A case study on the closed‐type barrier effect on debris flows at mt. Woomyeon, korea in 2011 via a numerical approach

Abstract

Debris flows are capable of flowing with high velocities and causing significant economic and infrastructural damage. As a hazard mitigation measure, physical barriers are frequently installed to dissipate the energy of debris flows. However, there is a lack of understanding on how barriers affect and interact with debris‐flow behavior (e.g., velocity and volume). This study inves-tigated the changes in debris‐flow characteristics depending on the installation location of barriers. Mt. Woomyeon, which is located in Seoul, Korea, was the site of a major debris‐flow event in 2011. This study modeled this event using DAN3D, numerical software based on smoothed particle hydrodynamics (SPH). Our numerical approach assessed changes in debris‐flow behavior, including velocity and volume, as the debris flow interacts with four closed‐type barriers installed at separate points along the flow path. We used DAN3D to model the barriers via terrain elevation modifica-tions. The presence of a closed‐type barrier results in the reduction in the debris‐flow velocity and volume compared to when no barrier is present. Most notably, the closer a barrier is installed to the debris source, the greater the velocity decrease. By contrast, a barrier that is constructed further downstream allows the debris flow to undergo entrainment‐driven growth before confronting the barrier, resulting in a larger debris deposition volume that can often cause overflow, as shown at our particular study site. The presented results highlight the effectiveness of barriers as a method of hazard mitigation by providing insight into how such installations can alter debris‐flow behavior. In addition, the findings can provide a reference for future debris‐flow barrier designs, increasing the effectiveness and efficiency of such barrier systems.