Distributed fiber optic acoustic sensing based seismic advance detection system with simultaneous excavation and acquisition

Abstract

The application discloses a distributed optical fiber acoustic sensing based seismic advanced detection system with mining. It is related to the technical field of seismic exploration. Based on the distributed optical fiber acoustic sensing technology, the vibration generated by the cutting of coal rock stratum by mining machinery is utilized to realize the seismic detection with mining. In the production process, the detector collects the vibration data of the mining machinery and transmits the data to the server through a network; the optical cable is arranged on the two sides of the upper and lower crossheading of the coal mining face or the two sides of the roadway of the tunneling face; the demodulator sends out pulsed laser and transmits the laser to the optical cable of the working face through an industrial ring network or an independent fiber core, measures the vibration of the vibration points of the optical cable at equal intervals, and returns the measured data packet to the demodulator through the industrial ring network or the independent fiber core; after the demodulator demodulates the vibration waveform data, the demodulator is uploaded to the server; after the waveform is denoised by the server data processing software, the waveform is stored, imaged and intelligently interpreted in real time, so that the geological structure and the abnormal area in front of the working face are detected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seismic exploration, in particular to a seismic advanced detection system based on distributed optical fiber acoustic sensing and used in mining and tunneling. BACKGROUND

[0002] With the deep exploration and development of underground mineral resources, and the actual needs of energy, transportation, water conservancy, military and other projects, underground mining and tunneling projects have developed on a large scale, and the frequency of crossing high-risk geological areas such as fault zones, water-rich areas and stress change areas is increasing. With the advancement of mining and tunneling projects, it is necessary to accurately and efficiently perceive the geological structure and spatial changes in front of the working face, dynamically build a high-precision transparent geological model, guide the adaptive operation of mining equipment, and realize intelligent mining with few or no people in the underground working face.

[0003] At present, the geophysical methods for underground mining and tunneling working faces include electromagnetic methods and seismic methods. The electromagnetic methods mainly include underground transient electromagnetic method, direct current method, geological radar and wireless electromagnetic wave perspective. The seismic methods include channel wave seismic exploration, TSP, TRT and seismic detection with mining and tunneling. These methods mainly have the following limitations:

[0004] (1) Electromagnetic methods: Transient electromagnetic method and direct current method are sensitive to low-resistance water-rich areas, while geological radar and wireless electromagnetic wave perspective are sensitive to geological structures with different electrical properties. However, these electromagnetic methods will be strongly disturbed by underground metal mechanical equipment and anchor net support, resulting in large errors.

[0005] (2) Seismic methods: Channel wave seismic exploration and TSP method generally use explosive sources, which have strong energy and long detection distance, but the operation of underground explosive construction is complex, the safety is poor, and the roadway support is damaged to a certain extent. TRT method uses hammering source, which avoids the shortcomings of explosive source, but the quality is difficult to guarantee due to large workload of manual hammering, and the hammering energy is small, resulting in small detection distance. More importantly, these methods need to be carried out when coal mining or tunneling stops, which affects production, has high data acquisition cost and cannot realize continuous monitoring. Seismic detection with mining and tunneling uses the vibration generated by mining and tunneling machinery cutting as a source, which avoids the weaknesses of unsafe explosive source and small energy of hammering source, and has little disturbance to mining and tunneling work. However, the current method mainly uses traditional cable seismic instrument for data acquisition, which has the following problems in normal application:

[0006] 1) The construction and maintenance are complex, the instrument cost is high, it is difficult to realize high-density seismic acquisition, the complete working face spatial wave field information cannot be obtained, the high-resolution full-wave field imaging method cannot be used, and the resolution of seismic detection with mining and tunneling is affected.

[0007] 2) The measured seismic data is discontinuous and has poor real-time performance.

[0008] 3) With the tunnel excavation or working face mining, the geophone is far away from the seismic source or is destroyed by the mining process, and the geophone array needs to be manually moved in a cycle, which further increases the detection cost and cannot realize real-time monitoring of the changing geological conditions during mining. SUMMARY

[0009] In view of the above problems, the present application provides a mining and tunneling seismic advanced detection system based on distributed optical fiber acoustic sensing.

[0010] The embodiment of the present application provides a mining and tunneling seismic advanced detection system based on distributed optical fiber acoustic sensing, comprising: a geophone, an optical cable, a demodulator, and a server.

[0011] The geophone is installed on the mining machine and is used to collect vibration data of the mining machine seismic source and transmit the vibration data to the server, wherein the mining machine seismic source is the vibration generated when the mining machine cuts the coal rock stratum, and the mining machine includes a coal mining machine on a coal mining face or a tunneling machine or a tunneling and anchoring integrated machine on a tunneling face.

[0012] The optical cable is tightly coupled with the roadway side of the working face and is used to sense the vibration of the mining machine seismic source at equidistant points.

[0013] The demodulator is connected with 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 transmit the vibration data to the server.

[0014] The server is used to receive full-space wave field data in real time, and based on the full-space wave field data, to detect the geological structure, stratum morphology change and abnormal area in front of the working face, wherein the full-space wave field data includes vibration data from the geophone and vibration data from the demodulator.

