Wang Yueyue, Mao Xuesong, Wu Qian, Cai Peichen, Ye Min, Yin Shunde
School of Highway, Chang'an University, Xi'an 710064, China.
Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Materials (Basel). 2024 Sep 4;17(17):4375. doi: 10.3390/ma17174375.
The hydration heat generated during the concreting of cast-in-place piles causes thermal disturbance to the surrounding permafrost, leading to its thawing. This further affects the stability of the pile foundation and degrades the construction progress. To explore the influence mechanisms of the concrete hydration heat on the permafrost temperature field around the pile, as well as that of different construction seasons on the pile-side boundary conditions and permafrost temperature field, monitoring results of on-site tests and numerical simulation were used to analyze the distribution law of the pile soil temperature field in space and time, and the pile-side boundary conditions and permafrost temperature field during construction seasons. The results show that the temperature trend of the pile foundation can be divided into three stages: a rapid rise phase (0∼2 d), a rapid decline phase (2∼10 d), and a slow decline and stabilization phase (10∼90 d). As the radial distance from the pile center decreases, there occur a corresponding acceleration in temperature increase and an elevated maximum temperature rise (MTR). The influence range of the molding temperature and the hydration heat is about 1∼2 times the pile diameter and less than 1.5 m in the depth direction. Compared to the atmospheric temperature, there is a lag in the change in the permafrost temperature caused by accumulation of ground temperature, and the significant difference between the two leads to an increased rate of heat exchange at the boundary condition. Conducting drilling operation and cast-in-place pile construction in the cold seasons is conducive to reducing the thermal disturbance to the permafrost around the pile in permafrost areas.
灌注桩浇筑过程中产生的水化热会对周围多年冻土造成热扰动，导致其融化。这进一步影响了桩基的稳定性，降低了施工进度。为了探究混凝土水化热对桩周多年冻土温度场的影响机制，以及不同施工季节对桩侧边界条件和多年冻土温度场的影响，利用现场测试和数值模拟的监测结果，分析了桩土温度场在空间和时间上的分布规律，以及施工季节中的桩侧边界条件和多年冻土温度场。结果表明，桩基的温度变化趋势可分为三个阶段：快速上升阶段（0∼2天）、快速下降阶段（2∼10天）和缓慢下降并稳定阶段（10∼90天）。随着距桩中心径向距离的减小，温度升高相应加快，最大温升（MTR）升高。成型温度和水化热的影响范围在桩径的1∼2倍左右，深度方向小于1.5m。与大气温度相比，地温积累引起的多年冻土温度变化存在滞后，两者的显著差异导致边界条件下的热交换速率增加。在寒冷季节进行钻孔作业和灌注桩施工有利于减少多年冻土地区桩周多年冻土的热扰动。
