(2) designed as a filter hlanket or bedding layer, it may be 

 used to prevent scouring of the natural bottom material which might 

 result in undercutting of the wall. 



(3) Piers and Wharves . Revetments at pier abutments must be 

 protected the same as any open revetment and in addition must be designed 

 to protect the abutment from loss of foundation. Piers in sandy areas are 

 subject to scour around pilings where strong currents also exist. They can 

 be protected by laying down a quarrystone blanket under the pier in the 

 scour area. 



c. Anchors . Deadweight anchors can be any object that is dense, 

 heavy, and resistant to deterioration in water. The type of ocean opera- 

 tion and the availability of materials usually dictate the shape, form, 

 size, and weight of a deadweight anchor. Common examples include stones, 

 concrete blocks, individual chain links, sections of chain links, and 

 railroad wheels. In most instances, a deadweight anchor functions simply 

 as a deadweight on the sea floor that resists uplift by its own weight in 

 water and resists lateral displacement by its drag coefficient with the sea 

 floor. The use of stone as deadweight anchors becomes increasingly im- 

 practical as the holding capacity requirement exceeds 6.7 kilonewtons 

 (1 500 pounds) . 



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