Reconstruction Scheme And Structure Optimization Of Heavy Load Asphalt Pavement

Currently,asphalt pavement is the main pavement structure form of high grade highway and urban main road in China.However,with the heavy load and high speed of highway transportation,asphalt pavement is easily damaged and can not reach the expected service life.Therefore,the improvement and transformation of damaged asphalt pavement structure is worth studying in the field of road engineering.Aiming at the upgrading and rebuilding project of a heavy load and fast road in Xiamen,combining with the local climate and load conditions,the ABAQUS finite element software and the KENPAVE layered system pavement calculation program are used to establish the semi rigid base,RCC mixing base and ATB-25 combined base asphalt pavement structure,a total of 5 kinds of 3 types of asphalt pavement structure model.From three aspects of temperature action,comprehensive effect of temperature and moving load and damage mechanics life analysis,the numerical analysis of structural optimization in the process of asphalt pavement improvement is carried out,and the dynamic mechanical response and damage life of different types of pavement structures under the actual load conditions are analyzed and studied.The main work is:Based on the theory of heat transfer,the temperature distribution of the pavement structure under high and low temperature in 24 h is calculated.On this basis,the temperature stress is calculated and the influence of the interlayer bonding state on the distribution of the temperature stress is analyzed.Based on the theory of viscoelasticity and dynamics,the influence of axle load,vehicle speed and interlayer bonding state on typical dynamic response indexes of different pavement structures is analyzed and calculated.Based on the theory of fatigue cracking and permanent deformation damage,the damage control modes of different structures are analyzed,and the service life of different structures is predicted.The main conclusions are as follows:(1)The total solar radiation,daily average wind speed and sunshine time are the main factors affecting the temperature field distribution of asphalt pavement structure,and the influence of the 3 factors is reduced from front to back.The temperature change in the surface layer,especially the upper layer,is the largest and the change of the base layer and the following structural layer is relatively small.The trend of temperature stress in all structural layers is closely related to atmospheric temperature.The greater the temperature gradient is,the greater the temperature stress is.The base layer is the most obvious pavement structure layer caused by temperature change,and the surface stress of subbase and soil foundation is smaller.(2)There is a similar linear growth relationship between the maximum of dynamic mechanical response and the load size,and a similar linear reduction relationship with the speed of the vehicle,and the change rate is related to the structure layer and the temperature condition,but the variation of the minimum value with the size of the load and the speed of the vehicle is more complex and has uncertainty.In the 5 structures,the mechanical properties of the structure 2,the RCC mixed base pavement,are the best,the mechanical properties of the structure 1 and the 5,the semi-rigid base pavement,are the worst,and the mechanical properties of the structure 3 and 4,the ATB-25 combined base pavement,are in the middle.(3)Increasing the thickness and strength of the base is helpful to improve the ability of the asphalt pavement structure to resist fatigue and crack and permanent deformation,and to improve the service life of the pavement structure.The strength of the first structural layer under the underlayer of asphalt will directly affect the size of the bending strain of the asphalt layer,which has a great influence on the fatigue life of the whole pavement structure,and improving the strength of the asphalt layer is beneficial to the improvement of the fatigue life of the asphalt layer.With the increase of axle load,the damage life of asphalt pavement structure is obviously reduced,and the speed has little effect on the pavement damage performance.In the 5 structures,the damage life of structure 2 is the longest,and the damage life of 1 is the shortest.