Tunnel face multichannel transient electromagnetic detection method and device

Abstract

The invention discloses a multi-channel transient electromagnetic detection method and device for a tunnel face, and relates to the technical field of geophysical information, and the method comprises the steps: planning horizontal measuring lines for the tunnel face at equal intervals, and planning measuring points on each measuring line at equal intervals; building a multi-channel detection array composed of a transient electromagnetic receiving coil and a transient electromagnetic transmitting coil, and carrying out primary field zero magnetic flux point adjustment; the method comprises the following steps: setting emission parameters according to detection depth and resolution requirements, then emitting bipolar square waves, carrying out measurement point-by-measurement observation by using an adjusted multi-channel detection array, constructing a geometric network which takes measurement lines, measurement points and channel numbers as indexes according to observation data, and carrying out multi-channel combined three-dimensional imaging. By constructing a multi-channel detection array, the data volume of a measuring point is increased, and the fineness of three-dimensional imaging is improved; through primary field zero magnetic flux point adjustment, the influence of a primary magnetic field is counteracted, and the signal-to-noise ratio of data is improved.

Description

Technical Field

[0001] This invention relates to the field of geophysical information technology, and in particular to a method and apparatus for multi-channel transient electromagnetic detection at a tunnel face. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The transient electromagnetic method involves transmitting a pulsed magnetic field into the ground using either an ungrounded or grounded source, quickly shutting it off after the pulse stabilizes, and then observing the secondary induced eddy current field in the underground medium to detect underground targets. In tunnel construction, a transmitter and receiver are typically deployed ahead of the tunnel face to enable advanced tunnel detection.

[0004] To minimize damage to the tunnel face and reduce the impact on normal construction progress, transient electromagnetic transmission at the tunnel face is usually conducted using a loop source. However, due to the limited size of the tunnel working face, there are many limitations: ① The receiving part is close to the transmitting part, resulting in strong primary field interference; ② The size of the transmitting source is limited, which restricts the transmitting magnetic moment and the detection depth; ③ Noise interference is severe. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a multi-channel transient electromagnetic detection method and device for tunnel face. By constructing a multi-channel detection array, the amount of measurement data is increased, thereby enhancing the precision of three-dimensional imaging. Furthermore, by adjusting the zero flux point of the primary field, the influence of the primary magnetic field is offset, improving the data signal-to-noise ratio.

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

[0007] In a first aspect, the present invention provides a multi-channel transient electromagnetic detection method for tunnel face, comprising:

[0008] Plan horizontal survey lines at equal intervals on the tunnel face, and plan survey points at equal intervals on each survey line;

[0009] A multi-channel detection array consisting of transient electromagnetic receiving coils and transient electromagnetic transmitting coils was constructed, and the zero flux point of the primary field was adjusted. Specifically, the attenuated voltage signal of the transient electromagnetic receiving coil of each channel was observed, and the position of the transient electromagnetic receiving coil of each channel was adjusted along the axis connecting the center point of each frame of the transient electromagnetic transmitting coil and the geometric center of the frame, so that the observed value of the primary field attenuated voltage signal reached or approached zero.

[0010] After setting the emission parameters according to the detection depth and resolution requirements, a bipolar square wave is emitted, and the adjusted multi-channel detection array is used for point-by-point observation. A geometric network indexed by the survey line, survey point, and channel number is constructed based on the observation data, and three-dimensional imaging with multi-channel combination is carried out accordingly.

[0011] As an alternative implementation, the survey points on different survey lines are vertically aligned.

[0012] As an alternative implementation, the emission parameters include emission voltage and emission frequency.

[0013] As an alternative implementation, one period of the bipolar square wave includes a sequential combination of four parts, which are a positive square wave, zero, a negative square wave, and zero. The time periods of the four parts are equal, and the absolute values of the amplitudes of the positive square wave and the negative square wave are equal.

[0014] As an alternative implementation, the transient electromagnetic emission coil includes an emission wire frame and an emission cable. The four side wire frames of the emission wire frame are grooved, and the emission cable is evenly wound in the grooves;

[0015] The transient electromagnetic receiving coil is a multi-channel circular hollow coil, and a circular hollow coil for each channel is arranged at each center point of the four side wire frames of the transient electromagnetic emission coil; the multi-channel circular hollow coil is a differential coil with different parameters.

