Close-distance coal seam broken roof cutting entry retaining method

Abstract

The invention belongs to the technical field of coal mine safety mining, and discloses a close-range coal seam broken roof cutting entry retaining method which comprises the following steps: S1, injecting quick-setting slurry into a roof and two sides of a roadway; s2, a plurality of rows of anchor cable sets are arranged on the lower end face of the roadway top plate, and any row of anchor cable sets comprise constant-resistance anchor cables arranged in the axial direction of the roadway; s3, a top plate advanced kerf is formed in the working face top plate for blasting, and the working face top plate is cut off within the local range; s4, waste rock blocking supporting is carried out on the area where the roadway is blasted; according to the method, the expansive gel filling material is injected into the broken roof of the close-range coal seam, so that on one hand, the stability of the broken roof is improved, on the other hand, the buffering effect can be achieved in the pressing process, and the safety supporting effect during mining of the broken roof of the close-range coal seam is improved; roof caving and air leakage of the roof-cutting roadway caused by roof rock stratum breaking are effectively avoided, rapid roof-cutting roadway forming of the roadway is guaranteed, and use is safe.

Description

Technical Field

[0001] The invention belongs to the technical field of safe mining of coal mines, and in particular relates to a method for cutting and retaining a roadway through a broken roof of a close-range coal seam. Background Art

[0002] As the depth of coal mining continues to increase, the gas content and gas pressure of coal seams continue to increase, and the danger of coal and gas outbursts is becoming more and more serious. In the coal mining process, it is often necessary to leave coal pillars to support the roof of the mine and protect the tunnels along the goaf from being crushed. However, the mining method of leaving coal pillars is not suitable for situations where the bearing capacity of the foundation is poor, and leaving coal pillars is also prone to high mining ratios, low production efficiency, and serious waste of resources. In addition, leaving coal pillars is also prone to safety hazards such as gas surges and air leakage in the goaf. Therefore, in recent years, attempts have been made to mine coal seams by cutting the top and leaving the goaf.

[0003] The method of cutting the top and leaving the lane refers to the technology of strengthening and supporting the mining lane, and then directional pre-splitting blasting is carried out on the side of the lane where the goaf will be formed, and the roof is cut according to the designed position. After the cutting is completed, with the mining of the coal seam on the working face, under the action of the mine pressure, the roof of the goaf collapses along the pre-splitting cut to form the lane wall, and a new lane is automatically formed by using part of the space and support of the original lane as the mining lane of the next working face. The method of cutting the top and leaving the lane does not leave a section of coal pillars, which greatly improves the recovery rate of coal resources. At the same time, each mining face excavates one less mining lane, which greatly reduces the coal mine's 10,000-ton excavation rate.

[0004] Although the existing technology of roof cutting and lane retention has been successfully applied in China, it is rarely used under the condition of close-distance coal seams. Close-distance coal seams refer to coal seams with very close interlayer spacing and significant mutual influence during mining. In addition, in the process of re-mining coal seams, some mining lanes need to pass through old goafs. Affected by the old goafs and mining dynamic pressure, these mining lanes will experience roof separation, caving, collapse, and two-side surrounding rock crushing, spalling and other serious accidents. Conventional anchor net cable support cannot form a whole with the surrounding rock, so there is a problem of poor support effect. Therefore, a method of roof cutting and lane retention in close-distance coal seam crushing is proposed. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for cutting off the roof and leaving a lane in a close-range coal seam, which solves the problems in the prior art of difficulty in leaving a lower working face mining lane and poor support effect when downward mining in a close-range coal seam.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for cutting off the top of a coal seam with broken roof and leaving a lane in a close distance comprises the following steps:

[0008] S1: Inject quick-setting slurry into the roof and two sides of the tunnel;

[0009] S2: A plurality of rows of anchor cable groups are provided on the lower end surface of the top plate of the tunnel, and any row of anchor cable groups includes constant resistance anchor cables arranged along the axial direction of the tunnel;

