Quantitative analysis of debris-flow flexible barrier capacity from momentum and energy perspectives

In-depth understanding of debris-structure interaction is hindered by a lack of physical data of debris flow impacting structures. This study reports a set of centrifuge experiments investigating the impact load exerted by debris flow on rigid and flexible barriers. A combination of high-speed imagery and load-displacement sensors enabled a comprehensive grasp of the impact details, including flow depth, velocity, impact pressure, bending moment, and cable force-elongation of flexible barrier. Test results reveal that the debris-structure interaction plays a major role in the energy dissipation and impact load reconstruction. The built-up of static load behind the barrier occurs simultaneously with the grow-up of impact force. As a result, the momentum flux of incoming flow is not merely a surrogate of the impact force. A quantitative analysis from the energy perspective has been conducted. Under the experimental conditions of this study, debris flow impact results in over 90% of debris energy dissipated through the internal and boundary shearing, leaving < 10% absorbed by the flexible barrier. Findings from the energy and momentum perspectives could facilitate the optimization of flexible barriers in mitigation of debris flow hazards.