conducted (with the type of plan and tests conducted based on the results 

 of the preceding tests); the purpose and summary of results for each test 

 series are given below. 



1 Test 1. Purpose : To determine the relative stabil- 

 ity of unlinked armor-unit repair sections using cubes, tetrapods, and 

 tribars. (A supply of dolos armor units was not available at test time, 

 and the trilong unit was devised later.) 



Results : The stability of the armor units for the conditions tested 

 (i.e., cot a = 5, nonbreaking waves, and an SWL = +7 feet MLLW) in terms 

 of K in the stability equation, was: 



Armor unit Weight ^D=o ' ^ 



(ton) (ft) 



Cube 100 22 0.7 

 Tetrapod 28 23 2.7 

 Tribar 23 29 6^ 



'Ht-j_ is the model selected design wave height for the no-damage criterion. 



Based on these results, further testing of cubes was limited to determin- 

 ing whether the linking medium would make the use of cubes feasible (test 

 2), and no further tests of tetrapods were made. 



2 Test 2. Purpose : To determine the feasibility of 

 linking 100-ton cubes in clusters and the effects of armor-unit linking 

 on the stability of the repair sections using cubes. 



Results : Tests showed that the free-fall launching of cubes would not 

 result in an armor toe distance seaward of the monolith sufficient to en- 

 sure a stable cover layer, and that stability of the section was not in- 

 creased by using more than three units in a cluster when the units are 

 launched by the free-fall method (Fig. 6-30). 



3 Test 3. Purpose : To determine the best arrangement 

 of tribar armor units with and without linking lines. The largest tribar 

 armor unit available at test time (23-ton unit) was used. 



Results : Tests showed that 23- ton tribars, when properly linked, could 

 provide the desired protection to the structure head. However, consider- 

 able rocking movement of the nested armor units began at a wave height of 

 about 34 feet. Thus, the possibility of abrasion failure of the linking 

 medium, and the problems in placing the units in the field in the manner 

 used in the model, made this plan unacceptable. 



4_ Test 4. Purpose : To determine the stability char- 

 acteristics of the trilong armor unit (for both the linked and unlinked 

 conditions) used to form the protective cover layer of the rehabilitated 

 jetty head. Units of 28 tons were used in the tests. 



Results : The maximum wave height for which two layers of the 28-ton 

 (150 pounds per cubic foot) trilong armor units, randomly placed, were 

 stable on the 1:5 slope was 21 feet, corresponding to a K of 2.1. 



394 



