A method for monitoring the damage depth of stope floor

Abstract

The present invention discloses a method for monitoring the depth of damage to the mining floor, including collecting basic data of the working face of the mining field to be tested; preliminarily obtaining the development depth of the damaged zone of the mining floor of the ore layer; determining the position of the tunnels in the working face of the mining field and the position of the tunnels around the working face, and designing underground directional monitoring boreholes; performing directional drilling construction, installing and fixing distributed optical fibers in the holes and connecting the monitoring system; carrying out distributed optical fiber monitoring during the mining process of the working face; and obtaining the development depth of the damaged zone of the mining floor according to 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 floor rock formation underground, which can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole layout method commonly used 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 mining floor damage depth monitoring, and in particular to a mining floor damage depth monitoring method. Background Art

[0002] Obtaining the depth data of the floor damage zone is crucial for floor water hazard prevention and control, and is an important basis for evaluating mining water prevention and control. Among them, the distributed optical fiber monitoring method has been widely used in recent years due to its real-time, continuous and sensitive monitoring advantages. Overall, the current method of arranging drilling site construction monitoring boreholes in the lower tunnel of the working face mining area is as follows: Figure 3 , the monitoring data is the most accurate, because from the time sequence, the floor damage develops gradually from the direct floor of the ore layer to the bottom. The floor drilling data collector is in the tunnel below the ore layer. It can use the optical fiber data monitoring and breakpoint monitoring functions in real time to see the development of the floor rupture from top to bottom. The monitoring process is consistent with the floor rock rupture process. However, this monitoring hole arrangement method has strict requirements on conditions. There must be a tunnel under the working face of the mining field. At present, it is generally only in high-gas mines that use bottom extraction tunnels for gas prevention and control. Few mines meet this condition.

[0003] The data obtained by the current method of setting up a drilling site and deploying monitoring boreholes in the tunnels on both sides of the working face or inside the working face has a big problem and cannot accurately indicate the depth of the development of the floor damage zone. The most commonly used underground monitoring boreholes are generally drilled in the tunnels on both sides of the working face or inside the face, and then arranged in the direction of the working floor and the working face cut. The maximum vertical height controlled by the borehole must exceed the maximum depth of the predicted development of the floor damage zone, such as Figure 4 As shown in the figure, since the destruction, deformation and rupture of the floor of the mining area are generally advanced, and the advanced area is not in a standard shape, it is easy to cause the development depth of the floor damage zone judged by monitoring data to be lower than the actual development depth. Figure 4 As shown in the figure, when mining reaches point A, a floor damage area is formed, and the outer line of the floor damage is shown in Figure 4 At this time, the distributed optical fiber arranged on the bottom plate contacts the bottom plate damage range for the first time at point B, and obvious strain changes will be monitored. At the same time, due to the severe deformation and damage of the rock formation at this location, the distributed optical fiber will be broken. The strain and breakpoint monitoring function of the optical fiber will determine a bottom plate damage depth H1, while the actual bottom plate damage depth is H2. However, since the rock formation deformation and damage at point B has caused the optical fiber to break, deeper data can no longer be monitored, resulting in an error between the optical fiber monitoring and the actual fracture depth.

[0004] Based on the above analysis, there are two main ways to arrange distributed optical fiber monitoring holes for mining floor damage. The overall monitoring accuracy is higher by using holes in the lower tunnels of the mining area, but there are few conditions for lower tunnels, so this hole arrangement method is rarely used. Currently, the extended method of arranging monitoring drill holes in the tunnels on both sides of the working face or inside is more widely used, but it is easy to cause errors in the monitoring results. Summary of the invention

[0005] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for monitoring the damage depth of the mining floor, which is essentially a method for laying underground monitoring holes, mainly using directional drilling technology to lay out drilling holes around the working surface to be tested underground or in the internal tunnels, and the drilling trajectory first goes downward to bypass the maximum position of the predicted floor damage depth, and then the drilling trajectory goes upward to finally expose the tunnel in the working surface, and finally the distributed optical fiber is installed in the whole 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 floor during the whole mining process of the ore layer. The optical fiber in the drilling section in the upward direction of the tail section of the drilling, the monitoring data acquisition is carried out from the bottom of the hole downward, which is consistent with the direction of deformation and damage of the mining floor. This method can realize the accurate monitoring of the floor damage depth using the distributed optical fiber method underground.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for monitoring the damage depth of a stope floor, comprising the following steps:

[0008] Step S1, collecting basic data of the working face of the stope to be tested;

[0009] Step S2, using empirical formulas, theoretical formulas, and numerical analysis methods to preliminarily obtain the development depth of the mining floor damage zone of the ore layer;

[0010] Step S3, determining the position of the tunnels in the working face of the stope and the position of the tunnels around the working face, and designing underground directional monitoring boreholes;

[0011] Step S4, perform directional drilling construction, install and fix the distributed optical fiber in the hole and connect it to the monitoring system;

[0012] Step S5, carrying out distributed optical fiber monitoring during the mining process of the working face;

[0013] Step S6: Obtain the development depth of the damaged zone of the stope floor according to data analysis.

