An Equivalent Stiffness Flexible Barrier for Protection Against Boulders Transported by Debris Flow

Flexible ring nets exhibit complex nonlinear mechanical behaviour when subjected to static and dynamic impact loads. This research presents the development of an efficient numerical model for assessing the performance of flexible netting barriers used in debris flow and rockfall risk mitigation. The model is calibrated through benchmark analyses and based on the equivalent stiffness method. The results demonstrate that the proposed numerical approach offers a significant computational cost reduction of 80% compared to complex numerical models while maintaining high accuracy. The coupled Eulerian–Lagrangian finite element method (CEL) is employed to simulate fluid–debris–structure interaction, showing damage characteristics consistent with flexible ring net barriers. The model is suitable for accurately determining the impact forces acting on the barrier and presents the debris behaviour and movement at various flow velocities. Notably, the results confirm that the presented model is capable of evaluating the interaction between the flexible barrier and debris flow with boulders and is an efficient approach to estimating the performance of flexible protection subjected to impacts.