A method for monitoring the deformation and damage height of overburden rock in a mining area

Abstract

The present invention discloses a method for monitoring the deformation and damage height of the overburden rock in a mining area, including collecting basic data of the working face of the mining area to be tested; obtaining the predicted height of the development of two zones of the ore layer mining; determining the position of the tunnels in the working face of the mining area and the position of the tunnels around the working face, and arranging underground directional monitoring boreholes; performing directional drilling construction, installing fixed distributed optical fibers in the holes and connecting the monitoring system; distributed optical fiber monitoring during the mining process of the working face; obtaining the development height of the two zones of the overburden rock based on data analysis; the present invention adopts a directional drilling method, and also achieves the consistency of the monitoring data collection order and the deformation and damage order of the working face overburden rock in the underground, which can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole layout method commonly used in underground. In addition, the installation of distributed optical fibers in directional drilling adopts the method of dragging back from the drill tail to the hole mouth, which can also effectively prevent the problem of optical fiber breakage caused by lowering the optical fiber from the hole mouth.

Description

Technical Field

[0001] The invention relates to the field of methods for monitoring the deformation and damage height of overburden rock on a mining site roof, and in particular to a method for monitoring the deformation and damage height of overburden rock on a mining site roof. Background Art

[0002] At present, among the methods for obtaining the height of the two-zone development, the distributed optical fiber monitoring method mainly uses the strain and breakpoint monitoring function of the distributed optical fiber. The distributed optical fiber is implanted in the section to be tested by drilling. During the mining process of the working face, the monitoring data of the optical fiber is obtained to analyze the deformation and damage of the roof overburden, and then obtain the height data of the two-zone development. The existing roof overburden monitoring method has two forms of monitoring drilling arrangements. One is to construct vertical holes on the ground corresponding to the working face mining site. The other is to set up a drilling site on both sides of the working face or in the tunnel inside the working face to construct holes obliquely upward toward the roof of the working face. The holes are all straight holes, and monitoring optical fibers are installed in the holes. The drilling construction and optical fiber installation are completed before the working face is mined. During the mining process of the working face, the optical fiber data is monitored in real time, and then the height of the two zones of overburden development is obtained by analysis.

[0003] Overall, the current method of laying monitoring holes on the ground (such as Figure 3 ), the monitoring data is the most accurate, because from the time sequence, the overburden fracture develops gradually from the direct roof of the ore layer upward. The ground drilling data collector is on the ground, and can use the optical fiber monitoring data and breakpoint monitoring function in real time to see the fracture development of the overburden from bottom to top. The monitoring process is consistent with the overburden fracture process. The data obtained by the current underground monitoring drilling method has major problems and cannot accurately indicate the height of the two zones. At present, underground monitoring boreholes are generally opened on both sides of the working face or in the tunnels within the face, and then arranged in the direction of the working roof and the working face cut. The maximum vertical height controlled by the drilling must exceed the maximum height of the predicted development of the two zones.

[0004] like Figure 4 As shown in the figure, since the deformation and fracture of the overburden rock in the mining area is generally advanced, and the advanced area is not in a standard shape, it is easy to cause the height of the two zones judged by monitoring data to be lower than the actual development height. Figure 5As shown in the figure, according to the monitoring data, the optical fiber first had a breakpoint at a vertical height of about 35m. Conventionally, it is judged that the height of the two zones is about 35m, while the actual development of the two zones of the roof overburden is more than 40m. This phenomenon occurs mainly because the monitoring downhole gradually obtains the response data from the bottom of the hole to the hole mouth, and gradually obtains the monitoring parameters from the deep part of the overburden to the shallow part, while the actual overburden deformation and damage gradually develops from the direct top to the deep part. In this way, the order of monitoring data acquisition is opposite to the order of overburden deformation and damage, which is easy to cause misjudgment. If the extension direction of the downhole hole is changed, that is, from the tunnel opening, upward and in the opposite direction of the cut eye, the deformation of the roof overburden gradually develops from the direct top to the top, which will first destroy the position of the monitoring hole mouth, directly destroy the entire monitoring system, and cannot obtain further data.

