正盘台隧道洞内空气和围岩温度场分析

Analysis of Temperature Field of Air and Surrounding Rock in Zhengpantai Tunnel

基于京张高铁第一长隧道正盘台隧道为研究对象,根据现场实测温度数据,应用ANSYS有限元软件求解计算模型温度场。以热传导方程为理论基础,分析影响隧道温度场的因素,并通过控制变量法计算得出不同工况下正盘台隧道内部温度场的变化规律,为研究隧道内部温度场问题及运营之后的防寒保养工作提供了一定的理论和数据基础。分析结果表明:通过计算值与实测数值的对比可发现,在当地最冷月,隧道内温度呈现"两头低、中间高"的趋势;隧道内围岩的初始温度是影响隧道整体温度场的主要因素,初始温度越高的工况,隧道整体温度越高,冻融圈深度和冻结里程越小,温度每升高5℃,冻结里程减小160 m;环境风速对于隧道进出口1000 m左右的区间段影响较大,此区域应作为防寒抗冻的重点;冻结时长是影响冻融圈深度的关键因素,冻结时间一个月、两个月、三个月的冻融圈深度为2.1、3、3.6 m。

To study the temperature field of the Zhengpantai Tunnel in Hebei Province, a calculation model was established using the ANSYS finite element software based on the measured temperature data. According to the theory of heat conduction equation, many factors affecting the temperature field of the tunnel were analyzed, the variation of the internal temperature field was calculated in the control variable method, and the temperature field problem in the tunnel was solved, which provided basis for the follow-up cold protection designs. The results show that the temperature is low at two terminals and high in the middle sector in the winter, for which the initial temperature of the surrounding rock in the tunnel is the main factor on the overall temperature field of the tunnel. The higher the initial temperature, the higher the overall temperature of the tunnel, the smaller the freezing and thawing circle depth and the frozen distance. Every 5 ℃ increase can reduce the frozen distance by 160 m. The ambient wind speed can affect about 1 000 m from the two ends of the tunnel, thus the wind-affected segment shall be paid with a good attention for cold and frost protection. In addition, the freezing time is the key factor affecting the depth of the freeze-thaw cycle, and the depth of freeze-thaw circle. The freeze-thaw cycle depth of one month, two months, and three months is 2.1, 3, and 3.6 m respectively.