Page 178 - Moving the Earth_ The Workbook of Excavation

BASEMENTS

4.18 THE WORK

FIGURE 4.17 Large shovel in small basement.

A 30 40 basement, 6 feet deep, can be dug as shown in Fig. 4.17. A ramp must be dug outside
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the excavation line with a slope, usually 3 ⁄ 2 or 2 ⁄ 2 on 1, which the shovel can climb when the job
is finished.
The spoil piles can be pushed back from the edge of the hole to some extent by crowding against
them with a closed bucket.
The walls of the hole tend to slope in at the bottom, and to be somewhat jagged because of the
different angles at which the bucket cuts them. Both of these features can be reduced or eliminated
by careful digging, but extra time will be consumed.
Clamshell. Clamshells are not ordinarily used in this type of excavation because they do not
move as many yards per hour as competitive types. However, they turn out as accurate a job as a
backhoe, and for small, deep excavations, will do the work more cheaply than a bulldozer.
Digging is done from the top so that no ramps are required.
An edge may be cut with the tracks parallel with it, and the tagline chains attached to one jaw,
or with the tracks at right angles to the digging line, and the tagline on both jaws. Either of these
arrangements will permit cutting straight-sided trenches along the outer lines. The center is best
cut in layers, or in sections behind completed edges.
A medium- or heavy-duty bucket should be used. The spoil may be placed in isolated piles, in
windrows, or in trucks as desired.

MULTIPLE BASEMENTS

In many residential developments, small houses are built close together in straight rows. Under
such circumstances, it may be economical to dig a wide trench straight through the block, and
backfill between the houses after the foundations are built.
In Fig. 4.18 the digging is done by a dragline or a large hydraulic backhoe or front shovel
which piles the spoil on both sides. Materials for foundations are trucked and piled on the floor
of the trench. After the foundations are up, the piles are bulldozed around and between them, and
the surplus used to build up the grade throughout the area.