An operation method for optimizing the coal pillar of the stop mining line by cutting the top to relieve pressure and protect the lane at the end of mining

Abstract

The present application provides an operation method for optimizing the stop-mining line coal pillar by cutting the top and relieving pressure to protect the tunnel at the end of mining, comprising: S10, collecting the engineering geological profile of the operation location, and determining the drilling site location, top cutting height, fan-shaped hole parameters and hydraulic fracturing parameters based on the engineering geological profile; S20, arranging the drilling site near the original stop-mining line according to the drilling site location; S30, setting fan-shaped holes in the drilling site according to the top cutting height and the fan-shaped hole parameters, and performing hydraulic fracturing in the fan-shaped holes according to the top cutting height and the hydraulic fracturing parameters; S40, continuing mining when the mining face advances to the original stop-mining line, anchoring the two sides of the tunnel, and monitoring the deformation and damage of the surrounding rock of the tunnel to be protected in real time; when the deformation rate of the surrounding rock of the tunnel exceeds the warning value, stopping mining immediately to form a new stop-mining line; the distance between the new stop-mining line and the original stop-mining line is the optimized stop-mining line coal pillar width; the method has the beneficial effects of improving the stability of the surrounding rock of the tunnel, optimizing the stop-mining line width, and having a good top cutting and pressure relief effect; and the method is applicable to the field of coal mining.

Description

Technical Field

[0001] The present application relates to the technical field of coal mining, and in particular to an operation method for cutting the top to relieve pressure, protecting the lane and optimizing the coal pillar of the stop mining line at the end of mining. Background Art

[0002] Roadways are various passages drilled between the surface and the ore body, used for transportation, mining, ventilation and drainage, pedestrian access, and various necessary preparatory works. They are generally divided into development roadways, preparation roadways, and mining roadways based on their purpose. Development roadways include transportation roadways, track roadways, and return air roadways, which are passages from the surface to the mining area. Mining roadways include cut holes, mining face transportation roadways, and return air roadways.

[0003] When underground mining in a coal mine enters the final mining stage, the mining face is mined to the vicinity of the original stop mining line. As the mining face advances forward during the mining process, the main tunnel is within the mining influence range, which directly affects the stability of the surrounding rock of the main tunnel. When the tunnel is severely deformed, it will affect normal operations such as underground transportation, ventilation, and pedestrians, which can easily cause danger.

[0004] In order to solve the above problems, a withdrawal channel is usually excavated, vertical holes are drilled in the withdrawal channel, and the final mining is carried out by blasting or hydraulic fracturing to cut the top and relieve pressure. However, this method has the problems of complex operation, high cost and low operating efficiency. Summary of the Invention

[0005] In order to solve one of the above technical defects, the present application provides an operation method for cutting the top to relieve pressure and protect the lane at the end of mining to optimize the coal pillar of the stop mining line.

[0006] The present application provides an operation method for optimizing the coal pillar of the stop mining line by cutting the top to relieve pressure and protect the lane at the end of mining, comprising the following steps:

[0007] S10, collecting an engineering geological profile of the operation location, and determining a drilling site location, a top cutting height, fan-shaped hole parameters, and hydraulic fracturing parameters based on the collected engineering geological profile;

[0008] S20, arranging drilling sites near the original stop-mining line according to the determined drilling site locations, with the drilling sites being arranged on both sides of the mining face;

[0009] S30, setting fan-shaped holes in the drilling site according to the determined top cutting height and fan-shaped hole parameters, and then performing hydraulic fracturing in the fan-shaped holes according to the determined top cutting height and hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main roadway; the fan-shaped holes may include a plurality of drill holes, and the plurality of drill holes are arranged obliquely toward the middle of the mining working face;

[0010] S40: When the mining face advances to the original stop-mining line, continue mining, and at the same time, reinforce the two sides of the main tunnel to be protected with anchor cables, and monitor the deformation and damage of the surrounding rock of the main tunnel to be protected in real time; when the deformation rate of the surrounding rock of the main tunnel to be protected exceeds the warning value, stop mining immediately and form a new stop-mining line;

[0011] The distance between the new stop mining line and the original stop mining line is the optimized stop mining line coal pillar width.

