Experimental study on tsunami wave forces on round-ended piers

To study the mechanism of tsunami wave forces on round-ended piers and the force calculation method, a series of round-ended piers with different ratios of length to width (L/D, D is the diameter of the semicircle at both ends, L is the rectangular length between two end semicircles) are taken as the research object of this study. Firstly, a series of tsunami waves are experimentally generated over dry-bed and wet-beds with different water depths in a dam-break flume. Secondly, the pressure time histories on the outer sides of the round-ended piers are presented and explored. After that, the characteristics of the resultant force and moment at the pier bottom, the maximum force and moment as well as the force and moment in the quasi-steady stage, are obtained and analyzed successively, to explore the influence of L/D. Furthermore, the influences of L/D to the mechanism of tsunami wave forces on round-ended piers are exhaustively investigated. The study indicates that, with the increase of L/D, almost unaffected pressure time histories on front side, obvious time delay in the impulsive stage and a slight increase in amplitude in the quasi-steady stage on the back side, are observed, accordingly L/D has a significant influence on the generated force and moment on round-ended piers. Finally, the calculation method of the maximum tsunami wave forces on round-ended piers and the corresponding coefficients are provided. This study can contribute to the safety design of round-ended piers in tsunami-prone areas.