Abstract:In order to analyze the size effect in discrete material flow and reveal transient behaviors of the mass flows in engineering practice at different scales, the experiment systematically investigated the collapse and flow process of the cohesionless granular columns driven by gravity using the particle high-speed measurement device and a constructed quasi-2D particle collapse experimental platform. The influences of column aspect ratio, as well as initial system size on the mobility and deposit morphology of the collapsing material were mainly analyzed by the particle image velocimetry(PIV)technique. The results showed that the flow front position of the granular columns with different initial lengths exhibited similar evolving characteristics with time, but the size change of the system had a significant effect on its final deposit morphology, especially the flow distance. By analyzing the critical length at which the size effect disappears, a scaling law of flow distance of a granular column with its aspect ratios and initial length was proposed, which can be used to accurately characterize the effect of column size on the mobility of collapsing material.