Abstract
ON February 2–3, 1934, a storm of exceptional severity was experienced along the northern coast of Africa and led to the destruction of more than 1,300 ft. of the recently constructed Mustapha Breakwater at Algiers. The storm and the damage done is described by Dr. B. Cunningham in Engineering of January 11. There are several moles protecting the Port of Algiers, but whereas the older ones are rubble mounds, the Mustapha Breakwater consisted of a vertical wall llm. thick with its base resting on a rubble foundation 50 ft. below mean sea-level. It was recognised as one of the finest examples of its kind. The wall successfully withstood a severe storm on December 31, 1933, when it was subject to waves 6–61/2 m. in height and 100–120 m. in length, but was completely destroyed by the storm of February 2–3, 1934. Observations made during this storm showed that the wall was being subject to the action of waves 9 m. in height, 200 m. long and with a period of 133/4 seconds, and photographs taken show unbroken masses of water 2–6 m. thick passing over it. There were three stages in its destruction: (1) erosion of the bed of the sea in front of the rubble foundation, (2) the sudden removal of the rubble foundation by one or more great waves, and (3) the excavation by the sea of a trench into which the wall collapsed. It has been generally thought, says Dr. Cunningham, that a level of about 40 ft. below the sea-surface marked the limit of appreciable dislocation of rubble foundation mounds by wave action, but this view now needs reconsideration, and it is clear that the effective suction of a back draught following wave stroke may extend to depths far below the accepted standard. Fortunately, the failure of the mole did not lead to damage to shipping in the harbour. It has now been decided to replace the wall at once with a breakwater of the classic mound type.
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Effect of Rough Seas on Marine Structures. Nature 135, 143 (1935). https://doi.org/10.1038/135143b0
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DOI: https://doi.org/10.1038/135143b0