A method for preventing and controlling coal-rock gas disasters by graded control of protective layer drilling

Abstract

The present invention relates to the technical field of safe mining of coal mines, and discloses a method for preventing and controlling coal-rock gas disasters by drilling holes in a graded manner, comprising the following steps: S1, geological survey; S2, borehole pressure relief; S3, hydraulic fracturing; S4, gas extraction; S5, roof deep hole blasting; S6, advanced hole-making energy-absorbing flexible support; S7, grouting reinforcement; S8, continuous control. The method for preventing and controlling coal-rock gas disasters by drilling holes in a graded manner, by integrating multiple functions into a single borehole, achieves resource conservation, cost reduction, and efficiency improvement, effectively reduces environmental interference in the mine, and continuously controls the state of the coal-rock gas system to ensure the timeliness and flexibility of disaster prevention and control, adapts to different geological conditions, strengthens coal mine safety, embodies the dual benefits of green mining and economic optimization, and marks the frontier progress of coal mine safety technology.

Description

Technical Field

[0001] The invention relates to the technical field of safe mining of coal mines, and in particular to a method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer in a graded manner. Background Art

[0002] As one of the main energy industries in my country, coal has greatly supported the development of the country's economy and society. However, with the continuous advancement of science and technology, the speed of underground mining has gradually increased. However, due to the geological deposition of deep coal seams, the mining conditions are poor, and there are three highs and one disturbance problem: "high ground stress, high gas stress, high ground temperature and mining disturbance". The frequency and degree of harm of the highly dangerous and complex coal-rock gas composite dynamic disasters are increasing. The series of dynamic disasters that may be caused, such as coal and gas outbursts, rock bursts, etc., pose a serious threat to coal mine safety production.

[0003] At present, the solutions for controlling underground dynamic disasters in coal mines generally include traditional prevention and control methods such as drilling unloading, blasting unloading, hydraulic fracturing and protective layer mining. However, traditional solutions are generally only aimed at the prevention and control of single disasters such as rock burst or coal and gas outburst. There may be problems such as controlling rock burst but coal and gas outburst disasters continue to occur, or controlling coal and gas outburst but rock burst disasters occur. These solutions often have problems such as being single, ineffective and wasteful of resources.

[0004] In view of this, there is an urgent need for a comprehensive, efficient and sustainable prevention and control method for coal-rock gas complex dynamic disasters, so as to achieve the goals of mine system structure regulation, concentrated stress release of coal and rock mass, gas energy dissipation, construction of advanced cavitation energy-absorbing flexible support system, reduction of the possibility of single or chain instability of the roof, and economic optimization of integrated hierarchical continuous prevention and control, effectively prevent and control coal-rock gas complex dynamic disasters, and improve the safety production level of coal mines. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling and preventing coal-rock gas disasters by graded control of protective layer drilling holes, so as to solve the technical problems existing in existing measures. The method greatly reduces the potential release energy that induces the occurrence of coal-rock gas compound dynamic disasters through graded continuous control methods, performs pre-control in the whole cycle before and during mining, and the one-hole reuse scheme ensures economic optimization, which greatly guarantees the safety of underground mining.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer in a graded manner comprises the following steps:

[0008] S1. Geological Survey:

[0009] Conduct detailed geological surveys of the mines, conduct preliminary analysis of geological structures, coal seam occurrence, gas content, hydrogeological conditions, etc., and collect data on coal seam thickness, inclination, gas content, ground stress, etc. to understand the potential rock burst and gas outburst areas in the mines;

[0010] It is worth noting that the preliminary analysis of geological structure in step S1 is to identify special difficult-to-treat areas such as faults and folds that may appear underground, and the understanding of coal seam occurrence is to determine the mining plan and the location of the protective layer, in order to find and design the area for drilling in the subsequent step S2;

[0011] S2, drilling pressure relief:

[0012] According to the geological survey results obtained by S1 and the specific engineering requirements, the drilling pressure is relieved, the various parameters of the drilling are designed, the drilling area is cleaned, sufficient working space is guaranteed, and ventilation, lighting and safety facilities are checked at the same time to ensure that the operation can be carried out safely. The drilling pressure, drilling speed, torque and other parameters during the drilling process are monitored in real time to ensure that the drilling 7 extends to the designed area;

[0013] S3. Hydraulic fracturing:

