| According to the Plan of the Civil Aviation Administration,China will carry out large-scale airport construction in the northeastern high-latitude zone.The difficulty in constructing runway in permafrost regions is that permafrost is extremely unstable and susceptible to temperature.At present,scholars at home and abroad have conducted in-depth research on the construction and maintenance of highways and railways in permafrost regions,and have accumulated fruitful research results.However,research on airport runway temperature control technology is still blank.With the help of finite element software,this paper studies the long-term variation of natural soil-based temperature field and temperature field of only running track soil under the condition of global warming.The influence of main physical parameters of gravel pack on the cooling effect of gravel layer is discussed.And the cooling effect of the combined measures and single measures,as well as the optimal cooling rate of the gravel layer at different annual temperatures are analyzed.The main work and achievements are as follows:1.Using a cryogenic laboratory containing a refrigeration system to conduct indoor cooling experiments on the gravel and monitor changes in the soil temperature field.Meanwhile,a full-scale finite element model was established to compare the experimental temperature field results with the finite element simulation temperature field results and analyze the error causes to verify the correctness of the finite element modeling method.2.According to the climate monitoring data and engineering construction experience in Northeast China,the finite element model is established.The finite element model runway structure and the thickness of the pavement are all set according to the specifications.The long-term variation of the temperature field of the natural soil foundation and the temperature field of the runway without temperature control is studied when the annual average temperature is between 1 °C and-6 °C.The results show that the laying of the runway causes severe degradation of the permafrost.Thus temperature control measures must be taken to protect the runway soil foundation in order to maintain the normal operation of the runway.3.A finite element model with gravel-filled layer was established to study the cooling effect of the particle size of the crushed stone and the laying position of the gravel-filled layer at an annual average temperature of 1~-6 °C.By analyzing the single measure of gravel-filled layer and combination of the layer of gravel and he cooling effect of the EPS insulation board measures shows that when the annual average temperature is the same,the particle size of the crushed stone is positively correlated with the cooling effect,the cooling effect of the 2~4cm gravel is the worst,the cooling effect of 10~15cm is the best,and the remaining particle size’s cooling effect is between the above two.The laying position of the gravel layer has a great influence on the cooling effect,and the position of the gravel filling layer is closer to the runway,the better the cooling effect is.When the annual average temperature is higher than-4 °C,the gravel layer The cooling effect of single cooling measures is better than the combination of gravel layer and EPS insulation board.4.The effect of the thickness of the gravel pack on the temperature field of the soil foundation is studied,and the absolute value of the cooling effect and the optimal cooling rate of the gravel pack are obtained.According to the simulation results,considering the difficulty of construction in cold regions,the conclusion is as follows: in the region where the annual average temperature is 1~-2°C,the suitable thickness of the gravel layer is 3m.When the annual average temperature is-3 °C and-4 In the area of °C,the thickness of the gravel layer is preferably 2~3m.In the area where the annual average temperature is-5°C and-6°C,the thickness of the gravel layer is preferably 2m.A large number of numerical simulations of the main physical parameters of the gravel pack indicate that the use of this temperature control measure in the construction of airport runway in the permafrost regions of Northeastern China is of a certain reference significance. |