[0015] Optionally, the geophone is a vibration geophone in multiple forms.

[0016] Optionally, in the coal mining face, the geophone is installed inside the drum of the coal mining machine or at a position close to the drum of the front and rear swing arms of the coal mining machine.

[0017] The geophone collects vibration data of the coal mining machine seismic source and transmits the vibration data to the server through a network.

[0018] The geophone is connected to the power supply of the coal mining machine and has a built-in battery.

[0019] Optionally, in the tunneling face, the geophone is installed at a position close to the drill head of the tunneling machine.

[0020] The detector collects vibration data of the tunneling machine vibration source and transmits the data to the server through a network.

[0021] The detector accesses the power supply of the tunneling machine and is provided with a built-in battery.

[0022] Optionally, in the coal mining face, the optical cable is laid on the roadway sides of the crossheading and the tailgate and is tightly coupled with the roadway sides.

[0023] The optical cable is pre-embedded and laid along with the support construction of the roadway during the excavation of the crossheading and the tailgate of the coal mining face, or is uniformly pre-embedded before the mining of the coal mining face.

[0024] The optical cable is connected with the special fiber core of the mine industrial ring network at the exit of the coal mining face, or the optical cable is connected with the switch of the mine industrial ring network through a special demodulation and exchange integrated machine at the exit of the coal mining face, and the signal is led out to the demodulation machine to form a distributed optical cable measurement system surrounding the coal mining face.

[0025] After the optical cable is laid, with the advancement of the coal mining process, the optical cable near the side of the coal mining face is cut off, and knotting or light extinction is performed at the breakpoint of the optical cable to reduce the noise of the broken end.

[0026] After the optical cable is laid, with the advancement of the coal mining process, the optical cable on the roadway sides away from the coal mining face naturally extends into the goaf for monitoring the goaf.

[0027] Optionally, in the tunneling face, the optical cable is laid on the two sides of the tunneling roadway and is tightly coupled with the roadway sides and is well marked.

[0028] During the support construction of the coal mining face, the optical cable on the two sides of the tunneling roadway is pre-embedded and laid, and if it is limited by special circumstances, only the optical cable on one side of the roadway is laid, and in the case of laying the optical cable on one side of the roadway, the side of the roadway near the coal mining face is preferred.

[0029] The optical cable is connected with the special fiber core of the mine industrial ring network at the exit of the coal mining face, or the optical cable is connected with the switch of the mine industrial ring network through a special demodulation and exchange integrated machine at the exit of the coal mining face, and the signal is led out to the demodulation machine to form a distributed optical cable measurement system surrounding the coal mining face.

[0030] Optionally, the process of measuring the vibration sensed by the optical cable by the demodulation machine to obtain measurement data includes:

[0031] The demodulation machine emits pulsed laser and transmits to the optical cable through the industrial ring network or independent fiber core, measures the vibration of the corresponding equally spaced points of the optical cable by Rayleigh scattering effect, and returns the measured Rayleigh scattering signal to the demodulation machine through the industrial ring network or independent fiber core, and the demodulation machine demodulates the vibration waveform data and transmits it to the server.

[0032] Optionally, during the laying process of the optical cable, different fixing methods are selected according to different internal support forms of the roadway, the fixing methods include: first fixing the optical cable on the roadway side by using a first fixing method, laying an anchor net, and then bonding the optical cable to the roadway side by using cement injection, the first fixing method includes: dense clips; or,

[0033] Laying in the anchor net inside and directly contacting with the roadway side by using a second fixing method, the second fixing method includes: gypsum fixing, injection fixing, and high polymer material fixing;

[0034] The optical cable laying should be kept straight and tight, and parallel to the roadway floor.

[0035] Optionally, the parameters required to be recorded during the laying process of the optical cable include:

[0036] The relationship between the length of the optical cable and the absolute coordinates of the roadway;

[0037] The extension length value of each optical cable from the demodulation machine, and the corresponding relationship with the center line coordinates of the roadway;

[0038] The height of each optical cable relative to the roadway floor;

[0039] The type of roadway where each optical cable is installed, the type of roadway includes: tunneling roadway and coal mining roadway.

[0040] Optionally, the method for detecting the geological structure, stratum morphology change and abnormal area in front of the working face based on the full-space wave field data of the server includes:

[0041] Pretreating the vibration data from the geophone and the vibration data from the demodulation machine to obtain high-quality data;

[0042] Using high-resolution imaging technology and full-waveform inversion technology to process the high-quality data or target data to obtain imaging results of the geological structure in front of the mining working face and the wave velocity abnormal area, the target data is obtained by pretreating the vibration data from the demodulation machine;

[0043] Using diffraction wave imaging method to process the high-quality data or the target data to obtain imaging results of the geological structure and abnormal body in front of the mining working face;

[0044] The dispersion inversion algorithm based on passive source background noise utilizes the characteristics of high-density acquisition by distributed optical fiber and adopts the frequency Bessel transform method to extract the dispersion curves of the fundamental and higher order surface waves from the high-quality data or the target data. Then, the surface wave dispersion analysis method is used to invert and obtain information on the abnormal phase velocity regions inside the surrounding rock in front of the mining working face and on both sides of the roadway.

