Department of Civil Engineering, N-W.F.P UET, Peshawar
Design of Retaining Walls
8" 3'-4"
a
b W5
11'-6" W6
W1
3.25'
3'-6"
W2
W4 1.5'
W3 15"
9.75'
Figure 7: Cross section of retaining wall. Location of resultant (see fig. 3c) from base of retaining wall is: y = (h2 +3hh′)/3(h+2h′) = (152 + 3 x 15 x 3.33)/3 x (15 + 2 x 3.33) = 5.77′ Overturning moment (OTM) = Pay = 6.43 x 5.77 = 37.10 ft-k Calculate the weights shown in figure 7 and take their moment about toe edge. S.No. 1 2 3 4 5 6
Table 2: Weights and moments about front edge (toe) of retaining wall. γ Area (A) W = γA x (from toe) 0.15 (8/12) x 13.5 = 9 1.35 3.58 0.15 (1/2)(7/12)(13.5) = 3.94 0.591 4.11 0.15 9.75 x 1.5 = 18 2.2 4.875 0.12 3.25 x 2 = 6.5 0.78 1.625 0.12 (1/2)(7/12)(13.5) = 3.94 0.4728 4.31 0.12 5.25 x 16.83 = 88.35 10.602 7.125 ∑W=Rv =16.00 k
Prof Dr. Qaisar Ali (http://www.eec.edu.pk)
Wx 4.83 2.43 10.73 1.27 2.04 75.54
∑(Wx)= 96.84 k Page 12 of 28