A method for inverse analysis of stress field in deep coal mine working face

Abstract

The present application discloses a method for inversion analysis of stress field of deep coal mine working face, comprising the following steps: S1: arranging discrete stress measuring points: arranging discrete stress monitoring holes on the coal wall side for stress monitoring during the tunnel development stage; S2: arranging active optical fiber vibration sensor probes: arranging active optical fiber vibration sensor probes in developed tunnels to receive vibration waves actively excited during the excavation of undeveloped tunnels; S3: arranging passive optical fiber vibration sensor probes: arranging passive optical fiber vibration sensor probes in tunnels near the working face before the working face is advanced; S4: information collection and transmission; S5: inversion of three-dimensional stress field of the working face: correcting the stress field inversion result by receiving microseismic signals and scattered stress monitoring data generated during the advancement of the working face, and drawing a dynamic three-dimensional stress field of the working face; the present application realizes accurate inversion of stress field of deep high-stress working face and real-time monitoring of stress field of the working face.

Description

Technical Field

[0001] The present application relates to the field of coal mine working face stress field monitoring, and in particular to a deep coal mine working face stress field inversion analysis method. Background Art

[0002] After years of development, my country's coal mining has gradually extended to deeper areas. With the increase in depth, deep mining areas generally have high stress. After multiple geological actions, the surrounding rocks of deep tunnels are generally weak and broken. The contradiction between high stress and weak and broken surrounding rocks is prominent, which makes it very easy to have frequent mine earthquakes and roof disasters during deep coal resource mining, seriously hindering the mining of coal resources and the advancement of intelligentization.

[0003] By testing the stress state of the working face in deep tunnels, the stress state of the working face can be obtained, and the support strength and advancement speed can be adjusted in time to ensure the safe and efficient mining of coal resources. The current stress testing methods mainly include hydraulic fracturing, stress relief and rheological stress recovery. However, these stress testing methods are mostly based on point measurement, which is difficult to fully reflect the three-dimensional stress state of the working face.

[0004] During the development of the tunnel and the advancement of the working face, vibration waves will be generated artificially (blasting) or naturally (mine earthquakes). These vibration waves are collected by arranging receiving devices. The propagation speed of vibration waves in different surrounding rock states is different, which can be used to invert the state of the coal wall of the working face. Further, by analyzing the source mechanism of each microseismic event, the three-dimensional stress state of the working face can be obtained based on the damping stress inversion method. Although a more comprehensive working face stress state is obtained through inversion calculation, due to the influence of the on-site geological environment and engineering construction, the obtained stress field inversion results are often of low confidence, making it difficult to provide more effective guidance for on-site production and support. Summary of the invention

[0005] In order to solve the above problems, the embodiment of the present application provides a method for inversion analysis of the stress field of a deep coal mine working face, which can accurately guide the support and advancement speed of the working face during advancement, effectively avoid frequent mine earthquakes and roof disasters in a high-stress environment, and ensure safe and efficient production of deep high-stress coal resources. The technical solution is as follows:

[0006] The present application provides a method for inversion analysis of stress field of deep coal mine working face, comprising the following steps:

[0007] S1 Arrangement of discrete stress measuring points: During the tunnel development stage, discrete stress monitoring holes are arranged on the coal wall side for stress monitoring;

[0008] S2: Active fiber optic vibration sensor probes are deployed in the developed tunnels to receive the vibration waves actively excited during the excavation of the undeveloped tunnels.

[0009] S3: Deployment of passive optical fiber vibration sensor probes: Before the working face is advanced, passive optical fiber vibration sensor probes are deployed in the tunnels near the working face to receive the vibration waves spontaneously generated during the advancement of the working face;

[0010] S4 Information collection and transmission: Use optical fiber cables to connect discrete stress monitoring points and optical fiber microseismic monitoring systems that are linked to active and passive optical fiber vibration sensor probes to the downhole Ethernet switch, and connect to the uphole terminal equipment through signal transmission lines for information storage;

[0011] S5 working face three-dimensional stress field inversion: Taking the stress values ​​measured at discrete stress measuring points as constraints, the working face stress field is statically inverted using the collected actively excited microseismic data; the stress field inversion results are corrected by receiving the microseismic signals generated during the advancement of the working face and the changes in the scattered stress monitoring data, and the dynamic three-dimensional stress field of the working face is drawn.