[0045] 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 the undulations of the roadway roof and floor.

[0046] The high-quality data or the target data is processed using the passive source method to invert and obtain the changes in physical parameters of the roadway structure and different locations inside the mining face over time. The physical parameters include: wave velocity, resonant frequency, elastic modulus, and attenuation coefficient.

[0047] Using the target data, monitor the wave velocity variation data and microseismic data of the surrounding rock mass or coal body to be mined over time, analyze the changes in physical properties of the surrounding rock mass or coal body to be mined at different time scales, infer the corresponding stress changes generated during the mining process, combine microseismic monitoring and location, infer the development of new fractures generated during the mining process, and comprehensively analyze, investigate and predict hidden geological disaster factors during the mining process by integrating various monitoring data;

[0048] The preprocessing specifically includes:

[0049] Based on the noise signals recorded by other equipment in the roadway when the mining machinery is not in operation, 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 vibration source with high signal-to-noise ratio. The other equipment includes: crusher and belt conveyor.

[0050] Spatial integration is performed on the vibration data from the demodulator to obtain vibration data of the demodulator with a high signal-to-noise ratio.

[0051] By combining the vibration data and precise positioning of the mining machinery seismic source, coherent deconvolution, Wiener filtering, FK filtering, and adaptive gain control are performed based on similarity signals to extract the reflected seismic wavelet from the high-quality data or the target data.

[0052] The present invention relates to a seismic advance detection system for mining operations based on distributed fiber optic acoustic sensing, comprising: a geophone, an optical cable, a demodulator, and a server. During production, the geophone collects vibration data from the mining machinery and transmits it to the server via a network; the optical cable is tightly coupled to the roadway wall of the working face, sensing the vibrations of the mining machinery's seismic sources at equally spaced points; the demodulator measures the vibrations at equally spaced measuring points on the optical cable and returns the measurement data packets to the demodulator; after demodulating the vibration waveform data, the demodulator uploads it to the server; the server receives full-space wavefield data in real time and, based on the full-space wavefield data, detects geological structures, stratigraphic changes, and anomalous areas ahead of the working face.

[0053] This invention addresses the shortcomings of traditional geophysical exploration methods, particularly the problems associated with the routine application of cable-stayed seismic instruments for on-demand seismic detection. It creatively introduces a distributed fiber optic acoustic sensing system into an integrated on-demand 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 strata to achieve on-demand seismic detection at the working face. It offers the following advantages:

[0054] (1) The whole system utilizes the emerging and cutting-edge distributed optical fiber acoustic sensing (DAS) technology. By using optical cables arranged close to the coal wall, it can collect the full wave field information of the tunnel space at a high density of N meters (e.g., 0.5 meters, 1 meter). This helps to separate various seismic phases and diffraction and scattering wave fields, and improve the resolution of advance detection during mining and excavation for different advance detection targets.

[0055] (2) The whole system uses the vibration signal generated by the coal mining machine and tunneling machine cutting coal and rock as the source, and places a detector on the coal mining machine and tunneling machine to record the source signal in real time. This can provide accurate source information for the coherent deconvolution of the wave field, so as to improve the pulsed effect of the source during mining and tunneling and thus improve the advanced detection resolution.

[0056] (3) After the entire system is deployed, there is no need to move the location of the distributed optical cable, and the maintenance by the underground staff is simple.

[0057] (4) All equipment used in the system is powered by a normal power supply, and there is no need to charge it at the well or it can last for several days on a single charge, which ensures the normal operation of the system.

[0058] (5) If a seismic detection system is constructed during excavation 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 during mining, without the need for repeated construction. Furthermore, the pre-buried optical cables can also provide the function of a seismic detector for trench wave detection before mining at the working face, further saving geophysical exploration costs.

[0059] (6) The pre-buried optical cable can also naturally enter the goaf area as the mining process progresses, forming a goaf monitoring system. It provides an effective tool for goaf microseismic monitoring, water accumulation monitoring and goaf stress monitoring.

[0060] (7) By making full use of the advantages of real-time and high-density acquisition, it is possible to monitor the changes in geological structure and geological properties over time as the mining process changes, and promptly discover hidden disaster-causing factors such as stress concentration, fissure development, and water-conducting channels brought about by the mining process. The hidden disaster-causing factors can be investigated and warned through artificial intelligence systems.

[0061] (8) Compared with the existing advanced detection method based on traditional seismic detectors, the method adopted by the system proposed in this invention improves the spatial density of seismic data acquisition, improves the real-time and continuous nature of acquisition, and reduces the cost of data acquisition and instrument maintenance; by combining high-density continuous seismic acquisition with full-wavelength seismic imaging method, the resolution, accuracy and real-time nature of the detection method are improved.

[0062] (9) Compared with artificial seismic source seismic detection methods such as channel wave, TSP, and TRT, the system proposed in this invention has high data acquisition density, continuous time, and high imaging resolution; it does not require explosive seismic sources or manual hammering, thus improving safety and reducing 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 structural changes and wave velocity anomalies caused by the mining process.

