Finite Element Analysis Of Boundary And Size Effect Of Asphalt Mixtures

With the continuous improvement of infrastructure,the demand for road construction is also increasing.This has led to an increase in the mileage of the road and a further demand for road quality at the same time.Asphalt mixture is an important raw material in the entire road construction process.Therefore,by studying the dimensions and loading boundary conditions of the asphalt mixture specimen itself,it is necessary to propose a suitable specimen size for analyzing the mechanical properties of the asphalt mixture.In this paper,the finite element analysis method is mainly adopted.Firstly,the cylindrical asphalt mixture specimen is simulated.Based on the uniaxial compression test in the current specification,the height of the specimen,the size of the hollow radius,the thickness of the rigid plate and the confining pressure are studied.The influence of specimen size results in a more appropriate thickness of the rigid plate,the size of hollow cylindrical,and the proportional coefficient of stress between different confining pressures.At the same time,the relationship between the height of the prismatic specimen and the thickness of the rigid plate was analyzed,and the feasibility of the height of the specimen used in the specification was verified.Secondly,the meso-mesh model was established using the self-developed asphalt mixture meso-structure model program,the asphalt mixture model is divided into coarse aggregates,fine aggregates,asphalt binders,and independent voids.By controlling the single variable principle,the parameters of the materials are assigned to the analysis.It was concluded that the skeleton structure formed by coarse aggregate is the main bearing part of the whole mixture.With the increase of the coarse aggregate modulus,the displacement has a power index decreasing trend,while the change of the fine aggregate and the asphalt mortar modulus has a small impact on the displacement and force of the specimen.The time-course analysis shows that the viscoelasticity in the mixture is mainly reflected in the asphalt binder part.Finally,an indoor experiment was performed on prismatic specimens with different thicknesses.The influence of dimensional changes on the test was analyzed.Combined with the finite element simulation results,it can be obtained that when the specimen thickness is greater than 25 mm,the effect of thickness variation on the specimen displacement can be ignored.