Abstract: The present invention discloses a self-anchored opposite-pulling anti-impact anchor cable for sectional coal pillars and a using method thereof. The anchor cable includes a steel strand (100), with an energy-absorbing and yielding terminal (200) and a stressed expansion-cracking terminal (300) respectively fixed to two ends of the steel strand, a bushing (400) sleeved outside the steel strand, a first lock (610) provided at one end of the steel strand and a second lock (620) provided at the other end of the steel strand; the stressed expansion-cracking terminal includes a self-anchored bushing (420) with a plurality of pre-splitting lines (440) arranged in the wall of the self-anchored bushing. Under stress, the wall of the self-anchored bushing cracks along the pre-splitting lines and bends and expands, so that it abuts against and is self-anchored to the edge of a sectional coal pillar at the outer side.

Abstract: A tensile-testing apparatus (10) comprises a platen (40) for situating a tendon-type support system in manner mimicking its expected installation condition. A force-imposing device (20) imposes installation-expected forces and sensors (61, 71) sense displacement in the force-imposing direction. A station (80) collects force and displacement data and a station (90) outputs the collected data in format allowing system analysis.

Abstract: A ground stabilizing device (10) comprises a securing arrangement (16) and a load spreading arrangement (18) on the securing arrangement. The securing arrangement defines a through passage (40) for an elongate article (12). The securing arrangement comprises a guide member (54) extending towards the passage, and a clamping assembly (38). The clamping assembly is movable along the guide member towards the passage to clamp the elongate article in the passage and secure the elongate article to the ground stabilizing device.

Abstract: A wedge anchor bolt having a screw member, a wedge member, and a cage member. The bolt is anchored into a drilled hole by wedging the wedge member in the end of the cage member by turning the screw member, with the result being that the wedge member becomes stuck in the cage member. For ejecting the wedge member from the cavity the screw member includes at least one of (1) one or more depressed portions, and (2) one or more projecting portions, defining a step, and the cage member includes one or more corresponding step-engaging portions for making an interference contact with the step, so that further withdrawal of the threads ceases to withdraw the threads relative to the cage member while continuing to withdraw the threads relative to the wedge member, thereby forcing the wedge member distally relative to the cavity.

Abstract: A wedge anchor bolt having a screw member, a wedge member, and a cage member. The bolt is anchored into a drilled hole by wedging the wedge member in the end of the cage member by turning the screw member, with the result being that the wedge member becomes stuck in the cage member. For ejecting the wedge member from the cavity the screw member includes at least one of (1) one or more depressed portions, and (2) one or more projecting portions, defining a step, and the cage member includes one or more corresponding step-engaging portions for making an interference contact with the step, so that further withdrawal of the threads ceases to withdraw the threads relative to the cage member while continuing to withdraw the threads relative to the wedge member, thereby forcing the wedge member distally relative to the cavity.

Abstract: An anchor comprises an anchor bolt having a shaft and a bolt head, a spreading sleeve having spreading parts provided at a tip portion of a tubular body capable of being fitted on a tip portion of the shaft and a cone nut provided at its inner side a screw through hole to threadedly engage with the shaft. The shaft of the anchor bolt is composed of a thick shaft part connected to the bolt head, and a thin shaft part provided to be closer to the tip portion of the shaft. The thick shaft part is provided with a rupture portion reduced in diameter. The rupture portion is provided at a position spaced by a predetermined length from the step between the thick shaft part and the thin shaft part and ruptures if torque of a predetermined value acts on the bolt head.

Abstract: A tension dispersion type complex anchor device includes an internal fixing body having a tension member which is placed through a free length section to apply a tension force and a fixing block to which a wedge assembly for grasping a distal end of the tension member is mounted; a connection medium unit for mounting the internal fixing body to one end thereof; a grip sleeve coupled to the other end of the connection medium unit; and a permanent anchor fixed by being fitted into the grip sleeve to provide an allowable anchoring force through a bonded length section.

