EFFECT OF FLEXURAL RIGIDITY OF PILES ON HORIZONTAL RESISTANCE OF REINFOCED GRAVITY TYPE BREAKEWATER WITH STEEL PIPE PILES

In The 2011 off the Pacific coast of Tohoku Earthquake, coastal area breakwaters of the Pacific Ocean were suffered extensive damage by tsunami attacks. A method for reinforcing an existing caisson type breakwater against tsunami attacks with a steel pipe piles behind the breakwater and filling rubbles between breakwater and piles were proposed. Horizontal loading experiments on model breakwaters were conducted on dry sand condition to develop a design verification method on steel piles used in this reinforcing method. Flexural rigidity of a pile and number of piles used in an experiment were changed. Resistance increment of the caisson was mostly affected by total flexural rigidity of piles in a unit length along breakwater length. The paper also discussed force acting on piles from the caisson side. Clarifying the distribution and intensity of the force acting on the pile can make an effective design verification method of piles to be used in this reinforcement.