Expansion bolt and mine roof reinforcement
AssigneeThe Curators of the University of Missouri
InventorsRobert L. Davis, Harold D. Keith
Life of this patent
Estimating the term…
Abstract
An expansion bolt, adapted to be anchored in a hole, having a hollow shank portion adapted to hold a pressurizing fluid and to expand girthwise on pressurization of the fluid, and further having a threaded portion adapted on insertion of the shank portion in the hole to extend out of the hole and to have a nut threaded thereon, whereby, following insertion of the shank portion of the bolt, in an unexpanded condition, in the hole, the shank portion may be expanded by pressurization of fluid therein for anchoring it in the hole and the nut threaded up on the threaded portion of the bolt.
Claims32
An expansion bolt adapted for insertion in an initial unexpanded condition in a circular hole drilled in a body in which the bolt is to be anchored, and adapted to be expanded girthwise after being inserted in the hole to anchor it in the hole, said bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end as inserted in the hole and having a head at its other end constituting its outer end, said head being exteriorly threaded for reception of a nut and extending out of the hole when the bolt is anchored in the hole, said tubular member being adapted to receive a fluid under pressure, said tubular member being of closed cross section and of generally circular overall outline smaller than the circular hole for insertion of the bolt therein and being of fluted formation with a portion within said outline such as to enable girthwise expansion thereof under pressure of fluid therein for pressure engagement of a major portion thereof having a generally cylindrical outer surface with the body within the hole, and said head being constructed for delivery of fluid under pressure into said tubular member whereby, following insertion of the tubular member in a hole, fluid under pressure may be delivered into the tubular member to cause it to expand girthwise into pressure engagement of said generally cylindrical outer surface with the body within the hole for anchoring it in the hole.
An expansion bolt adapted for insertion in an initial unexpanded condition in a circular hole drilled in a body in which the bolt is to be anchored, and adapted to be expanded girthwise after being inserted in the hole to anchor it in the hole, said bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end as inserted in the hole and having a head at its other end constituting its outer end, said tubular member being adapted to receive a fluid under pressure, said tubular member being of closed cross section and of generally circular overall outline smaller than the circular hole for insertion of the bolt therein and being of fluted formation with a portion within said outline, a major portion thereof having a generally cylindrical outer surface, said tubular formation being such as to enable girthwise expansion thereof under pressure of fluid therein, said head having a passage therethrough to said tubular member and valve means in said passage in the head adapted to open for delivery of fluid under pressure through said passage into said tubular member for expanding it girthwise into pressure engagement of said generally cylindrical outer surface with the body within the hole after the bolt has been inserted in a hole and to close for maintaining fluid under pressure in said expanded tubular member for anchoring it in the hole.
The method of reinforcing the roof of a mine comprising:
- providing an expansion bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end and having a head at its other end constituting its outer end, said tubular member being adapted to hold a fluid under pressure, said tubular member being of closed cross section and of generally circular overall outline smaller than the circular hole for insertion of the bolt therein and being of fluted formation with a portion within said outline, a major portion thereof having a generally cylindrical outer surface, said tubular formation being such as to enable girthwise expansion thereof under pressure of fluid therein, said head having valve means therein adapted to open for delivery of fluid under pressure into said tubular member for expanding it girthwise into pressure engagement of said generally cylindrical surface with the body within the hole and to close for maintaining pressure in said tubular member,
- providing a circular hole in the roof of such size as to permit insertion of the shank portion of the bolt therein with the head extending down out of the hole,
- connecting a source of fluid under pressure to the passage in the head and delivering fluid under pressure through the passage, the valve being open, into the tubular member for expanding it girthwise into pressure engagement of said generally cylindrical outer surface with the roof within the hole for anchoring it in the hole,
- and effecting closing of the valve means to maintain pressure in the expanded tubular member.
The method of reinforcing the roof of a mine comprising:
- providing an expansion bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end and having a head at its other end constituting its outer end, said tubular member, in its unexpanded condition, having a closed cross-sectional shape comprising a first and major portion generally in the shape of an arc of a circle having a generally cylindrical outer surface and a second portion bent inwardly to a position within the confines of the circle, said tubular member being adapted to expand girthwise under pressure of fluid therein, said head having a passage for delivery of fluid under pressure to said tubular member for expanding it,
- providing a circular hole in the roof of such size as to permit insertion of the shank portion of the bolt therein with the head extending down out of the hole, and
- connecting a source of fluid under pressure to the passage in the head and delivering fluid under pressure through the passage into the tubular member for expanding it girthwise into pressure engagement of said generally cylindrical outer surface with the roof within the hole for anchoring it in the hole.
An expansion bolt adapted for insertion in an initial unexpanded condition in a circular hole drilled in a body in which the bolt is to be anchored, and adapted to be expanded girthwise by fluid under pressure after being inserted in the hole to anchor it in the hole, said bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end as inserted in the hole and having means at its other end constituting its outer end with a passage therethrough to the interior of said shank portion for delivery of fluid under pressure into said shank portion for expanding it girthwise, said tubular metal member in its initial unexpanded condition having a closed cross-sectional shape a major portion of which is of continuous generally circular form having a generally cylindrical outer surface and another portion of which, continuous with said major portion, is bent into the form of a loop extending inwardly with respect to said major portion, said loop permitting girthwise expansion of said tubular metal member into pressure engagement of said generally cylindrical outer surface with the surface of the body within the hole on delivery of fluid under pressure through said passage into said tubular metal member.
