Working face roof advanced pressure relief dense hole arrangement parameter design method

Abstract

The invention relates to the technical field of roof cutting pressure relief gob-side entry retaining, in particular to a working face roof advanced pressure relief dense hole arrangement parameter design method which comprises the steps that S1, based on dense hole rock macroscopic stress analysis, a calculation relation between dense hole rock macroscopic stress and dense hole plastic zone development radius is established; step S2A, selecting a strength criterion, calculating a dense hole plastic zone development radius, and determining dense hole arrangement spacing; step S2B, based on dense inter-hole rock infinitesimal body stress analysis, establishing a dense inter-hole rock infinitesimal body mechanical equilibrium equation, and in combination with a Mohr-Coulomb strength criterion, establishing a calculation relationship between dense inter-hole rock infinitesimal body stress and an advanced working face distance; and S3, selecting according to a strength criterion, correspondingly establishing an equivalent relationship between the macroscopic stress of the rock among the dense holes and the stress of the infinitesimal body of the rock among the dense holes, forming a calculation relationship between the advance working face distance and the development radius of the plastic zone of the dense holes, and quickly determining the arrangement parameters of the dense holes.

Description

Technical Field

[0001] This application relates to the field of cutting off the top and releasing pressure along the goaf, and in particular to a design method for the arrangement parameters of dense holes for advance pressure relief on the working face roof. Background Technology

[0002] The technology of cutting the roof and leaving the roadway along the goaf is to cut off the stress transmission of the roadway roof, increase the collapse height of the roof in the goaf, and make fuller filling of the goaf by utilizing the crushing and swelling properties of the collapsed gangue. This can reduce the pressure of the roadway along the goaf, reduce energy events during mining, reduce the probability of rock bursts, and thus retain the roadway along the goaf for the next working face to be mined.

[0003] To cut off the roof of roadways, pre-splitting blasting technology was previously used in field practice to achieve roof cutting and pressure relief. However, underground blasting not only disturbs the surrounding rock and affects its stability, but also produces harmful gases. For the safety of underground workers, many coal mines have adopted dense-hole drilling to replace blasting for roof cutting and pressure relief in recent years. However, due to a lack of theoretical knowledge and experience, the design of dense-hole layout schemes has been hampered by insufficient consideration of key layout parameters. For example, with the same hole diameter, too small a hole spacing will cause the roof damage area to extend into the roadway, while too large a hole spacing will affect the pressure relief effect; if the distance between the dense-hole layout and the working face is too small, the dense-holes will be located in the roof pressure reduction zone, resulting in insufficient pressure relief. All of these problems can lead to roof safety issues in the roadway.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this application is to provide a method for designing the arrangement parameters of densely packed pre-decompression holes on the top plate of a working face, so as to solve or alleviate the problems existing in the prior art.

[0006] To achieve the above objectives, this application provides the following technical solution: This application provides a method for designing the layout parameters of densely packed holes for pre-decompression stress relief on the top plate of a working face. The layout parameters include the spacing between the densely packed holes. Advanced working face distance ; The design method for the arrangement parameters includes: Step S1: Based on the macroscopic stress analysis of rocks with dense pores, establish the relationship between the macroscopic stress of rocks with dense pores and the development radius of the plastic zone with dense pores. Calculate the relational expression; Step S2A: Select the strength criterion and calculate the development radius of the densely porous plastic zone. Determine the spacing of the densely packed holes. Densely spaced holes satisfy: ; Step S2B: Based on the stress analysis of the rock micro-element with dense pores, establish the mechanical equilibrium equation of the rock micro-element with dense pores, and combine it with the Mohr-Coulomb strength criterion to establish the relationship between the stress on the rock micro-element with dense pores and the distance to the advanced working face. Inter-calculation relationship; Step S3: Based on the different strength criteria selected in step S2A, establish the equivalent relationship between the macroscopic stress of the rock between dense pores and the micro-element stress of the rock between dense pores, thereby forming the advance working face distance. Radius of the densely pored plastic zone The calculation formula.

