Mining-while-digging earthquake advanced detection system based on distributed optical fiber acoustic sensing

Abstract

The invention discloses a mining-while-digging earthquake advanced detection system based on distributed optical fiber acoustic sensing. Relates to the technical field of seismic exploration. On the basis of a distributed optical fiber acoustic sensing technology, mining-while-digging seismic detection of a working face is realized by utilizing vibration generated by cutting a coal rock stratum by mining machinery. In the production process, the detector collects vibration data of mining machinery and transmits the vibration data to the server through a network; optical cables are arranged on two sides of a coal face upper and lower crossheading or two sides of a driving face roadway; the demodulator emits pulse laser and transmits the pulse laser to the working face optical cable through the industrial looped network or the independent fiber core, vibration of measuring points at equal intervals of the optical cable is measured, and a measuring data packet is returned to the demodulator through the industrial looped network or the independent fiber core; the demodulator demodulates vibration waveform data and uploads the vibration waveform data to the server; server data processing software carries out noise reduction processing on the waveform, then stores and images the waveform, carries out real-time intelligent interpretation, and realizes detection of a geological structure and an abnormal area in front of a working face.

Description

Technical Field

[0001] The present invention relates to the field of seismic exploration technology, and in particular to a mining-as-you-dig seismic advance detection system based on distributed optical fiber acoustic sensing. Background Art

[0002] With the in-depth exploration and development of underground mineral resources, as well as the practical needs of energy, transportation, water conservancy, and military projects, underground mining projects have expanded on a large scale. The frequency of crossing high-risk geological areas such as fault zones, water-rich areas, and stress-variable zones continues to increase. As mining projects progress, accurate and efficient perception of the geological structure and spatial changes in the stratigraphic structure ahead of the working face is needed. Dynamically constructing a high-precision, transparent geological model guides the adaptive operation of mining equipment, enabling intelligent mining with minimal or no personnel at the underground working face.

[0003] Currently, geophysical exploration methods for underground mining working faces include electromagnetic and seismic methods. Electromagnetic methods primarily include downhole transient electromagnetic, direct current, geological radar, and radio-electromagnetic perspective. Seismic methods include channel wave seismic exploration, TSP, TRT, and in-process seismic exploration. These methods have the following limitations: (1) Electromagnetic methods: Transient electromagnetic and direct current methods are sensitive to low-resistance water-rich areas, while geological radar and radio electromagnetic wave perspective are sensitive to geological structures with different electrical properties. However, these electromagnetic methods are strongly interfered with by underground metal mechanical equipment and anchor rod and anchor net support, resulting in large errors.

[0004] (2) Seismic methods: Slot wave seismic exploration and TSP methods generally use explosive sources. Although they have strong energy and long detection distance, the operation of underground explosive construction is complicated, the safety is poor, and it is destructive to the tunnel support. The TRT method uses a hammer source, which avoids the shortcomings of the explosive source, but the manual hammering workload is large, the quality is difficult to guarantee, and the hammering energy is not large, resulting in a short detection distance. More importantly, these methods need to be carried out when coal mining or tunneling stops, which affects production, the data collection cost is high, and continuous monitoring cannot be achieved. Mining and excavation seismic detection, by using the vibration generated by the cutting of mining machinery as the source, avoids the weaknesses of the unsafe explosive source and the low energy of the hammer source, and has little interference with mining work. However, this type of method currently mainly uses traditional cable seismometers for data collection, and there are the following problems in normalized applications: 1) Construction and maintenance are complex, instrument costs are high, and it is difficult to achieve high-density seismic acquisition. Complete spatial wavefield information of the working face cannot be obtained, resulting in the inability to use high-resolution full-wavefield imaging methods, which affects the resolution of seismic detection during mining.

[0005] 2) The measured seismic data is discontinuous and has poor real-time performance.

[0006] 3) As the tunnel advances or the working face is mined, the detectors move away from the earthquake source or are damaged by the mining process. Manual movement of the detector array is required, which further increases the detection cost and cannot achieve real-time monitoring of the geological conditions that change with the mining process. Summary of the Invention

[0007] In view of the above problems, the present invention proposes a mining-as-you-dig seismic advance detection system based on distributed fiber optic acoustic sensing.

[0008] The embodiment of the present invention provides a mining-as-you-go seismic advance detection system based on distributed optical fiber acoustic sensing, comprising: a detector, an optical cable, a demodulator, and a server; The geophone is mounted on a mining machine and is used to collect vibration data of a mining machine seismic source and transmit it to the server, wherein the mining machine seismic source is vibration generated when the mining machine cuts a coal layer. The mining machine includes: a shearer at a coal mining face or a tunneling machine or a tunneling anchoring machine at a tunneling face; The optical cable is tightly coupled to the tunnel wall of the working face and is used to sense the vibration of the mining machinery source at equally spaced points; The demodulator is connected to the optical cable and is used to measure the vibration sensed by the optical cable to obtain measurement data, demodulate the measurement data to obtain corresponding vibration data, and then transmit it to the server; The server is used to receive full-space wavefield data in real time and detect geological structures, stratum morphological changes and abnormal areas in front of the working face based on the full-space wavefield data. The full-space wavefield data includes vibration data from the detector and vibration data from the demodulator.

[0009] Optionally, the detector is a vibration detector of various forms.

