冻融循环对含盐土物理力学性质影响的试验研究

Influence of freeze-thaw cycles on physical and mechanical properties of salty soil

单轴抗压强度是岩土的重要力学性质之一,同时也是寒区工程建设中基础设计的一个重要依据。为研究冻融循环作用对含盐土单轴抗压强度的影响,以兰州黄土为研究对象,其中添加无水硫酸钠,对不同含盐量和含水率的试样在经历不同的冻融循环次数后,在常温下测试其单轴抗压强度试验。试验揭示了含盐土在常温下的应力应变曲线呈明显的脆性破坏,而经冻融的试样未出现明显的屈服阶段直到达到极限应力而进入弱塑性破坏;分析了硫酸钠盐在土体冻融循环中对土体强度的强化和弱化两种作用;得出了含硫酸钠盐黄土经历冻融循环达到新动态平衡的次数为6次。

The uniaxial compressive strength is one of the main mechanical properties of soil, and it is also an important criterion for the foundation design in cold region engineering of 58 samples. Lanzhou loess are prepared with different water contents and salt contents for exposure to a maximum of 10 closed-system freeze-thaw cycles in order to study the influence of cyclic freeze-thaw on physical and mechanical properties of salty soil, especially the uniaxial compressive strength at room temperature. The experiments indicate the way of the failure of the salty soil is brittle fracture obviously from the relationship of stress-strain, though the salty soil with freeze-thaw cycles has no yielding phase, and it has plastic failure after it reaches the ultimate stress. And the strength of the salty soil is strengthened and weakened due to the mix of the sodium sulfate; and to get a new dynamic equilibrium of the loess with sodium sulfate, the required freeze-thaw cycles are 6.