therefore W = 170^ pounds per square foot. 



The maximum passive pressure p at the depth of p,Q is applied at the wall 

 back aid is given by 



Pp == -6 (^6 -^^ *-"' ^^^^ (126) 



where ^^ = 30° 



355. This active pressure at the depth of p,„ at the Xirall face is due to 

 a surcharge composed of the ground above G applied to the earth mass of height 

 h^. The surcharge in this case is 



^a = ^ H (127) 



= 80 X 2,36 = 186, U pounds per square foot 



The maximum, active pressure p„ at the depth of p, ^.^ is applied at the wall face 

 and is given by 



^a = ^6 (^6 ^ |) ^^"' (^) (128) 



356. The actual pressure p..^ is given by 



PlO " Pp ' Pa (129) 



= w^hg tan"" (—2-^) - tan- ( ^ °) ^ w^ tan^ ( ^ ^)- W^ tan"^ (—^ -) 



- Rh^ + 1705 (3) - 186. li (0.33) 

 = 21U hg + 5053 - 21U (h^ + 23.6) 

 which raaj'^ be written symbolically 



The loading diagram for this section of piling is shown in Figure 112 



357. The sura of all forces below G must equal the shear Sp at G. 

 Summing the forcesj represented by the areas GH'' Hj H'H JJ', and H«J« p,„ 



173 



