Question

A concrete retaining wall supporting a cohesionless backfill and surcharge pressure q=250 lb/ft is shown in the figure (assume yo=150 lb/ft?, Yw=62.4 lb/ft?): a. Calculate the factor of safety against sliding b. Calculate the factor of safety against overturning Tell II c'=0, O'=320 Y=122 lb/A? 20ft $ 13 c'=0, O'=320 Y=128 lb/ft? 4ft 2ft 3 ft | 21 | 8ft '=0,'= 380 Y=128 lb/ft?

Answer 1

c-o, p=32 8=122 1b/ft² c=0, 0 = 32' 8 = 128 16/4t ² Poisto Hitet =128-101448 For d'= 32 = Angle of friction of backfill soil KA = tem (45 - 2) = tem (45 - 32/2). = 0.31 The active earth pressure acting on the wall due to backfill and surcharge load Pa = 28 KA + KAR = x1228 0.31* 1097 x (128-62.4) 40.31x ten] + 0.31 x 250 3961.42 15/ft Sum of horizontal forees acting on the wall. = P = P = 396 1.42 (blfo = It

calculating total vertical loads and Resisting moment about o section freelft) unit weight Leves Arm weight (26lft) (26 Resisting moment (16-fffft) 25350 13 x 2 = 26 150 3900 € 26x150) 13/2 = 6.5 Itx(2-1)+22 150 1650 x1 +3= 1 6050 هه اولى 1 X 22 - 22 150 3300 14850 8x12 = 96 4 5 a = 4.5 134.2486 1128 - 62.4 = 65.6 122 6297.6 18 x 10 = 80 9760 56678.4 87840 Zv=24907.6 T EMR = 190768.4

(6 factor of safety against over turning &=IMR ZMO IM = Sum of the overturning moment about toe IMO =(2H) x 4 = 396114242463 = 31691.36 lb-ft fra EM = sum of resisting moment = 190768.4 lb-fffff about toe - F. =- 190768.4 31691.36