S = specific gravity of an individual armor unit or 

 stone relative to the water in which the break- 

 water is constructed, i.e., S = y H 



a a w 



Y = specific weight of water, pcf 

 Test Facilities and Equipment 



6. All of the 2-D breakwater stability tests (incident wave crests were 

 parallel to the longitudinal axis of the breakwater) were conducted in a 

 6.75-ft-wide, 4-ft-deep, and 119-ft-long concrete flume. The test facility is 

 equipped with a vertical displacement wave generator capable of producing 

 monochromatic waves of various periods and heights. 



Model Construction and Testing Procedures 



7. Based on prototype information showing that bathymetry lakeward of 

 the east breakwater is quite flat and the fact that model tests would be con- 

 ducted with nonbreaking waves, it was agreed by both NCB and the US Army 

 Engineer Waterways Experiment Station (WES) that model tests would use a flat- 

 bottom bathymetry and a breakwater toe elevation of -30.0 ft low water datum 

 (lwd). 



Selection of test conditions 



8. An swl of +4.9 ft lwd and wave periods of 7, 8, and 9 sec were 

 selected by NCB for use with a 13.4-ft design wave height and a 15.0-ft wave 

 height. The 15.0-ft wave height was selected as an extreme high-wave condi- 

 tion for which NCB wanted to know the degree of damage to a 4-ton dolos 

 design. These conditions were combined into a design storm, Hydrograph A 

 (Table 1), and an extreme event, Hydrograph B (Table 2). Additional test 

 conditions are described in PART III: TEST AND RESULTS. 



Flume calibration 



9. Prior to installation of the breakwater test section, the flume was 

 calibrated for the wave and swl conditions described in paragraph 8. Test 

 waves of the required characteristics were generated by varying the amplitude 

 and frequency of the wave generator paddle motion. Changes in water-surface 

 elevations with time (wave heights) were measured with an electrical wave gage 

 positioned in the flume where the lakeside toe of the breakwater would be 

 located. 



