From Table 7-6 , the maximum force on the example pile occurs when 



(20° < e < 40°); 



F - 102 kN (22,930 lb) . 



m 



Note: 1 Newton (N) = 0.225 pounds of force. 

 1 kN = 1000 N. 



*************************************** 

 *************** EXAMPLE PROBLEM 29*************** 



GIVEN: 



Two piles each with a diameter D = 1.25 m (4.1 ft) spaced 30.0 m 



(98.4 ft) apart are acted on by a design wave having a height H = 10.0 m 

 (32.8 ft) and a period T = 12 s in a depth d = 26 m (85 ft) . The 

 direction of wave approach makes an angle of 30° with a line joining the 

 pile centers. 



FIND ; The maximum horizontal force experienced by the pile group and the 

 location of the reference pile with respect to the wave crest (phase angle) 

 when the maximum force occurs . 



SOLUTION : The variation of total force on a single pile with phase angle 

 was computed from Airy theory for the preceding problem and is given in 

 Table 7-6. Values in Table 7-6 will be used to compute the maximum 

 horizontal force on the two-pile group. Compute the phase difference 

 between the two piles by equation (7-56) 



X = £ cos a = 30 (cos 30°) 



n n n 



X = 26.0 m (85.2 ft) 



n 



7-153 