Abstract: A mine roof bolt includes an elongated rod and a polymer coating layer. The elongated rod has a first end and a second end with a protruding portion extending radially outward from the elongated rod. The polymer coating layer covers at least a portion of the elongated rod between the first and second ends. The elongated rod is movable relative to the polymer coating layer in an axial direction. The elongated rod has a first position where the elongated rod has a predetermined axial position relative to the polymer coating layer and a second position where the elongated rod has a displaced axial position relative to the first position.

Abstract: A friction bolt, for frictionally engaging the internal surface of a bore drilled into a rock face. The friction bolt comprises an elongate, generally circular tube which is expandable radially. The tube has a leading end and a trailing end. An expander mechanism is disposed within the tube for applying a load tending to expand at least a section of the tube radially. An elongate tendon is disposed longitudinally within the tube and in connection at or towards one end of the tendon with the expander mechanism and in connection at or towards an opposite end of the tendon with an anchor arrangement. The tendon is actuatable to expand the expander mechanism and to remain connected between the expander mechanism and the anchor arrangement while the expander mechanism is expanded.

Abstract: A rock bolt comprising a shaft having first and second ends, and an anchoring device operative to retain the bolt when located in a drilled hole and comprising a mandrel mounted to, or integrally formed with, the shaft and at least one expansion element overlaying the mandrel, at least one of the mandrel or the at least one expansion element being a movable member and being able to rotate relative to, and move axially along, the shaft, the at least one expansion element being arranged to be displaced radially outwardly on a predetermined relative movement between the mandrel and the at least one expansion element, wherein when disposed on a first portion of the shaft, rotation of the movable member relative to the shaft causes axial movement of that member along the shaft, and when disposed on a second portion of the shaft, the movable member is able to rotate on the shaft without being biased to move axially along the shaft.

Abstract: A rock bolt component includes an elongate tubular section with an internal bore. A fixing member has an elongate body that includes a securing portion positionable in the internal bore of the tubular section and a coupling formation which projects from an opposite end of the fixing member. The fixing member is securable by deformation of an end of the tubular section, once the securing portion of the fixing member has been inserted into the end of the tubular section.

Abstract: A cable bolt comprising a tension member having a first end and a second end. A rotatable collar is positioned on the tension member and is rotatable relative to the tension member. An elongate sheath, having a first end and a second end, is disposed over at least a portion of the tension member and secured to the rotatable collar. A method of securing an anchor in a structure is also disclosed.

Abstract: A mine roof support includes a substantially dome-shaped plate including a curved portion having a first side and a second side. The mine roof support includes a drive end such as a barrel and wedge assembly, a nut or a forged head. The first side of the plate is adapted to mate with a recess defined in a mine roof. A top portion of the drive head may be contoured to substantially match the contour of the second side of the plate. A drill bit tool used to create the recess includes a first drill bit situated at one end of the drill bit tool and a second drill bit situated near an opposite end of the drill bit tool, wherein the drill bit tool is adapted to drill a bore hole and the recess. A method for supporting the mine roof utilizes the mine roof support.

Abstract: An expansion shell assembly for mine roof bolts includes an expansion member threaded onto an associated mine roof bolt. A support device is annularly disposed around the associated roof bolt. An expansion shell is annularly disposed around the associated roof bolt between the expansion member and the support device. The expansion shell has a base ring for engaging the support device and fingers for engaging a peripheral edge of the tapered plug. The engagement between the base ring and the support device permits axial traverse movement of the support device relative to the expansion shell for tensioning the roof bolt.

Abstract: A mine roof support assembly for anchoring in a bore hole by means of a resin, cementitious grout which includes an elongated reinforcing tendon which extends from a proximal end portion to a distal end portion. A slip sheath formed from a heat shrunk plastic, is secured by heat shrinkage radially about the tendon. The sheath is mechanically coupled to the tendon so as to allow the desired axial sliding of the tendon relative to the sheath on the application of predetermined forces which sufficient to effect any desired yielding movement of the tendon in the bore hole. An anti-bonding agent or coating and/or anticorrosive may be interposed between the sheath and the tendon, whereby the sheath substantially encapsulates and limits the admixing of the interposed anti-bonding agent/anti-corrosive coating with the resin.

