Optimization strategy for flexible barrier structures: Investigation and back analysis of a rockfall disaster case in southwestern China

Abstract. Field investigations and back analyses were conducted on a rockfall hazard. The flexible barrier protection system constructed along the roadside got damaged by the rockfall impact and lost its ability to mitigate. Vital physical characteristics like rockfall trajectory and kinetic energy were presumed based on the data from an aerial survey and the slope digital model. A numerical model, including slope, rockfalls, and flexible barrier, was created, so the impacting process was reproduced. It demonstrates that the rockfall’s impact kinetic energy is only around 40 % of its design protection energy. The improper connections of members are the leading causes of damage, which prevent the flexible barrier from producing significant deformation and reduce its capacity to absorb impact force. The damage can be avoided by changing the members’ connections to improve the nets’ and ropes’ ability to slide and deform. The calculation results indicate that the optimized model’s performance in terms of complete protection is three times better than the actual project’s. The findings can be used as a guide when designing a flexible protection system that performs better.