考虑通风与围岩条件的寒区隧道温度场模型及作用规律研究

为了解决寒区隧道温度场的预测问题,为寒区隧道抗冻设防提供指导,结合传热学、流体力学的基本方法,根据能量守恒原理,推导寒区隧道风流温度场的传热模型,并在此基础上,借助有限差分方法,探讨通风和围岩条件对寒区隧道温度场分布的作用规律。研究结果表明: 1)入口风温越低,风流速度越大以及断面越大,相同位置处洞内温度越低,这是由于进入洞内的冷空气更多,入口风温每降低5 ℃,同位置洞内风流温度平均降低3. 8 ℃; 2)风流温度决定了离壁面一定范围的围岩温度大小,风流温度越低,冻结深度与受到影响的围岩范围更大; 3)初始岩温越大,围岩温度分布曲线越陡峭,围岩导热系数则相反,且初始岩温每增加 5 ℃,冻结深度减少0. 24 m,受影响的围岩径向深度减少0. 32 m。

Model and Action Law of Temperature Field of Tunnel in Cold Region Considering Ventilation and Surrounding Rock Condition

The prediction of tunnel temperature field in cold region is of great significance to the freeze-proofing of tunnel. As a result, the heat transfer model of the cold and wind tunnel temperature field is deduced based on the basic methods of heat transfer and fluid mechanics and principle of conservation of energy. And then the influence of ventilation and surrounding rock conditions on the temperature field distribution of tunnel in cold region is analyzed by finite difference method. The research results show that: (1) The lower the inlet wind temperature and the larger the wind velocity and cross-section, the lower the overall temperature inside the tunnel, which due to more cold wind; for every 5 ℃ decrease of inlet wind temperature, the average temperature of air flow inside the tunnel at the same position decreases by 3. 8 ℃. (2) The wind temperature determines the surrounding rock temperature in a certain range from the wall surface; the lower the air temperature, the greater the freezing depth and the affected surrounding rock range. (3) The initial temperature and thermal conductivity of surrounding rock determine the radial temperature distribution curve of surrounding rock; the larger the thermal conductivity of surrounding rock is, the flatter the temperature distribution curve is. Moreover, when the initial rock temperature increases by every 5 ℃, the freezing depth will decrease by 0. 24 m, and the radial depth of affected surrounding rock will decrease by 0. 32 m.