Abstract: In an anchoring device, a drill head and expansion element(s) are configured to cooperatively interlock with each other to provide for directed movements of the drill head relative to a longitudinal axis of the shaft. Co-operating contact surfaces between the drill head and the expansion element(s) are configured such that relative longitudinal movement of the drill head with respect to the expansion element(s) displace(s) the expansion element(s) outwardly so the expansion element(s) can provide frictional contact with a borehole once inserted therein.

Abstract: A drilling tool incorporating first and second ends, a shaft extending between the ends. The first end has a drill bit to penetrate rock. The drill bit and the shaft have complementary threads. The drill bit and the shaft comprise a relative rotation stop means that ensures that the drill bit remains loose during drilling in a first direction. The invention further relates to a self drilling rock bolt, a drill bit, drill shaft and shaft coupling, an anchoring device, and an end coupling per se.

Abstract: A bolt anchor is comprised of a camming element and sleeve. The camming element is generally cylindrical, but with a larger midsection and reduced diameters at each end. The camming element includes a threaded bore along its axis and at least one stop near one end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The stop maintains the assembly of the camming element and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole. Reduced material thickness associated with the leaves produces hinges which allow the leaves to be more easily deformed outwardly. Inserting a bolt and anchor assembly into the hole and turning the bolt pulls the camming element into the sleeve and creates a wedging effect in the hole.

Abstract: A tensionable cable bolt including a length of multi-strand cable and an anchoring portion comprised of a shaft received on the cable and attached to the cable at a crimp portion comprising at least one primary crimp with at least one secondary crimp disposed within the primary crimp. The cable may include a mixing portion and the anchor portion may include an expansion anchor threaded onto the shaft. A method of manufacturing the tensionable cable bolt includes providing a length of multi-strand cable; providing an anchoring portion including a shaft; extending the cable through the shaft; and crimping the shaft to the cable to form at least one primary crimp with at least one secondary crimp disposed within the primary crimp. The method may further include threading an expansion anchor onto the shaft and/or providing a resin mixing portion along the cable.

Abstract: A rock anchor (10) which includes a cable (12) with a hollow core, an expansion mechanism (20) at one end of the cable, a tube (14), which acts on a load washer (16), in which part of the cable is located, and a wedge (18) which locks the cable to the tube.

Abstract: A bolt anchor is comprised of a body and sleeve. The body is generally wedge shaped with a threaded bore along its axis and at least one stop near its smaller end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The at least one stop maintains the assembly of the body and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole using the bolt anchor. Reduced material thickness associated with the leaves on the sleeve produces hinges which allow the leaves to be more easily deformed outwardly to engage the sides of a hole. Inserting a bolt and bolt anchor assembly into the hole and then turning the bolt pulls the body into the sleeve and creates a wedging effect in the hole.

Abstract: A rock bolt comprising a shaft having first and second ends, and an anchoring device operative to retain the bolt when located in a drilled hole and comprising a mandrel mounted to, or integrally formed with, the shaft and at least one expansion element overlaying the mandrel, at least one of the mandrel or the at least one expansion element being a movable member and being able to rotate relative to, and move axially along, the shaft, the at least one expansion element being arranged to be displaced radially outwardly on a predetermined relative movement between the mandrel and the at least one expansion element, wherein when disposed on a first portion of the shaft, rotation of the movable member relative to the shaft causes axial movement of that member along the shaft, and when disposed on a second portion of the shaft, the movable member is able to rotate on the shaft without being biased to move axially along the shaft.