[0014] After the drilling described in S1 and S2 is completed, hydraulic fracturing is carried out, a reasonable hydraulic fracturing plan is formulated, the location and scope of the required fracturing area are determined, the equipment is transported to the designated operation site for installation and commissioning, and then high-pressure water is injected into the borehole, sufficient pressure is applied by a high-pressure water pump, and fracturing parameters are adjusted according to monitoring data to ensure that the fracturing effect reaches the expected result;

[0015] It is worth noting that in step S3, hydraulic fracturing aims to use high-pressure water flow to fractur e multi-level coal and rock formations. Its mechanism for preventing and controlling coal-rock gas compound dynamic disasters is that this process will further change the structure of the coal and rock mass, reduce the concentration of the elastic energy of the coal and rock mass, and greatly promote the secondary development of fissures. In addition, the entry of high-pressure water flow will greatly weaken the adsorption capacity of gas on the surface of the coal and rock mass, which is helpful to provide a migration channel for the next step of gas extraction and reduce the risk of rock burst and gas outburst.

[0016] S4. Gas extraction:

[0017] After hydraulic fracturing in S3, gas extraction design is immediately carried out to clarify parameters such as extraction negative pressure, and gas extraction equipment is used to extract gas from the coal seam [protective layer, upper protected layer, lower protected layer] through the boreholes in S2 to reduce gas concentration. Similarly, this process needs to ensure that the pressure does not leak during the extraction process;

[0018] S5. Roof deep hole blasting:

[0019] Continue to drill holes as described in S2, carefully calculate and load the appropriate amount of explosives, and accurately install detonators to ensure that the energy of the blasting can be effectively transmitted and released. After the charge and detonators are installed, the blasting network must be carefully designed and connected to ensure that the detonation sequence and time interval between each blast hole meet the expectations;

[0020] In step S5, the mechanism for preventing and controlling coal-rock gas compound dynamic disasters is that the powerful shock wave and high-temperature and high-pressure gas generated by the explosion of explosives during blasting quickly act on the roof rock, causing cracks and fragments inside the rock. The release of the explosion energy causes a sharp change in the stress state of the rock, and the originally stable rock structure is destroyed, thereby achieving pretreatment of the roof, reducing the roof pressure, and preventing the occurrence of roof accidents;

[0021] S6, advanced hole-making energy-absorbing flexible support:

[0022] If it is found that the roof has a certain impact tendency, then the energy absorbing material is injected into the overlying strata [overlying strata of the protective layer, overlying strata of the upper protected layer, overlying strata of the lower protected layer] of the protective layer and the protected layer [upper protected layer, lower protected layer] or the edge of the goaf with greater disturbance impact, and the drilling described in S2 is continued, and the borehole is enlarged and trimmed by using the hole expansion device, and then the energy absorbing material is injected into the preset position area;

[0023] In step S6, the mechanism of the advanced hole-making energy-absorbing flexible support is that when the injected material is impacted or loaded, it absorbs and consumes huge impact energy through plastic deformation, fracture, energy conversion, shock wave attenuation or chemical reaction inside the material, changes the stress distribution and energy transfer path of the roof, and reduces the propagation and release of energy. This reduces the concentration of ground stress and reduces the risk of rock burst and rock burst.

[0024] S7, grouting reinforcement:

[0025] Continue to drill holes as described in S2, determine the location of the grouting hole and the selection and proportion of the grouting material, insert the grouting pipe into the borehole according to the predetermined plan, start the grouting pump, and inject the configured grouting material into the predetermined position through the grouting pipe;

[0026] In step S7, the prevention and control mechanism of grouting reinforcement is that the slurry diffuses in the coal rock mass, fills the cracks and pores, solidifies after a certain period of time, and forms a consolidated body with certain strength and stability, thereby enhancing the bearing capacity and deformation resistance of the coal rock mass, reducing the stress level in the area of ​​concentrated ground stress, reducing the abnormal distribution and concentrated release of ground stress, and preventing the occurrence of rock stratum slip and collapse, thereby achieving the purpose of reinforcing the roof and floor plates and reducing the occurrence of rock burst;

[0027] S8, continuous control:

[0028] According to the dynamic changes of coal seams and monitoring data, the prevention and control measures are continuously adjusted, and the parameters of drilling unloading, hydraulic fracturing, gas extraction, deep hole blasting of the roof, advanced cavitation energy-absorbing flexible support and grouting reinforcement are adjusted to adapt to the changes in the coal seams and ensure the high efficiency of the prevention and control effects.

