Civil Engineering Reference
In-Depth Information
From Fig. 22.15(b), with
n
=
R
/
r
=
10, the time when settlement is complete (i.e.
when
U
t
=
1.0) corresponds to
T
v
=
1.0. Hence, from Eq. (22.28),
T
r
R
2
c
r
1.0
×
1.0
t
=
=
=
0.5 years
2
Example 22.5: Calculation of stresses and settlements in elastic soil
Figure 22.18 shows
a circular water tank at the surface of a deep bed of elastic soil. For
=
50 kPa the changes of vertical stress and the settlements for drained loading are given
by Eqs. (22.16) and (22.17).
δ
q
=
5
×
10
δσ
z
=
δ
qI
σ
=
50
I
σ
kPa
−
ν
2
E
0.25
2
)
10
3
qB
1
10
(1
−
×
δρ
=
δ
I
ρ
=
50
×
I
ρ
=
47
I
ρ
mm
10
3
10
×
where
I
σ
and
I
ρ
are given in Fig. 22.10.
(a) At point A,
z
/
a
=
0so
I
σ
=
1.0 and
I
ρ
=
1.0; hence
δσ
z
=
50 kPa
δρ
=
47mm
ν
=
(b) At point B,
z
/
a
=
1so
I
σ
=
0.65 and, for
0.25 (interpolating between the
ν
=
ν
=
data for
0 and
0.5),
I
ρ
=
0.65; hence
δσ
z
=
33 kPa
δρ
=
31mm
Figure 22.18
Settlement of a water tank on elastic soil - Example 22.5.
