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为研究高纬度低海拔岛状多年冻土地区桥梁钻孔灌注桩施工后桩基温度的变化规律及回冻时间,利用智能温度监测系统采集了2根15 m长试验桩回冻前后的温度数据,实时监测了桩基的回冻进程,总结出了桩基温度随时间的变化规律并根据有限元分析结果建立了桩基回冻时间的计算方程。监测及分析表明:在冻土地温作用下桩基首先由桩底向上进行单向冻结,当大气温度降到0℃以下时桩基在上下两个方向同时冻结;回冻后桩身内部温度与桩侧土体温度基本保持一致,相同深度处温差均小于0.1℃;在入模温度相近时,1.2 m桩径试验桩的回冻时间是1.0 m桩径试验桩的1.14倍。
In order to study the variation law of the pile foundation temperature and the freezing time after the construction of the bridge bored pile in the high altitude and low altitude island permafrost region, the temperature data of two 15 m long test piles before and after freezing were collected by the intelligent temperature monitoring system , The freezing process of pile foundation was monitored in real time, the temperature variation of pile foundation with time was summarized, and the calculation equation of pile foundation freezing time was established based on the finite element analysis results. Monitoring and analysis show that the pile foundation firstly froze upward from the pile bottom under the action of frozen soil ground temperature, and the pile foundation froze at the same time in both upper and lower directions when the atmospheric temperature dropped below 0 ℃. The soil temperature in the side of pile is basically the same, and the temperature difference in the same depth is less than 0.1 ℃. When the mold temperature is similar, the thawing time of 1.2 m diameter pile is 1.14 times of the 1.0 m diameter pile.