考虑循环冻融历史与初始各向异性的非饱和膨胀土冻结变形特征试验研究  

Experimental study on freezing deformation characteristics of unsaturated expansive soils considering cyclic freeze-thaw and initial anisotropy

作　　者：张思钰 张勇敢 鲁洋[1,4] 刘斯宏[1,4] ZHANG Siyu;ZHANG Yonggan;LU Yang;LIU Sihong(College of Water Conservancy and Hydropower,Hohai University,Nanjing 210098,China;School of Human Settlements and Civil Engineering,Xi'an Jiaotong University,Xi'an 710049,China;School of Earth Sciences and Engineering,Hohai University,Nanjing 211100,China;International Joint Laboratory of Long-term Behaviour&Environmentally Friendly Rehabilitation Technologies on Dams,Hohai University,Nanjing 210098,China)

机构地区：[1]河海大学水利水电学院,江苏南京210098 [2]西安交通大学人居环境与建筑工程学院,陕西西安710049 [3]河海大学地球科学与工程学院,江苏南京211100 [4]河海大学大坝长效特性及环保修复技术中西联合实验室,江苏南京210098

出　　处：《岩土工程学报》2025年第5期1004-1013,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52109123,52279099)。

摘　　要：地处季冻区的膨胀土胀缩变形显著,由此诱发的工程隐患与灾害尤为严重。为探究循环冻融历史与初始各向异性影响下非饱和膨胀土的冻结变形特征,开展了压实膨胀土的循环冻融和体变量测试验。试验结果表明:①相较于融化状态,膨胀土在冻结状态下的体积应变受干密度与含水率影响更显著,含水率越高、干密度越大,试样融化和冻结状态下的体积应变差异越大。②膨胀土试样冻结体变随初始饱和度增加呈先减小后增大的变化趋势,且表现为低饱和度时“冻缩”,高饱和度时“冻胀”。③试样的冻结体积应变与含水率呈二次函数关系,存在一个“临界含水率”特征值,使得试样的体积收缩率最大。④循环冻融作用下,低含水率试样的冻结体积应变较高含水率时更易稳定;轴向应变随冻结次数的累积效应较径向应变更为显著。⑤压实作用诱导膨胀土试样冻结变形呈各向异性,且含水率越高,冻结变形各向异性越显著。研究结果可为季冻区膨胀土地段工程的变形控制和灾害防治提供参考。The swelling and shrinkage deformation of the expansive soils in seasonally frozen regions is significant,which seriously induces engineering hazards and disasters.To investigate the freezing-induced deformation characteristics of the unsaturated expansive soils under the influences of cyclic freeze-thaw and initial anisotropy,a series of cyclic freeze-thaw tests and volumetric variation measurement tests on the compacted expansive soils are carried out.The test results show that:(1)Compared with the melting state,the volumetric strain of the expansive soils in freezing state is more significantly affected by the dry density and water content.The higher the water content and dry density,the greater the difference of frozen and melted volumetric strains.(2)With the increase of the initial saturation,the frozen volumetric strain of the expansive soil samples first decreases and then increases,indicating freezing shrinkage at low saturation and freezing swelling at high saturation.(3)There is a good quadratic relationship between the frozen volumetric strain and the water content,and there exists a characteristic value of"critical water content",at which the maximum volumetric shrinkage occurs.(4)Under the cyclic freeze-thaw action,the frozen volumetric strain of the samples with low water content is more stable than that with the higher water content.The cumulative effects of the axial strain with freezing times are more significant than those of the radial strain.(5)The frozen deformation has compaction-induced anisotropy,which is more significant at higher water contents.The research results can provide reference for the deformation control and disaster prevention of the expansive soils in seasonally frozen regions.

关 键 词：膨胀土 冻融循环 冻结变形 各向异性 变形机理 

分 类 号：TU445[建筑科学—岩土工程]