A method for preventing and treating a head-on leakage structure of broken coal rock mass and a construction method thereof

Abstract

The present application relates to the technical field of coal mining, in particular to the technical field of broken coal and rock mass head-on technology, and specifically relates to a structure for preventing and treating broken coal and rock mass head-on and a construction method thereof. In order to solve the defects of the existing pre-anchored adhesive material method and the small-circulation construction method, the specific structure is as follows: a row of advance holes is drilled, an advance steel pipe is inserted into the advance holes, a first support point of the advance steel pipe is formed by the other end of the advance steel pipe being located above the solid rock of the roof of the next excavation area, the end of the advance steel pipe is held and compressed by the anchor net and anchor rod to form the first support point of the advance steel pipe, and the two ends of the advance steel pipe are fixed and tightly held to the roof of the excavation area by the two support points, thereby achieving temporary advance support of the roof of the excavation area before excavation, effectively preventing and treating broken coal and rock mass head-on and leakage after excavation, and permanently supporting the top of the mined-out area after excavation is completed, and supporting the sidewall, thereby forming a permanent section of the roadway.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and particularly to the field of fractured coal and rock face technology, specifically a structure for preventing leakage at the face of fractured coal and rock and its construction method. Background Technology

[0002] When tunneling through faults, collapse columns, igneous intrusion zones, soft coal and rock strata, layered coal and rock strata, areas with well-developed joints and fissures, and fractured zones, face-bursting of the fractured coal and rock mass often occurs. Face-bursting seriously threatens the safety of workers, and handling face-bursting is extremely dangerous. Therefore, it is necessary to explore convenient, safe, and practical prevention and control methods.

[0003] Regarding the problem of head leakage, there are two existing methods to solve this problem: (1) Pre-injection of bonding materials. The specific construction method is: before excavating the next cycle range, pre-inject bonding materials such as malathion or cement water glass slurry to bond and reinforce the broken rock mass, improve the strength of the surrounding rock, and improve the stress state. Then, the rock mass is excavated in the whole section, the roof is retained and permanently supported. Although this method can effectively prevent head leakage, it is an independent process placed before excavation. It requires special materials, equipment and technical personnel, which is costly and has a complicated operation process and takes a long time. Bonding and reinforcement must be carried out once every 1-2 cycles, and materials and equipment need to be frequently transported, which affects the level of advance and efficiency improvement. The high molecular materials such as malathion generate heat, which causes the coal body to heat up and oxidize, and carbon monoxide is easily generated locally, which can easily cause workers to inhale carbon monoxide and affect their health.

[0004] (2) Sectional small-loop construction method. By excavating in sections and small loops, the area of ​​the unsupported roof after excavation is reduced, thus mitigating the degree of leakage. Its disadvantage is that it is difficult to completely prevent leakage, only to reduce the degree; moreover, a large loop is divided into multiple small loops, and each small loop is divided into several small sections. The construction of each small section requires repeated excavation, support and other procedures, which takes up time and is inefficient. Summary of the Invention

[0005] In order to solve the above-mentioned defects of the existing pre-bonding material method and the segmented small-circulation construction method, this invention provides a new structure for preventing leakage at the face of fractured coal and rock mass and its construction method.

[0006] This invention is achieved using the following technical solution:

[0007] A structure for preventing leakage at the face of fractured coal and rock masses includes a row of evenly distributed advance holes along the width of the roadway, drilled from below the roof of the face section of the prepared excavation area toward above the roof of the next excavation area (above the roof is solid rock mass), and advance steel pipes adapted to the advance holes with their heads inserted into the bottom of the advance holes. (From this, it is known that the head of each advance steel pipe is also located above the roof of the next excavation area, and the bottom of each advance hole is located above the roof of the next excavation area.) In the solid rock above the slab, the first end of the advanced steel pipe is supported above the top slab of the next excavation area, forming the first support point of the advanced steel pipe), anchor net, and multiple anchor rods. The end of each advanced steel pipe is exposed in the advanced hole (i.e. exposed at the face section). The anchor net is laid at the bottom of the circumference of the ends of multiple advanced steel pipes, and the anchor rods pass vertically through the anchor net and are anchored in the solid rock above the top slab, thus pressing the ends of multiple advanced steel pipes together through the anchor net and anchor rods, forming the second support point of the advanced steel pipe.

