Working face roof cutting-resistance weakening mechanism and system roadway surrounding rock control method

Abstract

The invention belongs to the technical field of coal mining, and particularly relates to a working face roof cutting-resistance weakening mechanism and a system roadway surrounding rock control method. Comprising the following steps that S1, based on an overlying strata pressure-bearing arch mechanical model, the span and height of a pressure-bearing arch formed after mining of a working face are calculated, and the top cutting height of a target rock stratum is determined; s2, arranging a first blasting top cutting hole near a mining stopping line of the working face to prevent a top plate from forming a cantilever structure when the working face is mined at the end; s3, a second blasting blocking pressure relief hole is formed in front of the protected system roadway, and high stress in the high-position bearing structure is blocked from being continuously transmitted to the protected system roadway; and S4, high stress of the working face is concentrated between the working face and the protected system roadway through the synergistic effect of the multiple drilled holes. Formation of a large-span cantilever structure is effectively avoided, the peak value size and range of an additional stress field are reduced, a downward transmission path of high stress in a high-position bearing structure is blocked, and therefore the stability of roadway surrounding rock of a protected system is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mining, and particularly relates to a method for controlling the surrounding rock of a working face roof cutting-resistance weakening mechanism and a system roadway. Background Technique

[0002] When the working face is mined, the original stress state around the stope is broken, resulting in the redistribution of stress in front of the coal wall, that is, the appearance of advanced abutment pressure. During the mining period, the advanced pressure also moves forward continuously. Due to the existence of a certain thickness and hard rock formation above the working face, its strength is relatively high and its bending resistance is relatively strong, and it is not easy to break quickly under the action of mining stress, and it is extremely easy to form a large-span cantilever structure. The formation of this structure will impose additional loads and bending moments on the cantilever structure of the target rock formation. And as the working face continues to advance, when the high-position bearing large structure reaches the breaking span, the elastic energy accumulated on the structure appears to be damaged when it is the largest, and its internal high stress and the load of the loose overlying rock in the goaf also transfer downward. Under the combined action of the two, strong mine pressure manifestations occur in a large area in front of and behind the working face.

[0003] Chinese Patent with Patent Publication No. CN117307169A discloses a method for enhancing blasting and roof cutting and pressure relief in a high-level roadway hard roof. A high-level roadway is constructed in the hard roof, and a shaped charge is used for blasting to generate a directional crack surface, and a slip zone is generated in the hard roof, and a new free surface is provided for the blasting of adjacent blast holes; an enhanced blasting hole is constructed between two shaped charges, and the millisecond time is reasonably controlled so that the shaped charge detonates first and the enhanced blasting hole detonates later, so that the slip friction between the blocks is reduced, and the blocks cut by the shaped charge can collapse more easily. The roof cutting and pressure relief enhanced blasting method proposed by the present invention can not only achieve the effect of blasting and breaking the roof, but also make the hard roof in blocks collapse smoothly, release the pressure of the overlying rock formation in time, weaken the pressure in front of the mining face, and reduce the risk of rock burst in deep coal mines. The above-mentioned invention cannot weaken the magnitude of the additional load and bending moment of the high-level rock formation on the cantilever structure of the target rock formation from the root cause, and does not consider the continuous influence of the high stress inside the high-level bearing layer on the protected system roadway. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that in the above-mentioned prior art, it is impossible to weaken the magnitude of the additional load and bending moment of the high-level rock formation on the cantilever structure of the target rock formation from the root cause, and the continuous influence of the high stress inside the high-level bearing layer on the protected system roadway is not considered.

[0005] The present invention proposes a double - layer control system for protecting the surrounding rock of the system roadway in front of the working face by means of "one - time blasting to cut the top + secondary blocking and pressure relief". The present invention proposes a method for determining the target horizon affecting the dynamic load intensity during the end - mining period and the quantitative design method for the blocking and pressure - relief position; through the active construction of the stress buffer and release area, the energy dissipation of the high stress inside the high - level bearing structure is realized, the stress transfer effect of the high - level rock strata is reduced, so as to weaken the disturbance to the protected roadway.

