Abstract
Many coastal protection facilities were damaged by the 2011 Off the Pacific Coast of Tohoku Earthquake and the subsequent tsunami, which spread inundation to the coastal plain area. Countermeasures of compound disaster by future mega earthquake such us, Nankai trough earthquake having high probability etc., are issues that should be resolved urgently. The resilient structures that can reduce damage when they are subjected to earthquake and tsunami higher than the design earthquake and tsunami are being developed. The authors developed a resilient reinforcement technique of breakwater foundation using gabion mound (mound covered with gabion) and steel sheet pile that can minimize damage when the tsunami is higher than the design tsunami height. In this research, model tests and elements tests were performed to evaluate the seismic resistant behavior of the proposed reinforcement technique. To that end, the authors performed triaxial tests for the rubble used as mound material in the model test to evaluate shear deformation properties during static and dynamic loading. The authors then performed shaking table model tests in 1G gravitational field to evaluate the effect of steel sheet pile installation and gabion reinforcement. Results of this research show that the mound material can mobilize excellent shear resistance under both static and seismic loading condition. Furthermore, the results also made it clear that the settlement and deformation of the breakwater during earthquake could be restricted by reinforcing the foundation using steel sheet piles and gabion.
