Graded control and uniform pressure relief method for wide coal pillar high-stress dangerous area

Abstract

The invention belongs to the technical field of coal seam pressure relief and permeability improvement, and relates to a wide coal pillar high stress dangerous area grading control and uniform pressure relief method which comprises the following steps: dividing a risk area into a high stress concentration area, a general stress concentration area, a disturbance stress area and a low stress area; according to the stress grade of the risk area, hydraulic slotting and drilling arrangement parameters of the corresponding area are determined, and the parameters comprise the drilling interval, the coal hole section slotting interval, the single-tool slotting time and the single-tool coal cutting amount; layer-crossing drilling is conducted on the risk areas of different stress grades in the bottom plate roadway, and layer-crossing drilling hydraulic slotting operation is conducted; the energy in the hydraulic slotting pressure relief process is monitored, so that the pressure relief effect is evaluated; in the coal roadway tunneling or working face stoping period, the drilling cutting quantity index S is adopted to predict the local pressure relief effect, and when the drilling cutting quantity index S exceeds a critical value, local pressure relief measures are taken; and when the drilling cutting quantity index S is lower than the critical value, the next round of coal roadway tunneling or working face stoping operation is carried out.

Description

Technical Field

[0001] This invention belongs to the field of coal seam decompression and permeability enhancement technology, and relates to a method for graded control and uniform decompression of high-stress dangerous areas in wide coal pillars. Background Technology

[0002] Coal is my country's primary energy source, and its mining typically involves arranging longwall faces within the coal seam to transport the coal to the surface. During the arrangement of these longwall faces, coal pillars are left between them. To isolate harmful gases from the goaf of adjacent longwall faces and maintain the stability of the roadway for the next longwall face, the width of these pillars is generally 5–10 meters; these are called small coal pillars. The stress on small coal pillars can be approximated as a uniformly distributed load. However, another type of coal pillar exists, formed due to special factors such as geological structure and mining deployment, and can be 30–50 meters wide or even wider; these are called wide coal pillars. After the surrounding coal seam of a wide coal pillar is mined, the surrounding rock stress transfers to the wide coal pillar, resulting in a significant difference in stress distribution between the wide and small coal pillars. The internal stress levels of wide coal pillars vary considerably, exhibiting three different stress environments: high stress concentration areas, general stress concentration areas, and initial stress areas.

[0003] Currently, commonly used pressure relief measures include large-diameter borehole pressure relief, pre-splitting blasting technology, coal seam water injection softening, and hydraulic pressure relief. Large-diameter boreholes, pre-splitting blasting, coal seam water injection, and hydraulic fracturing technologies primarily employ uniform technical parameters to achieve large-scale pressure relief and permeability enhancement in the coal seam. These technologies achieve good application results for coal seams with simple stress conditions and low stress concentration. However, for coal seams with multiple stress conditions and high stress levels, they cannot effectively solve the problem of pressure relief and permeability enhancement in high-stress areas. In contrast, hydraulic perforation and hydraulic slotting technologies mainly focus on localized pressure relief and permeability enhancement. Hydraulic perforation mainly erodes the coal seam around the borehole along the radial direction, but its effective range is relatively small, and the erosion of the coal seam is uneven. Hydraulic slotting technology mainly cuts flat slots in the coal body perpendicular to the borehole radial direction. This technology has a larger range of action, more uniform pressure relief and permeability enhancement, and can achieve fixed-point slotting and coal extraction, uniformly cutting coal borehole sections to achieve the goal of precise pressure relief and permeability enhancement. It is an important technical means to achieve uniform pressure relief in wide coal pillars.

[0004] However, currently, in the field of coal seam mining, there is a lack of methods for graded control of coal seam stress, and also a lack of effective ways to achieve uniform stress relief between areas with different stress levels. This leads to situations where, in wide coal pillar areas, the coal body may experience insufficient or excessive stress relief in certain areas. When coal seam mining is carried out in such unevenly stressed areas, dynamic disasters are highly likely to occur, posing a serious threat to the safety and production of coal mining. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for graded control and uniform pressure relief of high-stress dangerous areas in wide coal pillars. This method can achieve graded control of high-stress dangerous areas in wide coal pillars and formulate corresponding pressure relief parameters for each zone to achieve uniform pressure relief throughout the entire wide coal pillar area. This can effectively avoid secondary stress concentration and ensure safe production in coal roadway excavation and longwall mining, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for graded control and uniform pressure relief of high-stress hazardous areas in wide coal pillars includes the following steps:

[0008] (1) Classify the risk areas of wide coal pillars: Determine the vertical stress distribution of the wide coal pillar area through numerical simulation or mechanical calculation methods, and classify the risk areas into high stress concentration areas, general stress concentration areas, initial stress areas and low stress areas according to the degree of stress concentration.