[0005] Based on the above analysis, there are two main ways to arrange distributed optical fiber monitoring holes in the two zones of the overburden in the mining area: ground and underground. The overall monitoring accuracy of ground holes is relatively high, but a drilling site needs to be arranged on the ground. Some ground is restricted by mountains, rivers, etc., or policy restrictions, and there are no conditions for drilling. In addition, for working conditions with thick overburden loose layers, such as Juye Coalfield in my country, drilling is difficult, risky, and expensive. The commonly used extension method of underground drilling to obtain monitoring results is prone to errors, and changing the extension direction cannot achieve full-process monitoring. Summary of the invention

[0006] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for monitoring the deformation and damage height of the overburden rock in the mining area roof. It is essentially a method for underground monitoring drilling holes. It mainly uses directional drilling technology to arrange drilling holes in the circle or internal tunnels of the underground working face to be tested. The drilling trajectory first goes upward to bypass the maximum position of the predicted development height of the two belts, and then the drilling trajectory goes downward to finally expose the tunnel in the working face. Then, distributed optical fibers are installed throughout the hole, and the optical fiber is connected to the monitoring data acquisition equipment at the borehole mouth to realize the monitoring of the deformation and damage of the roof overburden rock during the whole mining process of the ore layer. The optical fiber in the drilling section in the downward direction of the tail section of the borehole realizes a function similar to ground drilling. The monitoring data acquisition is carried out from the bottom of the hole upward, which is consistent with the direction of deformation and damage of the mining area overburden rock. This method can realize the accurate monitoring of the development height of the two belts using the distributed optical fiber method underground.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for monitoring the deformation and damage height of the overburden rock in a mining area, comprising the following steps:

[0009] Step S1, collecting basic data of the working face of the stope to be tested;

[0010] Step S2, using empirical formulas, formulas recommended by specifications, and numerical analysis methods to preliminarily obtain the predicted height of the development of two zones in the ore layer mining;

[0011] Step S3, determining the position of the tunnels in the working face of the stope and the positions of the tunnels around the working face, and arranging underground directional monitoring drilling holes;

[0012] Step S4: perform directional drilling, install and fix the distributed optical fiber in the hole and connect it to the monitoring system;

[0013] Step S5, distributed optical fiber monitoring during the mining process of the working face;

[0014] Step S6: Obtain the development height of the two zones of overburden according to data analysis.

[0015] Preferably, in step S1, the basic data include mining thickness, mining technology, roof overburden structure, overburden lithology, overburden strength, ore layer burial depth, working face length and width specifications, ore layer inclination, and working face structural development.

[0016] Preferably, in step S2, if there are measured data for the mines near the mining area, the data of the nearby mines are used to predict the development heights of the two zones of the working face of the ore layer to be measured; or a numerical analysis model is constructed according to the working face conditions of the mining area to analyze and calculate the development heights of the two zones of the overburden.

[0017] Preferably, in step S3, if there is no tunnel in the working face of the stope, a position is selected, and a tunnel is constructed along the ore layer from the tunnel openings on both sides of the working face into the working face of the stope, and the length of the tunnel entering the working face is not less than 20m. According to the overall layout of the tunnels in the working face, underground directional monitoring drilling holes are arranged;

[0018] The highest point of the directional drilling needs to be higher than the predicted maximum height of the two zones, and be higher than 5 times the coal seam thickness. The drilling points are in the tunnels on both sides of the working face of the mining area. The overall extension direction of the directional hole is to point to the cutting eye of the working face and the connected tunnel on the opposite side. The trajectory of the directional hole first goes upward, bypassing the maximum position of the predicted height of the two zones, and then the drilling trajectory goes downward, finally exposing the tunnel in the working face.

[0019] Preferably, in step S4, the drilling is constructed according to the designed trajectory, and a borehole casing is installed at the borehole mouth, the casing length is not less than 8m, and after the drilling exposes the tunnel in the surface, an 8m borehole tail casing is also installed at the tail section of the drilling hole, and then the optical fiber is installed into the hole by back-pulling the distributed optical fiber; finally, slurry is used to grout the monitoring borehole, and the distributed optical fiber and the borehole surrounding rock are coupled into one through the slurry, and the borehole mouth optical fiber is connected to the distributed monitoring equipment to form a mining field overburden deformation and damage monitoring system.

[0020] Preferably, in step S4, the method of pulling back the optical fiber is that the optical fiber is first placed in a tunnel in the surface of the bottom of the hole, the optical fiber is connected to the drill bit in the hole, and then the hole is drilled and the drill rod is pulled out, and the optical fiber enters the borehole along with the pulled drill bit. After the drill rod is completely pulled out of the borehole, the entire section of the distributed optical fiber is installed in the monitored directional borehole.

[0021] Preferably, in step S5, distributed optical fiber monitoring is performed during the working face recovery process to obtain relevant data. Data monitoring starts from the working face recovery position 100m away from the tail end of the directional drilling and ends when the working face is recovered to the directional drilling opening point. The monitoring frequency is no less than once a day.

[0022] Preferably, in step S6, the overburden strain data of the entire monitoring drilling trajectory is obtained through data analysis, and the deformation and damage of the overburden and the development height of the roof cracks are further analyzed to obtain the two-zone development height of the measured mining field working face.

