Method for measuring height of coal mine water-rich roof mining overlying strata fissure zone

Abstract

The invention relates to a method for measuring the height of a water-rich roof mining overlying strata fissure zone, and belongs to the field of overlying strata fissure zone height measurement. Based on a traditional upward hole water injection side leakage method, the measuring process and monitoring equipment are improved. The method mainly comprises the steps that the height range of a fissure zone is judged according to the width of a coal pillar, the thickness of a coal seam and experience, the drilling angle and depth are designed, and a hole is drilled in a mining roadway beside a goaf; the valve pipe is placed into the drill hole and fixed to the anchor cable through a hemp rope and an iron chain, cement paste is injected into a crack between the valve and the wall of the drill hole, and it is ensured that the paste is completely filled and waits for solidification. Continuously punching to the designed depth, conveying the capsule and the metal net to the fissure zone through a drill rod, injecting water into the capsule to enable the metal net to expand and be fixed on the hole wall, and mounting from top to bottom to avoid hole collapse. The improved equipment is used for performing section-by-section water injection test, and water injection flow change is observed and recorded. According to the method, the safety and accuracy of measurement in the water-rich environment are improved, and the method has relatively high practicability and innovativeness.

Description

Technical Field

[0001] The invention belongs to the field of overburden fracture zone height measurement, and specifically relates to a method for measuring the overburden fracture zone height of a coal mine roof by installing valves and metal meshes and modifying monitoring equipment under water-rich conditions. Background Art

[0002] In the process of coal mining, measuring the height of the overburden fracture zone is crucial to ensure mining safety and improve efficiency. At present, a variety of mature measurement methods have been developed at home and abroad, including borehole flushing fluid observation method, borehole television observation method, geophysical detection method and underground upwelling water injection side leakage method. However, these traditional methods are prone to large errors under certain conditions (such as when there is an aquifer in the overburden stratum), and may even cause damage to the measuring equipment or cause water intrusion accidents at the mining face due to the potential energy of the water flow.

[0003] Each measurement method has its own advantages and disadvantages. Among them, the underground upturned hole water injection side leakage method is favored because of its simple operation and small amount of engineering. In recent years, the rapid development of underground drilling rig technology has greatly improved construction efficiency and can correct errors in time. In addition, the data obtained by this method is relatively reliable, and the equipment cost and operating cost are low. However, under water-rich conditions, this method cannot accurately measure the height of the overburden fracture zone, and may cause water intrusion into the working face due to water gushing from the aquifer.

[0004] Therefore, it is necessary to develop a fracture zone height measurement method suitable for water-rich conditions to reduce measurement errors and improve measurement stability and reliability. The present invention aims to propose a measurement method for the roof aquifer based on the traditional underground upturned hole water injection and side leakage method. The core is to install a valve at the borehole mouth, use the valve to send the test equipment into the borehole for measurement, and at the same time block the water and sediment in the aquifer, thereby protecting the construction personnel and the mining face; install a metal mesh from top to bottom in the borehole to effectively prevent the collapse of the borehole, and maintain the borehole channel to provide a stable environment for measurement; improve the measuring equipment to drain the roof water to avoid the danger caused by the high-speed rushing of the water accumulated in the borehole. Summary of the invention

[0005] The present invention aims to solve the problem that the traditional overburden fracture zone height measurement method cannot be effectively applied under water-rich conditions, especially for coal mines with overburden aquifers. To this end, a method is designed to ensure accurate fracture zone measurement in water-rich environments by blocking water with valves, protecting with metal meshes, and improving measuring equipment.

[0006] The present invention proposes a method for measuring the height of overburden fracture zone in water-rich roof mining of coal mines. The technology can realize the application of the traditional overburden fracture height observation method to the overburden fracture zone height measurement under water-rich conditions. By installing valves at the borehole mouth, installing metal mesh in the borehole and improving monitoring equipment, construction personnel and equipment can be effectively protected, the interference of water inrush from the borehole on the mining operation can be reduced, and the accuracy and stability of the measurement process can be ensured.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] (1) First, the drilling angle is designed according to the width of the coal pillar. The height range of the fracture zone is determined according to the thickness of the coal seam and empirical methods. The drilling depth at different angles is determined in combination with the drilling angle. The general drilling angle range is 60° to 80°. Then, according to the drilling design requirements, a drilling rig is used to drill a hole of the length of the valve pipe installation on the roof of the mining tunnel next to the goaf according to the designed angle and diameter. The general length is 5m to 15m, and the hole is drilled to the side of the working face (i.e., the opposite direction of the goaf).