[0009] (2) Divide and manage risk areas of different levels: Determine the hydraulic slotting borehole layout parameters of the corresponding areas according to the stress level of the risk areas, including borehole spacing, coal section slotting spacing, single-blade slotting time and single-blade coal cutting amount.

[0010] (3) Drill through layers in the bottom slab tunnel to risk areas with different stress levels, and perform hydraulic cutting operations to form grooves in the through-layer drilling.

[0011] (4) Monitor the energy level during the hydraulic slit depressurization process and evaluate the depressurization effect based on the energy index;

[0012] (5) During the excavation of coal roadways or the mining of working faces, the drill cuttings quantity index S is used to predict the local pressure relief effect. When the drill cuttings quantity index S exceeds the critical value, local pressure relief measures are taken.

[0013] (6) After taking local pressure relief measures, when the drill cuttings volume index S is lower than the critical value, the next round of coal roadway excavation or working face mining operation shall be carried out.

[0014] Further, in step (1), the stress in the high stress concentration zone is greater than 2.0σ0, the stress in the general stress concentration zone is between 1.5σ0 and 2.0σ0, the stress in the disturbed stress zone is between 1.0σ0 and 1.5σ0, and the stress in the low stress zone is less than 1.0σ0, where σ0 is the original stress value of the coal seam.

[0015] Furthermore, in step (2), for high stress concentration areas, the spacing of hydraulic slit boreholes is 5×5 meters, the spacing of the slots formed by the slits in the coal borehole section is 2 meters, the single-blade slit cutting time is 15 to 20 minutes, and the single-blade coal cutting amount is 0.5 to 0.6 tons.

[0016] Furthermore, in step (2), for general stress concentration areas, the spacing of hydraulic slit boreholes is 6-8 meters × 6-8 meters, the spacing of the slots formed by the slits in the coal borehole section is 2-3 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.4-0.5 tons.

[0017] Furthermore, in step (2), for the disturbed stress zone, the spacing of the hydraulic slit boreholes is 8-10 meters × 8-10 meters, the spacing of the slots formed by the slits in the coal borehole section is 3-4 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.3-0.4 tons.

[0018] Furthermore, in step (3), an ultra-high pressure hydraulic slitting device is used to perform hydraulic slitting operations for drilling through layers, and a backward slitting method is adopted.

[0019] Furthermore, in step (4), microseismic monitoring technology is used to monitor the energy level during the hydraulic slit depressurization process, and the energy index Q of microseismic monitoring is used to evaluate the depressurization effect. The energy index Q after hydraulic slit operation in the initial stress zone is used as the basis for the evaluation. 初 Based on this, the maximum energy Q of a single microseismic monitoring in a high stress concentration area is... 高max Total energy Q 高总 All below 10 4 J, and the total daily energy Q 高日总 When the stress level is less than 1.2 times the corresponding index of the initial stress zone, it is considered that the pressure relief is effective.

[0020] Otherwise, hydraulic slit cutting measures should be added to the corresponding area until the corresponding area meets the requirements for effective pressure relief.

[0021] Furthermore, in step (5), the predicted borehole depth for the drill cuttings quantity index S is 10 to 12 meters, and the critical values ​​for drill cuttings quantity in the ranges of 1 to 4 meters, 4 to 8 meters, and 8 to 12 meters are 2.5 kg / m, 2.8 kg / m, and 3.5 kg / m, respectively. When the drill cuttings quantity index S exceeds the critical value, large-diameter in-seam drilling or pre-splitting blasting technology is adopted for local pressure relief.

[0022] Furthermore, the diameter of the large-diameter in-seam borehole is 94–133 mm, and the spacing is 3–5 m; the spacing of the boreholes in the pre-splitting blasting technology is 10–15 m, and the depth is 10–12 m.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention provides a method for graded control and uniform pressure relief in high-stress hazardous areas of wide coal pillars, which has significant beneficial effects:

[0025] 1. Precise graded control: Through numerical simulation or mechanical calculation, high stress concentration areas (stress > 2.0σ0), general stress concentration areas (1.5σ0 < stress ≤ 2.0σ0), disturbed stress areas (1.0σ0 < stress ≤ 1.5σ0), and low stress areas (stress < 1.0σ0) are divided to achieve precise identification of stress distribution in wide coal pillars, and targeted decompression parameters are formulated to avoid insufficient or excessive decompression in some areas.