[0007] Preferably, In step S2A, the strength criterion is selected as the Hawke-Brown strength criterion.

[0008] Preferably, Step S2B further includes: establishing the reduced strength of the rock based on the Mohr-Coulomb strength criterion. Calculation formula; Step S3 specifically involves: rock reduction strength. equal to the horizontal stress in front of the working face The formula for calculating the reduced strength of rocks, the macroscopic stress of rocks between densely porous areas and the development radius of the plastic zone of densely porous areas. Calculation formulas, stress on rock micro-elements between dense pores and distance from the working face Calculate the relationship between the time intervals and establish the distance to the working face. Radius of the densely pored plastic zone The calculation formula.

[0009] Preferably, in step S1, The macroscopic stress of the rock between dense pores and the development radius of the plastic zone of dense pores The calculation formula is: ; in: The radius of the densely packed holes is in mm; The radius of the densely porous plastic zone is shown in mm. The horizontal stress around the densely packed holes is measured in MPa. The stress at the stress analysis point in the middle of the densely packed holes is horizontal, measured in MPa. The stress at the midpoint of the densely packed holes tends to be horizontal, MPa; The friction angle of the rock mass surrounding the dense pores is °.

[0010] Preferably, in step S2A, the Hawke-Brown strength criterion formula is: ; in: The uniaxial compressive strength of the rock is given in MPa. All are Hawkebrung empirical coefficients.

[0011] Preferably, in step S2B, The mechanical equilibrium equation of the rock micro-element with dense pores is: ; The stress on the densely porous rock micro-elements and the distance to the advanced working face The calculation relationship is as follows: ; in, Where is the coal seam thickness, in meters (m). Cohesion, MPa; The horizontal stress in front of the working face, MPa; The vertical stress in front of the working face is expressed in MPa.

[0012] Preferably, in step S2B, The rock reduced strength The calculation formula is: ; in, denoted as rock reduced strength, MPa.

[0013] Preferably, in step S3, The distance of the advanced working surface Radius of the densely pored plastic zone The calculation formula is as follows: ; Among them, when When taking the peak value, Minimum advance working surface distance , .

[0014] Preferably, the arrangement parameters further include the dense hole drilling height. The height of the dense hole drilling satisfy: ; in, The height of the dense hole drilling is in meters (m). The working face mining height is in meters (m). The value is the amount of roof settlement, expressed in meters (m). The volume of the bottom drum is in meters (m). This is the coefficient of fragmentation.

[0015] Compared with the closest prior art, the technical solution of this application has the following beneficial effects: Based on the analysis of macroscopic stress and micro-element stress of rock between dense holes, this application establishes a rapid method for determining the parameters of dense hole arrangement. By combining the consideration of rock limit equilibrium state, the design of dense hole arrangement parameters is made more reasonable, which improves the decompression effect on the roadway roof while ensuring the safety of the surrounding rock of the roadway. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein: Figure 1 This is a schematic diagram of the development range of the densely porous plastic zone according to some embodiments of this application; Figure 2 This is a schematic diagram of the vertical stress distribution in front of the working face and the distance between the dense holes and the working face according to some embodiments of this application; Figure 3 This is a schematic diagram of the drilling height for dense holes provided according to some embodiments of this application.

[0017] Explanation of reference numerals in the attached figures: 1. Dense holes; 2. Coal seam; 3. Working face; 4. Vertical stress distribution curve; 5. Roadway. Detailed Implementation

[0018] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0019] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0021] In the description of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require that this application be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. The terms "connected," "linked," and "set up" used in this application should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; direct connections or indirect connections through intermediate components; wired connections, radio connections, or wireless communication signal connections. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0022] The following is in conjunction with the appendix Figure 1-3 This application provides a more detailed description of the design method for the arrangement parameters of the pre-decompression dense holes 1 on the top plate of the working face 3.

