Numerical Analysis Of Mechanical Response Of Asphalt Pavement Under Traction Semi-trailer Truck Based On Three-dimensional Continuous Finite-layer Method

Asphalt pavement structure has become the main pavement structure of highways including expressways.Many countries in the world use the Mechanistic-Empirical Pavement Design Guide to carry out the asphalt pavement structural design,in which the mechanical analysis needs to be used as a calculation method and a mechanical model,which can reflect the structural characteristics of the layered asphalt pavement as true and objectively as possible.With the development of automobile transportation,as a kind of artic,semi-trailer truck has been got more and more attention because of the advantages of large transportation,high transportation efficiency,low transportation cost and so on.But this kind of vehicle has its own structure especially(traction locomotive and semi-trailer connected by hinged way).Compared with ordinary single rear axle and double rear axle truck,its working state is more complex.For example,in the process of braking deceleration,The semi-trailer load will have a non-negligible influence on the front tractor due to the vehicle dynamics effect.It may cause worse and special damage to pavement structure.This paper attempts to analyze the mechanical response of asphalt pavement structures under semi-trailer truck loads by using the three-dimensional continuous finite-layer method,which has attracted much attention in recent years.The main work has been carried out as follows:(1)The fundamental principle of 3D continuous finite-layer methods is introduced,including fundamental assumptions,load treatment,fundamental equation,moving single harmonic wave and single layer solution,boundary condition,etc.Combined with the 3D-Move Analysis software which based on this method,the 3D continuous finite-layer method's refined simulation advantage applied in the complex traffic load,the viscoelastic asphalt pavement and other aspects are described.Thus,it lays a foundation for the analysis of the structural mechanics of asphalt pavement.(2)Foreign typical asphalt pavement structural mechanics analysis software,BISAR,MICHPAVE,Ever Stress FE and 3D-Move Analysis are compared from the principle algorithm,specific implementation and so on,and in accordance with a specific example,the relevant discussion is carried out to provide useful reference for the rational selection of tools.(3)This paper introduces the construction principle of the 3+2 semi-trailer truck and the calculation principle of the normal force and tangential force of each axis during downhill braking and deceleration considering vehicle dynamics.According to a specific example,the force acting on the brake deceleration of the semi-trailer truck is solved,and the influence of the change of the acceleration and the road longitudinal slope on the normal load and tangential load of each axle is analyzed.Laid the foundation for the mechanics response load analysing of the pavement structure under the action of the semi-trailer truck under different working conditions.(4)Based on the 3D-Move Analysis software,the three-dimensional numerical model of the flexible base asphalt pavement structure under the load of single axle double wheel load and semi-trailer truck load is established respectively.The mechanics response of the two kinds of load forms in the flexible base asphalt pavement structure under different working conditions is analyzed,and The variation of the time history under the uniform velocity and braking reduction conditions are clear.The difference of mechanical response of pavement structure under the load of semi-trailer truck and single axle double wheel is compared.(5)Based on the 3D-Move Analysis software,considering the viscoelastic of the asphalt surface and the braking characteristics of and semi-trailer truck,the semi-rigid base,upside down and combined asphalt pavement structure numerical models are set up respectively.The change law of the mechanical response in the braking deceleration process of the semi-trailer truck is analyzed,The effects of acceleration and pavement temperature on the mechanical response of three asphalt pavement structures are discussed.and the applicability of the three asphalt pavement structures is explored in the frequency sections of semi-trailer truck deceleration and braking.The results obtained in this paper have a certain engineering guiding significance and practical value for enriching the analysis method of asphalt pavement structure,mechanical model,and ensuring the excellent use of asphalt pavement in high grade highway section with high traffic volume of semi-trailer truck.