[0063] (10) Compared with electromagnetic methods such as downhole transient electromagnetic, pit penetration, and ground-penetrating radar, the method used in the system proposed in this invention is not affected by downhole metal equipment, has a long detection range, and is more sensitive to geological structures. Attached Figure Description

[0064] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0065] Figure 1 This is a schematic diagram of an exemplary detector installed on a coal mining machine according to an embodiment of the present invention;

[0066] Figure 2 This is a schematic diagram illustrating the layout of an exemplary coal mining face and tunneling face for deploying a seismic advance detection system for mining and tunneling, according to an embodiment of the present invention.

[0067] Figure 3This is a schematic diagram illustrating the layout of an exemplary seismic advance detection system for a coal mining face in an embodiment of the present invention.

[0068] Figure 4 This is a schematic diagram illustrating the layout of an exemplary seismic advance detection system for tunneling faces in an embodiment of the present invention. Detailed Implementation

[0069] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, 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 merely illustrative of the present invention, and are only some, not all, embodiments of the present invention, and are not intended to limit the present invention.

[0070] This invention proposes a seismic advance detection system based on distributed fiber optic acoustic sensing for mining and tunneling, comprising: a geophone, an optical cable, a demodulator, and a server. The geophone is installed on the mining machinery to collect vibration data from the machinery's vibration source and transmit it to the server. The vibration source is the vibration generated when the mining machinery cuts through coal and rock strata. The mining machinery includes: a coal mining machine in a coal mining face, a tunneling machine in a tunneling face, or a roadheader.

[0071] The optical fiber cable is tightly coupled to the roadway walls of the working face to sense the vibrations of the mining machinery's seismic sources at equally spaced points. Since the optical fiber cable needs to be laid across the entire roadway wall, it is distributed. This distributed cable, tightly coupled to the roadway walls of the working face, ensures the reliability and stability of the collected vibration signals. From the installation perspective, the geophone collects vibration data at the seismic source, while the vibration sensed by the optical fiber cable can be considered as the vibration of the coal and rock strata caused by the seismic source. If the mining machinery's seismic source is considered as an earthquake epicenter, then the geophone collects data from the epicenter, while the optical fiber cable collects data on the seismic waves emanating from the epicenter.

[0072] The demodulator is connected to the optical cable to measure the vibration sensed by the optical cable and obtain measurement data. After demodulating the measurement data to obtain the corresponding vibration data, it is transmitted to the server. The server is used to receive full-space wavefield data in real time and to detect geological structures, stratigraphic 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.

[0073] In one embodiment of the invention, the detector is a vibration detector of various forms. Preferably, a moving coil or MEMS type vibration detector can be selected. Of course, other types of vibration detectors are also applicable, as long as they can be installed on mining machinery.

[0074] In coal mining, there are generally two working faces: the coal face and the tunneling face. The installation locations of geophones and optical cables differ slightly between these two working faces. In the coal face, the geophone is installed inside the coal mining machine drum or near the drum on the front or rear rocker arms. The geophone collects vibration data from the coal mining machine's vibration source and transmits it to a server via a network; the geophone is connected to the coal mining machine's power supply and also has a built-in battery.

[0075] For example: refer to Figure 1 The diagram shows an exemplary installation of a detector on a coal mining machine, which typically has a front drum and a rear drum. Figure 1 The diagram shows geophones installed inside two drums: a front drum geophone and a rear drum geophone. Both geophones are connected to a data acquisition base station via data cables for vibration data exchange. The data acquisition base station then transmits the data to a ground server via the network. The geophones are connected to the coal mining machine's power supply and also have built-in batteries, providing dual backup of both constant power and built-in battery power. Considering the actual site conditions, if the geophones cannot be installed inside the drums, they must be installed on the rocker arm near the drums or on the coal mining machine body. The principle is that the closer to the drum, the more accurate the vibration data collected.

[0076] Similarly, at the tunneling face, geophones are installed on the tunneling machine near the blast head. The geophones collect vibration data from the tunneling machine's vibration source and transmit it to a server via a network. The geophones are connected to the tunneling machine's power supply and also have built-in batteries. Considering the actual site conditions, the geophones on the tunneling machine can be installed in convenient locations, but it should be noted that the closer they are to the blast head, the more accurate the vibration data will be.

[0077] At the coal mining face, the optical cable is laid on the sidewalls of the upper and lower roadways of the coal mining face and is tightly coupled with the roadway sidewalls; the optical cable is pre-buried and laid together with the support construction during the roadway excavation when the upper and lower roadways of the working face are excavated, or it is pre-buried and laid uniformly before the coal mining face is mined.

[0078] The optical cable is connected to the dedicated fiber core of the mine's industrial ring network at the working face exit, or the optical cable is connected to the switch of the mine's industrial ring network through a dedicated demodulation and switching unit at the working face exit, exporting the signal to the demodulator to form a distributed optical cable measurement system surrounding the working face; after the optical cable is laid, as the coal mining process progresses, the optical cable on the side closest to the working face is cut, and knotting or light-extinguishing operations are performed at the optical cable break point to reduce noise at the break end; after the optical cable is laid, as the coal mining process progresses, the optical cable on the roadway side away from the working face naturally extends into the goaf area for goaf monitoring.

