Study On Temperature Stress Of Asphalt Mixture Based On Regional Cooling Characteristics

Asphalt pavement is widely used in China's high-grade roads because of its good road performance.Due to the repeated action of external temperature and traffic load for a long time,asphalt pavement will appear cracks,which has an important impact on the integrity of its structure.In this paper,according to the climate characteristics of typical regions in China,based on the measured temperature data from 2012 to 2019,the frequency of cold wave and cold air activity in each region is summarized.The finite element method is used to simulate the low-temperature constrained freeze-thaw test of asphalt mixture,and the variation law of temperature stress of asphalt mixture in each region is studied.Firstly,by collecting the meteorological data of each typical area in China,the 18 cities are divided into six typical areas according to their geographical location.According to the definition of cold wave,the cold wave distribution and cooling range of each city from 2012 to 2019 are determined.Secondly,the viscoelastic mechanical parameters and cohesive element parameters of asphalt mixture are determined by comparing the simulation analysis with the measured data.The feasibility of the finite element method to study the temperature stress is verified by ABAQUS finite element software simulation of low temperature freeze-fracture test.Finally,according to the changes of temperature and road surface temperature when cold wave occurs in each typical area,the variation law of temperature stress of asphalt mixture in different regions is analyzed,and the temperature fatigue life of asphalt mixture under the action of the temperature amplitude of the strongest cold wave in each typical area is predicted.The following conclusions are obtained through this study:(1)The distribution of cold wave in each typical area shows a decreasing trend from north to south,mainly in November,December and January in winter,October alternating with autumn and winter and February alternating with winter and spring.The distribution of cold wave is the most in Northeast China,followed by North China,and the lowest in other regions.(2)Under the same initial temperature,the temperature stress of asphalt mixture increases with the increase of cooling rate at the same temperature level,and the lower the cooling rate,the lower the temperature when the temperature stress reaches the ultimate tensile stress;under the same cooling rate,the temperature stress of asphalt mixture increases with the increase of initial temperature at the same temperature level,and the higher the initial temperature is When the temperature stress reaches the limit tensile stress,the higher the temperature.(3)Most of the maximum temperature stress appears in December in winter,and the time is from 2:00 am.to 8:00 am.under the strongest cold wave,the temperature fatigue life of asphalt mixture in North China and Northeast China is the shortest,and that in East China is the longest.