The Study On Cracking Of Asphalt Pavement Based On The Extended Finite Element Method

Asphalt pavement,usual y subjected to repeated actions of the external environment and vehicle loads for a long time,is prone to cracking.Once cracked,the continuity and integrity of the asphalt pavement structure will be severely damaged.Therefore,the research on cracking of asphalt pavement has important guiding significance for the design,construction and maintenance of asphalt pavement.The existing research is mainly based on mechanical methods,revealing the cracking characteristics of cracks through the use of mechanical indicators,and then analyzing and predicting the cracking and crack propagation.Many research results with great depth and influence are based on this.However,this research method must assume that the crack does not crack and spread,which not only affects the results of the study,but also is inconsistent with the actual project.In order to solve this problem,based on the extended finite element method and combined with numerical simulation methods,the asphalt pavement model was established to achieve the crack propagation of asphalt pavement cracks,revealing the cracking behavior of asphalt pavement more profoundly,and providing technical guidance for engineers to provide pavement design and maintenance.In this paper,the main research works as following:(1)In view of the temperature crack propagation characteristics of asphalt pavement in subtropical oceanic monsoon climate regions under wheel load and temperature,relying on the reconstruction project of Haixiang Road in Xiamen City,Fujian Province,the asphalt pavement model with a single transverse thermal crack was established,and the surface cracks were analyzed within 24 hours.Under the temperature load,the crack propagation characteristics show that the horizontal cracks on the road surface mainly undergo type I crack propagation under the temperature load.The most severe cracking time is at 24 o’clock.The cracking conditions are more severe in winter than in summer.Secondly,the typical temperature field is studied.The propagation characteristics of cracks under moving loads show that,under the coupling of temperature and load,the main cracking form of transverse cracks on the surface is type II shear expansion,and the most unfavorable moment is still at 24 hours;based on the above research results,The crack resistance performance is a criterion for the optimization of the reconstruction scheme,and the optimal structure is the structure 4.(2)Aiming at the problem of crack propagation on the Top-Down surface under uneven settlement,the finite element model based on the extended finite element method was established by means of numerical simulation.Through calculation and analysis,it was found that crack cracking and expansion is an extremely complicated process.The occurrence of the expansion is sudden;secondly,it focuses on the influence of uneven settlement value,crack initiation position,and traffic load on the process of crack cracking and expansion.According to the research results,the increase of the uneven settlement value will increase the crack propagation.Degree;When the cracks are offset,the increase of the offset value will increase the degree of crack expansion and then reduce;In the aspect of traffic load,the extent of crack propagation decreases with the increase of driving speed,and aggravates with the increase of axle load value.The position of the load acting on the crack propagation is extremely complicated.(3)Aiming at the multi-crack compound cracking behavior of semi-rigid base asphalt pavement,based on the extended finite element method,a finite element model of a semi-rigid base asphalt pavement with two longitudinal cracks was established.The crack splitting and initial crack length crack cracking were analyzed.Impact.The results show that the interference effect between the two cracks will affect the composite crack propagation,and this effect will weaken with the increase of the crack spacing.The increase of the crack spacing will weaken the degree of crack propagation of the side crack,and cause the center crack cracking.The degree is weakened after being aggravated;when the crack length increases,the degree of crack propagation increases first and then decreases,while the crack propagation degree of the other crack continues to decay.