[0079] Whether in coal mining or tunneling faces, different fixing methods are selected during the laying of optical cables depending on the internal support structure of the roadway. These methods include: firstly, using a primary fixing method to secure the optical cable to the roadway wall by laying an anchor mesh, and then using cement spraying to bond the optical cable to the roadway wall. The primary fixing method includes dense clamps or similar clamp-like structures to secure the optical cable to the roadway wall. If cement spraying is not feasible, a secondary fixing method is used, where the cable is laid inside the anchor mesh, directly contacting the roadway wall. The secondary fixing method includes plaster fixing, spraying fixing, polymer material fixing, and other similar methods. The optical cable should be laid straight and taut, parallel to the roadway floor.

[0080] Both the demodulator and the server can be deployed in a ground-based data center. To ensure the system operates without maintenance, both the demodulator and the server use a dual backup mode of constant power supply and built-in battery power supply.

[0081] To better understand the aforementioned seismic advance detection system deployed in coal mining faces during mining operations, refer to... Figure 2 The diagram shows an exemplary layout of a seismic advance detection system for coal mining and tunneling faces. Figure 2 The diagram to the left of the black vertical line shows the layout of the seismic advance detection system for coal mining faces; the diagram to the right of the black vertical line shows the layout of the seismic advance detection system for tunneling faces. For clarity, the following diagrams illustrate this further. Figure 3 and Figure 4 As shown.

[0082] Reference Figure 3 The diagram shows an exemplary layout of a seismic advance detection system for mining operations at a coal face. Figure 3 In the mining area, fiber optic cables are laid close to the face of the cut in the roadway and tightly coupled to the coal face. In the cut, fiber optic cables are laid deep into the goaf. The goaf monitoring system is used to collect and monitor vibration data from the goaf. The accompanying monitoring system collects and monitors vibration data from the mining area. All data is sent to a demodulator on the ground, processed, and then transmitted to a server for further processing.

[0083] For the tunneling face, the optical cable is laid on both sides of the tunnel, tightly coupled to the tunnel walls, and clearly marked. During the tunneling support construction, the optical cable on both sides of the tunnel is pre-buried. If there are special restrictions, such as one side of the tunnel wall being unable to be laid with optical cable, then only one side of the tunnel wall is laid. In the case of laying only one side of the tunnel wall, priority is given to laying the side of the tunnel wall closer to the coal mining face, which facilitates reuse for subsequent mining detection. At the working face exit, the optical cable is connected to the dedicated fiber core of the mine's industrial ring network, or, at the working face exit, the optical cable is connected to the switch of the mine's industrial ring network through a dedicated demodulation and switching unit, exporting the signal to the demodulator to form a distributed optical cable measurement system surrounding the working face.

[0084] To better understand the aforementioned seismic advance detection system deployed at the tunneling face during mining operations, refer to... Figure 4 The diagram shows an exemplary layout of a pre-excavation seismic detection system for a tunneling face. Figure 4 The example illustrates a tunneling machine and a detector mounted on it. Straight-coupled optical cables and / or coiled optical cables can be used to tightly couple the optical cables to the sides of the tunnel. At the working face exit, the optical cable connects to a dedicated fiber core of the mine's industrial ring network; alternatively, at the working face exit, the optical cable connects to a switch in the mine's industrial ring network via a dedicated demodulation and switching unit, exporting the signal to a ground demodulator.

[0085] In one embodiment of the present invention, the demodulator serves as the core device for distributed fiber optic acoustic sensing. The process by which the demodulator measures the vibrations sensed by the optical cable to obtain measurement data includes: the demodulator emitting pulsed laser light and transmitting it to the optical cable via an industrial ring network or independent fiber core; utilizing the Rayleigh scattering effect to measure the vibrations at equally spaced points on the optical cable; and returning the measured Rayleigh scattering signals to the demodulator via the industrial ring network or independent fiber core. After demodulating the vibration waveform data, the demodulator uploads it to a server, enabling high-density measurements with intervals as low as 1 meter.

[0086] In addition, the parameters that need to be recorded during the fiber optic cable laying process include: the relationship between the fiber optic cable length and the absolute coordinates of the roadway; the extension length of each fiber optic cable from the demodulator and its correspondence with the coordinates of the roadway centerline; the height of each fiber optic cable relative to the roadway floor; and the type of roadway in which each fiber optic cable is installed, including tunneling roadways and coal mining roadways.

[0087] The workflow of a seismic advance detection system based on distributed fiber optic acoustic sensing during mining can be summarized as follows:

[0088] During production, the detector collects vibration data of the mining machinery and transmits it to the server via the network; the demodulator emits pulsed lasers and transmits them to the optical cable at the working face via an industrial ring network or independent fiber core, measuring the vibration of the optical cable at equally spaced measurement points, and returning the measured Rayleigh scattering signals to the demodulator via the industrial ring network or independent fiber core; after demodulating the vibration waveform data, the demodulator uploads it to the server; the server processes the waveform noise reduction and stores it, and performs real-time intelligent interpretation to realize the detection of geological structures and abnormal areas in front of the working face.

