Advances in Design of Barriers for Debris Flow Impact

Debris flows, which often contain large boulders, may impact and destroy downstream facilities such as buildings and bridges. To protect human lives and infrastructures in mountainous regions from debris flows, engineering countermeasures such as barriers and dams are often installed along the predicted flow paths. The design of safe countermeasures relies on robust predictions of the impact force and provision of adequate retention capacity of the measures. However, impact forces are difficult to estimate because of limited field evidence associated with the prevailing impact mechanisms, diversity of flow types that may exist (e.g., stony and muddy debris flows), and the scale-dependent nature of debris flows. Consequently, the recommendations provided by design guidelines in different countries differ. In this chapter, we provide an overview of the existing design practices, including the commonly used impact models and assumed impact scenarios, and state-of-the-art research findings that enable the optimization of the design of engineering countermeasures against debris-flow impact. The practice of designing barriers against debris flows is still evolving as new research findings become available. Future research may focus on topics such as the dynamic interaction between debris flows and mitigation structures.