A system and method for monitoring the health of a subway tunnel structure by using a vehicle-mounted 3D ultrasonic wave

Abstract

The application discloses a kind of vehicle-mounted 3D ultrasonic monitoring subway tunnel structure health's system and method, it is related to subway tunnel structure health monitoring technical field, including vehicle-mounted ultrasonic sensor array device, ultrasonic controller based on chip and computer-based subway tunnel structure health analysis module.The sensor array design of vehicle-mounted ultrasonic sensor array device of the present application can cover the entire cross section of tunnel, ensure the comprehensiveness of monitoring, and beamformer uses beamforming technology to enhance the signal from a particular direction.The beamforming technology can improve the directivity of the system, so that the sensor array can distinguish signals from different directions.After the ultrasonic signal after beamforming is wirelessly transmitted to the subway tunnel structure health analysis module, subsequent health degree evaluation can be based on three-dimensional imaging reconstruction results, and potential structural problems can be found in time, thereby improving the safety of subway operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of subway tunnel structure health monitoring, and in particular to a vehicle-mounted 3D ultrasonic wave system and method for monitoring subway tunnel structure health. BACKGROUND

[0002] As an important part of urban rail transit, the structure health of subway tunnels is directly related to the operation safety. With the acceleration of urbanization, the construction and operation mileage of subway tunnels are increasing, and the demand for monitoring the health of tunnel structures is becoming increasingly urgent. Unlike LiDAR and cameras, ultrasonic sensors are less affected by environmental factors such as insufficient light, dust, or temperature changes. Ultrasonic waves can also detect reflective or transparent surfaces such as glass or mirrors. Compared with other traditional monitoring methods such as manual inspection, level meters, total stations, GPS, displacement meters, etc., there are problems such as monitoring blind spots (only monitoring the surface, deep layers such as cavities, tunnel wall density, etc.), insufficient precision, and difficulty in meeting the high requirements of modern rail transit for safety and real-time performance.

[0003] Therefore, it is of great significance to develop a new monitoring method to make up for the shortcomings of traditional monitoring of the health status of tunnel structures, in order to ensure the safe operation of rail transit. SUMMARY

[0004] In order to solve the technical problems of subway tunnel structure health monitoring, the present application provides a vehicle-mounted 3D ultrasonic wave system and method for monitoring subway tunnel structure health. The technical scheme adopted is as follows:

[0005] A vehicle-mounted 3D ultrasonic wave system for monitoring subway tunnel structure health, comprising a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic wave controller, and a computer-based subway tunnel structure health analysis module. The vehicle-mounted ultrasonic sensor array device includes an autonomous mobile terminal, a sensor mounting platform, a plurality of ultrasonic sensor units, a beamformer, and a vehicle-mounted wireless data transceiver module. The bottom of the sensor mounting platform is mounted on the top of the autonomous mobile terminal. The sensor mounting platform is provided with a sensor mounting disc. The plurality of ultrasonic sensor units are respectively mounted around the sensor mounting disc. When the plurality of ultrasonic sensor units are working, the formed sensor array covers the cross section of the target tunnel. The beamformer respectively receives the ultrasonic wave signals communicated and interacted by the plurality of ultrasonic sensor units, and is wirelessly connected to the subway tunnel structure health analysis module through the vehicle-mounted wireless data transceiver module. The ultrasonic wave controller is communicatively connected to the autonomous mobile terminal, the plurality of sensor mounting platforms, and the plurality of ultrasonic sensor units. The subway tunnel structure health analysis module performs three-dimensional reconstruction on the subway tunnel structure based on the beamforming ultrasonic wave data of the plurality of vehicle-mounted ultrasonic sensor array devices, and outputs a three-dimensional reconstruction image.

[0006] By adopting the technical scheme, the sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the entire cross section of the tunnel during the movement of the autonomous mobile terminal in the target tunnel, ensuring the comprehensiveness of the monitoring and not missing any potential problem area. The multiple ultrasonic sensing units obtain 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. The beamformer enhances the signals from a specific direction while suppressing the signals from other directions using beamforming technology. The beamforming technology improves the directivity of the system, enabling the sensor array to distinguish signals from different directions.