[0012] Preferably, the step S10 of collecting the engineering geological profile of the operation location specifically includes:

[0013] S101, collect engineering geological profiles of the mining face and the main tunnel to be protected, including coal seam inclination, main tunnel excavation operation procedures, mining operation procedures of the mining face, drilling histograms, mining engineering plan drawings, hydrogeological conditions, structural conditions and mining impacts;

[0014] S102, collecting the geomechanical characteristics of the surrounding rock of the main tunnel to be protected to determine the position and thickness of the roof rock layer that plays a key role in the pressure on the mining face; the geomechanical characteristics of the surrounding rock include the lithology and thickness of the roof rock layer of the main tunnel, the physical and mechanical properties of the surrounding rock, the ground stress state, the pressure step distance of the mining face, and the expansion coefficient of the goaf.

[0015] More preferably, the step S10 of determining the drilling site location, top cutting height, fan-shaped hole parameters and hydraulic fracturing parameters according to the collected engineering geological profile specifically includes:

[0016] S103, determining the drilling site location;

[0017] S104, determining fan-shaped hole parameters based on the position and thickness of the roof rock layer that plays a key role in the pressure of the mining face and the coal seam inclination, wherein the fan-shaped hole parameters include: the relative position of the fan-shaped hole and the stop-mining line, the hole spacing, the number of drill holes, the drill hole length, and the drill hole angle;

[0018] S105, determining hydraulic fracturing parameters according to the uniaxial tensile strength and ground stress state of the rock in the fractured rock formation, wherein the hydraulic fracturing parameters include: hydraulic pressure, fracturing direction, and fracturing section;

[0019] S106, calculate the top cutting height H:

[0020]

[0021] Where: is the sum of the heights of different rock layers, in meters; M is the thickness of the mined coal seam, in meters; K p is the average expansion coefficient of the goaf.

[0022] More preferably, the step S104, determining the fan-shaped hole parameters according to the position and thickness of the roof rock layer that plays a key role in the pressure of the mining face and the coal seam inclination, specifically includes:

[0023] (1) The dip angle of the nearly horizontal coal seam is less than 8°, and two groups of drill holes are arranged symmetrically, with each group containing 6 to 12 drill holes;

[0024] (2) The dip angle of the gently inclined coal seam is 8-25°, 5-11 holes are drilled in the upper part of the stope, and the number of holes drilled in the lower part of the stope is increased by 1-2 compared with the holes drilled in the upper part of the stope;

[0025] (3) The dip angle of the medium-sloping coal seam is 25-45°, the upper part of the stope is 4-10 boreholes, and the number of boreholes in the lower part of the stope is arranged to increase by 3-4 compared with the upper part of the stope;

[0026] (4) The inclination angle of the steeply inclined coal seam is greater than 45°. There are 3 to 9 drill holes in the upper part of the stope, and the number of drill holes in the lower part of the stope is increased by 5 to 6 compared with the drill holes in the upper part of the stope.

[0027] More preferably, the step S30 of performing hydraulic fracturing in the fan-shaped hole according to hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main tunnel specifically includes:

[0028] Arrange high-pressure water injection pumps in the drilling site;

[0029] Use a high-pressure water injection pump to perform multiple hydraulic fracturing in each borehole in a backward manner, with a frequency of one fracturing every 2m and each fracturing lasting ≥30min. Stop the hydraulic fracturing when the water pressure drops sharply; repeat the above steps until the roof rock formation is completely fractured.

[0030] Preferably, in step S40, the deformation and damage conditions of the surrounding rock of the tunnel include: roof subsidence, floor heave, two-wall displacement and roof delamination conditions.

