168
Passive earth pressure
b
K
§
©
¨
·
¹
¸
q
tan
2 45 2
)
(9.23)
Use Eqs. (9.22) and (9.23) to find the lateral earth pressure the solid piles must
support:
P
hk
EM
s
apiles
lbf ft
§
©
¨
·
¹
¸
q
q
b
,
/
. tan
.
120
6 0
45
21
2
340 12
3
2
8 8
2
lbf ft
/
To determine the type of steel beams required for the soldier piles, we have taken
the bending moments about the tributary area of the piles:
6 ft
6 ft
bottom
P=2040 lbf/ft
soil pressure
At ±= 6ft × 6 ft
= 36 ft 2
M =
M = (
(340.128 2 )(6 ft)
2
) (
6 ft
3
) = 2040.768 ft-lbf/ft
Piles
Soil pressure
w
M= 2040.768 ft-lbf/ft
Soil pile spacing = 6ft
Side elevation
M
§
©
¨
¨
·
¹
¸
¸
§
©
¨
·
¹
¸
340 128
6
2
6
3
2040 768
2
.
/
.
/
lb ft
ft
ft
ft lbf ft
The moment is a distributed moment applied to the base of the tributary area of
each soldier pile. Therefore, the moment is 2040.768  ft  lbf per foot. The total
moment on the soldier pile (at the base) is
M M
0
6
2040 768
6
12 244 61
ft
ftlbf ft
ft
ftlbf
.
/
,
.
9 Invisible Roads and Transportation Engineering