[0010] Optionally, at the coal mining face, the detector is installed inside the drum of the coal mining machine or at a position where the front and rear rocker arms of the coal mining machine are close to the drum; The geophone collects vibration data of the shearer's seismic source and transmits the data to the server via the network; The detector is connected to the power supply of the coal mining machine and has a built-in battery.

[0011] Optionally, at the excavation working face, the geophone is installed at a position of the excavator close to the blasting head; The geophone collects vibration data of the tunnel boring machine's earthquake source and transmits the data to the server via the network; The detector is connected to the power supply of the tunnel boring machine and has a built-in battery.

[0012] Optionally, at the coal mining face, the optical cable is laid on the roadway walls of the upper and lower drifts of the coal mining face and is tightly coupled with the roadway walls; The optical cable is pre-buried and laid together with the support construction during tunnel excavation when the working face is excavated up and down the trench, or is pre-buried and laid uniformly before the coal mining working face is mined; The optical cable is connected to a dedicated fiber core of the mine industrial ring network at the working face exit, or the optical cable is connected to a switch of the mine industrial ring network through a dedicated demodulator-switch integrated machine at the working face exit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face; After the optical cable is laid, as the coal mining process progresses, the optical cable near the working face is cut, and a knot or optical extinction operation is performed at the break point of the optical cable to reduce noise at the broken end; After the optical cable is laid, as the coal mining process progresses, the optical cable on the tunnel wall away from the working face naturally extends into the goaf to monitor the goaf.

[0013] Optionally, at the excavation working face, the optical cables are laid on both sides of the excavation tunnel, tightly coupled with the tunnel sides, and well marked; During the construction of support for excavation of the working face, the optical cables on both sides of the excavation tunnel are pre-buried and laid together. If there are special circumstances, the optical cables on only one side of the tunnel are laid. In the case of laying the optical cables on only one side of the tunnel, the tunnel side close to the coal mining working face is preferred; The optical cable is connected to the dedicated fiber core of the mine industrial ring network at the working face exit, or the optical cable is connected to the switch of the mine industrial ring network through a dedicated demodulator-switch integrated machine at the working face exit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face.

[0014] Optionally, the process of the demodulator measuring the vibration sensed by the optical cable to obtain measurement data includes: The demodulator emits a pulsed laser and transmits it to the optical cable through an industrial ring network or an independent fiber core. The vibration of the corresponding equally spaced points of the optical cable is measured using the Rayleigh scattering effect, and the measured Rayleigh scattering signal is returned to the demodulator through the industrial ring network or the independent fiber core. The demodulator demodulates the vibration waveform data and transmits it to the server.

[0015] Optionally, during the laying process of the optical cable, different fixing methods are selected according to different internal support forms of the tunnel. The fixing methods include: first fixing the optical cable on the tunnel wall using a first fixing method, laying an anchor net, and then bonding the optical cable to the tunnel wall using cement spraying. The first fixing method includes: dense clips; or It is laid inside the anchor net using a second fixing method, in direct contact with the tunnel wall. The second fixing method includes: gypsum fixing, spraying fixing, and polymer material fixing; The optical cable should be laid straight, tight and parallel to the tunnel floor.

[0016] Optionally, the parameters that need to be recorded during the optical cable laying process include: The relationship between the length of the optical cable and the absolute coordinates of the roadway; The extension length of each optical cable from the demodulator and its corresponding relationship with the coordinates of the center line of the roadway; The height of each optical cable relative to the tunnel floor; The types of tunnels in which the optical cables are installed include: heading tunnels and coal mining tunnels.

[0017] Optionally, the method for the server to detect geological structures, stratum morphological changes and abnormal areas in front of the working face based on the full-space wavefield data includes: Preprocessing the vibration data from the detector and the vibration data from the demodulator to obtain high-quality data; High-resolution imaging technology and full waveform inversion technology are used to process high-quality data or target data to obtain imaging results of the geological structure and wave velocity anomaly areas in front of the mining working face. The target data is the data obtained by pre-processing the vibration data from the demodulator; Processing the high-quality data or the target data using a diffraction wave imaging method to obtain imaging results of the geological structure and abnormal body conditions in front of the mining working face; Based on the dispersion inversion algorithm of passive source background noise, the characteristics of distributed optical fiber high-density acquisition are utilized, and the frequency Bessel transform method is adopted to extract the dispersion curves of fundamental and high-order surface waves from the high-quality data or the target data. Then, the surface wave dispersion analysis method is used for inversion to obtain information on the abnormal phase velocity areas in the surrounding rock in front of the mining working face and on both sides of the roadway; Based on the imaging results, artificial intelligence methods are used to analyze and identify the structures of faults, folds, fracture zones, collapse columns, voids, igneous rocks, coal-rock interfaces, and roadway roof and floor undulations; Processing the high-quality data or the target data using a passive source method to invert and obtain temporal variation data of physical parameters of the tunnel structure and different locations within the mining working face, the physical parameters including wave velocity, resonance frequency, elastic modulus, and attenuation coefficient; Utilizing the target data, monitoring the wave velocity variation data and microseismic data of the rock mass surrounding the roadway or the coal body to be mined over time, analyzing the changes in the physical properties of the roadway surrounding rock or the coal body to be mined at different time scales, inferring the corresponding stress changes generated by the mining process, combining microseismic monitoring and positioning to infer the development of new fractures generated by the mining process, and integrating various monitoring data to analyze, investigate, and predict hidden geological disaster factors in the mining process; The pre-processing specifically includes: Based on the noise signals recorded when the mining machinery is not in motion but other equipment in the tunnel is in motion, the vibration data collected during the cutting of the mining machinery is adaptively filtered and denoised to obtain the vibration data of the mining machinery source with a high signal-to-noise ratio. The other equipment includes: crushers and belt conveyors; Performing spatial integration on the vibration data from the demodulator to obtain vibration data of the demodulator with a high signal-to-noise ratio; Combining the vibration data and precise positioning of the mining machinery source, coherent deconvolution, Wiener filtering, fk filtering and adaptive gain control are performed based on similarity signals to extract reflected seismic wavelets from the high-quality data or the target data.

