Study On Behavior And Repair Optimization Of Wheel Rut And Reflection Crack In Overlay Of Airport Pavement

The airport pavement in China is mainly cement concrete.In the middle and later stage of use,asphalt layer is paved on the old cement concrete slab to form a composite pavement.As a common repair scheme,it can effectively prolong the service life,but there will be new diseases.For the repair of main diseases of compound airport pavement,although there are many researches on wheel rut and crack diseases,there is a lack of systematic research on the overlay of airport pavement.Therefore,based on numerical simulation,this paper determines the main influencing factors of the disease and analyzes its mechanical characteristics and the influencing factors,while then optimizes the repair method.Firstly,this paper investigates and analyzes the diseases.The results show that the main diseases of airport pavement overlay are wheel rut and cracks,in which the wheel rut is mainly shear wheel rut and the cracks are mainly reflection cracks.Taking the Beijing Capital International Airport as an example,the takeoff and landing models are counted,and the grounding characteristics of different models are simplified based on FAA data.Secondly,taking the Beijing Capital International Airport as an example,this paper investigates the meteorological data and establishes the airport temperature field model in high temperature months.High temperature areas mainly appear in the upper layer,with the maximum temperature reaching 47.2 ℃.Based on the temperature field data and model investigation results,the temperature and load are analyzed respectively for the wheel rut disease.The results show that the influence of temperature on wheel rut is much greater than that of load.Furthermore,taking model 738 as the design model,the wheel load conversion based on wheel rut disease is carried out;Based on the FAA traffic coverage concept and the spatial distribution characteristics of axles of different models,according to the statistical data,it is determined that the maximum traffic coverage position of the airport pavement is 4.7m away from the centerline,and the maximum equivalent wheel load traffic coverage is 0.538.By coupling the airport pavement,temperature field and wheel load,and integrating the landing time distribution,wheel load conversion results and the interlayer contact state of cohesion model,a finite element model of airport pavement based on multi factor consideration is established.Then,for the repair of wheel rut disease,the mechanical characteristics are analyzed,and the parameter sensitivity analysis and optimization research are carried out for different factors and structural combinations.The main conclusions and optimization suggestions are as follows: in terms of materials,the repair quality can be improved by improving the modulus of asphalt layer,using epoxy asphalt concrete and ensuring that the bond strength is not less than 0.35 MPa when using local repair;In terms of structure,by appropriately reducing the total thickness of asphalt layer,or increasing the thickness of SMA layer and reducing the thickness of AC layer,and setting materials with better wheel rut resistance on the upper layer,the wheel rut resistance of the overall structure can be effectively improved.Finally,aiming at the crack disease,the repair method is studied,and the advantages of slotted repair method are analyzed.A refined three-dimensional finite element model with cracks and dowel bars is established.The results show that the main failure mode is shear cracking,and the repair of reflection crack at longitudinal joint is more unfavorable than that at transverse joint.Based on the indexes of shear stress,stress intensity factor and interface failure rate,the sensitivity analysis of material modulus,interface bonding strength,width,depth,angle and width ratio in slotted repair is carried out.It is suggested that the bonding strength of slotted repair interface should not be less than 0.3MPa,the slotting depth should not exceed 3cm,and the width depth ratio should fall between 0.8-2.Taking wheel rut and crack as the research object,this paper analyzes the stress characteristics of the disease based on finite element numerical analysis software,CZM cohesion model,temperature field theory,creep theory and fracture mechanics,and then systematically studies the repair optimization method,which provides reference suggestions for disease repair.