ISSN 1000-3665 CN 11-2202/P

    冻融循环下含细粒盐渍化风积沙水盐迁移规律及强度特性

    Water-salt migration and strength characteristics of fine-grained salinized aeolian sand under freeze-thaw cycles

    • 摘要: 冻融作用会导致含细粒盐渍化风积沙工程性质发生显著劣化,从而使得风积沙路基长期服役性能下降,出现大量路基病害。为了研究冻融循环作用下细粒含量对盐渍化风积沙的水盐迁移规律及强度特性的影响,采用自行设计的冻融循环装置对不同细粒含量的盐渍化风积沙开展水盐迁移试验,并对冻融前后的土样进行系列直剪试验,得到了其在冻融循环作用下的温度场分布、水分盐分迁移以及强度劣化规律。试验结果表明:在冻融作用下,不同细粒含量盐渍化风积沙的温度均随时间呈波浪形变化趋势,且波动幅度随着土体深度的增加而减小;随着盐渍化风积沙中细粒含量的增加,土体所能达到的最低温度逐渐升高,土体中未冻水含量和总含水量逐渐降低,电导率峰值整体呈先降低后升高的趋势,含盐量不断增大;冻融前,不同垂直压力下盐渍化风积沙的抗剪强度随细粒含量的增加而增加,冻融后,各细粒含量盐渍化风积沙的抗剪强度均显著降低,并且细粒含量越高,其抗剪强度劣化越明显。该研究成果可为盐渍化风积沙地区道路建设提供理论指导。

       

      Abstract: Freeze-thaw cycles significantly deteriorate the engineering properties of fine-grained salinized aeolian sand, resulting in a decrease in the long-term performance of aeolian sand roadbeds and frequent roadbed diseases. To analyze the influence of fine content on the water-salt migration and strength characteristics of salinized aeolian sand at the edge of deserts under freeze-thaw cycles. A self-designed freeze-thaw cycle device was used to conduct water-salt migration tests on salinized aeolian sand with different fines content. A series of direct shear tests was conducted on soil samples before and after freeze-thaw cycles. The distribution of temperature field, the migration of water and salt, and the strength change before and after freeze-thaw cycles were obtained. The test results show that under the freeze-thaw condition, the temperature of salinized aeolian sand with different fines content showed a fluctuation with time, and the fluctuation amplitude decreased with the increase of depth. As fines content increased, the minimum soil temperature rose, while both unfrozen and total water contents decreased. The peak conductivity decreases and then increases, and the salt content continues to increase. Prior to freeze-thaw cycling, the shear strength of salinized aeolian sand under different vertical pressures increased with the increase of fines content, and after that, the shear strength of salinized aeolian sand with different fines content decreased significantly. The higher the fine content, the more obvious the deterioration of its shear strength. This study can provide theoretical guidance for road construction in salinized aeolian sand area.

       

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