Using the recommendations for factor of safety (same as for static 

 conditions) 



Allowable impulse load = 352/3 = 117 kN (26,300 lb) 



7.1.7 Solution Summary 



The allowable short-term static holding capacity is less than the 

 allowable long-term static holding capacity and is, therefore, the gov- 

 erning condition. The allowable load is also the maximum allowable lift 

 of the subsurface buoy. 



Allowable static load = 58.7 kN (13,200 lb) 



The allowable impulse load for a duration of between 0.01 and 0.1 

 second is 



Allowable impulse load = 117 kN (26,300 lb) 



7.2 COHESIONLESS SOIL 



A CEL 100K propellant-embedded anchor is to be installed in a 

 sand seafloor to moor a large surface buoy. The 0.75 x 1.5-meter 

 (2.5 x 5-ft) sand fluke will be used. The sand has been thoroughly 

 tested and found to be well-graded, have an angle of internal friction 



of 35 degrees, be of medium density (y, = 880 kg/m 3 ; 55 pcf), and 



-3 -5 



have a permeability of 1 x 10 cm/sec (3 x 10 ft/sec). The anchor 



is scheduled to be used for 2 years. Impulse loading is not expected, 

 but passing storms will generate cyclic load conditions. The worst 

 storm is expected to create 30,000 loading cycles at about 8-second 

 intervals. In addition, each of 15 smaller storms each year is expected 

 to create about 20,000 loading cycles. The site is located about 40 km 

 (25 miles) from an active earthquake fault zone with a maximum ex- 

 pected earthquake of magnitude 7. To assist the mooring designer, 

 determine the static holding capacity and provide analysis of the dy- 

 namic loading limits or effects. 



65 



