Top plate segmented weakening method for preventing and treating rock burst

Abstract

The invention discloses a roof subsection weakening method for preventing and treating rock burst. The roof subsection weakening method comprises the steps that S1, basic parameters of a coal face are obtained; s2, based on the basic parameters of the coal face, dividing a top plate of the coal face into a plurality of independent weakening sections along the trend; s3, establishing a corresponding relation between the independent weakening section and the coal mining cutter number; s4, sequentially performing weakening treatment on each weakening section in the coal mining process according to the corresponding relationship; and S5, circularly executing the steps S3-S4 to form a stepped weighting mode in which coal mining and weakening are synchronously carried out. The technical problems that the engineering cost is high, the construction period is long, production interference is large, the roof still intensively releases high-strength energy in a short time, and the rock burst risk cannot be effectively avoided in an existing overall roof cutting pressure relief technology can be solved.

Description

Technical Field

[0001] This invention belongs to the field of coal mining and dynamic disaster prevention technology, and particularly relates to a method for segmented weakening of the roof for preventing rockburst. Background Technology

[0002] Rockburst is a violent dynamic destructive phenomenon caused by the instantaneous release of elastic strain energy of coal and rock mass during coal mining. It is often accompanied by coal and rock ejection, loud noises, and blast waves, and can cause casualties, equipment damage, and secondary disasters. Periodic pressure on the coal face, especially overall pressure, releases a large amount of energy in a short period of time, which is an important factor in inducing rockburst. Roof cutting and pressure relief is a common technique for rockburst prevention and control. By artificially weakening the roof and altering its fracture pattern, the risk of concentrated energy release can be reduced.

[0003] Existing roof-cutting and pressure-relief technologies typically focus on the overall or large-scale simultaneous weakening of the working face roof. While this overall roof-cutting method can achieve the pressure relief objective, it suffers from high engineering costs, long construction periods, and significant disruption to normal coal mining production. Furthermore, the overall roof-cutting results in a one-time release of roof energy; although weakened, the released dynamic energy level remains high, failing to fundamentally disperse the concentrated high-energy pressure into multiple, lower-energy, dispersed pressure events. Therefore, it falls short in terms of the precision and effectiveness of rockburst prevention. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a segmented weakening method for preventing rockbursts. This method aims to solve the technical problems of existing integral roof cutting and pressure relief technologies, such as high engineering costs, long construction periods, significant disruption to production, and the inability to effectively avoid the risk of rockbursts due to the roof still releasing high-intensity energy in a short period of time.

[0005] To achieve the above objectives, the present invention provides a method for segmented weakening of the roof for preventing rockbursts, comprising:

[0006] S1. Obtain basic parameters of the coal mining face;

[0007] S2. Based on the basic parameters of the coal mining face, the roof of the working face is divided into multiple independent weakened sections along the strike.

[0008] S3. Establish the correspondence between the independent weakened sections and the number of coal cutting tools;

[0009] S4. According to the aforementioned correspondence, each weakened section is sequentially weakened during the coal mining process;

[0010] S5. Repeat S3-S4 to form a stepped pressure mode in which coal mining and weakening are carried out simultaneously.

[0011] Optionally, the basic parameters of the coal mining face include: face length, periodic pressure step distance, coal mining machine cutting depth, basic roof thickness, and hydraulic support width.

[0012] Optionally, based on the basic parameters of the coal mining face, dividing the roof of the working face along the strike into multiple independent weakened sections includes:

[0013] A coordinate system along the working face is established based on each weakening length, wherein each weakening length is calculated from the working face length in the basic parameters of the coal mining face and the number of coal cutting tools during a cycle of pressure.

[0014] The working face top plate is divided into multiple independent weakened segments according to the coordinate system.

[0015] Optionally, the calculation steps for each weakening length include:

[0016] Based on the cycle pressing step distance and the coal mining machine cutting depth, calculate the number of cutting blades during one cycle pressing period;

[0017] The total number of independent weakened sections of the top plate is set to be numerically equal to the number of cutting blades during one cycle of pressing.

[0018] The length of each weakening segment is calculated based on the length of the working face and the total number of independent weakening segments of the top plate.

[0019] Optionally, establishing the correspondence between the independent weakened sections and the number of coal cutting tools includes:

[0020] The current cumulative number of coal cutters is determined based on the cumulative advance distance of the working face and the cutting depth of the coal mining machine.

[0021] Based on the current cumulative number of coal cutting blades and the total number of independent weakened sections of the roof, a model calculation is performed, and the weakened section number that should be weakened is determined according to the model calculation result.

