Mining or in situ disintegration of hard material – Processes – Directly applying heat or vibration
Patent
1980-11-13
1982-12-14
Purser, Ernest R.
Mining or in situ disintegration of hard material
Processes
Directly applying heat or vibration
299 16, 299 17, 299 20, 166308, E21C 3712
Patent
active
043635180
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a rock bed preliminary fracturing method and an apparatus for preliminary fracturing rock beds by drilling a hole in the rock bed then injecting water under high pressure into the drilled hole.
In recent years, the capacity of the ripper device has been improved with the development of large-sized bulldozers to such an extent that rock beds with an elastic wave propagating speed (Vp) of about 2,500 m/s can be excavated. However, on the surface of the earth, there are a great many hard rock beds with Vp of 2,000 to 4,000 m/s, and so a greater part of them has been excavated by means of blasting. In recent years, however, the restriction on the use of blasting process has become severe year by year from the viewpoint of safety and public hazard, and so it is presupposed that a mechanical fracturing process will be required in place of the blasting process.
However, in order to excavate such hard rock beds by means of the ripper device only, a very large-sized powerful bulldozer is required, but in view of technical, economical and operability aspects, it is not advantageous to carry out the excavation work by a mere combination of such large-sized bulldozer and ripper device. If, prior to ripping, pressurized water is injected into natural cracks of the rock bed to be excavated so as to expand such cracks thereby weakening and reducing the strength of the rock bed, and thereafter ripping thereof is made, then even rock beds with Vp of about 4,000 m/s can be excavated by means of a currently employed middle-sized ripper device, and therefore this excavation process is advantageous in both technical and economical aspects.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and an apparatus for preliminary fracturing a rock bed by injecting a highly pressurized high viscosity fluid or pressurized water into a drilled hole of the rock bed.
Another object of the present invention is to provide a method of fracturing a rock bed by ripping after the rock bed is preliminary fractured by injecting a highly pressurized high viscosity fluid or pressurized water into a drilled hole of the rock bed.
A further object of the present invention is to provide an apparatus for preliminary fracturing a rock bed which is capable of continuously performing a drilling of the rock bed and a preliminary fracturing of the rock bed by injecting a highly pressurized high viscosity fluid or highly pressurized water.
In accordance with an aspect of the present invention, there is provided a preliminary fracturing method of a rock bed, comprising: drilling a hole in said rock bed to be fractured by means of a drilling rod, said drilling rod having a bit or cutter blade mounted thereon at the leading end thereof and a passage formed therein along the entire length of said rod, said passage leading to a nozzle formed in said bit; sealing a leading end portion of the drilled hole by a powder material such as rock muck or sand with said drilling rod remaining inserted in the hole, said leading end portion including said nozzle; spouting a highly pressurized viscosity fluid from said nozzle thereby allowing said viscosity fluid to intrude into cracks existing in said rock bed and clogging them, and further conntinuously spouting said highly pressurized viscosity fluid to expand said cracks and to produce a lot of new cracks in said rock bed.
In accordance with another embodiment of the present invention, after clogging the cracks existing in the rock bed, spouting of the highly pressurized fluid is stopped and then highly pressurized water is spouted from said nozzle to expand the cracks in the rock bed. This embodiment can be usable where cracks existing in the rock bed are neither big nor many in number.
In accordance with another aspect of the present invention, there is provided an apparatus for preliminary fracturing a rock bed, comprising: a guide member adapted to be mounted on a construction vehicle; drifter means movably mounted on s
REFERENCES:
patent: 1979802 (1934-11-01), Kinley
patent: 2104579 (1938-01-01), Bennett
patent: 4193634 (1980-03-01), Nakamura et al.
patent: 4215001 (1980-07-01), Elphingstone et al.
patent: 4280735 (1981-07-01), Lobbe
Akanuma Shigetake
Nakamura Joji
Kabushiki Kaisha Komatsu Seisakusho
Purser Ernest R.
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