Josep Ramon Medina, Vicente Pardo, Jorge Molines, M. Esther Gomez-Martin


Armor porosity significantly affects construction costs and hydraulic stability of mound breakwaters; however, most hydraulic stability formulas do not include armor porosity or packing density as an explicative variable. 2D hydraulic stability tests of conventional randomly-placed double-layer cube armors with different armor porosities are analyzed. The stability number showed a significant 1.2 power relationship with the packing density, similar to what has been found in the literature for other armor units; thus, the higher the porosity, the lower the hydraulic stability. To avoid uncontrolled model effects, the packing density should be routinely measured and reported in small-scale tests and monitored at prototype scale.


mound breakwater; armor porosity; packing density; armor damage; armor unit; cubic block.

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Barron, A. 1984. Predicted squared error: A criterion for automatic model selection. In S. Farlow (ed.), Self-Organizing Methods in Modelling, 87-103, Marcel Dekker, New York.

Burcharth, H.F., and Z. Liu. 1992. Design of Dolos armour units. Proc. 23rd Int. Conf. on Coastal Engineering, ASCE, 1053-1066.

CIRIA, CUR, and CETMEF. 2007. The Rock Manual. The use of rock in hydraulic engineering (2nd edition). C683, CIRIA, London.

Figueres, M., and J.R. Medina. 2004. Estimation of incident and reflected waves using a fully non-linear wave model. Proc. 29th Int. Conf. on Coastal Engineering, World Scientific, Singapore, 594-603.

Frens, A.B. 2007. The impact of placement technique on Antifer-block stability. M.Sc. thesis, Delft University of Technology, The Netherlands.

Gómez-Martín, M.E., and J.R. Medina. 2014. Heterogeneous packing and hydraulic stability of cube and Cubipod armor units. Journal of Waterway, Port, Coastal and Ocean Engineering, 140(1), 100-108.

Holtzhausen, A.H., and J.A. Zwamborn. 1991. Stability of Accropode® and comparison with dolosse. Coastal Engineering, 15(1-2), 59-86.

Hudson, R.Y. 1959. Laboratory investigation of rubble-mound breakwaters. Journal of the Waterways and Harbors Division, 85(WW3), 93–121.

Jensen, O.J. 2013. Safety of Breakwater Armour Layers with Special Focus on Monolayer Armour Units. Proc. of Coasts, Marine Structures and Breakwaters 2013, Institution of Civil Engineers (in press).

Latham, J.P., E. Anastasaki, and J. Xiang. 2013. New modelling and analysis methods for concrete armour unit systems using FEMDEM. Coastal Engineering, 77, 151-166.

Maciñeira, E., F. Noya, and V. Bajo. 2009. Breakwater construction at the new port in Punta Langosteira, A Coruña, Spain. Execution process and technical innovation. Proceedings of Coasts, Marine Structures and Breakwaters 2009, ICE, Thomas Telford Ltd., Vol 1, 532-543.

Medina, J.R., R.T. Hudspeth, and C. Fassardi. 1994. Breakwater Armour Damage due to Wave Groups. Journal of Waterway, Port, Coastal, and Ocean Engineering, 120(2), 179-198.

Medina, J.R., M.E. Gómez-Martín, and A. Corredor. 2010. Influence of armour unit placement on armour porosity and hydraulic stability. Proc. 32nd Int. Conf. on Coastal Engineering, ASCE, 32(2010), structures.41.

Medina, J.R., M.E. Gómez-Martín, and A. Corredor. 2012. KD and safety factors of concrete armor units. Proceedings of 33rd International Conference on Coastal Engineering, ASCE, 33(2012), structures.29.

Medina, J.R., Molines, J., and M.E. Gómez-Martín. 2014. Influence of armour porosity on the hydraulic stability of cube armour layers. Ocean Engineering, 88(2014), 289-297.

Pardo, V., Herrera, M.P., Molines, J., and J.R. Medina. 2014. Placement tests, porosity and randomness of cube and Cubipod armor layer. Journal of Waterway, Port, Coastal and Ocean Engineering, 140(5), 04014017-1-9.

U.S. Army Corps of Engineers (USACE). 1984. Shore protection manual. U.S. Army Engineer Waterways Experiment Station, Coastal and Hydraulics Laboratory, Vicksburg, MS.

Van der Meer, J.W. 1988. Stability of Cubes, Tetrapods and Accropodes. Proc. Coasts, Marine Structures and Breakwaters 1988, Thomas Telford Ltd., 71-80.

Van der Meer, J.W. 1999. Design of concrete armour layers. Proc. 3rd Coastal Structures Int. Conf. A.A. Balkema, Rotterdam, 213–221.

Van Gent, M.R.A., and L. Luis. 2013. Applications of Cubes in a single layer. Proc. 6th SCAR-International Short Course/Conference on Applied Coastal Research. Paper No. 27, Lisbon.

Vincent, G., L. Tourmen, and J. Gonzalo-Vara. 1989. Diques marítimos. Revista de Obras Públicas, Sep. 1989, 657-667 (in Spanish).

Zwamborn, J.A. 1978. Dolos packing density and effect of relative block density. Proc. 17th Int. Conf. on Coastal Engineering, ASCE, 2285-2303.