冻融循环下固化土静动力学特性试验研究

    Experimental study on static and dynamic characteristics of solidified soil under freeze-thaw cycles

    • 摘要: 固化土在季冻区受冻融和循环荷载影响,其力学特性会发生劣化,导致承载性能降低。本文通过开展冻融循环下静和动三轴试验,系统分析了固化淤泥质土在不同冻融循环次数、冻结温度及解冻条件下的静动力学指标衰减规律,并结合微观电镜扫描试验,揭示了固化土冻融循环条件下结构损伤机理。结果表明:随着冻融循环次数增加和冻结温度降低,固化土割线模量最大衰减幅度为30.0%,强度最大衰减幅度为35.4%。动荷载作用下,累积应变曲线可分为稳定型与破坏型,临界动强度随冻融次数增多和冻结温度降低而减小,最大降幅为33.1%;微观试验结果表明冻融作用会导致土体孔隙增多、增大,颗粒联结弱化,而循环动荷载则使土体结构重组、孔隙压缩。

       

      Abstract: In seasonally frozen regions, solidified soil is affected by freeze-thaw cycles and cyclic loads, leading to the deterioration of its mechanical properties and a reduction in bearing capacity. In this study, static and dynamic triaxial tests under freeze-thaw cycles are conducted to systematically analyze the attenuation behaviors of static and dynamic mechanical indices of solidified mucky soil under different freeze-thaw cycles, freezing temperatures, and thawing conditions. Combined with scanning electron microscope (SEM) tests, the structural damage mechanism of solidified soil under freeze-thaw cycles is revealed. The results show that with the increase of freeze-thaw cycles and the decrease of freezing temperature, the maximum attenuation rate of the secant modulus of solidified soil reaches 30.0%, and the maximum attenuation rate of strength is 35.4%. Under dynamic loads, the cumulative strain curves can be divided into two types: stable and failure modes. The critical dynamic strength decreases with increasing number of freeze-thaw cycles and decreasing freezing temperature, with a maximum reduction of 33.1%. Microscopic test results indicate that freeze-thaw action leads to an increase in the number and size of pores in the soil and weakens particle bonding, while cyclic dynamic loads cause soil structure reorganization and pore compression.

       

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