Study On Cooling Technology For Control Of Runway Base Temperature Field In Permafrost Region

According to the Civil Aviation Administration's development plan for the future civil aviation industry,large-scale airport construction will be carried out in permafrost regions in China.However,the construction of airport runways in permafrost regions will face the difficulty of frozen soils.Due to the unstable nature of frozen soils and their susceptibility to temperature influences,the construction of runways on frozen soils will also affect the temperature field of frozen soils.This in turn affects the bearing capacity of the frozen soil,which may eventually threaten the normal operation of the airport runway.However,there are few researches on the cooling technology for the temperature field control of the runway foundation of airport runways in permafrost regions.In this regard,with the help of finite element numerical software,this paper proposes to use the active cooling technology of the ventilation duct to control the temperature field of the runway foundation.The main work and results are as follows:1.Based on the analysis of the characteristics of permafrost in Northeast China and the summary of the problems faced by the construction of the runway in permafrost area,combined with the research on the principles of various cooling technologies in permafrost area,the main cooling measures,which are composed of three cooling technologies,i.e.ventilation pipe,gravel layer and thermal insulation layer,are put forward.In consideration of the improvement of cooling efficiency,a new cooling measure is proposed—— Runway foundation of rectangular through wall vent pipe.2.Combined with the natural conditions of soil and climate in Northeast China,the finite element calculation model of the runway foundation of the rectangular through wall ventilation pipe is established,and the cooling mechanism of the rectangular through wall ventilation pipe foundation is analyzed.The finite element model of the runway foundation of the rectangular through wall ventilation pipe under the two ventilation modes of mechanical ventilation and natural ventilation is obtained.3.The parameters of the rectangular ventilation pipe,including section form,section size and opening rate of the pipe wall,are calculated and analyzed to determine the parameters of the ventilation pipe with the highest cooling effect and energy saving.The coreparameters of the cooling work of the rectangular ventilation pipe under the two ventilation modes,including the ventilation wind speed,ventilation time and pipe spacing,are analyzed and calculated by the finite element method,and the core parameters with the best cooling effect under the two modes are determined.4.This paper analyzes the cooling effect of the runway foundation of the rectangular through wall ventilation pipe under the two ventilation modes.By comparing the short-term use effect in one year with the long-term use effect in 30 years,it is found that the rectangular through wall ventilation pipe foundation under the natural ventilation mode also has a good cooling effect.Considering the factors of high efficiency and energy saving,it is finally determined that the rectangular through wall ventilation pipe foundation under the natural ventilation mode is preferred.5.The reliability of the finite element model method and the correctness of the calculation results are verified by the laboratory test of frozen soil and the comparison with the finite element calculation of the established finite element model.