[0009] The top plate is drilled with a contrast hole at a designed angle.

[0010] (2) Wrap hemp rope around the hole at the bottom of the valve pipe and put the valve pipe into the drilled hole, and fix it to the anchor cable of the nearby roof with an iron chain. When grouting the valve, in order to prevent the slurry from being washed away by the roof water, inject cement slurry into the gap between the valve and the drilled hole wall through the reserved grouting hole, so that the slurry fills the gap between the valve and the drilled hole wall from bottom to top, and keep the grouting pressure at 2MPa~4MPa. When the cement slurry overflows from the valve pipe, stop grouting and let the cement slurry solidify for 24 hours.

[0011] (3) Continue drilling towards the top plate at the designed angle until the designed depth is reached. When the top plate is water-rich, water inflow from the aquifer can easily lead to borehole collapse. To prevent the collapse of the borehole, a metal mesh will be installed from top to bottom in the borehole. The capsule and the metal mesh will be transported to the borehole fracture zone using a drill rod, and water will be injected into the capsule to expand the metal mesh and fix it to the borehole wall.

[0012] (4) When the plugged borehole is injected with water to measure the height of the crack, roof water will accumulate on the upper part. In order to prevent the accumulated roof water from falling from a high place with huge potential energy when the sealer is depressurized and causing danger to the on-site test, a drainage steel pipe will be installed close to the inner wall of the iron pipe of the capsule sealer in the hole. The diameter of the drainage steel pipe ranges from 4cm to 6cm. The upper end of the drainage pipe goes straight to the top of the sealer, and the lower end is bent toward the bottom side of the sealer to drain the roof water accumulated during the test stage.

[0013] (5) The improved test equipment is pushed into the borehole through the drill pipe, and water is injected section by section from bottom to top. During the injection process, the pressure of the water loss measured in the middle of the capsule should be 3MPa to 6MPa higher than the natural pressure of the water column at that height. The flow rate changes of each section of the water injection in the borehole are observed and recorded.

[0014] Compared with the traditional underground upward hole water injection side leakage method, the present invention has the following advantages:

[0015] First, it is adaptable to the condition of water-rich roof. When water comes out of the roof, grouting by conventional methods will cause the slurry to be washed away by the roof water. However, the present invention solves the problem of slurry loss when the roof of the coal mine is rich in water by using a bottom-up high-pressure grouting method when installing the valve, and has high practicality.

[0016] Second, improve measurement stability. Installing a metal mesh from top to bottom through the drill rod can effectively prevent hole collapse and excessive deformation of the hole wall, maintain the drilling channel, and ensure normal movement of the equipment during the monitoring process.

[0017] Third, to protect construction equipment, through the improved drainage pipe design, the roof water accumulated in the borehole due to the expansion of the capsule can be effectively drained to avoid equipment damage and safety accidents caused by excessive potential energy of the water flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Overall schematic diagram of the height measurement method of overburden fracture zone caused by mining in water-rich roof of coal mine

[0019] Figure 2 Valve installation diagram

[0020] Figure 3 Metal mesh installation diagram

[0021] Figure 4 Schematic diagram of the modification of the capsule-type hole sealer in the hole

[0022] Figure 5 Flow chart of height measurement of overburden fracture zone caused by mining of water-rich roof in coal mine

[0023] The components in the attached figure are marked as: 1. Coal body; 2. Tunnel; 3. Drilling rig; 4. Valve switch; 5. Cement slurry; 6. Valve casing; 7. Drill rod; 8. Metal mesh; 9. Goaf of working face; 10. Rock fracture zone; 11. In-hole capsule sealer; 12. Hole plugging operation table; 13. Water injection operation table; 14. Hemp rope; 15. Cement slurry injection hole; 16. Capsule; 17. Drainage steel pipe. DETAILED DESCRIPTION

[0024] In order to measure the height of overburden fractures in coal mines with abundant aquifers and prone to gushing, the present invention provides a method for measuring the height of overburden fracture zones in water-rich roof mining in coal mines. The present invention is further explained below in conjunction with the accompanying drawings, including the following structure, principle and specific implementation steps:.