[0010] S3: Open an advance slit on the roof of the working face for blasting, and cut off the roof of the working face in a local area;

[0011] S4: Carry out rock support in the area after tunnel blasting;

[0012] Inject quick-setting slurry into the top plate and two sides of the tunnel. The specific steps are as follows:

[0013] S1.1: According to the cross-sectional characteristics and roof conditions of the tunnel, multiple roof grouting holes are arranged on the tunnel roof, and quick-setting slurry is injected into the roof grouting holes. After the quick-setting slurry is injected into the roof grouting holes, a stable roof reinforcement arch is formed;

[0014] S1.2: According to the cross-sectional characteristics of the tunnel and the development characteristics of the cracks on both sides, multiple grouting holes are arranged on both sides of the tunnel, and quick-setting slurry is injected into the grouting holes;

[0015] S1.3: According to the on-site implementation conditions, select one or two roof grouting holes for multiple hole expansion to form filling grouting holes, and inject filling materials into the goaf above the reinforced roof;

[0016] The cross-sectional characteristics include the cross-sectional shape and size of the roadway;

[0017] Roof conditions refer to whether there are broken zones and goafs above the roof;

[0018] The developmental characteristics of the two gang fissures refer to the expansion and penetration of the fissures;

[0019] On-site implementation conditions refer to the reinforcement scope of the reinforced top slab;

[0020] The filling material is an expansive cementitious material or a cement-fly ash material;

[0021] The upper ends of the constant resistance anchor cables penetrate the direct top and extend to the inside of the basic top. The lower ends of the constant resistance anchor cables are exposed below the direct top, and the exposed length of the constant resistance anchor cables is 250mm to 300mm. The preload force of the constant resistance anchor cables is greater than or equal to 250kN.

[0022] The constant resistance device for constant resistance anchor cable is 500mm long, 79mm in outer diameter, with a maximum allowable deformation of 350mm, a constant resistance value of 30±2t, and a preload greater than or equal to 250kN.

[0023] The anchor cable groups are arranged in three rows, and the three rows of anchor cable groups are distributed from the advanced slit close to the top plate to the advanced slit far away from the top plate;

[0024] The distance between each constant resistance anchor cable in a row of anchor cables close to the advanced slit of the top plate and the advanced slit of the top plate is 500mm, and the spacing between two adjacent constant resistance anchor cables is 900mm;

[0025] The distance between each constant resistance anchor cable in the middle row of anchor cables and the advanced slit of the top plate is 1500mm, and the distance between two adjacent constant resistance anchor cables is 1800mm;

[0026] The distance between each constant resistance anchor cable of a row of anchor cables far away from the advanced slit of the top plate and the advanced slit of the top plate is 2500mm, and the spacing between two adjacent constant resistance anchor cables is 2700mm;

[0027] A row of anchor cable groups close to the advanced cut of the top plate is connected to a row of anchor cable groups in the middle by a reinforced ladder beam, and two adjacent ladder beams are connected by stubble.

[0028] The constant resistance anchor cables in the row of anchor cable groups far away from the advanced slit of the top plate and the middle row of anchor cable groups are used in conjunction with the anchor cable tray;

[0029] The steel ladder beam is welded with φ18mm round steel, and the specifications of the ladder beam are 3500mm×120mm or 2000mm×120mm or 3100mm×120mm;

[0030] The constant resistance anchor cable should be arranged perpendicular to the tunnel roof or tunnel contour line, and the maximum allowable angle deviation is 2°;

[0031] Carry out advanced slit blasting on the top of the working face to cut off the top of the working face in a local area. The specific steps are as follows:

[0032] S3.1: A roof advance cut is set on the roof along the direction of the roadway, and a row of evenly distributed pre-splitting boreholes are opened along the roof advance cut. The distance between the pre-splitting borehole and the roadway mining wall is 200mm, the depth of the pre-splitting borehole is 5.5-10m, the spacing between two adjacent pre-splitting boreholes is 500mm, and the angle between the pre-splitting borehole and the plumb line is 12°;

