Page 202 - Buried Pipe Design

176 Chapter Three

Vertical Deflection
Vertical Soil Pressure, lb/in 2 B A B A
Horizontal Deflection

Pipe Deflection, %
Figure 3.58 Vertical soil pressure versus pipe deflection. (A) Soil box data, 80 percent
relative compaction; (B) FEA, no compaction simulation.

Thrust Strain
Bending Strain

B

m in/in B

Strain, A

–

A
–

Position on Pipe, degrees
Figure 3.59 Pipe strain as function of circumferential position, conditions as in Fig. 3.58.
Figures 3.58 and 3.59 also show the results from the FEA for the
80 percent relative compaction homogeneous condition. Although the
load-deflection curves show much greater deformation with the loose
material than with the dense material, the actual comparison of soil
box tests with FEA tests shows that the FEA does not compare quite
as well for loose soil conditions. The pipe-strain plots shown in Fig. 3.59
also indicate a generally poorer correlation. In terms of magnitude of
the maximum strain, there is some correlation, but the overall shape