Linking the units increased stability; however, they began rocking in 

 their nested positions at a wave height of about 30 feet. Thus, the 

 units were considered unacceptable, and no further stability tests were 

 conducted. 



5^ Test 5. Purpose : To determine the stability of 33- 

 and 44-ton tribar armor units (with and without the use of a linking 

 mediixm) for protection of the rehabilitated jetty head. 



Results : The linked 33- and 44-ton tribar armor units were stable for 

 the 40-foot design wave, but failure occurred when the linking medium was 

 cut to simulate breakage by abrasion. Considerable damage occurred when 

 the 44-ton units were tested unlinked using 40-foot waves. Therefore, it 

 was decided to design a tribar section stable for 40-foot waves when the 

 units were unlinked. Tribars of 65 tons were selected for these tests 

 (test 8). 



6^ Test 6. Purpose : Previous tests indicated that it 

 was difficult to obtain stability of the armor units at the shoreward end 

 area of the repair section, and that the repair section usually failed in 

 this area before the no-damage wave for the head section was determined. 

 Thus, this series of tests was conducted to determine the most practical 

 method of obtaining stability of both areas of the repair section for the 

 same no-damage wave height. 



Results : The use of a linking medium and either 33- or 44-ton tribars 

 would provide the shoreward end area with stability comparable to that of 

 the head section, provided the linking lines do not fail by abrasion. It 

 was found that migration of 44-ton tribar imits could be prevented by the 

 use of concrete or pile barriers if practical methods of constructing 

 these barriers in the prototype could be devised (Fig. 6-31). 



1_ Test 7. Purpose : To determine the stability of the 

 toe part of the test sections for the low water (SWL = 0.0 foot MLLW) 

 condition. Since the slope of the repair section was about 1:5, and the 

 design waves for the high water and low water conditions were 40 and 31 

 feet in height, respectively, the toe distance from the edge of the mono- 

 lith was critical because of the difficulty and expense of providing a 

 crane with adequate reach and lift capacity. 



Results : Tests showed that the stability of the toe armor units around 

 the jetty head at low tide was critical with respect to the design of the 

 repair section. 



8 Test 8. Purpose : To develop a stable repair section 

 with 65-ton (150 pounds per cubic foot) tribars using the selected design 

 waves of 40 feet at the +7 foot MLLW level and 31 feet at the 0.0-foot 

 MLLW level. The tribar weight of 65 tons was selected based on the re- 

 sults of previous tests, using 33- and 44-ton units, and the stability 

 equation (eq. 6-4b) . 



Results : A repair section of unlinked 65-ton (150 pounds per cubic 

 foot) tribars was found to be stable for the 40-foot design wave at +7 

 feet MLLW (stillwater level), and for the 31-foot design wave at the 

 0.0 foot MLLW (Stillwater level). 



396 



