Abstract: The baffle, as a kind of mountain disaster protection structure, can effectively dissipate the movement energy of rock avalanches and restrain the movement distance and speed of rock avalanches. The construction of a baffle’s speed bumps between the rock avalanches gully and the disaster zone can greatly protect the disaster zone. In this study, based on the physical model experiment, the dynamic impact response of the channelled rock avalanches is implemented on the arc-shaped, square and cylindrical baffles. The effects of three types of baffles on the motion performance of channelled rock avalanches are discussed, and the structural optimisation of the arc-shaped baffles is further investigated. The results show that the baffles can effectively reduce the channelled rock avalanches accumulation distance and control the movement speed. Among the baffles of these three shapes, the blocking effect of the arc-shaped baffles and the square baffles is more efficient than that of the cylindrical baffles. Owing to the concave shape of the arc-shaped baffles, the blocking effect is much better than that of square baffles on the deposit areas and deposit depth. At the same height and diameter, the arc-shaped baffle volume has 22.6% and 39.2% less than the cylindrical baffle and the square baffle, respectively. Thus, the production cost of the arc-shaped baffle is lower than another two baffles. When the row of the arc-shaped baffles is increased from one to three, its blocking rate is increased from 7.2% to 4.5% as well. An appropriate increase in Ld can improve the energy dissipation efficiency of the arc-shaped baffles. This can provide theoretical and technical support for the application of pile groups in channelled rock avalanches control engineering.

Key words: channelled rock avalanches, baffles system, arc-shaped baffles, optimal layout, blocking effect