邱恩喜, 潘宏宇, 何巧玲, 等. 2024. 冻融条件下冰碛土力学特性试验及模型研究[J]. 工程地质学报, 32(3): 772-784. doi: 10.13544/j.cnki.jeg.2023-0351.
    引用本文: 邱恩喜, 潘宏宇, 何巧玲, 等. 2024. 冻融条件下冰碛土力学特性试验及模型研究[J]. 工程地质学报, 32(3): 772-784. doi: 10.13544/j.cnki.jeg.2023-0351.
    Qiu Enxi, Pan Hongyu, He Qiaoling, et al. 2024. Tests on the mechanical properties of moraine soils under freeze-thaw conditions and the modified Duncan-Zhang model[J]. Journal of Engineering Geology, 32(3): 772-784. doi: 10.13544/j.cnki.jeg.2023-0351.
    Citation: Qiu Enxi, Pan Hongyu, He Qiaoling, et al. 2024. Tests on the mechanical properties of moraine soils under freeze-thaw conditions and the modified Duncan-Zhang model[J]. Journal of Engineering Geology, 32(3): 772-784. doi: 10.13544/j.cnki.jeg.2023-0351.

    冻融条件下冰碛土力学特性试验及模型研究

    TESTS ON THE MECHANICAL PROPERTIES OF MORAINE SOILS UNDER FREEZE-THAW CONDITIONS AND THE MODIFIED DUNCAN-ZHANG MODEL

    • 摘要: 青藏高原地区的冰碛土多处于季节性冻土区,而冰碛土在冻融循环作用下,容易引发地质灾害和影响工程建设,因此研究冻融循环作用后冰碛土力学性质和强度劣化对该区域工程的安全建设有重大的意义。对藏东南地区冰碛土开展冻融循环后的三轴压缩试验,并采用邓肯-张模型及修正邓肯-张模型对冻融后冰碛土的适用性进行验证,同时探讨了模型参数与冻融循环次数的关系。结果表明:(1)高围压下,冻融后试样表现出更明显的应变软化现象;(2)冻融循环次数与土体内摩擦角无显著相关性,而黏聚力呈负指数型函数衰减,这与直剪试验结果一致;(3)采用邓肯-张模型预测冻融作用下冰碛土的应力-应变曲线,低围压下模拟精度较高,模型参数K和冻融循环次数呈负指数函数关系;(4)修正邓肯-张模型可以较好反映试样的应变软化特性,但对于试样破坏后的残余强度阶段,理论值与试验结果相差很大,可靠度低。该研究以期为寒区工程建设提供基础性参考。

       

      Abstract: Moraine soils in the Tibetan Plateau region are prone to causing geological disasters and threatening engineering construction under the influence of freezing and thawing. Therefore, this paper conducts triaxial compression tests and employs the Duncan-Zhang and modified Duncan-Zhang models to study the mechanical properties and strength deterioration of moraine soils. The results show that: (1)under high confining pressure, the specimen after freezing and thawing exhibits a more pronounced strain-softening phenomenon; (2)the number of freezing and thawing cycles has no significant correlation with the friction angle in the soil body, and the cohesion follows a negative exponential function of attenuation; (3)the Duncan-Zhang model is utilized to predict the stress-strain curve of moraine soils under freezing and thawing, and the simulation accuracy is higher under low confining pressure. The model parameters and the number of freezing and thawing cycles exhibit a negative exponential function relationship; (4)the modified Duncan-Zhang model can be employed to adjust the Duncan-Zhang model. The modified Duncan-Zhang model better reflects the strain-softening characteristics of the specimen. However, for the residual strength stage after the destruction of the specimen, the theoretical value significantly differs from the experimental results, and the reliability is low. This study aims to provide a fundamental reference for engineering construction in cold regions.

       

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