Towards realistic simulations of the impact dynamics of boulders on rock-filled gabion: Combined effects of rock shapes and their crushing strength

Rock-filled gabions are used to shield barriers and galleries from boulder fall in mountainous regions. A challenge in the design of rock-filled gabions lies in the estimation of the impact and transmitted loads. Furthermore, the effects of irregular rock shapes and rock crushing during the impact process compound the difficulty in estimating the design loads. In this study, a discrete element method model was used to conduct a parametric study to investigate the combined effects rock shape (bulky and flaky) and crushing strength (20 to 50 MPa) on the dynamic response of rock-filled gabions subjected to an impact energy of 70 kJ from a boulder. Results show that rounder rocks should be used to attenuate concentrated impact loading for rocks with a high crushing strength (50 MPa in this study). The maximum impact and transmitted loads on flaky rocks are about 20% larger compared to bulky rocks. The angularity of flaky rocks form force chains that restrict rotation so that they can sustain high loads. In contrast, angular rocks should be used for rocks with low crushing strength (20 MPa in this study). The maximum boulder impact and transmitted loads, respectively, for flaky rocks are about 20% and 33% less than those for bulky rocks. Flaky rocks help to reduce transmitted loads and distribute loading more uniformly. A 30% increase in cushion thickness is recommended to ensure robust cushioning performance for flaky rocks with a crushing strength of 20 MPa.

Automated summary

The study shows that different shapes and strengths of rocks have different effects on the dynamic response of rock-filled gabions. Round rocks are suitable for high-strength rocks to attenuate impact loads, while angular flaky rocks are suitable for low-strength rocks to reduce transmitted loads and achieve uniform distribution.