Forces on Vertical Wall Caused by Incident Bores

Abstract

The forces on a vertical wall due to the impact of a bore generated by a broken solitary wave were measured in the laboratory. The incident bores varied in height from 2.4 cm to 4.9 cm and in celerity from 75 cm/s to 126 cm/s. High‐speed motion pictures of the bore impact process were taken simultaneously with force measurements. The water particle velocities on the surface of the bore were obtained from the motion pictures using small floats. The maximum rise of the water surface on the wall exceeded twice the velocity head, based on the bore celerity for all conditions. The maximum measured force occurred after the maximum run‐up for all conditions of this study. The vertical accelerations in the run‐up jet at the wall explain some of the characteristics of the force record that have not been well understood. The maximum measured forces varied from five to nearly seven times the hydrostatic force, based on the height of the incident bore and the local still‐water depth. For the four largest bores, the theory of Cross (1967) was in reasonable agreement with the maximum measured force.