[0008] A construction method for preventing leakage at the face of fractured coal and rock masses includes the following steps: 1) Drilling a row of advance holes evenly distributed along the width of the roadway below the roof of the face section to be excavated, facing upwards towards the roof of the next excavation area, with the bottom end of each advance hole located in the solid rock above the roof of the next excavation area; 2) Preparing multiple advance steel pipes, each matching the number and diameter of the advance holes, and inserting their heads into the bottom of the advance holes (from this, we know that the head of each advance steel pipe is also located in the next excavation area). Above the top plate, so that the first end of the advanced steel pipe is supported above the top plate of the next excavation area, forming the first support point of the advanced steel pipe), and the end of each advanced steel pipe is exposed outside the advanced hole; 3) The bottom of the circumferential surface of the end of multiple advanced steel pipes is supported by the anchor net and multiple anchor rods are used to press the end of multiple advanced steel pipes into the anchor net, thus forming the second support point of the advanced steel pipe; 4) Excavate the preparation excavation area, and after the excavation is completed, a goaf area is formed; 5) Permanent top support is provided for the goaf area, and side support is provided.

[0009] Principle Analysis: The unsupported roof area after excavation in a coal mine roadway is called the "empty roof area." Practice shows that for fractured coal and rock masses, the empty roof is the root cause of face-burst leakage; the larger the empty roof area, the greater the degree and extent of leakage. Eliminating the empty roof is an effective means of preventing face-burst leakage. Face-burst leakage in fractured coal and rock masses often occurs simultaneously with excavation. Therefore, if there can be no empty roof during excavation, face-burst leakage can be fundamentally prevented. Based on this, this invention uses advanced steel pipes to temporarily support and lift the roof in the excavation area to prevent roof leakage after excavation. The specific process involves drilling a row of advance holes and inserting advance steel pipes into them. The first end of the advance steel pipe is located in the solid rock above the roof of the next excavation area, forming the first support point for the advance steel pipe. The end of the advance steel pipe is supported and pressed by anchor mesh and anchor rods, forming the first support point for the advance steel pipe. The two ends of the advance steel pipe are fixed and tightened to the roof of the area to be excavated through the two support points, thus achieving temporary advance support for the roof of the area to be excavated before excavation. As the tunneling progresses, after excavation, a goaf is formed in the area to be excavated, and the top of the goaf exposes the advance steel pipe. Due to the presence of the advance steel pipe, the upper broken coal and rock mass of the goaf is tightly supported by the advance steel pipe, forming temporary support for the broken coal and rock mass, effectively preventing the broken coal and rock mass from leaking out at the head after excavation. After the tunneling is completed, permanent support is then provided for the top of the goaf, and side support is also provided to form the permanent cross-section of the roadway.

[0010] The beneficial effects of this invention are as follows: (1) This method breaks through traditional thinking. By laying advanced steel pipes before excavation, it forms effective temporary support for the upper broken coal and rock mass after excavation. The two-point support advanced steel pipes tighten the roof, eliminating the empty roof after excavation and effectively preventing head leakage. Its concept of eliminating the empty roof and preventing leakage through advanced support breaks through the constraints of commonly used prevention thinking and innovates a new concept for preventing head leakage.

[0011] (2) The method of eliminating voids by supporting the top with steel pipes in advance overcomes the disadvantages of the two commonly used construction control methods, which have many procedures, long time, high cost, small cycle, low efficiency, and difficulty in eliminating voids and local leakage. It innovates a new method for preventing leakage at the head of broken coal and rock mass, and achieves simple operation, convenient process, short time, low cost, large cycle, and high efficiency. It has important application and promotion value.

[0012] (3) It not only formed the advanced steel pipe support method to eliminate the void roof and control the face leakage, which solved the practical problem, but also put forward the view that the void roof is the root cause of the face leakage and that eliminating the void roof is an important means to prevent the face leakage. It innovatively used the concept of eliminating the void roof through advanced support to prevent leakage and implemented the two-point support advanced steel pipe to tighten the roof plate. The advanced steel pipe support method for preventing the face leakage broke through the constraints of commonly used prevention concepts and methods and has important theoretical and practical significance for the control of broken coal and rock masses. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of the front section in this invention (the section line represents solid rock).