[0029] Preferably, in step S2, the mining position for depressurizing the drilling hole is set in the protective layer mining return air tunnel, and specifically, the roof and floor high and low positions are bidirectionally and long-distance directional drilling is carried out along the coal seam direction to ensure that the drilling hole extends to the overlying rock layer of the protective layer, the overlying rock layer range of the upper protective layer or the lower protected layer coal seam, and it is required that after drilling, the structural continuity of the protective layer and the overlying rock layer of the protected layer can be ensured to be destroyed, and the stress concentration of the roof can be weakened, thereby reducing the probability of coal-rock gas composite dynamic disasters;

[0030] It is worth mentioning that in step S2, drilling can create cracks between the protective layer and the protected coal seam and roof, which helps to further release the roof pressure and reduce the probability of rock burst.

[0031] Preferably, the spacing between rows of drill holes in the borehole pressure relief is set to 5-8m, the hole diameter is Φ90-130mm, and the inclination angle is 22°-90°. The specific data are set based on the geological conditions of the mine.

[0032] Preferably, the borehole decompression and hydraulic fracturing in steps S2 and S3 have provided a relatively common migration path (holes and fissures) for gas extraction, so the gas extraction in step 4 can extract the gas in the protective layer and its overlying rock layer (the protected layer and its overlying rock layer) in advance, so as to reduce the accumulation of gas in the coal seam, reduce the gas pressure, and thus reduce the risk of gas explosion and outburst, and realize the effective extraction of the residual gas in the protective layer during the mining process and all the gas in the protected layer to be pre-mined in the next stage, greatly reducing the risk of gas outburst;

[0033] It is worth mentioning that, under good geological conditions, the gas adsorption capacity is weak. After the borehole fissures are developed, gas extraction can achieve better expected results, and the hydraulic fracturing may no longer be carried out.

[0034] Preferably, before the roof deep hole blasting is carried out, it must be ensured that the gas content after gas extraction is less than the minimum concentration limit for blasting.

[0035] Preferably, in step S6, the energy-absorbing material mentioned in the advanced hole-making energy-absorbing flexible support can be made of existing materials, such as polyurethane foam, polystyrene foam, etc.

[0036] Preferably, in step S7, the grouting material mentioned in the grouting reinforcement can be made of existing materials, such as cement concrete, fly ash solid waste filling material or polymer filling reinforcement material.

[0037] Preferably, in the steps of hydraulic fracturing, advanced hole making, energy-absorbing flexible support and grouting reinforcement, the tightness of the hole sealing must be ensured, that is, the pressure does not leak out during the construction process.

[0038] Preferably, the six major control technologies in the steps of drilling pressure relief, hydraulic fracturing, gas extraction, roof deep hole blasting, advance cavitation energy absorption flexible support and grouting reinforcement can all or partially cooperate to play a "series" type of prevention and control enhancement effect, and can also play a "parallel" type of prevention and control when used alone, which can be flexibly adjusted according to the geological conditions of the mine.

[0039] Compared with the related art, the protective layer drilling graded control prevention and control method for coal rock gas disasters provided by the present invention has the following beneficial effects:

[0040] The present invention provides a method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer in a graded manner:

[0041] 1. It can integrate drilling pressure relief, hydraulic fracturing, gas extraction, roof deep hole blasting, advanced cavitation energy-absorbing flexible support, and grouting reinforcement, and realize the continuous control and prevention of one hole for multiple use, fundamentally realizing the integrated prevention and control of coal-rock gas composite dynamic disasters, and realizing resource conservation. Through one hole for multiple uses, the number of drill holes is reduced, the drilling cost and time are saved, and the interference to the mine environment is also reduced. At the same time, the efficiency is improved. By integrating multiple technologies, multiple purposes can be achieved in a single hole, such as pressure relief, gas extraction, reinforcement, etc., which improves the operation efficiency and prevention effect;

[0042] 2. It can realize continuous regulation of the stress field, strain field, seepage field and energy field of the coal-rock gas system, realize continuous monitoring and regulation of coal-rock gas composite dynamic disasters, respond to stratum changes in a timely manner, dynamically adjust prevention and control measures, and ensure timely prevention and control of mine dynamic disasters;