[0006] The technical solution adopted by the present invention includes the following steps:

[0007] S1: Based on the mechanical model of the overlying rock bearing arch, calculate the span and height of the bearing arch formed after the working face is mined, and determine the cutting - top height of the target rock stratum;

[0008] S2: Arrange the first blasting cutting - top line holes in front of the working - face stop - line to prevent the formation of a cantilever structure at the end - mining of the working face;

[0009] S3: Arrange the second blasting blocking and pressure - relief holes in front of the protected system roadway to block the continuous transmission of the high - stress system inside the high - level bearing structure to the protected system roadway;

[0010] S4: Through the cooperative action of multiple drill holes, concentrate the high stress of the working face between the working face and the protected system roadway.

[0011] By adopting the above - mentioned technical solution, arranging the first blasting cutting - top holes near the working - face stop - line can effectively prevent the formation of a cantilever structure, and significantly reduce the peak value and range of the additional stress field. While arranging the second blasting blocking and pressure - relief holes behind the stop - line and in front of the protected system roadway can effectively block the transmission of the high stress generated by the working face to the system roadway. Using the method of the cooperative action of multiple drill holes to concentrate the high stress of the working face in a specific area can avoid the direct damage to the system roadway caused by stress concentration, help to maintain the stability of the surrounding rock, and reduce the cost and frequency of roadway maintenance. By scientifically calculating the span and height of the bearing arch of the target rock stratum and accurately arranging the cutting - top position and blocking position, it can not only effectively control the weakening process of the roof, but also shorten the periodic weighting interval, reduce the dynamic load intensity, thus improving the overall mining efficiency.

[0012] Further, in step 1, from the force system balance, we can get:

[0013]

[0014] P = T;

[0015]

[0016] Where:

[0017] P = Nf

[0018] In the formula, f is the solidity coefficient of the overburden, the arch height is h, the span is b, the length of the working face is l, q is the load, T is the horizontal tangential support force of the arch top, and P and N are the reaction forces at the arch foot;

[0019] Let the safety factor be 2, and combine the above formulas to get:

[0020] T=2Nf

[0021] From any point (x, y) on the pressure arch, the axis equation can be obtained as:

[0022]

[0023] The angle between the crack sliding surface of the coal wall in the working face and the side of the coal wall at the bottom of the goaf is θ, which is obtained from the active rock mass pressure theory:

[0024]

[0025] In the formula, —Internal friction angle of overlying rock;

[0026] Combining the above formulas, the span b and height h of the pressure arch can be expressed as:

[0027]

[0028] By adopting the above technical solution, the span and height of the pressure arch can be accurately calculated through the analysis of force balance. This method combines the stress state of the pressure arch and the actual situation of the rock formation, thus providing a scientific basis for mining operations. This not only improves the ability to predict the behavior of the rock formation, but also helps to reduce the risk of rock formation instability caused by uneven loads. By setting the safety factor, it can effectively control the possible risks in the mining process, ensure the stability of the pressure arch during mining, and avoid potential dangers caused by rock formation instability or collapse. Through the accurate calculation of the span, arch height and other parameters of the pressure arch, the arrangement of blasting holes in the mining process and the implementation of the top cutting pressure relief strategy can be optimized. In this way, the stress concentration area can be reduced during the mining process, and excessive rock damage can be avoided. By considering the angle between the crack sliding surface of the coal wall of the working face and the side of the coal wall at the bottom of the goaf, and combining the active rock pressure theory, the stress state of the rock mass can be further accurately determined, which helps to optimize the pressure relief scheme in the actual mining process. This can effectively reduce the possibility of rock deformation and improve the stability of coal mining. By clarifying the specific span and height parameters of the pressure arch and combining factors such as the friction angle, the rock behavior of the working face can be effectively controlled and sudden problems caused by uneven distribution of rock stress can be prevented. This combination of theory and practical operation can provide more accurate support and guidance for each link in the coal mining process.