[0033] S3.2: The shaped energy blasting adopts coal mine grade 3 water gel explosive, the explosive roll specification is Φ32×200mm / roll, and the length of a single shaped energy tube is 1500mm;

[0034] Multiple sections of focused tubes are installed in any pre-splitting borehole, each section of the focused tube is continuously filled with multiple explosive rolls, the explosive rolls between adjacent focused tubes are separated by air, and a detonator is installed in the lowest explosive roll of each section of the focused tube;

[0035] The detonators in the same pre-splitting borehole are connected in series and detonated in the forward direction;

[0036] Each pre-splitting borehole is connected in series and blasted continuously at one time;

[0037] Adjust the cutting direction of the energy-gathering tube to be the same as the advanced cutting direction of the roof, and seal the pre-splitting borehole with taphole mud;

[0038] Carry out rock support in the area after tunnel blasting. The specific steps are as follows:

[0039] S4.1: Steel mesh is laid on the roof and side of the tunnel after blasting. U-shaped steel is used to build rock retaining support close to the steel mesh on the side of the roof seam. The U-shaped steel is close to the inner side of the roof advance seam. A hydraulic unit is set at a position 150-400mm away from the roof advance seam in the tunnel. The liquid unit cooperates with the hinged top beam to support the U-shaped steel. The rock retaining support construction of each shift is closely followed by the large column of the comprehensive mining support.

[0040] S4.2: The position of the comprehensive mining support is 300 to 500 mm inside the advanced cutting seam of the roof, and the spacing between U-shaped steels is 500 mm.

[0041] Beneficial effects of the present invention:

[0042] 1. The present invention injects expansive gelling filling materials into the broken roof of the close-range coal seam, which improves the stability of the broken roof on the one hand, and plays a buffering role in the pressure process on the other hand, thereby improving the effect of safe support during the mining of the broken roof of the close-range coal seam, effectively avoiding the roof collapse and air leakage of the roadway caused by the broken roof rock layer, and ensuring the rapid cutting of the roadway into a roadway and safe use;

[0043] 2. The present invention has a good control effect on the surrounding rock of the broken roof tunnel, and is simple to operate, greatly reducing the restrictions on use, improving efficiency and benefits;

[0044] 3. The present invention sets a constant resistance anchor cable, which has good anti-impact deformation ability after the surrounding rock is deformed, can absorb impact energy in a very short time and keep the system stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 It is a schematic diagram of the working face mining process of the present invention;

[0047] Figure 2It is a structural schematic diagram of the constant resistance anchor cable of the present invention;

[0048] Figure 3 It is a schematic diagram of the structure of the hydraulic unit of the present invention;

[0049] Figure 4 It is a schematic diagram of the goaf area and hydraulic monomer of the present invention;

[0050] Figure 5 It is a structural schematic diagram of the steel mesh of the present invention;

[0051] Figure 6 It is a schematic diagram of the structure of the top plate grouting hole of the present invention.

[0052] In the figure: 1. Constant resistance anchor cable; 2. Basic roof; 3. Direct roof; 4. Lower section working face; 5. Tunnel; 6. Upper coal seam; 7. Lower coal seam; 8. Upper section working face; 9. Roof advance cutting; 10. Hydraulic unit; 11. Goaf; 12. Cut-top tunnel; 13. Grouting hole in the side; 14. Grouting hole in the roof; 15. Tunnel surrounding rock. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] like Figures 1 to 6 As shown, the present invention provides a method for cutting the top of a coal seam with broken roof and retaining lanes at a close distance, comprising the following steps:

[0055] S1: inject quick-setting slurry into the roof and two sides of tunnel 5;

[0056] S2: A plurality of rows of anchor cable groups are provided on the lower end surface of the roof of the tunnel 5, and any row of anchor cable groups includes a constant resistance anchor cable 1 arranged axially along the tunnel 5;

[0057] S3: Opening a roof advance cut 9 on the roof of the working face for blasting, and cutting off the roof of the working face in a local area;

