Application of flat-joint contact model for uniaxial compression simulation of large stone porous asphalt Mixes

Abstract

Discrete element method has been widely used to simulate performance indicators of asphalt mixture, but the contact model of particles is still the most key step in the simulation. The Flat-Joint Contact (FJC) model is a new theory to describe the contact conditions among the particles in granular materials, which is a new proposed model for geotechnical materials numerical simulation and has been integrated in the Particle Flow Code (PFC) recently. The applicability of the FJC model in Large Stone Porous asphalt Mixes (LSPM) is investigated in this paper. This paper rebuilds the irregular particles of field coring specimens using the image processing technology. Then, a three-dimensional discrete element program is developed to simulate the uniaxial compression test of LSPM with different aggregate gradations. The compressive strength, coordination number, contact point, and energy of LSPM are analyzed to characterize the performance in the testing process, and the simulation is compared with the laboratory testing to verify the reliability. Results show that the average coordination number can be used to evaluate the compressive strength, the four-parameter Boltzmann distribution can be used to describe the cumulative distribution probability of contact points. Energy indicator can be estimated by macroscopic compressive strength and reflected the mechanical property. Compared with the parallel bonding contact model (PBC), the FJC model simulation is closer to the laboratory test. Therefore, the proposed programs and FJC model are suitable to simulate the uniaxial compression process of the LSPM.