Three-dimensional Dynamic Response Analysis Of Asphalt Pavement Structure Under Moving Load

The multi-layered structure is a common structure in nature and artificial environments.In the road engineering,pavement structure is also regarded as a multi-layered structure.Due to the differences in construction technology and pavement materials,each structure layer presents obvious transversely isotropic characteristics.In addition,the load acting on the soil layer and pavement structure is not completely static load.The vehicle load mostly exists in the form of moving load.Due to the unevenness of the structure surface and the vibration of the vehicle itself,the load moves on the structure surface with a certainly natural frequency.Therefore,the layered isotropy theory and double circular uniform static load adopted in pavement structure design in China can no longer well represent the actual situation of pavement,which has obvious limitations.In this paper,based on the layered elastic theory,combining Cauchy stress principle and finite element theory,and considering the contact state between layers,the expressions of the 3D homogeneous isotropy and3 D transversely isotropic structure under rectangular moving harmonic load are established respectively.Then the influence of load parameters and structure layer parameters on the dynamic response of the pavement structure is analyzed.The details are as follows:(1)The 3D dynamic response of the layered isotropic structure under a rectangular moving harmonic load is studied by Spectral Element Method.The effects of load speed,load frequency and interlayer condition on the dynamic response of the layered isotropic structure are analyzed.The results show that when the velocity is not very high,with the increase of moving speed and the decrease of load frequency,the deflection of the road surface increases gradually.The tensile strain at the bottom of asphalt pavement and the vertical compressive strain at the top of soil foundation both increase with the increase of moving speed,but the influence of frequency is limited.The deterioration of the contact mass between layers will obviously increase the three dynamic response indexes and accelerate the destruction of the structure.(2)Spectral Element Method is applied in the 3D dynamic response analysis of layered transversely isotropic structure under a rectangular moving harmonic load.In addition,the effects of load speed,load frequency,transversely isotropic characteristics of the surface layer and the interlayer condition between layers on thedynamic response of the transversely isotropic structure are analyzed.The results show that the smaller of the transversely isotropic coefficient of the surface layer,the larger the deflection of the road surface,the tensile strain at the bottom of the surface layer and the vertical compressive strain at the top of soil foundation.The deterioration of the contact mass between layers will aggravate the structural damage.Moreover,the influence of frequency on the three dynamic responses is weaker than that of speed.The theoretical research and its results in this paper can provide some reference value for the design theory of pavement in China,and also play a certain role in promoting the development of the pavement mechanics.