[0012] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, the discrete stress test in S1 adopts the rheological stress recovery method, and uses a six-axis pressure sensor to monitor the absolute value of the working face stress.

[0013] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, the discrete stress measuring points in S1 are arranged on one side of the coal wall working face of the drift tunnel, the horizontal spacing of the measuring holes is 200m, the measuring hole depths are 0.75, 0.5, and 0.25 times the working face width, respectively, and the measuring hole diameter is not less than 110mm; when encountering special geological structures, additional stress measuring points are arranged around the special geological structures.

[0014] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, in S2, the spacing between active fiber optic vibration sensor probes is 10m, and the spacing between active wave excitation points is 8m, and the microseismic wave velocity data actively excited during excavation of undeveloped tunnels is collected.

[0015] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, the static stress field of the working face is inverted and analyzed by collecting actively excited microseismic wave velocity data and using the absolute stress value of the working face measured by the rheological stress recovery method as the boundary condition to obtain the initial stress distribution of the stress field.

[0016] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, the vibration waveform received by the vibration receiving point is preprocessed and the first arrival is picked up, and then the initial velocity model is established, and the three-dimensional velocity body result is inverted. The scattered point stress monitoring value is used as the boundary condition to perform an inversion analysis on the three-dimensional static stress state before the working face excavation.

[0017] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, in S3, as the working face advances forward, the passive fiber optic vibration sensor probe collects microseismic data generated by the working face roof and surrounding rock.

[0018] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, by collecting the time and velocity scatter points of the shock wave ray path, a grid is constructed and the rays are drawn within the grid, and a ray distribution density map and a wave velocity distribution cloud map are drawn.

[0019] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, in S4, the six-way pressure sensor is connected to the optical fiber demodulator through an optical fiber transmission line, and then connected to the underground Ethernet switch, the active optical fiber vibration sensor probe and the passive optical fiber vibration sensor probe are connected to the composite microseismic modulation and demodulation instrument through optical fiber connecting lines, and are connected to the Ethernet switch together, and then connected to the ground monitoring terminal through a signal transmission line to realize integrated monitoring and signal storage of stress and microseismic signals.

[0020] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, the dynamic three-dimensional stress field inversion method of the working face in S5 is: based on the wave velocity distribution cloud map, combined with the results obtained by active microseismic inversion analysis, the stress field changes during the working face advancement process are obtained, and the stress field inversion situation is corrected by the absolute stress values ​​measured by discrete stress measurement points, and finally the dynamic inversion results of the three-dimensional stress field of the working face during the working face advancement process are obtained.

[0021] The beneficial effects of a method for inversion analysis of the stress field of a deep coal mine working face provided by some embodiments of the present application are as follows: the present application uses active CT of vibration waves, and uses the absolute value of stress measured by discrete stress measuring points as boundary conditions, and can obtain the static three-dimensional stress state of the working face through inversion analysis. The microseismic wave velocity data generated during the advancement of the working face is collected by passive CT of vibration waves, and the dynamic three-dimensional stress state of the working face during the advancement is corrected in combination with the data of discrete stress measuring points. The present application combines the advantages of discrete measuring points and vibration wave inversion analysis, and can achieve accurate, comprehensive, and real-time stress state monitoring of the working face stress state by calibrating and correcting the inversion results based on the complete reflection of the stress field of the working face. On this basis, it can accurately guide the support and advancement speed during the advancement of the working face, effectively avoid frequent mine earthquakes and roof disasters in high-stress environments, and ensure safe and efficient production of deep high-stress coal resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a flow chart of the deep coal mine working face stress field inversion analysis method of the present application;

[0024] Figure 2 This is the first discrete stress measurement point arrangement diagram during trench excavation in this application;

[0025] Figure 3 is a disturbance stress recovery curve diagram of the rheological stress recovery method of the present application;

[0026] Figure 4 is a schematic diagram of the active microseismic monitoring arrangement of the present application;

[0027] Figure 5 is a flow chart of the active microseismic monitoring stress field inversion analysis of the present application;

[0028] Figure 6 is a schematic diagram of the passive microseismic monitoring arrangement of the present application;

[0029] Figure 7 is a flow chart of passive microseismic monitoring stress field inversion analysis of the present application;

[0030] Figure 8 This is a diagram of the integrated monitoring system of working face stress and microseismic signals of this application;

[0031] Fig. 9 It is a schematic diagram and a cross-sectional diagram of the dynamic three-dimensional stress field inversion results of the working face of this application. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] This application provides a deep coal mine working face stress field inversion analysis method, such as Figure 1 As shown, the construction time sequence includes the following steps:

[0035] S1 Arrangement of discrete stress measuring points: During the tunnel development stage, discrete stress monitoring holes are arranged on the coal wall side for stress monitoring;

[0036] S2: Active fiber optic vibration sensor probes are deployed in the developed tunnels to receive the vibration waves actively excited during the excavation of the undeveloped tunnels.