[0022] Based on the weakened segment number, establish the correspondence between the independent weakened segment and the current cumulative number of coal cutting blades.

[0023] Optionally, according to the aforementioned correspondence, the weakening treatment of each weakened section during the coal mining process includes:

[0024] Based on the determined weakening section number, weakening operation points are arranged at the joints of adjacent hydraulic supports within the corresponding weakening section range.

[0025] The roof at the work site is weakened by at least one of the following methods: blasting weakening, hydraulic fracturing, or rock breaking with an expansive agent. The weakening treatment extends through the basic roof thickness.

[0026] Optionally, S3-S4 can be executed cyclically to form a stepped pressure-applying mode that simultaneously mines coal and weakens the soil, including:

[0027] Repeatedly execute the process of determining the current number of coal cutting tools, determining the current weakening section number, and implementing roof weakening to disperse roof fracture and energy release in time and space, thereby achieving step-by-step pressure.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) Reduce the risk of rockburst: The originally concentrated periodic rockburst is decomposed into multiple low-intensity stepped rockburst events, reducing the intensity of single energy release and effectively reducing the probability of rockburst.

[0030] (2) Reduce engineering costs: reduce the amount of work per project in stages, reduce the synchronization of operations with coal mining, avoid long-term shutdowns, and significantly reduce construction and time costs.

[0031] (3) Improve construction convenience: The weakening holes are arranged at the joint of the support, with a spacing equal to the width of the support, which facilitates construction positioning and does not affect the support function of the support. Attached Figure Description

[0032] 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. In the drawings:

[0033] Figure 1 This is a flowchart of a method for segmented weakening of the roof slab to prevent rockbursts, according to an embodiment of the present invention. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0036] This embodiment proposes a method for segmented weakening of the roof to prevent rockbursts, such as... Figure 1 As shown, the specific steps include:

[0037] S1. Obtain basic parameters of the coal mining face;

[0038] S2. Based on the basic parameters of the coal mining face, the roof of the working face is divided into multiple independent weakened sections along the strike.

[0039] S3. Establish the correspondence between the independent weakened sections and the number of coal cutting tools;

[0040] S4. According to the aforementioned correspondence, each weakened section is sequentially weakened during the coal mining process;

[0041] S5. Repeat S3-S4 to form a stepped pressure mode in which coal mining and weakening are carried out simultaneously.

[0042] Specifically, this method divides the working face roof into multiple independent weakening sections along the strike, establishing a correspondence between weakening sections and the number of coal cutting cutters, achieving a cyclical operation mode of "one cut of coal mining, one weakening section". Weakening operation points are located at the joints of the hydraulic supports, using methods such as hydraulic fracturing and blasting to penetrate the basic roof, thus dispersing roof fracture and energy release in time and space, transforming the originally concentrated periodic pressure events into multiple low-intensity, stepped pressure events. This embodiment significantly reduces the intensity of a single energy release and the probability of rockburst, reduces the amount of work and construction costs per operation, and the weakening operation is carried out simultaneously with coal mining without affecting production progress. It is applicable to the fields of rockburst prevention and safe coal mining.

[0043] Furthermore, the basic parameters of the coal mining face include: face length, periodic pressure step distance, coal mining machine cutting depth, basic roof thickness, and hydraulic support width.

[0044] Specifically, (1) Obtain the basic parameters of the coal mining face, including the length of the working face. Periodic pressure step size Coal mining machine cutting depth Basic top thickness and the width of the hydraulic support ;

[0045] (2) Calculate the number of coal cutting blades (number of independent weakening sections) during a single cycle of pressure application. The calculation formula is: ,in This represents the floor function;

[0046] (3) Calculate the weakening length of each segment. The calculation formula is: .

[0047] Furthermore, based on the basic parameters of the coal mining face, the roof of the face is divided along the strike into multiple independent weakened sections, including:

[0048] A coordinate system along the working face is established based on each weakening length, wherein each weakening length is calculated from the working face length in the basic parameters of the coal mining face and the number of coal cutting tools during a cycle of pressure.

[0049] The working face top plate is divided into multiple independent weakened segments according to the coordinate system.

[0050] Furthermore, the calculation steps for the weakening length of each segment include:

[0051] Based on the cycle pressing step distance and the coal mining machine cutting depth, calculate the number of cutting blades during one cycle pressing period;

[0052] The total number of independent weakened sections of the top plate is set to be numerically equal to the number of cutting blades during one cycle of pressing.

