多年冻土区桩基温度场研究

为了解决多年冻土区桥梁桩基浇筑混凝土对冻土层地温的影响，把握后续工程施工，需要对多年冻土区桩基温度场进行认真分析与研究。结合冻土桩的特点，根据冻融循环条件下土体热量迁移的基本规律，基于多孔介质和热力学理论，建立了多年冻土区桩基温度场控制方程。该控制方程不仅包括了热传导和相变潜热对温度分布的影响，而且考虑了混凝土水化热的释放规律，并将研究成果与的西藏某大直径灌注桩温度场现场试验结果进行对比分析。结果表明：所建立的冻土区桩基温度场控制方程计算结果与实测结果吻合较好。在此基础上，应用该模型作数值分析，着重分析了不同深度处桩侧土层温度随时间变化规律和混凝土浇注后不同时期温度沿桩径方向的变化规律，于解决西部多年冻土地区公路运营安全和行车性能，准确掌握多年冻土地区已建桥涵和新建桥涵基础稳定性，具有非常重要的理论和实际意义。

Temperature distribution along piles in permafrost regions

In order to control the influence of pouring concrete of bridge piles on the ground temperature in permaforst regions and guide the subsequent engineering construction, it is necessary to analyze and study the temperature distribution along piles. Considering the characteristics of piles in permafrost regions and the basic rule of heat transfer in soil during freeze-thaw cycling, the control equations of temperature field in permafrost regions are established based on the theories of porous media and thermodynamics. The effects of heat conduction and latent heat on the temperature distribution are considered, and the release rule of concrete hydration heat is studied by control equations. The research results are compared with the in-situ monitored temperature field of a bored pile with large diameter in Tibet. It is concluded that the calculated results are in good agreement with the in-situ monitoring data. Based on this, emphasis is laid on analyzing the changes of soil temperature around the pile in different depths with time and temperature distribution in the radial direction of pile diameter in different phases. It is of great theoretical and practical significance to the foundation stability of bridge and culvert as well as the traffic operation safety of highways and railways in permafrost regions