寒区路基遮阳的热流平衡模型及其应用

Thermal balance of shading boards over cold-region roadbed: Modeling and application

在路肩上铺设遮阳板是冷却多年冻土路基的一种重要工程措施,遮阳板上下表面及路肩的热流量控制其降温效果,但现有的研究大多分析实地遮阳板的降温效果以及遮阳板的设计参数。基于能量平衡原理,构建遮阳板与路肩的热流平衡理论模型并利用实测数据验证模型的准确性。经过对模型参数敏感性分析发现:减小遮阳板下表面热辐射系数可以有效地降低遮阳板到路肩表面的长波辐射量,从而降低路面温度。而增大遮阳板下表面的风速对减少路肩热吸收量的贡献很小。因此,减小板下表面的热辐射系数同时将遮阳板尽可能安设在接近路基表面的位置,此举既可以有效冷却路基又可以尽量避免遮阳板遭受风力破坏,有利于一步推广遮阳板的使用。

One of cold-region roadbed cooling techniques is to install shading boards on the shoulder of the embankment over permafrost stratum. Most researches currently focus mainly on the temperature evolution of the roadbed under the board and on the optimal design of the board. The cooling mechanism of the board, however, is not available. The heat flux balance between the board and the shoulder is simulated, and the model is validated using the measured data from an in-situ shading board. The results show that the cooling effects of the board can be greatly promoted by decreasing the thermal emissivity of the lower surface of the board, and/ or can be possibly enhanced by increasing the albedo of the upper surface of the board. Increasing the wind under the board, however, may contribute negligibly to the cooling effects. This means that installing the board as closely as to the shoulder surface and decreasing the thermal emissivity of the lower surface of the board can both promote the cooling effects and prevent the board from wind damage simultaneously.