[0007] After the beamformed ultrasonic signals are wirelessly transmitted to the subway tunnel structure health analysis module, the subway tunnel structure health analysis module can implement three-dimensional imaging reconstruction of the subway tunnel structure using 3D imaging technology. Subsequently, health assessment can be performed based on the three-dimensional imaging reconstruction results to timely detect potential structural problems, thereby improving the safety of subway operation.

[0008] Optionally, the sensor mounting platform includes a base, an electric turntable, an electric telescopic rod, and a sensor mounting disc. The base is detachably mounted on the top of the autonomous mobile terminal. The electric turntable is detachably mounted on the base. The bottom of the electric telescopic rod is detachably mounted on the rotating part at the top of the electric turntable. The middle part of one side of the sensor mounting disc is detachably mounted on the telescopic rod of the electric telescopic rod through a mounting block.

[0009] By adopting the technical scheme, the action adjustment of the electric turntable and the electric telescopic rod can adjust the angle and height of the sensor mounting disc, making the ultrasonic signal strength of the multiple ultrasonic sensing units mounted on the sensor mounting disc uniform, and enabling the sensor array formed by the multiple ultrasonic sensing units to cover the cross section of the current tunnel.

[0010] Optionally, if the ultrasonic signal strength feedback by the multiple ultrasonic sensing units is lower than the set ultrasonic intensity threshold, the ultrasonic controller controls the electric turntable and the electric telescopic rod to perform fine adjustment actions until the ultrasonic signal strength feedback by the multiple ultrasonic sensing units is greater than or equal to the set ultrasonic intensity threshold.

[0011] The fine adjustment action refers to the clockwise or counterclockwise rotation of the electric turntable by 1°, or the upward or downward movement of the piston rod of the electric telescopic rod by 1mm.

[0012] By adopting the technical scheme, if the ultrasonic signal feedback by the ultrasonic sensing unit is missing or the intensity is lower than the threshold, it may indicate that the cross section is not effectively covered. The ultrasonic controller calculates the mechanical instructions that need to be adjusted according to the results of the defect detection and sends them to the electric turntable and the electric telescopic rod to realize automatic adjustment of the adaptive sensor array.

[0013] Optionally, the ultrasonic sensing unit includes a housing, an ultrasonic transmitter, and an ultrasonic sensor. The housing is detachably mounted on a sensor mounting plate, with the extended axis of the housing passing through the center of the sensor mounting plate. The ultrasonic transmitter and the ultrasonic sensor are respectively located inside the housing, with the sensing heads facing outwards. The data output terminal of the ultrasonic sensor is communicatively connected to the signal input terminal of the beamformer, and the ultrasonic controller is communicatively connected to the ultrasonic sensor.

[0014] By adopting the above technical solution, the ultrasonic transmitter can emit ultrasonic signals toward the tunnel structure, the ultrasonic sensor receives the reflected signals, the data output terminals of multiple ultrasonic sensing units communicate and interact with the beamformer to receive the ultrasonic signals, and the beamformer processes the ultrasonic signals based on beamforming technology. The processed ultrasonic signals are more conducive to three-dimensional reconstruction.

[0015] Optionally, the subway tunnel structure health analysis module includes a computer-side wireless transceiver module, a memory, and a data analysis computer. The computer-side wireless transceiver module is wirelessly connected to the vehicle-side wireless data transceiver module. The memory is communicatively connected to the computer-side wireless transceiver module. The data analysis computer is communicatively connected to the memory. Based on beamforming ultrasonic data from multiple vehicle-side ultrasonic sensor arrays, the data analysis computer uses synthetic aperture focusing imaging to perform three-dimensional reconstruction of the subway tunnel structure and outputs a three-dimensional reconstructed image. The health of the subway tunnel structure is assessed based on the three-dimensional reconstructed image.

[0016] Optionally, the autonomous mobile terminal is an AGV electric trolley.

