THEORETICAL AND EXPERIMENTAL STUDY ON THE PLACEMENT OF A NEW CONCRETE ARMOUR BLOCK
DOI:
https://doi.org/10.11113/mjce.v27.15932Keywords:
Breakwater, packing density, placement grid, placement pattern and single layer armour.Abstract
Crablock, a new concrete armour unit has been developed and applied as single layer armour system in one damaged breakwater at UAE. Single layer concrete armour units that exist at this moment have fixed placement pattern mostly random along with designed placing grids and packing densities. The symmetrical shape of crablock makes the unit different from other existing randomly placed single layer units therefore the placement of crablock armour units is also assumed different compared to other single layer blocks. It is worth mentioning that the crablock unit is still under development therefore no design guidance exists at present for this new concrete armour block. To come up with preliminary design guidance for the placement of crablock, an experimental research has been done, which is the subject of this paper. In this laboratory study, in total fourteen placement test series were performed to familiar the placement pattern of crablock as single layer system. In order to establish a reliable dataset, three repetition tests were performed for each test series thus in total 42 tests were conducted on the placement of crablock. This paper describes small scale model placement tests to examine the placement pattern of crablock and also provides a comparison between theoretically designed and actual (measured) placement grid. Based on test results it was observed that crablock armour units can be placed in both uniform and random pattern. Uniform placement of crablock was achievable in a rectangular grid using a relatively small and smooth under layer (1/25th of the size of the armour layer). However, test results showed that a random placement can be best achieved using a conventional diamond shaped grid. Finally, from the placement tests two preferred placing patterns were appeared, a regular pattern in a rectangular grid using a relatively small under layer and a random pattern in a diamond shaped grid using a conventional under layer.References
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