[0023] A method for designing the arrangement parameters of the pre-pressure relief dense holes 1 on the top plate of working face 3, wherein the arrangement parameters include the arrangement spacing of the dense holes 1. 3-meter distance from the advanced working face ; The design methods for layout parameters include: Step S1: Based on the macroscopic stress analysis of the rock between dense pores 1, establish the relationship between the macroscopic stress of the rock between dense pores 1 and the development radius of the plastic zone of dense pores 1. Calculate the relational expression; Step S2A: Select the strength criterion and calculate the development radius of the plastic zone of dense pores 1. Determine the spacing of the densely packed holes 1 Densely spaced holes 1 satisfy: ; Step S2B: Based on the stress analysis of the rock micro-element in the dense pore 1 space, establish the mechanical equilibrium equation of the rock micro-element in the dense pore 1 space, and combine it with the Mohr-Coulomb strength criterion to establish the relationship between the stress on the rock micro-element in the dense pore 1 space and the distance to the advanced working face 3. Inter-calculation relationship; Step S3: Based on the different strength criteria selected in step S2A, establish the equivalent relationship between the macroscopic stress of the rock between dense pores 1 and the micro-element stress of the rock between dense pores 1, thereby forming the distance of the advanced working face 3. With the development radius of the plastic zone of dense pores 1 The calculation formula.

[0024] In a specific embodiment of this application, in step S1, geophysical exploration technology is used to obtain the burial depth of the roof of roadway 5, and hollow inclusion technology is used to obtain the vertical stress and horizontal stress distribution data of the roof of roadway 5. The vertical stress of the roof of roadway 5 is caused by the redistribution of stress in the surrounding rock in front of the working face 3 due to the mining of coal seam 2. However, since the dense holes 1 are arranged on the surface of the roof of roadway 5, and the area around the dense holes 1 is not subjected to the supporting force from inside roadway 5, the force cannot exist alone. Therefore, when analyzing the macroscopic stress of the rock between the dense holes 1, it is assumed that the rock mass around the dense holes 1 is not subjected to the vertical force, and only the horizontal stress around the dense holes 1 is considered. Function: Dense holes 1 cause damage to the integrity of the roof of roadway 5 through a damage effect. After the dense holes 1 are drilled into the roof of roadway 5, the pressure around the dense holes 1 causes the development of plastic zones around them. When the plastic zones between the dense holes 1 become connected, the roof strength at the location of the dense holes 1 is reduced, which is considered as damage to the roof between the dense holes 1, producing a pressure relief effect. Accordingly, the optimal spacing of the dense holes 1 is determined. The development radius of the plastic zone is twice that of the dense pores. That is, in step S2A, the spacing of the dense holes 1 is... satisfy: When designing actual parameters, the spacing of the densely packed holes 1 is... No more than twice the development radius of the dense pore 1 plastic zone At all times, it can be ensured that the rock in the densely packed pores is in a plastic state; In step S2B, stress analysis is performed on the rock micro-elements between the densely packed holes 1, based on the overall stress situation of the tunnel 5. At this time, the vertical stress in front of the working face 3 is... and horizontal stress in front of working face 3 Simultaneously acting on the interior of the surrounding rock of tunnel 5, these forces must be considered together when calculating the stress on the rock micro-elements between the densely packed holes 1. Since the densely packed holes 1 have a relatively small impact on the stress distribution of the rock micro-elements, they can be regarded as a homogeneous continuous body. Therefore, an arbitrary rock micro-element can be selected in front of working face 3 for stress analysis. After establishing the mechanical equilibrium equation, and combining it with the Mohr-Coulomb strength criterion, the stress on the rock micro-elements between the densely packed holes 1 and the distance from the working face 3 under the limit equilibrium state can be obtained. Inter-calculation relationship; In step S2A, the strength criteria include the Mohr-Coulomb strength criterion and the Hawke-Brown strength criterion. When the Mohr-Coulomb strength criterion is selected, in step S3, the horizontal stress around the dense hole 1 is... Equal to the horizontal stress in front of working face 3 When the Hawkebrung strength criterion is selected, in step S3, the reduced strength of the rock is... Equal to the horizontal stress in front of working face 3 And combined with the macroscopic stress of the rock between dense pores 1 established in step S1 and the development radius of the plastic zone of dense pores 1 Calculate the relationship between the forces acting on the rock micro-element within the densely packed pore 1 and the distance from the advanced working face 3. The calculation formula is used to form a 3-distance advance working face. With the development radius of the plastic zone of dense pores 1 The first calculation formula is used to determine the development radius of the plastic zone with dense pores 1. Based on this, the development radius of the plastic zone of dense pores is achieved. Quick determination; Steps S2A and S2B can be executed in parallel or sequentially, and there is no requirement for a specific execution order.