[0026] 2. Uniform pressure relief effect: By adopting the through-layer drilling hydraulic cutting technology, the drilling spacing (5×5m to 10×10m) and slot spacing (2m to 4m) and other parameters are optimized according to the stress level to form uniform slots, effectively releasing high stress and reducing the risk of secondary stress concentration.

[0027] 3. Enhanced safety: By monitoring the energy index Q (Qmax, Qtotal < 104 J, Qtotal < 1.2 times the initial stress zone index) and the drill cuttings index S (critical value 2.5~3.5 kg / m) of microseismic monitoring, the pressure relief effect can be evaluated in real time, and large-diameter boreholes (94~133 mm) or pre-splitting blasting measures can be added in a timely manner to ensure the safety of coal roadway excavation and mining.

[0028] 4. High adaptability: In view of the complex stress distribution of wide coal pillars, the method can flexibly adjust parameters, making it suitable for different geological conditions and significantly reducing the risk of dynamic disasters.

[0029] This method achieves uniform stress release in wide coal pillar areas through graded control and precise pressure relief, ensuring safe production and combining high efficiency with practicality.

[0030] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is a schematic diagram of a method for graded control and uniform pressure relief in high-stress dangerous areas of wide coal pillars according to the present invention.

[0033] Figure labels: 1. Wide coal pillar; 2. Vertical stress distribution curve of coal seam; 3. Bottom roadway; 4. Cross-layer borehole; 5. Slot; 6. Stress unloading line. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0037] Please see Figure 1 This is a method for graded control and uniform pressure relief in high-stress dangerous areas of wide coal pillars, comprising the following steps:

[0038] (1) Classify the risk area of ​​wide coal pillar 1: Determine the vertical stress distribution in the wide coal pillar area through numerical simulation or mechanical calculation methods, such as... Figure 1 The vertical stress distribution curve of the coal seam is shown in Figure 2. Based on the degree of stress concentration, the risk area is divided into a high stress concentration area, a general stress concentration area, an initial stress area, and a low stress area.

[0039] (2) Divide and manage risk areas of different levels: Determine the hydraulic slotting borehole layout parameters of the corresponding areas according to the stress level of the risk areas, including borehole spacing, coal section slotting spacing, single-blade slotting time and single-blade coal cutting amount.

[0040] (3) Drill through-layer boreholes 4 in the bottom roadway 3 to risk areas with different stress levels, and perform hydraulic cutting operations on the through-layer boreholes to form slots 5; according to the different risk areas delineated in step (1) and the hydraulic cutting parameters determined in step (2), perform hydraulic cutting pressure relief and permeability enhancement operations on coal bodies with different stress levels in the wide coal pillar area to form Figure 1 Stress unloading line 6 after the coal seam is cut.

[0041] (4) Monitor the energy level during the hydraulic slit depressurization process and evaluate the depressurization effect based on the energy index;

[0042] (5) During the excavation of coal roadways or the mining of working faces, the drill cuttings quantity index S is used to predict the local pressure relief effect. When the drill cuttings quantity index S exceeds the critical value, local pressure relief measures are taken.

[0043] (6) After taking local pressure relief measures, when the drill cuttings volume index S is lower than the critical value, the next round of coal roadway excavation or working face mining operation shall be carried out.

[0044] Further, in step (1), the stress in the high stress concentration zone is greater than 2.0σ0, the stress in the general stress concentration zone is between 1.5σ0 and 2.0σ0, the stress in the disturbed stress zone is between 1.0σ0 and 1.5σ0, and the stress in the low stress zone is less than 1.0σ0, where σ0 is the original stress value of the coal seam.

[0045] Furthermore, in step (2), for high stress concentration areas, the spacing of hydraulic slit boreholes is 5×5 meters, the spacing of the slots formed by the slits in the coal borehole section is 2 meters, the single-blade slit cutting time is 15 to 20 minutes, and the single-blade coal cutting amount is 0.5 to 0.6 tons.

[0046] Furthermore, in step (2), for general stress concentration areas, the spacing of hydraulic slit boreholes is 6-8 meters × 6-8 meters, the spacing of the slots formed by the slits in the coal borehole section is 2-3 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.4-0.5 tons.