[0058] S4: Carry out rock support in the area after blasting of tunnel 5;

[0059] Quick-setting slurry is injected into the roof and two sides of tunnel 5. The specific steps are as follows:

[0060] S1.1: According to the cross-sectional characteristics and roof conditions of the tunnel 5, a plurality of roof grouting holes 14 are arranged on the roof of the tunnel 5, and quick-setting slurry is injected into the roof grouting holes 14. After the quick-setting slurry is injected into the roof grouting holes 14, a stable roof reinforcement arch is formed;

[0061] S1.2: According to the cross-sectional characteristics of the tunnel 5 and the development characteristics of the cracks on both sides, a plurality of grouting holes 13 are arranged on both sides of the tunnel 5, and quick-setting slurry is injected into the grouting holes 13;

[0062] S1.3: According to the on-site implementation conditions, select one or two roof grouting holes 14 for multiple hole expansion to form filling grouting holes, and inject filling materials into the goaf above the reinforced roof;

[0063] After high-strength quick-setting slurry is injected into the roof grouting hole 14, a stable roof reinforcement arch is formed. After the overburden movement in the goaf 11 gradually becomes stable, the sidewall of the remaining roadway is sprayed to achieve the purpose of sealing the goaf 11, preventing air leakage from the roadway 5 to the goaf 11, and preventing gas accumulation and spontaneous combustion of coal in the goaf 11;

[0064] Since the stone support is set in the spare part of the supporting structure, some of its positions may have poor stability and become loose or fall under the action of the collapsed top plate. At this time, the damaged position can be cleaned, and then the damaged position can be reinforced by hanging mesh and spraying concrete, which is conducive to ensuring the structural stability of the tunnel 5, thereby preventing the collapsed rock layer from blocking the tunnel 5, and also making it possible to transfer related equipment or personnel more smoothly and quickly when mining the working face of the lower section, thereby helping to improve the mining efficiency;

[0065] After the filling material is injected into the goaf, it can play a role of buffering and stress transfer during the process of roof compression.

[0066] The cross-sectional characteristics include the cross-sectional shape and size of the tunnel 5;

[0067] Roof conditions refer to whether there are broken zones and goaf areas above the roof11;

[0068] The developmental characteristics of the two gang fissures refer to the expansion and penetration of the fissures;

[0069] On-site implementation conditions refer to the reinforcement scope of the reinforced top slab;

[0070] In the present embodiment, the reinforcement range of the reinforced top plate is relatively large, so two top plate grouting holes 14 are selected for multiple hole expansion and filling of the top plate grouting holes 14. In other embodiments, when the reinforcement range of the reinforced top plate is relatively small, one top plate grouting hole 14 is selected for multiple hole expansion and filling of the top plate grouting hole 14.

[0071] The filling material is an expansive cementitious material or a cement-fly ash material; when the expansive cementitious material or the cement-fly ash material is injected into the goaf, the filling material can play a role in buffering and stress transmission during the process of roof pressure.

[0072] The upper ends of the constant resistance anchor cables 1 penetrate the direct top 2 and extend to the inside of the basic top 3. The lower ends of the constant resistance anchor cables 1 are exposed below the direct top 2. The exposed length of the constant resistance anchor cables 1 is 250 mm to 300 mm. The preload force of the constant resistance anchor cables 1 is greater than or equal to 250 kN.

[0073] The constant resistance device of constant resistance anchor cable 1 is 500mm long, 79mm in outer diameter, 350mm in maximum allowable deformation, 30±2t in constant resistance, and the preload is greater than or equal to 250kN;

[0074] Taking the production geological data of a certain mine as an example, the upper coal seam 6 and the lower coal seam 7 of a certain mine are close coal seams. The thickness of the upper coal seam 6 above the lower coal seam 7 is mostly 1.1m to 1.9m. The upper coal seam 6 is 3.3m to 6.5m away from the roof of the working face tunnel 5 of the lower coal seam 7. When the working face of the lower coal seam 7 is mined, the roof is prone to plastic deformation and interlayer sliding. The upper coal seam 6 is a Class II spontaneous combustion coal seam. After the working face of the lower coal seam 7 is mined, the overlying upper coal seam 6 may fall into the goaf 11 of the lower coal seam 7 in a broken state, posing a risk of spontaneous combustion.

