Analysis On Cooling Roadbed’s Parameter Optimization And Cooling Effect In Cold Region

As a special type soil, permafrost is sensitive to climate changes and human engineering activities. With global warming aggregates and increasingly frequent human engineering activities on permafrost, its original thermal equilibrium has suffered from destruction which results in project plant disease in permafrost regions. Roadbed projects in Tibetan Plateau which is an area with widespread permafrost is faced with various difficulties. Since the roadbed is paved on permafrost, differential settlement beneath of roadbed may occur because of the decline of permafrost table caused by thermal equilibrium imbalance, which is the major cause of roadbed destruction in permafrost region. As a result, how to reduce the impact of roadbed construction on permafrost has been a research subject.For this purpose, scholars have come up with new cooling roadbed structure which uses the water stored in water tanks buried beneath the roadbed for heat exchange to achieve thermal balance between permafrost and the roadbed so as to protect permafrost. But they haven’t provided reference values for relevant parameters. To address this problem, ANSYS is applied to optimize related parameters. To begin with, the impact of water layer thickness and burying location of water tanks at a certain temperature on cooling effect is analyzed as well as compared with ordinary roadbed, based on which further analysis on the relationship among different temperature, water layer thickness, and burying location. And the main conclusions are given as follows:①Compared to ordinary roadbed, the roadbed with water layer is able to protect permafrost beneath it remarkably in the long-term use process.②For any combination of water layer thickness and burying location,permafrost table will always decline gradually in the long-term use process. However, permafrost table declines slowly compared to ordinary roadbed, indicating that such roadbed structure plays a positive role in permafrost protection.③Both water layer thickness and its burying location in the roadbed have direct impact on cooling effect. And the thicker the water layer is and the shallower burying location can be, the more remarkable the cooling effect will be. However, these two parameters have differential impact on cooling effect. The impact of water layer thickness on cooling effect is higher than that of burying location.④Having obtained the relation curve of water layer thickness, burying location, and temperature, it can be seen from curve analysis that; in order to obtain good cooling effect, the horizontal thickness of water layer thickness in the same burying location deepens with the increase of annual average temperature; when temperature rises, the increment of water layer thickness has some certain relationship with its burying location, and the shallower of burying location is, the smaller of increment of thickness will be; in the context of global warming, the longer it is used, the thicker the water layer will be; when the average temperature remains the same, water layer thickness deepens with the depth of burying location in order to obtain good cooling effect, and the increment of thickness declines gradually with the burying location deepens.