[0053] The length of each weakening segment is calculated based on the length of the working face and the total number of independent weakening segments of the top plate.

[0054] Specifically, (1) the roof is divided along the working face into The first independent weakening segment, the... The spatial extent of the segment is determined by the starting coordinates. and termination coordinates Confirmed, among which , , The segment numbering ranges from 1 to... ;

[0055] (2) Each weakened section corresponds to a hydraulic support group, which is responsible for supporting the corresponding top plate area.

[0056] Furthermore, establishing the correspondence between the independent weakened sections and the number of coal cutting tools includes:

[0057] The current cumulative number of coal cutters is determined based on the cumulative advance distance of the working face and the cutting depth of the coal mining machine.

[0058] Based on the current cumulative number of coal cutting blades and the total number of independent weakened sections of the roof, a model calculation is performed, and the weakened section number that should be weakened is determined according to the model calculation result.

[0059] Based on the weakened segment number, establish the correspondence between the independent weakened segment and the current cumulative number of coal cutting blades.

[0060] Specifically, (1) Establish weakened segment numbering Total number of coal cutting blades at the working face The corresponding relationship is as follows: when the cumulative number of coal cutting blades on the working face... satisfy At that time, for the first The segment is weakened, where mod represents the modulo operation;

[0061] (2) Cumulative number of coal cutters at the working face Based on the cumulative advance distance of the working face calculate, ,in This represents the floor function.

[0062] Furthermore, according to the aforementioned correspondence, the weakening treatment of each weakened section during the coal mining process includes:

[0063] Based on the determined weakening section number, weakening operation points are arranged at the joints of adjacent hydraulic supports within the corresponding weakening section range.

[0064] The roof at the work site is weakened by at least one of the following methods: blasting weakening, hydraulic fracturing, or rock breaking with an expansive agent. The weakening treatment extends through the basic roof thickness.

[0065] Specifically, (1) weaken the arrangement of work points at the joints of adjacent hydraulic supports, and the distance between work points is equal to the width of the hydraulic support. ;

[0066] (2) Weakening methods include at least one of explosive weakening, hydraulic fracturing, or rock breaking with expansive agents;

[0067] Taking hydraulic fracturing as an example, the specific steps include: at the weakening operation point, drilling a water injection borehole perpendicular to the top plate upwards, the depth of the water injection borehole being greater than the thickness of the basic top to penetrate the basic top; installing a sealing device in the water injection borehole to perform a sealing operation; injecting high-pressure water into the sealed water injection borehole using a high-pressure water pump to perform fracturing, and continuing to inject water until the top plate rock strata produce a fracture propagation signal, thus completing the weakening treatment of the operation point.

[0068] (3) Weakening the depth penetration of the basic top thickness .

[0069] More specifically, the weakening method is hydraulic fracturing, and the weakening parameters include a borehole depth greater than the basic top thickness. The drilling angle is perpendicular to the top plate and upwards, and a high-pressure water pump is used for fracturing.

[0070] Furthermore, by cyclically executing S3-S4, a stepped pressure-applying mode is formed that simultaneously mines coal and weakens the soil, including:

[0071] Repeatedly execute the process of determining the current number of coal cutting tools, determining the current weakening section number, and implementing roof weakening to disperse roof fracture and energy release in time and space, thereby achieving step-by-step pressure.

[0072] Specifically, by repeatedly executing steps S3 and S4, the roof fracture and energy release are dispersed in time and space, transforming concentrated periodic pressure events into multiple low-intensity stepped pressure events, thereby reducing the intensity of a single energy release and the probability of rockburst.

[0073] The following is a detailed description of this embodiment:

[0074] To solve the above-mentioned technical problems, the present invention provides a method for segmented weakening of the roof for preventing rockbursts, comprising the following steps:

[0075] Step S1: Determine the parameters for weakening the top plate segments:

[0076] (1) Obtain basic parameters of the coal mining face: working face length Periodic pressure step size Coal mining machine cutting depth Basic top thickness , width of hydraulic support .

[0077] (2) Calculate the number of coal cutting blades (number of independent weakening sections) during one cycle of pressure application:

[0078] ;

[0079] (3) Calculate the length of each independent weakened segment:

[0080] ;

[0081] In the formula: The number of coal cutting blades during a single cycle is also the number of independent weakening sections, expressed in units of individual pieces. The step distance is determined by the period, and the unit is meters. The cutting depth of the coal mining machine is expressed in meters. The length of each weakened segment is in meters; The length of the working surface is in meters; This is the floor function.

