Research On Temperature Field Characteristics Of Airfield Runway Subgrade In Permafrost

According to airport construction planning,China will continue to carry out the airport construction in Permafrost Regions.Permafrost is a kind of special soil which is sensitive to temperature and has obvious rheological property.The small change of frozen soil temperature will directly lead to the great change of frozen soil strength.Therefore,it is the foundation of the airport construction to master the regularities of distribution of the ground temperature field of permafrost.The airport construction in permafrost region of China has just started,and there is no systematic report about this respect.Due to the wide characteristics of the airfield runway and the special requirements cannot above ground level,the existing research results on roads and railways are not fully applicable to airports.Thus,the characteristics of airfield runway ground temperature field in permafrost regions are an urgent problem.The author uses ABAQUS finite element software,combined with the characteristics of the airfield runway,simulation analysis of the permafrost area of different pavement width,different pavement types,climate warming factors and the change regulation of the temperature field of runway foundation.The main research contents and results are as follows:(1)Based on the finite element method,the temperature field calculation model of airfield runway foundation and highway subgrade in permafrost regions is established,through the comparative analysis,it is found that there is a big difference in the temperature distribution between the two foundations.Compared with the highway subgrade,the foundation of airfield runway has deeper melting,greater disturbance to the frozen soil.It shows that existing research results on roads and railways are not fully applicable to airports.Furthermore,the validity of the finite element model is verified by the field test of road temperature field.(2)Study on the change regulation of ground temperature field of airfield runway in permafrost regions with different pavement width,the result indicated that,with the increase of the pavement width,the higher the soil temperature,the larger the area of the soil and the deeper the melting depth.The annual changes rule of the temperature field and the influence range of the airfield runway on the ground temperature field are obtained.Finally,thequantitative relationship between the melting depth and pavement width and service life is established.(3)Comparative analysis of temperature field of asphalt concrete pavement and cement concrete pavement,the results show that the melting depth of ground temperature field of cement concrete pavement is smaller,and the melting time is shorter than that of the asphalt pavement,and the thermal stability is better.At the same time,the correlation between the width of different concrete pavement and the depth of foundation settlement is given.(4)Based on the analysis of temperature field of runway foundation under different climate warming.The results show that climate warming has a significant effect on the runway foundation melting depth in Permafrost Regions.Furthermore,the relationship between the melting depth and the rate of climate warming is given.(5)Based on the numerical analysis of the temperature field of the airfield runway foundation,it can be concluded that the thermal baffle can greatly reduce the thaw depth of the foundation,this is particularly obvious for narrow pavement protection.And,thickness of thermal baffle is thicker,the depth of embedment is shallower,then the protection of permafrost is better.