Finite Element Modeling Of Asphalt Pavement Based On CT Technology And Randomness Study Of Heating Temperature Field

Highway is an important link in the rapid development of China ’s economy.With the gradual expansion of highway scale,various diseases inevitably occur in the early construction of highway pavement.In order to maintain good road performance,it is necessary to maintain highway pavement regularly.Hot in-place recycling technology has been widely used in highgrade highway maintenance in China due to its advantages of 100 % utilization of old materials and fast construction speed.In the construction process of hot in-place recycling technology,the heating effect of asphalt pavement is the key to the quality of recycling construction,and the heating temperature of asphalt pavement needs to be strictly controlled.In addition,because the asphalt pavement is composed of aggregate,asphalt mortar and voids,it will be affected by random factors during the preparation process,and different materials have different thermophysical properties.Most of the existing studies replace it with equivalent parameters.In order to establish an accurate asphalt pavement model,this thesis further improves the temperature field model of asphalt pavement from the perspective of its meso-structure,and studies the influence of random factors on temperature distribution.The main research work is as follows :1.Complete the CT image processing of asphalt concrete sample block.In order to distinguish the different components inside the asphalt concrete,the gray image of the asphalt concrete sample block is obtained by CT scanning,and the image enhancement processing such as histogram equalization,piecewise linear enhancement and sharpening is performed.Then the median filter is used to filter the highlighted noise.Finally,the multi-level threshold segmentation algorithm is used to segment the aggregate,asphalt mortar and voids to obtain the three-dimensional spatial distribution of different materials of the asphalt concrete sample block.2.The finite element analysis model of asphalt pavement temperature field is established and verified by experiments.Based on the basic theory of heat transfer,the finite element method combined with the CT image processing results of asphalt concrete sample block is used to establish the temperature field analysis model of asphalt pavement,and the precise integration method is used to solve it.Through experimental verification,the maximum error of the model is 3.4 %,and the model is used to analyze the heating uniformity of asphalt pavement.The results show that the temperature difference gradually decreases with the increase of heating time and depth.3.The prediction model of asphalt pavement temperature field is established and the randomness analysis is carried out.Considering the distribution characteristics of influencing factors of asphalt pavement temperature field,the Kriging theory is used to establish the prediction model of asphalt pavement temperature field based on the established analysis model.After prediction and comparison,the prediction error of the model is less than 5 %.The model is used to analyze the distribution characteristics of temperature at different depths of asphalt pavement,and then the sensitivity analysis of influencing factors of asphalt pavement temperature field is carried out from two aspects of single factor and multiple factors.The results show that the thermal conductivity,density,specific heat capacity of basalt material and the specific heat capacity of asphalt material have great influence on the temperature field.