Preliminary Investigation on Overall Permeability of Granular Mixed Materials

Many geomaterials are mixed composites and the permeability coefficient of each phase differs widely. Determining the overall permeability coefficient of mixed materials is still a challenging task due to the heterogeneity. Few studies have focused on the physical mechanism of the hydraulic property of mixed geomaterial. To address this lack of knowledge, a constant head permeability test and numerical simulation based on CFD (computational fluid dynamics)-DEM (discrete element method) are conducted to investigate seepage performance of mixture specimens. To explore the effects of content of each phase on the overall permeability coefficient, glass beads as inclusion phase are distributed uniformly and randomly in quartz sand, and different contents of inclusions ranging from 0% to 60% are considered. The experimental and numerical results show that the overall permeability coefficient increases with the content of the glass beads and porosity. It can be seen that the overall permeability coefficient is not only related to the content and property of each component, but also more determined by the interconnected paths. This work provides new sights for the future research of hydraulic property of mixed materials.