[0016] As an alternative implementation, the multi-channel detection array after adjusting the zero magnetic flux point of the primary field is placed on the plane of the tunnel face. Keeping the transient electromagnetic emission coil and the transient electromagnetic receiving coil as a whole stationary, the geometric center of the transient electromagnetic emission coil is coincident with the survey point.

[0017] As an alternative implementation, after point-by-point observation, the observation data of each channel are averaged after being superimposed according to each emission waveform period; a geometric network is constructed based on the attenuated voltage data after superimposition of each survey point and each channel.

[0018] In a second aspect, the present invention provides a multi-channel transient electromagnetic detection device for a tunnel face, including a transient electromagnetic emission coil, a transient electromagnetic receiving coil, and a transceiver integrated machine;

[0019] The transient electromagnetic emission coil includes an emission wire frame and an emission cable. The four side wire frames of the emission wire frame are grooved, and the emission cable is evenly wound in the grooves;

[0020] The transient electromagnetic receiving coil is placed at each center point of the four-sided wire frame of the transient electromagnetic transmitting coil, and a zero-adjustment device is provided between the transient electromagnetic transmitting coil and the transient electromagnetic receiving coil. The zero-adjustment device is used to adjust the position of the transient electromagnetic receiving coil of each channel along the line axis connecting the center point of each wire frame of the transient electromagnetic transmitting coil and the geometric center of the wire frame when adjusting the primary field zero flux point, until the observed value of the primary field attenuation voltage signal of the transient electromagnetic receiving coil of each channel reaches or approaches zero.

[0021] The transceiver unit is used to transmit bipolar square waves after setting the transmission parameters according to the detection depth and resolution requirements, and to receive observation data. Based on the observation data, a geometric network indexed by measurement lines, measurement points and channel numbers is constructed to perform multi-channel joint three-dimensional imaging. The observation data is obtained by point-by-point observation by a multi-channel detection array composed of transient electromagnetic transmitting coils and transient electromagnetic receiving coils after adjusting the primary field zero flux point.

[0022] As an alternative implementation, the transient electromagnetic receiving coil is a multi-channel circular hollow coil, with each channel circular hollow coil placed at the center point of the four-sided frame of the transient electromagnetic transmitting coil; the multi-channel circular hollow coil is a differential coil with different parameters.

[0023] As an alternative implementation, the zeroing device includes a slide rail body, a slider, a limit block, and a zeroing screw;

[0024] The slide rail body is located at the center points of the four-sided frame of the transient electromagnetic transmitting coil. The slide rail body has a slide rail groove inside. The slider is connected to the transient electromagnetic receiving coil and is located on the slide rail groove and moves along the slide rail groove.

[0025] One end of the slide rail body is provided with a limiting block, which is used to limit the maximum displacement of the slider. By disassembling the limiting block, the transient electromagnetic receiving coil can be disassembled and replaced with a transient electromagnetic receiving coil with different parameters. The other end is provided with a zero-adjustment screw. A screw rod passes through the inside of the slider. One end of the screw rod is located on the limiting block, and the other end is connected to the zero-adjustment screw. When the zero-adjustment screw is rotated, the slider moves along the slide rail groove, which drives the transient electromagnetic receiving coil to move along the axis connecting the center points of the four sides of the transient electromagnetic transmitting coil frame with the geometric center of the frame.

[0026] As an alternative implementation, the transceiver includes a transmitting section and a receiving section; the transmitting section is connected to a transient electromagnetic transmitting coil, and the receiving section is connected to a transient electromagnetic receiving coil;