[0031] The method for cutting the top and relieving pressure to protect the lane at the end of mining provided in this application is adopted. The top is cut by hydraulic fracturing, which improves the stability of the surrounding rock of the large lane, optimizes the width of the coal pillar at the end of mining, further improves the recovery rate of coal resources, and increases economic benefits. The working cycle is short, the cost is reduced, and the efficiency of the end of mining is improved. It solves the problems in the prior art of needing to excavate a retreat channel, vertically drill holes in the retreat channel, and cut the top and relieve pressure by blasting or hydraulic fracturing, which are complicated, costly, and inefficient. Since the middle part of the roof rock layer is easier to break than the two sides, the fan-shaped distribution of multiple boreholes makes the boreholes on both sides of the roof rock layer more dense, and the boreholes in the middle of the roof rock layer more sparse. When the lithology and thickness of the roof rock layer are basically the same, the top cutting and pressure relief effect on the roof rock layer is better.

[0032] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the contents indicated in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 A schematic diagram of the inclined profile design of the mining working face provided in Example 1 of the present application;

[0035] Figure 2 This is a schematic diagram of the cross-sectional design of the mining working face provided in Example 1 of the present application;

[0036] Figure 3 This is a schematic diagram of the inclined profile design of the mining working face provided in Example 2 of this application;

[0037] Figure 4 This is a schematic diagram of the cross-sectional design of the mining face provided in Example 2 of this application. DETAILED DESCRIPTION

[0038] In order to make the technical solutions and advantages of the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, and are not an exhaustive list of all the embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other unless they conflict.

[0039] The main tunnel to be protected in this application is the one closest to the mining working face.

[0040] Example 1

[0041] Figure 1 This is a schematic diagram of the inclined profile design of the mining working face provided in Example 1 of this application. Figure 2 This is a schematic diagram of the cross-sectional design of the mining working face provided in Example 1 of this application. Figure 2 The direction indicated by the arrow in the middle is the direction of the mining operation face. Figure 1 and Figure 2 As shown, the present application provides an operation method for cutting the top to relieve pressure and protect the lane at the end of mining to optimize the coal pillar of the stop mining line, including the following steps:

[0042] S10, collecting the engineering geological profile of the operation location of the mining area A, and determining the drilling site location, top cutting height, fan-shaped hole parameters and hydraulic fracturing parameters based on the collected engineering geological profile;

[0043] S101, collect engineering geological information of the mining face and the main tunnel to be protected, including coal seam inclination, main tunnel excavation operation procedures, mining face mining operation procedures, drilling histogram, mining engineering plan, hydrogeological conditions, structural conditions and mining impacts; specifically, the coal seam inclination is 15°;

[0044] S102, collecting geomechanical characteristics of the surrounding rock of the proposed protected tunnel to determine the position and thickness of the roof rock layer that plays a key role in the pressure on the mining face; the geomechanical characteristics of the surrounding rock include the lithology and thickness of the tunnel roof rock layer, the physical and mechanical properties of the surrounding rock, the ground stress state, the pressure step distance of the mining face, and the expansion coefficient of the goaf;

[0045] The rock layers of the main tunnel roof are as follows from top to bottom: mudstone 2.1m, limestone 9.95m, fine-grained sandstone 2.0m, siltstone 1.85m, sandy mudstone 3.5m, and No. 8 coal 2.65m;

[0046] The hydraulic fracturing method was used to measure the ground stress in the tunnel, and the maximum principal stress was 11.5 MPa, which was perpendicular to the tunnel axis. The minimum principal stress was 7.8 MPa, which was parallel to the tunnel axis. The expansion coefficient of the goaf was 1.36, and the height between the mining face and the coal seam was 2.65 m.

