A method for measuring the height of a fissure zone of a water-rich roof of a coal mine

Abstract

The present application relates to a kind of water-rich roof mining overburden rock fracture zone height measurement method, belong to overburden rock fracture zone height measurement field.Based on the traditional upward hole water injection side leakage method, the measuring process and monitoring equipment are improved.The main steps include: according to the width of coal pillar, coal seam thickness and the range of fracture zone height determined by experience, design drilling angle and depth, and drill into the drilling in the recovery roadway beside goaf.Valve pipe is placed into the drilling and fixed to anchor cable using hemp rope and iron chain, cement slurry is injected into the fracture between valve and drilling wall, ensure that slurry filling is complete and wait for solidification.Continue to drill to the designed depth, send capsule and metal mesh to fracture zone through drill rod, and expand the metal mesh to be fixed on the hole wall by injecting water into the capsule, from top to bottom installation avoids hole collapse.Using improved equipment to carry out sectional water injection test, observe and record water injection flow change.The method improves the safety and accuracy of measurement in water-rich environment, has strong practicability and innovation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of overburden fracture zone height measurement, and particularly relates to a method for measuring the height of the overburden fracture zone of the coal mine roof under water-rich conditions by installing valves and metal nets and improving the monitoring equipment. BACKGROUND

[0002] During the process of coal seam mining, measuring the height of the overburden fracture zone is crucial for ensuring mining safety and improving efficiency. At present, various mature measurement methods have been developed at home and abroad, including drilling flushing fluid observation method, drilling television observation method, geophysical exploration method, and underground upward hole water injection side leakage method. However, these traditional methods are prone to large errors under certain conditions (such as the presence of an overlying water-bearing layer), and even may cause damage to the measurement equipment or induce water inrush accidents at the mining face due to the potential energy of water flow.

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

[0004] Therefore, it is necessary to develop a fracture zone height measurement method suitable for water-rich conditions to reduce measurement errors and improve the stability and reliability of the measurement. The present application aims to propose a measurement method for the water-bearing layer of the roof based on the traditional underground upward hole water injection side leakage method. The core is to install a valve at the drilling hole, use the valve to send the test equipment into the drilling hole for measurement, and at the same time block the water and silt of the water-bearing layer to protect the construction personnel and the mining face; install a metal net in the drilling hole from top to bottom to effectively prevent the drilling hole from collapsing and maintain the drilling passage to provide a stable environment for measurement; improve the measurement equipment to drain the roof water to avoid the danger caused by the high-speed rush of the accumulated water in the drilling hole. SUMMARY

[0005] The present application 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 water-bearing layers in the overlying rock. Therefore, a method of blocking water by valve, protecting by metal net, and improving measurement equipment is designed to ensure accurate fracture zone measurement in water-rich environment.

[0006] This invention proposes a method for measuring the height of overburden fracture zones in water-rich coal mine roofs. This technology allows traditional overburden fracture height observation methods to be applied to overburden fracture height measurement under water-rich conditions. By installing a valve at the borehole opening, installing a metal mesh inside the borehole, and improving monitoring equipment, this method effectively protects construction personnel and equipment, reduces interference with mining operations caused by water inrush from the borehole, and ensures accurate and stable measurement.

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

[0008] (1) 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. 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 to the roof of the mining tunnel next to the goaf according to the designed angle and diameter. The length is generally 5m to 15m, and the hole is drilled to the side of the working face (i.e., the opposite direction of the goaf).

[0009] A contrasting hole is drilled in the top plate at a designed angle.

[0010] (2) Wrap a hemp rope around the bottom hole of the valve pipe and place the valve pipe into the drilled hole. Use an iron chain to fix it to the anchor cable on the nearby roof. 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 maintain 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 toward the top plate at the designed angle until the designed depth is reached. In the case of water-rich top plate, water inflow from the aquifer can easily cause the borehole to collapse. To prevent this, 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 from bottom to top in sections, and in the process of injecting water in sections, the pressure of the capsule for injecting water and measuring leakage is higher than the natural pressure of the water column at the height by 3-6 MPa, and the flow changes of each section of water injection in the borehole are observed and recorded.

