An NPR steel material for rock bolt and a production method thereof are disclosed. The NPR steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, Mn: 15-20%, Si: 0.1%, Cu: 0.03%, Cr: 0.01%, Ni: 0.02%, S: 0.001%, P: 0.001%, and the rest being Fe and unavoidable impurity elements. The NPR steel material for rock bolt and the production method thereof effectively solve the problem that rock bolts in the prior art have low tensile strength and low effective elongation. The NPR steel material for rock bolt has a yield strength adjustable in the range of 500-1100 MPa, and an elongation adjustable in the range of 10-80%.

The present disclosure provides a system to optimally set an anchor and a bullet within a bore hole. The anchor is comprised of at least two cutters connected to and positioned below spreading lamellae of the anchor. The cutters are comprised of a wide edge and a narrow edge, the wide edge having a width that is wider than the circumference of the spreading lamellae to facilitate the setting of the anchor. A space is also initially provided between each of the cutters and the bullet to reduce friction of anchor on the bullet during expansion. During setting, the spreading lamellae of the anchor spread radially over the bullet to set the undercut anchor within the pre-drilled bore hole. In another embodiment, the anchor is comprised of at least two angular cutters having a taper of several degrees to facilitate cutting through the cementitious material of the bore hole.

A cuttable, sinkable mining bolt system for use in supporting the sidewall or rib in a coal mine. A bearing plate has a plurality of hollow cores defined transaxially therein and a central hole defined axially therethrough, the bearing plate made of modified recycled, rigid PVC compound. A fiberglass bolt is adapted to be inserted through the central hole of bearing plate.

Bolt is one-piece consisting of glass fiber reinforced plastic. Head component includes a square head and integral, beveled washer for self-centering in the bearing plate as rod component is driven into rib. Bearing plates are adapted to sink into a refuse stream. Hollow cores of bearing plate reduce the material and thus the weight and expense of the bearing plate while still allowing the bearing plates to sink. Optionally, rod components can be inserted transaxially through the hollow cores to increase the strength and coverage of the system.

It discloses a grouting bolt-cable composite beam and supporting method for advanced support of fractured surrounding rock in deep coal mines. The quadrate plates are fixed at both ends of the steel beam, the anchor cable holes are arranged in the center of the steel beam and the quadrate plates, and the diameter of anchor bolt holes should be larger than that of the grouting cables. There are four anchor bolt holes on each quadrate plate, and each anchor bolt hole corresponds to a anchor plate, the horizontal surface of the anchor plate is close to the quadrate plate, and the arc parts of the four anchor plates are all facing the center of the quadrate plate.

An elongated connecting element for anchoring members, which is provided with a first anchoring end portion designed to be inserted into an anchoring region and a second end portion which defines a head, which lies opposite the first anchoring end portion and is designed to interact with an element to be anchored. The elongated connecting element includes an external tubular element which accommodates an internal elongated body, the external tubular element defining, at the head, at least one feeding port for a synthetic anchoring mix and, at the first anchoring end portion, at least one exit opening for the synthetic anchoring mix. The synthetic anchoring mix is configured to set, penetrating at least partially into the anchoring region and creating a stable connection between the anchoring region and the elongated connecting element and between the respective portions of the external tubular element and of the internal elongated body.

A reaming and self-rotating anchor rod includes a rod body, a drill bit, a connecting member, a tray, and a nut. One end the connecting member is snap-fixed to the tail part of the rod body, the other end of the connecting member is connected to an anchor rod bolter. The rod body has an annular protrusion at its middle part to block powder so that the powder fills up the clearance between the rod body and the coal mass. The drill bit has female threads and can be screwed into the front part of the rod body, and the drill bit has baffle pawls and spiral grooves on its side surface.

An anchor bolt length determination method based on monitoring of a roof rock stratum horizontal extrusion force includes drilling a borehole in the middle of a roadway roof to determine a surrounding rock fracturing scope by a borehole television. The method includes selecting the number and locations of horizontal extrusion force measuring points according to the surrounding rock fracturing scope. The method includes monitoring and recording a change of the horizontal extrusion force over time in the borehole by a device for monitoring a roof rock stratum horizontal extrusion force. The method includes selecting a location with the largest horizontal extrusion force as a center of a anchoring segment of an anchor bolt to determine a distance between the anchoring center and the roof. The method includes calculating a total length of the anchor bolt.

An anchor bolt length determination method based on monitoring of a roof rock stratum horizontal extrusion force includes drilling a borehole in the middle of a roadway roof to determine a surrounding rock fracturing scope by a borehole television. The method includes selecting the number and locations of horizontal extrusion force measuring points according to the surrounding rock fracturing scope. The method includes monitoring and recording a change of the horizontal extrusion force over time in the borehole by a device for monitoring a roof rock stratum horizontal extrusion force. The method includes selecting a location with the largest horizontal extrusion force as a center of a anchoring segment of an anchor bolt to determine a distance between the anchoring center and the roof. The method includes calculating a total length of the anchor bolt.

An anchor rod includes a sleeve open at one end and having a blocking plate at the other end; a pressure relief pipe fixedly arranged on an inner wall of the sleeve; and a rod body. A guide hole is formed in a center of the blocking plate. A part of the rod body penetrates through the guide hole and extends into the sleeve. A gap is formed between the pressure relief pipe and the blocking plate. An overflow valve is connected to the pressure relief pipe. A piston in sliding seal fit with the sleeve and the pressure relief pipe is arranged at the rod body. A sealing ring in sliding seal fit with the rod body is arranged at the inner wall of the guide hole; and a sealing cavity between the blocking plate and the piston in the sleeve is filled with emulsion.

An asymmetric coordinated support device for gob side entry is provided. The device includes an inner support board, an outer roadway side support assembly, an outer roof support assembly, and a flexible reinforcement layer, wherein the inner support board is supported to an innermost side closest to a rock layer to be supported in an extending direction of the roadway, and wherein a side of the inner support board remote from the rock layer is provided with the outer roadway side support assembly extending along the roadway direction and the outer roof support assembly located on a roof of the outer roadway side support assembly.