Abstract: The invention relates to a device (D) for locking/unlocking to the ground (S) of a connecting plate (100) to the ground or to the rim of a basin of a roof element, the plate (100) being on the one hand connected to the rim of the roof element and on the other hand connected to the ground (S) or to the basin rim, the plate (100) being pierced with an orifice (121) coming opposite a hole (200) made in the ground, the locking/unlocking device interacting with the hole (200) made in the ground and resting on the plate (100) for the purpose of attaching the latter. This device is noteworthy in that it comprises an expandable bush (300) changing from a volume called a rest volume allowing it to be inserted into the hole (200) made in the ground to a volume called the expanded volume ensuring its adhesion to the walls (210) of the said hole (200). Applications: attaching swimming pool shelters.

Abstract: A tension dispersion type complex anchor device includes an internal fixing body having a tension member which is placed through a free length section to apply a tension force and a fixing block to which a wedge assembly for grasping a distal end of the tension member is mounted; a connection medium unit for mounting the internal fixing body to one end thereof; a grip sleeve coupled to the other end of the connection medium unit; and a permanent anchor fixed by being fitted into the grip sleeve to provide an allowable anchoring force through a bonded length section.

Abstract: An anchor 1 for consolidating non-cohesive rock layers or for connecting them to solid rock 2 primarily has the necessary components for realising a stressed or expansion anchor. Furthermore, when a conventional domed plate 10 is used, which reliably transmits the necessary stress forces, it is possible additionally to bond the anchor bar 4 in the drill hole 3 after stressing. To this end, the anchor bar 4 is either constructed with a connecting tube 22 with distributor head 24 or the sheathing tube 11 comprises a top tube 50, these both fulfilling the task of conveying the grout bonding material 12 reliably from the drill hole mouth end of the anchor bar 4 to the rock end 5A and then diverting it there and returning it to the drill hole mouth, so ensuring complete fixing and sheathing of the anchor bar 4 in the drill hole 3.

Abstract: The present invention relates to rock bolts which may be used in mining applications. The rock bolt of this invention includes a mechanical anchoring arrangement to facilitate retaining the rock bolt in a borehole, and also a drill bit to enable self drilling of the rock bolt. Rotation of the rock bolt about an axis of the rock bolt in a first direction causes the drill bit to drill into rock and to create a borehole to receive the rock bolt. Subsequently, rotation in the opposite direction actuates a mechanical anchoring arrangement to anchor rock bolt.

Abstract: The present invention relates to a rock bolt comprising first and second ends, a shaft extending between the ends, and an anchoring device extending along a first part of the shaft adjacent the first end. The anchoring device comprises a mandrel, and at least one expansion element overlaying the mandrel. The expansion element is displaced radially outwardly on a predetermined relative movement between the mandrel and the expansion element. The expansion element is joined to a connector to form an anchor assembly. The anchor assembly is keyed to the mandrel. The anchor assembly comprises relative rotation actuator means active during rotation of the anchoring device. The invention further relates to an anchoring device per se.

Abstract: A mine roof support includes a plate having a raised portion with an opening, and a mine and roof bolt, e.g. a barrel having a drive end and an opposite second end, and wedge assembly. The plate mates with a recess in a mine roof. In one embodiment, the second end of the barrel extends through the opening in the dome into a bore hole in the mine roof. In another embodiment, a second end of the mine bolt is contoured to match and fill the inner contour of the dome. A drill bit tool used to shape the recess includes a first bit, a second bit, and a third bit between the first and second bits to drill a bore hole, enlarge the end of the bore hole to receive the second end of the mine bolt, and to drill the recess.

Abstract: A bolt anchor is comprised of a camming element and sleeve. The camming element is generally cylindrical, but with a larger midsection and reduced diameters at each end. The camming element includes a threaded bore along its axis and at least one stop near one end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The stop maintains the assembly of the camming element and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole. Reduced material thickness associated with the leaves produces hinges which allow the leaves to be more easily deformed outwardly. Inserting a bolt and anchor assembly into the hole and turning the bolt pulls the camming element into the sleeve and creates a wedging effect in the hole.

