Translational Inertial Effects and Scaling Considerations for Coarse Granular Flows Impacting Landslide-Resisting Barriers

Coarse grains accumulate at granular flow fronts and must be considered when studying granular flows impacting barriers. Experimental studies often use instrumented barriers comprising a load transducer and load-bearing plate. However, it is not clear how to scale the mass of these composite barriers relative to coarse grains such that forces induced are properly captured by the load transducer. This study considers the impact force from grains on instrumented barriers using both a physical flume and a discrete element method (DEM) model. Results reveal two main scaling considerations for granular flows impacting load-measuring systems: (1) the design of the load-measuring system, and (2) the model size. Considerations relating to the design of the load-measuring system include (1) the relative mass of the grains and the load-measuring system; (2) the spring element stiffness of the load-measuring system; and (3) the grain impact velocity. These are captured using a newly proposed dimensionless number. Additionally, discrete impacts appear to reduce in importance as the sizes of the flow and channel are increased, relative to the final static load due to the flow piling up, within the framework of Hertzian impact mechanics. This implies that small-scale DEM simulations adopting low elastic moduli (reducing discrete impact loads) may unintentionally correctly represent larger-scale impact dynamics.