[0017] By adopting the above technical solutions, AGV electric vehicles can move precisely inside tunnels, and the batteries of AGV electric vehicles can also power the onboard ultrasonic sensor array device.

[0018] A method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves involves reconstructing a three-dimensional image of the internal structure of a target tunnel using such a system, and then assessing the structural health of the subway tunnel based on the three-dimensional image. The method includes the following steps:

[0019] Step 1: Control the autonomous mobile terminal to travel along the central axis of the target tunnel, and stop to perform ultrasonic data acquisition at set intervals;

[0020] Step 2: The ultrasonic controller controls the electric turntable and the electric telescopic rod to perform fine-tuning actions until the ultrasonic signal intensity fed back by multiple ultrasonic sensing units is greater than or equal to the set ultrasonic intensity threshold, so that the sensor array formed by multiple ultrasonic sensing units covers the cross-section of the target tunnel.

[0021] Step 3, multiple ultrasonic sensor units are turned on, and a beamformer enhances the ultrasonic signals from the target tunnel structure using beamforming technology, and sends the enhanced ultrasonic signal data to the subway tunnel structure health analysis module through the vehicle-mounted wireless data transceiver module.

[0022] Step 4, the data analysis computer processes the beamforming ultrasonic data enhanced by the beamforming technology using a synthetic aperture focusing imaging method, and outputs a three-dimensional reconstruction image of the subway tunnel structure using the synthetic aperture focusing imaging method.

[0023] Step 5, the autonomous mobile terminal travels to the end of the target tunnel along the central axis, and completes the three-dimensional reconstruction image of all cross sections.

[0024] Step 6, the data analysis computer extracts features for health assessment from the three-dimensional reconstruction images of all cross sections, including crack width, volume change and material degradation, and uses the extracted features to assess the health of the tunnel structure.

[0025] Optionally, in step 3, the calculation formula of beamforming is:

[0026]

[0027] where y ( t ) is the output ultrasonic signal after beamforming, w i is the weight vector of the beamformer; h i( t ) is the received signal after signal processing, x i( t ) is the channel received signal, s ( t ) is the target signal, a ( is the direction vector, and w H is the conjugate transpose of w.

[0028] Optionally, in step 4, the formula of the synthetic aperture focusing imaging method is:

[0029]

[0030] where I ( f, θ ) is the imaging result, y ( t ) is the output ultrasonic signal after beamforming, f is the ultrasonic signal frequency, θ is the angle of the ultrasonic signal, and N is the number of ultrasonic signal sampling points.

[0031] Optionally, in step 6, the formula for using the extracted features to assess the health of the tunnel structure is:

[0032] H = f ( F1, F2, ..., F n ) ;

[0033] Where H is the health assessment index of the tunnel structure, F1, F2, ..., F n It is the feature terms extracted from the 3D reconstructed image for health assessment, where n is the number of feature terms and f is the evaluation function; the evaluation function can be a linear combination, a weighted average, or a machine learning model.

[0034] In summary, the present invention has at least one of the following beneficial technical effects:

[0035] This invention provides a system and method for vehicle-mounted 3D ultrasonic monitoring of the structural health of subway tunnels. The sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the entire cross-section of the tunnel, ensuring comprehensive monitoring and preventing any potential problem areas from being missed. Multiple ultrasonic sensing units obtain 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. A beamformer uses beamforming technology to enhance signals from specific directions while suppressing signals from other directions. Beamforming technology improves the system's directivity, enabling the sensor array to distinguish signals from different directions.

[0036] After the ultrasonic signal is beamformed and wirelessly transmitted to the subway tunnel structure health analysis module, the module can use 3D imaging technology to realize three-dimensional imaging reconstruction of the subway tunnel structure. Subsequently, health assessment can be carried out based on the three-dimensional imaging reconstruction results to promptly identify potential structural problems, thereby improving the safety of subway operation. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the component connection principle of a vehicle-mounted 3D ultrasonic monitoring system for monitoring the structural health of subway tunnels according to the present invention;

[0038] Figure 2 This is a schematic diagram of the structural principle of the vehicle-mounted ultrasonic sensor array device for a system for monitoring the structural health of subway tunnels using vehicle-mounted 3D ultrasonic waves, according to the present invention.

