Research On Uniformity Computational Model Of Asphalt Mixture Under Three-dimensional Stress State

Asphalt pavement is the main form of highway in China.The pavement strength directly affects the durability of pavement structure.At present,the theory of maximum tensile stress or maximum tensile strain is often used as a failure index of asphalt pavement materials.Asphalt pavement structure is in three-dimensional stress state under load and environment,so the traditional one-dimensional strength theory can not reflect the real stress state of pavement structure.Therefore,This article carried out the following three aspects of research:(1)In this paper,the plane pressure/axial compression,plane is ostatic/axial tensile and plane tension/axial tensile test of asphalt mixture under different temperatures were carried out.The unified calculation model of asphalt mixture strength in three-dimensional stress state is established,which solves the problem of uncertainty of asphalt mixture strength.(2)The complex stress state strength model is simplified as the engineering application strength model,and the simplified parameters are verified by the test results of the tension,compression and splitting strength under the simple stress state,The results show that there is a good correlation.Considering the sensitivity of asphalt pavement to temperature and driving speed,this paper studied the destruction of the envelope of asphalt mixture with different temperature and different loading speeds,and established unified model of engineering application strength under different temperature and different loading speed.With the changes of temperature and loading speed,the destruction envelop is deflated according to a certain proportion in order to guide the engineering practice.(3)The typical asphalt pavement structures were selected to calculate the stress field in the structural layer based on the theory of elastic layered system.The shear stress at each point in the structural layer(τoct)divided by the shear strength of the octahedron(τ’oct)gives the coefficient K,which is used to determine the most vulnerable location.The calculation results show that the minimum value of K at the bottom layer F8(the midpoint of the single-circle load center and the single-circle load outer edge)is 7.9,which is the most destructible point of the whole upper layer,that is,Asphalt pavement design should focus on the stress state of the point.The failure modes of asphalt mixture are classified into oblique shear failure,columnar failure and pullout failure.