maximum measured velocity for the waves with f= 2 s. The peak vertical velocities for 

 given wave period decreased with increase of rd in this figure. 



Vertical Velocity at Armor Surface 



0.6 



0.5 



g 0.4 



1 0.3 



^ 0.2 



0.1 







toe depth = 24 cm 







■ 









■ 



• 





a. . . . 





• 











■ • 









o 



. M 











• 



▼ 



D 



o 















■ 





O 





V 



^ 1 1 



H 1 



-H 1 



4 1 1- 





0.05 0.1 0.15 0.2 0.25 0.3 



o T=1, rd=0.36 - T=2, rd=0.36 ° T=1, rd=0.5 

 • T=2, rd=0.5 ' T=1 , rd=0.7 ▼ T=2, rd=0.7 



Figure 2.7. Maximum vertical velocity versus the square root of wave steepness for 

 wave periods T= 1 and 2 s and relative depths rd = 0.36, 0.5, and 0.7 



2.6 Incipient Motion Prediction 



The previous experimental results indicated that one of the dominant 

 incipient motion modes was due to the vertical force occurring under the steep wave 

 front. The balance of forces for vertical incipient armor motion with no external 

 restraints yields the equality between the submerged armor weight and the vertical fluid 

 force; W = F^. The vertical force at the steep wave front can be described by the 

 Morison equation (Morison et al. 1950). 



22 