[0023] The beneficial effect of the present invention is that: the present invention adopts the directional drilling method, and also realizes the consistency of the monitoring data collection order and the deformation and damage order of the overburden at the working face in the well, which can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole arrangement method commonly used in the well. In addition, the installation of distributed optical fiber in directional drilling adopts the method of pulling back from the drill tail to the hole mouth, which can also effectively prevent the problem of optical fiber breakage caused by lowering the optical fiber from the hole mouth. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A cross-sectional view of the drilling arrangement in step S3 provided in an embodiment of the present invention;

[0026] Figure 2 A plan view of the arrangement of drilling holes in step S3 provided in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of laying monitoring holes on the ground using the existing technology;

[0028] Figure 4 A cross-sectional diagram of the arrangement of downhole monitoring holes in the prior art;

[0029] Figure 5 This is the result of optical fiber monitoring of overburden deformation in a mine using existing technology. DETAILED DESCRIPTION

[0030] 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.

[0031] The present embodiment provides a method for monitoring the deformation and damage height of the overburden rock in a mining area roof, and the specific steps include: ① collecting basic data of the working face of the mining area to be tested → ② using empirical formulas, formulas recommended by specifications, numerical analysis and other methods to preliminarily obtain the predicted height of the development of two zones of mining in the ore layer → ③ determining the position of the tunnels in the working face of the mining area and the position of the tunnels around the working face, and arranging underground directional monitoring drilling holes → ④ conducting directional drilling construction, installing fixed distributed optical fibers in the holes and connecting them to the monitoring system → ⑤ distributed optical fiber monitoring during the mining of the working face → ⑥ obtaining the development height of the two zones of overburden rock based on data analysis.

[0032] ① Collect basic data of the working face of the mining area to be tested, including mining thickness, mining technology, roof overburden structure, overburden lithology, overburden strength, burial depth of the ore layer, length and width specifications of the working face, ore layer inclination, and structural development of the working face.

[0033] ② Use empirical formulas, formulas recommended by specifications, numerical analysis and other methods to preliminarily obtain the predicted height of the two-zone development of the ore layer. If there are measured data in the mines near the mining area, the data of the nearby mines can be used to predict the height of the two-zone development of the working face of the ore layer to be measured; or use the formula recommended in the "Specifications for Coal Pillar Retention and Compression Coal Mining in Buildings, Water Bodies, Railways and Main Shafts and Tunnels" jointly issued by the former State Administration of Work Safety, the former State Administration of Coal Mine Safety, the National Energy Administration, and the National Railway Administration in 2017 to predict the height of the two-zone development; or construct a numerical analysis model based on the working face conditions of the mining field to analyze and calculate the height of the two-zone development of the overburden; or use the calculation formula recommended in the "Coal Mine Water Prevention and Control Manual" to predict the height of the two-zone development.

[0034] ③ Determine the location of the tunnels in the working face of the mine and the location of the tunnels around the working face. If there is no tunnel in the working face of the mine, you can choose a location and construct a section of tunnels along the ore layer from the tunnel openings on both sides of the working face to the working face of the mine. The length of the tunnel entering the working face is not less than 20m. According to the overall layout of the working face tunnels, arrange underground directional monitoring boreholes. The drilling layout profile is as follows: Figure 1 , drilling arrangement section plane Figure 2As shown, the highest point of the directional drilling needs to be higher than the predicted maximum height of the two zones, generally higher than 5 times the thickness of the coal seam. The drilling opening point is in the tunnels on both sides of the working face of the stope, and the overall extension direction of the directional hole is to point to the working face cut and the connected tunnel on the opposite side. The directional hole trajectory first goes upward, bypassing the maximum position of the predicted height of the two zones, and then the drilling trajectory goes downward, finally exposing the tunnel in the working face.

[0035] ④ Carry out directional drilling construction, install and fix the distributed optical fiber in the hole and connect it to the monitoring system. The drilling is carried out according to the designed trajectory. The hole mouth casing is installed at the hole mouth, and the casing length is not less than 8m. After the hole is drilled through the surface tunnel, the hole tail casing is also installed at the end of the hole for about 8m, and then the optical fiber is installed into the hole by pulling back the distributed optical fiber. The method of pulling back the optical fiber is that the optical fiber is first placed in the surface tunnel at the bottom of the hole, the optical fiber is connected to the drill bit in the hole, and then the drill rod is pulled out of the hole. The optical fiber enters the borehole with the pulled drill bit. After the drill rod is completely pulled out of the borehole, the entire section of the distributed optical fiber is installed in the monitored directional borehole. Finally, slurry is used to grout the monitoring borehole, and the distributed optical fiber and the borehole surrounding rock are coupled into one through the slurry. The optical fiber at the borehole mouth is connected to the distributed monitoring equipment (generally BOTDR / A, i.e. distributed optical fiber demodulator, refer to invention ZL201410530675.7 Distributed optical fiber detection method for mining-induced overburden deformation), forming a mining field overburden deformation and damage monitoring system.