[0018] The present invention's distributed fiber-optic acoustic sensing-based, in-process seismic advance detection system comprises a geophone, an optical cable, a demodulator, and a server. During production, the geophone collects vibration data from mining machinery and transmits it to the server via a network. The optical cable is tightly coupled to the tunnel walls of the working face, sensing the vibrations of the mining machinery's seismic sources at evenly spaced points. The demodulator measures the vibrations at evenly spaced measurement points on the optical cable and returns the measurement data packets to the demodulator. The demodulator demodulates the vibration waveform data and uploads it to the server. The server receives full-space wavefield data in real time and, based on this data, detects geological structures, changes in stratum morphology, and abnormal areas ahead of the working face.

[0019] This invention addresses the shortcomings of various traditional geophysical exploration methods, particularly the problems with the regular application of cable-type seismometers for on-the-go seismic detection. It creatively introduces a distributed fiber-optic acoustic sensing system into an integrated on-the-go seismic detection and monitoring system. Based on distributed fiber-optic acoustic sensing technology, it utilizes the vibrations generated by mining machinery cutting coal and rock layers to achieve on-the-go seismic detection at the working face. This system has the following advantages: (1) The entire system utilizes the emerging cutting-edge distributed fiber acoustic sensing (DAS) technology and optical cables arranged close to the coal wall. It can collect full wavefield information of the mine space at a high density of N meters (for example, 0.5 meters, 1 meter), which helps to separate various seismic phases and diffraction waves and scattered wave fields, and improve the resolution of advance detection during mining for different advance detection targets.

[0020] (2) The entire system uses the vibration signals generated by the coal mining machine and the tunnel boring machine when cutting coal and rock as the seismic source, and places detectors on the coal mining machine and the tunnel boring machine to record the seismic source signals in real time, which can provide accurate seismic source information for the coherent deconvolution of the wave field, so as to improve the pulse effect of the seismic source during mining and tunneling, and thus improve the resolution of advanced detection.

[0021] (3) After the entire system is laid out, there is no need to move the distributed optical cable, and maintenance is simple for underground workers.

[0022] (4) The equipment used in the entire system is powered by normal power supply and does not need to be charged in the well or can last for several days on a single charge, ensuring the normal operation of the system.

[0023] (5) If a seismic detection system is constructed while excavating and optical cables are pre-buried, the pre-buried optical cables can be reused at the working face to directly form a seismic detection system while mining, without the need for repeated construction. In addition, the pre-buried optical cables can also provide seismic detector functions for channel wave detection before mining at the working face, further saving geophysical exploration costs.

[0024] (6) The pre-buried optical cable can also naturally enter the goaf as the mining process progresses, forming a goaf monitoring system, providing an effective tool for goaf microseismic monitoring, water accumulation monitoring, and goaf stress monitoring.

[0025] (7) By making full use of the advantages of real-time and high-density data collection, it is possible to monitor the changes in geological structures and geological properties over time during the mining process with high sensitivity, and timely discover hidden disaster-causing factors such as stress concentration, crack development, and water channels caused by the mining process. The hidden disaster-causing factors can be checked and warned through the artificial intelligence system.

[0026] (8) Compared with the existing advance detection method based on traditional seismic detectors during mining and excavation, the method adopted by the system proposed in the present invention increases the spatial density of seismic data acquisition, improves the real-time and continuity of acquisition, and reduces the cost of data acquisition and instrument maintenance; it combines high-density continuous seismic acquisition with full-wavefield seismic imaging methods to improve the resolution, accuracy and real-time performance of detection during mining and excavation.

[0027] (9) Compared with artificial source seismic detection methods such as slot waves, TSP, and TRT, the method adopted by the system proposed in the present invention has high data acquisition density, continuous time, and high imaging resolution; it does not require explosive sources or manual hammering, which improves safety and reduces construction costs; it does not affect the normal progress of mining work and can be detected simultaneously during the mining process; it can continuously monitor geological structure changes and wave velocity anomalies caused by the mining process.

[0028] (10) Compared with underground transient electromagnetic, pit penetration, geological radar and other electromagnetic methods, the method adopted by the system proposed in the present invention is not subject to interference from underground metal equipment, has a long detection distance, and is more sensitive to geological structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings: Figure 1 is a schematic structural diagram of an exemplary geophone installed on a coal mining machine in an embodiment of the present invention; Figure 2 This is a schematic diagram of an exemplary arrangement of a mining and excavation seismic advance detection system deployed in a coal mining face and an excavation face in an embodiment of the present invention; Figure 3 1 is a schematic diagram of an exemplary arrangement of a mining-as-you-go seismic advance detection system for a coal mining face in an embodiment of the present invention; Figure 4 It is a schematic diagram of the layout of an exemplary seismic advance detection system for mining and excavation on a tunneling working face in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention, are only part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the present invention.

