The mechanical characteristics of granular flow based on the chute experiment

Clastic rock avalanches are typically classified as granular flows and are characterized by complex dynamic behaviors. However, current understanding of these processes remains limited, hindering the development and implementation of effective hazard prevention and mitigation strategies. To comprehensively investigate the dynamic characteristics of granular flow, this study utilized rounded sand as the experimental material and conducted chute experiment by varying the inclination angle (θ) and the gate size (h_g). The results indicate that at various stages of a single granular flow event, the dimensionless velocity presents a linear relationship with flow thickness, consistent with previously established flow rules. For a constant gate size, both the tangential force (F_y) and normal force (F_z) decrease with growing slope during the stable thickness phase; At a fixed slope θ, the values of F_y and F_z diminish as the gate size drops. Additionally, the basal friction coefficient \mu _\mathrmb , which is defined as F_y/F_z, generally exhibits a descending trend as the flow thickness decreases during the stable thickness phase across different conditions. When the flow thickness is large, the velocity profiles tend to display a convex-concave distribution, providing empirical support for the non-local rheological behavior of granular flows. By re-scaling the dimensionless velocity using tan⁴(θ), all velocity distribution curves can be effectively collapsed onto a single convex-concave master curve. During a single granular flow event, the closer the particles are to the surface, the higher their kinetic temperature would be. The findings of this study can provide theoretical support for the prediction and prevention of geological disasters such as landslides, rock avalanches, and debris flows.