The warming and melting of permafrost due to climate warming pose a considerable threat to the integrity of the Pan Arctic building, thus jeopardizing sustainable development. The increase in ambient temperature in permafrost areas will cause deterioration in the bearing capacity of building pile foundations. Considering the continuous deepening of the active layer (z), the present paper used small-scale physical modeling to investigate the potential variation of bearing capacity and load transfer mechanism of pile foundations under the scenario of continuous degradation of permafrost. The ultimate bearing capacity of a single pile and the undrained shear strength of the ground under different z are estimated by cone penetration tests. In the static load test of single piles, the axial load-settlement, axial force of pile shaft, and earth pressure at the pile tip are measured. The results show that the rise in ground temperature and the deepening of the z shorten the elastic and elastic-plastic stages of the load-displacement curve, resulting in a gradual decline in the bearing capacity of a single pile. The pile-soil interface temperature is always higher than the adjacent ground temperature at the same depth. Adfreezing force of the pile-soil interface decreases due to the increase in ground temperature and water content. With the deepening of z, the peak point of the shaft resistance decreases from −30 cm to −60 cm under the ultimate state. Meanwhile, with more axial load transfer along the pile shaft to the pile tip, the share ratio of pile tip resistance to ultimate stress gradually increases. In addition, the temperature rise of frozen soil at the pile tip accelerates the settling rate of the pile, which eventually causes the pile foundation failure.

中文翻译：

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多年冻土退化过程中建筑桩基承载力演化研究

气候变暖导致的永久冻土变暖和融化对泛北极建筑的完整性构成相当大的威胁，从而危及可持续发展。多年冻土地区环境温度升高会导致建筑桩基承载力恶化。考虑到活动层（z）的不断加深，本文采用小尺度物理模型研究了多年冻土持续退化情景下桩基承载力和荷载传递机制的潜在变化。通过贯入试验估算了不同z值下单桩的极限承载力和地面不排水抗剪强度。单桩静载试验中，测量轴力沉降、桩身轴力和桩端土压力。结果表明，地温升高和z加深使荷载-位移曲线的弹性阶段和弹塑性阶段缩短，导致单桩承载力逐渐下降。桩-土界面温度始终高于同一深度的邻近地层温度。由于地温和含水量的增加，桩土界面的冻结力减小。随着z的加深，极限状态下轴阻峰值点从-30 cm减小到-60 cm。同时，随着更多的轴向荷载沿桩身传递至桩端，桩端阻力对极限应力的份额逐渐增大。另外，桩端冻土温度升高，加速了桩的沉降速度，最终导致桩基破坏。