Study On Mesoscopic Digital Model Of Asphalt Mixture And Numerical Test

Coincident with the continuous improvement of science and technology has been a growing research ranging from macroscopic to microcosmic or mesoscopic on asphalt mixture,a kind of composite material made up of asphalt mortar,coarse aggregate and void.Current research on asphalt mixture-a heterogeneous material-is mainly concentrated on the macro level.Micromechanical model is,by combining macroscopic mechanical parameters and internal mesoscopic mechanics characteristics,established and the mechanics simulation experiment research is conducted in order to get its internal mechanical mechanism,thus according with actual situation.In this paper uniaxial compression tests of mother rock specimen which are respectively corresponding to bituminous mortar,AC-13 asphalt mixture and coarse aggregate,through WDW-300 Euniversal testing machine and TAW-2000 rock triaxial apparatus,at room temperature,are conducted for the purpose of obtaining the modulus of elasticity and Poisson's ratio.Meanwhile,the elastic modulus of asphalt mortar is modified and the material parameters of the bonding interface is estimated reasonably,thus providing material parameters for the finite element numerical analysis.Formula coefficient determined by theoretical formula and related research,the number of the particle size aggregate of the AC-13 is calculated in combination with AC-13 synthesis gradation,which provides data support for mesoscopic geometrical model of two-dimensional asphalt mixture.Based on the stochastic theory,in consideration of such randomness as position and aggregate shape of mesoscopic geometrical model,the size of the bonding interface along with generation method is determined.Running results of MATLAB is achieved by introducing the counter,by controlling benign operation of program and by adding AUTOCAD drawing commands.One-click drawing is performed in AUTOCAD,on the basis of which the problem of the link between the finite element software and MATLAB is solved.Finally,the internal deformation law of the asphalt mixture is,by means of numerical simulation,acquired,which confirms the necessity of the mesoscopic structure simulation for bituminous mixture.Results show greater stress and strain than the macroscopic load can occur in the local position inside asphalt mixture on condition that external load has not yet reached its macroscopic damage and that the main destruction locates in the second defined contact interface which is 0.012-0.024 mm away from the aggregate.Coupling effect appears in different angularity position as a consequence of stress concentration phenomenon of coarse aggregate angularity,but the law in the second and third interfaceis is relatively stable.It is the content of coarse aggregate within specimen that can also affect its deformation.The research achievement provides a new access to the virtual mechanical test simulation study and simultaneously provides favorable basis for the engineering practice including the gradation design of asphalt mixture,the choice of aggregate content,prismatic characteristic of aggregate by screening,the strength ascension of destruction interface and the evaluation on the biggest bearing capacity of pavement.