Method for preventing rock burst and gas in mining area based on hydraulic fracturing and Y-shaped ventilation

Abstract

The present application belongs to the field of deep coal seam mining, and particularly relates to a mining area rock burst and gas prevention and control method based on hydraulic fracturing and Y-shaped ventilation; the present application constructs a haulage uphole and a track uphole on both sides of a mining area trend, then constructs a bedding long borehole to connect the two, and based on the bedding long borehole, hydraulic fracturing and gas extraction are carried out on the coal seam in the mining area, so that the pressure relief and gas pre-extraction of the coal seam in the whole mining area can be realized. Then, one inclined advancing working face is arranged on each side of the haulage uphole and the track uphole, and a plurality of strike advancing working faces are arranged between the two inclined advancing working faces, so that all the working faces except the inclined advancing working face on the side of the haulage uphole can adopt Y-shaped ventilation. Further, the original track uphole is used as the haulage uphole of the next mining area. The present application can greatly reduce the roadway excavation workload, improve the gas ventilation quality during coal mining and the overall recovery rate of the mining area.

Description

Technical Field

[0001] This invention belongs to the field of deep coal seam mining, specifically relating to a method for preventing rockburst and gas in mining areas based on hydraulic fracturing and Y-shaped ventilation. Background Technology

[0002] Hydraulic fracturing of coal seams creates a fracture network, releasing some of the accumulated pressure or energy. Gas extraction based on this fracture network is a crucial method for preventing rockbursts and gas leaks. However, in current working face production, roadway decompression and gas extraction boreholes need to be pre-constructed during roadway excavation; similarly, face decompression and gas extraction boreholes need to be pre-constructed before coal seam mining. This dispersed construction of decompression and gas extraction boreholes significantly increases the number of construction steps, especially in mining areas with multiple working faces, where each face requires separate roadway decompression and gas extraction procedures.

[0003] Pre-drainage cannot completely remove gas from the coal seam; gas will still be released during mining. Therefore, efficient ventilation is crucial for gas control, such as Y-shaped ventilation. However, existing Y-shaped ventilation systems require a separate return air incline, increasing the workload of roadway construction. Furthermore, the existing coal pillars (including section pillars and incline pillars) in the mining area are numerous, and the overall recovery rate of the mining area needs to be improved.

[0004] Therefore, improving the efficiency of gas pre-extraction and the effect of rockburst prevention, improving the quality of gas ventilation during coal mining, reducing the amount of roadway excavation, and increasing the recovery rate of mining areas have become the key to high-quality mining of deep coal seams. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a method for preventing rockburst and gas in mining areas based on hydraulic fracturing and Y-shaped ventilation. The method includes the following steps: S1: Constructing a haulage incline and a track incline along the dip direction on both sides of the mining area's strike; drilling long boreholes along the bedding plane from the haulage incline to the track incline, and performing hydraulic fracturing and gas pre-drainage on the coal seam within the mining area based on these long boreholes; S2: Arranging a dip-advance working face near the haulage incline and the track incline side respectively; sequentially arranging multiple strike-advance working faces along the dip direction between the two strike-advance working faces; S3: Excavating the track roadway and haulage roadway of the first strike-advance working face, as well as the cut-outs of all strike-advance working faces; excavating a connecting roadway along the track incline from the cut-out of the last strike-advance working face; mining back and leaving a roadway along the goaf in the haulage roadway, using... Y-shaped ventilation; S4: For subsequent forward working faces, use the goaf roadway of the previous forward working face as the track roadway of this working face, and carry out mining and ventilation according to step S3; S5: Use the track roadway of the original first forward working face located in the inclined forward working face on the haulage incline side as the cut-in, use the haulage incline as the haulage roadway, and use the goaf roadway of the last forward working face as the connecting roadway; prepare the track roadway to connect the cut-in and the connecting roadway; mine; S6: Use the track incline as the haulage roadway of the inclined forward working face on the track incline side; prepare the track roadway and open the cut-in; mine and leave the haulage roadway along the goaf, using Y-shaped ventilation; S7: Use the original track incline as the haulage incline of the next mining area, and carry out rockburst and gas prevention and coal seam mining work in the next mining area according to steps S1-S6.

[0006] Preferably, in step S1, fresh air is introduced from the transport uphill section, and the fresh air flows through the long borehole along the bedding plane and its hydraulic fracturing fracture network, becoming exhaust air before reaching the track uphill section and being discharged through the track uphill section.