[0025] Because the top rock experiences strength reduction under the action of the dense holes 1, in order to more accurately reflect the actual strength of the rock, the strength criterion in step S2A is selected as the Hawke-Brown strength criterion.

[0026] To obtain the optimal arrangement parameters, it is considered that the rock between the densely packed holes 1 is in a state of limit equilibrium, that is, when the spacing of the densely packed holes 1 is... Equal to twice the development radius of the dense pore 1 plastic zone At that time, the rock blocks in the densely packed pores were all in the critical state of elastic-plasticity. Therefore, step S2B also includes: establishing the reduced strength of the rock based on the Mohr-Coulomb strength criterion. Calculation formula; Step S3 specifically involves: rock reduction strength. Equal to the horizontal stress in front of working face 3 The formula for calculating the reduced strength of rocks, the macroscopic stress of rocks in densely porous pore 1 and the development radius of the plastic zone in densely porous pore 1. Calculation formulas, stress on rock micro-elements between dense pores 1 and distance from the advanced working face 3 Calculate the relationship between the distances and establish the three distances of the advanced working face. With the development radius of the plastic zone of dense pores 1 The calculation formula.

[0027] In step S1, Macroscopic stress of rocks in densely porous pore 1 and the development radius of the plastic zone in densely porous pore 1 The calculation formula is: (1); in: The radius of the densely packed holes is 1 mm; The radius of development of the plastic zone with dense pores is shown in mm. The horizontal stress around the densely packed holes 1 is MPa; The stress at the stress analysis point in the middle of the densely packed holes is horizontal, measured in MPa. The stress analysis point in the middle of the densely packed holes tends to be horizontal, with a stress level of MPa. The friction angle of the rock mass surrounding Dense Hole 1 is °.

[0028] In a specific embodiment of this application, as described above, only the horizontal stress around the densely packed holes 1 is considered here. In two-dimensional polar coordinates, the stress components at the stress analysis point in the middle of the dense borehole 1 are shown in formula (1); the friction angle of the rock mass surrounding the dense borehole 1. The radius of the dense pore 1 was measured through rock mechanics experiments. Select directly based on the on-site situation.

[0029] In step S2A, the Hawke-Brown strength criterion formula is: (2); in: The uniaxial compressive strength of the rock is given in MPa. All are Hawkebrung empirical coefficients.

[0030] In a specific embodiment of this application, the roof of roadway 5 dips to both sides of coal seam 2, and the horizontal stress is concentrated on the sides. Since there is no stress concentration in the strike direction due to the excavation of roadway 5, the horizontal stress in the dip direction is greater than the horizontal stress in the strike direction. Correspondingly, in the Hawke-Brown strength criterion formula, the stress analysis point in the middle of the densely packed boreholes 1 has a horizontal stress in the dip direction. The stress at the midpoint of the densely packed holes 1 represents the maximum principal stress, indicating a horizontal stress distribution. Minimum principal stress; uniaxial compressive strength of rock The results were obtained through indoor experiments using a uniaxial compression testing instrument; the Hawke-Brown empirical coefficients were obtained by looking up tables.

[0031] Combining formulas (1) and (2), the radius of the densely packed holes 1 can be obtained. With the development radius of the plastic zone of dense pores 1 Calculation formula: (3); The development radius of the plastic zone at the dense pore 1 can then be calculated. .

