Civil Engineering Reference
In-Depth Information
T
2.5 m
c
1
s
u
50 kPa
50 kN/m
2
(upper cohesive soil layer)
c
2
0 kPa
0 kN/m
2
(liquefied soil layer)
N
c
5.5
(using Fig. 8.8 with
T
B
2.5
1.0
2.5 and
c
2
c
1
0)
Using the Terzaghi bearing capacity equation to calculate
q
ult
gives
q
ult
cN
c
s
u
N
c
(50 kN/m
2
) (5.5)
275 kN/m
2
Q
ult
q
ult
B
(275 kN/m
2
) (0.8 m)
220 kN/m
Q
ult
220 kN/m
___
_________
44
kN/m
FS
Q
or
Q
5
e
M
__
Q
M
eQ
0.1 (44)
4.4 kN
m/m
Use the lower values of
Q
34 kN/m and
M
3.4 kN
m/m calculated from the strip
footing using the Terzaghi bearing capacity equation.
Spread footing using Terzaghi bearing capacity equation:
M
__
e
Q
0.30 m
(for middle third of footing,
e
cannot exceed 0.33 m,
so
e is
within middle third of footing)
T
2.5 m
c
1
s
u
50 kPa
50 kN/m
2
(upper cohesive soil layer)
c
2
0 kPa
0 kN/m
2
(liquefied soil layer)
B
2 m
N
c
3.2
(for spread footing, using Fig. 8.8 with
T
B
2.5
2
1.25 and
c
2
c
1
0)
Use the Terzaghi beairng capacity equation to calculate
q
ult
:
1
0.3
B
__
q
ult
s
u
N
c
L
1.3
s
u
N
c
1.3(50 kN/m
2
)(3.2)
208 kN/m
2
FS
q
ult
q
or
q
208 kN/m
2
_________
41.6 kN/m
2
5
q
Q
(
B
6
e
)
__________
B
2
41.6 kN/m
2
Q
[2
(6)(0.3)]
______________
(2)
2
Q
43.8 kN/m
