Jun Mitsui, Masato Yamamoto, Satoshi Noboru, Ichiro Nishiwaki


Breakage of wave dissipating concrete blocks occasionally occurs due to collision with other blocks during rocking motion under wave action. Therefore, an understanding of the impact forces induced by rocking blocks is important to solve this problem. The authors formulated impact forces using impact velocity, properties of materials, and dimensionless parameters depending on the shape of blocks to propose a theory to predict the magnitude of impact force. Fundamental drop tests using tetrapods were also conducted to confirm the proposed formula. Various sizes of blocks were used in the drop tests to reveal the scale effects. It is shown that predicted impact forces agree well with measured ones and that no scale effects concerning impact force seem to exist in the range of this study.


wave dissipating concrete block; impact force; drop test


Burcharth, H.F. 1981. Full-scale dynamic testing of dolosse to destruction, Coastal Engineering, 4, 229-251.

d'Angremond, K., J.W. van der Meer, and C.P. van Nes. 1994. Stresses in tetrapod armour units induced by wave action, Proceedings of 24th International Conference on Coastal Engineering, ASCE, 1713-1726.

Nishigori, W., T. Endo, and A. Shimada. 1986. On stress in Tetrapods under wave action, Proceedings of 20th International Conference on Coastal Engineering, ASCE, 2119-2132.

Terao, T., K. Terauchi, S. Uchida, N. Shiraishi, K. Kobayashi, and H. Gahara. 1982. Prototype testing of Dolosse to destruction, Proceedings of 18th International Conference on Coastal Engineering, ASCE, 2062-2078.

van der Meer, J.W., and G. Heydra. 1991. Rocking armour units: Number, location and impact velocity, Coastal Engineering, 15, 21-39.

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