Table 12
Stability Coefficients for Stone Revetments
Armor Unit
Quarrystone
Smooth rounded
2.1
Rough angular
3.5
Graded riprap
2.2
Tables 13, 14 and 15 contain solutions for Equations 17 with an illustrative example of their use.
If uniform quarrystone is used, the individual stones should range from 0.75W to 1.25W with
75 percent of the stones weighing W or more. For graded riprap, W corresponds to W50 min and the
wave height is less than five feet.
If a graded stone filter is employed, it may be significantly more fine-grained than the armor layer.
This may require the use of an intermediate layer of stone between the armor and the filter. This layer
should consist of units about 1/10 the weight of stone in the armor layer. This intermediate layer is also
recommended wh6n a filter cloth is employed because it provides bedding and resists tearing or
puncturing of the cloth under the heavy armor stone.
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