[0014] Preferably, in step S1, the basic data include mining thickness, mining technology, floor rock structure, floor rock combination, floor rock strength, ore layer burial depth, working face length and width specifications, ore layer inclination, and working face structural development.

[0015] Preferably, in step S2, if there is measured data for a mine near the mining area, the data of the nearby mine is used to predict the floor damage depth 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 depth of the floor damage zone.

[0016] Preferably, in step S3, if there is no tunnel in the working face of the mine, a position can be selected to construct a section of tunnel 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, and the underground directional monitoring drilling holes are arranged according to the overall layout of the working face tunnels; the lowest point of the directional drilling holes must be lower than the predicted maximum depth of the development of the bottom plate damage zone, and the drilling opening points are in the tunnels on both sides of the working face of the mine. The overall extension direction of the directional holes is to point to the working face cut and the connected in-plane tunnels on the opposite side; the directional hole trajectory is designed to first be inclined downward to bypass the deepest position of the predicted development of the bottom plate damage zone, and then the drilling trajectory is inclined upward to finally pass through the tunnel in the working face.

[0017] Preferably, in step S4, the drilling is constructed according to the designed trajectory, and a hole mouth maintenance casing is installed at the hole mouth, the casing length is not less than 5m, and after the drilling exposes the tunnel in the surface, a hole tail maintenance casing of 5m is also installed at the tail section of the drilling, 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 floor deformation and damage monitoring system.

[0018] Preferably, in step S4, the method of pulling back the optical fiber is: 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 distributed optical fiber is also fully installed in the monitored directional borehole.

[0019] Preferably, in step S5, relevant data is obtained by monitoring, and data monitoring starts from the position where the working face is mined 100m away from the tail section of the directional drilling, and ends when the working face is mined to the position where the directional drilling opening point is, and the monitoring frequency is not less than once a day.

[0020] Preferably, in step S6, the strain data of the bottom rock strata of the entire monitoring drilling trajectory is obtained through data analysis, and the deformation and damage conditions of the bottom rock strata and the development depth of the damage zone are further analyzed to obtain the development depth of the bottom rock strata of the measured mining field working face.

[0021] The beneficial effects of the present invention are as follows: the core of the present invention is to adopt the method of directional drilling, which also realizes the consistency of the monitoring data collection order and the deformation and damage order of the bottom plate of the working face underground, and can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole arrangement method commonly used underground. 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

[0022] 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.

[0023] Figure 1 A cross-sectional view of a drilling arrangement provided for an embodiment of the present invention;

[0024] Figure 2 A plan view of a drilling arrangement provided for an embodiment of the present invention;

[0025] Figure 3 A cross-sectional view of the drilling method for monitoring the construction of the drilling site in the lower tunnel of the mining area in the prior art;

[0026] Figure 4 A profile diagram of monitoring drilling holes arranged in tunnels on both sides or inside the working face in the prior art. DETAILED DESCRIPTION

[0027] 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.

[0028] The present embodiment provides a method for monitoring the depth of floor damage in a mining area, comprising the following steps: ① collecting basic data of the working face of the mining area to be tested → ② using empirical formulas, theoretical formulas, numerical analysis and other methods to preliminarily obtain the development depth of the mining floor damage zone of 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 designing 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 conducting distributed optical fiber monitoring during the mining of the working face → ⑥ obtaining the development depth of the floor damage zone of the mining area based on data analysis.

[0029] ① Collect basic data of the working face of the mining area to be tested, including mining thickness, mining technology, floor rock structure, floor rock combination, floor rock 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.

[0030] ② Use empirical formulas, theoretical formulas, numerical analysis and other methods to preliminarily obtain the predicted depth of the development of the floor damage zone of 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 floor damage depth 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 mining area to analyze and calculate the development depth of the floor damage zone.

