Civil Engineering Reference
In-Depth Information
20
σ
hen1
σ
hen3
σ
hen6
σ
hen10
σ
hen15
σ
hen20
Coulomb
ASCE 7-98
BOCA, SBC, IBC
K0
15
10
L
b
= 10 ft
φ
= 30
o
5
S
c
/S
b
= 1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
σ
h
, kips/ft
2
Fig. B.3
Lateral Earth Pressure at Expansion Cycle (φ = 30º, All Bays, L
b
=10 ft, S
c
/S
b
= 1)
Fig. B.3 indicates that the lateral earth pressure developed in the soil mass at
the end of the last expansion cycle increases with the increase in the number of
bays (or length of the rigid frame). The earth pressure found behind the single and
3 bay frames, for instance, is found to be comparable to the lateral soil pressures
prescribed by the major building codes and the pressure determined using Cou-
lomb's active pressure theory. The pressure found behind the 15 and 20 bay
frames, on the other hand is found to exceed the lateral earth pressure at-rest for
the predominance of the backfill height.
The bending moment diagrams for the retaining wall at the end of the backfill
stage and last expansion cycle are shown in Fig. B.4 and B.5.
20
L
b
= 10 ft
φ
= 30
o
M
bn1
M
bn3
M
bn6
M
bn10
M
bn15
M
bn20
15
S
c
/S
b
= 1
10
5
0
-35
-30
-25
-20
-15
-10
-5
0
5
Retaining Wall Moment, M, kips-ft
Fig. B.4
Retaining Wall Moment at Backfill Stage (φ = 30º, All Bays, L
b
=10 ft, S
c
/S
b
= 1)
