Clogging mechanism of pervious concrete: From experiments to CFD-DEM simulations

Abstract

The flow characteristics and clogging laws of micro particles with different sizes on ground surface passing through porous infiltrated materials were investigated. Experiments with surface runoff plugging on porous infiltrated materials were conducted and analyzed, combined with coupled computational fluid dynamics - discrete element method (CFD-DEM) simulations. In the study, the standard quartz sand particles of less than 0.3 mm, 0.3–0.6 mm, 0.6–0.9 mm and 0.9–2.2 mm were selected for the permeable material clogging experiment. The CFD-DEM coupling model was verified by comparing it with the recorded permeability coefficient from the experiment. The seepage velocity, total force of the fluid and spatial distribution of particle with different sizes were analyzed in detail by the model, and the influence of the change of the particle position at different time on the blockage of permeable material was determined. The results of experiments and numerical simulations indicate that in the initial stage of seepage, the rapid formation of clogging of the particles in the surface layer leads to an evident decrease in the permeability coefficient. Due to the small pore structures of the porous permeable material, the particle with sizes from 0.6 to 2.2 mm are blocked within 2 cm of the surface layer, resulting in obstructing 0.3–0.6 mm particles in the wake. However, particles less than 0.3 mm can penetrate deep into the permeable material, and accumulate in the deep pores, eventually forming a deep blockage with evolution of time. The above results are also normalized with characteristic scales, and self-similarity existed in the clogging phenomenon are discovered. The whole research realizes the unification of experiment, numerical simulation, and dimensionless analysis, and it is believed that the obtained laws can provide guidance for further relevant studies on the plugging of pervious materials.