[0047] The roof rock layer that plays a key role in the pressure of the mining face is the limestone 7.35m away from the roadway roof, and its rock layer thickness is 9.95m;

[0048] S103, determining the drilling site location;

[0049] S104, determining fan-shaped hole parameters based on the position and thickness of the roof rock layer that plays a key role in the pressure of the mining face and the coal seam inclination, wherein the fan-shaped hole parameters include: the relative position of the fan-shaped hole and the stop-mining line, the hole spacing, the number of drill holes, the drill hole length, and the drill hole angle;

[0050] Specifically, the thicker the roof rock layer, the smaller the fan-shaped hole spacing; the thinner the roof rock layer, the larger the fan-shaped hole spacing; the greater the coal seam inclination, the greater the difference in the number of fan-shaped holes drilled on both sides of the mining face;

[0051] Specifically, there are 18 drill holes in total in the two drill sites, of which 8 drill holes H1-H8 are set in the drill site in the upper part of the stope, and 10 drill holes Y1-Y10 are set in the lower part of the stope;

[0052] The drilling angles of H1-H8 are: 0°, 5°, 10°, 16°, 24°, 35°, 51°, 70°, and the drilling lengths are: 17.4m, 19.0m, 22.6m, 27.8m, 34.2m, 41.48m, 49.3m, 48.1m respectively;

[0053] The drilling angles of Y1-Y10 are: 84°, 76°, 67°, 59°, 53°, 47°, 42°, 39°, 34°, 30°, and the drilling lengths are: 18.5m, 20.0m, 22.0m, 24.8m, 28.4m, 32.7m, 37.7m, 43.3m, 49.3m, 48.1m;

[0054] Since the middle of the roof rock layer is easier to break than the two sides, the fan-shaped distribution of multiple drill holes makes the drill holes on both sides of the roof rock layer more dense and the drill holes in the middle of the roof rock layer more sparse. Under the condition that the lithology and thickness of the roof rock layer are basically the same, the roof rock layer cutting and pressure relief effect is better;

[0055] S105, determining hydraulic fracturing parameters according to the uniaxial tensile strength and ground stress state of the rock in the fractured rock formation, wherein the hydraulic fracturing parameters include: hydraulic pressure, fracturing direction, and fracturing section;

[0056] Specifically, the hydraulic pressure is 20 MPa;

[0057] S106, calculate the top cutting height H:

[0058]

[0059] Where: is the sum of the heights of different rock layers, in meters; M is the thickness of the mined coal seam, in meters; K p is the average expansion coefficient of the goaf.

[0060] S20, arranging drilling sites near the original stop-mining line according to the determined drilling site positions, with the drilling sites being arranged on both sides of the mining working face.

[0061] S30, setting fan-shaped holes in the drilling site according to the determined top cutting height and fan-shaped hole parameters, and then performing hydraulic fracturing in the fan-shaped holes according to the determined top cutting height and hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main roadway; the fan-shaped holes may include a plurality of drill holes, and the plurality of drill holes are arranged obliquely toward the middle of the mining working face;

[0062] Furthermore, a high-pressure water injection pump is arranged in the drilling site;

[0063] Use a high-pressure water injection pump to perform multiple hydraulic fracturing in each borehole in a backward manner, with a frequency of one fracturing every 2m and each fracturing lasting ≥30min. Stop the hydraulic fracturing when the water pressure drops sharply; repeat the above steps until the roof rock formation is completely fractured.

[0064] S40: When the mining face advances to the original stop-mining line, continue mining, and at the same time, reinforce the two sides of the main tunnel to be protected with anchor cables, and monitor the deformation and damage of the surrounding rock of the main tunnel to be protected in real time; when the deformation rate of the surrounding rock of the main tunnel to be protected exceeds the warning value, stop mining immediately and form a new stop-mining line;

[0065] Furthermore, the deformation and damage of the surrounding rock of the tunnel include: roof subsidence, floor heave, two-wall displacement and roof separation;

[0066] The distance between the new stop mining line and the original stop mining line is the optimized stop mining line coal pillar width.

