The 1984 Major Rehab of the Muskegon Harbor, MI South Breakwater: An Extreme Example of Misguided Design of a Stone Structureby Charles N. Johnson, US Army Corps of Engineers, Chicago, United States,
Abstract: It can be inferred from the Shore Protection Manual that the stability of any coastal structure is increased in proportion to the weights of the armorstones. The south breakwater at Muskegon Harbor, MI was built in 1931 of 28 concrete caissons, each 54 ft. long. As scour protection, both faces of each caisson were covered with 1 to 5 ton riprap. A bedding apron 4 ft. thick of quarry run stone extended 25 ft. beyond the riprap toe. In 1983 it was decided that 13 ton stone should be used for repairs, even though the 1 to 5 ton stone had stayed in place very well for 50 years. The 13 ton stone has proven to be of disappointing durability since construction in 1984. At least 300 stones are badly fractured or missing as of 1991. It is concluded that large stones do not buy stability if their durability is poor.
Subject Headings: Rocks | Breakwaters | Rehabilitation | Harbor facilities | Caissons | Riprap | Coastal management | Material durability | Structural stability | Michigan | North America | United States
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