[0027] The transmitting and receiving sections communicate via three signal lines. The first line is the start signal line; when transmission is initiated, the level of this signal line changes, simultaneously activating reception. The second line is the reception completion signal line; after data observation and superposition are completed, the receiving section is shut down, and the level of this signal line changes, simultaneously shutting down the transmitting section. The third line is an analog second pulse signal line; this signal line is pulled high for 10ms every second to achieve timing synchronization between the transmitting and receiving sections.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention proposes a multi-channel transient electromagnetic detection method and device for tunnel faces, including planning and marking survey lines and points on the tunnel face; emitting bipolar square waves after setting the transmission voltage and frequency according to the required detection depth and resolution; placing multi-channel transient electromagnetic receiving coils on the transient electromagnetic transmitting frame, with 1 to 4 channels depending on actual needs, each channel equipped with transient electromagnetic receiving coils of different parameters; adjusting the zero-flux position of the transient electromagnetic receiving coils; activating the transmitter against the tunnel face plane to conduct continuous observation of attenuated voltage. The transmission and receiving systems maintain consistency in observation timing through synchronization; keeping the transient electromagnetic transmitting and receiving coils stationary, after continuous observation for a specific time, the observation data from each channel are superimposed to cancel noise; data processing and interpretation are performed on each channel separately; multi-channel joint three-dimensional imaging is performed, taking into account the detection requirements of different depths and bandwidth ranges, effectively improving the data signal-to-noise ratio, enhancing interpretation accuracy and imaging resolution, achieving a large transmitting magnetic moment and detection depth, and possessing strong noise suppression capabilities and a high receiving signal-to-noise ratio.

[0030] This invention observes the attenuated voltage signal of the transient electromagnetic receiving coil of each channel, and adjusts the position of the transient electromagnetic receiving coil of each channel along the axis connecting the center point of each frame of the transient electromagnetic transmitting coil and the geometric center of the frame, so that the observed value of the primary field attenuated voltage signal reaches or approaches zero. Through the above-mentioned adjustment of the primary field zero flux point, rapid magnetic flux zeroing is achieved, the influence of the primary magnetic field is counteracted, and the data signal-to-noise ratio is improved.

[0031] This invention constructs a multi-channel detection array, which transmits once and receives data from multiple channels simultaneously, increasing the amount of data at the measurement points. When equipped with coils of different parameters, it can meet the detection requirements of different depths and bandwidth ranges, significantly improving the precision of three-dimensional imaging and facilitating the characterization of anomalies.

[0032] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. Attached Figure Description

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0034] Figure 1 This is a flowchart of the multi-channel transient electromagnetic detection method for tunnel face provided in Embodiment 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the layout of the tunnel face survey lines and survey points provided in Embodiment 1 of the present invention;

[0036] Figure 3 This is a schematic diagram of the transient electromagnetic transmitting coil and transient electromagnetic receiving coil provided in Embodiment 1 of the present invention;

[0037] Figure 4 This is a schematic diagram of the overall structure of the multi-channel transient electromagnetic detection device at the tunnel face provided in Embodiment 2 of the present invention;

[0038] Figure 5 This is a schematic diagram of the zeroing device provided in Embodiment 2 of the present invention;

[0039] Among them, 1. transient electromagnetic transmitting coil, 2. transient electromagnetic receiving coil, 4. transceiver, 3. signal transmission cable, 5. power supply, 6. slot, 7. slide rail body, 8. zero adjustment screw, 9. screw rod, 10. slide rail groove, 11. slider, 12. screw hole, 13. limit block. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0043] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0044] Example 1

[0045] like Figure 1 As shown, this embodiment provides a multi-channel transient electromagnetic detection method for tunnel faces, including the following steps:

[0046] Plan horizontal survey lines at equal intervals on the tunnel face, and plan survey points at equal intervals on each survey line;

[0047] A multi-channel detection array consisting of transient electromagnetic receiving coils and transient electromagnetic transmitting coils was constructed, and the zero flux point of the primary field was adjusted. Specifically, the attenuated voltage signal of the transient electromagnetic receiving coil of each channel was observed, and the position of the transient electromagnetic receiving coil of each channel was adjusted along the axis connecting the center point of each frame of the transient electromagnetic transmitting coil and the geometric center of the frame, so that the observed value of the primary field attenuated voltage signal reached or approached zero.

[0048] After setting the transmission parameters according to the detection depth and resolution requirements, a bipolar square wave is emitted. The adjusted multi-channel detection array is used to conduct point-by-point observations. Based on the observation data, a geometric network is constructed with measurement lines, measurement points, and channel numbers as indices, thereby performing multi-channel joint three-dimensional imaging.

[0049] like Figure 2 As shown, in this embodiment, horizontal survey lines are planned at equal intervals on the tunnel face, and survey points are planned at equal intervals on each survey line.

[0050] As an alternative implementation method, two survey lines are planned at equal intervals on the tunnel face, with a distance of two meters between the two survey lines. Equally spaced measuring points are planned on each survey line, with a distance of two meters between the measuring points on each survey line.

