Civil Engineering Reference
In-Depth Information
Figure 19.3
Compatible mechanisms.
Figure 19.4
Work done by external loads.
element of soil with unit weight
and with a total stress
p
and a concentrated load
F
at the top surface where the pore pressure is
u
. There is an increment of displacement
δ
γ
w
in the direction of the surface stress, the concentrated load and self-weight forces.
For undrained loading the increment of work
δ
E
is
δ
E
=
F
δ
w
+
pA
δ
w
+
γ
V
δ
w
(19.8)
For drained loading the water remains stationary so the work is done by the effective
stresses only; hence
δ
E
=
F
δ
w
+
(
p
−
u
)
A
δ
w
+
(
γ
−
γ
w
)
V
δ
w
(19.9)
For dry soil simply put
u
=
γ
w
=
0 in Eq. (19.9).