[0029] Further, in step S2, a first blasting roof cutting line hole is arranged near the mining stop line of the working face to prevent the formation of a cantilever structure on the roof during the final mining of the working face. The roof cutting blasting hole is arranged above the mining protection coal pillar area 8 - 10 m behind the stop line.

[0030] By adopting the above technical solutions, scientifically calculating and determining the arrangement position of the roof cutting blasting hole, selecting appropriate hole diameters and hole spacings, and precisely controlling the release direction and intensity of blasting energy, the precise cutting of the target rock stratum can be achieved. It can effectively release the stress of the target rock stratum in advance, thereby reducing the pressure accumulation in the rock mass, preventing the overlying rock stratum from applying additional loads and bending moments to the cantilever structure of the target rock stratum, and causing high stress concentration inside the rock mass. This method of pre-pressure relief helps to reduce potential hazards in subsequent mining. By reducing the rock stratum pressure, the stability of the mine can be ensured during the mining process, the safety of the working face can be enhanced, and the probability of emergencies during operation can be reduced. Using the directional cumulative blasting technology can more accurately achieve the predetermined cutting effect, reduce unnecessary material waste and energy consumption, improve resource utilization rate. The reasonable arrangement of the blasting roof cutting holes can help better manage the roof movement, making the subsequent mining operations smoother, improving the overall work efficiency. The directional cumulative blasting technology allows adjusting the blasting parameters according to different geological conditions and engineering requirements, providing greater flexibility and adaptability. Using this technology, the caving time and spatial range of the roof can be controlled in a planned manner, which is beneficial to realizing continuous and mechanized mining operations, and further enhancing the operability and controllability of the project.

[0031] Further, a second blasting barrier pressure relief hole is arranged in front of the roadway of the protected system to block the continuous transmission of high stress inside the high - level bearing structure to the roadway of the protected system. The barrier pressure relief holes are arranged obliquely upward in the two crossheadings of the working face, showing a fan - shaped overall, and the position is in the stop coal pillar area 20 - 30 m in front of the roadway of the protected system.

[0032] By adopting the above technical solutions, the barrier pressure relief holes are reasonably arranged, which can effectively reduce the continuous influence of the stress of the high-position bearing structure on the roadway of the protected system. At the same time, it can also weaken the continuity of the bearing arch of the high-position rock stratum, cause the bearing arch to gradually collapse, further reduce the stress transfer effect of the high-position rock stratum, and thus weaken the disturbance to the protected roadway. This design helps to weaken potential risk areas in advance and improve the safety of the working environment. The fan-shaped arrangement can make the pressure relief effect cover a wider area and ensure the effective control and treatment of the target rock stratum. Compared with the linear arrangement, the fan-shaped arrangement can better adapt to the changes in geological structures, optimize the pressure relief path, and thus improve work efficiency. Setting a 6-meter spacing between the bottoms of the barrier pressure relief holes can form a cavity area and a broken zone structure in front of the roadway of the protected system, forming a continuous pressure relief surface. This structure can effectively absorb the dynamic and static stress energy transmitted downward by the high-position bearing structure through its own plastic deformation and compaction effect, thereby reducing the stress magnitude.

[0033] Furthermore, through the collaborative action of multiple boreholes, the high stress on the working face is concentrated between the working face and the roadway of the protected system.