[0051] Understandably, the spacing between survey lines and the spacing between survey points on each survey line can be adaptively designed according to the actual situation, and is not limited to two meters.

[0052] As an alternative implementation, the measurement points on different survey lines are vertically aligned. The survey lines are numbered and marked in order from bottom to top, and the measurement points are numbered and marked in order from left to right.

[0053] In this embodiment, the emission parameters are set according to the detection depth and resolution requirements. The emission parameters include the emission voltage and the emission frequency.

[0054] As an alternative implementation, when a large detection depth is required, the emission voltage is increased and the emission frequency is decreased. Conversely, when high resolution in the shallow layer is required.

[0055] As an alternative implementation, in order to balance different detection depths within 100 meters and improve the signal-to-noise ratio of the data, the emission voltage is set to 10V and the emission frequency is 25Hz.

[0056] In this embodiment, a bipolar square wave is emitted according to the set emission parameters; the bipolar square wave is the emission current waveform, and one cycle includes a sequential combination of four parts, which are a positive square wave, zero, a negative square wave, and zero. The time periods of the four parts are equal, and the absolute values of the amplitudes of the positive square wave and the negative square wave are equal.

[0057] In this embodiment, a multi-channel detection array composed of a transient electromagnetic receiving coil and a transient electromagnetic transmitting coil is built; as Figure 3 shown, specifically:

[0058] The transient electromagnetic transmitting coil 1 is composed of a transmitting wire frame and a transmitting cable. The transmitting wire frame is a "field"-shaped square frame, and the four corners are chamfered;

[0059] The four side frames of the transmitting wire frame are grooved, and the transmitting cable is evenly wound in the groove 6, and a cable joint is left. The cable joint is encapsulated as an aviation plug.

[0060] The transient electromagnetic receiving coil 2 is a multi-channel circular hollow coil. Each channel circular hollow coil is placed at the center points of the four side wire frames of the transient electromagnetic transmitting coil 1. A total of four-channel circular hollow coils can be placed on the four side wire frames.

[0061] The transient electromagnetic receiving coil 2 is placed on the center of the four side wire frames of the transient electromagnetic transmitting coil 1. According to the requirements of data accuracy and detection efficiency, 1 to 4 channels can be carried, that is, carried on 1 side to 4 sides of the four side wire frames of the transient electromagnetic transmitting coil 1. In this embodiment, 4 channels are carried. The more channels, the higher the accuracy and detection efficiency;

[0062] At the same time, the zero-flux position of the transient electromagnetic receiving coil 2 is adjusted. The emission source is placed close to the tunnel face plane to start the emission, and continuous observation of the attenuation voltage signal is carried out. The consistency of the observation time sequence is maintained through synchronization between emission and reception.

[0063] As an alternative implementation, the 4-channel transient electromagnetic receiving coil uses a hollow differential coil, and the observed attenuation voltage signal is a differential signal. Parameters such as the size, number of turns, and bandwidth of the transient electromagnetic receiving coil are different to adapt to the detection requirements of different depths and bandwidths.

[0064] As an alternative implementation, the circular hollow coil can be connected to an amplification and filtering circuit, which is used to amplify the weak induced voltage signal and filter out noise interference.

[0065] In this embodiment, the specific process of adjusting the zero magnetic flux point of the primary field includes: at a weak interference location, the transient electromagnetic receiving coil and the transient electromagnetic transmitting coil are vertically placed on the ground as a whole. The attenuation voltage signals of the transient electromagnetic receiving coils 2 of each channel are continuously observed. Along the axis connecting the center points of each side of the transient electromagnetic transmitting coil 1 to the geometric center of the wire frame, the plane position of the transient electromagnetic receiving coils 2 of each channel is adjusted by the zero-adjusting screw 8, so that the observed value of the primary field attenuation voltage signal reaches or approaches zero.

[0066] In this embodiment, according to the numbered measuring points, the transient electromagnetic transmitting coil 1 and the transient electromagnetic receiving coil 2 after adjusting the zero magnetic flux point of the primary field are placed on the tunnel face plane as a whole. Keeping the transient electromagnetic transmitting coil 1 and the transient electromagnetic receiving coil 2 stationary as a whole, the geometric center of the transient electromagnetic transmitting coil 1 is coincided with the measuring point, and the observations are carried out for each measuring point in sequence according to the numbering order.

