Numerical investigation of effects of “baffles - deceleration strip” hybrid system on rock avalanches
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 (Lm) is also a key factor. The shorter the distance Lm (30m) is, the higher the maximum impact force are. The longer the distance Lm (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.
Key wordsRock avalanches Baffles Hybrid system Energy dissipation Impact force
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The authors thank all anonymous reviewers for helpful suggestions. This work was supported by the Major Program of the National Natural Science Foundation of China (Grant No. 41790433; Grant No. 41772312; Grant No. 41472325), the NSFC-ICIMOD Collaborative Project (Grant No. 41661144041), Key Research and Development Projects of Sichuan Province (2017SZ0041), Scientific Research Foundation of Graduate School of Southeast University (YBJJ 1844), and Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX17_0130). A special acknowledgement should be expressed to Prof. SONG Dongri for his helpful discussions.