Three-dimensional discrete element model for tri-axial tests of graded stones under different gradations

Abstract

In Highway Engineering, graded stones are popularly used in constructing base or subbase layers of pavements. Under cyclic vehicular loads, deformation and strength of graded stones are impacted by various factors. Those factors may include loading magnitudes, aggregate gradations, and particle morphological features. Laboratory tests are used as conversational approaches to predict and characterize performance of the designed graded stones. However, conversational tests are expensive and less efficient. As an alternative approach, a virtual testing method based on the discrete element method (DEM) is lab-independent with the higher efficiency. Additionally, micro-scale or meso-scale features of mixtures may be investigated through virtual tests. Under this background, objectives of this research are to present a three-dimensional discrete element modeling approach for virtual tri-axial tests of graded stones and to improve the fundamental understandings of graded stones’ mechanical behaviors through analyzing the virtual testing results. In the three-dimensional DEM model, aggregate particles are simulated by the spheres in different diameters and given granular parameters to simulate realistic conditions. The cylindrical samples with diameter of 20 cm and height of 40 cm are prepared in this research and the virtual tests are performed with different gradations. Mechanical performance of stress and strain is recorded during the simulation for further analysis. Through this virtual test, the effect of gradation on mechanical properties of coarse aggregate has been presented.