[0075] Among them, a certain working face of the lower coal seam 7 is located in the middle of the left wing of a mining area. The working face has a strike length of 830m and a width of 182m. The buried depth of the ventilation lane of the working face is between 381 and 432m. The top cutting and pressure relief self-forming lane technology is adopted. After the lane is left, it is used as the machine lane of the next section working face of the lower coal seam 7. While recovering the coal pillar, one less lane 5 is excavated. In the present invention, the constant resistance anchor cable 1 is rooted in the broken goaf area of ​​the upper coal seam 6, not less than 1000mm.

[0076] The anchor cable groups are arranged in three rows, and the three rows of anchor cable groups are distributed from the direction close to the top plate advance cut slit 9 to the direction far from the top plate advance cut slit 9;

[0077] The distance between each constant resistance anchor cable 1 in a row of anchor cable groups close to the advanced slit 9 of the top plate and the advanced slit 9 of the top plate is 500 mm, and the spacing between two adjacent constant resistance anchor cables 1 is 900 mm;

[0078] The distance between each constant resistance anchor cable 1 in the middle row of anchor cable groups and the top plate advance cut slit 9 is 1500mm, and the spacing between two adjacent constant resistance anchor cables 1 is 1800mm;

[0079] The distance between each constant resistance anchor cable 1 of a row of anchor cables far away from the top plate advance cut slit 9 and the top plate advance cut slit 9 is 2500mm, and the spacing between two adjacent constant resistance anchor cables 1 is 2700mm;

[0080] Taking the above-mentioned mine production geological data as an example, three rows of anchor cable groups are arranged from left to right on the roof of tunnel 5 of a certain working face.

[0081] A row of anchor cable groups close to the advanced cut seam 9 of the top plate is connected to a row of anchor cable groups in the middle by a steel ladder beam, and two adjacent ladder beams are connected by a stubble method;

[0082] The anchor cable group in a row away from the advanced cut slit 9 of the top plate and the constant resistance anchor cables 1 in the middle row of anchor cable groups are used in conjunction with the anchor cable tray;

[0083] Steel ladder beam Round steel welding, ladder beam specifications 3500mm×120mm or 2000mm×120mm or 3100mm×120mm;

[0084] The anchor cable tray is made of 18mm thick flat steel plate. The tray specifications are length × width × thickness = 300mm × 300mm × 18mm. Round hole.

[0085] The constant resistance anchor cable 1 should be arranged perpendicular to the top plate of the tunnel 5 or the contour line of the tunnel 5, and the maximum angle deviation allowed is 2°;

[0086] Among them, the exposed length of the constant resistance anchor cable 1 (outside the lock) is 150mm~300mm, the preload force is 250~300kN, and the YCD-300 tensioning jack is used for tensioning, and the corresponding tensioning value is 47.6MPa~57.1MPa. The YCD22-520 tensioning jack is used for tensioning, and the corresponding tensioning value is 33.1MPa~39.7MPa; the constant resistance anchor cable 1 should be arranged perpendicular to the top plate of tunnel 5 or the contour line of tunnel 5, and the allowable angle deviation is -2°~2°.

[0087] The working face roof is advanced cut 9 blasted to cut off the working face roof in a local area. The specific steps are as follows:

[0088] S3.1: A roof advance cut 9 is set on the roof along the direction of the roadway 5, and a row of multiple pre-splitting boreholes are evenly distributed along the roof advance cut 9. The distance between the pre-splitting borehole and the mining wall of the roadway 5 is 200mm, the depth of the pre-splitting borehole is 5.5-10m, the spacing between two adjacent pre-splitting boreholes is 500mm, and the angle between the pre-splitting borehole and the plumb line is 12°;