[0007] Preferably, in step S2, the total width of the advancing working face is equal to the advancing length of the inclined advancing working face.

[0008] Preferably, in step S2, the boundary of the inclined advancing face on the uphill side of the transport is the stop line of the advancing face, and the boundary of the inclined advancing face on the uphill side of the track is the cutting position of the advancing face.

[0009] Preferably, in steps S3 and S4, the transport roadway is close to the subsequent forward working face.

[0010] Preferably, in step S3, fresh air is introduced from the transport uphill section, and the fresh air flows into the track roadway and the transport roadway at the same time. After reaching the mining area, it becomes exhaust air, and the exhaust air is discharged sequentially through the goaf roadway, the cut-out of the subsequent forward working face, the connecting roadway, and the track uphill section.

[0011] Preferably, in step S4, the transport tunnel of the working face is excavated from the transport uphill.

[0012] Preferably, in step S4, for the final advancing working face, fresh air is introduced from the transport uphill section. The fresh air simultaneously flows into the track roadway and the transport roadway. After reaching the stope, it becomes exhaust air. The exhaust air is discharged sequentially through the goaf roadway connecting roadway and the track uphill section.

[0013] Preferably, in step S5, a small coal pillar is left between the inclined advancing face on the transport uphill side and the goaf, and a track roadway is constructed by excavating along the goaf; a sealing retaining wall is constructed at the track roadway of the first advancing face directly opposite the small coal pillar, and a sealing retaining wall is constructed in the connecting roadway within the inclined advancing face on the transport uphill side; and the goaf is filled with filling material.

[0014] Preferably, in step S5, the haulage uphill inclined advancing face is mined from the cut-in point towards the connecting roadway until it reaches the connecting roadway. The connecting roadway directly opposite the haulage uphill inclined advancing face is used as the finishing roadway for withdrawing the coal mining equipment.

[0015] Preferably, in step S5, U-shaped ventilation is used during the mining process. Fresh air is introduced from the haulage uphill, flows into the haulage roadway, and becomes exhaust air after reaching the mining area. The exhaust air is discharged sequentially through the connecting roadway and the track uphill.

[0016] Preferably, in step S6, the sealing retaining wall in the connecting roadway is removed; a small coal pillar is left between the working face and the goaf on the inclined side of the track and the track roadway is constructed by excavating along the goaf.

[0017] Preferably, in step S6, fresh air is introduced from the transport uphill section, and after passing through the connecting roadway, the fresh air flows into the track roadway and the transport roadway simultaneously. After reaching the mining area, it becomes exhaust air, and the exhaust air is discharged sequentially through the goaf roadway and the track uphill section.

[0018] The inventive points and beneficial technical effects of this invention are as follows: 1. This invention involves constructing a transport uphill along the dip direction on one side of the mining area's strike, and constructing a long borehole along the dip direction on the other side of the mining area's strike. The long borehole is used to construct a long borehole along the seam. Based on the long borehole, hydraulic fracturing and gas extraction are performed on the coal seam within the mining area. This can achieve depressurization and pre-extraction of gas in the entire mining area, thereby concentrating and advancing the hydraulic fracturing and gas extraction processes. This provides a safety guarantee for the subsequent roadway excavation and working face recovery within the entire mining area, eliminating the need to construct depressurization and gas extraction boreholes.

[0019] 2. Furthermore, a dipping face is arranged on each side of the haulage incline and the track incline, and several directional ...

[0020] 3. Based on the working face layout in the above mining area, the present invention further uses the original track uphill as the transport uphill for the next mining area, so that only one or two small coal pillars are left in the mining area, and no coal pillars are left between adjacent mining areas, and the overall recovery rate of the mining area reaches about 99.8%. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the construction of long boreholes along the bedding plane in the mining area of ​​this invention.

[0022] Figure 2 This is a schematic diagram of the working face layout in the mining area of ​​this invention.

[0023] Figure 3 This is a schematic diagram of the first working face in the mining area of ​​this invention.

[0024] Figure 4 This is a schematic diagram of the layout of the second working face in the mining area of ​​this invention.

[0025] Figure 5 This is a schematic diagram of the layout of the fourth working face in the mining area of ​​this invention.

[0026] Figure 6 This is a schematic diagram of the fourth working face in the mining area of ​​this invention.

[0027] Figure 7 This is a schematic diagram of the layout of the fifth working face in the mining area of ​​this invention.

[0028] Figure 8 This is a schematic diagram of the fifth working face in the mining area of ​​this invention.

