Numerical Simulation For Compacting Characteristic Of Earth-rock Mixture With 3D DEM

Earth-rock mixture, resulted from mountain excavation or blasting, is composed of coarse and fine particles and widely used in highway embankment in mountainous area. Because of large gradation variation and uneven stone content, laboratory test can be much cost, and also, the influence of meso-structure parameter on the compaction quality can not be studied, and the basis for earth-rock mixture compaction mechanism analysis can not be provided. Compared with FEM, DEM has obvious advantage on the large deformation simulation, especially is suitable for the study of vibration compaction characteristics on earth-rock mixture. Compared with FEM, Characterize by simulating large deformation and displacement, DEM methods is suitable for the research of granular matter, such as the DEM simulation on earth and rock mixture compactor surface vibration experiment.Based on DEM, the vibration compaction test on earth-rock mixture is simulated, and the influence of meso and macroscopic parameters on compaction quality is studied. During the 3D DEM model foundation, the average value of grain composition is taken as representative value, to ensure the gradation requirements. The initial sample for test is generated through radius expansion, which is not only improves the establishment speed of the initial sample, but also contributes to ensure the random distribution of rough and fine particles. To solve the particle escape problem, during the model foundation, the velocity of all particles are set to zero after the radius expansion.In the simulation test, it is assumed that the density of coarse and fine particles are equal, and the effect of water is ignored, Then it is proposed that the porosity is suitable for the evaluation of earth-rock mixture DEM model compaction effect. On the basis, the effect of meso and macroscopic parameters on compaction quality is analyzed, and the simulation results are interpreted from vibratory compaction theory. The main conclusions obtained from the research are as follows: 1) The porosity decreases with the increase of the maximum particle size and the amount of stone, which is in accord with the laboratory test result. 2) The porosity decreases with the increase of the diameter ratio of test tube and maximum particle. 3) The porosity increases with the increase of vibration load frequency. 4) With the increase of the wall stiffness, porosity first increases and then decreases. 5) The porosity increases with the increase of the damping factor and particle stiffness, while the friction coefficient has little influence on porosity. The study results contribute to the analysis of earth-rock mixture compaction mechanism and the optimization of indoor and outdoor testing program and construction quality control.