[0031] The present invention proposes a distributed fiber-optic acoustic sensing-based, in-process seismic advance detection system, comprising a geophone, an optical cable, a demodulator, and a server. The geophone is mounted on a mining machine and collects vibration data from the machine's seismic source, generated by the machine cutting through coal and rock formations, and transmits this data to the server. The seismic source is the vibration generated by the machine cutting through coal and rock formations. The mining machine includes a shearer at a mining face, a roadheader at a tunneling face, or a combined drilling and anchoring machine.

[0032] The optical cable is tightly coupled to the tunnel walls of the working face, sensing vibrations from the mining machinery at evenly spaced points. Because the optical cable needs to be laid throughout the entire tunnel wall, it is distributed. This tightly coupled distribution ensures reliable and stable vibration signal acquisition. Based on their installation location, the geophones collect vibration data at the source, while the vibrations sensed by the optical cable can be considered vibrations in the coal and rock formations caused by the source vibrations. If the mining machinery source is considered a central earthquake source, then the geophones collect data from the central source, while the optical cable collects data from seismic waves emanating from it.

[0033] The demodulator is connected to the optical cable and is used to measure the vibration sensed by the optical cable to obtain measurement data, demodulate the measurement data to obtain the corresponding vibration data, and then transmit it to the server; the server is used to receive full-space wavefield data in real time, and detect the geological structure, stratum morphology changes and abnormal areas in front of the working face based on the full-space wavefield data. The full-space wavefield data includes: vibration data from the detector and vibration data from the demodulator.

[0034] In one embodiment of the present invention, the geophone is a vibration geophone of various forms. Preferably, a dynamic coil or MEMS-based vibration geophone is selected. Of course, other forms of vibration geophones are also suitable, as long as they can be installed on the mining machinery.

[0035] Coal mining typically involves a mining face and a tunneling face. The installation locations of geophones and optical cables differ slightly between these two faces. In the mining face, geophones are installed inside the shearer drum or near the drum on the front and rear arms of the shearer. The geophones collect vibration data from the shearer's seismic source and transmit it to a server via the network. The geophones are connected to the shearer's power supply and have internal batteries.

[0036] For example: Refer to Figure 1 The schematic diagram of an exemplary detector installed in a coal mining machine is shown. The coal mining machine generally has a front drum and a rear drum. Figure 1 The diagram shows a geophone installed inside two drums: the front drum and the rear drum. Both geophones are connected to a data acquisition base station via a data cable to exchange vibration data. The base station then transmits the data to a ground server via the network. The geophones are connected to the shearer's power supply and have internal batteries, providing a dual backup mode of power supply (mains power supply) and internal battery. If the geophones cannot be installed inside the drums, they should be mounted on the rocker arm close to the drums or on the shearer body. The principle is that the closer the geophones are to the drums, the more accurate the vibration data collected.

[0037] Similarly, at the tunneling face, a geophone is installed near the blasting head of the TBM. It collects vibration data from the TBM's seismic source and transmits it to a server via the network. The geophone is connected to the TBM's power supply and has a built-in battery. Considering the actual site conditions, the TBM's geophone can be installed in a convenient location. However, it should be noted that the closer it is to the blasting head, the more accurate the vibration data obtained.

[0038] At the coal mining face, the optical cable is laid on the tunnel walls of the upper and lower drifts of the coal mining face and is tightly coupled with the tunnel walls; the optical cable is pre-buried and laid together with the support construction during the tunnel excavation when the upper and lower drifts of the working face are excavated, or it is pre-buried and laid uniformly before the coal mining face is mined.

[0039] The optical cable is connected to the dedicated fiber core of the mine industrial ring network at the working face exit, or the optical cable is connected to the switch of the mine industrial ring network through a dedicated demodulator-switch at the working face exit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face; after the optical cable is laid, as the coal mining process advances, the optical cable close to the working face is cut, and knotting or extinction operations are performed at the break point of the optical cable to reduce the noise of the broken end; after the optical cable is laid, as the coal mining process advances, the optical cable on the tunnel wall away from the working face naturally extends into the goaf to monitor the goaf.

[0040] Whether in the coal mining face or the tunneling face, during the laying process of optical cables, different fixing methods are selected according to the different internal support forms of the tunnel. The fixing methods include: first using the first fixing method to fix the optical cable to the tunnel wall, laying the anchor net, and then using cement spraying to bond the optical cable to the tunnel wall. The first fixing method includes: dense clips, or a fixing method similar to dense clips that can fix the optical cable to the tunnel wall; if cement spraying cannot be used, the second fixing method is used to lay the optical cable inside the anchor net, in direct contact with the tunnel wall. The second fixing method includes: gypsum fixing, spraying fixing, polymer material fixing, and other similar fixing methods. The optical cable should be laid straight, tight, and parallel to the tunnel floor.

[0041] Both the demodulator and the server can be deployed in the ground computer room. To ensure the normal maintenance-free operation of the system, the demodulator and the server use a dual backup mode of normal power supply and built-in battery power supply.

