Research On Adaptability And Durability Of Asphalt Pavement Structure In Permafrost Areas

With the development of highway construction in permafrost areas, the asphalt pavement has been widely used as its good capacity and performance. However, it increased permafrost thawing and made non-uniform melt settlement deformation of subgrade that the large heat-absorbing capacity of asphalt pavement and the special weather conditions in Tibetan Plateau permafrost areas such as intense solar radiation, long sunshine time, large temperature difference and strong wind. It also significantly affected the pavement structure and material. The service level and service life of highway is critical affected by the pavement disease caused by the above. The home and abroad scholars carried out widely study for the adaptability and durability of asphalt pavement structure in permafrost area which is always a problem puzzled them. But there is still no systematic and comprehensive evaluation method.According to the problem of the adaptability of asphalt pavement structure in permafrost area, this article analyzed the adaptability of subgrade's non-uniform melt settlement deformation of five types of asphalt pavement structures based on the preliminary study on additional stress. It also analyzed the adaptability of subgrade top temperature field of asphalt pavement structures which is evaluation of the subgrade top temperature change. The adaptability study shows that reduced the temperature at subgrade top by increasing the thickness of the structure set the layer of graded crushed stone or asphalt macadam is benefit to protect the permafrost. According to the problem of the durability of asphalt pavement structure in permafrost area, this article analyzed the durability of temperature stress of five types of asphalt pavement structures by the pavement crack possibly caused by the temperature stress. The model of comprehensive action of the subgrade's non-uniform melt settlement deformation and vehicle load is established to analyze the durability of asphalt pavement structures with the varying thawing settlement radius, thawing settlement depth and modulus. The durability study shows that the temperature stress of asphalt surface is reduce with the increasing thickness of the layer of graded crushed stone, while the temperature stress of asphalt surface is increased with the increasing thickness of the other layer. It can effectively reduce the temperature stress of asphalt surface that set the transition layer of graded crushed stone. To the same asphalt pavement structures, the comprehensive stress of structure layers is reduced with increasing thawing settlement radius when the thawing settlement depth is fixed. It is increased with increasing thawing settlement depth when the thawing settlement radius is fixed. It can effectively reduce the comprehensive stress that set the layer of graded crushed stone or asphalt macadam. Finally, the adaptability and durability of five types of asphalt pavement structure is evaluated though the four above indexes by the "barrel principle". It provided a guidance and basis to reasonable select the pavement structure in permafrost areas.