[0014] Figure 2 This is a cross-sectional view of the frontal section in this invention (the section line represents solid rock).

[0015] In the diagram: 1—heading section, 2—prepared excavation area, 3—next excavation area, 4—roof, 5—advanced steel pipe, 6—anchor mesh, 7—anchor bolt. Detailed Implementation

[0016] like Figure 1 and Figure 2 As shown, a structure for preventing leakage at the face of fractured coal and rock masses includes a row of advance holes evenly distributed along the width of the roadway, drilled from the face section 1 of the prepared excavation zone 2 below the roof 4 towards the roof 4 of the next excavation zone 3 (the area above the roof 4 is solid rock mass), and advance steel pipes 5 adapted to the advance holes, with their heads inserted into the bottom of the advance holes. (From this, it is known that the head of each advance steel pipe 5 is also located above the roof 4 of the next excavation zone 3, and the bottom of each advance hole is located at the bottom of the next excavation zone 3.) In the solid rock above the top plate 4 of Zone 3, the first end of the advanced steel pipe 5 is supported above the top plate 4 of the next excavation zone 3, forming the first support point of the advanced steel pipe 5), anchor net 6, and multiple anchor rods 7. The end of each advanced steel pipe 5 is exposed outside the advanced hole. After the anchor net 6 is laid at the bottom of the circumference of the ends of multiple advanced steel pipes 5, the anchor rods 7 pass vertically through the anchor net 6 and are anchored in the solid rock above the top plate 4, thereby pressing the ends of multiple advanced steel pipes 5 together through the anchor net 6 and anchor rods 7, forming the second support point of the advanced steel pipe 5. In specific implementation, the angle between the axial direction of the advance hole and the roof plane is 1° to 3°. This ensures that when temporary support is provided for the next excavation zone 3, the height of the end and beginning of the advance steel pipe 5 is basically consistent with the height of the end and beginning of the temporary support established in the previous excavation zone relative to the roof plane 4. This guarantees that the roadway is excavated according to the designed slope and avoids the situation where the advance hole is arranged parallel to the roof plane 4 (when the advance hole is arranged parallel to the roof plane 4, although the end of the advance steel pipe is also below the roof plane 4 and the beginning is also above the roof plane 4, the roof plane 4 of the roadway has gradually deviated from the planned plane), causing the roof plane 4 of the entire excavation roadway to tilt downwards, which would affect the excavation work of the entire roadway. In this specific implementation, the hole spacing between two adjacent advance holes is 200 to 400 mm.

[0017] A construction method for preventing face leakage in fractured coal and rock masses includes the following steps: 1) Drilling a row of advance holes evenly distributed along the width of the roadway below the top plate 4 of the face section 1 of the prepared excavation area 2 and above the top plate 4 of the next excavation area 3, with the bottom end of each advance hole located in the solid rock above the top plate 4 of the next excavation area 3; 2) Preparing multiple advance steel pipes 5, each matching the number and diameter of the advance holes, and inserting their heads into the bottom of the advance holes (from this, it can be inferred that the head of each advance steel pipe 5 is also located in the top of the next excavation area 3). Above the plate 4, so that the first end of the advanced steel pipe 5 is supported above the top plate 4 of the next excavation area 3, forming the first support point of the advanced steel pipe 5), and the end of each advanced steel pipe 5 is exposed outside the advanced hole; 3) The bottom of the circumferential surface of the end of multiple advanced steel pipes 5 is supported by the anchor net 6 and the end of multiple advanced steel pipes 5 is pressed into the anchor net 6 by the anchor rod 7, thus forming the second support point of the advanced steel pipe 5; 4) Excavation preparation area 2 is excavated, and the goaf is formed after the excavation is completed; 5) The top permanent support of the goaf is carried out and the side support is carried out.

[0018] In specific implementation, when the section of the fractured coal and rock mass is relatively long, step 6 is also included: repeating steps 1) to 5) until the section to be excavated passes through the fractured coal and rock mass area. The angle between the axial direction of the advance hole and the roof plane is 1° to 3°. This ensures that when temporary support is provided for the next excavation zone 3, the height of the end and beginning of the advance steel pipe 5 is basically consistent with the height of the end and beginning of the temporary support established in the previous excavation zone relative to the roof plane 4. This ensures that the roadway is excavated according to the designed slope and avoids the roof plane 4 from tilting downwards when the advance hole is arranged parallel to the roof plane 4, which would affect the excavation work of the entire roadway. The depth of the advance hole is 500mm longer than 2 to 3 cycles of advance footage, and the distance between two adjacent advance holes is 200 to 400mm. The diameter of the advance hole is 43mm, and the outer diameter of the advance steel pipe 5 is 42.3mm. The length of the end of the advance steel pipe 5 exposed in the advance hole is 500mm.