[0025] As shown in the attached figure, the overall structure of a method for measuring the height of the overburden fracture zone of the water-rich roof of a coal mine includes a coal body 1, which is a part of the unmined coal seam retained during coal mining to ensure the safety and stability of the tunnel. A mining tunnel 2, a passage for transporting equipment and personnel. A drilling rig 3, a power source for the extension and retraction of the drill rod. A valve switch 4, which controls the switch of the drilling channel. When it is opened, it can pass through the drill rod and monitoring equipment, and when it is closed, it can block the water from the roof from entering the working face. Cement slurry 5, which fixes the valve sleeve and consolidates the borehole wall after solidification. Valve sleeve 6, consolidates the channel. Drill rod 7, which is used for the transportation and placement of drilling and monitoring equipment. Metal mesh 8, which is placed on the borehole wall to prevent the collapse of the borehole and excessive deformation of the borehole wall. An in-hole capsule sealer 11, which can seal the borehole after being filled with water and expanded before water injection to measure the fracture height, isolating the influence of external water on the measurement, and at the same time avoiding the loss of water during the water filling process of this measuring section. A plugging operation table 12, an operating platform for controlling the expansion and contraction of the capsule sealer. The water injection operation table 13 is an operation platform for controlling water injection into the overburden fracture zone, and can be used to record the amount of water injected. The hemp rope 14 is wound around the casing mouth and fixed to the nearby anchor cable through an iron chain to fix the valve. The cement slurry injection hole 15 is used to inject cement slurry into the gap between the casing and the hole wall. The capsule 16 is filled with water to expand the metal mesh until it is fixed on the borehole wall. The drainage steel pipe 17 is installed in the capsule and the capsule sealer to drain the top plate water downward from the capsule.

[0026] With the above structure, the specific implementation method and principle are as follows:

[0027] First, the drilling angle is designed to the roof of the goaf according to the width of the coal pillar, the height range of the fracture zone is determined according to the thickness of the coal seam and the empirical method, and the drilling depth at different angles is determined in combination with the drilling angle. Then, according to the drilling design requirements, a drilling machine 3 is used to drill a hole of the length of the valve pipe installation in the roof of the recovery tunnel 2 next to the goaf 9 according to the designed angle and diameter, and a comparative drilling hole is drilled at the designed angle to the roof of the working face side (i.e., the opposite direction of the goaf). Wrap a hemp rope 14 around the bottom hole of the valve pipe and put the valve pipe 6 into the borehole, fix it to the anchor cable of the nearby roof with an iron chain, and then inject cement slurry 5 into the gap between the valve and the borehole wall through the reserved cement slurry injection hole 15. When injecting cement slurry between the valve pipe and the borehole wall, the slurry fills the gap between the valve and the borehole wall from bottom to top. When the cement slurry overflows from the valve pipe, stop grouting and let the cement slurry solidify for 24 hours. Continue to drill holes into the roof at the designed angle until the designed depth is reached. Then use the drill rod 7 to transport the capsule 16 and the metal mesh 8 to the fissure zone of the borehole, and inject water into the capsule to expand the metal mesh 8 and fix it to the borehole wall. The metal mesh is installed from top to bottom to avoid hole collapse. Install a drainage steel pipe 17 close to the inner wall of the iron pipe of the capsule sealer in the hole. The upper end of the drainage steel pipe 17 goes straight through the top of the sealer, and the lower end is bent toward the bottom side of the sealer to drain the roof water accumulated during the test phase. Measure the diameter of the capsule sealer 11 in the contracted state and make sure it is smaller than the diameter of the borehole to ensure that the capsule sealer moves normally. Then inject water into the modified capsule sealer 11 to observe whether it expands normally and there is no water leakage. Then test the remaining monitoring equipment. After connecting the monitoring equipment and the corresponding pipelines, the modified capsule-type sealer 11 is sent into the fissure zone in the hole, and the plugging operation table 12 is controlled to inject water into the capsule-type sealer 11. The capsule sealer 11 expands under the action of high-pressure water to seal the borehole, and then the water injection operation table 13 is controlled to inject water into the plugging section to monitor the water flow in the plugging section. After the test is completed, the capsule is depressurized, and the sealer is moved inward 1m, and the previous operation is continued until it reaches the bottom of the hole. By injecting water section by section from bottom to top, the flow changes of each section of the water injection in the borehole are observed and recorded.