[0039] Figure 3 This is a flowchart illustrating a method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves, according to the present invention.

[0040] Explanation of reference signs: 11, autonomous mobile terminal; 12, sensor mounting platform; 121, sensor mounting disc; 122, base; 123, motorized turntable; 124, motorized telescopic rod; 13, ultrasonic sensor unit; 131, housing; 132, ultrasonic transmitter; 133, ultrasonic sensor; 14, beamformer; 15, vehicle-mounted wireless data transceiver module; 2, ultrasonic controller; 3, subway tunnel structure health analysis module; 31, computer wireless transceiver module; 32, memory; 33, data analysis computer. DETAILED DESCRIPTION

[0041] The application will be further described in detail below with reference to the accompanying drawings.

[0042] The embodiment of the application discloses a system and method for monitoring the health of a subway tunnel structure by using a vehicle-mounted 3D ultrasonic wave.

[0043] Reference Figure 1 - Figure 3 , embodiment 1, a system for monitoring the health of a subway tunnel structure by using a vehicle-mounted 3D ultrasonic wave, comprising a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller 2 and a computer-based subway tunnel structure health analysis module 3, the vehicle-mounted ultrasonic sensor array device comprises an autonomous mobile terminal 11, a sensor mounting platform 12, a plurality of ultrasonic sensor units 13, a beamformer 14 and a vehicle-mounted wireless data transceiver module 15, the bottom of the sensor mounting platform 12 is mounted on the top of the autonomous mobile terminal 11, the sensor mounting platform 12 is provided with a sensor mounting disc 121, the plurality of ultrasonic sensor units 13 are respectively mounted around the sensor mounting disc 121, when the plurality of ultrasonic sensor units 13 work, the formed sensor array covers the cross section of the target tunnel, the beamformer 14 respectively receives the ultrasonic wave signals communicated and interacted by the plurality of ultrasonic sensor units 13, and is wirelessly connected to the subway tunnel structure health analysis module 3 through the vehicle-mounted wireless data transceiver module 15, the ultrasonic controller 2 is respectively connected in communication with the autonomous mobile terminal 11, the plurality of sensor mounting platforms 12 and the plurality of ultrasonic sensor units 13, the subway tunnel structure health analysis module 3 performs three-dimensional reconstruction on the subway tunnel structure based on the beamforming ultrasonic wave data of the plurality of vehicle-mounted ultrasonic sensor array devices, and outputs a three-dimensional reconstruction image.

[0044] The sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the entire cross-section of the tunnel during the movement of the autonomous mobile terminal 11 in the target tunnel, ensuring the comprehensiveness of the monitoring and not missing any potential problem areas. The multiple ultrasonic sensing units 13 obtain 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. The beamformer 14 uses beamforming technology to enhance signals from a specific direction while suppressing signals from other directions. Beamforming technology can improve the directivity of the system, allowing the sensor array to distinguish signals from different directions.

[0045] After the beamformed ultrasonic signals are wirelessly transmitted to the subway tunnel structure health analysis module 3, the subway tunnel structure health analysis module 3 can use 3D imaging technology to realize three-dimensional imaging reconstruction of the subway tunnel structure. Subsequent health degree evaluation can be based on the three-dimensional imaging reconstruction results to timely discover potential structural problems, thereby improving the safety of subway operation.

[0046] In embodiment 2, the sensor mounting platform 12 includes a base 122, a motorized turntable 123, a motorized telescopic rod 124, and a sensor mounting disc 121. The base 122 is detachably mounted on the top of the autonomous mobile terminal 11. The motorized turntable 123 is detachably mounted on the base 122. The bottom of the motorized telescopic rod 124 is detachably mounted on the rotating part at the top of the motorized turntable 123. The middle part of one side of the sensor mounting disc 121 is detachably mounted on the telescopic rod of the motorized telescopic rod 124 through the mounting block.