[0089] In one embodiment of the present invention, the server detects geological structures, stratigraphic changes, and anomalous areas ahead of the working face based on full-space wavefield data. Preferably, data processing software can be deployed on the server to receive the transmitted full-wavefield data of the tunnel in real time and perform data denoising, imaging, and geological interpretation using the data processing software. The data processing software stores the waveform after denoising and performs real-time intelligent interpretation to realize the detection of geological structures, stratigraphic changes, and anomalous areas ahead of the working face. In addition, due to the laying of optical cables, it can sense not only the vibrations generated by mining machinery but also the conditions of mine pressure, microseismic activity, and hydrology during the mining process. Therefore, with this help, the server can achieve real-time monitoring and intelligent interpretation of changes in mine pressure, microseismic activity, and hydrology during the mining process.

[0090] In one embodiment of the present invention, a method for a server to detect geological structures, stratigraphic changes, and anomalous areas ahead of a working face based on full-space wavefield data includes:

[0091] Step S1: Preprocess the vibration data from the detector and the vibration data from the demodulator to obtain high-quality data.

[0092] The preprocessing process includes the following specific methods:

[0093] Based on the noise signals recorded by other equipment operating within the roadway while the mining machinery was not in operation, adaptive filtering and denoising were applied to the vibration data collected during the mining machinery's cutting process. This process selected vibration data from sources with high signal-to-noise ratios, including the mining machinery (crusher, belt conveyor, etc.). This method improved the signal-to-noise ratio of the vibration data generated by the mining machinery during cutting.

[0094] Spatial integration is performed on the vibration data from the demodulator to obtain high signal-to-noise ratio (SNR) vibration data from the demodulator. This method improves the SNR of the demodulator's vibration data.

[0095] By combining vibration data and precise positioning of the seismic source of the mining machinery, coherent deconvolution, Wiener filtering, FK filtering and adaptive gain control are performed based on similarity signals to extract the reflected seismic wavelet from high-quality data or target data.

[0096] Step S2: Using high-resolution imaging technology and full waveform inversion technology (e.g., Koschhoff migration, reverse time migration, etc.), high-quality data or target data are processed to obtain the imaging results of the geological structure and wave velocity anomaly areas in front of the mining face. The target data is the data obtained after preprocessing the vibration data from the demodulator.

[0097] Taking advantage of the unique environment of on-demand mining and the high data density and wide bandwidth of distributed fiber optic acoustic sensors, high-resolution imaging is achieved by fully utilizing the advantages of acquiring full-space wavefield information within the tunnel. While target data alone can provide imaging results of the geological structure and wave velocity anomalies ahead of the mining face, using high-quality data results in more accurate and higher-resolution imaging.

[0098] Step S3: Process high-quality or target data using diffraction wave imaging (based on "full-field" information such as diffraction and scattered waves) to obtain imaging results of smaller-scale geological structures and anomalies ahead of the mining face. It should be noted that diffraction wave imaging can image even 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 seam thickness. Diffraction wave imaging can surpass this resolution, making it more suitable for analyzing smaller-scale geological structures and anomalies ahead of the mining face.

[0099] Step S4: Based on the dispersion inversion algorithm of passive source background noise, the algorithm utilizes the characteristics of high-density acquisition by distributed optical fiber and adopts the frequency Bessel transform method to extract the dispersion curves of the fundamental and higher order surface waves from high-quality data or target data. Then, the dispersion analysis method of surface waves is used to invert and obtain information on the abnormal phase velocity regions inside the surrounding rock in front of the mining face and on both sides of the roadway.

[0100] Step S5: Based on the imaging results, use artificial intelligence methods to analyze and identify the structures of faults, folds, fracture zones, collapse columns, voids, igneous rocks, coal-rock interfaces, and the undulations of the roadway roof and floor.

[0101] Step S6: Combining the characteristics of high-density, long-term continuous acquisition of seismic signals by distributed optical fiber, the passive source method is used to process high-quality data or target data, and the changes of physical parameters of different locations inside the tunnel structure and mining face over time are obtained. The physical parameters include: wave velocity, resonant frequency, elastic modulus, and attenuation coefficient (quality factor).

[0102] Step S7: Using target data, monitor the wave velocity variation data and microseismic data of the surrounding rock mass or the coal body (ore body) to be mined over time, analyze the changes in physical properties of the surrounding rock mass or the coal body (ore body) to be mined at different time scales, infer the corresponding stress changes generated during the mining process, combine microseismic monitoring and location, infer the development of new fractures generated during the mining process, and comprehensively analyze, investigate and predict hidden geological disaster factors during the mining process based on various monitoring data.

[0103] Microseismic events refer to the minute vibrations caused by the stress and structure of coal mine rock strata. Microseismic data can be collected, and microseismic monitoring and location can be achieved through the laying of optical cables.

[0104] In summary, the seismic advance detection system for mining operations based on distributed fiber optic acoustic sensing of the present invention includes: a geophone, an optical cable, a demodulator, and a server. During production, the geophone collects vibration data from the mining machinery and transmits it to the server via a network; the optical cable is tightly coupled to the roadway wall of the working face, sensing the vibration of the mining machinery's seismic sources at equally spaced points; the demodulator measures the vibration at equally spaced measurement points on the optical cable and returns the measurement data packets to the demodulator; after demodulating the vibration waveform data, the demodulator uploads it to the server; the server receives full-space wavefield data in real time and, based on the full-space wavefield data, detects geological structures, stratigraphic changes, and anomalous areas ahead of the working face.