[0014] Compared with the conventional roof water injection side leakage method, the present application has the following advantages:

[0015] First, it is suitable for the condition of water-rich roof, and in the case of water outflow from the roof, the conventional method of grouting will cause the grout to be washed away by the roof water, and the present application solves the problem of grout loss under the condition of water-rich roof of coal mine by the method of high-pressure grouting from bottom to top when installing the valve, and has high practicability.

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

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

[0018] Figure 1 Overall schematic diagram of coal water-rich roof mining overburden fractured zone height measurement method

[0019] Figure 2 Valve installation schematic diagram

[0020] Figure 3 Metal mesh installation schematic diagram

[0021] Figure 4 Inside-hole capsule-type hole sealer modification schematic diagram

[0022] Figure 5 Coal water-rich roof mining overburden fractured zone height measurement flowchart

[0023] In the drawings, the components are marked as follows: 1. coal body; 2. roadway; 3. drilling machine; 4. valve switch; 5. cement slurry; 6. valve sleeve; 7. drill pipe; 8. metal mesh; 9. working face goaf; 10. rock fractured zone; 11. inside-hole capsule-type hole 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 mining overburden fissure height of coal mine in the condition of more aquifer and easy gushing, the present application provides a kind of coal mine water-rich roof mining overburden fissure zone height measuring method, the present application is further described below in conjunction with the drawings, including the following structure, principle and specific implementation steps:

[0025] As shown in the drawings, the overall structure of the coal mine water-rich roof mining overburden fissure zone height measuring method includes coal body 1, a part of the coal seam reserved during the coal mining process to ensure the safety and stability of the roadway. Mining roadway 2, a channel for transporting equipment and personnel. Drilling machine 3, the power source of the telescopic drill rod. Valve switch 4, control the switch of the drilling channel, open the drill rod and monitoring equipment, close the roof water into the working face. Cement slurry 5, after solidification, the valve sleeve is fixed and the drilling wall is consolidated. Valve sleeve 6, consolidate the channel. Drill rod 7, used for drilling and transportation and placement of monitoring equipment. Metal mesh 8, placed in the drilling wall, prevent drilling collapse and drilling wall deformation. In-hole capsule-type hole sealer 11, after inflation before water injection to measure fissure height, it can block the drilling to isolate the influence of external water on measurement, while avoiding water loss during the water filling process of the measurement section. Hole blocking operation table 12, the operation platform for controlling the expansion and contraction of the capsule hole sealer. Water injection operation table 13, control the water injection operation platform to the overburden fissure zone, and can record the water injection amount. Hemp rope 14, wound around the sleeve port and fixed on the nearby anchor cable by iron chain to fix the valve. Water cement slurry hole 15, water cement slurry is injected into the gap between the sleeve and the hole wall through the water cement slurry hole. Capsule 16, water is injected into it to make the metal mesh expand to be fixed on the drilling wall. Drainage steel pipe 17, installed in the capsule and the capsule hole sealer, discharges the roof water from the capsule downward.