[0032] In step S2B, The mechanical equilibrium equation of the rock micro-element in the densely pored space is: (4); The stress on the rock micro-element in the densely pored 1-hole space and the distance to the advanced working face 3 The calculation relationship is as follows: (5); in, The thickness of coal seam 2 is in meters. Cohesion, MPa; The horizontal stress in front of working face 3 is MPa; The vertical stress in front of working face 3 is MPa.

[0033] In a specific embodiment of this application, cohesion The thickness of coal seam 2 was measured through rock mechanics experiments. Obtained through well logging data; According to the Mohr-Coulomb strength criterion, under the limit equilibrium stress state, the vertical stress in front of working face 3 is... satisfy: (6); Combining formulas (4) and (6), we obtain formula (5).

[0034] In step S2B, Rock reduction strength The calculation formula is: (7); in, denoted as rock reduced strength, MPa.

[0035] In a specific embodiment of this application, the strength of the pre-cracked rock block in the dense hole 1 after reduction is calculated using formula (7). In order to obtain the optimal arrangement parameters, considering that the rock block here is in the critical state of elastic-plasticity, the Mohr-Coulomb strength criterion is used for calculation.

[0036] In step S3, Advanced working face 3 distance With the development radius of the plastic zone of dense pores 1 The calculation formula is as follows: (8); Among them, when When taking the peak value, Minimum advance working face distance 3 , .

[0037] In a specific embodiment of this application, the vertical stress in front of the working surface 3 The pressure distribution curve 4 is obtained through on-site pressure testing of the support structure. To ensure the pre-pressure relief effect of the dense holes 1, the maximum vertical stress in front of the working face 3 is first measured. Determine the minimum advance working face distance 3 Then set the advance working surface distance 3. That is, the furthest position of the dense holes 1 is at least ahead of the working face 3. .

[0038] The layout parameters also include the drilling height of the dense hole 1. Drilling height of dense holes 1 satisfy: (9); in, Drilling height for dense hole 1, in meters; The mining height of working face 3 is in meters. The value is the amount of roof settlement, expressed in meters (m). The volume of the bottom drum is in meters (m). This is the coefficient of fragmentation.

[0039] In a specific embodiment of this application, the falling and fracturing of the roof rock mass exhibits a fragmentation and expansion characteristic, meaning that the volume of the fractured rock mass will be larger than its original state. The height of the roof pre-splitting boreholes must be sufficient to ensure that the fragmentation and expansion of the felled roof rock can fill the goaf, preventing the old roof from fracturing along its strike and dip, thereby reducing or eliminating the impact of the periodic pressure of the old roof on the stability of roadway 5; the depth of the dense borehole 1 can be calculated by combining the borehole height of the dense borehole 1 with the borehole angle. The selection is made during the design of working face 3, and is generally based on the thickness of coal seam 2. and This was obtained through collecting and analyzing mine pressure patterns and data. The coefficient of rupture of the roof lithology can be obtained through indoor experimental research by conducting crushed stone compression tests using a uniaxial experimental instrument.

[0040] Shenyang Coking Coal Co., Ltd.'s Hongyang No. 3 Mine adopted a dense borehole 1 decompression and goaf retention scheme for on-site roadway retention. The layout parameters of the dense borehole 1 were designed using this scheme. By substituting on-site data, when the borehole diameter was 42mm and 50mm, the suitable spacing of the dense borehole 1 was calculated to be 182.3mm and 258.4mm, respectively. Furthermore, the construction of the dense borehole 1 at Hongyang No. 3 Mine needed to advance the working face by at least 313.71m and 14.63m, respectively, and the drilling depth of the dense borehole 1 should not be less than 8.84m. The final design adopted a 50mm borehole diameter, corresponding to a spacing of 250mm, with the furthest placement of the dense borehole 1 always advancing the working face by 315m, and a drilling depth of 9m. On-site application showed good roadway retention effect and a good decompression effect on the roof of roadway 5.

