Design of a Barrel-Vault Cofferdam

A unique proposal for the construction of a cofferdam for repair work on the walls of a canal consists of a ring-reinforced steel barrel-vault with rubber bearing pads and seals at the edges and end. The general instability of the skin-ring combination commonly is checked by comparing the line load equivalent to a tributary length times the pressure with the ring-buckling line load. The ring in this case has its ends free to slide and in addition may be affected by eccentricity at the ends, by initial movement or elastic support of the ends or by out-of-roundness. These and other effects are analyzed and discussed with the problems of design of such a cofferdam in view.