TABLE 21 - Earth Forces and Moments 



Force Arm (from A) Moment 



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



Earth (Horizontal), Ppj = 11,^00 (lb/ft) 7.86 +90,^00 



Earth (Vertical), P^ = 6,950 (lb/ft) 2,36 +l6,U00 



280. Uplift Forces and Moments . - Uplift forces may be computed as 

 a straight line triangular variation, assuming a head of 12,5 feet at the 

 toe aii none at the heel. 



TABLE 22 - Uplift Forces and Moments 



Force Arm (from A) Moments 



(lbs» per foot) (feet) (ft. •- lbs. per ft,) 



Uplift (Vertical) 8,020 13.33 -107,000 



281. Stability Table. - Surruiaarizing the preceding j the following 

 table may be set up: 



TABLE 23 - Stability Table, Landward Overturning of Moments 



Force Arm (from A) Moments about A 



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



Concrete (Vertical) 2h,S00 7.72 +189, 000 



Earth (Horizontal) 11,500 7.86 + 90,^00 



Earth (Vertical) 6,9^0 2.36 + l6,U00 



Water (Vertical) 8,850 lii.7 +130,000 



Iv'ave (Horizontal) 28,370 -28U,000 



Uplift (Vertical) 8,020 13.33 -107,000 



TOTAI. +ii25,900 »391>000 



NET TCTAL + 3U,900 



The moments which would cause overturning around point A are negative, 

 therefore the wall is stable under wave forces, 



282. Stability Calculations. - Wall Toppling Seaward . - Maximum 

 moment causing the wall to overturn seaward would occur with no water in 

 front of the wall, and assuming a saturated backfill and a surcharge of 

 250 pounds per square foot. The earth forces and moments may be computed 



139 



