Research On Thermal Stress Of Asphalt Pavement In Permafrost Areas

The special temperature conditions in permafrost region, such as continuous low temperature, cooling suddenly, large temperature differences and strong wind are common, and the effect to the pavement structure and material is obvious. At present, the design of pavement structure in permafrost regions didn't consider the influence and related research were correspondingly less. It may have great difference in designing pavement structure according the standard method to the general area, and the service life can not reach the design life.This study starts from the climate characteristics in Qinghai-Tibet Plateau and the effect to the pavement structure, takes Qinghai-Tibet Highway as an example, based on the study of thermal regime, the thermal stress and the effect factor on asphalt pavement, cracks estimates and fatigue life in asphalt surface course, pavement structure adaptation on temperature in permafrost region, many research were studied. Aiming at selcecting the pavement structure more reasonable, prociding direction and guidance to prefect the asphalt pavement design method. Research shows that, the layer thickness of pavement structure had less effect on thermal stress in asphalt pavement. To increase the thickness of asphalt surface course, cement stabilized gravel, or asphalt treated stone, the thermal stress of asphalt surface course increased. But it deincreased to increase the thickness of graded crushed rock. The pavement structure combination had certain effect on thermal stress in asphalt pavement. In a word, to set a graded crushed rock layer can effectively reduce the thermal stress of asphalt surface course. Stiffness modulus and the index of temperature shrinkage of asphalt mixture had great influence on the thermal stress in asphalt surface course, the less of the stiffness modulus and the index of temperature shrinkage of asphalt mixture, the less of the thermal stress in asphalt surface course. Comprehensively analyzed the result of asphalt surface course thermal stress, thermal stress level, and the fatiguelife, to set a graded crushed rock layer was advantageous in the temperature adaptability of the asphalt pavement structure. The temperature adaptability of flexible pavement structure was well than semi-rigid asphalt pavement structure while the number of layers and the total chickness of pavement structer were the same.