부산대학교 도서관

A numerical study was conducted on tsunami-induced hydrodynamic forces acting on armor blocks covering a rubble mound to validate the assumption in the derivation process of the Isbash formula, which is a method that calculates the required mass of an armor block. The results from the numerical experiment of the velocity and pressure distributions around the blocks agreed well with those from the hydraulic model experiment. The calculated results indicated that (1) the hydrodynamic force works on the plane of the armor block locally, resulting in the rotating collapse of the blocks; (2) the armor blocks around the shoulders both downstream and upstream receive large hydrodynamic forces and consequently be easily damaged; and (3) the hydrodynamic force can decrease (or increase) with increasing (or decreasing) sea levels even if a similar magnitude of cross-sectional average velocity is applied. This study indicates the rationality of using mechanical moment to evaluate the stability of armor blocks, along with the importance of considering the effects of the lift force as well as the drag force.