An assembly that fits within a ventilation shaft open to atmosphere and leading from underground ventilation ducts such as to subways prevents surface waters from flooding the underground ducts while maintaining the ventilation. The assembly fits in the ventilation shaft and houses a buoyant float in a chamber surrounding a passageway in fluid communication with the ventilation shaft. A grate covers the passageway. An outside wall of the chamber adjacent the ventilation shaft is open at top to atmosphere and allows flooding water into the chamber, buoying the float upward in the chamber, elevating the passageway above the flooding water. The chamber suitably has means for drainage and admission of flush water to flush flood water debris from the chamber through the drainage.

A tracer diffusion device includes: a first container, for holding a first fluid containing a tracer; a second container, for holding a second fluid; a drilling pipe; wherein, a first end of the drilling pipe is connected to the first container; a second end of the drilling pipe is extended into a borehole; and the second end of the drilling pipe is equipped with a first sealing capsule and a second sealing capsule; a plurality of through holes are arranged on the drilling pipe between the first sealing capsule and the second sealing capsule; a unidirectional driving device, arranged on the drilling pipe, for injecting the first fluid from the first container into the borehole between the first sealing capsule and the second sealing capsule; and a bidirectional driving device, arranged between the second container and the first sealing capsule.

A tracer diffusion device includes: a first container, for holding a first fluid containing a tracer; a second container, for holding a second fluid; a drilling pipe; wherein, a first end of the drilling pipe is connected to the first container; a second end of the drilling pipe is extended into a borehole; and the second end of the drilling pipe is equipped with a first sealing capsule and a second sealing capsule; a plurality of through holes are arranged on the drilling pipe between the first sealing capsule and the second sealing capsule; a unidirectional driving device, arranged on the drilling pipe, for injecting the first fluid from the first container into the borehole between the first sealing capsule and the second sealing capsule; and a bidirectional driving device, arranged between the second container and the first sealing capsule.

A system for forming a cavity in a backfill mixture comprising granular material and water positioned in an at least partially excavated stope. The system includes a base and a drainage tube assembly in an extended condition thereof. The drainage tube assembly extends between a lower end secured to the base and an upper end positioned above an upper surface of the backfill mixture. The extended drainage tube assembly includes a tube portion thereof with a permeable material and defining the cavity therein into which the water from the backfill mixture is drainable, through the permeable material. The system also includes a drainage pipe, for permitting the water that has drained into the cavity of the extended drainage tube assembly to exit the stope.

A system for forming a cavity in a backfill mixture comprising granular material and water positioned in an at least partially excavated stope. The system includes a base and a drainage tube assembly in an extended condition thereof. The drainage tube assembly extends between a lower end secured to the base and an upper end positioned above an upper surface of the backfill mixture. The extended drainage tube assembly includes a tube portion thereof with a permeable material and defining the cavity therein into which the water from the backfill mixture is drainable, through the permeable material. The system also includes a drainage pipe, for permitting the water that has drained into the cavity of the extended drainage tube assembly to exit the stope.

A tracer diffusion device includes: a first container, a second container, a drilling pipe, a unidirectional driving device, and a bidirectional driving device. The first container holds a first fluid containing a tracer. The second container holds a second fluid. A first end of the drilling pipe is connected to the first container; a second end of the drilling pipe is extended into a borehole and equipped with a first sealing capsule and a second sealing capsule. A plurality of through holes are arranged on the drilling pipe between the first sealing capsule and the second sealing capsule. The unidirectional driving device is arranged on the drilling pipe, for injecting the first fluid from the first container into the borehole between the first sealing capsule and the second sealing capsule. The bidirectional driving device is arranged between the second container and the first sealing capsule.

A tracer diffusion device includes: a first container, a second container, a drilling pipe, a unidirectional driving device, and a bidirectional driving device. The first container holds a first fluid containing a tracer. The second container holds a second fluid. A first end of the drilling pipe is connected to the first container; a second end of the drilling pipe is extended into a borehole and equipped with a first sealing capsule and a second sealing capsule. A plurality of through holes are arranged on the drilling pipe between the first sealing capsule and the second sealing capsule. The unidirectional driving device is arranged on the drilling pipe, for injecting the first fluid from the first container into the borehole between the first sealing capsule and the second sealing capsule. The bidirectional driving device is arranged between the second container and the first sealing capsule.

A method for dewatering a coal mine goaf by crossing a neighboring goaf is applicable to a scenario including a first goaf, a second goaf, and a third goaf located sequentially at one side of a roadway. A directional hole mechanism is provided between the roadway and the second goaf as well as between the roadway and the third goaf. The directional hole mechanism passes through a coal seam floor at a bottom of the goaf and is communicated to the second goaf and the third goaf. The directional hole includes a first directional hole and a second directional hole. The first directional hole is communicated to the second goaf, the second directional hole is communicated to the third goaf, and the first directional hole is provided with a casing structure.

A method for dewatering a coal mine goaf by crossing a neighboring goaf is applicable to a scenario including a first goaf, a second goaf, and a third goaf located sequentially at one side of a roadway. A directional hole mechanism is provided between the roadway and the second goaf as well as between the roadway and the third goaf. The directional hole mechanism passes through a coal seam floor at a bottom of the goaf and is communicated to the second goaf and the third goaf. The directional hole includes a first directional hole and a second directional hole. The first directional hole is communicated to the second goaf, the second directional hole is communicated to the third goaf, and the first directional hole is provided with a casing structure.

A mining method is provided without coal pillars with roof-cutting and roadway retaining. This includes, comprising: constructing a gas drainage roadway and eliminating outbursts in a working face transport gate area and track gate area on opposite sides of a first mining working face; constructing various components with an air return roadway. Another end is communicated with the gas drainage roadway by the first process roadway, one end of the working face track gate is communicated with the air return roadway, the other end is communicated with the gas drainage roadway. A ventilation system is formed. This makes full use of the existing gas drainage roadway to meet the roadway layout requirements using the 110 construction method, increasing the use function of the roadway and increasing the reuse rate of the roadway, reducing the roadway engineering quantity before production, shortening the construction period and reduce the cost.