Civil Engineering Reference
In-Depth Information
0
.01
.02
.03
.04
2.0
.05
.06
.07
.08
.09
.10
.11
.12
.13
.14
.1
.1
.1
.1
.1
.20
1.8
1.6
c
H
tan
1.4
1.2
.25
tan
FS
.30
1.0
.35
.40
.45
.50
.65
.70
.80
.90
1.0
1.5
2.0
4.0
Slope angle
0.8
80
°
70
°
0.6
60
°
50
°
40
°
0.4
30
°
20
°
0.2
10
°
0
8
0
.02
.04
.06
.08
.10
.12
.14
.16
.18
.20
.22
.24
.26
.28
.30
.32
.34
c
H
FS
Figure 8.10
Circular failure chart number 5—fully saturated slope.
ratio
c/(γ H
tan
φ)
for a flatter slope of 30
◦
,in
the same way as it was found for the 42
◦
slope.
The dashed line (
C
) in Figure 8.15 indicates the
shear strength, which is mobilized in a dry slope
with a face angle of 30
◦
. Since the mobilized shear
strength
C
is less than the available shear strength
D
, the dry slope is likely to be stable.
Figure 8.15 shows the range of friction angles and
cohesions that would be mobilized at failure.
The shaded circle (
D
) included in Figure 8.15
indicated the range of shear strengths that
were considered probable for the material under
consideration, based upon the data presented in
Figure 4.21. This figure shows that the available
shear strength may not be adequate to maintain
stability in this cut, particularly when the cut is
saturated. Consequently, the face angle could be
reduced, or ground water conditions investigated
to establish actual ground water pressures and the
feasibility of drainage.
The effect of reducing the slope angle can be
checked very quickly by finding the value of the
8.6 Detailed stability analysis
of circular failures
The circular failure charts presented earlier in this
chapter are based upon the assumption that the
material forming the slope has uniform proper-
ties throughout the slope, and that failure occurs