[0036] ⑤ Distributed optical fiber monitoring is carried out during the mining process of the working face to obtain relevant data. Data monitoring starts from the mining position of the working face 100m away from the tail end of the directional drilling, and ends when the mining of the working face reaches the opening point of the directional drilling. The monitoring frequency is no less than once a day.

[0037] ⑥ Analyze the height of the two zones of overburden according to the data. Through data analysis, the strain data of the overburden in the entire section of the monitoring drilling trajectory is obtained, and the deformation and damage of the overburden and the height of the development of the roof cracks are further analyzed to obtain the height of the two zones of the measured working face of the mining area.

[0038] The present invention adopts the method of directional drilling, and also realizes the consistency of the monitoring data collection order and the deformation and damage order of the working face in the well, which can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole arrangement method commonly used in the well. In addition, the installation of distributed optical fiber in directional drilling adopts the method of pulling back from the drill tail to the hole mouth, which can also effectively prevent the problem of optical fiber breakage caused by lowering the optical fiber from the hole mouth.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for monitoring the deformation and damage height of the overburden rock in a mining area, characterized in that: The following steps are involved: Step S1, collecting basic data of the working face of the stope to be tested; Step S2, using empirical formulas, formulas recommended by specifications, and numerical analysis methods to preliminarily obtain the predicted height of the development of two zones in the ore layer mining; If there are measured data in the mines near the mining area, the data of the nearby mines can be used to predict the height of the two zones of the working face of the ore layer to be measured; or a numerical analysis model can be constructed according to the working face conditions of the stope to analyze and calculate the height of the two zones of the overburden; Step S3, determining the position of the tunnels in the working face of the stope and the positions of the tunnels around the working face, and arranging underground directional monitoring drilling holes; If there is no tunnel in the working face of the mining area, a location is selected and a tunnel is constructed along the ore layer from the tunnel openings on both sides of the working face into the working face of the mining area. The length of the tunnel into the working face is not less than 20m. The underground directional monitoring drilling holes are arranged according to the overall layout of the working face tunnels. The highest point of the directional drilling hole must be higher than the predicted maximum height of the two zones, and the thickness of the coal seam must be higher than 5 times. The drilling opening point is in the tunnels on both sides of the working face of the stope. The overall extension direction of the directional hole is to point to the cutting eye of the working face and the tunnel in the opposite side. The trajectory of the directional hole first goes upward, bypassing the maximum position of the predicted height of the two zones, and then the drilling trajectory goes downward, finally exposing the tunnel in the working face. Step S4, perform directional drilling construction, install and fix the distributed optical fiber in the hole and connect it to the monitoring system; The drilling is carried out according to the designed trajectory, and the borehole casing is installed at the borehole mouth. The length of the casing is not less than 8m. After the borehole exposes the tunnel in the surface, the tail end casing of 8m is also installed at the tail end of the borehole. Then the optical fiber is installed into the hole by pulling back the distributed optical fiber. Finally, the monitoring borehole is grouted with slurry. The distributed optical fiber and the surrounding rock of the borehole are coupled into one through the slurry. The optical fiber at the borehole mouth is connected to the distributed monitoring equipment to form a monitoring system for deformation and damage of the overburden in the mining area. Step S5, distributed optical fiber monitoring during the mining process of the working face; Step S6: Obtain the development height of the two zones of overlying rock based on data analysis.

2. A method for monitoring the deformation and damage height of the overburden rock in a mining area as claimed in claim 1, characterized in that: In step S1, the basic data include mining thickness, mining technology, roof overburden structure, overburden lithology, overburden strength, ore layer burial depth, working face length and width specifications, ore layer inclination, and working face structural development.

3. A method for monitoring the deformation and damage height of the overburden rock in a mining area as claimed in claim 2, characterized in that: In step S4, the method of pulling back the optical fiber is that the optical fiber is first placed in a tunnel in the surface of the bottom of the hole, the optical fiber is connected to the drill bit in the hole, and then the hole is drilled and the drill rod is pulled out. The optical fiber enters the borehole with the pulled out drill bit. After the drill rod is completely pulled out of the borehole, the entire section of the distributed optical fiber is installed in the monitored directional borehole.

4. A method for monitoring the deformation and damage height of the overburden rock in a mining area as claimed in claim 3, characterized in that: In step S5, distributed optical fiber monitoring is performed during the working face recovery process to obtain relevant data. Data monitoring starts from the working face recovery position 100m away from the end of the directional drilling and ends when the working face is recovered to the directional drilling opening point. The monitoring frequency is no less than once a day.

5. A method for monitoring the deformation and damage height of the overburden rock in a mining area as claimed in claim 4, characterized in that: In step S6, the overburden strain data of the entire monitoring drilling trajectory is obtained through data analysis, and the deformation and damage of the overburden and the development height of the roof cracks are further analyzed to obtain the two-zone development height of the measured mining field working face.

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