[0043] 3. It can realize advanced pre-mining prevention and control of protected layer mining and in-mining prevention and control during the mining of protective layer. The six major governance technologies can work together in whole or in part to play the role of "series" type prevention and control enhancement, and can also play the role of "parallel" type prevention and control when used alone. It can be flexibly adjusted according to the geological conditions of the mine, with high flexibility, reducing the damage to the mine environment, helping to protect the ecological environment of the mining area, and conforming to the concept of green mining;

[0044] 4. It realizes the integrated hierarchical continuous prevention and control of mine system structure regulation, concentrated stress release of coal and rock mass, gas energy dissipation, advanced cavitation energy absorption flexible support system construction, reduced possibility of single or chain instability of roof, and economic optimization. This technology can effectively prevent and control coal-rock gas compound dynamic disasters and improve the safety production level of coal mines. This plan represents the development trend of coal mine safety technology and has high technical foresight and development potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A diagram illustrating the specific steps of the method for preventing and controlling coal-rock gas disasters by drilling holes in a graded manner in the protective layer provided by the present invention and the effects of each step;

[0046] Figure 2 A schematic diagram of the drilling position design of the protective layer drilling graded control prevention method for coal-rock gas disasters provided by the present invention;

[0047] Figure 3 A "series type" prevention and control principle diagram of the protective layer drilling graded control prevention and control method for coal rock gas disasters provided by the present invention;

[0048] Figure 4 A "parallel type" prevention and control principle diagram of the protective layer drilling graded control prevention and control method for coal rock gas disasters provided by the present invention.

[0049] Numbers in the figure: 1. Protective layer; 2. Overlying rock strata of protective layer; 3. Upper protected layer; 4. Overlying rock strata of upper protected layer; 5. Lower protected layer; 6. Overlying rock strata of lower protected layer; 7. Drilling; 8. Drilling pressure relief; 9. Hydraulic fracturing; 10. Gas extraction; 11. Deep hole blasting pressure relief; 12. Advanced cavitation energy-absorbing flexible support; 13. Grouting reinforcement; 14. Coal-rock-gas combined dynamic disaster; 15. Cracks; 16. High-pressure water flow; 17. Gas; 18. Energy-absorbing material; 19. Grouting material. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0051] Please refer to Figure 1-4 The present invention proposes a method for preventing and controlling coal-rock gas disasters by graded drilling of protective layers, which comprises the following steps:

[0052] S1. Geological Survey:

[0053] Conduct detailed geological surveys of the mines, conduct preliminary analysis of geological structures, coal seam occurrence, gas content, hydrogeological conditions, etc., and collect data on coal seam thickness, inclination, gas content, ground stress, etc. to understand the potential rock burst and gas outburst areas in the mines;

[0054] It is worth noting that the preliminary analysis of geological structure in step S1 is to identify special difficult-to-treat areas such as faults and folds that may appear underground, and the understanding of coal seam occurrence is to determine the mining plan and the location of the protective layer, in order to find and design the area for drilling in the subsequent step S2;

[0055] S2, drilling pressure relief 8:

[0056] According to the geological survey results obtained in S1 and the specific engineering requirements, the drilling pressure is relieved 8, the parameters of the drilling 7 are designed, the drilling area is cleaned, sufficient working space is guaranteed, and ventilation, lighting and safety facilities are checked at the same time to ensure that the operation can be carried out safely. The drilling pressure, drilling speed, torque and other parameters during the drilling process are monitored in real time to ensure that the drilling 7 extends to the designed area;

[0057] S3. Hydraulic fracturing 9:

[0058] After the borehole 7 described in S1 is determined and completed in S2, hydraulic fracturing 9 is carried out, a reasonable hydraulic fracturing 9 plan is formulated, the location and range of the required fracturing area are determined, the equipment is transported to the designated work site for installation and commissioning, and then high-pressure water flow 16 is injected into the borehole 7, sufficient pressure is applied by a high-pressure water pump, and fracturing parameters are adjusted according to monitoring data to ensure that the fracturing effect reaches the expected result;

[0059] It is worth noting that in step S3, hydraulic fracturing 9 aims to use high-pressure water flow 16 to fractur e multi-level coal and rock formations. Its mechanism for preventing and controlling coal-rock gas compound dynamic disaster 14 is that this process will further change the structure of the coal and rock mass, reduce the concentration of the elastic energy of the coal and rock mass, and greatly promote the secondary development of fissures. In addition, the entry of high-pressure water flow 16 will greatly weaken the adsorption capacity of gas on the surface of the coal and rock mass, which is helpful to provide a migration channel for the next step of gas extraction and reduce the risk of rock burst and gas outburst.

