寒区公路隧道温度场及保温层的研究

Research on the Temperature Fields and Insulating Layers of Highway Tunnels in a Cold Region

随着寒区公路隧道的不断增多,寒区隧道的保温问题也受到广泛重视。为了分析计算此类隧道施工过程中的温度场,验证寒区隧道保温设计的必要性,确定保温设计的经济性和有效性,文章以某市西山隧道为背景,结合东北冻土的热力性质特点,利用大型有限元计算程序Ansys,对寒区隧道进行了模拟分析,并且将计算的理论数据与实际测定的数据进行对比,分析隧道开挖后围岩温度场的分布、初期支护以及二次衬砌的温度变化过程,对隧道保温效果进行评定。数据对比表明,将保温层设置在二次衬砌外侧是比较合理的,但在东北寒区,对于断面半径达7m的大断面隧道,仅使用40 mm厚的PU硬质聚氨酯泡沫板作为保温材料是不合理的。为使设计经济合理,保温材料在径向上可以采用不同的厚度。

More and more highway tunnels have been built in cold regions,and this paper addresses this topic.In order to analyze and calculate the temperature field,validate the necessity of the design of an insulating layer and confirm the economical efficiency and effectiveness of highway tunnels in cold regions,FEM Ansys was used to simulate and analyze these kinds of tunnels using the Xishan Tunnel as an example and taking into account the thermodynamic characteristics of permafrost in Northeast China.The calculated results of numerical simulation and measured data are compared to study 1） the temperature distribution of the surrounding rock after tunnel excavation and 2） the temperature variation process of the primary and secondary lining.The effect of heat insulation in the tunnel was also evaluated.Results showed that it is reasonable to put the insulating layer at the outside of the secondary lining,and it is not reasonable to use 40mm thick PU rigid polyurethane foam board as the heat insulating material for a large tunnel with a radius of 7m in the cold region of Northeast China.In order to make the design economic and rational,the insulating material can have a different thickness in the radial direction.