The Research On Shear Numerical Simulation And Virtual Test Of Asphalt Mixture

With the change of traffic structure and the increase of traffic volume,axis load and traffic channelization,some new diseases such as rutting,pushing,shoving package and load type cracking have happened on the asphalt pavement.The reason of occurrences of these diseases is the lack of shear performance of asphalt pavement.Currently,the seriousness of the shear failure have been recognized by many academics.The shear performance of asphalt mixture has been studied by them.However,the indoor macro test level have been mainly concentrated,these methods are not only labor-intensive and time-consuming,but also are difficult to study the failure process of the mixture from meso-scale.Therefore,the discrete element method is used to analysis the shear performance of asphalt mixture from meso-scale in this paper,and the main works are as follows:Firstly,on the basis of previous studies,a new algorithm for generating irregular aggregates was improved,and the corresponding numerical model of asphalt mixture was generated.At the same time,the numerical model of the standard fourteen surface shape and spherical aggregate particles were also generated by changing the shape of the aggregate base on it.In addition,for the two-dimensional model,the numerical model of the asphalt mixture with irregular polygonal aggregate particles and the numerical model with hexagonal and circular aggregate particles were generated,which lay foundations for the follow-up research.Secondly,the characteristics of several common microscopic parameters in PFC were analyzed.Moreover,combined with the characteristics of different materials in the asphalt mixture,the micro models which could reasonably reflect the mutual contact behaviors were chosen base on them.The principle of density division which could provide a method for parameter assignment was proposed.In addition,the relationships between macro and micro parameters were analyzed.Thirdly,the virtual torsion test method of asphalt mixture was established by using discrete element software.The simulation of torsion test of asphalt mixture was carried out.Then,according to the torsion test of asphalt mixture,the results show that they have high consistency.Fourthly,in order to analyze the shear failure characteristics of asphalt mixture intuitively,the cylinder model of simple shear test was simplified into a two-dimensional rectangular model,and a numerical simulation test method of two-dimensional constant height simple shear was established.The two-dimensional simple shear at constant height numerical simulation was carried out,and the change of stress and the development of cracks were analyzed.Finally,according to the numerical simulation methods of torsion test of asphalt mixture and constant height simple shear test of asphalt mixture,shear performances of asphalt mixture were studied on aggregates and voids.The relationships between shear strength and aggregate and voids were analyzed which provide a reference for revealing the shear failure mechanism of asphalt mixture.