Civil Engineering Reference
In-Depth Information
The force polygon is shown in Fig. 20.16(b). Scaling from the diagram, or by
calculation,
P
a
=
70 kN
Example 20.2: Coulomb wedge analysis for drained loading
The angle of friction of
the soil is
φ
25
◦
and for drained loading a suitable Coulomb wedge is formed
=
57
2
◦
to the horizontal. Figure 20.17(a) shows the
forces on the wedge. The magnitudes of the known forces are
45
◦
+
1
2
φ
=
by a slip plane at
α
=
qH
tan(90
◦
−
α
tan 32.5
◦
=
V
=
)
=
80
×
5
×
255 kN
1
2
γ
H
2
tan(90
◦
−
α
1
2
×
5
2
tan 32.5
◦
=
W
=
)
=
20
×
×
159 kN
1
2
γ
w
H
w
=
1
2
4
2
P
w
=
×
10
×
=
80 kN
1
sin
1
sin 57.5
◦
=
1
2
γ
w
H
w
×
1
2
×
4
2
U
=
α
=
10
×
×
95 kN
and the other information is
T
=
U
) tan 25
◦
(
N
−
T
w
=
P
tan 15
◦
The force polygon is shown in Fig. 20.17(b). Scaling from the diagram or by
calculation,
P
a
=
245 kN
Figure 20.17
Forces on sheet piles in Figure 20.15 for drained loading.
