Finite element analysis for rockfall and debris flow mitigation works

Landslide risks arising from boulder falls and debris flows are commonly mitigated using rigid and flexible barriers. Debris–barrier interaction is a complicated process, so current design methods rely on the use of the pseudo-static force approach. In addition to physical testing, numerical simulations can be used to provide insight into the impact mechanism. This paper presents the applications of numerical models to simulate rigid and flexible barriers subjected to rockfall and debris-flow impacts, respectively. For rigid barriers, rock-filled gabions, a recycled glass cullet, cellular glass aggregates, and ethylene-vinyl acetate (EVA) foam were assessed for their performance as cushioning materials. From the results, empirical equations were established for predicting the boulder impact forces and penetration into the cushion layer. Amongst the materials considered in this study, rock-filled gabions appear to be the most promising for use in practice. For flexible barriers, finite-element models, calibrated using documented case histories, were developed to simulate the debris–barrier interaction. The models were used to investigate the barriers’ behavior under debris impacts from both force and energy perspectives. From the results, the hydrodynamic pressure coefficient was found to be lower than the current recommended value whilst only a small amount of debris energy was transferred to the barrier.