Assessment of dynamic responses and impact resistance of corrugated plate-reinforced concrete tunnels under irregular rockfall scenarios

This article presents a composite tunnel rockfall protection structure (CPRC) employing galvanized corrugated steel plates as the inner formwork for reinforced concrete structures. It addresses the threats posed by frequent rockfall disasters in mountainous regions with complex geology. The research investigates impact damage from various rockfall shapes through numerical simulations and experiments on five representative forms, comparing traditional reinforced concrete structures RC with CPRC. The study highlights both structures' dynamic responses and damage characteristics across different impact scenarios, introducing the Residual Resistance Index RRI as a measure of post-impact safety performance. Results show that the numerical simulations align with laboratory tests, with discrepancies within 10%, validating the simulation method's accuracy in predicting impact resistance. Following impacts, both structures primarily displayed brittle concrete damage; however, the CPRC structure demonstrated a 79.46% reduction in concrete damage and an 86.31% decrease in reinforcement damage. The energy-dissipating properties of the corrugated plates significantly lowered rockfall penetration depth and impact energy transfer ratio, with an RRI exceeding 0.88 post-event. Additionally, the study reveals varying damage effects from different rockfall shapes, further supporting the CPRC structure's superior impact resistance and its effectiveness in preventing secondary disasters in tunnel engineering within mountainous terrains.