Influence of placement technique on double-layer cube armor stability with steep foreshore slopes

María Piedad Herrera, Ainoha Hoyos, Jorge Molines, Josep R. Medina

Monday 29 june 2015

16:45 - 17:00h at Asia (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 3E. River engineering

The first concrete armor units used in the 19th century were conventional cubes and parallelepiped blocks. Cubic blocks have high structural strength, high production rate and easy handling with pressure clamps. However, their main disadvantage is the low hydraulic stability due to their tendency to face-to-face fitting which produces Heterogeneus Packing (Gómez-Martín and Medina 2014). Armor units may be placed uniformly, patterned, oriented, or randomly. Armor units, such as conventional cubes, parallelepiped blocks, Antifer cubes, and Cubipods are usually placed randomly. However, armors with conventional cubes placed in a fixed pattern also exist like the cube revetment of the Maasvlakte 2, recently constructed in Rotterdam (Loman et al., 2012). In order to analyze the influence of the placement technique on double-layer cube armor stability, 2D physical model tests were conducted in the wind and wave flume of the Laboratory of Ports at the Universitat Politècnica de València. Two small-scale models with cubes placed randomly and in patterns were constructed. The tested models corresponded to mound breakwaters with low overtopping rates. Irregular wave trains were generated with a 10% steep foreshore slope. Each group of tests was defined by the water level and the peak period. For each water level and wave period, the significant wave height was increased while the waves broke before reaching the structure due to depth-limiting conditions. Fourteen wave gauges and four pressure sensors were placed along the flume to measure the surface elevation. Armor damage was calculated after each test using the Virtual Net method described by Gómez-Martín and Medina (2014). Results of armor damage were compared for both patterned and randomly placed cube armors. The toe berm damage was also measured and the influence of the water depth on toe and armor damage was determined. References Gómez-Martín, M.E. and Medina, J.R. (2014). Heterogeneus Packing and Hydraulc Stability of Cube and Cubipod Armor Units. J. Waterway, Port, Coastal, Ocean Eng., 140, 100-108. Loman, G.J.A., Hofland, B., Van Der Biezen, S.C., Poot, J.G. (2012). Integral design of hard sea defense of Maasvlakte 2 Part II: Physical model testing of cube revetment and reef. 4th Conference on the Application of Physical Modelling to port and Coastal Protection.