Page 155 - Trenchless Technology Piping Installation and Inspection
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Pipe and Pipe Installation Considerations 121
the trench walls, and placed soils (for bedding and backfilling) at
locations below and around the pipe. Ideally, installation of placed
soils should achieve a state as close to the in situ state of soils as
possible. However, this is practically impossible to achieve and
appropriate compaction methods are needed. A typical layout of a
trenched pipe installation and the associated terminology are illus-
trated in Figs. 4.1 and 4.2 and described in Table 4.1.
Excavated trench width
Final backfill
6 to 12 in.
Initial backfill (150 to 300 mm)
Pipe embedment Springline Pipe zone
Haunch zone
Haunching Foundation
(may not be required)
Bedding
FIGURE 4.1 Typical cross-section of an underground pipeline installation for fl exible
pipe. (Source: ASTM D2321, 1989.)
Top of the pipe
Crown
Invert
Haunch
zone Bottom of the pipe
FIGURE 4.2 Pipe cross-section terminology.