[0019] Principle Analysis: The unsupported area of ​​the roof 4 after excavation in a coal mine roadway is called the empty roof area. Practice shows that for fractured coal and rock masses, empty roofs are the root cause of face-rising leaks; the larger the empty roof area, the greater the degree and extent of the leak. Eliminating empty roofs is an effective means of preventing face-rising leaks. Face-rising leaks in fractured coal and rock masses often occur simultaneously with excavation. Therefore, if there can be no empty roof during excavation, face-rising leaks can be fundamentally prevented. Based on this, this invention uses advanced steel pipes 5 to temporarily support and lift the roof 4 in the excavation area to prevent leaks in the roof 4 after excavation. The specific process involves drilling a row of advance holes and inserting advance steel pipes 5 into them. The first end of the advance steel pipe 5 is positioned in the solid rock above the roof 4 of the next excavation zone 3, forming the first support point for the advance steel pipe 5. Anchor mesh 6 and anchor rods 7 support and press the end of the advance steel pipe 5, forming the first support point for the advance steel pipe 5. Both ends of the advance steel pipe 5 are fixed and tightened to the roof 4 of the area to be excavated 2 through the two support points, thus providing temporary advance support for the roof 4 of the area to be excavated 2 before excavation. As the excavation progresses, after excavation, the area to be excavated 2 forms a goaf, with the advance steel pipe 5 exposed at the top. Due to the presence of the advance steel pipe 5, the upper broken coal and rock mass of the goaf is tightly supported by the advance steel pipe 5, forming temporary support for the broken coal and rock mass, effectively preventing leakage of the broken coal and rock mass at the head after excavation. After the excavation is completed, permanent support is provided for the top of the goaf, and side support is also provided to form the permanent cross-section of the roadway.

[0020] Tongfa Dongzhouyao Coal Mine is a 10 million-ton mine under Jineng Holding Coal Industry Group. Its geological conditions are extremely complex, with frequent occurrences of faults, collapse columns, igneous intrusions, and fractured zones. For a period, face-end leakage was a recurring problem. The following is a specific implementation example using the 2103 roadway of the 4# layer: Roadway 2103 is a fully mechanized roadway with a rectangular cross-section, 5.3m wide and 3.5m high, excavated along the coal seam bottom using mechanized excavation. The top coal thickness is approximately 3.5m, and the permanent support consists of anchor mesh 6 (steel mesh) and anchor bolts 7 with steel cable anchors. When excavation reached a section between mileage 594m and 685m, the top coal was fractured and difficult to retain due to the influence of faults and fractured zones. Therefore, the following steps were adopted for construction (e.g....). Figure 1 and Figure 21) Drill a row of advance holes (43mm in diameter, 2.5m deep, 3° angle between the axial direction of the advance hole and the roof plane, and 300mm between adjacent advance holes) evenly distributed along the width of the tunnel at the position below the roof 4 of the facing section 1 of the prepared excavation area 2 and above the roof 4 of the next excavation area 3. The bottom end of each advance hole is located in the solid rock above the roof 4 of the next excavation area 3; 2) Prepare multiple advance steel pipes 5 (42.3mm outer diameter, 3m long) that match the number and diameter of the advance holes. Insert the first end of each advance steel pipe into the bottom of the advance hole, so that the first end of the advance steel pipe 5 is supported above the roof 4 of the next excavation area 3, forming an advance steel pipe. 5) The first support point, and the end of each advanced steel pipe 5 is exposed in the advanced hole with an exposed length of 500mm; 3) The bottom of the circumferential surface of the end of multiple advanced steel pipes 5 is supported by the anchor net 6 and anchored to the solid rock above the top plate 4 by the anchor rod 7 passing through the anchor net 6, thereby pressing the ends of multiple advanced steel pipes 5 into the anchor net 6, forming the second support point of the advanced steel pipe 5; 4) Excavate the preparation excavation area 2, excavate one cycle advance of 1m, and after the cycle excavation, the advanced steel pipe 5 is exposed to support the upper broken coal and rock body; 5) After excavating two cycles advance, it is permanently supported and the side support is carried out; 6) Before the next excavation area 3 is excavated, repeat steps 1) to 5) until the part to be excavated passes through the broken coal and rock body area.

