Abstract: A method of recovering a room-and-pillar coal pillar by using external replacement supports. In the recovery of a room-and-pillar coal pillar, a cement material wall is formed by performing pouring around a coal pillar having a width to height ratio of less than 0.6, by means of a single-pillar sack arrangement technique, such that a coal pillar resource may be mined while a wall made from a cement filling material supports an overlying stratum. After mining is complete, a coal pillar goaf region is filled with the cement filling material, and after the cement filling material solidifies and is stable, the single pillar can be recovered.

Abstract: Provided is a base mechanism of a single prop capable of being unloaded at reduced pressure, including a base bottom plate and two wedge-shaped support blocks, where one of the wedge-shaped support blocks serves as a fixed wedge-shaped support block and is welded onto the base bottom plate, and the other of the wedge-shaped support blocks serves as a movable wedge-shaped support block and is connected to the fixed wedge-shaped support block by using a screw rod and a nut. The present invention can effectively unload the single prop at reduced pressure or remove the single prop in a contracted manner, is of a simple structure, is convenient to operate, has a good use effect, overcomes the technical problem that it is difficult to unload a single prop at reduced pressure in this technical feature, and is widely applicable in this technical field.

Abstract: The present invention discloses a mine exploitation method based on stoping, separation and filling control. The design process comprises: deploying a gangue-less coal mining system; choosing a suitable coal and gangue separation method according to a separation requirement; choosing a suitable filling method according to mine geology, production conditions and rock stratum control requirement; reversely calculating a filling rate according to gangue discharge requirement and control indexes by utilizing theoretical calculation, simulation and experiment; determining a filling process and a separation process according to the filling rate; and feeding back and adjusting the filling process and separation process parameters by monitoring filling and control effect indexes.

Abstract: A method of recovering a room-and-pillar coal pillar by using external replacement supports. In the recovery of a room-and-pillar coal pillar, a cement material wall is formed by performing pouring around a coal pillar having a width to height ratio of less than 0.6, by means of a single-pillar sack arrangement technique, such that a coal pillar resource may be mined while a wall made from a cement filling material supports an overlying stratum. After mining is complete, a coal pillar goaf region is filled with the cement filling material, and after the cement filling material solidifies and is stable, the single pillar can be recovered.

Abstract: Provided is a base mechanism of a single prop capable of being unloaded at reduced pressure, including a base bottom plate and two wedge-shaped support blocks, where one of the wedge-shaped support blocks serves as a fixed wedge-shaped support block and is welded onto the base bottom plate, and the other of the wedge-shaped support blocks serves as a movable wedge-shaped support block and is connected to the fixed wedge-shaped support block by using a screw rod and a nut. The present invention can effectively unload the single prop at reduced pressure or remove the single prop in a contracted manner, is of a simple structure, is convenient to operate, has a good use effect, overcomes the technical problem that it is difficult to unload a single prop at reduced pressure in this technical feature, and is widely applicable in this technical field.

Abstract: The present invention discloses a method for determining internal stress of a solid filling material, comprising the following steps: step 1) acquiring stress data of the solid filling material, and fitting the stress-strain relationship of the solid filling material; step 2) calculating surface subsidence in the solid filling area on the basis of an equivalent mining height theory with a probability integration method; step 3) calculating the expansion height of fractured zones in the area under a solid-backfill coal mining condition; step 4) calculating the strain in the solid filling material at a distance L from the rear of the stope by combing with step 2) and step 3); step 5) calculating internal stress in the solid filling material at distance L from the rear of the working face. The present invention attains the following beneficial effects: the present invention provides a method for calculating the stress in filling mass for solid-backfill coal mining.