Research On The Structure Of Asphalt Pavement With Granular Transition Layer

Because of fine strength and fatigue resistence, semi-rigid base asphalt pavements are widely used in paement structures of heavy-traffic road in our country and overseas, lots of cases show crack is the main disease of semi-rigid base asphalt pavement and the cause of early occurrence of diseases of asphalt pavements of highways. After graded broken stone is provided weth excellent drainage, dispelling reflection cracking function and fine economics understand, flexible pavement structure weth graded broken stone base will become an important structure of high-graded road pavement which is diversification developing in the future. Based on that, the paper researches on the pavement structure of graded broken stone transition layer as follow.Firstly, the paper introduces physical indexes of the material and does basic performance test, based on the screen test the paper does mix design, the influencing factors of basic mechanical behaviour of graded broken stone are analyzed.Secondly,based on fracture mechanics and ABAQUS finite elements software, the paper calculates the stress intensity factor of pavement structure of graded broken stone transition layer and semi-rigid base pavement structure,and analyzes the influence of change of modulus and thickness of the layer of graded aggregate,modulus of surface and semi-rigid base on stress intensity factor.The results indicate that the layer of graded aggregate can reduce the stress intensity factor of the subbase and prevent reflection cracking effectively and slow down the expansion of reflection cracking effectually. It can improve the effect of preventing the reflection cracking with the layer of graded aggregate by suitable increasing the modulus and thickness of the graded aggregate base and the modulus of semi-rigid base.The force of the pavement structure with graded broken stone transition layer is analyzed based on ABAQUS finite elements software and different parameters of the structure, the influence of parameters on the force analysis is studied,which will theoretically support the design of structure mix,and then the paper presents several kinds of pavement structure of graded broken stone transition layer bases theoretically, which suit the Liaoning regional.Theoretical analysis shows that the addition of graded broken stone transition layer is re-assignment of the stress and strain in the pavement structure, as the thickness of graded broken stone layer increases, deflection and tensile strain tend to increase,but the the stress intensity factor of surface tends to decrease which based on fracture mechanics,so this paper recommends the thickness of graded broken stone layer is from 10cm to 15cm.Enhancing the modulus can reduce the deflection, tensile strain,stress of semi-rigid base and vertical compressive strain of earth base,so it is very important to enhance the modulus of graded broken stone.The major factors which affect tensile strain of surface are the modulus and thickness of asphalt pavement and thickness of graded broken stone transition layer. It can reduce the disadvantageous factor such as stress and strain by increasing the thickness of asphalt pavement, economic conditions in the permit conditions, suitable increasing the thickness of asphalt layer to improve the condition of structural behavior.At last, the paper presents several kinds of pavement structure of graded broken stone transition layer bases that suit the Liaoning regional by comparing with the actual measurement date of different pavement structural test roads and analysing the cause,which not only provide the technology data for application and dissemination of the asphalt pavement structure with graded broken stone transition layer,but also change the single pavement structure in our province.