Influence of Energy Dissipator Configuration and Impact Location on Energy Dissipation Distribution of Flexible Rockfall Protection Structures

Flexible passive protection structures are a sustainable and environmentally friendly solution for rockfall protection in mountainous regions, owing to their lightweight components and low environmental impact. Their energy dissipators absorb the impact kinetic energy of falling rocks through plastic deformation, accounting for 60~80% of the total energy dissipation. To clarify the influence of energy dissipator configuration and impact location on the energy dissipation distribution, an abstract two-stage model of ring nets and a three-stage equivalent model of braking ring groups were established, and an overall numerical model validated against a 1500 kJ full-scale impact test was constructed. Results show that, under the ETAG central impact mode, energy dissipators exhibit delayed activation and a high dissipation ratio, with the upper-to-lower ratio approaching unity. At a fixed impact energy level, the structural energy-dissipation ratio decreases with increasing working cable force (0.6~0.8 at 1000 kJ) and increases with impact energy level at a decreasing rate. When the impact location deviates from the center, the energy dissipation distribution changes markedly, reaching up to 1.8, 1.2 and 1.15 times the central values for the upper anchor rope, upper support rope and lower support rope. These findings support the sustainable design of flexible protection structures.