Abstract: A bolt anchor is comprised of a body and sleeve. The body is generally wedge shaped with a threaded bore along its axis and at least one stop near its smaller end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The at least one stop maintains the assembly of the body and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole using the bolt anchor. Reduced material thickness associated with the leaves on the sleeve produces hinges which allow the leaves to be more easily deformed outwardly to engage the sides of a hole. Inserting a bolt and bolt anchor assembly into the hole and then turning the bolt pulls the body into the sleeve and creates a wedging effect in the hole.

Abstract: A cable bolt comprising a tension member having a first end and a second end. A rotatable collar is positioned on the tension member and is rotatable relative to the tension member. An elongate sheath, having a first end and a second end, is disposed over at least a portion of the tension member and secured to the rotatable collar. A method of securing an anchor in a structure is also disclosed.

Abstract: A bolt anchor is comprised of a body and sleeve. The body is generally wedge shaped with a threaded bore along its axis and at least one stop near its smaller end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The at least one stop maintains the assembly of the body and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole using the bolt anchor. Reduced material thickness associated with the leaves on the sleeve produces hinges which allow the leaves to be more easily deformed outwardly to engage the sides of a hole. Inserting a bolt and bolt anchor assembly into the hole and then turning the bolt pulls the body into the sleeve and creates a wedging effect in the hole.

Abstract: An adjustable yield rock bolt that comprises an elongated tensile support member that interacts with at least one gouging member and a receiving member capable of receiving the elongated tensile support member and hold the gouging member segment there between, wherein the elongated tensile support member extends beyond the receiving member a length that corresponds to a predetermined amount of yield before ultimate failure. The bolt has adjustability by allowing for controlled yield by gouging of the elongated tensile support member for any length of displacement.

Abstract: A self drilling rock bolt incorporating a shaft and an anchoring device. A first end of the bolt has a drill tip to penetrate rock and a second end is adapted to be connected to a drilling apparatus to allow rotation of, and thrust to, the bolt. A circulation passage is provided to allow fluid to be passed to the drill tip and in one form a central passage is formed in the shaft to form part of this circulation passage. The anchoring device is operative to retain the bolt when located in a drilled hole and comprises a mandrel having one or more inclined external surface mounted to, or integrally formed with, the shaft and at least one expansion element overlaying the mandrel. The expansion element(s) is displaced radially outwardly on a predetermined relative movement between the mandrel and the element.

Abstract: A method and device for drilling, particularly percussion drilling or rotary percussion drilling a hole in soil or rock material and fixing an anchoring in the hole. To this end, a drilled hole is made by a drill bit mounted on a drill rod. The drill rod, on the rear side facing away from the drilling surface of the drill bit, is surrounded at a distance from the drill bit by an anchoring element whose outside dimension exceeds, at least in part, the circumference of the drilled hole made by the drill bit.

Abstract: A bolt anchor is comprised of a body and sleeve. The body is generally wedge shaped with a threaded bore along its axis and at least one stop near its smaller end. The sleeve has a round collar with leaves extending from the collar parallel to the axis of the collar and each other. The at least one stop maintains the assembly of the body and sleeve. Prongs on the sleeve prevent the retraction or turning of the bolt anchor when a bolt is installed in a hole using the bolt anchor. Reduced material thickness associated with the leaves on the sleeve produces hinges which allow the leaves to be more easily deformed outwardly to engage the sides of a hole. Inserting a bolt and bolt anchor assembly into the hole and then turning the bolt pulls the body into the sleeve and creates a wedging effect in the hole.

Abstract: An expansion shell assembly for mine roof bolts includes an expansion member threaded onto an associated mine roof bolt. A support device is annularly disposed around the associated roof bolt. An expansion shell is annularly disposed around the associated roof bolt between the expansion member and the support device. The expansion shell has a base ring for engaging the support device and fingers for engaging a peripheral edge of the expansion member. The engagement between the base ring and the support device permits axial traverse movement of the support device relative to the expansion shell for tensioning the roof bolt.

