Stable annulus of water, A, is repeatedly formed and then is repeatedly and rapidly 
impacted with high velocity steel inpactor, B. This forms a small, extremely high velocity water 
jet, C, which can be used for breaking brittle materials such as rock. In use, water is intro- 
duced through a tangential hole, D, into an annular space in acylinder, E. Surplus water is 
collected at suction hole, F, to avoid possible interference of any excess water with the 
working jet, C. 
Figure 65. Method for repeatedly forming a stable annulus of water. 
An example of local destruction of a single shot in Barre granite is 
shown in Figure 66. About 7 in.? of rock was removed with a jet of 750,000- 
psi stagnation pressure. 
Either of these special rock destruction techniques, the electron beam 
or high-velocity water jet, promises to reduce the rotation, torque, thrust, and 
atmosphere contamination common to large boring machines employing cut- 
ter bits. However, the processes by which these are applied to a solid rock face 
in acontrolled manner have not been worked out; these problems are to be 
attacked shortly. Failing successful development of suitable new control 
methods and excavation technqiues, there is at least one major improvement 
in rock bit application which might improve boring efficiency, although prob- 
ably always with relatively rapid bit dulling and replacement. A series of 
patents (Bouyoucos and Hunt, 1958, 1961, and Bouyoucos, 1964, 1965a, 
1965b) of hydroacoustic oscillators provides a method for rapidly and 
forcibly oscillating tool-steel or carbide cutters in drilling rock. The action 
is similar to that achieved with air drills but is believed to be much more 
effective on an energy use basis. More important, it can be operated with 
pressurized seawater (in a proposed design), and the discharging seawater 
can be used to flush chips from the work area. General Dynamics Corpora- 
tion controls Bouyoucos’s patents and has prepared a design of an oscillator 
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