A STUDY ON COUNTERMEASURE AGAINST SCOUR BEHIND COASTAL DIKE DUE TO TSUNAMI OVERFLOW

Abstract

 The 2011 Tohoku Tsunami severely damaged the Tohoku areas. Failures of seawall, mainly due to scour on the land side, appeared to increase the inland tsunami damage. Recently, the local scour is successfully simulated based on ISPH (Incompressible Smoothed Particle Hydrodunamics) model, while it does not include the deposition process in the model. In this study, the deposition proess was introduced to the ISPH method to improve the model appicability. By using this new model, a countermeasure for tsunami overflow is proposed for the condition where the land side area is so limited that the land fill is not able to be introduced behind the seawall. It is suggested that sill structure behind dyke is able to reduce the scour around the land side of the seawall as well as the momentum of tsunami flow.