Claims

1. A structure for preventing leakage at the face of fractured coal and rock masses, characterized in that, This includes a row of advance holes evenly distributed along the width of the tunnel, drilled at the face section (1) of the pre-excavation area (2) below the roof (4) and above the roof (4) of the next excavation area (3), as well as advance steel pipes (5), anchor mesh (6), and multiple anchor rods (7) that are adapted to the advance holes and whose heads are inserted into the bottom of the advance holes. The bottom end of each advance hole is located in the solid rock above the roof (4) of the next excavation area (3), and the head of each advance steel pipe (5) is located above the roof (4) of the next excavation area (3). This allows the first end of the advanced steel pipe (5) to be supported above the top plate (4) of the next excavation area (3), forming the first support point of the advanced steel pipe (5). The end of each advanced steel pipe (5) is exposed outside the advanced hole. The anchor mesh (6) is laid on the bottom of the circumferential surface of the ends of multiple advanced steel pipes (5). The anchor rod (7) passes vertically through the anchor mesh (6) and is vertically anchored in the solid rock above the top plate (4), thereby pressing the ends of multiple advanced steel pipes (5) together through the anchor mesh (6) and the anchor rod (7), forming the second support point of the advanced steel pipe (5).

2. The structure for preventing leakage at the face of fractured coal and rock mass according to claim 1, characterized in that, The angle between the axial direction of the advance hole and the top plate plane is 1° to 3°.

3. The structure for preventing leakage at the face of fractured coal and rock mass according to claim 2, characterized in that, The spacing between two adjacent lead holes is 200-400 mm.

4. A construction method for preventing leakage at the face of fractured coal and rock masses, characterized in that, The steps include: 1) Drilling a row of advance holes evenly distributed along the width of the tunnel below the top plate (4) of the face section (1) of the prepared excavation area (2) and above the top plate (4) of the next excavation area (3), with the bottom end of each advance hole located in the solid rock above the top plate (4) of the next excavation area (3); 2) Preparing multiple advance steel pipes (5) that are respectively matched with the number and diameter of the advance holes and inserting their heads into the bottom of the advance holes, with the bottom end of each advance hole located in the solid rock above the top plate (4) of the next excavation area (3), and the head end of each advance steel pipe (5) located in the solid rock above the top plate (4) of the next excavation area (3). Above the top plate (4), so that the first end of the advanced steel pipe (5) is supported above the top plate (4) of the next excavation area (3), forming the first support point of the advanced steel pipe (5), and the end of each advanced steel pipe (5) is exposed in the advanced hole; 3) The bottom of the circumferential surface of the end of multiple advanced steel pipes (5) is supported by the anchor net (6) and the end of multiple advanced steel pipes (5) is pressed into the anchor net (6) by the anchor rod (7), thus forming the second support point of the advanced steel pipe (5); 4) Excavation preparation area (2) is excavated, and the goaf area is formed after the excavation is completed; 5) The top permanent support of the goaf area is carried out, and the side support is carried out.

5. The construction method for preventing leakage at the face of fractured coal and rock mass according to claim 4, characterized in that, It also includes step 6): repeat steps 1) to 5) until the section that needs to be excavated passes through the fractured coal and rock mass area.

6. The construction method for preventing leakage at the face of fractured coal and rock mass according to claim 5, characterized in that, The angle between the axial direction of the advance hole and the top plate plane is 1° to 3°.

7. A construction method for preventing leakage at the face of fractured coal and rock masses according to claim 6, characterized in that, The spacing between two adjacent lead holes is 200-400 mm.

8. The construction method for preventing leakage at the face of fractured coal and rock mass according to claim 7, characterized in that, The diameter of the advance hole is 43mm, the outer diameter of the advance steel pipe (5) is 42.3mm, and the length of the end of the advance steel pipe (5) exposed in the advance hole is 500mm.

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