[0034] By adopting the above technical solutions, the roof cutting and blocking weakening mechanism realizes the active optimization of the surrounding rock stress field and the reconstruction of the energy transfer path through the collaborative control strategy of "cutting the roof first and blocking later". The first cut-top blasting accurately cuts the target rock stratum, eliminates the formation conditions of the large-span cantilever structure, reduces the additional load and bending moment generated by the roof breakage from the source, and avoids the stress concentration superposition effect; the second barrier pressure relief blasting forms a composite structure of a cavity and a broken zone in the coal pillar area. Through the rock mass swelling deformation and crack friction effect, it effectively attenuates the dynamic and static stress energy transmitted by the high-position rock stratum and constructs a mechanical isolation barrier. The spatio-temporal collaborative effect of the two-stage blasting confines the advanced abutment stress on the working face and the high-position breakage energy between the two control areas, promotes the migration and dissipation of the high stress to the goaf side, blocks the stress transfer path, and significantly reduces the disturbance intensity of the roadway surrounding rock. This method breaks through the limitations of traditional passive support by actively regulating the stability of the rock stratum structure and stress distribution, has multiple advantages such as roof weakening, energy dissipation, and stress shielding, fundamentally improves the anti-deformation ability of the roadway, and takes into account the construction feasibility and long-term stability, providing an innovative solution for the safety control of system roadways under complex geological conditions.

[0035] The present invention has the following beneficial effects:

[0036] 1. The present invention proposes a double-layer control system of "advanced blasting roof cutting + subsequent barrier pressure relief" for determining the target horizon affecting the dynamic load intensity of the working face during the end mining period and a quantitative design method for the barrier pressure relief position. By actively constructing a stress buffer and release area, the energy dissipation of high stress inside the high-level bearing structure is realized. By implementing roof cutting pressure relief and barrier pressure relief methods on the target rock formation above the stopped coal pillar, a cavity area and a broken zone are formed, effectively releasing the stress in the rock formation, reducing the transfer of high stress to the working face and the system roadway, effectively preventing the severe deformation of the system roadway, and improving the safety of the mine;

[0037] 2. Through the synergistic effect of the first blasting roof cutting hole and the second blasting barrier pressure relief hole, the high stress in the high-level bearing layer is concentrated between the two roof cuttings, preventing the continuous disturbance of the accessory load and bending moment generated by the advanced abutment stress of the working face and the fracture of the high-level rock formation to the system roadway, blocking the transfer of high stress to the system roadway, and ensuring the stability of the surrounding rock of the system roadway. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a mechanical model diagram of the bearing arch structure of the present invention;

[0039] Figure 2 It is a schematic diagram of the effect of finally forming a stress concentration area of the present invention;

[0040] Figure 3 It is a schematic diagram of the drilling layout of the first blasting roof cutting hole and the second barrier pressure relief hole of the present invention;

[0041] Figure 4 It is a layout diagram of the first roof cutting blasting hole of the working face of the present invention;

[0042] Figure 5 It is a schematic diagram of the comparison of the advanced abutment stress curves with and without barrier pressure relief conditions of the working face rock formation of the present invention;

[0043] Figure 6 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] The present invention will be further described in detail below in conjunction with the drawings and specific preferred embodiments.

[0045] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second", etc. do not represent the importance of the components, so it cannot be understood as a limitation to the present invention. The specific dimensions adopted in this embodiment are only for illustrating the technical solution by way of example and do not limit the protection scope of the present invention.

[0046] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 shown, a method for the cutting-resistance weakening mechanism of the working face roof and the control of the surrounding rock of the system roadway includes the following steps:

[0047] Includes the following steps:

[0048] S1: Based on the mechanical model of the overlying rock bearing arch, calculate the bearing arch span b and height h that affect the caving characteristics of the working face roof, and determine the position of the target rock stratum;

[0049] S2: Arrange the first blasting roof cutting hole in front of the working face stop line to prevent the occurrence of a large-span cantilever structure on the working face;

[0050] S3: Arrange the second blasting blocking and pressure relief hole in front of the protected system roadway to block the transmission of high stress and additional loads generated by the working face to the system roadway through the upper rock stratum;

[0051] S4: Through the coordinated action of multiple drill holes, concentrate the high stress of the working face between the working face and the protected system roadway.

