Research On Structural Stress And Arching Effect Of Asphalt Pavement Based On Discrete-Continuous Coupling

The current design specification adopts the multi-layer elastic continuous system theory.It regards the asphalt pavement as a continuous medium,but does not consider the influence of the asphalt mixture material composition on the stress calculation results.The asphalt mixture is a multiphase composite material composed of aggregate,asphalt and voids.The skeleton network formed by the mutual embedding of aggregate particles and the unique arching effect of the particulate matter will affect the calculation results of the pavement stress.Therefore,the stress calculation method of the current design specification still has shortcomings.In this paper,a discrete-continuous coupled asphalt pavement model is constructed based on the discrete element method and the finite element method.The model not only reflects the actual boundary conditions and stress state of the asphalt pavement,but also considers the microstructure and particle characteristics of the asphalt mixture.Then,based on the stress ratio and other parameters,the influence of load properties and asphalt mixture properties on the static stress of asphalt pavement was studied.It proves the arching effect in asphalt pavement.This effect will cause a deviation between the central stress of the road surface and the theoretical value,the difference between the two is about 10%.Among them,the gradation and load width have a greater influence on the arching effect.At the same time,the stress state of asphalt pavement under dynamic load is studied.The dynamic stress response of asphalt pavement can be divided into three stages.The three stages are stress smoothing stage,stress sudden increase stage and stress dissipation stage.The similarities and differences between the coupling model and the theoretical value are compared and analyzed based on the key point positions of the three stages,the peak stress ratio and other indicators.The hysteresis of the stress peak point and the peak stress change caused by the arching effect are verified.It is found that the load sensitivity of the asphalt mixture is greater than that of the continuous medium.The degree of arching effect of asphalt pavement under dynamic load is slightly less than that of static load.The main reason lies in the instantaneousness of dynamic load.The load weight and gradation have a greater influence on its stress.In addition,a movable door test device for mineral mixtures was developed,and raw materials and experimental parameters were optimized based on the drop rate index.The degree of arching effect of different graded mixtures was evaluated.The degree of arching effect of the densely framed mixture was greater than that of the suspended dense type.Among them,the degree of arching effect of the SMA-16-graded mixture was the largest.This equipment can provide a practical tool for detecting the arching effect of graded mixtures.Generally speaking,this paper combines the research results of numerical simulation and mineral mixture movable door test,and has a preliminary understanding of the influence of arching in asphalt pavement on the results of stress calculation,which provides a reference for the further improvement of stress calculation methods.