The method of reinforcing the roof of a mine comprising:
- providing an expansion bolt having an elongate hollow shank portion constituted by a relatively thin-walled tubular metal member closed at one end constituting its inner end and having means at its other end constituting its outer end with a passage therethrough to the interior of said shank portion for delivery of fluid under pressure into said shank portion for expanding it girthwise, said tubular metal member in its initial unexpanded condition having a closed cross-sectional shape a major portion of which is of continuous generally circular form having a generally cylindrical outer surface and another portion of which, continuous with said major portion, is bent into the form of a loop extending inwardly with respect to said major portion, said loop permitting girthwise expansion of said tubular metal member into pressure engagement of said generally cylindrical outer surface with the surface of the body within the hole on delivery of fluid under pressure through said passage into said tubular metal member;
- providing a circular hole in the roof of such size as to permit insertion of the shank portion of the bolt therein inner end first with said passage means at the lower end of the hole, and
- connecting a source of fluid under pressure to said passage and delivering fluid under pressure through the passage into the tubular member for expanding it girthwise into pressure engagement of said generally cylindrical outer surface with the roof within the hole for anchoring it in the hole.
In a method of rock bolting wherein an elongated tube-formed bolt is first inserted into a circular borehole and then expanded against the borehole,
- the improvement comprising:
- inserting a bolt freely into the borehole which, before being expanded, in its tubular cross-section has a peripheral length in a direction transverse to the axial direction of the bolt that exceeds the circumference of the borehole, the bolt having a closed cross-section with a major portion thereof having a generally cylindrical outer surface and with at least a part of its closed crosssection initially inwardly collapsed toward the axis of the bolt continuously along a substantial length of the bolt so that in its initially collapsed state the bolt is slimmer than the borehole and so that it can be freely inserted into the borehole;
- then expanding said bolt by applying an expansion medium internally of the bolt such that said generally cylindrical outer surface is moved into contact with the borehole to frictionally clamp against the walls of the borehole.
A method of reinforcing rock comprising:
- providing a bolt that comprises an expansible elongated tube which has a deep continuous longitudinal depression which extends inwardly of the bolt toward the axis of the bolt, the tube having a closed cross section including said depression and a major portion having a generally cylindrical outer surface, and being closed at one end thereof;
- drilling a circular hole in the rock of a diameter large enough to permit the unexpanded bolt to be freely inserted in the borehole;
- inserting the bolt in the borehole with said closed end first;
- coupling the other end of said tube to an external source of hydraulic pressure fluid;
- plastically deforming said tube by applying said hydraulic pressure fluid to the interior of said tube to expand said tube against the borehole over substantially the entire length of the bolt by expanding said depression outwardly substantially without stretching the material of the tube so as to cause permanent gripping action of said generally cylindrical outer surface against the inner surface of the borehole.
A method of reinforcing rock comprising:
- plastically deforming a transverse cross-section of a circular tube so that its transverse size is reduced, at least a continuous portion of said tube in its longitudinal direction having said plastically deformed cross section to form a plastically deformed portion of the tube, said cross section being a closed cross section and said plastically deformed portion of the tube including a major portion having a generally cylindrical outer surface;
- drilling a circular hole in the rock, the hole having a diameter larger than the reduced transverse size of the plastically deformed tube so that the deformed tube can be freely inserted into the borehole;
- inserting the deformed tube in the borehole;
- and
- then further plastically deforming the deformed tube in the borehole substantially without stretching the material of the tube by applying an expansion medium to the interior of the tube so that it expands the deformed portion of the tube in the transverse direction of the tube and thereby clamps said generally cylindrical outer surface frictionally against the inner surface of the borehole.
A method of rock bolting comprising:
- providing a bolt that comprises a radially expansible elongated tube which, before being used, has a deep closed continuous longitudinal depression extending inwardly of
- the tube toward the axis of the tube, the tube being closed at one end thereof, the tube having a closed continuous cross-sectional portion at least over the longitudinally depressed portion thereof, the depression extending inwardly from a major portion of the tube having a generally cylindrical outer surface;
- drilling a circular hole in the rock of a diameter that is larger than the largest transverse dimension of the bolt before being used but smaller than the largest transverse dimension of the bolt if said longitudinal depression is fully expanded, so that the longitudinal depression cannot be fully expanded when the bolt is in the borehole;
- inserting the bolt in the borehole with said closed bottom end first;
- coupling the other end of said tube to an external source of hydraulic high pressure fluid to fill the interior of the tube with the high pressure fluid under substantially static conditions so that the fluid is plastically deformed under the influence of said high pressure fluid to expand said depression outwardly of the tube so as to cause permanent gripping action of said generally cylindrical outer surface against the inside surface of the borehole over substantially the entire length of the tube.
Dependencies are inferred from the claim text.