Hydraulic Stability of Randomly-Placed Rakuna-IV for Rubble Mound Breakwaters in Case of Non-breaking and Non-overtopping Waves Using Physical Models

  • Nguyen Quang LuongEmail author
Conference paper


In recent years, very large concrete blocks have been used for many coastal protection works, especially rubble mound breakwaters in deep-water areas. These concrete blocks have been being modified and improved in order to be well adapted to different wave conditions and to meet the increasing and diverse demands of the construction of deep-water ports and coastal protection works. Along with the structural integrity, the hydraulic stability of concrete blocks has also been considered an important issue for rubble mound breakwaters. Recently, there have been various severe failures of many breakwaters covered by the complex form of slender concrete blocks without reinforcement, which caused by the breakage and failure of these blocks when the stresses exceed the strength or mechanical durability of the material, especially when the concrete blocks rock, rotate and collide under wave impacts – which is known as rocking mechanism. This is a common phenomenon in case of double-layer and randomly-placed slender concrete blocks for the protection of rubble mound breakwaters.

As a general development trend in the world, Rakuna-IV is a new type of Japanese concrete block, which was invented by Nikken Kogaku in 2007 and has been applied to many breakwaters and coastal protection works. So far, no research has been made on the hydraulic stability as well as the structural integrity of concrete blocks in case of random placement and non-breaking waves for rubble mound breakwaters. This is an urgent practical issue when in most cases, especially in deep water, the concrete blocks for breakwaters are usually placed randomly during construction. This paper focuses on some results of the study on hydraulic stability of Rakuna-IV blocks in case of non-overtopping, non-breaking waves and random placement, using physical models.


concrete armour unit CAU rubble mound breakwater Rakuna-IV hydraulic stability physical model 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. CEM-US, 2006. Coastal Engineering Manual, Report EM 1110-2-1100 Part VI, ASCE.Google Scholar
  2. Tuan, T. Q., Matsushita, H., Taki, Y. and Luong, N. Q. (2012): Stability of Newly-Improved Wave Dissipating Blocks for Rubble Mound Breakwater. In Proc. of 4th ICEC, pp.361-369.Google Scholar
  3. Tuan, T.Q., Taki, Y., Yoshizuka, N. and Luong, N. Q., 2015. Effects of various placement patterns on stability of Rakuna-IV slope: Section 5A - Nghi Son Breakwater, Report 2D physical model experiments.Google Scholar
  4. Suh, K.D., Lee, T.H., Cheon, S.H. and Matsushita, H., 2014. Stability Formula for Rakuna-IV Armoring a Rubble Mound Breakwater. Proceedings of the Twenty-fourth International Ocean and Polar Engineering Conference, Busan, Korea.Google Scholar
  5. Giang, L.T.H., 2015. Overtopping performance and stability under wave overtopping of Rakuna-IV blocks on a rubble mound slope (in Vietnamese). Doctoral Dissertation, Thuyloi University.Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  1. 1.Faculty of Marine and Coastal EngineeringThuyloi UniversityHanoi CityVietnam

Personalised recommendations