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张思钰, 张勇敢, 鲁洋, 刘斯宏. 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[J]. 岩土工程学报. DOI: 10.11779/CJGE20231279
引用本文: 张思钰, 张勇敢, 鲁洋, 刘斯宏. 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[J]. 岩土工程学报. DOI: 10.11779/CJGE20231279
Experimental study on freezing deformation characteristics of unsaturated expansive soil considering cyclic freeze-thaw and initial anisotropy[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20231279
Citation: Experimental study on freezing deformation characteristics of unsaturated expansive soil considering cyclic freeze-thaw and initial anisotropy[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20231279

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 soil considering cyclic freeze-thaw and initial anisotropy

  • 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。

     

    Abstract: The swelling and shrinkage deformation of expansive soils in seasonally frozen regions is significant, which seriously induces engineering hazards and disasters. To investigates the freezing-induced deformation characteristics of unsaturated expansive soil under the influence of cyclic freeze-thaw and initial anisotropy, a series of cyclic freeze-thaw tests and volumetric variation measurement tests of compacted expansive soils were carried out. The experimental results show that: (1) Compared with the melting state, the volumetric strain of expansive soil in freezing state is more significantly affected by 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 initial saturation, the frozen volumetric strain of expansive soil sample first decreases and then increases, it shows freezing shrinkage at low saturation and freezing swelling at high saturation. (3) There is a good quadratic relationship between frozen volumetric strain and water content, and there exists a characteristic value of "critical water content", at which the maximum volumetric shrinkage occurs. (4) Under cyclic freeze-thaw action, the frozen volumetric strain of the samples with low water content is more stable than the higher water content. The cumulative effect of axial strain with freezing times is more significant than that of 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 expansive soils in seasonally frozen regions.

     

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