Abstract: It discloses a sustained release grouting material, a preparation method and an application thereof; the sustained release grouting material comprises a water swelling core and a water-soluble sustained release coating, the water swelling core is composed of bentonite, SAP and xanthan gum, which is granulated by disc granulator relying on the cohesiveness of xanthan gum; the water-soluble sustained-release coating is prepared by mixing water-soluble starch, polyvinyl alcohol, poloxamer, lubricant and plasticizer with deionized water to obtain a film-forming solution, and the film-forming solution is coated on a coating machine; the invention uses a coating machine to coat a layer of slow-release coating on the surface of the water-absorbing expansion core, and adjusts the coating thickness by controlling the mass ratio of the coating film-forming liquid to the water-absorbing expansion core particles, so as to realize the controllable water absorption onset time of the expansion core.

Abstract: An underground gasifier pre-control structure includes a flame retardant injection system. The flame retardant injection system includes a flame retardant injection shaft pipe channel drilled from ground to a coal seam and a flame retardant injection channel located in the coal seam. The flame retardant injection channel includes a first flame retardant injection channel and a second flame retardant injection channel at both sides of each gasifier and a third flame retardant injection channel located in a horizontal direction of an adjacent gasifier. The first flame retardant injection channel includes a horizontal section along a strike of the coal seam and a bypass section offset toward the gasifier. The flame retardant injection system forms a wet coal wall in the coal seam to achieve pre-control for the gasifier. The pre-control structure wets the coal masses at both sides of the gasifier and the gasifier does not spread toward both sides.

Abstract: A method and a system for determining a supporting structure by combining a stress environment and an underground surrounding rock structure are provided in the disclosure, which relates to the technical field of stability analysis of coal-mine rock mass. The method includes: defining a stress peak position and an in-situ stress position by determining the stress environment; identifying the underground surrounding rock structure, identifying lithology and constructing a three-dimensional model of a rock stratum to analyze damage degree of the rock stratum; pretreating, namely normalizing, the damage degree of the rock stratum at two sides and comparing the damage degree of the rock stratum at a roof and the floor; and identifying the supporting structure and determining supporting effectiveness and a supporting length. The method of the disclosure is different from related art, and ensures that the supporting structure meets mechanical foundation and practical engineering requirements as a whole.

Abstract: It discloses a sustained release grouting material, a preparation method and an application thereof; the sustained release grouting material comprises a water swelling core and a water-soluble sustained release coating, the water swelling core is composed of bentonite, SAP and xanthan gum, which is granulated by disc granulator relying on the cohesiveness of xanthan gum; the water-soluble sustained-release coating is prepared by mixing water-soluble starch, polyvinyl alcohol, poloxamer, lubricant and plasticizer with deionized water to obtain a film-forming solution, and the film-forming solution is coated on a coating machine; the invention uses a coating machine to coat a layer of slow-release coating on the surface of the water-absorbing expansion core, and adjusts the coating thickness by controlling the mass ratio of the coating film-forming liquid to the water-absorbing expansion core particles, so as to realize the controllable water absorption onset time of the expansion core.

Abstract: A method is to excavate main roadways in the upper and lower parts separately and an inclined intake roadway in the central part of the mine and pre-excavate an inclined seam roadway as the first mining face at the boundary on one side of the mine. Staring from the mine boundary, the retreating mining shall be carried out on the first mining face strip by strip with belt conveyors arranged in the upper main roadway and assistant conveying devices in the lower main roadway and inclined intake roadway; the open-off cut of the first mining face shall be built on the underside of the upper main roadway at the boundary of the mine to carry out the downward inclined mining on the strike and along the inclination.

Abstract: A method is to excavate main roadways in the upper and lower parts separately and an inclined intake roadway in the central part of the mine and pre-excavate an inclined seam roadway as the first mining face at the boundary on one side of the mine. Staring from the mine boundary, the retreating mining shall be carried out on the first mining face strip by strip with belt conveyors arranged in the upper main roadway and assistant conveying devices in the lower main roadway and inclined intake roadway; the open-off cut of the first mining face shall be built on the underside of the upper main roadway at the boundary of the mine to carry out the downward inclined mining on the strike and along the inclination.