[0042] In order to better understand the above-mentioned seismic advance detection system deployed in the coal mining face, refer to Figure 2 The figure shows an exemplary layout diagram of a seismic advance detection system for mining and excavation at a coal mining face and an excavation face. Figure 2The left side of the black vertical line is a schematic diagram of the layout of the seismic advance detection system for the coal mining face; the right side of the black vertical line is a schematic diagram of the layout of the seismic advance detection system for the tunneling face. Figure 3 and Figure 4 Shown.

[0043] Reference Figure 3 The figure shows a schematic diagram of the layout of an exemplary seismic advance detection system for mining and excavation in a coal mining face. Figure 3 In the mining area, optical cables are laid close to the cut-hole side of the chute, tightly coupled to the coal wall. Optical cables are laid on the opposite side of the cut-hole side of the chute, deep into the goaf. The goaf monitoring system collects and monitors vibration data from the goaf. The on-site mining monitoring system also collects and monitors vibration data from the mining area. All data is sent to a demodulator on the surface, processed by the demodulator, and then transmitted to a server for further processing.

[0044] For the excavation working face, optical cables are laid on both sides of the excavation tunnel, tightly coupled with the tunnel walls, and well marked. During the excavation support construction of the working face, the optical cables on both sides of the excavation tunnel are pre-buried and laid together. If there are special restrictions, for example: one side of the tunnel wall cannot lay optical cables, then only the optical cables on one side of the tunnel wall are laid. Among them, when laying optical cables on only one side of the tunnel wall, the tunnel wall close to the coal mining working face is preferred for laying, which is convenient for subsequent detection and reuse. At the working face exit, the optical cable is connected to the dedicated fiber core of the mine industrial ring network. Alternatively, at the working face exit, the optical cable is connected to the switch of the mine industrial ring network through a dedicated demodulator and switch. The signal is exported to the demodulator, forming an optical cable distributed measurement system surrounding the working face.

[0045] In order to better understand the above-mentioned seismic advance detection system deployed at the excavation working face, refer to Figure 4 The figure shows a schematic diagram of the layout of an exemplary seismic advance detection system for mining and excavation on a tunneling working face. Figure 4 The diagram shows an example of a roadheader and its mounted detector. Straight-coupled and / or coiled optical cables can be used to tightly couple the tunnel walls. At the working face exit, the optical cable connects to a dedicated fiber core in the mine's industrial ring network. Alternatively, the optical cable connects to a switch in the mine's industrial ring network via a dedicated integrated demodulator / switch at the working face exit, exporting the signal to a surface demodulator.

[0046] In one embodiment of the present invention, a demodulator serves as the core device for distributed fiber-optic acoustic sensing. The demodulator measures the vibrations sensed by the optical cable to obtain measurement data. The demodulator emits a pulsed laser, which is transmitted to the optical cable via an industrial ring network or an independent fiber core. The laser then uses the Rayleigh scattering effect to measure the vibrations at equally spaced points on the optical cable. The measured Rayleigh scattering signals are then returned to the demodulator via the industrial ring network or the independent fiber core. After the demodulator demodulates the vibration waveform data, it uploads it to a server, enabling high-density measurements at intervals as low as 1 meter.

[0047] In addition, the parameters that need to be recorded during the optical cable laying process include: the relationship between the optical cable length and the absolute coordinates of the tunnel; the extended length value of each optical cable from the demodulator, and its corresponding relationship with the coordinates of the tunnel centerline; the height of each optical cable relative to the tunnel floor; the type of tunnel where each optical cable is installed, which includes: heading tunnel and coal mining tunnel.

[0048] The workflow of the mining-as-you-dig seismic advance detection system based on distributed fiber optic acoustic sensing can be summarized as follows: During the production process, the detector collects vibration data of the mining machinery and transmits it to the server through the network; the demodulator emits a pulsed laser and transmits it to the working face optical cable through an industrial ring network or an independent fiber core, measures the vibration of equally spaced measuring points on the optical cable, and returns the measured Rayleigh scattering signal to the demodulator through the industrial ring network or the independent fiber core; the demodulator demodulates the vibration waveform data and uploads it to the server; the server stores the waveform after noise reduction processing, and intelligently interprets it in real time to realize the detection of geological structures and abnormal areas in front of the working face.

[0049] In one embodiment of the present invention, the server detects the geological structure, stratum morphology changes, and abnormal areas ahead of the working face based on full-space wavefield data. Preferably, data processing software can be deployed in the server to receive the transmitted tunnel full-wavefield data in real time, and use the data processing software to perform data noise reduction processing, imaging, and geological interpretation. The data processing software stores the waveform after noise reduction processing and performs real-time intelligent interpretation to achieve the detection of geological structure, stratum morphology changes, and abnormal areas ahead of the working face. In addition, due to the laying of optical cables, it can not only sense the vibrations generated by mining machinery, but also the mine pressure, microseismicity, hydrology, etc. during the mining process. Therefore, with the help of this, the server can achieve real-time monitoring and intelligent interpretation of changes in mine pressure, microseismicity, hydrology, etc. during the mining process.

[0050] In one embodiment of the present invention, a method for a server to detect geological structures, stratum morphological changes, and abnormal areas ahead of a working face based on full-space wavefield data includes: Step S1: Pre-process the vibration data from the detector and the vibration data from the demodulator to obtain high-quality data.

[0051] During the preprocessing process, the preprocessing method specifically includes: Based on the noise signals recorded when the mining machinery is not in motion but other equipment in the tunnel is in motion, adaptive filtering and denoising are performed on the vibration data collected during the mining machinery's cutting process. This method selects vibration data with a high signal-to-noise ratio from the mining machinery's source. Other equipment includes crushers and belt conveyors. This method improves the signal-to-noise ratio of the vibration data generated by the mining machinery's cutting process.