Abstract: The present invention is directed to a device and assembly for the anchoring and tensioning of cable bolts used in earthen formations to stabilize the earthen structures to prevent or minimize the caving in or sluffing-off of the earthen structure. The new invention presents an integral wedge barrel and threaded sleeve which can be turned to facilitate both the mixture of cementing resins and the physical tensioning of an anchored cable.

Abstract: A mine roof support includes a plate having a raised portion with an opening, and a mine and roof bolt, e.g. a barrel having a drive end and an opposite second end, and wedge assembly. The plate mates with a recess in a mine roof. In one embodiment, the second end of the barrel extends through the opening in the dome into a bore hole in the mine roof. In another embodiment, a second end of the mine bolt is contoured to match and fill the inner contour of the dome. A drill bit tool used to shape the recess includes a first bit, a second bit, and a third bit between the first and second bits to drill a bore hole, enlarge the end of the bore hole to receive the second end of the mine bolt, and to drill the recess.

Abstract: A rock bolt and a method of installing a rock bolt in a borehole (3) of a rock formation. The rock bolt including an elongate shank (1) and an expansion assembly (2) located at the distal end of the shank. The expansion assembly being expandable to lock the rock bolt in a borehole upon relative forward rotation of the rock bolt. The rock bolt further including stop means (4) to lock the expansion assembly with respect to the rock bolt for conjoined rotation upon a reverse rotation of the rock bolt.

Abstract: A rock bolt anchor includes a top portion permanently fixed to a bottom portion. The top portion carries a package of resin. A spring-loaded mechanism pressurizes the package and forces the resin out when the package is lanced. The bottom portion main body carries a pair of opposed outer shells in a dovetail joint on opposed tapers. The annulus adjacent to the rock bolt anchor is sealed by top and bottom bulkheads. The bottom portion is threaded onto a rock bolt. A hollow and ported lance is threaded onto the exposed end of the rock bolt. The combination is inserted into a drilled hole and the rock bolt rotated. The lance rises and pierces the package releasing into the sealed annulus. Continued rotation of the rock bolt, forces the main body down and the outer shells up the tapers compressing them against the wall of the drilled hole.

Abstract: A self-drilling anchor screw includes a shaft member. A drill bit portion is located at a first end of the shaft member. A threaded shaft portion is located along at least part of the shaft member. A transition shaft portion is located between the threaded shaft portion and the drill bit portion. A nut has nut threads adapted to thread onto the threaded shaft portion of the shaft member. The nut is located on the threaded shaft portion. A sleeve is located about the shaft member. At least part of the sleeve is located adjacent to the transition portion, and is capable of sliding along the shaft member for engaging the transition portion. A nut stop portion is located at a second end of the shaft member. The nut stop portion is adapted to prevent the nut from being unscrewed from the threaded shaft portion at the second end of the shaft member.

Abstract: A resin bonded mine roof bolt having an elongated rod with a first end and a second end. A segmented resin compression layer covers a portion of the rod below the first end. When installed in a mine roof bore hole with curable resin, the resin compression layer mixes the resin and partially fills the bore hole to minimize the amount of resin needed to anchor the bolt. Individual segments of the layer are tapered to create a wedging force on resin with the bore hole.

Abstract: An improved mine roof bolt is disclosed. The mine roof bolt comprises a bolt portion having a threaded end, a slidable camming nut, a stop, and an expansion shell having a central threaded nut with wedge fingers extending from it. The camming nut is fitted into the expansion shell which is threaded onto the threaded section of the bolt. Turning the bolt while it is in a hole causes the expansion shell to move along the bolt and carry the camming nut to the stop located on the bolt, and this causes the wedge fingers to engage with the camming nut, spreading the wedge fingers into contact with the hole sides. As the turning of the bolt continues, the relative movement of the camming nut and wedge fingers increases the wedging effect within the hole until the bolt is anchored in the hole. While turning of the bolt may serve to mix a catalytic adhesive, the adhesive is not needed to activate the mechanical anchoring mechanism of the mine roof bolt.

