展与时间呈指数关系,冻结完成时间与冻结冷端温度呈指数关系。冻融后沿试样高度方向水分重分布,试样上部含水率减小,中下部增大,且冻结冷端温度越低,变化越明显。结合沿土样高度不同位置处含水率、孔隙比和干密度的变化,揭示了冻融过程随水分迁移过程负孔压的存在对土样有固结作用。The artificial ground freezing method has been widely used in the reinforcement of underground engineering,including the cross passage construction of metro,etc.The physical,mechanical and engineering properties of soil are changed after freezing-thawing.In order to study the freeze-thaw characteristics of undisturbed soft clay under artificial freezing,a series of laboratory tests were carried out in this study.The frost heave and thaw settlement characteristics of soft clay were studied by unidirectional freeze-thaw tests of undisturbed soil in a closed system at different cold end temperatures.Combining with the monitoring of temperature field in the freezing-thawing process,the development law of temperature and freezing front was obtained.The moisture content,porosity and dry density of tested samples after freeze-thaw were measured,and the water redistribution and volume change characteristics of soft clay after freeze-thaw were obtained.The experimental results show that the thaw settlement coefficients of four frozen soil samples at different cold-end temperatures in the closed system are larger than the frost heave ratios.The temperature gradient shows a linear distribution along the different height of tested sample when the freezing is completed.There is an exponential relationship between the freezing completion time and the freezing end temperature.After freezing and thawing,the moisture redistribution along the height of tested sample decreases in the upper part and increases in the middle and lower parts,and the moisture change becomes more obvious at the lower freezing cold end temperature.Combined with the changes of moisture content,void ratio and dry density at different locations along the height of soil sample,it is revealed that the existence of negative pore pressure in the freeze-thaw process has a consolidation effect on soil sample.The test results also showed that the temperature field of soft clay and the physical and mechanical properties of the soil,including moisture content,void ra

关 键 词：软黏土 人工单向冻融 冻融特性 水分重分布 

分 类 号：TU445[建筑科学—岩土工程]