Shear Behaviors of Confined Flow: Insights for Understanding the Influences of Fractal Particle Size Distribution on High Mobility of Granular Flows

Abstract

Abstract Granular flows, such as rockslide debris flows, can reach high velocities and travel vast distances, but mechanisms behind this high mobility remain elusive. Using the Discrete Element Method, we implement confined shear flow with fractal particle size distribution to study the physical mechanisms inside the highly localized basal zones. Our results show that the shear strength of confined flow decreases at large fractal dimensions, and a notable transition in shear behavior also occurs with increasing fractal dimension: large particles exhibit low granular temperature and act as solid phase within a semi‐diluted suspension, and small particles enter the rolling regime. The small particles behave as interstitial fluids and reduce the shear strength of confined flow. We suggest that the reduction of shear strength stemming from the fractal particle size distribution may provide insights into the mechanisms within the highly localized basal zones, ultimately contributing to the high mobility of granular flows.

Keywords

• particle size distribution
• fractal dimension
• granular flows
• high mobility