TABLE 20 - Wave Forces and Moments 



Force 



Arm (A) 



Moment about A 



(lbs. per fto) 



Wave (Horizontal) - 28, ,370 

 Water (Vertical) - 8,8^0 



(feet) (ft. -lbs. per ft.) 



-281|,000 

 lij..7 +130,000 



279. Earth Forces and Moments » - For stability calculations it 

 will be assumed that the backfill is unsaturated. Then the total earth 

 thrust is given by 



j£ (Csc (JZJ + 9)) fsin (9-0) 



I (1 + n) 'fsin ^) 



where 



, ,h + 2h'N 



n j°t /sin (0*0} sin 

 ""y sin (0 4- Q) sin 9 



(67) 



(68) 



h' £ ¥ 

 w 



and for this wall 



W s 2^0 pounds per square foot = the surcharge load 



w s 120 pounds per cubic foot = the backfill unit weight 



h s 20 ft. ^ the backfill height 



90 + tan""L cZ) 

 "20^ 



10U° 2« 



the wall backface angle with 

 the horizontal 



s 2S^ m the backfill internal friction angle 



-1 



I7C 



the backfill wall friction angle 



"^ H above the base 



This thrust will act at a distance (0„375 + ~-^-7c- 



and at an angle (9 ■= 90 + 02_) with the horizontal; By resolving P into 

 horizontal (Pj|) and vertical (P-y) components we may find the thrust 

 and moments about Ao These are as follows; 



138 



