Civil Engineering Reference
In-Depth Information
Once the values of
C
a
and
C
p
are determined, the total horizontal pressures,
H
a
and
H
p
, can be calculated as being equal to the areas of the respective triangular pressure
diagrams. For instance, with reference made to Figure 13.7, the value of the active
pressure is
(
2
)(
p
a
)(
h
)
(
2
)(
C
a
wh
)(
h
)
H
a
C
a
wh
2
2
H
a
and, similarly,
C
p
wh
2
H
p
2
In addition to these lateral pressures applied to the retaining wall, it is considered
necessary in many parts of the country to add the effect of frost action at the top of the
stem—perhaps as much as 600 or 700 lb per linear foot in areas experiencing extreme
weather conditions.
13.6
FOOTING SOIL PRESSURES
Because of lateral forces, the resultant of the horizontal and vertical forces
R
intersects
the soil underneath the footing as an eccentric load, causing greater pressure at the toe.
This toe pressure should be less than the permissible value
q
a
of the particular soil. It is
also desirable to keep the resultant force within the kern or the middle third of the foot-
ing base.
Retaining wall for United States Army Corps of Engineers. Colchester, Connecticut.
Constructed with precast interlocking reinforced concrete modules. (Courtesy of Doublewal
Corporation.)
