Technologies and Solutions

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.

Tsunami/Storm Surge Disaster Mitigation Structure: T-ORCA

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).

Features

  • 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.