Dynamic response of a flexible reinforced ecological bank protection subjected to impact loads

To clarify the impact resistance of flexible reinforced ecological bank protections with drainage blind pipe facings, model tests were conducted under simulated vessel impacts. The results showed that the drainage blind pipes provided cushioning and energy absorption, confining the deformation to within 0.88 m of the impact point. As the impact point height increased, the peak horizontal impact earth pressure increased by about 3%; meanwhile, the peak values of internal acceleration, top vertical deformation, and reinforcement deformation increased by about 10% to 15%, which increased structural failure risk. When the shock-absorbing pad thickness increased from 0.00 m to 0.08 m, internal acceleration, horizontal impact earth pressure, overall deformation, soil displacement, and reinforcement deformation were all reduced by 50% to 60%. Furthermore, the Hertz impact equation, modified with distribution coefficients, provided conservative estimates (1.1 to 3.3 times measured values) and captured damping effects within 13% error, whereas the ultimate bearing capacity method underestimated by 65% and neglected damping. Therefore, the Hertz impact equation with energy modification exhibits broader applicability, and their applicable conditions are given. This study examines the dynamic behavior of vertical flexible ecological bank protections and presents corresponding calculation methods, as a reference for future research.