| With the development of urbanization in China,the volume of traffic on urban roads is increasing,and rutting has become a serious problem in urban roads.As the main road intersection is a city traffic hub,the traffic coming and going through the intersection is slow and brakes frequently,so the intersection pavement rutting disease is more serious compared with the main line section.Frequent semi-closed maintenance and reconstruction of intersection area pavement not only causes traffic jam,but also consumes a lot of financial and material resources.As a result,analyzing and preventing intersection rutting is critical to the structural design and maintenance of intersection asphalt pavement.This paper is based on the survey of the current situation of urban trunk road intersection pavement in Taian City,the causes of intersection pavement rutting are analyzed by finite element,in-depth rutting disease prevention and control research,optimization of asphalt mixture grading design method,and verification of prevention and control effect by discrete element,which mainly includes the following four aspects:(1)Investigate the current situation of urban trunk road intersections in Taian.Investigate the traffic situation of some trunk road intersections in Taian,calculate the traffic volume and axle load at the intersections,and also investigate the typical pavement structure and pavement diseases to provide data support for ABAQUS finite element analysis.(2)To explore the causes of intersection rutting.ABAQUS was used to simulate the summer temperature field of a typical pavement structure in Taian City,and establish the mechanical response model under temperature field and permanent deformation model under continuous temperature change.The effects of different horizontal load factors on the mechanical response of the pavement are analyzed,and the mechanism of rut formation is summarized by combining the permanent deformation of the pavement under different speeds and different horizontal load factors.The upper layer is determined as the primary rutting resistance zone based on the location of the pavement structure’s maximum shear stress distribution and the permanent deformation of each layer,which provides guidance for the next prevention and control measures.(3)Gradation design of high Anti-shear asphalt mixture.Based on the stage filling theory and the shear modulus formula of bulk material,the composition of SMA-13 gradation for typical pavement structure is optimized by improving the shear resistance of the upper layer as a means of prevention and control,and the optimum oil to stone ratio is determined according to the Marshall test to design a high shear resistant asphalt mixture gradation MAS-13(Multilevel Anti-Shear grading).The shear property of the two gradations was contrasted using a uniaxial penetration test,and the road performance was evaluated using a rutting test,a freeze-thaw splitting test,a water immersion Marshall test,a structural depth test,and a water penetration test.(4)Construction of a discrete element asphalt mixture virtual rutting test.According to the cross-section photos of rut specimen,the virtual rut specimen modeling of two asphalt mixtures was completed by using PFC2 D.The model is validated through modeling of an indoor rutting test.According to the results of the indoor virtual rutting test,a virtual rutting test under horizontal load was performed to extract the contact force between the aggregates and the contact force between the asphalt mastic in the two asphalt mixtures,and analyze the prevention and control effect of MAS-13 application at intersections on rutting disease.The research in this paper shows that the large shear stress caused by vehicle braking is the main reason for permanent deformation of the intersection pavement.High temperatures and lower traffic speeds exacerbate the development of rutting at intersections.Optimizing the gradation using stage filling theory and a bulk material shear modulus calculation formula not only enhances the strength of shear and shear modulus of the asphalt mixture,but it also has excellent high temperature stability,water stability,skid resistance,and seepage resistance.Finally,after PFC2 D verification,compared with SMA-13,MAS-13 formed a stronger skeleton of coarse aggregate,and the asphalt mastic had greater stiffness.MAS-13 produces less vertical deformation and horizontal deformation under load,and can be applied to the top layer of intersections to reduce pavement rutting. |
