Civil Engineering Reference
In-Depth Information
Figure 19.25
Equilibrium stress field for the trench in Figure 19.23.
(b) Lower bound. Figure 19.25(a) shows a typical element in an equilibrium stress
field and Fig. 19.25(b) is the corresponding Mohr circle of total stress. From
these,
σ
=
q
+
γ
z
=
80
+
20
z
z
σ
h
=
σ
−
2
s
u
=
(80
+
20
z
)
−
(2
×
40)
=
20
z
z
Hence, integrating over the height of the trench,
H
1
2
5
2
P
l
=
=
×
×
=
20
z
d
z
20
250 kN
0
Example 19.2: Drained bearing capacity of a foundation
Figure 19.26(a) shows a long
foundation, 3mwide and carrying a load
V
per metre out of the page, buried 1mbelow
Figure 19.26
Loads on a foundation.
