Numerical simulation of responses of flexible rockfall barriers under impact loading at different positions

Flexible rockfall barriers have been widely used to mitigate rockfalls and protect residential buildings, railroads and highways from such natural hazard. Evaluation of the performance of flexible rockfall barriers are conventionally conducted using the full-scale impact tests in accordance with European guideline ETAG 027, in which the impact position is specified at the centre of the middle functional module. However, the trajectory of a rockfall in real case is random such that the impact position is unknown. The influence of different impact locations has not been reported in literature. In this paper, a full-scale test on a typical flexible barrier system is carried out and then used to calibrate an advanced three-dimensional finite element model, which is proposed for parametric study for the investigation of dynamic response of a typical flexible rockfall barrier under impacts at different positions. The numerical results show that the impact location will influence the residual height and maximum elongation of the flexible barrier. Although the impact position slightly affects the peak forces of support ropes, it will significantly influence the peak forces of the upslope anchor ropes and lead to unsafe anchor design. The proposed model can accurately predict the behaviour of flexible barriers and help designers to consider more practical conditions which are not specified in ETAG 027.