[0089] S3.2: The shaped energy blasting adopts coal mine grade 3 water gel explosive, the explosive roll specification is Φ32×200mm / roll, and the length of a single shaped energy tube is 1500mm;

[0090] Multiple sections of focused tubes are installed in any pre-splitting borehole, each section of the focused tube is continuously filled with multiple explosive rolls, the explosive rolls between adjacent focused tubes are separated by air, and a detonator is installed in the lowest explosive roll of each section of the focused tube;

[0091] The detonators in the same pre-splitting borehole are connected in series and detonated in the forward direction;

[0092] Each pre-splitting borehole is connected in series and blasted continuously at one time;

[0093] Adjust the energy-gathering tube cutting direction to be the same as the roof advance cutting direction 9, and seal the pre-splitting borehole with taphole mud;

[0094] Taking the above mine production geological data as an example, the depth of the pre-splitting borehole is based on the bottom plate of the upper coal seam 6, and the hole depth is not less than 5.5m, the hole spacing is 500mm, and the angle between the borehole and the plumb line is 12° (biased towards the mining side);

[0095] Before sealing the hole with taphole mud, adjust the cutting direction of the energy-gathering tube to be consistent with the advanced cutting direction of the top plate 9;

[0096] For connected-line blasting, after the construction workers have installed the blast holes required for the blasting on duty according to the design requirements, the blaster will be responsible for connecting the exposed foot lines of each hole in series. Then, blasting will be carried out in accordance with the requirements of the technical measures for safety in blasting construction, including forward blasting, series blasting, parallel blasting inspection, and hanging of hole mouth signs.

[0097] The area after blasting in tunnel 5 is supported by rock blocking. The specific steps are as follows:

[0098] S4.1: Steel mesh is laid on the roof and side of the tunnel 5 after blasting. U-shaped steel is used to close the steel mesh to construct the rock blocking support at the side of the roof cut. The U-shaped steel is close to the inner side of the roof advance cut 9. A hydraulic unit 10 is set at a position 150-400mm away from the roof advance cut 9 in the tunnel 5. The liquid unit cooperates with the hinged top beam to support the U-shaped steel. The rock blocking support construction of each shift is closely followed by the large column of the comprehensive mining support.

[0099] S4.2: The position of the fully mechanized mining support is 300-500mm away from the front cutting seam of the roof, and the spacing between U-shaped steels is 500mm;

[0100] U-shaped steel is used to construct the rock retaining support close to the steel mesh at the side of the advanced cutting slit 9 of the roof. The U-shaped steel is close to the inner side of the advanced cutting slit 9 of the roof. The hydraulic unit 10 is matched with the hinged top beam and placed outside the advanced cutting slit 9 of the roof. The rock retaining support construction of each shift closely follows the top beam of the comprehensive mining support. The hydraulic unit 10 is matched with the hinged top beam and placed outside the advanced cutting slit 9 of the roof. The distance from the advanced cutting slit 9 of the roof is 200mm (deviation -50mm~+200mm). The rock retaining support construction of each shift closely follows the large column of the comprehensive mining support.

[0101] The position of the comprehensive mining support is 300 to 500mm away from the front cutting seam 9 of the roof; the spacing between U-shaped steels is 500mm. For the side pressure and super-high section, the U-shaped shed is reduced to 300mm (net spacing), and 3-4 pairs of U-shaped cards can be used; the adjacent U-shaped steels are connected with cable ties and transverse pull rods. The pull rods are made of δ10mm steel plates, and the pre-tightening force of the cable ties bolts is 60N·m to 90N·m; the distance between the cable ties and the upper and lower ends of the U-shaped steel stub section is not more than 400mm; the stub between the steel meshes is not less than 200mm, and two groups are used for each shed (one to two rows of pull rods can be added when the tunnel 5 is super-high), the stub between the steel meshes is not less than 200mm, and they are tied tightly with two rows of double-strand iron wires of not less than 12#, and the interval between the iron wire bundling is not more than 200mm.

