高寒高海拔隧道保温层敷设方式及设计参数优化

为了深入探究高寒隧道保温层敷设方式及其设计参数优化的问题，以高寒高海拔特长珠角拉山隧道工程为背景，通过数值模拟重点研究了保温层敷设方式、设计厚度及导热系数参数的选择，并讨论了当地气温变化与保温层设计参数的关系。研究结果表明：在寒区隧道保温层设防区段，贴壁式敷设方式最佳；随着保温层厚度的增加，洞内冷空气影响范围逐渐减小，调热圈径深随保温层厚度变化的趋势用公式表达为f（x_h）=3.039e^{-0.280 9x_h}+13.8e^{-0.009 322x_h}；基于调热圈径深随保温层厚度增加的变化速率曲线及隧道结构安全，建议保温层厚度设计为5~10 cm；随着保温材料导热系数的增大，洞内冷空气影响范围逐渐增大，调热圈径深与导热系数关系趋势用公式表达为f（x_λ）=15.47e^{0.287 4x_λ}-3.829e^-39.05x_λ；基于调热圈径深随导热系数变化速率曲线及隧道结构安全，建议保温材料导热系数取0.020~0.035 W·（m·K）^-1；在假定保温层厚度为5 cm，导热系数为0.022 2 W·（m·K）^-1，通风时间4个月的情况下，只有当洞内气温大于-15℃时才能保证支护结构和围岩不受冻害影响。研究成果可为川藏铁路建设提供指导作用。

Laying Method and Design Parameter Optimization of the Thermal Insulation Layer in Alpine and Altitude Tunnels

To study the laying method and design parameters of the thermal insulation layer in alpine tunnels, the laying method, design thickness, and thermal conductivity of thermal insulation layers were thoroughly studied through numerical simulation, and the relationship between local temperature change and the design parameters of the thermal insulation layer were discussed. The results show that the wall-mounted laying method is the best in the insulation layer fortified section of the tunnel in cold regions. With increased insulation layer thickness, the influence range of cold air in the tunnel decreases. The trend of the diameter depth of the heat regulating ring changing with the insulation layer thickness is expressed as follows:f(x_h)=3.039e^{-0.280 9x_h}+13.8e^{-0.009 322x_h}. Based on the change rate curve of the diameter depth of the heat regulating ring with an increased insulation layer thickness and tunnel structure safety, it is suggested that the insulation layer thickness should be designed to be between 5 and 10 cm. With increased thermal conductivity of the insulation material, the cold air influence range in the tunnel increases. The relationship trend between the diameter depth of the heat regulating ring and the thermal conductivity is expressed as follows: f(x_λ)=15.47e^{0.287 4x_λ}-3.829e^-39.05x_λ. Based on the rate curve of the diameter change and heat regulating ring depth with thermal conductivity and tunnel structure safety, it is suggested that the thermal conductivity of thermal insulation materials should be between 0.020 and 0.035 W·(m·K)^-1. Under an assumed thickness of a 5 cm thermal insulation layer, a thermal conductivity of 0.022 2 W·(m·K)^-1, and a ventilation time of 4 months, only when the tunnel temperature is higher than -15℃, can the supporting structure and surrounding rock be protected from freezing damage. The research results can provide safety guidance for the Sichuan-Tibet Railway.