[0082] Step S2: Divide the weakened section of the top plate and associate it with the support group:

[0083] The roof is divided into sections along the working face. Each weakened segment is an independent weakened segment, and a coordinate system for each weakened segment is established. The spatial range of the segment is:

[0084] ;

[0085] ;

[0086] In the formula: For the first The starting coordinates of the segment, in meters; For the first The segment termination coordinates, in meters; The segment numbering ranges from 1 to... Each weakened section corresponds to a hydraulic support group, which is responsible for supporting its corresponding roof area.

[0087] Step S3, Determine the weakening sequence: (1) Establish the correspondence between the weakening segment number and the number of coal mining cutters. When the number of coal mining cutters... When the following conditions are met, for the first The segment is weakened:

[0088] ;

[0089] ;

[0090] In the formula: The cumulative number of coal cutting blades at the working face; The cumulative advance distance of the working face is expressed in meters; mod is the modulo operation. This is the floor function.

[0091] Step S4: Implement roof weakening:

[0092] (1) The top plate of the i-th segment is weakened. The weakening operation points are arranged at the joints of adjacent hydraulic supports, and the distance between the operation points is equal to the width of the support.

[0093] (2) Weakening methods may include, but are not limited to: blasting weakening, hydraulic fracturing, rock breaking with expansive agents, etc.

[0094] Taking hydraulic fracturing as an example, the specific steps include: at the weakening operation point, drilling a water injection borehole perpendicular to the top plate upwards, the depth of the water injection borehole being greater than the thickness of the basic top to penetrate the basic top; installing a sealing device in the water injection borehole to perform a sealing operation; injecting high-pressure water into the sealed water injection borehole using a high-pressure water pump to perform fracturing, and continuing to inject water until the top plate rock strata produce a fracture propagation signal, thus completing the weakening treatment of the operation point.

[0095] (3) The weakening depth should penetrate the basic top thickness. The specific weakening parameters are determined based on the selected weakening method and the on-site geological conditions.

[0096] Step S5, Cyclic Operation:

[0097] The steps S3-S4 are executed in a loop to form a continuous "one cut of coal mining, weakening a section" cycle operation process, which realizes the spatial and temporal dispersion of the roof of the working face and the step-like pressure.

[0098] This embodiment takes a typical coal mining face in a coal mine as an example, and specifically includes:

[0099] 1. Basic parameters of the working face:

[0100] The length of the coal mining face The cycle length is 300m, and the step distance is adjusted accordingly. The cutting depth of the coal mining machine is 30m. The basic top thickness is 0.8m. The hydraulic support is 15m wide. It is 1.5m.

[0101] 2. Determine the parameters for weakening the top plate segments:

[0102] Calculate the number of coal cutting blades during a single cycle of pressure application:

[0103] ;

[0104] Calculate the weakening length of each segment:

[0105] ;

[0106] Therefore, the top plate of the working face is divided into 38 independent weakened sections along the direction, each section being approximately 7.89 meters long.

[0107] 3. Divide the weakened sections of the roof slab and associate them with the support group:

[0108] Establish a coordinate system along the working face direction (X-axis direction), with the starting point (X=0) set on the side of the working face transport roadway. The spatial extent of the segment is determined by the starting coordinates. and termination coordinates Confirmed. For example:

[0109] Paragraph 1: m, m;

[0110] Paragraph 2: m, m;

[0111] …;

[0112] Paragraph 38: m, m;

[0113] Each weakened segment corresponds to one hydraulic support assembly. Due to the length of each segment... m, bracket width m, therefore each support group contains approximately That is, about 5 to 6 hydraulic supports, which are responsible for supporting their corresponding roof areas.

[0114] 4. Determine the weakening timing:

[0115] Establish weakened segment numbering With the number of coal cutting tools The corresponding relationship. When the cumulative number of coal cutting blades on the working face... satisfy At that time, for the first The segment is weakened. For example:

[0116] When making the first cut (k=1), Weaken the first paragraph.

[0117] When making the second cut (k=2), Weaken the second paragraph.

[0118] …;

[0119] When making the 39th cut (k=39), Then, weaken the first segment again (enter the next cycle to compress the loop).

[0120] 5. Implement roof weakening:

[0121] When the coal mining machine completes the first In the knife-cut coal mining operation, after the working face advanced 0.8m, the first... The top slab of the section was weakened.

