Numerical investigation of effects of “baffles - deceleration strip” hybrid system on rock avalanches

• Published in: Journal of mountain science 2019-02, Vol.16 (2), p.414-427
• Main Authors: Bi, Yu-zhang, He, Si-ming, Du, Yan-jun, Shan, Jie, Yan, Shuai-xing, Wang, Dong-po, Sun, Xin-po
• Format: Article
• Language: English
• Subjects: Avalanches; Baffles; Deceleration; Design optimization; Discrete element method; Dissipation factor; Distance; Earth and Environmental Science; Earth Sciences; Ecology; Energy dissipation; Energy exchange; Environment; Geography; Hybrid systems; Impact loads; Kinetic energy; Landslides; Mountain regions; Mountainous areas; Protection; Rocks; Segregation; Strip
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-018-4908-3

Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles - deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discrete element method (DEM). The effect of the optimization of hybrid protection system (nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure (L m ) is also a key factor. The shorter the distance L m (30m) is, the higher the maximum impact force are. The longer the distance L m (70m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing its angle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches: (i) block the fine particles directly; (ii) form the particles bridge between nails and baffles; (iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system.