Horizontal loading experiments on reinforced gravity type breakwater with steel walls

Abstract

In the 2011 off the Pacific coast of Tohoku Earthquake, especially coastal areas of the Pacific Ocean suffered extensive damage by tsunami. Then, there were needs to develop reinforcement methods for existing breakwaters against tsunami force. The authors proposed a method to reinforce a breakwater against tsunami with a steel wall behind the breakwater. This report presents the experimental results of the breakwater reinforcing method. In the proposed method, steel piles are inserted behind the breakwater and rubbles are filled between the caisson and the piles. The model caisson failed in sliding mode without this improvement method. When it was reinforced with steel walls and filling, the horizontal resistance of the model caisson improved effectively. The failure mode of the caisson changed from sliding mode to ground failure mode. By analyzing the bending moment of the steel wall, the stress distribution in the wall from the caisson via filling and the ground was obtained and failure surface of the ground can be estimated.

An Overview on Development of Countermeasures for Breakwater against Earthquake and Tsunami Induced Damage

“…Recently, some efforts have been made to develop countermeasures for foundation of breakwater in order to make it resilient against damage caused by compound disaster triggered by earthquake and tsunami. Kikuchi et al [12] suggested a reinforced foundation using steel walls into foundation ground behind caisson. They developed the reinforced foundation to mitigate tsunami induced damage of breakwater.…”

Model experiment and numerical analysis of horizontal subgrade reactions acting on flexible walls

“…To improve the tsunami resistance of existing caisson-type composite breakwaters, a structure in which steel pipe piles are continuously driven behind the caisson and filled with soil between the caisson has been proposed [1,2]. Figure 1 shows a schematic of this structure.…”