Flume investigation of cylindrical baffles on landslide debris energy dissipation

Debris flows moving at high speed along valleys can bring disastrous consequences to downstream regions. Structural countermeasures are commonly installed along anticipated flow paths of debris flow risk areas in order to reduce debris flow mobility. The installation of cylindrical baffles, which are an open-type countermeasure, has increased because of their low construction cost, ability to filter rocks, and increased hydraulic continuity. Also, cylindrical baffles have advantages over rectangular baffles in that they have low drag force and effective energy dissipation caused by a higher interference of flows between baffles. However, comprehensive design guidelines for the specifications and arrangement of cylindrical baffles are lacking. Baffle design and installation to date have been mainly based on empirical approaches by engineers, as the influence of baffle array on debris mobility is not well understood. For the purpose of investigating the array effect of cylindrical baffles on flow energy dissipation, a series of small-scale flow tests was performed with installed baffles having varying heights and number of rows. High-speed cameras and a digital camera were installed at the top and the side of an experimental flume to capture flow behavior as simulated flows interacted with the baffles. Laser level sensors were also installed at the top of the flume to measure flow depth. After each test, the energy dissipation characteristics according to the height and number of rows of the baffles were analyzed. The analysis results showed that the use of baffles significantly decreased the downstream flow velocity and flow depth by 37% and 46% on average, respectively. Moreover, increasing the baffle height and the baffle number further enhanced the effect of baffles on the flow dynamics.

Automated summary

Debris flows moving at high speed along valleys can have disastrous consequences. The installation of cylindrical baffles along the flow path is a common countermeasure to reduce debris flow mobility. This study investigates the array effect of cylindrical baffles on flow energy dissipation through small-scale flow tests. The results show that the use of baffles significantly decreases flow velocity and depth, and increasing baffle height and number enhances their effectiveness.