Civil Engineering Reference
In-Depth Information
Friction at bottom of block
(
N
W
) (tan 22°)
(9000
7500) (tan 22°)
6670 lb
For passive resistance along front side of block,
k
p
tan
2
(45°
1
)
tan
2
[45°
1
2
(33°)]
3.39
Eq. (10.4)
2
Passive pressure at depth of 4 ft
k
p
t
D
3.39 (120 lb/ft
2
) (4 ft)
1630 lb/ft
2
Assuming block slides out from soil (i.e., passive resistance only at a depth of 3 to 5 ft
below ground surface), we find
Passive resistance
2 (5) (1630 lb/ft
2
)
16,300 lb
Neglecting friction along sides of block, we therefore find
Total lateral resistance
top friction
bottom friction
passive resistance
3640
6670
16,300
26,610 lb
26.6 kips
Earthquake analysis:
If all the soil behind the sheet pile wall were to liquefy, then the
total lateral resistance of the anchor block would equal zero (i.e., for liquefied soil, friction
angle is 0°, hence top friction and bottom friction are zero and passive resistance is zero).
The anchor block will also tend to sink into the liquefied soil.
10.14
Static analysis:
k
A
tan
2
(45°
1
2
)
tan
2
[45°
1
2
(32°)]
0.307
From Fig. 10.10,
h
0.65
k
A
t
H
0.65 (0.307) (120) (20)
480 lb/ft
2
Resultant force
h
H
480 (20)
9600 lb/ft
Earthquake analysis:
a
max
____
g
0.20
a
max
____
2
k
1
⁄
2
H
2
t
Eq. (10.7)
P
E
1
g
2
(0.307)
1
⁄
2
(0.20) (20
2
) (120)
1
2700 lb/ft
10.15
Static analysis:
t
H
120 (20)
____
________
N
0
c
300
8
Therefore use case (
b
) in Fig. 10.10.
m
(4
c
)
______
k
A
1
t
H