[0060] S4, gas extraction 10:

[0061] After hydraulic fracturing 9 at S3, gas extraction 10 design is immediately carried out, parameters such as extraction negative pressure are clarified, and gas extraction 17 in the coal seam [protective layer 1, upper protected layer 3, lower protected layer 5] is extracted through the borehole 7 at S2 using gas extraction 10 equipment to reduce the concentration of gas 17. Similarly, the process needs to ensure that the pressure does not leak during the extraction process;

[0062] S5, roof deep hole blasting 11:

[0063] Continue to drill hole 7 as described in S2, carefully calculate and load the appropriate amount of explosives, and accurately install the detonators to ensure that the energy of the blasting can be effectively transmitted and released. After the charge and detonators are installed, the blasting network must be carefully designed and connected to ensure that the detonation sequence and time interval between each blast hole meet the expectations;

[0064] In step S5, the mechanism for preventing and controlling coal-rock gas compound dynamic disasters is that the powerful shock wave and high-temperature and high-pressure gas generated by the explosion of explosives during blasting quickly act on the roof rock, causing cracks and fragments inside the rock. The release of the explosion energy causes a sharp change in the stress state of the rock, and the originally stable rock structure is destroyed, thereby achieving pretreatment of the roof, reducing the roof pressure, and preventing the occurrence of roof accidents;

[0065] S6, advanced hole-making energy-absorbing flexible support 12:

[0066] If it is found that the roof has a certain impact tendency, then the energy absorbing material 18 is injected into the overlying strata [overlying strata 2 of the protective layer, overlying strata 4 of the upper protected layer, overlying strata 6 of the lower protected layer] of the protective layer 1 and the protected layer [upper protected layer 3, lower protected layer 5] or the edge of the goaf with greater disturbance impact, and the drilling hole 7 described in S2 is continued to be used, and the drilling hole is enlarged and trimmed by using the hole expansion device, and then the energy absorbing material 18 is injected into the preset position area;

[0067] In step S6, the mechanism of the advanced hole-making energy-absorbing flexible support 12 is that when the injected material is impacted or loaded, it absorbs and consumes huge impact energy through plastic deformation, fracture, energy conversion, shock wave attenuation or chemical reaction inside the material, changes the stress distribution and energy transfer path of the top plate, and reduces the propagation and release of energy. Thereby reducing the concentration of ground stress and reducing the risk of rock burst and rock burst;

[0068] S7, grouting reinforcement 13:

[0069] Continue to use the borehole 7 described in S2, determine the position of the grouting hole and the selection and proportion of the grouting material 19, insert the grouting pipe into the borehole 7 according to the predetermined plan, start the grouting pump, and inject the prepared slurry 19 into the predetermined position through the grouting pipe;

[0070] In step S7, the prevention and control mechanism of grouting reinforcement is that the slurry diffuses in the coal rock mass, fills the cracks and pores, solidifies after a certain period of time, and forms a consolidated body with certain strength and stability, thereby enhancing the bearing capacity and deformation resistance of the coal rock mass, reducing the stress level in the area of ​​concentrated ground stress, reducing the abnormal distribution and concentrated release of ground stress, and preventing the occurrence of rock stratum slip and collapse, thereby achieving the purpose of reinforcing the roof and floor plates and reducing the occurrence of rock burst;

[0071] S8, continuous control:

[0072] According to the dynamic changes of the coal seam and the monitoring data, the prevention and control measures are continuously controlled and adjusted to adjust the parameters of drilling pressure relief 8, hydraulic fracturing 9, gas extraction 10, roof deep hole blasting 11, advanced cavitation energy-absorbing flexible support 12 and grouting reinforcement 13 to adapt to the changes in the coal seam and ensure the high efficiency of the prevention and control effect.

[0073] In a further embodiment of the present invention, in the step S2, the mining position of the drilling pressure relief 8 is set in the mining return air tunnel of the protective layer 1, and specifically, the roof and floor high and low positions are bidirectionally long-distance directional drilling 7 is carried out along the coal seam direction to ensure that the drilling 7 extends to the overlying rock layer 2 of the protective layer, the overlying rock layer 4 of the upper protective layer, or the lower protected layer coal seam 5. It is required that after drilling 7, the structural continuity of the protective layer 1 and the overlying rock layers 4 and 6 of the protected layer can be guaranteed to be destroyed, and the stress concentration of the roof is weakened, thereby reducing the probability of the occurrence of the coal-rock gas composite dynamic disaster 14;

[0074] It is worth mentioning that in step S2, the drilling hole 7 can create a crack 15 between the protective layer 1 and the protected coal seam and roof, which helps to further release the roof pressure and reduce the probability of rock burst.