Claims

1. A method for measuring the height of the overburden fracture zone of a water-rich roof in a coal mine. Considering that when measuring the height of the overburden fracture zone of a coal seam under water-rich conditions, there is an aquifer on the roof. If a hole is drilled directly upward, water will burst from the borehole, which will affect the subsequent valve installation and grouting work, and may cause the borehole to collapse, making it impossible to place the test equipment. Therefore, the following steps are performed when measuring the height of the overburden fracture zone under water-rich conditions: (a) Design the drilling angle to the roof of the goaf according to the width of the coal pillar, determine the height range of the fracture zone according to the thickness of the coal seam and empirical methods, and determine the drilling depth at different angles in combination with the drilling angle; (b) According to the drilling design requirements, drill a hole towards the roof of the goaf in the mining tunnel next to the goaf, and drill a comparison hole at the designed angle towards the roof of the working face side (i.e. the opposite direction of the goaf); (c) First, use a drilling rig to drill a hole of the designed angle and diameter into the top plate to the length of the valve pipe. Wrap a hemp rope around the bottom hole of the valve pipe and place the valve pipe into the hole. Use an iron chain to fix it to the anchor cable of the top plate nearby. When grouting the valve, in order to prevent the slurry from being washed away by the water on the top plate, inject cement slurry into the gap between the valve and the borehole wall through the reserved grouting hole, so that the slurry fills the gap between the valve and the borehole wall from bottom to top. When the cement slurry overflows from the valve pipe, stop grouting and let the cement slurry solidify for 24 hours; (d) Continue drilling towards the top plate until the designed depth is reached. To avoid the collapse of the borehole caused by water inflow from the aquifer, install a metal mesh from top to bottom in the borehole, transport the metal mesh to the borehole fracture zone using a drill rod, and inject water into the capsule to expand the metal mesh and fix it to the borehole wall; (e) When the plugged borehole is injected with water to measure the fracture height, roof water will accumulate on the upper part. In order to prevent the accumulated roof water from falling from a high place with huge potential energy when the plugging device is depressurized and causing danger to the on-site test, the test equipment is modified to drain the roof water accumulated during the test stage; (f) The improved test equipment is pushed into the borehole through the drill pipe, and water is injected section by section from bottom to top. The flow rate changes of each section of the borehole are observed and recorded.

2. According to the method for measuring the height of the overburden fracture zone of the water-rich roof of a coal mine as described in claim 1, a drainage pipe is added to the improved upstream hole water injection test equipment to drain the roof water accumulated during the test phase to avoid the water accumulated in the borehole rushing down at high speed and causing danger. The diameter range of the improved drainage pipe is 4cm to 6cm.

3. According to the method for measuring the height of the overburden fracture zone in the water-rich roof of a coal mine as described in claim 1, the length of the valve sleeve is related to the thickness of the top coal and is to be fixed in the roof rock layer, and the general length is 5m to 15m.

4. A method for measuring the height of overburden fracture zones in water-rich roof mining in a coal mine according to claim 1, wherein the angle of drilling holes into the goaf is related to the width of the coal pillar, and the general angle range is 60° to 80°.

5. A method for measuring the height of overburden fracture zone in water-rich roof of a coal mine according to claim 1, wherein when injecting cement slurry between the valve pipe and the borehole wall, the grouting pressure is maintained at 2MPa to 4MPa.

6. A method for measuring the height of overburden fracture zones in water-rich roof mining in a coal mine according to claim 1, wherein the water injection pressure of capsules on both sides of the test device is 1MPa to 3MPa higher than the pressure of the leakage on the middle water injection side.

7. A method for measuring the height of overburden fracture zones in water-rich roof mining in a coal mine according to claim 1, wherein during the step-by-step water injection process, the pressure of the capsule for measuring the leakage volume during the middle water injection is 3MPa to 6MPa higher than the natural pressure of the water column at that height.

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