[0052] The vibration data from the demodulator is spatially integrated to obtain vibration data of the demodulator with a high signal-to-noise ratio. In this way, the signal-to-noise ratio of the vibration data of the demodulator is improved.

[0053] Combining the vibration data and precise positioning of the mining machinery source, coherent deconvolution, Wiener filtering, fk filtering and adaptive gain control are performed based on similarity signals to extract reflected seismic wavelets from high-quality data or target data.

[0054] Step S2: High-resolution imaging technology and full waveform inversion technology (such as Kirchhof migration and reverse time migration) are used to process high-quality data or target data to obtain imaging results of the geological structure and wave velocity anomaly areas in front of the mining working face. The target data is the data obtained by pre-processing the vibration data from the demodulator.

[0055] Leveraging the unique environment of simultaneous mining and excavation detection, the high data density and wide bandwidth of distributed fiber-optic acoustic sensing, and the advantages of full-space wavefield information acquisition within the tunnel, high-resolution imaging is achieved. While using only target data can provide images of the geological structure and wave velocity anomalies ahead of the mining face, using high-quality data yields even more accurate and higher-resolution images.

[0056] Step S3: Diffraction wave imaging (based on "full wavefield" information, including diffraction and scattered waves) is used to process high-quality data or target data to obtain images of smaller-scale geological structures and anomalies ahead of the mining face. It should be noted that diffraction wave imaging can image smaller-scale anomalies, making it a "super-resolution" imaging method. For example, the imaging method used in step S2 is generally effective for detecting faults greater than half the coal thickness. However, diffraction wave imaging can exceed this resolution, making it more conducive to analyzing smaller-scale geological structures and anomalies ahead of the mining face.

[0057] Step S4: Based on the dispersion inversion algorithm of passive source background noise, the characteristics of distributed optical fiber high-density acquisition are utilized, and the frequency Bessel transform method is adopted to extract the dispersion curves of fundamental and high-order surface waves from high-quality data or target data. Then, the surface wave dispersion analysis method is used for inversion to obtain information on the abnormal phase velocity areas in the surrounding rock in front of the mining working face and on both sides of the tunnel.

[0058] Step S5: Based on the imaging results, artificial intelligence methods are used to analyze and identify the structures of faults, folds, fracture zones, collapse columns, voids, igneous rocks, coal-rock interfaces, and roadway roof and floor undulations.

[0059] Step S6: Combining the high-density, long-term continuous acquisition characteristics of distributed optical fiber seismic signals, the passive source method is used to process high-quality data or target data, and inversion is performed to obtain the time-varying data of the physical parameters at different locations within the tunnel structure and the mining working face. The physical parameters include: wave velocity, resonance frequency, elastic modulus, and attenuation coefficient (quality factor).

[0060] Step S7: Using the target data, monitor the wave velocity variation data and microseismic data of the rock mass around the roadway or the coal body (ore body) to be mined over time, analyze the changes in the physical properties of the roadway surrounding rock or the coal body (ore body) to be mined at different time scales, infer the corresponding stress changes generated by the mining process, combine microseismic monitoring and positioning, infer the development of new fractures generated by the mining process, and integrate various types of monitoring data to analyze, investigate, and predict hidden geological disaster factors in the mining process.

[0061] The so-called microseismic refers to the tiny vibrations caused by the stress and structure of the coal mine rock strata. The laid optical cables can be used to collect microseismic data, as well as to achieve microseismic monitoring and positioning.

[0062] In summary, the distributed fiber-optic acoustic sensing-based, in-process seismic advance detection system of the present invention comprises: a detector, an optical cable, a demodulator, and a server. During the production process, the detector collects vibration data from the mining machinery and transmits it to the server via the network; the optical cable is tightly coupled to the tunnel wall of the working face, sensing the vibration of the mining machinery's seismic source at equally spaced points; the demodulator measures the vibration of the equally spaced measurement points on the optical cable and returns the measurement data packets to the demodulator; the demodulator demodulates the vibration waveform data and uploads it to the server; the server receives the full-space wavefield data in real time and, based on the full-space wavefield data, detects the geological structure, stratigraphic morphological changes, and abnormal areas ahead of the working face.

[0063] This invention addresses the shortcomings of various traditional geophysical exploration methods, particularly the problems with the regular application of cable-type seismometers for on-the-go seismic detection. It creatively introduces a distributed fiber-optic acoustic sensing system into an integrated on-the-go seismic detection and monitoring system. Based on distributed fiber-optic acoustic sensing technology, it utilizes the vibrations generated by mining machinery cutting coal and rock layers to achieve on-the-go seismic detection at the working face. This system has the following advantages: (1) The entire system utilizes the emerging cutting-edge distributed fiber acoustic sensing (DAS) technology and optical cables arranged close to the coal wall. It can collect full wavefield information of the mine space at a high density of N meters (for example, 0.5 meters, 1 meter), which helps to separate various seismic phases and diffraction waves and scattered wave fields, and improve the resolution of advance detection during mining for different advance detection targets.