[0075] In a further embodiment of the present invention, the spacing between 7 rows of boreholes in the borehole pressure relief 8 is set to 5-8m, the hole diameter is Φ90-130mm, the inclination angle is 22°-90°, and the specific data is set based on the geological conditions of the mine.

[0076] In a further embodiment of the present invention, the drilling pressure relief 8 and hydraulic fracturing 9 in steps S2 and S3 have provided relatively common migration path holes and fissures for gas extraction 10, so the gas extraction 10 in step 4 can extract the gas in the protective layer and its overlying rock layer in advance, so as to reduce the accumulation of gas in the coal seam, reduce the gas pressure, and thus reduce the risk of gas explosion and outburst, and realize the effective extraction of the residual gas in the protective layer during the mining process and all the gas in the protected layer to be pre-mined in the next stage, greatly reducing the risk of gas outburst;

[0077] It is worth mentioning that, under good geological conditions, the gas 17 has a weak adsorption capacity. After the borehole fissures 15 are developed, the gas extraction 10 can achieve a good expected effect, and the hydraulic fracturing 9 may no longer be performed.

[0078] In a further embodiment of the present invention, before the roof deep hole blasting 11 is performed, it must be ensured that the gas 17 content after gas extraction 10 is less than the minimum concentration limit for blasting.

[0079] In a further embodiment of the present invention, in step S6, the energy absorbing material mentioned in the advanced hole-making energy absorbing flexible support can be made of existing materials, such as polyurethane foam, polystyrene foam, etc.

[0080] In a further embodiment of the present invention, in step S7, the grouting material mentioned in the grouting reinforcement can be an existing material, such as cement concrete, fly ash solid waste filling material or polymer filling reinforcement material.

[0081] In a further embodiment of the present invention, in the steps of hydraulic fracturing 9, advanced hole making energy absorbing flexible support 12 and grouting reinforcement 13, the tightness of the hole sealing must be ensured, that is, the pressure does not leak out during the construction process.

[0082] An ingenious aspect of the present scheme is that the six major control technologies in the steps of drilling pressure relief 8, hydraulic fracturing 9, gas extraction 10, roof deep hole blasting 11, advanced cavitation energy-absorbing flexible support 12 and grouting reinforcement 13 can work together in whole or in part to play a "series" type of prevention and control enhancement effect, and can also play a "parallel" type of prevention and control when used alone. They can be flexibly adjusted according to the geological conditions of the mine, realizing the reuse of one hole for graded continuous control and prevention, fundamentally realizing the integrated prevention and control of coal-rock gas complex dynamic disasters 14, and realizing resource conservation. By using one hole for multiple purposes, the number of drill holes 7 is reduced, the drilling cost and time are saved, and the interference to the mine environment is also reduced. At the same time, the efficiency is improved, and a variety of technologies are integrated to achieve multiple purposes in a single channel, such as pressure relief, gas extraction, reinforcement, etc., thereby improving the operating efficiency and prevention and control effects.

[0083] The above descriptions are only embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any modification or equivalent replacement of the technical solution of the present invention, or direct or indirect application in other related technical fields, without departing from the purpose and scope of the technical solution, are also included in the patent protection scope of the present invention.

