Capture of near-critical debris flows by flexible barriers: an experimental investigation

Abstract. This study addresses the key issue of the interaction between debris flows and flexible barriers based on small-scale experiments for which both the flowing mixture and the barrier were designed to achieve similitude with real situations in Alpine environments. The considered debris consisted of a large solid fraction mixture with large and angular particles, flowing down a moderately inclined flume and resulting in near-critical flows, with a Froude number in the 0.9–2 range. The flexible barrier model consisted in 3D printed cables and net. The flow characteristics, evolution and deposition after contact with the barrier as well as the deformation and the loading experienced by the barrier were addressed varying the flume inclination and released mass. Four different interaction modes between the flow and the barrier are identified increasing the flow kinematics. A model based on the hydrostatic pressure assumption reveals relevant for estimating the total force exerted on the barrier when all the released material is trapped. This force doubles in case there is barrier overflow.