[0047] Furthermore, in step (2), for the initial stress zone, the spacing of the hydraulic slit boreholes is 8-10 meters × 8-10 meters, the spacing of the slots formed by the slits in the coal borehole section is 3-4 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.3-0.4 tons.

[0048] Furthermore, in step (3), an ultra-high pressure hydraulic slitting device is used to perform hydraulic slitting operations for drilling through layers, and a backward slitting method is adopted.

[0049] Furthermore, in step (4), microseismic monitoring technology is used to monitor the energy level during the hydraulic slit depressurization process, and the energy index Q of microseismic monitoring is used to evaluate the depressurization effect. The energy index Q after hydraulic slit operation in the initial stress zone is used as the basis for the evaluation. 初 Based on this, the maximum energy Q of a single microseismic monitoring in a high stress concentration area is... 高max Total energy Q 高总 All below 10 4 J, and the total daily energy Q 高日总 When the stress level is less than 1.2 times the corresponding index of the initial stress zone, it is considered that the pressure relief is effective.

[0050] Otherwise, hydraulic slit cutting measures should be added to the corresponding area until the corresponding area meets the requirements for effective pressure relief.

[0051] Furthermore, in step (5), the predicted borehole depth for the drill cuttings quantity index S is 10 to 12 meters, and the critical values ​​for drill cuttings quantity in the ranges of 1 to 4 meters, 4 to 8 meters, and 8 to 12 meters are 2.5 kg / m, 2.8 kg / m, and 3.5 kg / m, respectively. When the drill cuttings quantity index S exceeds the critical value, large-diameter in-seam drilling or pre-splitting blasting technology is adopted for local pressure relief.

[0052] Furthermore, the diameter of the large-diameter in-seam borehole is 94–133 mm, and the spacing is 3–5 m; the spacing of the boreholes in the pre-splitting blasting technology is 10–15 m, and the depth is 10–12 m.

[0053] It should be noted that for low-stress areas, since the stress is less than the original stress value of the coal seam, there is no need to depressurize them; in addition, for general stress concentration areas, hydraulic cutting can usually depressurize normally, so it is usually not necessary to monitor the energy level during the hydraulic cutting process to determine whether the depressurization was successful.

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0055] Example 1: Control and pressure relief of high-stress hazardous areas in wide coal pillars in a coal mine

[0056] This embodiment takes a wide coal pillar area in a coal mine as an example. The wide coal pillar is 40 meters wide, the coal seam is 3 meters thick, and the original stress σ0 of the coal seam is 15 MPa. Through numerical simulation and mechanical calculation analysis, the vertical stress distribution in the wide coal pillar area is determined. Based on the degree of stress concentration, the risk areas of the wide coal pillar are divided into the following four categories:

[0057] High stress concentration area: stress greater than 30 MPa (i.e., 2.0σ0);

[0058] Typical stress concentration areas: stress between 22.5 MPa and 30 MPa;

[0059] Disturbance stress zone: stress between 15 MPa and 22.5 MPa;

[0060] Low-stress zone: stress less than 15 MPa.

[0061] Based on the stress level of different areas, the hydraulic slotting borehole layout parameters are determined as follows:

[0062] High stress concentration zone: The borehole spacing is 5×5 meters, the coal section slit spacing is 2 meters, the single-blade slit cutting time is 18 minutes, and the single-blade coal cutting amount is 0.55 tons;

[0063] In general stress concentration areas: the borehole spacing is 7×7 meters, the coal section cutting spacing is 2.5 meters, the single-blade cutting time is 12 minutes, and the single-blade coal cutting amount is 0.45 tons.

[0064] Initial stress zone: The borehole spacing is 9×9 meters, the coal section slit spacing is 3.5 meters, the single-blade slit cutting time is 10 minutes, and the single-blade coal cutting amount is 0.35 tons.

[0065] In the bottom slab tunnel, cross-layer drilling is carried out. Ultra-high pressure hydraulic slotting equipment is used for hydraulic slotting operations in the cross-layer drilling, employing a backward slotting method, cutting from the bottom of the hole towards the opening to form a slot. During the slotting process, the above parameters are strictly followed to ensure the slotting effect.