[0105] This invention addresses the shortcomings of traditional geophysical exploration methods, particularly the problems associated with the routine application of cable-stayed seismic instruments for on-demand seismic detection. It creatively introduces a distributed fiber optic acoustic sensing system into an integrated on-demand 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 strata to achieve on-demand seismic detection at the working face. It offers the following advantages:

[0106] (1) The whole system utilizes the emerging and cutting-edge distributed optical fiber acoustic sensing (DAS) technology. By using optical cables arranged close to the coal wall, it can collect the full wave field information of the tunnel space at a high density of N meters (e.g., 0.5 meters, 1 meter). This helps to separate various seismic phases and diffraction and scattering wave fields, and improve the resolution of advance detection during mining and excavation for different advance detection targets.

[0107] (2) The whole system uses the vibration signal generated by the coal mining machine and tunneling machine cutting coal and rock as the source, and places a detector on the coal mining machine and tunneling machine to record the source signal in real time. This can provide accurate source information for the coherent deconvolution of the wave field, so as to improve the pulsed effect of the source during mining and tunneling and thus improve the advanced detection resolution.

[0108] (3) After the entire system is deployed, there is no need to move the location of the distributed optical cable, and the maintenance by the underground staff is simple.

[0109] (4) All equipment used in the system is powered by a normal power supply, and there is no need to charge it at the well or it can last for several days on a single charge, which ensures the normal operation of the system.

[0110] (5) If a seismic detection system is constructed during excavation 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 during mining, without the need for repeated construction. Furthermore, the pre-buried optical cables can also provide the function of a seismic detector for trench wave detection before mining at the working face, further saving geophysical exploration costs.

[0111] (6) The pre-buried optical cable can also naturally enter the goaf area as the mining process progresses, forming a goaf monitoring system. It provides an effective tool for goaf microseismic monitoring, water accumulation monitoring and goaf stress monitoring.

[0112] (7) By making full use of the advantages of real-time and high-density acquisition, it is possible to monitor the changes in geological structure and geological properties over time as the mining process changes, and promptly discover hidden disaster-causing factors such as stress concentration, fissure development, and water-conducting channels brought about by the mining process. The hidden disaster-causing factors can be investigated and warned through artificial intelligence systems.

[0113] (8) Compared with the existing advanced detection method based on traditional seismic detectors, the method adopted by the system proposed in this invention improves the spatial density of seismic data acquisition, improves the real-time and continuous nature of acquisition, and reduces the cost of data acquisition and instrument maintenance; by combining high-density continuous seismic acquisition with full-wavelength seismic imaging method, the resolution, accuracy and real-time nature of the detection method are improved.

[0114] (9) Compared with artificial seismic source seismic detection methods such as channel wave, TSP, and TRT, the system proposed in this invention has high data acquisition density, continuous time, and high imaging resolution; it does not require explosive seismic sources or manual hammering, thus improving safety and reducing 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 structural changes and wave velocity anomalies caused by the mining process.

[0115] (10) Compared with electromagnetic methods such as downhole transient electromagnetic, pit penetration, and ground-penetrating radar, the method used in the system proposed in this invention is not affected by downhole metal equipment, has a long detection range, and is more sensitive to geological structures.

[0116] The seismic advance detection system based on distributed fiber optic acoustic sensing proposed in this invention is a novel seismic detection system for mining and tunneling. This system and its detection method solve the problems existing in traditional technologies, providing real-time and continuous perception and monitoring capabilities for small-scale geological structures. It can be widely used in various mining projects such as mining, water conservancy, and transportation, promoting the development of intelligent coal mining, intelligent tunneling, and safety monitoring of mining and tunneling projects, and has high practicality.