Abstract: An underground gasifier pre-control structure includes a flame retardant injection system. The flame retardant injection system includes a flame retardant injection shaft pipe channel drilled from ground to a coal seam and a flame retardant injection channel located in the coal seam. The flame retardant injection channel includes a first flame retardant injection channel and a second flame retardant injection channel at both sides of each gasifier and a third flame retardant injection channel located in a horizontal direction of an adjacent gasifier. The first flame retardant injection channel includes a horizontal section along a strike of the coal seam and a bypass section offset toward the gasifier. The flame retardant injection system forms a wet coal wall in the coal seam to achieve pre-control for the gasifier. The pre-control structure wets the coal masses at both sides of the gasifier and the gasifier does not spread toward both sides.

Abstract: Provided are a grouting anchor bolt and a grouting anchor cable for supporting of large deformation and constant resistance and a quantitative roadway supporting method, wherein an anchor bolt comprises a casing, a hollow rod body, an anchor cylinder, a tray, a fastening nut and a clamping pin, a front end of the casing is sealed and a rear end of the casing is opened, a middle position of the casing is provided with a plurality of grouting holes, an inner diameter of the casing from the middle position of the casing to the rear end becomes small gradually, a side surface of a front end of the hollow rod body is sleeved with an anchor cylinder, the anchor cylinder is inserted into the casing and movably connected with the casing, the anchor cylinder is connected with the casing through the clamping pin, a rear end of the hollow rod body is sequentially assembled and connected with the tray and the fastening nut.

Abstract: Provided are a grouting anchor bolt and a grouting anchor cable for supporting of large deformation and constant resistance and a quantitative roadway supporting method, wherein an anchor bolt comprises a casing, a hollow rod body, an anchor cylinder, a tray, a fastening nut and a clamping pin, a front end of the casing is sealed and a rear end of the casing is opened, a middle position of the casing is provided with a plurality of grouting holes, an inner diameter of the casing from the middle position of the casing to the rear end becomes small gradually, a side surface of a front end of the hollow rod body is sleeved with an anchor cylinder, the anchor cylinder is inserted into the casing and movably connected with the casing, the anchor cylinder is connected with the casing through the clamping pin, a rear end of the hollow rod body is sequentially assembled and connected with the tray and the fastening nut.

Abstract: A test device and a test method of fractured rock mass collapse and blockfall and fracture water inrush includes a fractured rock mass preparation device, a water source loading device, a surrounding rock pressurization device and a slide rail, wherein the fractured rock mass preparation device is fixed at one end of the slide rail, and the water source loading device is fixed on the other side of the slide rail. An opening is formed in the rock mass water storage structure, and the size of the opening is adapted to the size of the fractured rock mass; the surrounding rock pressurization device includes one bracket and a pressurization structure arranged below the bracket, and a space for accommodating the fractured rock mass is reserved below the pressurization structure; and the bottom support and the bracket are both movably installed on the slide rail.

Abstract: The present invention discloses a four-double working method for danger assessment and prediction of water inrush in a roof aquifer of a coal seam, and belongs to the coal mining field. The method includes: calculating a water abundance index and/or a danger index of water inrush of a roof of a to-be-mined coal seam according to position classification of the roof of the to-be-mined coal seam; and obtaining a water inrush assessment result of the roof of the to-be-mined coal seam according to the water abundance index and/or the danger index of water inrush of the roof of the to-be-mined coal seam and excavation area position information of the roof of the to-be-mined coal seam. The present invention resolves the problem that current water abundance assessment and danger assessment and prediction of water inrush are complex and inaccurate.

Abstract: A test device and a test method of fractured rock mass collapse and blockfall and fracture water inrush includes a fractured rock mass preparation device, a water source loading device, a surrounding rock pressurization device and a slide rail, wherein the fractured rock mass preparation device is fixed at one end of the slide rail, and the water source loading device is fixed on the other side of the slide rail. An opening is formed in the rock mass water storage structure, and the size of the opening is adapted to the size of the fractured rock mass; the surrounding rock pressurization device includes one bracket and a pressurization structure arranged below the bracket, and a space for accommodating the fractured rock mass is reserved below the pressurization structure; and the bottom support and the bracket are both movably installed on the slide rail.