JP2579402B

PURPOSE:To enhance the water affinity at a water front and to have a breakwater function by blowing up sea water with the use of an air-piston type. CONSTITUTION:A cave 16 is formed on the rear side of a wave receiving surface 12 of a caisson 10, and several through-holes 18 communicated with the cave 16 are formed in the water receiving surface 12. A tapered part 16a by which the cross-sectional area of the cave 16 is gradually decreased toward the top surface 14 is formed in the upper part of the cave 16. Further, the tapered part 16a is communicated with a spouting passage 20 opened at the top surface 14. The wave receiving surface 12, the rear surface 16b of the cave 16 and the spouting passage 20 are inclined at an obtuse angle theta with respect to the horizontal surface. Further, a mound 60 is formed so that the depth of water is gradually decreased toward the caisson 10 is formed offshore from the caisson 10. Waves are broken before it reaches the caisson 10, and the energy of waves may be efficiently used for blowing up sea water.