Study On Shear Resistance Of Asphalt Mixtures Based On Three-Dimensional Discrete Element Method

Asphalt mixtures is an anisotropic heterogeneous composite material. The discontinuity between particles makes it difficult to study the stress characteristics and damage mechanism of asphalt mixtures. The discrete element method can investigate the anisotropic heterogeneous materials and discontinuous dielectric materials from microscopic scale, which makes it an important way to research the mechanical properties and mechanism of asphalt mixture at the microscopic scale.The shear resistance of asphalt mixtures is an important index to evaluate the properties of asphalt pavements. Recently, a uniaxial penetration test, which was put forward by Professor Sun Lijun and Dr. Bi Yufeng at Tongji University, has become an effective mean to study the shear resistance of asphalt mixtures. Compared with the original tests studying the shear resistance such as the triaxial test, the uniaxial penetration shows advantages in similarity of pavement structure force with actual pavements, ability of damage mechanism reflection and asphalt mixtures properties evaluation. Meanwhile,the test process is simple and the test parameters are easy to be determined.In this paper,on the basis of CT technology and digital image processing technology,we study the shear resistance of asphalt mixtures using the discrete element method, then results of simulations are verified by the indoor uniaxial penetration test. The shear behaviors of different aggregate gradations, temperature, asphalt content, loading velocity on shear resistance and shear resistance of double-specimens with different aggregate gradations was studied. In the procession of simulating preparation, coordinates information of aggregate particles of asphalt mixtures SGC specimens was obtained by CT technology, then these specimens would be tested the shear resistance. Contact models were chosen according to the testing conditions, parameters of which was transferred from the macro parameters obtained from the corresponding mastics experiments. Then the uniaxial penetration tests were simulated and analyzed with the help of PFC3D. Combined with the experiment data, effects of different effective indexes,microstructure characteristics on the shear resistance were explored.The research results reveal that the shear resistance of asphalt mixtures is influenced by the aggregate gradation, temperature, asphalt content and the loading velocity; based on the CT technology and digital image processing technology, the uniaxial penetration of asphalt mixtures was well simulated using the 3D discrete element to evaluate the property of shear resistance.