[0102] Considering that the lower coal seam 7 needs to be divided into several sections when it is mined, when the upper section working face 8 is mined, the lower section working face 4 needs to be mined, and the time interval between the two becomes the main key affecting economic benefits. By arranging blasting holes in the tunnel 5 that needs to be top-cut under the goaf 11 of the upper coal seam 6 at a close distance, close to the goaf 11 side, the top plate of the goaf 11 is collapsed along the pre-crack position by blasting to automatically form a top-cut tunnel 12. This tunnel 5 serves as the tunnel 5 of the lower section working face 4, reducing the stress on the top plate above the lower section working face 4, achieving the stability of the tunnel surrounding rock 15 along the goaf, that is, achieving the purpose of maintaining the stability of the top-cut tunnel 12.

[0103] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0104] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for cutting the roof and leaving lanes in a close-range coal seam by breaking the roof, characterized in that: The following steps are involved: S1: injecting quick-setting slurry into the roof and two sides of the tunnel (5); S2: A plurality of rows of anchor cable groups are provided on the lower end surface of the top plate of the tunnel (5), and each row of the anchor cable groups includes a constant resistance anchor cable (1) arranged along the axial direction of the tunnel (5); S3: Opening a roof advance cut (9) on the top plate of the working face for blasting, thereby cutting off the top plate of the working face in a local area; S4: Carry out rock support in the area after blasting of the tunnel (5).

2. The method for cutting the roof and leaving the lane in a close-range coal seam by breaking the roof according to claim 1 is characterized in that: Quick-setting slurry is injected into the roof and two sides of the tunnel (5), and the specific steps are as follows: S1.1: According to the cross-sectional characteristics of the tunnel (5) and the roof crushing conditions, a plurality of roof grouting holes (14) are arranged on the roof of the tunnel (5), and quick-setting slurry is injected into the roof grouting holes (14). After the quick-setting slurry is injected into the roof grouting holes (14), a stable broken roof reinforcement arch is formed; S1.2: According to the cross-sectional characteristics of the tunnel (5) and the development characteristics of the cracks on both sides, a plurality of grouting holes (13) are arranged on both sides of the tunnel (5), and quick-setting grouting liquid is injected into the grouting holes (13); S1.3: According to the on-site implementation conditions, one or two roof grouting holes (14) are selected for multiple hole expansion to form filling grouting holes, and filling materials are injected into the broken goaf above the reinforced roof structure.

3. The method for cutting and retaining lanes in a close-range coal seam by breaking the roof according to claim 2 is characterized in that: The cross-sectional characteristics include the cross-sectional shape and size of the tunnel (5); the roof condition refers to whether there are broken zones and goafs (11) above the roof; the development characteristics of the cracks on both sides refer to the expansion and penetration of the cracks; the on-site implementation conditions refer to the reinforcement range of the reinforced roof; and the close-range coal seam refers to the distance between the upper coal seam (6) and the lower coal seam (7) being less than 10m.

4. The method for cutting the roof and leaving lanes in a close-range coal seam by breaking the roof according to claim 3 is characterized in that: The filling material is an expansive cementitious material or a cement-fly ash material.

5. The method for cutting off the top of the coal seam and retaining the lane in a short distance according to claim 4 is characterized in that: The upper ends of the constant resistance anchor cables (1) penetrate the direct top (2) and extend to the inside of the basic top (3), the lower ends of the constant resistance anchor cables (1) are exposed below the direct top (2), and the exposed length of the constant resistance anchor cables (1) is 250 mm-300 mm, and the pre-tightening force of the constant resistance anchor cables (1) is equal to or greater than 250 kN; The constant resistance device of the constant resistance anchor cable (1) is 500 mm in length, 79 mm in outer diameter, 350 mm in maximum allowable deformation, 30 ± 2 t in constant resistance, and a preload equal to or greater than 250 kN.

