An experimental investigation of the interaction between near-critical debris flows and flexible barriers: Focus on successive surges and cable failure

This paper deals with the interaction of near-critical debris flows with a flexible barrier, focusing on the frequent situation where the debris flows occur as a succession of surges and on the consequences of partial barrier failure. Flume experiments in similitude with real-scale were performed with debris flows consisting of a high solid fraction and water-saturated mixture of clay, sand and large angular particles. Flume inclination, number of surges and mass of mixture released per surge were varied between tests. The influence of all these parameters on the kinematics and deposition of the debris flows and on barrier loading were investigated. The load measured at the barrier was lower in the case of multiple surges than in the case of a single surge of the same cumulated mass. In addition, subsequent surges have a limited influence on loading of the barrier cables at rest, and deposits tend to accumulate further away from the barrier when a high mass of material is already deposited. Finally, the description of cases of failure indicates that some, but not all, partial barrier failures result in limited debris release. • Large experimental data set in relation to succession of surges impacting a flexible barrier. • Near-critical flows of a large solid fraction and coarse mixture. • Main factors with influence on the deposit shape and barrier loading are highlighted. • Successive surges revealed less detrimental to the barrier than single surge of same total mass. • Various barrier failure types are identified.