高温隧道隔热层厚度优化及衬砌热力耦合响应分析

Optimization of Insulation Layer Thickness and Analysis of Lining Response under Thermal-mechanical Coupling in High Temperature Tunnels

  • 摘要: 衬砌作为隧道的主要承载结构,其热力耦合响应规律在高温隧道隔热衬砌研究中至关重要。以高温隧道为背景,基于现场温度监测与材料热物理参数测试数据,围绕着隔热衬砌特点与通风降温要求建立ANSYS热力耦合分析模型,揭示高温隧道施工通风调热特征,优化聚氨酯隔热层喷涂厚度,探讨二次衬砌结构的热力耦合响应规律。研究表明:隔热衬砌各层导热介质的热物理力学参数具有显著的温度效应,发泡聚氨酯的导热系数随温度的升高呈非线性增大趋势,而灰岩与混凝土的导热系数变化趋势则与之相反;三者的单轴抗压强度、变形模量均受高温影响而减小,峰值应变则随温度的升高而增大。施工通风环境中,隧道围岩温度及调热圈半径均随时间的累计而降低并逐渐趋于稳定。热力耦合作用下,二次衬砌结构主应力极值的敏感温度、主应力极值位置偏移临界温度均与二次衬砌结构温度的安全阀值(50 ℃)一致。

     

    Abstract: As the main bearing structure, the thermal-mechanical coupling response law of tunnel lining is very im? portant in the study of thermal insulation lining of high temperature tunnels. Focused on the high temperature tunnel and based on the field temperature monitoring and material thermal parameter test data, the ANSYS thermalmechanical coupling analysis model is established around the characteristics of high temperature tunnel thermal insulation lining and the requirements of ventilation and cooling. The characteristics of ventilation and heat transfer in high temperature tunnel construction are revealed, the spray thickness of polyurethane insulation layer is optimized,and the thermal-mechanical coupling response law of secondary lining structure is discussed. It is concluded that the mechanical and thermophysical parameters of thermal conductive media in each layer of thermal insulation lining structure have significant temperature effect. The thermal conductivity of foamed polyurethane material increases nonlinearly with the increase of temperature, while the temperature effect of thermal conductivity of limestone and concrete is opposite. The uniaxial compressive strength and deformation modulus of the three media decreased with the increase of temperature, while the peak strain increased with the increase of temperature. The temperature effect of thermal conductivity, strain hardening characteristics and post-peak load retention of foamed polyurethane were related to the porous structure. In the construction ventilation environment, the temperature of tunnel surrounding rock and the radius of heat regulating ring decrease with time and gradually become stable. Under the action of thermal-mechanical coupling, the sensitive temperature point of the principal stress extreme value of the secondary lining structure and the critical temperature of the deviation of the principal stress extreme position are consistent with the safety threshold (50°C) of the secondary lining structure temperature.

     

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