Study On Paving Uniformity Of Spiral Cloth For Wide Asphalt Mixture Pavement

The asphalt mixture paving machine is one of the important equipment for asphalt pavement.The asphalt mixture under the delivery of the spiral fabric is due to its complex force and movement.This affects the service life of the pavement.To this end,this thesis relies on the Zhengzhou Road and Bridge project of Henan,and uses the spiral fabric as the research object to establish the asphalt mixture uniformity evaluation criteria.Digital image processing technology has carried out actual measurement analysis of paving uniformity.The main research work is as follows:①The structural composition and working principle of the spiral spreader of the wide paver and the mechanical characteristics and gradation composition of the asphalt mixture were analyzed,and the force and movement of the asphalt mixture particles were analyzed,showing that the particle size,position is different,and its force and movement speed are different,resulting in the segregation of asphalt mixture,the wider the road width,the more obvious the lateral segregation phenomenon,thus affecting the paving uniformity.②The basic principle and basic equation of motion of the discrete element method were analyzed,and the Hertz-Mindlin with JKR model was determined as the particle simulation contact model.Relying on the physical engineering to obtain the main structural parameters and working parameters of the paver,the material parameters of different pavement structural layers are selected,and the wide asphalt mixture paver and the paving base surface are modeled in three dimensions.Complete the material property setting between particles,between particles and models,and between particles and paving surfaces;Pellet plant parameter setting;Motion parameter settings as well as solver settings.③The number of particles distributed in different regions and the sieve pass rate of different gradation compositions and segregation degrees were compared and analyzed,the mass proportion of particles of different sizes was calculated and solved,and the dissociation coefficient of mass proportion was determined As the uniformity evaluation index|Sc|,established the evaluation standard for the segregation degree of different grades of asphalt mixture.Based on the EDEM discrete element method,the uniformity of pavement paving under different working conditions was simulated and analyzed,and the results showed that:1)Under different paving conditions,most areas did not have segregation,and a few areas had slight segregation,and with the paving width widened The |Sc| value gradually increases slightly,and the paving unevenness trend increases.2)The conveying position of the spiral cloth where the mixture is located is different,the mass proportion of the difference coefficient is different,the paving uniformity is different,and the paver outlet area is |Sc| value is the largest overall,and the uniformity is relatively the worst;in the inlet area |Sc| Large,poor uniformity;Screw spreader support structure |Sc| slightly larger,slightly less uniformity;for other regions |Sc| is small,paving uniformity is better.3)When paving with the same paving width,using different gradation design upper limit,design lower limit,and design median value,use the gradation upper limit |Sc| Smallest,best paving uniformity.4)When different paving widths and the same thickness correspond to asphalt mixture graded paving,the paving thickness of 60mm and the use of AC-13 grade asphalt mixture particles are the best due to the relatively small particle size.④Based on digital image processing technology,the required particle feature parameters in the image are extracted,and through the four-sided static moment analysis of image particles,the binning-weighted four-sided static moment dissociation coefficient Cv is given as the measured paving uniformity evaluation index,and the acquisition image of the paving pavement of wide asphalt mixture is analyzed and calculated based on the physical engineering,and compared with the simulation test.The results show that the uniformity of paving of wide asphalt mixture pavement measured in the transverse direction is in good agreement with the uniformity law obtained by simulation analysis.