[0067] In this embodiment, after continuously observing for a specific time at each measuring point, the observed data of each channel are superimposed and averaged according to each emission waveform period to cancel the noise; then, the attenuation voltage data after superimposition of each measuring point and each channel are extracted, and a geometric network of the face observation data is constructed with the measuring line, measuring point, and channel number as three-layer indexes; finally, the indexed data are respectively subjected to data processing and interpretation, so as to perform three-dimensional imaging of multi-channel combination.

[0068] Embodiment 2

[0069] This embodiment provides a multi-channel transient electromagnetic detection device for a tunnel face, as Figure 4 shown, including a transient electromagnetic transmitting coil 1, a transient electromagnetic receiving coil 2, a transceiver integrated machine 4, and a power supply 5.

[0070] In this embodiment, the transient electromagnetic transmitting coil 1 is composed of a transmitting wire frame and a transmitting cable. The transmitting wire frame is a "field"-shaped square frame with chamfers at the four corners; the four side frames of the transmitting wire frame are grooved, and the transmitting cable is evenly wound in the groove 6, and a cable joint is left. The cable joint is encapsulated as an aviation plug.

[0071] In this embodiment, the transient electromagnetic receiving coil 2 is a multi-channel circular hollow coil. Each channel of the circular hollow coil is placed at the center point of the four-sided frame of the transient electromagnetic transmitting coil 1. A total of four channels of circular hollow coils can be placed in the four-sided frame. The circular hollow coils can be connected to amplification and filtering circuits to amplify the weak induced voltage signal and filter out noise interference.

[0072] In this embodiment, the 4-channel transient electromagnetic receiving coil adopts an air-core differential coil, and the observed attenuated voltage signal is a differential signal. The size, number of turns, bandwidth and other parameters of the transient electromagnetic receiving coil are different to adapt to the detection requirements of different depths and bandwidths.

[0073] In this embodiment, a zero-adjustment device is provided between the transient electromagnetic transmitting coil 1 and the transient electromagnetic receiving coil 2, which is used to adjust the position of the transient electromagnetic receiving coil 2 of each channel when performing a field zero flux point adjustment.

[0074] like Figure 5 As shown, the zeroing device includes a slide rail body 7, a slider 11, a limit block 13, and a zeroing screw 8;

[0075] The slide rail body 7 is fixed at each center point of the four-sided wire frame of the transient electromagnetic transmitting coil 1. The slide rail body 7 is provided with a slide rail groove 10 inside. The slider 11 is disposed on the slide rail groove 10 and moves along the slide rail groove 10.

[0076] One end of the slide rail body 7 is provided with a limiting block 13. The limiting block 13 is used to limit the maximum displacement of the slider 11. By disassembling the limiting block, the transient electromagnetic receiving coil can be disassembled and replaced with a transient electromagnetic receiving coil with different parameters.

[0077] The slider 11 is provided with a screw hole 12, and the slider 11 is connected to the transient electromagnetic receiving coil 2 through the screw hole 12;

[0078] The slider 11 has internal threads for the screw 9 to pass through the inside of the slider 11. One end of the screw 9 is located on the limiting block 13, and the other end is located on the other end of the slide rail body 7.

[0079] A zero-adjustment screw 8 is provided on the other end of the slide rail body 7. The zero-adjustment screw 8 is connected to the other end of the screw 9 so that when the zero-adjustment screw 8 is rotated, the slider 11 drives the transient electromagnetic receiving coil 2 to move in different directions.

[0080] In this embodiment, the slider 11 and the transient electromagnetic receiving coil 2 as a whole can move freely along the slide rail groove 10 inside the slide rail body 7, so that the transient electromagnetic receiving coil 2 can move freely along the axis connecting the center point of each of the four sides of the transient electromagnetic transmitting coil 1 and the geometric center of the frame.

[0081] In this embodiment, during the assembly of the zeroing device, the limiting block 13 is removed, the slider 11 is connected to the transient electromagnetic receiving coil 2 and then inserted into the screw 9, and the screw 9 is connected to the zeroing screw 8 to fix the limiting block 13.

[0082] In this embodiment, the signal transmission cable 3 is composed of a four-core cable with aviation plugs at both ends, and one signal transmission cable for each channel.