[0037] S3: Deployment of passive optical fiber vibration sensor probes: Before the working face is advanced, passive optical fiber vibration sensor probes are deployed in the lanes near the working face to receive the vibration waves spontaneously generated during the advancement of the working face;

[0038] S4 Information collection and transmission: Use optical fiber cables to connect discrete stress monitoring points and optical fiber microseismic monitoring systems that are linked to active and passive optical fiber vibration sensor probes to the downhole Ethernet switch, and connect to the uphole terminal equipment through signal transmission lines for information storage;

[0039] S5 working face three-dimensional stress field inversion: Taking the stress values ​​measured at discrete stress measuring points as constraints, the working face stress field is statically inverted using the collected actively excited microseismic data; the stress field inversion results are corrected by receiving the microseismic signals generated during the advancement of the working face and the changes in the scattered stress monitoring data, and the dynamic three-dimensional stress field of the working face is drawn.

[0040] The deep coal mine working face stress field inversion analysis method of the present application arranges discrete stress measuring points and shock wave active CT monitoring equipment in the trench development stage, and uses the discrete point stress monitoring results as boundary conditions to perform stress field inversion to obtain the static three-dimensional stress field of the working face; in the working face advancement stage, the shock wave passive CT monitoring equipment is arranged, and the dynamic three-dimensional stress field is obtained by correcting the discrete stress monitoring values. The present application realizes accurate inversion of the stress field of the deep high-stress working face and realizes real-time monitoring of the stress field of the working face.

[0041] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, Figure 2 As shown in the figure, during the first drift development stage, discrete stress measuring points are arranged on one side of the working face as the drift is developed.

[0042] Specifically, the discrete stress test adopts the rheological stress recovery method, with a horizontal spacing of 200m between the measuring holes, a depth of 0.75, 0.5, and 0.25 times the width of the working face, and a hole diameter of no less than 110mm. The six-axis stress sensor is placed deep in the measuring hole to monitor the absolute stress changes there. When encountering special geological structures (e.g., faults), additional measuring holes need to be arranged around them and additional six-axis stress sensors installed to monitor stress changes around the special geological structures.

[0043] The layout diagram of discrete stress measurement points during the first trench excavation of this application is as follows: Figure 2 As shown, Figure 2 In the figure, 1-1 is the working face, 1-2 is the fault in the working face, 1-3 is the first excavation trench, 1-4 is the opening of the cutting eye, 1-5 is the subsequent excavation trench, 2-1 is the discrete stress measuring hole, 2-2 is the six-directional stress sensor, 2-3 is the additional discrete stress measuring hole at the fault, and 2-4 is the additional six-directional stress sensor at the fault.

[0044] In actual monitoring, the absolute stress value change curve of the surrounding rock at the measuring point can be obtained, such as Figure 3 The disturbance stress test curve is shown. Figure 3 In the figure, 3-3 is the stress recovery stage, 3-4 is the disturbance enhancement stage, 3-5 is the yield stage, and 3-6 is the disturbance stress peak. When the working surface has not yet advanced, the stress recovery curve shows that it is fast at first and then slows down and gradually approaches the absolute stress. When the disturbance caused by the advancement of the working surface affects the sensor, the stress disturbance curve can be divided into the stress recovery stage, the disturbance enhancement stage and the yield stage, where the dividing point between the disturbance enhancement and the yield stage is the disturbance peak point.

[0045] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, Figure 4As shown in the figure, in the inversion analysis of the active CT stress field of the vibration wave, an active microseismic receiving device is arranged in the first excavation of the drift. The active microseismic receiving device uses an optical fiber vibration sensor probe to receive the vibration waves generated by the blasting points during the excavation of the subsequent drift. The spacing between the vibration receiving points is 10m, and the spacing between the active wave excitation points (blasting points) is 8m. The microseismic wave velocity data of active excitation (blasting) during the excavation of the undeveloped tunnel is collected.