[0067] In the example provided in Example 1 of the present application, the width of the coal pillar at the stop mining line is optimized from the previous 76m to 50m, which is shortened by 26m.

[0068] Example 2

[0069] Figure 3 This is a schematic diagram of the inclined profile design of the mining working face provided in Example 2 of this application. Figure 4 This is a schematic diagram of the cross-sectional design of the mining face provided in Example 2 of this application. Figure 4 The direction indicated by the arrow in the middle is the direction of the mining operation face. Figure 3 and Figure 4 As shown, the present application provides an operation method for cutting the top to relieve pressure and protect the lane at the end of mining to optimize the coal pillar of the stop mining line, including the following steps:

[0070] S10, collecting the engineering geological profile of the operation location of the B mining area, and determining the drilling site location, top cutting height, fan-shaped hole parameters and hydraulic fracturing parameters based on the collected engineering geological profile;

[0071] S101, collect engineering geological information of the mining face and the main tunnel to be protected, including coal seam inclination, main tunnel excavation operation procedures, mining operation procedures of the mining face, drilling histogram, mining engineering plan, hydrogeological conditions, structural conditions and mining impacts; specifically, the coal seam inclination is 26°;

[0072] S102, collecting geomechanical characteristics of the surrounding rock of the proposed protected tunnel to determine the position and thickness of the roof rock layer that plays a key role in the pressure on the mining face; the geomechanical characteristics of the surrounding rock include the lithology and thickness of the tunnel roof rock layer, the physical and mechanical properties of the surrounding rock, the ground stress state, the pressure step distance of the mining face, and the expansion coefficient of the goaf;

[0073] The rock layers of the main tunnel roof are as follows from top to bottom: fine-grained sandstone 5.8m, limestone 5.5m, mudstone 1.4m, No. 14 coal 0.6m, sandy mudstone 0.8m, mudstone 7.0m, No. 15 coal 6.0m (of which the top coal is 3m thick);

[0074] The hydraulic fracturing method was used to measure the ground stress in the roadway. The maximum principal stress was 8 MPa vertical stress, perpendicular to the roadway axis; the minimum principal stress was 5 MPa horizontal stress, parallel to the roadway axis; the goaf expansion coefficient was 1.21, and the height between the mining face and the coal seam was 3.0 m.

[0075] The roof rock strata that play a key role in the pressure of the mining face are limestone and fine-grained sandstone 14.0m away from the roadway roof, with rock layer thicknesses of 5.5m and 5.8m respectively;

[0076] S103, determining the drilling site location;

[0077] S104, determining fan-shaped hole parameters based on the position and thickness of the roof rock layer that plays a key role in the pressure of the mining face and the coal seam inclination, wherein the fan-shaped hole parameters include: the relative position of the fan-shaped hole and the stop-mining line, the hole spacing, the number of drill holes, the drill hole length, and the drill hole angle;

[0078] Specifically, there are 17 drill holes in total in the two drill sites, of which 7 drill holes E1-E7 are set in the drill site in the upper part of the stope, and 10 drill sites F1-F10 are set in the lower part of the stope;

[0079] The drilling angles of E1-E7 are: 77°, 57°, 36°, 20°, 8°, -3°, -9°, and the drilling lengths are: 25.5m, 25.0m, 28.1m, 34.0m, 43.8m, 55.1m, 55.7m respectively;

[0080] The drilling angles of F1-F10 are: 39°, 43°, 47°, 50°, 54°, 59°, 64°, 71°, 79°, 88°, and the drilling lengths are: 28.1m, 31.0m, 34.9m, 39.9m, 45.7m, 52.5m, 60.0m, 68.3m, 75.2m, 71.1m respectively;

[0081] S105, determining hydraulic fracturing parameters according to the uniaxial tensile strength and ground stress state of the rock in the fractured rock formation, wherein the hydraulic fracturing parameters include: hydraulic pressure, fracturing direction, and fracturing section;

[0082] Specifically, the hydraulic pressure is 20 MPa;

[0083] S106, calculate the top cutting height H:

[0084]

[0085] Where: is the sum of the heights of different rock layers, in meters; M is the thickness of the mined coal seam, in meters; K p is the average expansion coefficient of the goaf.

