Sliding Displacement of a Freestanding Rigid Barrier Subjected to Multiple-Boulder Impact

Abstract Natural hazards such as rockfalls, rock avalanches, and debris flows pose serious threats to lives and property in the vicinity of hillslopes, necessitating protective structures to be erected around built-up areas and along transportation corridors to contain fallen debris. Research to date on the sliding of a freestanding rigid barrier has primarily focused on the scenario of a single, isolated impact by a fallen boulder. While previous studies have proposed closed-form expressions to predict this, their applicability to complex loading scenarios remains limited. In particular, existing relationships fail to capture the cumulative sliding displacement that occurs during rockfall or debris flow events involving multiple impacts from a large number of boulders. This study aims to extend deterministic models, originally developed for single-boulder impact, to predict the cumulative sliding displacement of barriers under more realistic multiple-impact scenarios, thereby addressing the existing knowledge gap. The developed analytical model gives an estimate of the amount of cumulative sliding in probabilistic terms for a given quantity of boulders, the average size of the boulders, and a common velocity of impact. The derivation of the model involved integrating deterministic and heuristic predictive relationships with observations from impact experiments and stochastic simulations.