[0117] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0118] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0119] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A seismic advance detection system for mining and excavation based on distributed fiber optic acoustic sensing, characterized in that, include: Detectors, optical cables, demodulators, servers; The detector is installed on the mining machinery to collect vibration data of the mining machinery's vibration source and transmit it to the server. The vibration source of the mining machinery is the vibration generated when the mining machinery cuts coal and rock layers. The mining machinery includes: a coal mining machine in a coal mining face or a tunneling machine or a tunneling and anchoring machine in a tunneling face. The optical cable is tightly coupled to the roadway side of the working face and is used to sense the vibration of the mining machinery vibration 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 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 to detect geological structures, stratigraphic changes and anomalous 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. The method for the server to detect geological structures, stratigraphic changes, and anomalous areas ahead of the working face based on the full-space wavefield data includes: The vibration data from the detector and the demodulator are preprocessed to obtain high-quality data. High-resolution imaging and full-waveform inversion techniques are then used to process the high-quality data or target data to obtain imaging results of the geological structure and wave velocity anomaly areas ahead of the mining face. The target data is obtained after preprocessing the vibration data from the demodulator. Diffraction wave imaging is then used to process the high-quality data or target data to obtain imaging results of the geological structure and anomalies ahead of the mining face. Based on a passive source background noise dispersion inversion algorithm, utilizing the characteristics of distributed fiber optic high-density acquisition, the frequency Bessel transform method is used to extract the dispersion curves of the fundamental and higher-order surface waves from the high-quality data or target data. Then, surface wave dispersion analysis is used to invert the phase velocity within the surrounding rock ahead of the mining face and on both sides of the roadway. Information on anomalous areas; based on imaging results, using artificial intelligence methods, analyze and identify the structures of faults, folds, fracture zones, collapse columns, voids, igneous rocks, coal-rock interfaces, and the undulations of the roadway roof and floor; using passive source methods to process the high-quality data or the target data, invert the changes in physical parameters of the roadway structure and different locations inside the mining face over time, including wave velocity, resonance frequency, elastic modulus, and attenuation coefficient; using the target data, monitor the changes in wave velocity and microseismic data of the surrounding rock mass or the coal body to be mined over time, analyze the changes in physical properties of the surrounding rock or the coal body to be mined at different time scales, infer the corresponding stress changes generated during the mining process, combine microseismic monitoring and location, infer the development of new fractures generated during the mining process, and comprehensively analyze, investigate, and predict hidden geological disaster factors during the mining process based on various monitoring data; The preprocessing specifically includes: Based on the noise signals recorded by other equipment in the roadway when the mining machinery is not in operation, the vibration data collected during the cutting of the mining machinery is adaptively filtered and denoised to obtain vibration data of the mining machinery vibration source with high signal-to-noise ratio. The other equipment includes: crusher and belt conveyor. The vibration data from the demodulator is spatially integrated to obtain vibration data of the demodulator with high signal-to-noise ratio.

2. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, The detector is a vibration detector of various types.

3. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, In the coal mining face, the detector is installed inside the coal mining machine drum or near the drum on the front and rear rocker arms of the coal mining machine; The detector collects vibration data from the coal mining machine's vibration source and transmits it to the server via a network; The detector is connected to the power supply of the coal mining machine and also has a built-in battery.

4. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, At the tunneling face, the detector is installed on the tunneling machine near the blast head; The detector collects vibration data from the tunneling machine's vibration source and transmits it to the server via a network; The detector is connected to the tunneling machine's power supply and also has a built-in battery.

5. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, In the coal mining face, the optical cable is laid on the sidewalls of the upper and lower roadways of the coal mining face and is tightly coupled to the sidewalls. The optical cable is pre-buried and laid together with the support construction during the excavation of the roadway during the upper and lower roadway excavation of the working face, or it is pre-buried and laid uniformly before the coal mining 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 at the working face exit through a dedicated demodulation and switching integrated machine, and the signal is exported to the demodulation machine 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 off, and knotting or light-damping operations are performed at the cut point to reduce noise at the cut end. After the optical cable is laid, as the coal mining process progresses, the optical cable on the side of the roadway away from the working face naturally extends into the goaf to monitor the goaf.

6. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, At the tunneling face, the optical cable is laid on both sides of the tunnel and tightly coupled to the tunnel walls, and is clearly marked. During the excavation and support construction of the working face, the optical cables on both sides of the excavation roadway are pre-buried and laid together. If there are special restrictions, only the optical cable on one side of the roadway is laid. In the case of laying only the optical cable on one side of the roadway, the side of the roadway closer to the excavation working face is preferred. 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 at the working face exit through a dedicated demodulation and switching unit, and the signal is exported to the demodulator to form an optical cable distributed measurement system surrounding the working face.

7. The seismic advance detection system for mining and excavation as described in claim 1, characterized in that, The process by which the demodulator measures the vibration sensed by the optical cable to obtain measurement data includes: The demodulator emits pulsed laser light and transmits it to the optical cable via an industrial ring network or an independent fiber core. It uses the Rayleigh scattering effect to measure the vibration at equally spaced points on the optical cable and returns the measured Rayleigh scattering signal to the demodulator via the industrial ring network or an independent fiber core. The demodulator demodulates the vibration waveform data and transmits it to the server.

8. The seismic advance detection system for mining and excavation as described in any one of claims 1, 5, or 6, characterized in that, During the laying of the optical cable, different fixing methods are selected according to the different support forms inside the tunnel. The fixing methods include: firstly, using a first fixing method to fix the optical cable to the tunnel wall, laying anchor mesh, and then using cement spraying to bond the optical cable to the tunnel wall. The first fixing method includes: dense clamps; or... The second fixing method is used to lay the anchor mesh inside the anchor mesh and to directly contact the tunnel side. The second fixing method includes: plaster fixing, shotcrete fixing, and polymer material fixing. The optical cable should be laid straight and taut, and parallel to the tunnel floor.

9. The seismic advance detection system for mining and excavation as described in any one of claims 1, 5, or 6, characterized in that, The parameters that need to be recorded during the fiber optic cable laying process include: The relationship between the length of the optical cable and the absolute coordinates of the tunnel; The extension length of each optical cable from the demodulator, and its correspondence with the coordinates of the tunnel centerline; The height of each optical cable relative to the tunnel floor; The types of tunnels in which the optical cables are installed include: tunneling tunnels and coal mining tunnels.

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