通过给冻土单桩模型上端施加循环荷载,分析循环荷载幅值、频率及冻土温度的变化对桩身应变、桩身轴力、桩侧冻结应力以及桩土相对位移的影响规律,开展循环荷载作用下冻土桩基力学特性的研究.研究结果表明:桩身应变随着加载时间先增加后稳定,且低温环境和小荷载条件下更有利于桩身应变的稳定;桩身的应变随荷载幅值及频率的增加而变大,随温度的降低而减小;桩身轴力沿着桩深不断减小,是由于桩侧土体使桩从上部开始受力;低温环境下桩身轴力相对较小,这是冻土地区桩基稳定的有利条件;桩侧冻结应力首先从桩基的上端发挥作用,并逐渐向下传递,分别增大荷载幅值、频率及降低温度都会增强桩侧冻结应力;桩土相对位移受荷载幅值、频率及温度的影响明显,频率能够影响桩土的承载模式.%By applying cyclic loading on frozen soil model of single pile, this test analyzed the influence of the size and frequency of the cycle loading and temperature on the strain of pile, pile side freezing stress, axial force of pile and relative displacement of piles and soil. The mechanical properties of frozen soil pile foundation under cyclic loading were then studied. The results show that pile strain increases initially and becomes stable eventually with the loading time. The pile strain needs less time to stabilize under low temperature environment or small load. The strain of pile gets bigger along with the increase of load amplitude, while it decreases with the decrease of temperature and becomes larger with the increase of frequency. Pile side freezing stress acts on the pile from the top of the pile foundation and gradually passing down, increasing of load amplitude and frequency or decreasing of temperature will increase pile side freezing stress. Pile axial force gradually becomes smaller along the pile depth, because the effect acts begin from the top. The axial force of pile decreases when temperature is smaller. The relative displacement of piles and soil changes significantly under the influence of load amplitude, and frequency and temperature, and frequency can affect the bearing model of pile soil.
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