[0031] 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 layout plane Figure 2 As shown in the figure, the lowest point of the directional drilling needs to be lower than the maximum depth of the predicted floor damage zone, generally lower than 3 times the coal seam thickness, and 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 is designed to be inclined downward first, bypassing the deepest position of the predicted floor damage zone, and then the drilling trajectory is inclined upward, and finally passes through the tunnel in the working face.

[0032] 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, and the hole mouth maintenance casing is installed at the hole mouth. The length of the casing is not less than 5m. After the drilling exposes the in-face tunnel, the hole tail maintenance casing is also installed at the tail section of the drilling hole for about 5m, and then the optical fiber is installed in the hole by pulling back the distributed optical fiber. The way of pulling back the optical fiber is that the optical fiber is first placed in the in-face 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 distributed optical fiber is also fully installed in the monitored directional borehole. Finally, the monitoring borehole is grouted with slurry, and the distributed optical fiber and the surrounding rock of the borehole are coupled together 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) to form a deformation and damage monitoring system for the mining floor.

[0033] 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.

[0034] ⑥ Analyze the depth of the floor damage zone in the mining area based on the data. The strain data of the floor rock layer in the entire section of the monitoring drilling trajectory is obtained through data analysis, and the deformation and damage of the floor rock layer and the development depth of the damage zone are further analyzed to obtain the development depth of the floor damage zone of the working face of the mining area.

[0035] The core of the invention patent is to use the directional drilling method, which also achieves the consistency of the monitoring data collection order and the deformation and damage order of the bottom plate of the working face underground, which can solve the problem of inaccurate monitoring results caused by the current distributed optical fiber monitoring straight hole layout method commonly used underground. 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.

[0036] 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 damage depth of a stope floor, 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, theoretical formulas, and numerical analysis methods to preliminarily obtain the development depth of the mining floor damage zone 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 floor damage depth 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 development depth of the floor damage zone; Step S3, determining the position of the tunnels in the working face of the stope and the position of the tunnels around the working face, and designing underground directional monitoring boreholes; If there is no tunnel in the working face of the mining area, a position is selected, and a section of 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. According to the overall layout of the tunnels in the working face, underground directional monitoring drilling holes are arranged; the lowest point of the drilling hole must be lower than the maximum depth of the predicted development of the bottom plate damage zone, and the drilling hole opening point is in the tunnels on both sides of the working face of the mining area. The overall extension direction of the drilling hole is to point to the working face cut and the connected tunnel on the opposite side; the drilling trajectory is designed to be first inclined downward, bypassing the deepest position of the predicted development of the bottom plate damage zone, and then the drilling trajectory is inclined upward, and finally passes through the tunnel in the working face; Step S4, performing the drilling construction, installing and fixing the distributed optical fiber in the hole and connecting it to the monitoring system; The drilling is carried out according to the designed trajectory, and a hole mouth maintenance casing is installed at the hole mouth, and the casing length is not less than 5m. After the drilling exposes the tunnel in the surface, a hole tail maintenance casing of 5m 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, the borehole is grouted with slurry, and the distributed optical fiber and the surrounding rock of the borehole are coupled into one through the slurry, and the optical fiber at the borehole mouth is connected to the distributed monitoring equipment to form a deformation and damage monitoring system for the mining floor; Step S5, carrying out distributed optical fiber monitoring during the mining process of the working face; Relevant data shall be obtained through monitoring. Data monitoring shall start from the position of 100m from the end of the borehole when the working face is mined and end when the working face is mined to the position of the borehole opening point. The monitoring frequency shall be no less than once a day. Step S6: Obtain the development depth of the damaged zone of the stope floor according to data analysis.

2. A method for monitoring the damage depth of a stope floor as claimed in claim 1, characterized in that: In step S1, the basic data include mining thickness, mining technology, floor rock structure, floor rock combination, floor rock 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 damage depth of a stope floor as claimed in claim 1, characterized in that: In step S4, the method of pulling back the optical fiber is as follows: the optical fiber is first placed in the in-plane tunnel at 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 along with the pulled out drill bit. After the drill rod is completely pulled out of the borehole, the distributed optical fiber is also fully installed in the monitored borehole.

4. A method for monitoring the damage depth of a stope floor as claimed in claim 3, characterized in that: In step S6, the strain data of the bottom rock layer of the entire drilling trajectory is obtained through data analysis, and the deformation and damage of the bottom rock layer and the development depth of the damage zone are further analyzed to obtain the development depth of the bottom rock layer of the measured mining field working face.

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