[0047] The action adjustment of the motorized turntable 123 and the motorized telescopic rod 124 can realize the adjustment of the angle and height of the sensor mounting disc 121, making the ultrasonic signal strength of the multiple ultrasonic sensing units 13 mounted on the sensor mounting disc 121 uniform, and making the sensor array formed by the multiple ultrasonic sensing units 13 cover the cross-section of the current tunnel.

[0048] In embodiment 3, if the ultrasonic signal strength feedback by the multiple ultrasonic sensing units 13 is lower than the set ultrasonic intensity threshold, the ultrasonic controller 2 controls the motorized turntable 123 and the motorized telescopic rod 124 to perform fine adjustment actions respectively until the ultrasonic signal strength feedback by the multiple ultrasonic sensing units 13 is greater than or equal to the set ultrasonic intensity threshold.

[0049] The fine adjustment action refers to the clockwise or counterclockwise rotation of the motorized turntable 123 by 1°, and the upward or downward movement of the piston rod of the motorized telescopic rod 124 by 1mm.

[0050] If the ultrasonic wave signal feedback by the ultrasonic sensing unit 13 is detected to be missing or the intensity is lower than a threshold value, it may indicate that the cross section is not effectively covered. The ultrasonic controller 2 calculates the mechanical instructions that need to be adjusted according to the results of the defect detection and sends them to the motorized turntable 123 and the motorized telescopic rod 124 to realize the automatic adjustment of the adaptive sensor array.

[0051] In embodiment 4, the ultrasonic sensing unit 13 includes a shell 131, an ultrasonic transmitter 132, and an ultrasonic sensor 133. The shell 131 is detachably mounted on the sensor mounting disc 121, and the axis extension line of the shell 131 passes through the center of the sensor mounting disc 121. The ultrasonic transmitter 132 and the ultrasonic sensor 133 are respectively arranged in the shell 131, and the sensing head faces outward. The data output end of the ultrasonic sensor 133 is communicatively connected to the signal input end of the beamformer 14, and the ultrasonic controller 2 is communicatively connected to the ultrasonic sensor 133.

[0052] The ultrasonic transmitter 132 can emit ultrasonic signals toward the tunnel structure, and the ultrasonic sensor 133 receives the reflected signals. The data output ends of the plurality of ultrasonic sensing units 13 receive the ultrasonic signals interactively communicated by the beamformer 14. The beamformer 14 processes the ultrasonic signals based on the beamforming technology, and the processed ultrasonic signals are more conducive to three-dimensional reconstruction.

[0053] In embodiment 5, the subway tunnel structure health analysis module 3 includes a computer-side wireless transceiver module 31, a memory 32, and a data analysis computer 33. The computer-side wireless transceiver module 31 is wirelessly communicatively connected to the vehicle-side wireless data transceiver module 15. The memory 32 is communicatively connected to the computer-side wireless transceiver module 31. The data analysis computer 33 is communicatively connected to the memory 32. Based on the beamforming ultrasonic data of the plurality of vehicle-mounted ultrasonic sensor array devices, the data analysis computer 33 adopts a synthetic aperture focusing imaging method to perform three-dimensional reconstruction on the subway tunnel structure and outputs a three-dimensional reconstruction image. The health of the subway tunnel structure is evaluated based on the three-dimensional reconstruction image.

[0054] In embodiment 6, the autonomous mobile terminal 11 is an AGV electric trolley.

[0055] The AGV electric trolley can accurately move in the tunnel, and the battery of the AGV electric trolley can also power the vehicle-mounted ultrasonic sensor array device.

