Analysis Of Temperature Field And Temperature Fatigue Life Of Asphalt Pavement In Gobi Desert Area Of Gansu Province

The temperature field and temperature stress of asphalt pavement are the key factors causing ruts,cracks and hugging of asphalt pavement in the Gobi Desert area of Gansu province.The periodic changes of temperature field and temperature stress seriously affect the service life of asphalt pavement.Therefore,based on the study of temperature field and temperature stress of asphalt pavement,the analysis of temperature fatigue life of asphalt pavement has great theoretical and practical significance,and provides a reference for the structural design of asphalt pavement in the Gobi Desert area of Gansu province.In this paper,based on the literature review and field investigation of the climate characteristics,asphalt pavement structure and diseases in the Gobi Desert area of Gansu province,two asphalt surface layers(the first type,Ⅰ type asphalt surface structure,15 cm AC-16 type asphalt mixture)in different periods(high temperature period,low temperature period and normal temperature period)in the representative area of the Gobi Desert in Gansu Province were measured by experiments.The second type,Class Ⅱ asphalt surface structure,4cm AC-16 asphalt mixture +5cm AC-20 asphalt mixture +6cm AC-25 asphalt mixture)temperature data and comparative analysis.According to the measured temperature data and the collected meteorological data at the measured site,the prediction models of the road surface and the internal temperature field of the two asphalt surface layers in different periods were established by using regression analysis method.Based on the basic principle of heat transfer and on the premise of determining the thermal property parameters of asphalt pavement material,the temperature field prediction model of asphalt pavement was constructed by using the finite element software ABAQUS and compared with the measured data to verify the reliability of the model.The asphalt pavement constructed by finite element software(4cm AC-16 asphalt mixture +5cm AC-20 asphalt mixture +6cm AC-25 asphalt mixture)with 50 cm cement stabilized sand gravel base was constructed by inputing meteorological data of the representative areas of Gansu Gobi Desert(Wuwei,Jinchang,Zhangye,Jiuquan and Lanzhou New District).In the following is the temperature field model of soil foundation),temperature data are extracted,and the temperature stress and temperature fatigue life of asphalt pavement are calculated and analyzed according to the existing formula.The main conclusions are as follows:(1)The average annual maximum temperature is 32～37℃,the average annual minimum temperature is-30～-20 ℃,the average annual maximum temperature difference is 50～65℃,the average annual precipitation is 60～180mm,and the average annual wind speed is 3.0～4.2m/s in the Gobi Desert.Due to the climatic characteristics and the structure combination form of asphalt pavement in the Gobi Desert area of Gansu province,the most common diseases of asphalt pavement in this area are ruts and cracks,among which the ruts are mainly unstable ruts,and the cracks are mainly temperature shrinkage cracks and temperature fatigue cracks.(2)The measured temperature data at different depths of the two asphalt surface layers are relatively close,which indicates that many scholars regard the asphalt surface structure as layer 1 when using finite element software to simulate the temperature field of asphalt pavement,and the method of analyzing the temperature field of asphalt pavement is feasible.(3)Compared and analyzed the predicted values and measured values of the temperature field prediction models established in this paper for the road surface and the internal temperature field of the two asphalt surfaces in different periods,the predicted results are good.Compared with the prediction model of asphalt pavement temperature field established by other scholars,the model established in this paper is more suitable for the Gobi Desert area in Gansu Province.(4)The temperature data of asphalt pavement calculated by ABAQUS finite element software is compared with the measured temperature data.The comparison results show that the temperature field simulation of asphalt pavement by ABAQUS finite element software has high reliability.(5)The calculated temperature stress at the asphalt surface in Gansu Gobi Desert area is the largest,and the temperature stress decreases gradually with the increase of the depth from the road surface,and the temperature stress or temperature fatigue failure is most likely to occur at the road surface.(6)Among the five representative regions of the Gobi Desert in Gansu,the daily temperature difference of Lanzhou New Area is smaller than that of the other four regions,and the temperature fatigue is relatively less obvious.The temperature fatigue life of the asphalt pavement in this area is 10.6 years,which is much higher than that of the other four regions.