[0029] Figure 9 This is a schematic diagram of the layout of the sixth working face in the mining area of ​​this invention.

[0030] Figure 10 This is a schematic diagram of the sixth working face in the mining area of ​​this invention.

[0031] In the diagram: 11-Transport uphill; 12-Track uphill; 13-Long borehole along the bedding plane; 14-Stop mining line; 21-Track roadway; 22-Transport roadway; 23-Cut-out; 24-Connecting roadway; 25-Mining area; 26-Goaf roadway; 31-Goaf area; 32-Backfill material; 33-Sealing retaining wall; 34-Small coal pillar. Detailed Implementation

[0032] The specific embodiments of the present invention will now be described in conjunction with the accompanying drawings.

[0033] like Figures 1-10 As shown, this invention proposes a method for preventing rockburst and gas in mining areas based on hydraulic fracturing and Y-shaped ventilation, which includes the following steps.

[0034] S1: As Figure 1 As shown, a haulage incline 11 is constructed along the dip direction on one side of the mining area's strike, and this incline 11 connects to the main haulage roadway. On the other side of the mining area's strike, a track incline 12 is constructed along the dip direction, and this track incline 12 connects to the return air roadway. Within the entire mining area, long boreholes 13 are drilled from the haulage incline 11 to the track incline 12. Based on these long boreholes 13, hydraulic fracturing is performed on the coal seams within the mining area, achieving depressurization of the coal seams throughout the entire mining area. Then, fresh air is introduced from the haulage incline 11. The fresh air flows through the long boreholes 13 and the hydraulic fracturing network, becoming exhaust air before reaching the track incline 12, and is discharged through the track incline 12, achieving pre-drainage of gas from the coal seams throughout the entire mining area. Subsequent roadway excavation and face mining within the entire mining area do not require the construction of depressurization and gas drainage boreholes.

[0035] In this embodiment, the mining area has a strike length of 1400m and a dip width of 800m.

[0036] In this invention, dip refers to the dip direction of the coal seam, and strike refers to the strike direction of the coal seam; in the diagram, strike is the left-right direction, and dip is the front-back direction; dip and strike are professional geological terms that express the direction of strata, and will not be elaborated here.

[0037] S2: As Figure 2 As shown, a fifth working face advancing along the dip is arranged on the side of the mining area near the transport incline 11; a sixth working face advancing along the dip is arranged on the side of the mining area near the track incline 12; between the sixth and fifth working faces, four working faces advancing along the strike are arranged sequentially along the dip, namely the first, second, third, and fourth working faces; wherein, the boundary of the fifth working face is the stop line 14 of the four working faces advancing along the strike, and the boundary of the sixth working face is the cut-in position 23 of the four working faces advancing along the strike.

[0038] The width of each of the six working faces is 200m. The advancing length from the first to the fourth working face is 1000m, and the advancing length of the fifth and sixth working faces is 800m.

[0039] S3: As Figures 2-4 As shown, the track roadway 21 and the transport roadway 22 of the first working face are excavated from the transport uphill 11, wherein the transport roadway 22 is close to the second working face; starting from the track roadway 21 of the first working face, four cut-outs 23 of the working faces advancing along the strike are excavated; then, based on the cut-out 23 of the fourth working face, the connecting roadway 24 is excavated along the strike towards the track uphill 12.

[0040] Starting from cut 23, the first working face is mined back towards stop line 14, and goaf roadway 26 is formed by leaving a goaf roadway along the haulage roadway 22. Goaf refers to the goaf area 31 formed by the mining of the first working face. Goaf roadway leaving is a well-known technology in the field and will not be described in detail here. Y-shaped ventilation is adopted during the mining process to improve the gas ventilation quality during coal mining. Specifically, fresh air is introduced from the haulage incline 11. The fresh air flows into the track roadway 21 and the haulage roadway 22 at the same time. After reaching the mining area 25, it becomes exhaust air. The exhaust air is discharged sequentially through the goaf roadway 26, cut 23 from the second to the fourth working face, connecting roadway 24, and track incline 12.

[0041] S4: As Figures 4-6 As shown, for the second to fourth working faces, the goaf roadway 26 of the previous working face is used as the track roadway 21 of this working face, and the transport roadway 22 of this working face is excavated from the transport uphill 11, wherein the transport roadway 22 is close to the next advancing working face.