[0086] S20, arranging drilling sites near the original stop-mining line according to the determined drilling site positions, with the drilling sites being arranged on both sides of the mining face.

[0087] S30, setting fan-shaped holes in the drilling site according to the determined top cutting height and fan-shaped hole parameters, and then performing hydraulic fracturing in the fan-shaped holes according to the determined top cutting height and hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main roadway; the fan-shaped holes may include a plurality of drill holes, and the plurality of drill holes are arranged obliquely toward the middle of the mining working face;

[0088] Furthermore, a high-pressure water injection pump is arranged in the drilling site;

[0089] Use a high-pressure water injection pump to perform multiple hydraulic fracturing in each borehole in a backward manner, with a frequency of one fracturing every 2m and each fracturing lasting ≥30min. Stop the hydraulic fracturing when the water pressure drops sharply; repeat the above steps until the roof rock formation is completely fractured.

[0090] S40: When the mining face advances to the original stop-mining line, continue mining, and at the same time, reinforce the two sides of the main tunnel to be protected with anchor cables, and monitor the deformation and damage of the surrounding rock of the main tunnel to be protected in real time; when the deformation rate of the surrounding rock of the main tunnel to be protected exceeds the warning value, stop mining immediately and form a new stop-mining line;

[0091] Furthermore, the deformation and damage of the surrounding rock of the tunnel include: roof subsidence, floor heave, two-wall displacement and roof separation;

[0092] The distance between the new stop mining line and the original stop mining line is the optimized stop mining line coal pillar width.

[0093] In the example provided in Example 2 of the present application, the width of the coal pillar at the stop mining line is optimized from the previous 88m to 65m, which is shortened by 23m.

[0094] The method for cutting the top and relieving pressure to protect the tunnel and optimize the coal pillar of the stop mining line provided in this application is adopted. The top is cut by hydraulic fracturing, which improves the stability of the surrounding rock of the large tunnel, optimizes the width of the coal pillar of the stop mining line, further improves the recovery rate of coal resources, and increases economic benefits; the working cycle is short, the cost is reduced, and the efficiency of the end mining operation is improved, which solves the problems in the existing technology of needing to excavate a withdrawal channel, vertically drill holes in the withdrawal channel, and cut the top and relieve pressure by blasting or hydraulic fracturing, which are complicated, costly, and have low operating efficiency.