[0052] Among them,

[0053] Step S1: Based on the mechanical model of the overlying rock bearing arch, calculate the bearing arch span and height of the target rock stratum, and determine the position of the target rock stratum;

[0054] First, use the mechanical model of the overlying rock bearing arch to infer the distribution position of the overlying rock bearing arch above the working face during the working face advancement process, and calculate the bearing arch span b and height h. These parameters determine the position of the blasting roof cutting and pressure relief.

[0055] According to the mechanical model, the calculation of the bearing arch span needs to consider factors such as the working face length, overlying rock thickness, rock stratum properties, and the dip angle of the coal seam. Through the above parameters, the position of the target rock stratum is deduced and the specific position of the blasting operation is confirmed.

[0056] Step S2: Determine the stop position of the working face and arrange the first roof cutting blasting holes near the stop line on the working face (e.g., 10 meters away from the stop line).

[0057] Arrange the first roof cutting blasting holes 10 meters behind the stop line. The aperture of the blasting holes is set to 113 mm, and the hole bottom spacing is about 6 - 8 m. The directional cumulative blasting technology is adopted to ensure that the cracks expand along the designed direction after blasting, cut off the target rock stratum, and prevent the formation of a large-span cantilever structure of the roof during the last mining period of the working face.

[0058] Step S3: Arrange the second blasting barrier and pressure relief holes 20 - 30 m in front of the roadway of the protected system to prevent the high stress generated on the working face from being transmitted to the system roadway.

[0059] Arrange the second barrier line drilling holes 25 meters ahead of the stop line. The aperture is set to 113 mm, and the directional cumulative blasting technology is used to form a stable barrier zone to prevent the transmission of high stress to the working face and the system roadway. Through this measure, the influence of high stress on the system roadway is effectively reduced, and large deformation of the system roadway is prevented.

[0060] The arrangement of the second barrier line can accurately control the range and depth of the high stress area, ensure the safety of miners and equipment, and improve the overall stability of the mine.

[0061] Step S4: Through the coordinated action of multiple drilling holes, concentrate the high stress on the working face between the working face and the roadway of the protected system.

[0062] As Figure 1 and Figure 2 shown, simplify the bearing arch of the overlying rock of the working face into a three-hinged arch structure, where the arch height is h, the span is b, the length of the working face is l, the horizontal distance between the arch foot and the roadway side is a, and the coal seam thickness is m.

[0063] Due to the symmetric model, analyze one side. The upper part of the arch is uniformly distributed load q, the horizontal tangential support force at the arch crown is T, and the arch foot reactions are P and N.

[0064] Assume that the three-hinged arch is in a stable state without bending moment, then from the force system balance, we can get:

[0065]

[0066] P = T

[0067]

[0068] Where:

[0069] P = Nf

[0070] In the formula, f is the friction coefficient (refer to the rock strength coefficient). To ensure that the arch has sufficient stability in the horizontal direction, T must be less than P, and the safety factor is 2. Combining the above formulas, we can get

[0071] T=2Nf

[0072] From any point (x, y) on the pressure arch, the axis equation can be obtained as

[0073]

[0074] The angle between the crack sliding surface of the coal wall in the working face and the side of the coal wall at the bottom of the goaf is θ, which is obtained from the active rock mass pressure theory:

[0075]

[0076] In the formula, —Internal friction angle of overlying rock.

[0077] Combining the above formulas, the span b and height h of the pressure arch can be expressed as:

[0078]

[0079] Combined with the working face related parameters and the pressure arch mechanical model analysis: working face length l = 190m, average thickness of weak rock layer m = 1.6m, overburden internal friction angle The value of f is 2 to 2.5. Substituting it into the formula, the span b of the overburden pressure arch of the working face is 191.7m and the height h is 38.3 to 47.9m.

[0080] Based on theoretical calculations, the distribution of the pressure arch in the overlying rock during the advancement of the working face was inferred. It was determined that the location of the blasting and top-cutting drilling holes for the working face should be arranged in the 8.0m fine sandstone overlying the charcoal sandstone. The pressure arch was cut off by concentrated energy blasting, causing the high-stress area to shift above the roof, forming a larger bearing range, thereby reducing the pressure on the uphill and downhill mining areas.

