玉希莫勒盖隧道温度场及保温层厚度的研究

Study on the Temperature Field and Insulation Layer Thickness of the Yuximolegai Tunnel

新疆G217国道玉希莫勒盖隧道位于高海拔季节性冻土地区,为确保隧道运营的安全性,需对其温度场及保温层厚度进行研究。针对这一问题,文章首先采用自动温度监测仪对该隧道进行现场观测,得到隧道不同径向深度处的温度变化规律;通过室内试验测定相关计算参数,并根据现场温度监测的拟合分析结果确定模型边界条件,将该隧道未铺设保温层时的温度场计算结果与现场温度监测结果进行对比,可以看出两者变化趋势基本吻合;然后进一步分析现场采用5 cm保温层的可靠性,计算结果表明,在衬砌壁后仍存在0.4m的冻结范围;同时分析了冻结锋面的扩展规律,得出拱肩和底板是冻结锋面扩展速度最快、距离最远的部位,视为整个断面的危险位置;最后以拱肩和底板处衬砌外侧的温度是否为0℃作为判据计算了该隧道所需保温层厚度。文章研究成果对高山季节性寒区隧道的建设具有一定的指导意义。

The Yuximolegai tunnel on the G217 national highway in Xinjiang is located in a high-altitude seasonal frozen-ground region. In order to ensure its safe operation, it is necessary to study its temperature field and deter- mine a proper insulation layer thickness. An automatic temperature monitor was used to obtain temperature varia- tions at different radial depths of the Yuximolegai tunnel. Based on the calculating parameters determined by labora- tory tests, the model boundary conditions were determined by fitting the analytical results of field temperature moni- toring. The temperatures obtained by field monitoring were compared with those determined by the temperature field calculation without an insulating layer, and their changing tendencies are basically in agreement. Further analysis was conducted on the reliability of the 5 cm-thick insulating layer used in the field, and the calculations show that there is a freeze scope of 0.4 m behind the lining wall. The expanding law of the freezing front was analyzed and re- suits indicate that the freezing front expands fastest and for the farthest distance on the spandrel and bottom, where the most dangerous positions on the whole cross section are. Ultimately, the required thickness of the insulating lay- er was calculated according to the criteria of whether or not the temperature outside the spandrel and bottom lining layer is 0℃.