[0066] During the hydraulic slit depressurization process, microseismic monitoring technology was used to monitor the energy levels. Monitoring results showed that the total daily energy Q after the hydraulic slit operation in the initial stress zone... 初日总 The maximum energy Q of a single microseismic monitoring event is 5500 J in a high stress concentration area. 高max The total energy is 4000 J, and the total energy is Q. 高总 The total daily energy is 9000J, Q. 高日总 The value is 6000J. These indicators are all below 10⁴ J, and Q... 高日总 Less than 1.2×Q 初日总 (6600J) indicates that the pressure relief effect is effective.

[0067] During coal roadway excavation, the drill cuttings volume index S was used to predict the effect of local pressure relief. The predicted borehole depth was 11 meters. Drill cuttings volumes were measured in the ranges of 1–4 meters, 4–8 meters, and 8–12 meters, with results of 2.0 kg / m, 2.5 kg / m, and 3.0 kg / m, respectively. These values ​​were all below the critical values ​​of 2.5 kg / m, 2.8 kg / m, and 3.5 kg / m, respectively. Therefore, no local pressure relief measures were required.

[0068] Through the above steps, uniform pressure relief was achieved in the wide coal pillar area, ensuring the safe progress of coal roadway excavation.

[0069] Example 2: Control and pressure relief of high-stress hazardous areas in wide coal pillars of a coal mine

[0070] This embodiment takes a wide coal pillar area in another coal mine as an example. The wide coal pillar is 50 meters wide, the coal seam is 4 meters thick, and the original stress σ0 of the coal seam is 16.5 MPa. The vertical stress distribution in the wide coal pillar area is determined using mechanical calculation methods. Based on the degree of stress concentration, the risk areas are divided into the following four categories:

[0071] High stress concentration area: stress greater than 33 MPa (i.e. 2.0σ0);

[0072] Typical stress concentration areas: stress between 24.75 MPa and 33 MPa;

[0073] Disturbance stress zone: stress between 16.5 MPa and 24.75 MPa;

[0074] Low-stress zone: stress less than 16.5 MPa.

[0075] Based on the stress level of different areas, the hydraulic slotting borehole layout parameters are determined as follows:

[0076] High stress concentration zone: The borehole spacing is 5×5 meters, the coal section slit spacing is 2 meters, the single-blade slit cutting time is 20 minutes, and the single-blade coal cutting amount is 0.6 tons;

[0077] In general stress concentration areas: the borehole spacing is 8×8 meters, the coal section slit spacing is 3 meters, the single-blade slit cutting time is 15 minutes, and the single-blade coal cutting amount is 0.5 tons.

[0078] Initial stress zone: The borehole spacing is 10×10 meters, the coal section slit spacing is 4 meters, the single-blade slit cutting time is 12 minutes, and the single-blade coal cutting amount is 0.4 tons.

[0079] In the bottom slab tunnel, drilling is carried out across the layers. Ultra-high pressure hydraulic slotting equipment is used to perform hydraulic slotting operations for the cross-layer drilling, and a backward slotting method is adopted to form a slot.

[0080] During the hydraulic slit depressurization process, microseismic monitoring technology was used to monitor the energy levels. Monitoring results showed that the total daily energy Q after the hydraulic slit operation in the initial stress zone... 初日总 The maximum energy Q of a single microseismic monitoring event is 6000 J. In areas of high stress concentration, the maximum energy Q of a single microseismic event is... 高max The total energy is 9500 J, and the total energy is Q. 高总 The total daily energy is 1.2 × 10⁴ J, Q. 高日总The pressure relief effect was 7500 J. Since the total Qhigh exceeded 104 J, and the daily total Qhigh exceeded 1.2 × Qinitial (i.e., 7200 J), the pressure relief effect did not meet the standard. Therefore, hydraulic slit cutting measures were implemented in the high stress concentration area, adjusting the slit parameters and increasing the slit density until the monitoring indicators met the requirements.

[0081] During the longwall mining phase, the drill cuttings volume index S was used to predict the local pressure relief effect. The predicted borehole depth was 12 meters. Drill cuttings volumes were measured at depths of 1–4 meters, 4–8 meters, and 8–12 meters, with results of 2.6 kg / m, 2.9 kg / m, and 3.6 kg / m, respectively, exceeding the critical values ​​of 2.5 kg / m, 2.8 kg / m, and 3.5 kg / m. Therefore, large-diameter in-seam boreholes were used for local pressure relief, with a borehole diameter of 113 mm and a spacing of 4 meters. After pressure relief, drill cuttings volumes were measured again, with results of 2.2 kg / m, 2.5 kg / m, and 3.2 kg / m, respectively, below the critical values, allowing for the next round of longwall mining.

