Hydraulic and earth engineering – Earth treatment or control – Rock or earth bolt or anchor
Patent
1993-02-19
1994-12-20
Reese, Randolph A.
Hydraulic and earth engineering
Earth treatment or control
Rock or earth bolt or anchor
405248, 405249, 4052591, E21D 2002, E21D 2100
Patent
active
053741404
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a drillable support bolt suitable for use in the support of an engineering or mining excavation. Whilst the invention is according to one embodiment directed towards and is primarily described with reference to a drillable support bolt for use in coal mines, it is anticipated that the invention is suitable for use in a variety of mining applications and can generally be used for the artificial support of soils, clays and rocks following and/or prior to excavation.
BACKGROUND
A large number of roof support systems exist for use in underground mines (coal and metalliferous) and slope stabilisation.
The principal means of operation of these existing systems involves the development of a hole into the material being supported and the later introduction of a dowel or bolt. This bolt is fixed into the ground (incl. rock) using a range of systems. The fixing system is normally indicated in the name of the bolt system, for example: two part resin. wall (along its length) is forced into the hole, and remains in place due to the friction of the bolt with the sides of the hole. is subsequently filled or had been filled with inorganic cement grout. The bolt is fixed in place when the grout sets. hole and high pressure water is used to inflate the bolt to a size which holds it firmly in place in the hole. place through the action of a wedge driven in to the end of the bolt at the end of the hole. place through the action of an internally threaded conical nut forcing serated wedges into contact with the sides of the hole.
Some of the existing systems, particularly those used in the coal mines, have the ability to be tensioned during or at the completion of fixing. This is achieved by threading the end of the bolt, and tightening a nut against a plate to apply a compressive load to the roof rock, at the same time, tensioning the bolt.
Most of the bolts in current use have some pattern or shape that increases their adhesion to the sides of the hole. The patterns are either knurling (similar to that used for reinforcing bar), "V" threading or distortion of the final shape (wiggle tail bolts etc.).
The technique of installation of the existing bolts is described in point form as:
This cycle is repeated every 0.5 to 1.5 meters of tunnel advance in coal mines, and every 3 to 200.0 meters of tunnel advance in metalliferous mines.
The main drawback of the existing systems is the number of steps involved and the time taken to install the bolt.
DISCLOSURE OF INVENTION
In one broad form the present invention is a drillable bolt adapted to be drilled into an earth, resin or the like material by a drive means, said bolt comprising at least one externally threaded hollow tube having at least one cutting tip at one free end and the drive means at or near the other end and wherein in use at least one lubricating fluid is urged between a core which is the result of drilling and the inner surface of the hollow tube past said cutting tip at or near the external surface of said hollow tube and once said bolt has been drilled into a desired position a liquid cement is urged between said core and the inner surface of the hollow tube past said cutting tip and around the external surface of said hollow tube to secure said drillable bolt in the earth, rock or like material.
In another form the present invention comprises a drillable bolt adapted to be drilled into an earth, rock or the like material by a drive means, said bolt comprising an externally threaded hollow tube having at least one cutting tip at one end and wherein, in use, a lubricating fluid is urged along the inner surface of the hollow tube to the cutting tip end to assist the cutting action and grout is then urged along the inner surface of the hollow tube past the cutting tip and around the external surface of said hollow tube to secure said hollow tube in the earth, rock or the like material.
In a further form the present invention is a method of installing a hollow drillable ground support bolt into an earth, rock or the
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patent: 5259702 (1993-11-01), Simpson
Standish Peter N.
Wright Leonard
Litman Richard C.
Reese Randolph A.
Ricci John
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