DUTCH WIDE 

 GRADATION 



DUTCH NARROW 

 GRADATION 



PERCENT LESS THAN BY WEIGHT 



Figure 58. Armor-stone characteristics of Dutch wide gradation, Dutch narrow gradation, 

 and Ahrens (1975) SPM gradation 



which provides the designer with confidence in determining the structural 

 stability and resulting performance characteristics of a given structure. 



There are numerous proprietary beach erosion control or stabilization 

 systems that function similarly to breakwaters, but are of unique geometry or 

 construction. Most of these systems are precast concrete units, concrete 

 blocks, or flexible structures such as large sand-filled bags placed in various 

 configurations nearshore or in shallow water. Most have undergone limited 

 laboratory testing and many have never been field tested. Generally, these 



Chapter 4 Structural Design Guidance 



99 