[0122] Weaken the layout of work points: The work points are placed at the... At the joints of adjacent hydraulic supports within a section, the distance between work points is equal to 1.5m of the support width. For example, for a weakened section of approximately 7.89m in length, approximately 5 to 6 weakening work points are arranged.

[0123] Weakening method: Hydraulic fracturing is used as the weakening method in this embodiment.

[0124] Weakening parameters:

[0125] (1) Drilling depth: Penetrate the basic top, and the drilling depth is designed to be 18m (greater than the thickness of the basic top by 15m to ensure effective weakening).

[0126] (2) Drilling angle: Drill holes vertically upwards from the top plate.

[0127] (3) Fracturing parameters: Use a high-pressure water pump with a rated pressure of 50MPa. After sealing the hole with a sealing device, inject high-pressure water into the borehole. The fracturing time is about 10-15 minutes per hole until the crack propagation signal of the top rock layer is detected.

[0128] The weakening operation follows the coal mining process and is carried out under the support of hydraulic supports, without affecting the normal support of the working face.

[0129] 6. Cyclic operation:

[0130] Repeatedly performing coal cutting at the working face, determining the weakening sequence, and implementing roof weakening forms a cyclical operation flow of "one cut of coal mining, one section of weakening," which disperses the roof breaking and pressure process in time and space, ultimately achieving step-like pressure.

[0131] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for segmented weakening of the roof for preventing rockbursts, characterized in that, include: S1. Obtain basic parameters of the coal mining face; S2. Based on the basic parameters of the coal mining face, the roof of the working face is divided into multiple independent weakened sections along the strike. S3. Establish the correspondence between the independent weakened sections and the number of coal cutting tools; S4. According to the aforementioned correspondence, each weakened section is sequentially weakened during the coal mining process; S5. Repeat S3-S4 to form a stepped pressure mode in which coal mining and weakening are carried out simultaneously.

2. The method for segmented weakening of the roof for preventing rockbursts according to claim 1, characterized in that, The basic parameters of the coal mining face include: face length, periodic pressure step distance, coal mining machine cutting depth, basic roof thickness, and hydraulic support width.

3. The method for segmented weakening of the roof for preventing rockbursts according to claim 2, characterized in that, Based on the aforementioned basic parameters of the coal mining face, the roof of the face is divided along the strike into multiple independent weakened sections, including: A coordinate system along the working face is established based on each weakening length, wherein each weakening length is calculated from the working face length in the basic parameters of the coal mining face and the number of coal cutting tools during a cycle of pressure. The working face top plate is divided into multiple independent weakened segments according to the coordinate system.

4. A method for segmented weakening of the roof slab for preventing rockbursts according to claim 3, characterized in that, The calculation steps for each weakening length include: Based on the cycle pressing step distance and the coal mining machine cutting depth, calculate the number of cutting blades during one cycle pressing period; The total number of independent weakened sections of the top plate is set to be numerically equal to the number of cutting blades during one cycle of pressing. The length of each weakening segment is calculated based on the length of the working face and the total number of independent weakening segments of the top plate.

5. A method for segmented weakening of the roof slab for preventing rockbursts according to claim 4, characterized in that, Establishing the correspondence between the independent weakened sections and the number of coal cutting tools includes: The current cumulative number of coal cutters is determined based on the cumulative advance distance of the working face and the cutting depth of the coal mining machine. Based on the current cumulative number of coal cutting blades and the total number of independent weakened sections of the roof, a model calculation is performed, and the weakened section number that should be weakened is determined according to the model calculation result. Based on the weakened segment number, establish the correspondence between the independent weakened segment and the current cumulative number of coal cutting blades.

6. A method for segmented weakening of the roof slab for preventing rockbursts according to claim 1, characterized in that, Based on the aforementioned correspondence, the weakening treatment of each weakened section is carried out sequentially during the coal mining process, including: Based on the determined weakening section number, weakening operation points are arranged at the joints of adjacent hydraulic supports within the corresponding weakening section range. The roof at the work site is weakened by at least one of the following methods: blasting weakening, hydraulic fracturing, or rock breaking with an expansive agent. The weakening treatment extends through the basic roof thickness.

7. A method for segmented weakening of the roof for preventing rockbursts according to claim 1, characterized in that, The S3-S4 cycle is executed repeatedly to form a stepped pressure-applying mode that simultaneously mines coal and weakens the coal, including: Repeatedly execute the process of determining the current number of coal cutting tools, determining the current weakening section number, and implementing roof weakening to disperse roof fracture and energy release in time and space, thereby achieving step-by-step pressure.

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