[0041] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for designing the arrangement parameters of densely packed pre-pressure relief holes on the top plate of a working face, characterized in that, The arrangement parameters include the spacing of the densely packed holes. Advanced working face distance ; The design method for the arrangement parameters includes: Step S1: Based on the macroscopic stress analysis of rocks with dense pores, establish the relationship between the macroscopic stress of rocks with dense pores and the development radius of the plastic zone with dense pores. Calculate the relational expression; Step S2A: Select the strength criterion and calculate the development radius of the densely porous plastic zone. Determine the spacing of the densely packed holes. Densely spaced holes satisfy: ; Step S2B: Based on the stress analysis of the rock micro-element with dense pores, establish the mechanical equilibrium equation of the rock micro-element with dense pores, and combine it with the Mohr-Coulomb strength criterion to establish the relationship between the stress on the rock micro-element with dense pores and the distance to the advanced working face. Inter-calculation relationship; Step S3: Based on the different strength criteria selected in step S2A, establish the equivalent relationship between the macroscopic stress of the rock between dense pores and the micro-element stress of the rock between dense pores, thereby forming the advance working face distance. Radius of the densely pored plastic zone The calculation formula.

2. The method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in claim 1, characterized in that, In step S2A, the strength criterion is selected as the Hawke-Brown strength criterion.

3. The method for designing the arrangement parameters of densely packed pre-pressure relief holes on the top plate of a working face as described in claim 2, characterized in that, Step S2B further includes: establishing the reduced strength of the rock based on the Mohr-Coulomb strength criterion. Calculation formula; Step S3 specifically involves: rock reduction strength. equal to the horizontal stress in front of the working face The formula for calculating the reduced strength of rocks, the macroscopic stress of rocks between densely porous areas and the development radius of the plastic zone of densely porous areas. Calculation formulas, stress on rock micro-elements between dense pores and distance from the working face Calculate the relationship between the time intervals and establish the distance to the working face. Radius of the densely pored plastic zone The calculation formula.

4. The method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in claim 3, characterized in that, In step S1, The macroscopic stress of the rock between dense pores and the development radius of the plastic zone of dense pores The calculation formula is: ； in: The radius of the densely packed holes is in mm; The radius of the densely porous plastic zone is shown in mm. The horizontal stress around the densely packed holes is measured in MPa. The stress at the stress analysis point in the middle of the densely packed holes is horizontal, measured in MPa. The stress at the midpoint of the densely packed holes tends to be horizontal, at MPa.

5. The method for designing the arrangement parameters of the advanced pressure relief dense holes in the top plate of a working face as described in claim 4, characterized in that, In step S2A, the Hawke-Brown strength criterion formula is: ； in: The uniaxial compressive strength of the rock is given in MPa. All are Hawkebrung empirical coefficients.

6. The method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in claim 4, characterized in that, In step S2B, The mechanical equilibrium equation of the rock micro-element with dense pores is: ； The stress on the densely porous rock micro-elements and the distance to the advanced working face The calculation relationship is as follows: ； in, The coal seam thickness is in meters (m). Cohesion, MPa; The horizontal stress in front of the working face, MPa; The vertical stress in front of the working face, MPa; The friction angle of the rock mass surrounding the dense pores is °.

7. The method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in claim 6, characterized in that, In step S2B, The rock reduced strength The calculation formula is: ； in, denoted as rock reduced strength, MPa.

8. The method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in claim 7, characterized in that, In step S3, The distance of the advanced working surface Radius of the densely pored plastic zone The calculation formula is as follows: ； Among them, when When taking the peak value, Minimum advance working surface distance , .

9. A method for designing the arrangement parameters of advanced pressure relief dense holes in the top plate of a working face as described in any one of claims 1-8, characterized in that, The arrangement parameters also include the drilling height for dense holes. The height of the dense hole drilling satisfy: ； in, The height of the dense hole drilling is in meters (m). The working face mining height is in meters (m). The value is the amount of roof settlement, expressed in meters (m). The volume of the bottom drum is in meters (m). This is the coefficient of fragmentation.

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