Claims

1. A method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer in a graded manner, characterized in that: The steps include: S1. Geological Survey: Conduct detailed geological surveys of the mines, conduct preliminary analysis of their geological structures, coal seam occurrence, gas content, and hydrogeological conditions, and collect data on coal seam thickness, inclination, gas content, and ground stress to understand all possible rock bursts and gas outburst areas in the mines; S2, drilling pressure relief (8): According to the geological survey results obtained in S1 and the specific engineering requirements, the drilling pressure is relieved (8), the various parameters of the drilling (7) are designed, the drilling area is cleaned, sufficient working space is guaranteed, and ventilation, lighting and safety facilities are checked to ensure that the operation can be carried out safely before starting the construction. The drilling pressure, drilling speed and torque parameters during the drilling process are monitored in real time to ensure that the drilling (7) extends to the designed area; S3. Hydraulic fracturing (9): After the borehole (7) described in S1 is determined and completed in S2, hydraulic fracturing (9) is carried out, a reasonable hydraulic fracturing (9) plan is formulated, the location and range of the required fracturing area are determined, the equipment is transported to the designated work site for installation and commissioning, and then a high-pressure water flow (16) is injected into the borehole (7), sufficient pressure is applied by a high-pressure water pump, and the fracturing parameters are adjusted according to the monitoring data to ensure that the fracturing effect reaches the expected result; S4. Gas extraction (10): After hydraulic fracturing (9) at S3, gas extraction (10) design is immediately carried out to clarify the extraction negative pressure parameters, and the gas extraction (10) equipment is used to extract the gas (17) in the coal seam through the borehole (7) at S2 to reduce the concentration of the gas (17) and ensure that the pressure does not leak during the extraction process; S5. Roof deep hole blasting (11): Continue to drill holes (7) as described in S2, carefully calculate and load the appropriate amount of explosives, and accurately install detonators to ensure that the energy of the blasting can be effectively transmitted and released. After the charge and detonators are installed, the blasting network must be carefully designed and connected to ensure that the detonation sequence and time interval between each blast hole meet expectations; S6, advanced hole-making energy-absorbing flexible support (12): If it is found that the roof has a certain impact tendency, then the energy absorbing material (18) is injected into the overlying rock layer of the protective layer (1) and the protected layer or the edge of the goaf affected by the disturbance, and the drilling hole (7) described in S2 is continued, and the drilling hole is enlarged and trimmed by using the hole expansion device, and then the energy absorbing material (18) is injected into the preset position area; S7, Grouting reinforcement (13): Continue to use the drilling hole (7) described in S2, determine the position of the grouting hole and the selection and proportion of the grouting material (19), insert the grouting pipe into the drilling hole (7) according to the predetermined plan, start the grouting pump, and inject the configured grouting material (19) into the predetermined position through the grouting pipe; S8, continuous control: According to the dynamic changes of the coal seam and the monitoring data, the prevention and control measures are continuously regulated and adjusted, and the parameters of drilling pressure relief (8), hydraulic fracturing (9), gas extraction (10), roof deep hole blasting (11), advanced cavitation energy absorption flexible support (12) and grouting reinforcement (13) are adjusted to adapt to the changes of the coal seam and ensure the high efficiency of the prevention and control effect.

2. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1 is characterized in that: The mining position of the drilling pressure relief (8) is set in the return air tunnel of the protective layer (1). Specifically, the roof and floor high and low positions are bidirectionally and long-distance directional drilling (7) is carried out along the direction of the coal seam to ensure that the drilling (7) extends to the overlying rock layer (2) of the protective layer, the overlying rock layer (4) of the upper protective layer or the lower protected layer coal seam (5). It is required that after the drilling (7), the structural continuity of the protective layer (1) and the overlying rock layer of the protected layer can be destroyed, the stress concentration of the roof can be weakened, and the probability of the occurrence of coal-rock gas composite dynamic disaster (14) can be reduced.

3. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1 is characterized in that: The spacing between rows of boreholes (7) in the borehole pressure relief (8) is set to 5-8m, the hole diameter is Φ90-130mm, and the inclination angle is 22°-90°.

4. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1, characterized in that: When the geological conditions are good, the gas (17) has a weak adsorption capacity, and after the borehole fissures (15) are developed, the gas extraction (10) can achieve a good expected effect, and the hydraulic fracturing (9) is no longer performed.

5. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1, characterized in that: Before the roof deep hole blasting (11) is carried out, it must be ensured that the gas (17) content after gas extraction (10) is less than the minimum concentration limit for blasting.

6. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1, characterized in that: In the step S6, the energy absorbing material (18) mentioned in the advanced hole-making energy absorbing flexible support (12) is polyurethane foam or polystyrene foam.

7. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1, characterized in that: In the step S7, the grouting material (19) mentioned in the grouting reinforcement (13) is cement concrete, fly ash solid waste filling material or polymer filling reinforcement material.

8. The method for preventing and controlling coal-rock gas disasters by drilling holes in a protective layer by graded control according to claim 1, characterized in that: In the steps of hydraulic fracturing (9), advanced hole making energy absorbing flexible support (12) and grouting reinforcement (13), the tightness of the hole sealing must be ensured, that is, the pressure does not leak out during the construction process.

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