[0042] Referring to step S3, mining and ventilation are carried out on the second to fourth working faces. For the second and third working faces, mining begins from the cut-in 23 and proceeds towards the stop line 14. The transport roadway 22 is left along the goaf to form the goaf roadway 26. Y-shaped ventilation is used during mining to improve the quality of gas ventilation during coal mining. Specifically, fresh air is introduced from the transport incline 11 and flows into the track roadway 21 and the transport roadway 22. After reaching the stope 25, it becomes exhaust air. The exhaust air is discharged sequentially through the goaf roadway 26, the cut-in 23 of the subsequent working face advancing along the strike, the connecting roadway 24, and the track incline 12. For the fourth working face, mining begins from the cut-off point 23 towards the stop line 14, and a gob-side roadway 26 is formed by leaving a roadway along the gob in the transport roadway 22. During the mining process, Y-shaped ventilation is adopted to improve the quality of gas ventilation during coal mining. Specifically, fresh air is introduced from the transport incline 11, and the fresh air flows into the track roadway 21 and the transport roadway 22 at the same time. After reaching the mining area 25, it becomes exhaust air, and the exhaust air is discharged in sequence through the gob-side roadway 26, the connecting roadway 24, and the track incline 12.

[0043] S5: As Figures 7-8As shown, a small coal pillar 34 is left between the fifth working face and the goaf 31, and the track roadway 21 of the fifth working face is constructed by excavating along the goaf. The track roadway 21 of the original first working face, which is located in the fifth working face, is used as the cut-in 23 of the fifth working face. The transport uphill 11 is used as the transport roadway 22 of the fifth working face. The goaf roadway 26 of the fourth working face is also used as the connecting roadway 24 to connect the track roadway 21 and the track uphill 12 of the fifth working face. A sealing retaining wall 33 is constructed at the track roadway 21 of the first working face directly opposite the small coal pillar 34. A sealing retaining wall 33 is also constructed in the connecting roadway 24 in the fifth working face. The empty roadway in the fifth working face is filled with filling material 32.

[0044] Starting from the cut-off point 23, the fifth working face is mined back towards the connecting roadway 24 until it reaches the connecting roadway 24. The connecting roadway 24, which is directly opposite the fifth working face, is used as the closing roadway for the fifth working face to withdraw the coal mining equipment. During the mining process, U-shaped ventilation is adopted. Specifically, fresh air is introduced from the transport uphill 11 (the part outside the mining area). After the fresh air flows into the transport roadway 22, it reaches the mining area 25 and becomes exhaust air. The exhaust air is discharged sequentially through the connecting roadway 24 and the track uphill 12.

[0045] The width of the small coal pillar 34 is 2m-4m, and the width of the fifth working face in step S2 includes the width of the small coal pillar 34.

[0046] In order to further reduce the amount of roadway excavation and further improve the mining efficiency, the retreat roadway during the retreat of the first to fourth working faces can be retained. The retreat roadway is located at the stop line 14. At this time, there is no need to leave small coal pillars 34 and no need to carry out roadway excavation along the goaf. The retreat roadway from the first to the fourth working faces can be directly used as the track roadway 21 of the fifth working face.

[0047] S6: As Figures 9-10 As shown, the sealing retaining wall 33 in the connecting roadway 24 is removed; a small coal pillar 34 is left between the sixth working face and the goaf 31; the track roadway 21 of the sixth working face is constructed by excavating along the goaf; the track uphill 12 is used as the transport roadway 22 of the sixth working face; and the cut-in hole 23 is opened to connect the track roadway 21 and the transport roadway 22.

[0048] Starting from the cut-off point 23, the sixth working face is mined back towards the connecting roadway 24, and the transport roadway 22 is left along the goaf to form the goaf roadway 26. During the mining process, Y-shaped ventilation is adopted to improve the gas ventilation quality during coal mining. Specifically, fresh air is introduced from the transport incline 11 (the part outside the mining area), and after passing through the connecting roadway 24, the fresh air flows into the track roadway 21 and the transport roadway 22 at the same time. After reaching the mining area 25, it becomes exhaust air, and the exhaust air is discharged in sequence through the goaf roadway 26 and the track incline 12 (the part outside the mining area).

[0049] S7: Use the goaf roadway 26 (original track uphill 12) of the sixth working face as the transport uphill 11 of the next mining area, and carry out the rock burst prevention and gas control and coal seam mining work of the next mining area in accordance with steps S1-S6.

