Study On Paving Uniformity Of Wider Asphalt Pavement And Compaction Characteristics Of Pavement Base With Large Thickness

Semi-rigid base is the main structure of high-grade highway pavement in our country.In the actual construction process,it is generally divided into two layers for paving and rolling.The main problems caused by stratified compaction are: poor integrity,long construction period,easy occurrence of early damage at the grassroots level,increase of project cost,and mutual reflection of cracks at the upper and lower levels.The pavement construction technology of wider and large thickness pavement is a new type of construction technology.Compared with the traditional multi-layered paved way,the technology has the advantages of maintaining the integrity of the pavement,avoiding the seam of the machine,simplifying the pavement construction process and saving construction period and construction costs and other advantages.At the same time,it can be seen that there are few researches on the technology at home and abroad,and there is lack of systematic research on the horizontal segregation control of the wider asphalt pavement construction and the compaction control of large-thickness cement stabilized stone base,which restrict the popularization and application of the technology.In response to the above problems,the following research works are mainly carried out:(1)Based on the orthogonal test method,the simulation scheme design is carried out.The EDEM discrete element method is adopted to simulate the paving process under different screw distributor parameters of wider paver,and then the repeatability standard deviation of pavement density is introduced to evaluate the pavement uniformity.The influence of the parameters of the screw distributor on the uniformity of the pavement is obtained,and the parameters of the spiral distributor are optimized.Finally,the correctness of the simulation analysis is verified by the field test.(2)Proceeding from the interaction between the material and the screw during the distributing process,the dynamics and kinematics analysis of the mixture in the screw distributor are carried out.And the segregation mechanism of the wider paving is analyzed.The mathematical model of the relationship of structural parameters,using parameters and material parameters is established,then the main structural parameter determining the paving uniformity was obtained as the radius-center distance ratio(the ratio of the screw shaft diameter to the pitch)through analyzing the influence of the parameters on the performance of the screw distributor,and the range of the value was given.Meanwhile,a material level height model,a screw blade material conveying capacity model,and an integer-integer linear programming model with the equal-pitch and ladder-type variable-pitch screw are established.And the disposition of blades with different diameters on the equal-pitch step-type variable-pitch spiral screwdriver when the height of material level and the flow rate are satisfied is proposed,which provides a reference for the screw design and engineering application of wider paver.(3)The ANSYS software is used to analyze the difference of mechanics and fatigue properties between the wider and large-thickness paved way and the multi-layered paved way of the cement stabilized stone base.And the influence of the inter-layer bonding state on the service performance of cement stabilized stone base is studied through indoor test.The performance advantages of the wider and large-thickness paved way are analyzed.Then,the compaction process for large-thickness cement stabilized stone base is formulated.(4)The compaction process of different tonnage rollers is analyzed using ANSYS software,and the attenuation law of roller's compressive stress as a function of road surface depth is analyzed.Then the feasibility of compaction of the large-thickness cement stabilized stone base is theoretically analyzed.Based on the principle of "compressive stress equivalence",the matching model between the tonnage of the vibratory roller,the compaction time and the compacted thickness of the cement stabilized stone base is obtained,which provides a theoretical basis for the selection of vibratory road rollers and the formulation of compaction technology of the large-thickness of water stability.Meanwhile,combined with field test,the correctness of numerical simulation and the practical compaction effect of the large-thickness cement stabilized stone base are analyzed.Theoretical analysis and field tests show that the research results of this paper can effectively solve the key issues such as horizontal segregation of wider asphalt pavement and compaction degree control of large-thickness cement stabilized stone base,whicn provides a theoretical basis and technical support for the practical engineering application of the wider and large-thickness pavement construction technology.