Abstract: An adjustable yield rock bolt that comprises an elongated tensile support member that interacts with at least one gouging member and a receiving member capable of receiving the elongated tensile support member and hold the gouging member segment there between, wherein the elongated tensile support member extends beyond the receiving member a length that corresponds to a predetermined amount of yield before ultimate failure. The bolt has adjustability by allowing for controlled yield by gouging of the elongated tensile support member for any length of displacement.

Abstract: A rock stabilizer includes a metal tube with a tapered distal end and a flanged proximal end capable of being positioned within a bore in a mine wall. A slit runs substantially the entire length and indentations are formed in the outer surface along the length adjacent the slit so that grout pumped into the interior of the tube flows out of the slit and into the indentations. An expander wedge within the tube adjacent the distal end is actuatable from the proximal end after the stabilizer is installed in a bore. The wedge expands the distal end of the tube to firmly anchor the stabilizer in the bore. The expander wedge is formed of one wedge welded to the interior of the tube and a second wedge moveable toward the fixed wedge. The two wedges are temporarily maintained together in the interior of the tube before actuation.

Abstract: A resin bonded mine roof bolt having an elongated rod with a drive head at one end and an expansion anchor threaded onto the other end. A segmented resin compression layer covers a portion of the rod below the expansion anchor. When installed in a mine roof bore hole with curable resin, the resin compression layer mixes the resin and partially fills the bore hole to minimize the amount of resin needed to anchor the bolt. Individual segments of the layer are tapered to create a wedging force on resin with the bore hole. The expansion anchor is expandable upon initial hardening of the resin to tension the bolt.

Abstract: A roof bolt comprises a shaft for insertion in a hole drilled in a mine roof and a head whereby the bolt may be rotated, the head being offset with respect to the longitudinal axis of the shaft so that when the bolt is rotated by means of its head the shaft is caused to describe a circle of greater diameter than its own diameter, and where the offset is at least 0.08 inch and not more than 0.25 inch. Preferably the offset is from 0.10 to 0.16 inch. The invention includes a method for the production of roof bolts which comprise a shaft for insertion in a hole drilled in a mine roof and a head whereby the bolt may be rotated, the method being characterised by being controlled so that at least 90% of the bolts produced have their head central axis offset with respect to the longitudinal axis of the shaft by an amount of at least about 0.08 inch and not more than about 0.25 inch.

Abstract: The invention comprises a roof bolt and nut in screw threaded engagement, said bolt comprising a shaft for insertion in a hole drilled in a mine roof and a threaded portion engaged by the nut whereby the bolt may be rotated. The nut is offset with respect to the longitudinal axis of the shaft of the bolt so that when the bolt is rotated by means of the nut, the bolt is caused to describe a circle of greater diameter than its own diameter, the amount of said offset being from about 0.015 to about 0.50 inches. Preferably the offset is from about 0.02 to about 0.25 inches. The nut may be releasably locked in screw threaded engagement with the bolt so that the bolt can be rotated by means of the nut and above a selected torque the nut will break out.

Abstract: An improved mine roof bolt is disclosed. The mine roof bolt comprises a bolt portion having a camming nut rigidly fixed to it and a threaded end and an expansion shell having a central threaded nut with wedge fingers extending from it. The expansion shell is threaded onto the threaded section of the bolt. Turning the bolt while it is in a hole causes the expansion shell to move along the bolt and brings the wedge fingers into contact with the camming nut, spreading the wedge fingers into contact with the hole sides. As the turning of the bolt continues, the relative movement of the camming nut and wedge fingers increases the wedging effect within the hole until the bolt is anchored in the hole. While turning of the bolt may serve to mix a catalytic adhesive, the adhesive is not needed to activate the mechanical anchoring mechanism of the mine roof bolt.