[0081] like Figure 3 , Figure 4 and Figure 5, the present invention realizes the weakening of the roof cantilever structure and the control of surrounding rock stability by scientifically designing the parameters of the roof cutting blasting holes and the shaped charge blasting technology, combined with the front and rear coordinated arrangement of the roof cutting line and the barrier line. In the specific implementation, first, a first roof cutting line is arranged at a distance of 8 - 10 m near the working face stop line. Twelve roof cutting blasting holes (B1 - B12) are arranged on the roof of the machine roadway, and the bottom spacing of the roof cutting blasting holes is 6 - 8 m. Then, twelve roof cutting blasting holes (A1 - A12) are arranged on the roof of the air roadway, and the bottom spacing of the roof cutting blasting holes is 6 - 8 m. The roof cutting blasting holes adopt a hole diameter of 113 mm, and the drilling depth penetrates the entire thickness of the target rock layer. After precise construction by a hydraulic drill, shaped charge blasting cartridges are installed. The shaped charge blasting technology is based on the Munroe effect and uses a special cartridge of Φ35×300 mm. The direction of the shaped charge groove is perpendicular to the rock cutting surface, and the single - hole charge amount is 3 kg / m. After detonation, an initial fracture and fragmentation zone with a width of 0.5 - 1 m is formed. Under the action of mining stress, the blasting cracks penetrate to form a continuous surface, cutting off the roof cantilever structure. Then, a second barrier relief hole is arranged 20 - 30 m in front of the protected system roadway. After blasting, the residual stress area is cut off for the second time, and the layout parameters are the same as those of the first blasting roof cutting holes. Concentrated blasting forms a cavity area to absorb the dynamic / static stress energy and block the transmission of high stress to the system roadway. Through parameter optimization, directional blasting, and multi - channel coordinated action, the present invention realizes the efficient weakening of the roof and the control of surrounding rock stability, with both safety and economy, providing a reliable solution for mine exploitation under complex geological conditions.

[0082] Working principle: First, by establishing a mechanical model of the overlying rock bearing arch, calculate the arch - span characteristics and slip boundaries of the key rock layers to accurately locate the target rock layer affecting roof caving; subsequently, arrange directional shaped charge blasting roof cutting holes behind the stop line to cut off the rock layer continuity to eliminate the formation conditions of the large - span cantilever structure and block the transmission path of the additional load of the high - level rock layer; at the same time, implement fan - shaped deep - hole barrier blasting in front of the protected roadway to form a mechanical barrier composed of a fragmentation zone and a cavity area to absorb and attenuate the transmission energy of the dynamic and static stress waves; finally, through the coordinated action of front roof cutting and rear barrier, lock the advanced abutment stress and high - level fracture energy of the working face in the intermediate area formed by the two blasts, promote the stress field to migrate and close to the goaf side, block the propagation path of high stress to the system roadway, realize the coordinated control of the redistribution of surrounding rock stress and roadway stability, effectively avoid the formation of a large - span cantilever structure, reduce the peak value and range of the additional stress field, and block the downward transmission path of high stress inside the high - level bearing structure, thus ensuring the stability of the surrounding rock of the protected system roadway.

[0083] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above - mentioned embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A method for cutting-blocking weakening mechanism of working face roof and surrounding rock control of system roadway, characterized by: The following steps are involved: S1: Based on the mechanical model of the overburden pressure arch, calculate the pressure arch span b and height h of the target rock layer that affects the collapse characteristics of the roof of the working face, and determine the location of the target rock layer; S2: Arrange the first blasting top cutting hole near the stop mining line of the working face to prevent the appearance of a large-span cantilever structure on the working face; S3: After the mining line is stopped, a second blasting barrier pressure relief hole is arranged in front of the protected system tunnel to prevent the high stress and additional load generated by the working face from being transmitted to the system tunnel through the high rock layer; S4: Through the synergistic effect of multiple drillings, the high stress of the working face is concentrated between the working face and the protected system tunnel.

