Study On Cracking And Creep Behavior Of Heterogeneous Asphalt Mixture Based On Discrete Element

Asphalt mixture is a multiphase composite system with both distinct particle characteristics and nonlinear mechanical characteristics.The current research on asphalt mixture is based on the numerical simulation method based on continuum mechanics theory,and is not suitable for exploring the micro and micro essence of asphalt mixture by means of laboratory test or engineering test road.Moreover,the theory of continuum mechanics is mainly based on the basic assumption of uniform,continuous and small deformation,which is not suitable for describing the asphalt mixture,and can not analyze the mechanical properties of asphalt mixture in the micro scale.Discrete element method is a numerical simulation method is used to study the mechanical behavior of special particle materials,asphalt mixture can be quantified by internal loading in the process of stress,can consider the anisotropic characteristics of asphalt mixture of asphalt and aggregate,and can better simulate the effects of aggregate size and distribution the shape,gradation,and other factors on the performance of material for asphalt mixture virtual test analysis and micro structure analysis provides a new solution to solve the deformation.Based on discrete element analysis,combined with experimental research method to determine the transformation parameters and macro model of micro parameters in theory,discrete element model parameters,and then establish the discrete element model of asphalt mixture,through the numerical simulation of the asphalt mixture of the cracking behavior and creep behavior,open up new the way for the study of asphalt mixture material cracking mechanism and creep characteristics,has important theoretical value and broad application prospect.First,the corresponding relationship between meso model parameters and asphalt mortar and aggregate macro parameters is deduced,and other meso parameters such as particle size and parameters between asphalt mortar,mortar aggregate,aggregate and aggregate aggregate are determined.Through the creep test and curve fitting of asphalt mortar,four parameters in the corresponding Burger's model are obtained,and then the viscoelastic parameters in the discrete element model are obtained.Secondly,on the basis of this,a two-dimensional semicircular bending digital model and a 3D creep prism model based on the boundary condition and servo control of the real test are established.The generated discrete element virtual specimen can maximize the aggregate gradation,the irregular shape of the aggregate,the random distribution of the aggregate and the porosity of the specimen.Moreover,the 3D creep model takes into account the viscoelasticity of asphalt mixture,and proposes a simulation method that can be separated from indoor test conditions and can be used to map asphalt mixture accurately and widely with PFC software.Finally,based on the discrete element model of semicircle,the influence of factors such as maternal particle,porosity and bond strength on the cracking behavior of asphalt mixture is studied.On the basis of the three-dimensional creep discrete element model,the parameter sensitivity analysis of the creep behavior of asphalt mixture is carried out.To explore the effect of stress level,coarse aggregate,mortar and homogenization homogenization temperature on creep behavior,provides a new way for the study on the cracking mechanism of asphalt mixture material and creep characteristics,combined with laboratory tests for future work to provide a theoretical analysis and some basic data on the mechanical properties of the asphalt mixture.