PART IV: CONCLUSIONS 



Toe Berm Stone Tests 



32. Based on the 2-D and 3-D wave stability test conditions and test 

 results reported herein for two-layer, randomly placed armor stone toe berms 

 on breakwater and jetty trunks and heads with a length B equal to 5 ft or 3 

 widths of W 50 stone (whichever is greater) and designed for breaking wave 

 environments where wave crests are either parallel or oblique to the berm, it 

 is concluded that: 



a. The stability number N s appears to be relatively insensitive 

 to changes in wave steepness H D /L S and relative wave height 

 H D /d s for the range of values tested. 



b. For the narrow range of relative berm length B/L-l tested, the 

 stability number shows no well-defined trend. 



c. The stability number shows a minor trend to increase with 

 increasing values of d s /L s , which indicates a small depend- 

 ency on wave length, i.e., wave period. The best defined trend 

 is the one of increasing values of N s with increasing values 

 of relative berm depth d-^d,. . The spread of the data which 

 defines this trend appears to be a function of wave period, 

 foreslope fronting structures, angle of wave attack, and 

 whether the toe berm is on the head or the trunk. These 

 secondary trends are minor relative to the trend with relative 

 berm depth, and attempts to develop multiparameter functional 

 relationships were less than satisfactory. Therefore, for 

 general design purposes, unless site-specific model tests are 

 conducted to justify higher values of N s , stability number 

 should be selected based on the lower limit curve presented in 

 Figures 14 and 15, and the individual toe berm armor stone 

 weights should range from a maximum 1.3 W 50 to a minimum of 

 0.7 W 50 . 



d. Insufficient spectral stability data are available to recommend 

 general design guidance relative to spectral H^ values. It 

 is recommended that an estimate of the maximum breaking wave 

 height associated with the selected design spectrum be used in 

 Equation 2 when sizing toe berm armor stone. 



Buttressing Stone Tests 



33. Based on the limited 2-D wave stability test conditions and test 

 results reported herein for toe buttressing stone fronting one-layer uniformly 

 placed tribars, it is concluded that a stability number N s equal to 1.5 



30 



