Page 138 - Moving the Earth_ The Workbook of Excavation

ROCK, SOIL, AND MUD

3.32 THE WORK

There are three principal techniques: One is to blast a ditch along the right of way, then dump
fill in it. Another is to build the road, or a section of it, on top of the swamp and blast the muck
from under it. The third, toe shooting, consists of making a big heap of fill and blasting the mud
ahead and to the sides from under that.

Ditch Shooting. The tables in Fig. 3.23 give average loading requirements for various types of
open-ditch blasts. Figure 3.24 shows how to load for rather narrow ditches, which are used chiefly
for drainage, or to make possible placing of an earth dike to cut off movement of water or mud.
It will be noted that the nature of the mud is very important in determining the size ditch which
will be obtained from a given charge.
It should also be remembered that water counts as soil in loading calculations.
Blasting techniques for wider ditches, which are used to remove muck to secure a firmer base
for road fills, are indicated in Figs. 3.25 and 3.26, which show the cross section of relief methods.
The charges should be 50 or 60 percent straight dynamite, at least 4 inches below the surface,
and covered with mud or water. The blasting cap should be in a stick of dynamite at or near the

FIGURE 3.23 Tables for mud blasting.