[0095] In the description of this application, it should be understood that the terms "middle", "both sides", "axial", "length", "width", "thickness", "horizontal", "vertical", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0097] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0098] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for optimizing the coal pillar at the stop mining line by cutting the top to relieve pressure and protect the lane at the end of mining, characterized in that: The following steps are involved: S10, collecting the engineering geological profile of the operation location, and determining the drilling site location, top cutting height, fan-shaped hole parameters and hydraulic fracturing parameters based on the collected engineering geological profile, including: S103, determining the drilling site location; S104, determining fan-shaped hole parameters based on the position and thickness of the roof rock layer that plays a key role in the pressure of the mining face and the coal seam inclination. The fan-shaped hole parameters include: the relative position of the fan-shaped hole and the stop-production line, the hole spacing, the number of drill holes, the drill hole length, and the drill hole angle; specifically, including: (1) When the dip angle of the near-horizontal coal seam is less than 8°, two groups of drill holes are arranged symmetrically, with each group containing 6 to 12 drill holes; (2) The dip angle of the gently inclined coal seam is 8-25°, 5-11 holes are drilled in the upper part of the stope, and the number of holes drilled in the lower part of the stope is 1-2 more than that in the upper part of the stope; (3) The dip angle of the medium-sloping coal seam is 25-45°, the upper part of the stope is 4-10 boreholes, and the lower part of the stope is arranged with 3-4 more boreholes than the upper part of the stope; (4) For steeply inclined coal seams with an inclination angle of >45°, there are 3 to 9 drill holes in the upper part of the stope, and the number of drill holes in the lower part of the stope is 5 to 6 more than that in the upper part of the stope; S105, determining hydraulic fracturing parameters according to the uniaxial tensile strength and ground stress state of the rock in the fractured rock formation, wherein the hydraulic fracturing parameters include: hydraulic pressure, fracturing direction, and fracturing section; The drill holes on both sides of the roof rock layer are dense, while the drill holes in the middle of the roof rock layer are sparse; S106, calculate the top cutting height H: ； Where: is the sum of the heights of different rock layers, in meters; M is the thickness of the mined coal seam, in meters; K p is the average expansion coefficient of the goaf; S20, arranging drilling sites near the original stop-mining line according to the determined drilling site locations, with the drilling sites being arranged on both sides of the mining face; S30, setting fan-shaped holes in the drilling site according to the determined top cutting height and fan-shaped hole parameters, and then performing hydraulic fracturing in the fan-shaped holes according to the determined top cutting height and hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main roadway; the fan-shaped holes may include a plurality of drill holes, and the plurality of drill holes are arranged obliquely toward the middle of the mining working face; S40: When the mining face advances to the original stop-mining line, continue mining, and at the same time, reinforce the two sides of the main tunnel to be protected with anchor cables, and monitor the deformation and damage of the surrounding rock of the main tunnel to be protected in real time; when the deformation rate of the surrounding rock of the main tunnel to be protected exceeds the warning value, stop mining immediately and form a new stop-mining line; The distance between the new stop mining line and the original stop mining line is the optimized stop mining line coal pillar width.

2. The method for optimizing the coal pillar at the stop mining line by cutting the top and releasing the pressure to protect the lane at the end of mining according to claim 1 is characterized in that: The step S10, collecting the engineering geological profile of the operation location, specifically includes: S101, collect engineering geological profiles of the mining face and the main tunnel to be protected, including coal seam inclination, main tunnel excavation operation procedures, mining operation procedures of the mining face, drilling histograms, mining engineering plan, hydrogeological conditions, structural conditions and mining impacts; S102, collecting the geomechanical characteristics of the surrounding rock of the main tunnel to be protected to determine the position and thickness of the roof rock layer that plays a key role in the pressure on the mining face; the geomechanical characteristics of the surrounding rock include the lithology and thickness of the roof rock layer of the main tunnel, the physical and mechanical properties of the surrounding rock, the ground stress state, the pressure step distance of the mining face, and the expansion coefficient of the goaf.

3. The method for optimizing the coal pillar at the stop mining line by cutting the top and releasing the pressure to protect the lane at the end of mining according to claim 1 is characterized in that: The step S30 is to perform hydraulic fracturing in the fan-shaped hole according to the hydraulic fracturing parameters to cut off the roof rock layer and reduce the pressure of the surrounding rock of the main tunnel, which specifically includes: Arrange high-pressure water injection pumps in the drilling site; Use a high-pressure water injection pump to perform multiple hydraulic fracturing in each borehole in a backward manner, with a frequency of one fracturing every 2m and each fracturing lasting ≥30min. Stop the hydraulic fracturing when the water pressure drops sharply; repeat the above steps until the roof rock formation is completely fractured.

4. The method for optimizing the coal pillar at the stop mining line by cutting the top to relieve pressure and protect the lane at the end of mining according to claim 1 is characterized in that: In step S40, the deformation and damage conditions of the surrounding rock of the tunnel include: roof subsidence, floor heave, two-wall displacement and roof separation.

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