[0050] This invention is not limited to the preferred embodiments described above. Anyone can derive other methods in various forms under the guidance of this invention. Any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for preventing rockburst and gas in mining areas based on hydraulic fracturing and Y-shaped ventilation, characterized in that, include: S1: Construct transport inclines and track inclines along the dip on both sides of the mining area; construct long boreholes along the bedding plane from the transport incline to the track incline, and perform hydraulic fracturing and gas pre-drainage on the coal seams in the mining area based on the long boreholes along the bedding plane. S2: Arrange a directional advancing working face on the side close to the transport uphill side and the side close to the track uphill side respectively; arrange multiple directional advancing working faces in sequence along the directional direction between the two directional advancing working faces; S3: Excavate the track roadway and transport roadway of the first strike advancing face, as well as the cut-in of all strike advancing faces; excavate the connecting roadway uphill along the track from the cut-in of the last strike advancing face; mine back and leave the transport roadway along the goaf, using Y-shaped ventilation; S4: For subsequent forward working faces, the goaf roadway of the previous forward working face is used as the track roadway of this working face, and mining and ventilation are carried out with reference to step S3. S5: Take the track roadway located in the inclined advancing face on the haulage uphill side of the original first strike advancing face as the cut-in, take the haulage uphill as the haulage roadway, and take the goaf roadway of the last strike advancing face as the connecting roadway; prepare the track roadway to connect the cut-in and the connecting roadway; mining; S6: Use the track uphill as the transport roadway for the track uphill side-dipping advance working face; prepare the track roadway and open the cut-in; mine back and leave the transport roadway along the goaf, and use Y-shaped ventilation; S7: Use the original track uphill as the transport uphill for the next mining area, and carry out rock burst and gas prevention and coal seam mining work in the next mining area according to steps S1-S6; In step S1, fresh air is introduced from the transport uphill section. The fresh air flows through the long borehole along the bedding plane and its hydraulic fracturing fracture network, becomes exhaust air, and then reaches the track uphill section and is discharged through the track uphill section. In step S2, the total width of the advancing face is the advancing length of the inclined face; the boundary of the inclined face on the transport uphill side is the stop line of the advancing face, and the boundary of the inclined face on the track uphill side is the cutting position of the advancing face. In step S3, fresh air is introduced from the transport uphill section. The fresh air flows into the track roadway and the transport roadway at the same time. After reaching the mining area, it becomes exhaust air. The exhaust air is discharged sequentially through the goaf roadway, the cut-out of the subsequent forward working face, the connecting roadway, and the track uphill section. In step S4, the transport roadway of this working face is excavated from the transport incline; for the final forward working face, fresh air is introduced from the transport incline, and the fresh air flows into the track roadway and the transport roadway at the same time. After reaching the stope, it becomes exhaust air, and the exhaust air is discharged in sequence through the goaf roadway connecting roadway and the track incline. In step S5, a small coal pillar is left between the inclined advancing face on the transport uphill side and the goaf, and a track roadway is constructed by excavating along the goaf; a sealing retaining wall is constructed at the track roadway of the first advancing face directly opposite the small coal pillar, and a sealing retaining wall is constructed in the connecting roadway within the inclined advancing face on the transport uphill side; and the goaf is filled with filling material.

2. The method for preventing rockbursts and gas explosions according to claim 1, characterized in that, In step S5, the haulage uphill inclined advancing face is mined from the cut-in point towards the connecting roadway until it reaches the connecting roadway. The connecting roadway directly opposite the haulage uphill inclined advancing face is used as the finishing roadway for withdrawing the coal mining equipment.

3. The method for preventing rockbursts and gas explosions according to claim 2, characterized in that, In step S5, U-shaped ventilation is used during the mining process. Fresh air is introduced from the haulage uphill, flows into the haulage roadway, and becomes exhaust air after reaching the mining area. The exhaust air is discharged sequentially through the connecting roadway and the track uphill.

4. The method for preventing rockbursts and gas explosions according to claim 3, characterized in that, In step S6, the sealing retaining wall in the connecting roadway is removed; a small coal pillar is left between the working face and the goaf on the inclined side of the track and the track roadway is constructed by excavating along the goaf.

5. The method for preventing rockbursts and gas explosions according to claim 4, characterized in that, In step S6, fresh air is introduced from the transport uphill section. After passing through the connecting roadway, the fresh air flows into the track roadway and the transport roadway. After reaching the mining area, it becomes exhaust air. The exhaust air is discharged sequentially through the goaf roadway and the track uphill section.

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