2. The method for the cutting-resistance weakening mechanism of the working face roof and the control of the surrounding rock of the system roadway according to claim 1, characterized in that: In step S1, the force system balance yields: P = T; in: P=Nf In the formula, f is the solidity coefficient of the overburden, the arch height is h, the span is b, the length of the working face is l, q is the load, T is the horizontal tangential support force of the arch top, and P and N are the reaction forces at the arch foot; Let the safety factor be 2, and combine the above formulas to get: T=2Nf From any point (x, y) on the pressure arch, the axis equation can be obtained as: The angle between the crack sliding surface of the coal wall in the working face and the side of the coal wall at the bottom of the goaf is θ, which is obtained from the active rock mass pressure theory: In the formula, — the angle of internal friction of the overlying strata; Combining the above formulas, the span b and height h of the pressure arch can be expressed as:

3. The method for weakening the cutting and resistance of the working face roof and controlling the surrounding rock of the system roadway according to claim 2, characterized in that: In step S2, the first blasting top cutting holes are arranged on the working face, and the blasting top cutting holes are arranged in the stop mining coal pillar area 8-10m behind the stop mining line.

4. The method for controlling the surrounding rock of the working face roof cutting-resistance weakening mechanism and the system roadway according to claim 2, characterized in that: Directed focused energy blasting technology is used to cut off the target rock layer in time to prevent the formation of a large-span cantilever structure, so that the surrounding rock stress field in the area above the suspended coal pillar shows significant unevenness and centralization characteristics. The first blasting top cutting hole is arranged behind the suspended mining line to fundamentally reduce the additional load and bending moment of the high-position rock layer on the cantilever structure of the target rock layer.

5. The method for controlling the surrounding rock of the working face roof cutting-resistance weakening mechanism and system roadway according to claim 3, characterized in that: Blasting barrier and pressure relief holes are arranged on the second barrier line. The barrier and pressure relief holes are arranged obliquely upward on both sides of the working face and are fan-shaped as a whole. The blasting effect of the barrier and pressure relief holes forms a continuous cutting surface on the section, which is located in the coal pillar area where mining is stopped 20-30m in front of the protected system tunnel.

6. The method for controlling the surrounding rock of the working face roof cutting-resistance weakening mechanism and the system roadway according to claim 3, wherein: In step S3, the second blasting barrier pressure relief hole is arranged in front of the protected system tunnel. After blasting, a broken zone and a cavity area are formed to prevent the high stress generated by the working face from being transmitted to the system tunnel.

7. The method for the cutting-resistance weakening mechanism of the working face roof and the control of the surrounding rock of the system roadway according to claim 4, characterized in that: The first top cutting blasting hole is arranged behind the stop mining line of the working face, and the barrier pressure relief hole is arranged in front of the protected tunnel, both of which are located above the stop mining coal pillar area.

8. The method for the cutting-resistance weakening mechanism of the working face roof and the control of the surrounding rock of the system roadway according to claim 4, characterized in that: The first top-cutting blasting hole cuts off the target rock layer to prevent the appearance of a large-span cantilever structure of the roof during the final mining period of the working face, and reduces the peak value and range of the additional stress on the roof; the second barrier and pressure relief hole is further blasted through the high-position hole to form a cavity area and a broken zone structure in the target area, effectively absorbing the dynamic and static stress energy transmitted downward by the high-position bearing structure, thereby reducing the disturbance to the protected tunnel, through the synergistic effect of the first blasting top-cutting hole and the second blasting barrier and pressure relief hole; Make the high stress in the high-level bearing layer concentrate between two roof cutting positions, prevent the continuous disturbance of the accessory load and bending moment generated by the advanced abutment stress of the working face and the fracture of the high-level rock stratum to the system roadway, prevent the high stress from transmitting to the system roadway, and ensure the surrounding rock stability of the system roadway.

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