Tsunami/Storm Surge Disaster Mitigation Structure: T-ORCA
Demonstrates a disaster mitigation effect by utilizing wave energy. Under ordinary conditions, T-ORCA is no different from a general box-type upright seawall, but during tsunami/storm surge, the force of the waves raises the crown to an erect position, thereby reducing the wave overtopping rate and amount of overflow.
Use in Combination with Repair and Reinforcement of Structures
By installing a wave chamber with a retractable crown at the front side of an existing upright seawall, it is possible to obtain a disaster mitigation effect without changing the reclamation normal line.
(*Depending on site conditions, it may be necessary to change the reclamation normal line).
- In comparison with box-type caisson seawalls with a fixed crown, the wave overtopping rate can be reduced to 1/3 or less (results of laboratory experiment).
- In comparison with box-type caisson seawalls with a fixed crown, the time until inundation of the hinterland can be delayed. (*Depending on site conditions, it may not be possible to prevent overflow completely.)
- Wave energy can be dissipated because air and water in the wave chamber generate turbulence efficiently when a retractable crown is adopted. The wind wave reflection coefficient is suppressed to the same levels as with upright wave-dissipating caisson seawalls.