PART III: TEST RESULTS 



Sea-Side Structure Slope = IV on 2H 



19. Stability test results for dolos and tribar overlays constructed on 

 a lV-on-2H slope are summarized in Table 1. Presented herein are experimen- 

 tally determined K's as functions of d/L and relative wave height (H/d) . 

 The stability coefficient, K , is determined from the Hudson formula, i.e., 



yh' 



w = 



^ K^(S - 1)-^ cot a 

 D a 



where 



K = stability coefficient 



S = specific gravity of armor unit 

 a = reciprocal of breakwater slope 

 Armor units were placed randomly in two layers and the number of armor units 

 per given surface area was equal to that presently recommended for new con- 

 struction in EM 1110-2-2904, "Design of Breakwaters and Jetties" (Headquar- 

 ters, Department of the Army 1986). Photos 4-10 show typical after-testing 

 conditions of structures. 



20. Figures 2 and 3 present K^ as a function of d/L and H/d , re- 

 spectively. These data show dolos stability to be sensitive to both d/L and 

 H/d with minimum stability occurring at the lower values of d/L and higher 

 values of H/d , i.e., longer wave periods in shallower water. These trends 

 are consistent with those observed by Carver (1983) for dolos used in new con- 

 struction. Influences of H/d and d/L on tribar stability do not appear to 

 be significant in the present data. The minimum IC observed for tribars is 

 equal to that obtained for new construction and to that observed for dolos is 

 about 15 percent less (12.8 versus 15). 



Sea-Side Structure Slope = IV on 1.5H 



21. Stability tests were initiated at the lV-on-1.5H slope using dolos 

 armor units randomly placed in two layers. Results of these tests, summarized 



13 



