Page 236 - Moving the Earth_ The Workbook of Excavation

DITCHING AND DEWATERING

5.38 THE WORK

FIGURE 5.27 Pipe hooks.

free end slightly lower so that it can be guided into place without scraping on the bottom. This tip
is arranged by inserting the hook only partway into the pipe, or by pushing down on the free end.
If a section is not held in proper position by the bed, it should be chocked securely with stones
or blocks until several more sections are laid, or the culvert is completed. This makes it possible
to make any necessary readjustments with less work than if fill were tamped in immediately.
It is difficult to get each joint tight without considerable practice. However, it is often possible
to lay several loosely, and then push them together from an end. This may be done by a small dozer
in the trench, or by a cable threaded through the culvert to a crossbeam.
Joints. Except in informal or temporary work, joints should be cemented. This is particularly
important if water may pond above the outlet so that it will go through under pressure, which
might force it out through open joints and cause softening and channeling of the embankment.
Small pipe is cemented by wetting the ends to be joined, and troweling a rich mortar on the upper
half of the plain side and the lower half of the bell end. It is desirable to rotate the free pipe slightly,
after it is in position, to spread the cement evenly. The outer surface of the upper two-thirds can be
troweled off.
If the pipes are large enough for a person to work inside, the whole culvert may be placed dry. Oakum
is then hand-tamped into the joint cracks, and cement or bituminous mortar applied from the inside.

Ties. If foundation conditions are such that the fill may spread and pull the pipe apart at the
joints, the culvert may be held together by heavy, deep-based headwalls, or by tie lines.