6. The method for cutting off the top of the coal seam and retaining the lane in a short distance according to claim 5 is characterized in that: The anchor cable groups are arranged in three rows, and the three rows of anchor cable groups are distributed from the direction close to the top plate advance cut slit (9) to the direction far from the top plate advance cut slit (9); The distance between each constant resistance anchor cable (1) in a row of anchor cable groups close to the top plate advance cut (9) and the top plate advance cut (9) is 500 mm, and the spacing between two adjacent constant resistance anchor cables (1) is 900 mm; The distance between each constant resistance anchor cable (1) in the middle row of anchor cable groups and the top plate advance cut slit (9) is 1500 mm, and the spacing between two adjacent constant resistance anchor cables (1) is 1800 mm; The distance between each constant resistance anchor cable (1) of a row of anchor cables far away from the top plate advance cut slit (9) and the top plate advance cut slit (9) is 2500 mm, and the spacing between two adjacent constant resistance anchor cables (1) is 2700 mm.

7. The method for cutting off the top of the coal seam and retaining the lane in a short distance according to claim 6 is characterized in that: A row of anchor cable groups close to the advanced cut seam (9) of the top plate is connected to a row of anchor cable groups in the middle by using a steel ladder beam, and two adjacent steel ladder beams are connected by a stub method; The anchor cable group in a row away from the top plate advance cut (9) and the constant resistance anchor cables (1) in the middle row of anchor cable groups are used in conjunction with the anchor cable tray; Steel ladder beam Round steel welding, steel ladder beam specifications are 3500mm×120mm or 2000mm×120mm or 3100mm×120mm.

8. The method for cutting off the top of the coal seam and retaining the lane in a short distance according to claim 7 is characterized in that: The constant resistance anchor cable (1) should be arranged perpendicular to the top plate of the tunnel (5) or the contour line of the tunnel (5), and the maximum allowable angle deviation is 2°.

9. The method for cutting off the roof and retaining lanes in a close-range coal seam crushing according to claim 8 is characterized in that: The working face roof advance cutting blasting (9) is carried out to cut off the working face roof in a local area. The specific steps are as follows: S3.1: a roof advance cut (9) is provided on the roof along the direction of the roadway (5), and a row of multiple pre-splitting boreholes evenly distributed are opened along the roof advance cut (9), the distance between the pre-splitting borehole and the mining wall of the roadway (5) is 200 mm, the depth of the pre-splitting borehole is 5.5-10 m, the spacing between two adjacent pre-splitting boreholes is 500 mm, and the angle between the pre-splitting borehole and the plumb line is 12°; S3.2: The blasting adopts coal mine grade 3 water gel explosive, the explosive roll specification is Φ32×200mm / roll, and the length of a single energy tube is 1500mm; Multiple sections of focused tubes are installed in any pre-splitting borehole, each section of the focused tube is continuously filled with multiple explosive rolls, the explosive rolls between adjacent focused tubes are separated by air, and a detonator is installed in the lowest explosive roll of each section of the focused tube; The detonators in the same pre-splitting borehole are connected in series and detonated in the forward direction; Each pre-splitting borehole is connected in series and blasted continuously at one time; The cutting direction of the energy-gathering tube is adjusted to be consistent with the advanced cutting direction of the roof (9), and the pre-splitting borehole is sealed by taphole mud.

10. The method for cutting off the top of the coal seam and retaining the lane in a short distance according to claim 9 is characterized in that: The area after blasting of the tunnel (5) is supported by rock blocking, and the specific steps are as follows: S4.1: Steel mesh is laid on the roof and side walls of the tunnel (5) after blasting. U-shaped steel is used to close the steel mesh to construct the rock retaining support at the side wall of the roof cut. The U-shaped steel is close to the inner side of the roof advance cut (9). A hydraulic unit (10) is set at a position 150-400mm away from the roof advance cut (9) in the tunnel (5). The liquid unit cooperates with the hinged top beam to support the U-shaped steel. The rock retaining support construction is closely followed by the large column of the comprehensive mining support. S4.2: The position of the fully mechanized mining support is 300 to 500 mm inside the advanced cutting seam (9) of the roof, and the spacing between U-shaped steels is 500 mm.

Images