Monitoring and simulation of the thermal behavior of cast-in-place pile group foundations in permafrost regions

Abstract

The heat emitted in the construction process of cast-in-place (CIP) pile foundations and the subsequent cement hydration process cause a thermal disturbance in the surrounding permafrost and reduce the early load capacity. In this paper, based on monitoring and simulation, the thermal behavior of CIP pile groups in permafrost regions was analyzed. The results indicate that the overlapping thermal disturbance annuli of CIP pile foundations increased the freezeback time. With increasing overlap, the freezeback time increases. Compared to warm permafrost regions, pile foundations in low-temperature permafrost regions experience a larger thermal disturbance range, and the resultant thermal disturbance annuli are more likely to overlap, which can increase the freezing time. Large-diameter pile foundations in warm permafrost regions exhibit a larger thermal disturbance range because more hydration heat is generated, and the thermal disturbance annuli more likely overlap. The freezeback time notably increases, while the permafrost around the pile foundation has not fully recovered after ten years.