Page 230 - Moving the Earth_ The Workbook of Excavation

DITCHING AND DEWATERING

5.32 THE WORK

FIGURE 5.21 Culvert headwalls and grades.

of the waterway down from the discharge end should be as great as that above the inlet, for a long
enough distance that it will not silt up.
If the culvert is on fill or a foundation which is expected to settle, it may be laid in a vertical
curve, known as camber (see Fig. 5.21), or so as to include a vertical angle. In each case, a slight
gradient is used at the inlet end and a steeper one toward the outlet. Center settlement will tend to
straighten out the passage.
Disjointing. If a fill settles unevenly, or part of it moves laterally, any culvert that is in it will
be put under tension. Such forces generally are not sufficient to break pipe, but they are apt to pull
apart the joints.