[0083] In this embodiment, the transceiver 4 includes a transmitting section, a receiving section, a functional interface, and a screen.

[0084] The transmitting section is connected to the transient electromagnetic transmitting coil 1, which is connected to the transmitting section via an aviation plug. The transmitting section uses four silicon carbide field-effect transistors to build a full bridge, and uses the PL terminal of ZYNQ to control the switching of the four silicon carbide field-effect transistors in parallel, while controlling the dead time.

[0085] The receiving part is connected to the transient electromagnetic receiving coil 2 via signal transmission cable 3. The analog signal of the transient electromagnetic receiving coil is converted into digital signal by ADC analog-to-digital converter. DDR3 memory is used for high-speed caching. The file system on the PS terminal of ZYNQ is used to save the time-attenuation voltage data in files according to the test line number, test point number and channel number.

[0086] The functional interfaces include a channel interface, a Type-C interface, a transmitting coil interface, and a power supply interface; wherein, the channel interface connects to the transient electromagnetic receiving coil of each channel, the Type-C interface connects to a computer or mobile phone for data reading, the transmitting coil interface connects to the transient electromagnetic transmitting coil, and the power supply interface connects to power supply 5.

[0087] The screen is a touch screen, which allows users to set the transmission voltage, transmission current limit, and transmission frequency by touch, while also controlling the start and stop of transmission and monitoring the current transmission voltage, current waveform, and system temperature.

[0088] As an alternative implementation, the power supply 5 consists of a lithium battery and a power supply cable.

[0089] As one possible implementation, the transmitting and receiving sections communicate and synchronize via three signal lines. The first line is a start signal line; its level changes upon initiating transmission, simultaneously activating reception. The second line is a reception completion signal line; its level changes upon shutting down the receiving section after data observation and superposition, simultaneously shutting down the transmitting section. The third line is a simulated second pulse signal line; this line is pulled high for 10ms every second to achieve timing synchronization between the transmitting and receiving sections.

[0090] As an alternative implementation method, after the data observation is completed and the data superposition is finished, a pop-up message on the screen indicates that the reception is complete, and then the process moves to the next measurement point to start the observation.

[0091] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A tunnel face multi-channel transient electromagnetic detection method, characterized in that: Comprising: Equidistantly plan horizontal survey lines for the tunnel face and equidistantly plan survey points on each survey line; Build a multi-channel detection array composed of transient electromagnetic receiving coils and transient electromagnetic transmitting coils, and perform primary field zero-flux point adjustment; specifically: observe the decay voltage signals of the transient electromagnetic receiving coils of each channel, and adjust the positions of the transient electromagnetic receiving coils of each channel along the connecting axis between the center points of each wire frame of the transient electromagnetic transmitting coil and the geometric center of the wire frame, so that the observed value of the primary field decay voltage signal reaches or approaches zero; After setting the emission parameters according to the detection depth and resolution requirements, emit bipolar square waves, perform point-by-point observation with the adjusted multi-channel detection array, and construct a geometric network indexed by survey lines, survey points, and channel numbers based on the observed data, so as to perform three-dimensional imaging of multi-channel combination.

2. A tunnel face multi-channel transient electromagnetic detection method as claimed in claim 1, characterized in that: The survey points on different survey lines are vertically aligned.

3. A tunnel face multi-channel transient electromagnetic detection method as claimed in claim 1, characterized in that: The emission parameters include emission voltage and emission frequency; One period of the bipolar square wave includes a sequential combination of four parts, which are a positive square wave, zero, a negative square wave, and zero respectively. The time periods of the four parts are equal, and the absolute values of the amplitudes of the positive square wave and the negative square wave are equal.

4. A tunnel face multi-channel transient electromagnetic detection method as claimed in claim 1, characterized in that: The transient electromagnetic transmitting coil includes a transmitting wire frame and a transmitting cable. The four side wire frames of the transmitting wire frame are grooved, and the transmitting cable is evenly wound in the groove; The transient electromagnetic receiving coil is a multi-channel circular hollow coil, and a circular hollow coil of each channel is arranged at each center point of the four side wire frames of the transient electromagnetic transmitting coil; the multi-channel circular hollow coil is a differential coil with different parameters.