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

[0027] First, according to the coal pillar width design to the goaf roof drilling angle, according to the seam thickness and experience method to determine the fracture zone height range, combined with the drilling angle to determine the different angle drilling depth, then according to the drilling design requirements, in the goaf 9 next to the recovery roadway 2 using drilling machine 3 according to the design angle and diameter to the roof installation valve pipe length drilling, and to the working face side (ie goaf opposite direction) roof with design angle drilling. In the valve pipe bottom hole orifice winding rope 14 and the valve pipe 6 into the hole, with iron chain fixed in the nearby roof anchor cable, then through the reserved cement slurry injection hole 15 between the valve and the drilling wall gap injection cement slurry 5, when the cement slurry between the valve and the drilling wall, make the slurry from bottom to top fill the gap between the valve and the drilling wall, when the cement slurry overflow from the valve pipe, stop grouting, and let the cement slurry solidification 24 hours. Continue to drill according to the design angle to the roof, until the design depth, then use the drill pipe 7 to capsule 16 and metal mesh 8 to the drilling fracture zone, and to the capsule injection water to make the metal mesh 8 expansion fixed to the drilling wall, metal mesh from top to bottom installation, avoid the hole collapse. Close to the hole capsule iron pipe wall installation of a drainage steel pipe 17, drainage steel pipe 17 upper end straight through the hole packer top, the lower end to the hole packer bottom side bending, sparse in the test stage of the roof water. Measure the capsule packer 11 in the contraction state of the diameter, to ensure that the capsule packer to move normally, then to the modified capsule packer 11 injection water, observe whether it is normal expansion and no leakage phenomenon, then test the remaining monitoring equipment. After connecting the monitoring equipment and the corresponding pipeline, the modified capsule packer 11 is sent into the hole fracture zone, and the hole closing operation platform 12 is controlled to inject water into the capsule packer 11. The capsule packer 11 is inflated under the action of high pressure water to seal the hole, and then the water injection operation platform 13 is controlled to inject water into the sealing section to monitor the water flow of the sealing section. After the test, the capsule is depressurized, and the packer is moved 1 m, and the operation of the previous step is continued until the hole bottom is reached. By injecting water from bottom to top, the water flow of each section in the drilling is observed and recorded.

Claims

1. A method for measuring the height of the overburden fracture zone in a water-rich coal mine roof. Considering that the roof contains aquifers when measuring the height of the overburden fracture zone under water-rich conditions, drilling directly upward will cause water inrush into the borehole, thereby affecting subsequent valve installation and grouting work, and causing internal collapse of the borehole, making it impossible to place 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 toward the goaf roof based on the coal pillar width, determine the height range of the fracture zone based on the coal seam thickness and empirical methods, and determine the drilling depth at different angles based on the drilling angle; (b) According to the drilling design requirements, drill a hole toward the goaf roof in the mining roadway next to the goaf, and drill a comparison hole toward the roof on the working face side at the designed angle. The working face side is the opposite direction of the goaf; (c) First, use a drilling rig to drill a hole in the roof at the designed angle and diameter 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. Secure it to the anchor cable on the roof with an iron chain. When grouting the valve, to prevent the slurry from being washed away by water from the roof, inject cement slurry into the gap between the valve and the borehole wall through the reserved grouting hole. Fill the gap between the valve and the borehole wall with slurry from bottom to top. Stop grouting when the cement slurry overflows from the valve pipe and allow the cement slurry to solidify for 24 hours. (d) Continue drilling towards the roof until the designed depth is reached. To prevent the borehole from collapsing due to water inflow from the aquifer, install a metal mesh from top to bottom in the borehole. Use a drill rod to transport the metal mesh to the borehole fracture zone, and inject water into the capsule to expand the metal mesh and fix it to the borehole wall. (e) When injecting water into the plugged borehole to measure the fracture height, roof water will accumulate on the upper part. To prevent the accumulated roof water from falling from a high place with huge potential energy when the sealer is depressurized and posing a danger to the on-site test, the test equipment is modified to drain the roof water accumulated during the test phase; (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. A method for measuring the height of the overburden fracture zone of the water-rich roof of a coal mine according to claim 1, wherein a drainage pipe is added to the improved upstream hole water injection test equipment to drain the roof water accumulated during the test phase, thereby avoiding the danger caused by the high-speed rushing of water accumulated in the borehole. The diameter of the improved drainage pipe ranges from 4cm to 6cm.

3. 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 length of the valve sleeve is related to the thickness of the top coal and is to be fixed into the roof rock layer, and is generally 5m to 15m long.

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 into the goaf is related to the width of the coal pillar and the angle range is 60° to 80°.

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

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

Images