[0046] Figure 4 is a schematic diagram of the active microseismic monitoring arrangement of this application, Figure 4 In the figure, 4-1 is an active optical fiber vibration sensing probe, 4-2 is a vibration wave excitation point, and 4-3 is an active wave path.

[0047] In a specific example, the initial stress distribution of the stress field is obtained by collecting the actively excited microseismic wave velocity data and using the absolute stress value of the working face measured by the rheological stress recovery method as the boundary condition to perform an inversion analysis on the working face stress field. Figure 5 As shown, Figure 5 This is the active microseismic monitoring stress field inversion analysis flow chart of this application. Figure 5 5-1 is waveform preprocessing and first arrival picking, 5-2 is the establishment of initial velocity model, and 5-3 is the three-dimensional velocity body inversion result.

[0048] Specifically, the vibration waveform received by the vibration receiving point is preprocessed and the first arrival is picked up, and then the initial velocity model is established, and the three-dimensional velocity body results are inverted. The scattered point stress monitoring values ​​are used as boundary conditions to perform inversion analysis on the static three-dimensional stress state before excavation of the working face.

[0049] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, Figure 6 As shown in the figure, in the inversion analysis of the seismic wave passive CT stress field, the passive optical fiber microseismic receiving device uses an optical fiber vibration sensor probe. As the working face advances, the microseismic data generated by the working face roof and surrounding rock are collected by the passive optical fiber vibration sensor probes arranged around the working face. Specifically, the passive optical fiber vibration sensor probes are arranged in a scattered manner in all directions of the working face, and then the microseismic signals generated during the mining process of the working face are collected from different directions. Figure 6 is a schematic diagram of the passive microseismic monitoring arrangement of this application, Figure 6 Middle: 6-1 is the passive optical fiber vibration sensor probe, 6-2 is the microseismic occurrence point, and 6-3 is the passive wave path.

[0050] like Figure 7 As shown, by collecting the time and velocity scatter points of the shock wave ray path, a grid is constructed and the rays are drawn in the grid, and a ray distribution density map and a wave velocity distribution cloud map are drawn. Figure 7 is a flow chart of passive microseismic monitoring stress field inversion analysis of the present application; Figure 7In the figure, 7-1 is the ray path time and velocity scatter points, 7-2 is the ray coverage and grid division, 7-3 is the ray distribution density, and 7-4 is the wave velocity distribution cloud map.

[0051] For example, in the deep coal mine working face stress field inversion analysis method provided in one embodiment, Figure 8 As shown in the figure, the integrated monitoring system of stress and microseismic signals of the working face is as follows: the six-way pressure sensor is connected to the optical fiber demodulator through an optical fiber transmission line, and then connected to the downhole Ethernet switch. The active optical fiber vibration sensor probe and the passive optical fiber vibration sensor probe are connected to the composite microseismic modulation and demodulation instrument through an optical fiber connection line, and are connected to the Ethernet switch together, and then connected to the ground monitoring terminal through a signal transmission line, so as to realize the integrated monitoring and signal storage of stress and microseismic signals.

[0052] Figure 8 This is a diagram of the integrated monitoring system of working face stress and microseismic signals of this application; Figure 8 In the figure: 8-1 is the spherical shell of the stress sensor, 8-2 is the pressure sensing point, 8-3 is the signal transmission rod, 8-4 is the optical fiber transmission line, 8-5 is the optical fiber demodulator, 8-6 is the active optical fiber vibration sensor probe, 8-7 is the passive optical fiber vibration sensor probe, 8-8 is the composite microseismic modulation and demodulation instrument, 8-9 is the Ethernet switch, 8-10 is the signal transmission line, and 8-11 is the signal acquisition terminal.

[0053] For example, in the deep coal mine working face stress field inversion analysis method provided in an embodiment, the working face dynamic three-dimensional stress field inversion method is specifically as follows: based on the wave velocity distribution cloud map, combined with the results obtained by active vibration wave CT inversion analysis, the stress field change during the working face advancement process is obtained, and the stress field inversion situation is corrected by the absolute stress value measured by the discrete stress measurement point, and finally a relatively accurate dynamic inversion result of the three-dimensional stress field of the working face during the working face advancement process is obtained. The dynamic inversion result of the three-dimensional stress field of the working face is as follows: Fig. 9 shown.