5. A tunnel face multi-channel transient electromagnetic detection method as claimed in claim 1, characterized in that: Place the multi-channel detection array after the primary field zero-flux point adjustment on the plane of the tunnel face, keep the overall transient electromagnetic transmitting coil and transient electromagnetic receiving coil stationary, and coincide the geometric center of the transient electromagnetic transmitting coil with the survey point.

6. A tunnel face multi-channel transient electromagnetic detection method as claimed in claim 1, characterized in that: After point-by-point observation, superimpose and average the observed data of each channel according to each emission waveform period; construct a geometric network based on the decay voltage data after superimposition of each survey point and each channel.

7. A multi-channel transient electromagnetic detection device for a tunnel face, characterized in that: Comprising: A transient electromagnetic transmitting coil, a transient electromagnetic receiving coil, and a transceiver integrated machine; The transient electromagnetic transmitting coil includes a transmitting wire frame and a transmitting cable. The four side wire frames of the transmitting wire frame are grooved, and the transmitting cable is wound in the groove; The transient electromagnetic receiving coil is placed at each center point of the four side wire frames of the transient electromagnetic transmitting coil, and a zero-adjusting device is provided between the transient electromagnetic transmitting coil and the transient electromagnetic receiving coil; the zero-adjusting device is used to adjust the positions of the transient electromagnetic receiving coils of each channel along the connecting axis between the center points of each wire frame of the transient electromagnetic transmitting coil and the geometric center of the wire frame during the primary field zero-flux point adjustment until the observed value of the primary field decay voltage signal of the transient electromagnetic receiving coils of each channel reaches or approaches zero; The transceiver is used to transmit bipolar square waves and receive observation data after setting the transmission parameters according to the detection depth and resolution requirements, and to construct a geometric network indexed by measurement lines, measurement points and channel numbers based on the observation data, so as to perform multi-channel combined three-dimensional imaging; the observation data is obtained by observing each measurement point through a multi-channel detection array composed of a transient electromagnetic transmitting coil and a transient electromagnetic receiving coil after adjusting the primary field zero flux point.

8. A tunnel face multi-channel transient electromagnetic detection device as claimed in claim 7, characterized in that: The transient electromagnetic receiving coil is a multi-channel circular hollow coil, and each channel circular hollow coil is placed at each center point of the four-side wire frame of the transient electromagnetic transmitting coil; the multi-channel circular hollow coil is a differential coil with different parameters.

9. A tunnel face multi-channel transient electromagnetic detection device as claimed in claim 7, characterized in that: The zero adjustment device comprises a slide rail body, a slider, a limit block and a zero adjustment screw; The slide rail body is arranged at each center point of the four-side wire frame of the transient electromagnetic transmitting coil, a slide rail groove is arranged inside the slide rail body, the slider is connected to the transient electromagnetic receiving coil, and the slider is arranged on the slide rail groove and moves along the slide rail groove; A limit block is provided at one end of the slide rail body, and the limit block is used to limit the maximum displacement of the slider. The transient electromagnetic receiving coil can be disassembled and replaced with a transient electromagnetic receiving coil with different parameters by disassembling the limit block; a zero adjustment screw is provided at the other end; a screw rod passes through the inside of the slider, one end of the screw rod is arranged on the limit block, and the other end is connected to the zero adjustment screw; when the zero adjustment screw is rotated, the slider moves along the slide rail groove, driving the transient electromagnetic receiving coil to move along the axis connecting the center points of the four-side wire frame of the transient electromagnetic transmitting coil and the geometric center of the wire frame.

10. A tunnel face multi-channel transient electromagnetic detection device as claimed in claim 7, characterized in that: The transceiver comprises a transmitting part and a receiving part; the transmitting part is connected to a transient electromagnetic transmitting coil, and the receiving part is connected to a transient electromagnetic receiving coil; The transmitting part and the receiving part communicate with each other through three signal lines; the first one is the start signal line. After the transmission is turned on, the level of the signal line changes and the reception is turned on at the same time; the second one is the reception completion signal line. After the data observation is completed and the data superposition is completed, the receiving part is turned off, the level of the signal line changes, and the transmitting part is turned off at the same time; the third one is the analog second pulse signal line. The signal line is pulled high for 10ms every second to achieve timing synchronization between the transmitting part and the receiving part.

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