Study On Stress And Deformation Characteristics Of Layered Asphalt Concrete Structure Under Complex Loads

In recent years,the paving of asphalt concrete pavement in our country is becoming more and more extensive,and the highway,first grade highway and urban road are mostly asphalt concrete pavement.This is due to the asphalt concrete road masks have good mechanical properties,smooth and wear-resistant surfaces,comfortable driving performance,and good construction work ability.However,the rapid growth of highway traffic volume,the formation of channelized traffic,the continuous increase in vehicle axle loads,and the phenomenon of heavy overloading have continued.This has led to more serious problems in the early destruction of asphalt concrete pavement,and rutting is one of the main diseases.Although domestic highway technicians have done a lot of experimental research on Asphalt Mixture’s high temperature characteristics and achieved many valuable research results,overall,the early damage problem of high-grade asphalt concrete pavement in China is still prominent.At present,in most of the pavement structure design of our country,the standard axle load BZZ-100 has been used in the specification.However,this load is not changed at the design time,and it does not truly reflect the characteristics of vehicle load changes and the actual effect of the road pavement on the load of the vehicle.In this paper,through selecting the actual vehicle model and taking the BRT asphalt concrete pavement structure in Yichang as an example,by analyzing the mechanism of vehicle loading,a three-dimensional finite element model is established to study the stress and deformation characteristics of the pavement under the load of vehicle.First,the asphalt mixture design experiment was carried out,and the load on the asphalt concrete pavement during the static and mobile process was analyzed.Because of asphalt concrete exhibits different material properties under different temperature conditions.In this paper,the elastic constitutive model and creep model are used to calculate the total deformation of asphalt concrete pavement under different vehicle loads.Comparative analysis of pavement displacement and stress under different conditions,especially vertical deformation and horizontal shear stress,the study shows that:(1)When the temperature of asphalt concrete is low,the elastic constitutive model can be used to calculate and analyze,and when the temperature is too high,the softening phenomenon obviously occurs.(2)In the static state,the vehicle will mainly generate vertical loads on the road pavement,vertical deformation will occur on the road pavement,and the emergency stop or acceleration during the movement will cause the increase of the horizontal load,the total deformation of the road pavement will increase continuously,and the upward trend will be obvious,which indicates that the horizontal load has a larger effect on the overall deformation of the pavement.As a result,the shear caused by the shear effect plays an important role in the destruction of the road pavement.(3)From the results of the total deformation of the road when the vehicle starts and decelerate,it can be seen that when the horizontal load is fixed,the total deformation when the vehicle is started is slightly larger than that of the deceleration state.(4)The maximum shear stress distribution is mainly distributed at 5cm to 13 cm below the road surface,and appears in the middle surface layer.This is because the position of the middle surface is most complex,and it is in the three direction complex stress state,which is more likely to cause damage.