[0064] (2) The entire system uses the vibration signals generated by the coal mining machine and the tunnel boring machine when cutting coal and rock as the seismic source, and places detectors on the coal mining machine and the tunnel boring machine to record the seismic source signals in real time, which can provide accurate seismic source information for the coherent deconvolution of the wave field, so as to improve the pulse effect of the seismic source during mining and tunneling, and thus improve the resolution of advanced detection.

[0065] (3) After the entire system is laid out, there is no need to move the distributed optical cable, making maintenance simple for underground workers.

[0066] (4) The equipment used in the entire system is powered by normal power supply and does not need to be charged in the well or can last for several days on a single charge, ensuring the normal operation of the system.

[0067] (5) If a seismic detection system is constructed while excavating and optical cables are pre-buried, the pre-buried optical cables can be reused at the working face to directly form a seismic detection system while mining, without the need for repeated construction. In addition, the pre-buried optical cables can also provide seismic detector functions for channel wave detection before mining at the working face, further saving geophysical exploration costs.

[0068] (6) The pre-buried optical cable can also naturally enter the goaf as the mining process progresses, forming a goaf monitoring system, providing an effective tool for goaf microseismic monitoring, water accumulation monitoring, and goaf stress monitoring.

[0069] (7) By making full use of the advantages of real-time and high-density data collection, it is possible to monitor the changes in geological structures and geological properties over time during the mining process with high sensitivity, and timely discover hidden disaster-causing factors such as stress concentration, crack development, and water channels caused by the mining process. The hidden disaster-causing factors can be checked and warned through the artificial intelligence system.

[0070] (8) Compared with the existing advance detection method based on traditional seismic detectors during mining and excavation, the method adopted by the system proposed in the present invention increases the spatial density of seismic data acquisition, improves the real-time and continuity of acquisition, and reduces the cost of data acquisition and instrument maintenance; it combines high-density continuous seismic acquisition with full-wavefield seismic imaging methods to improve the resolution, accuracy and real-time performance of detection during mining and excavation.

[0071] (9) Compared with artificial source seismic detection methods such as slot waves, TSP, and TRT, the method adopted by the system proposed in the present invention has high data acquisition density, continuous time, and high imaging resolution; it does not require explosive sources or manual hammering, which improves safety and reduces construction costs; it does not affect the normal progress of mining work and can be detected simultaneously during the mining process; it can continuously monitor geological structure changes and wave velocity anomalies caused by the mining process.

[0072] (10) Compared with underground transient electromagnetic, pit penetration, geological radar and other electromagnetic methods, the method adopted by the system proposed in the present invention is not subject to interference from underground metal equipment, has a long detection distance, and is more sensitive to geological structures.

[0073] The in-mining and excavation seismic advance detection system based on distributed fiber optic acoustic sensing proposed in the present invention is a new type of in-mining and excavation seismic detection system. The system and its detection method solve the problems existing in traditional technologies, provide real-time and continuous perception and monitoring capabilities of small-scale geological structures, and are widely used in various mining and excavation projects such as mines, water conservancy, and transportation. It promotes the development of intelligent coal mining, intelligent excavation, and safety monitoring of mines and excavation projects, and has high practicality.

[0074] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0075] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0076] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A mining-as-you-go seismic advance detection system based on distributed fiber optic acoustic sensing, characterized in that: include: Detector, optical cable, demodulator, server; The geophone is mounted on a mining machine and is used to collect vibration data of a mining machine seismic source and transmit it to the server, wherein the mining machine seismic source is vibration generated when the mining machine cuts a coal layer. The mining machine includes: a shearer at a coal mining face or a tunneling machine or a tunneling anchoring machine at a tunneling face; The optical cable is tightly coupled to the tunnel wall of the working face and is used to sense the vibration of the mining machinery source at equally spaced points; The demodulator is connected to the optical cable and is used to measure the vibration sensed by the optical cable to obtain measurement data, demodulate the measurement data to obtain corresponding vibration data, and then transmit it to the server; The server is used to receive full-space wavefield data in real time and detect geological structures, stratum morphological changes and abnormal areas in front of the working face based on the full-space wavefield data. The full-space wavefield data includes vibration data from the detector and vibration data from the demodulator.

2. The mining and excavation seismic advance detection system according to claim 1 is characterized in that: The detector is a vibration detector in various forms.

3. The mining and excavation seismic advance detection system according to claim 1 is characterized in that: In the coal mining working face, the detector is installed inside the shearer drum or at the position of the front and rear rocker arms of the shearer close to the drum; The geophone collects vibration data of the shearer's seismic source and transmits the data to the server via the network; The detector is connected to the power supply of the coal mining machine and has a built-in battery.

4. The mining and excavation seismic advance detection system according to claim 1, characterized in that: At the excavation working face, the detector is installed at a position close to the blasting head of the excavator; The geophone collects vibration data of the tunnel boring machine's earthquake source and transmits the data to the server via the network; The detector is connected to the power supply of the tunnel boring machine and has a built-in battery.

5. The mining and excavation seismic advance detection system according to claim 1 is characterized in that: In the coal mining working face, the optical cable is laid on the roadway walls of the drift and the lower drift on the coal mining working face and is tightly coupled with the roadway walls; The optical cable is pre-buried and laid together with the support construction during tunnel excavation when the working face is excavated up and down the trench, or is pre-buried and laid uniformly before the coal mining working face is mined; The optical cable is connected to a dedicated fiber core of the mine industrial ring network at the working face exit, or the optical cable is connected to a switch of the mine industrial ring network through a dedicated demodulator-switch integrated machine at the working face exit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face; After the optical cable is laid, as the coal mining process progresses, the optical cable near the working face is cut, and a knot or optical extinction operation is performed at the break point of the optical cable to reduce noise at the broken end; After the optical cable is laid, as the coal mining process progresses, the optical cable on the tunnel wall away from the working face naturally extends into the goaf to monitor the goaf.

