Research On Reflective Cracking Propagation Behavior In Asphalt Pavement Based On XFEM

Reflective crack is one of the main diseases of asphalt pavement in China.In this paper,the semi-circular bending test was carried out on the three types of asphalt mixtures(AC-20,AC-16,SMA-13)commonly used in the project.The fracture mechanics response of three asphalt mixtures was shown.Subsequently,with the help of extended finite element method and fracture mechanics theory,the semi-circular bending test of asphalt mixtures was numerically studied,and the anti-cracking optimization design of asphalt pavement structure was simulated and analyzed.In this paper,three asphalt mixtures(AC-20,AC-16,SMA-13)were prepared through rotating and compacting,and the semi-circular bending test samples were formed according to the specified size,and three cutting depths were set by manual cutting.They were 12 mm,15mm and 18 mm,and the width of the incision was 1.5mm.Three temperature conditions were set in the experiment,namely room temperature(25℃),medium temperature(15℃),and low temperature(-15℃).The load-displacement curve,failure process and failure form of the three asphalt mixtures under different temperature conditions were analyzed.It is concluded that the asphalt mixture has viscoelastic mechanical properties at room temperature and medium temperature,showing the characteristics of flexible failure,and showing the characteristics of brittle failure under low temperature conditions.From the perspective of energy,according to the evaluation indexes of fracture energy and fracture toughness in fracture mechanics theory,the paper comparatively analyzes the crack resistance of the three asphalt mixtures,and integrates the load-displacement curve of the semi-circular bending experiment.The envelope area is obtained,and after comparative analysis,SMA-13 has the highest fracture energy and fracture toughness,which is suitable for crack-resistant engineering materials in crack-resistant optimization design.In this paper,in order to verify the accuracy and effectiveness of the extended finite element method(XFEM)for simulating the propagation behavior of reflective cracks in asphalt pavement,a two-dimensional finite element model was established according to the true size of the semi-circular bending specimen,and three initial cut depths were set and assembled.They were 12 mm,15mm and 18 mm.The Prony series parameters converted from the dynamic modulus test were input into the model as the viscoelastic parameters of the asphalt mixture,and the fracture process of the semicircular bending test piece was simulated and calculated by using the extended finite element module of the ABAQUS finite element software.The loaddisplacement curve of the semi-circular bending specimen under controlled displacement loading mode was obtained.Comparing and analyzing the results of the specimen failure form,load-displacement curve and other results obtained by the laboratory and simulation,the conclusion that the simulation-experiment curve corresponded well was obtained,and the validity of the extended finite element method was verified to simulate the fracture shape and fracture process of asphalt mixture.The extended finite element method can be used as an effective simulation method for the crack propagation problem of asphalt pavement structure.This paper took the advantage of the extended finite element method in solving discontinuous problems such as crack propagation,used the extended finite element module of ABAQUS finite element software,combined the actual pavement engineering situation,obtained the geometric parameters and mechanical parameters of the actual road section and constructed a 3D model of cracked asphalt pavement.The crack ran through the entire road structure in width,and started at the bottom of the base layer and expanded upward.The actual effect of driving load was simulated by writing a DLOAD subroutine for moving load,and the propagation of reflective cracks under traffic load was calculated.Based on the fracture mechanics theory,the stress intensity factors SIFC,J integral and crack initiation angle at the crack tip were used as the fracture evaluation indicators.The asphalt pavement modulus,load field,vehicle speed,interlayer contact conditions,temperature conditions and other factors which influenced reflective crack propagation on asphalt were considered.According to the grey correlation theory,the influencing factors of crack propagation were quantified and sorted.Certain references and guides for the anti-cracking design and maintenance were provided.