Torrent Barrier Under Climatic Extreme Load Events – Forensic Analysis of the Fracture and Failure Processes

Abstract

Following heavy precipitation in the catchment area of the Pinnisbach torrent in Austria in 2015, a torrent barrier was significantly damaged due to extraordinary water levels and intense bedload transport. The bedload transport triggered by the barrier breach was partly captured in the downstream retention basin and partially diverted into the cone channel. To address this failure, the reverse engineering approach was applied. A failure analysis was performed to better understand the displacement process and quantify the overall load on the barrier structure. A detailed reconstruction of the failure mechanism employing advanced techniques like on-site inspections, numerical methods, and specific monitoring of the region area was conducted. The analysis revealed that the load initially assumed during the design and construction phase of the barrier was underestimated by 40% in certain areas, mainly due to an underestimation of water and debris load. Consequently, a more precise estimation of the applied load and considerations for the most severe scenario combinations are essential for ensuring structural safety. A rigorous analysis and assessment of this type of failure contribute to better implementing the findings into future risk mitigation strategies for similar structures and scenarios.