6. The mining and excavation seismic advance detection system according to claim 1, characterized in that: At the excavation working face, the optical cables are laid on both sides of the excavation tunnel, tightly coupled with the tunnel sides, and well marked; During the construction of support for excavation of the working face, the optical cables on both sides of the excavation tunnel are pre-buried and laid together. If there are special circumstances, the optical cables on only one side of the tunnel are laid. In the case of laying the optical cables on only one side of the tunnel, the tunnel side close to the coal mining working face is preferred; The optical cable is connected to the dedicated fiber core of the mine industrial ring network at the working face exit, or the optical cable is connected to the switch of the mine industrial ring network through a dedicated demodulator-switch integrated machine at the working face exit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face.

7. The mining and excavation seismic advance detection system according to claim 1 is characterized in that: The process of the demodulator measuring the vibration sensed by the optical cable to obtain measurement data includes: The demodulator emits a pulsed laser and transmits it to the optical cable through an industrial ring network or an independent fiber core. The vibration of the corresponding equally spaced points of the optical cable is measured using the Rayleigh scattering effect, and the measured Rayleigh scattering signal is returned to the demodulator through the industrial ring network or the independent fiber core. The demodulator demodulates the vibration waveform data and transmits it to the server.

8. The mining-as-you-dig seismic advance detection system according to any one of claims 1, 5 or 6, characterized in that: During the laying process of the optical cable, different fixing methods are selected according to different internal support forms of the tunnel. The fixing methods include: first fixing the optical cable on the tunnel wall using a first fixing method, laying an anchor net, and then bonding the optical cable to the tunnel wall using cement spraying. The first fixing method includes: dense clips; or It is laid inside the anchor net using a second fixing method, in direct contact with the tunnel wall. The second fixing method includes: gypsum fixing, spraying fixing, and polymer material fixing; The optical cable should be laid straight, tight and parallel to the tunnel floor.

9. The mining-as-you-dig seismic advance detection system according to any one of claims 1, 5 or 6, characterized in that: The parameters that need to be recorded during the optical cable laying process include: The relationship between the length of the optical cable and the absolute coordinates of the roadway; The extension length of each optical cable from the demodulator and its corresponding relationship with the coordinates of the center line of the roadway; The height of each optical cable relative to the tunnel floor; The types of tunnels in which the optical cables are installed include: heading tunnels and coal mining tunnels.

10. The mining and excavation seismic advance detection system according to claim 1, characterized in that: The method for the server to detect geological structures, stratum morphological changes and abnormal areas in front of the working face based on the full-space wave field data includes: Preprocessing the vibration data from the detector and the vibration data from the demodulator to obtain high-quality data; High-resolution imaging technology and full waveform inversion technology are used to process high-quality data or target data to obtain imaging results of the geological structure and wave velocity anomaly areas in front of the mining working face. The target data is the data obtained by pre-processing the vibration data from the demodulator; Processing the high-quality data or the target data using a diffraction wave imaging method to obtain imaging results of the geological structure and abnormal body conditions in front of the mining working face; Based on the dispersion inversion algorithm of passive source background noise, the characteristics of distributed optical fiber high-density acquisition are utilized, and the frequency Bessel transform method is adopted to extract the dispersion curves of fundamental and high-order surface waves from the high-quality data or the target data. Then, the surface wave dispersion analysis method is used for inversion to obtain information on the abnormal phase velocity areas in the surrounding rock in front of the mining working face and on both sides of the roadway; Based on the imaging results, artificial intelligence methods are used to analyze and identify the structures of faults, folds, fracture zones, collapse columns, voids, igneous rocks, coal-rock interfaces, and roadway roof and floor undulations; Processing the high-quality data or the target data using a passive source method to invert and obtain temporal variation data of physical parameters of the tunnel structure and different locations within the mining working face, the physical parameters including wave velocity, resonance frequency, elastic modulus, and attenuation coefficient; Utilizing the target data, monitoring the wave velocity variation data and microseismic data of the rock mass surrounding the roadway or the coal body to be mined over time, analyzing the changes in the physical properties of the roadway surrounding rock or the coal body to be mined at different time scales, inferring the corresponding stress changes generated by the mining process, combining microseismic monitoring and positioning to infer the development of new fractures generated by the mining process, and integrating various monitoring data to analyze, investigate, and predict hidden geological disaster factors in the mining process; The pre-processing specifically includes: Based on the noise signals recorded when the mining machinery is not in motion but other equipment in the tunnel is in motion, the vibration data collected during the cutting of the mining machinery is adaptively filtered and denoised to obtain the vibration data of the mining machinery source with a high signal-to-noise ratio. The other equipment includes: crushers and belt conveyors; Performing spatial integration on the vibration data from the demodulator to obtain vibration data of the demodulator with a high signal-to-noise ratio; Combining the vibration data and precise positioning of the mining machinery source, coherent deconvolution, Wiener filtering, fk filtering and adaptive gain control are performed based on similarity signals to extract reflected seismic wavelets from the high-quality data or the target data.

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