[0082] Through the above steps, uniform pressure relief was achieved in the wide coal pillar area, ensuring the safe operation of the working face mining.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for graded control and uniform pressure relief in high-stress hazardous areas of wide coal pillars, characterized in that, Includes the following steps: (1) Classify the risk areas of wide coal pillars: Determine the vertical stress distribution of the wide coal pillar area through numerical simulation or mechanical calculation methods, and classify the risk areas into high stress concentration areas, general stress concentration areas, initial stress areas and low stress areas according to the degree of stress concentration. (2) Divide and manage risk areas of different levels: Determine the hydraulic slotting borehole layout parameters of the corresponding areas according to the stress level of the risk areas, including borehole spacing, coal section slotting spacing, single-blade slotting time and single-blade coal cutting amount. (3) Drill through layers in the bottom slab tunnel to risk areas with different stress levels, and perform hydraulic cutting operations to form grooves in the through-layer drilling. (4) Monitor the energy level during the hydraulic slit depressurization process and evaluate the depressurization effect based on the energy index; (5) During the excavation of coal roadways or the mining of working faces, the drill cuttings quantity index S is used to predict the local pressure relief effect. When the drill cuttings quantity index S exceeds the critical value, local pressure relief measures are taken. (6) After taking local pressure relief measures, when the drill cuttings volume index S is lower than the critical value, the next round of coal roadway excavation or working face mining operation shall be carried out.

2. The method according to claim 1, characterized in that, In step (1), the stress in the high stress concentration zone is greater than 2.0σ0, the stress in the general stress concentration zone is between 1.5σ0 and 2.0σ0, the stress in the disturbance stress zone is between 1.0σ0 and 1.5σ0, and the stress in the low stress zone is less than 1.0σ0. σ0 is the original stress value of the coal seam.

3. The method according to claim 1, characterized in that, In step (2), for high stress concentration areas, the spacing of hydraulic slit boreholes is 5×5 meters, the spacing of the slots formed by the slits in the coal borehole section is 2 meters, the single-blade slit cutting time is 15 to 20 minutes, and the single-blade coal cutting amount is 0.5 to 0.6 tons.

4. The method according to claim 1, characterized in that, In step (2), for general stress concentration areas, the spacing of hydraulic slit boreholes is 6-8 meters × 6-8 meters, the spacing of the slots formed by the slits in the coal borehole section is 2-3 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.4-0.5 tons.

5. The method according to claim 1, characterized in that, In step (2), for the disturbed stress zone, the spacing of the hydraulic slit boreholes is 8-10 meters × 8-10 meters, the spacing of the slots formed by the slits in the coal borehole section is 3-4 meters, the single-blade slit cutting time is 10-15 minutes, and the single-blade coal cutting amount is 0.3-0.4 tons.

6. The method according to claim 1, characterized in that, In step (3), an ultra-high pressure hydraulic slitting device is used to perform hydraulic slitting operations for drilling through layers, and a backward slitting method is adopted.

7. The method according to claim 1, characterized in that, In step (4), microseismic monitoring technology is used to monitor the energy level during the hydraulic slit depressurization process, and the energy index Q of microseismic monitoring is used to evaluate the depressurization effect. The energy index Q after hydraulic slit operation in the initial stress zone is used as the basis for the evaluation. 初 Based on this, the maximum energy Q of a single microseismic monitoring in a high stress concentration area is... 高max Total energy Q 高总 All below 10 4 J, and the total daily energy Q 高日总 When the stress level is less than 1.2 times the corresponding index of the initial stress zone, it is considered that the pressure relief is effective. Otherwise, hydraulic slit cutting measures should be added to the corresponding area until the corresponding area meets the requirements for effective pressure relief.

8. The method according to claim 1, characterized in that, In step (5), the predicted borehole depth for the drill cuttings quantity index S is 10 to 12 meters. The critical values ​​for drill cuttings quantity in the ranges of 1 to 4 meters, 4 to 8 meters, and 8 to 12 meters are 2.5 kg / m, 2.8 kg / m, and 3.5 kg / m, respectively. When the drill cuttings quantity index S exceeds the critical value, large-diameter in-seam drilling or pre-splitting blasting technology is adopted for local pressure relief.

9. The method according to claim 8, characterized in that, The diameter of the large-diameter in-seam borehole is 94–133 mm, and the spacing is 3–5 m; the spacing of the boreholes in the pre-splitting blasting technology is 10–15 m, and the depth is 10–12 m.

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