Figure 2.6. Measurement locations for vertical velocities shown in Figure 2.5 



Figure 2.7 shows a typical plot of vertical velocity Vi/j/{gH,)''^, measured 1 

 cm outside the armor layer at various depths, versus the square root of wave steepness, 

 where v^^ is the average of the highest one-third peak velocities for the burst of regular 

 waves, g = gravitational acceleration, structure slope = 1 V:2H, and L„ = deep water 

 wave length. For simplicity, v is used instead of v,/, in Figure 2.7 and hereafter. 

 Relative laser depth, rd = djldj, is the ratio of the depth of the laser to the depth at the 

 toe, measured from the still water level. As noted by Sawaragi et al. (1982), maximum 

 non-dimensional velocities commonly occurred for collapsing to plunging breaking 

 waves. Pilarczyk and Den Boer (1983) showed minimum stability for 1V:2H slope 

 occurred for ^ = 3.3. In this case, this point occurs at {HIL^'''^ = 0.15, which is near the 



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