[0054] Fig. 9 It is a schematic diagram and a cross-sectional diagram of the inversion results of the dynamic three-dimensional stress field of the working face of this application, Fig. 9 Middle: 9-1 is the inverted three-dimensional dynamic stress field, 9-2 is the longitudinal profile of the stress field, and 9-3 is the transverse profile of the stress field. The inversion results of the stress field can be used for profile analysis. By analyzing the transverse and longitudinal profiles, the stress distribution and stress value in the profile can be clearly displayed. This can achieve accurate, comprehensive, and real-time stress state monitoring of the working face. On this basis, the support and advancement speed during the advancement of the working face can be accurately guided, and frequent mine earthquakes and roof disasters in high-stress environments can be effectively avoided, ensuring safe and efficient production of deep high-stress coal resources.

[0055] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes, and it can be fully applicable to various fields suitable for the present application. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for inversion analysis of stress field of deep coal mine working face, characterized in that: The following steps are involved: S1 Arrangement of discrete stress measuring points: During the tunnel development stage, discrete stress monitoring holes are arranged on the coal wall side for stress monitoring; S2: Active fiber optic vibration sensor probes are deployed in the developed tunnels to receive the vibration waves actively excited during the excavation of the undeveloped tunnels. S3: Deployment of passive optical fiber vibration sensor probes: Before the working face is advanced, passive optical fiber vibration sensor probes are deployed in the tunnels near the working face to receive the vibration waves spontaneously generated during the advancement of the working face; S4 Information collection and transmission: Use optical fiber cables to connect discrete stress monitoring points and optical fiber microseismic monitoring systems that are linked to active optical fiber vibration sensor probes and passive optical fiber vibration sensor probes to downhole Ethernet switches, and connect to uphole terminal equipment through signal transmission lines for information storage; S5 Three-dimensional stress field inversion of working face: Using the stress values ​​measured at discrete stress measuring points as constraints, the actively excited microseismic data collected are used to perform static inversion of the stress field of the working face; By receiving the microseismic signals generated during the advancement of the working face and the changes in the scattered stress monitoring data, the stress field inversion results are corrected and the dynamic three-dimensional stress field of the working face is drawn; The discrete stress test in S1 adopts the rheological stress recovery method and uses a six-axis pressure sensor to monitor the absolute value of the stress on the working surface; The discrete stress measuring points in S1 are arranged on one side of the coal wall working face of the drift tunnel, with a horizontal spacing of 200m between the measuring holes, and the measuring hole depths are 0.75, 0.5, and 0.25 times the working face width, respectively, and the measuring hole diameter is not less than 110mm; when encountering special geological structures, additional stress measuring points are arranged around the special geological structures; In S2, the distance between active optical fiber vibration sensor probes is 10m, and the distance between active wave excitation points is 8m, so as to collect the microseismic wave velocity data actively excited during excavation of undeveloped tunnels; The static stress field of the working face is inverted by collecting the actively excited microseismic wave velocity data and using the absolute stress value of the working face measured by the rheological stress recovery method as the boundary condition to obtain the initial stress distribution of the stress field. The vibration waveform received by the vibration receiving point is preprocessed and the first arrival is picked up. Then the initial velocity model is established, the three-dimensional velocity body result is inverted, and the three-dimensional static stress state before the excavation of the working face is inverted using the scattered stress monitoring value as the boundary condition; In S3, as the working face advances, the passive optical fiber vibration sensor probe collects microseismic data generated by the working face roof and surrounding rock; By collecting the time and velocity scatter points of the shock wave ray path, a grid is constructed and the rays are drawn in the grid, and a ray distribution density map and a wave velocity distribution cloud map are drawn; In S4, the six-way pressure sensor is connected to the optical fiber demodulator through an optical fiber transmission line, and then connected to the downhole Ethernet switch. The active optical fiber vibration sensor probe and the passive optical fiber vibration sensor probe are connected to the composite microseismic modulation and demodulation instrument through an optical fiber connection line, and are connected to the Ethernet switch together, and then connected to the ground monitoring terminal through a signal transmission line, so as to realize the integrated monitoring and signal storage of stress and microseismic signals; The dynamic three-dimensional stress field inversion method of the working face in S5 is as follows: based on the wave velocity distribution cloud map, combined with the results obtained by active microseismic inversion analysis, the stress field changes during the advancement of the working face are obtained, and the stress field inversion is corrected by the absolute stress values ​​measured by discrete stress measuring points, and finally the dynamic inversion results of the three-dimensional stress field of the working face during the advancement of the working face are obtained.

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