Page 146 - Moving the Earth_ The Workbook of Excavation

ROCK, SOIL, AND MUD

3.40 THE WORK

Clay. Clay fills are liable to become soft and slippery during rain. The wet surface may be bulldozed
off and replaced with dry material, or the dry material may be dumped over the mud in sufficient
quantity to carry traffic over it, and may be removed later. If rain is anticipated, the original fill
may be left low, to leave room to cover it.
If fill is coming from two or more sources, it is sometimes possible to keep the clay in lower
parts of the fill and the better material on the top.
Area Dumping. If trucked soil is too wet to be stabilized and will not support trucks after being
spread, and if the ground (or lower layer of the fill) is passable to trucks, area dumping may be
resorted to. A calculation is made of the amount of fill needed in a given area and the amount of
each incoming load. Allowance must be made
for shrinkage of the soil upon drying and
after compaction, and the number of loads
required in such an area may be found by
dividing the cubic yards required by the
corrected yardage of a truckload.
The trucks may then dump their loads in
piles which can be left to dry, then be spread
and compacted.
Buried Mud. If it is impossible to truck in
the area to be filled, the mud must be cov-
ered as it is dumped with a layer of dry fill,
gravel, or rock sufficient to support the trucks.
Sometimes the mud will support a bulldoz-
er which can roughly grade the soft fill. The
dry surfacing is advanced close behind the face
of the mud fill, trucks dump the mud at its
edge, and the dozer pushes it over the face,
digging down sufficiently to allow place-
ment of more surfacing. See Fig. 3.30.
In such mud work, it is advisable to have
at least two dozers, so that the one working
in mud can be promptly rescued if stuck.
Under extreme conditions two dozers may be
attached to each other, back to back, by a
chain or cable. As one of them pushes mud
toward the face, the other backs up toward it,
keeping the line slack. When the pusher backs
up, the other one pulls it to firm footing. The
helper Cat need not have a dozer, and prefer-
ably should be larger than the one doing the FIGURE 3.30 Two-layer fill.
work. Wide tracks are a big asset in mud.

STUCK MACHINERY

The next problem to consider is how to rescue machinery that has sunk so far into mud that it cannot
move under its own power. The easiest and most attractive method is to stretch a chain or cable
to some power source and pull it out. Often there is no such power available; but if there is, it