Analysis of the load exerted by debris flows on filter barriers : comparison between numerical results and field measurements

The hazard posed by debris flows onto mountainous settlements often requires structural countermeasures, such as barriers, to be installed. There is a worldwide trend in employing barriers that are partially impervious to the flow, trapping the coarsest sediment, and reducing the erosive power of the flow early on. However, many design choices with respect to effectiveness and structural integrity are not trivial, because there is a poor knowledge of the flow-structure interaction mechanism. In this work, we report results from a monitoring campaign on a barrier installed within an experimental site. At the site, the structural response of the barrier is recorded any time an event occurs. However, the results exhibit features that do not fully reconcile with the load model prescribed by the available guidelines. To gather insight, we propose a numerical study based on the use of the Discrete Elements Method for the flow simulation and the Finite Element Method for the structural response of the barrier. The compatibility between site measurements and numerical output validates the use of the DEM-FEM model. It also highlights certain key details on the load pattern on the barrier that are not yet included in existing guidelines.