[0056] In embodiment 7, a method for monitoring the health of a subway tunnel structure by a vehicle-mounted 3D ultrasonic wave includes the following steps:

[0057] Step 1, the autonomous mobile terminal 11 drives along the center axis of the target tunnel, stops every set distance to perform ultrasonic data collection action;

[0058] Step 2, the ultrasonic controller 2 controls the electric turntable 123 and the electric telescopic rod 124 to perform fine adjustment action until the ultrasonic signal intensity feedback by the plurality of ultrasonic sensing units 13 is greater than or equal to the set ultrasonic intensity threshold, so that the sensor array formed by the plurality of ultrasonic sensing units 13 covers the cross section of the target tunnel;

[0059] Step 3, the plurality of ultrasonic sensing units 13 are turned on, and the beamformer 14 enhances the ultrasonic signal from the target tunnel structure by using beamforming technology, and sends the enhanced ultrasonic signal data to the subway tunnel structure health analysis module 3 through the vehicle-mounted wireless data transceiver module 15;

[0060] Step 4, the data analysis computer 33 processes the beamforming ultrasonic data enhanced by the beamforming technology by using the synthetic aperture focusing imaging method, and outputs a three-dimensional reconstruction image by using the synthetic aperture focusing imaging method to three-dimensionally reconstruct the subway tunnel structure;

[0061] Step 5, the autonomous mobile terminal 11 drives along the center axis of the target tunnel to the end, and completes the three-dimensional reconstruction image of all cross sections;

[0062] Step 6, the data analysis computer 33 extracts features for health assessment from the three-dimensional reconstruction images of all cross sections, the features including crack width, volume change and material degradation, and uses the extracted features to evaluate the health degree of the tunnel structure.

[0063] In step 3 of embodiment 8, the calculation formula of beamforming is:

[0064]

[0065] Where y ( t ) is the output ultrasonic signal after beamforming, w i is the weight vector of the beamformer; h i( t ) is the received signal after signal processing, x i( t ) is the channel received signal, s ( t ) is the target signal, a ( is the direction vector, and w H is the conjugate transpose of w.

[0066] In step 4 of embodiment 9, the formula of the synthetic aperture focusing imaging method is:

[0067]

[0068] where I ( f, θ ) is the imaging result, y ( t ) is the output ultrasonic signal after beamforming, f is the ultrasonic signal frequency, θ is the angle of the ultrasonic signal, and N is the number of ultrasonic signal sampling points.

[0069] In step 6 of embodiment 10, the formula for evaluating the health of the tunnel structure using the extracted features is:

[0070] H = f ( F1, F2, …, F n ) ;

[0071] where H is the health evaluation index of the tunnel structure, F1, F2, …, F n are the feature items extracted from the three-dimensional reconstruction image for health evaluation, n is the number of feature items, and f is the evaluation function; the evaluation function is a linear combination, weighted average or machine learning model.

[0072] According to the health index HH, risk assessment can be performed to determine whether maintenance or reinforcement is needed.

[0073] The formula for risk assessment can be:

[0074] R = g(H);

[0075] where R is the risk assessment result, and gg is a function that converts the health index to a risk level.

[0076] Through the above steps and core formula, the health of the tunnel structure can be evaluated based on the three-dimensional reconstruction image of the tunnel cross section.

[0077] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made in accordance with the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A system for monitoring the health of a subway tunnel structure by using a vehicle-mounted 3D ultrasonic wave, characterized in that: The application relates to a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller (2) and a computer-based subway tunnel structure health analysis module (3), wherein the vehicle-mounted ultrasonic sensor array device comprises an autonomous mobile terminal (11), a sensor mounting platform (12), a plurality of ultrasonic sensing units (13), a beam former (14) and a vehicle-mounted wireless data transceiver module (15); the bottom of the sensor mounting platform (12) is mounted on the top of the autonomous mobile terminal (11); the sensor mounting platform (12) is provided with a sensor mounting disc (121); the plurality of ultrasonic sensing units (13) are respectively mounted around the sensor mounting disc (121); when the plurality of ultrasonic sensing units (13) work, a sensor array formed by the plurality of ultrasonic sensing units (13) covers the cross section of a target tunnel; the beam former (14) respectively receives ultrasonic signals communicated and interacted by the plurality of ultrasonic sensing units (13) and is wirelessly connected to the subway tunnel structure health analysis module (3) through the vehicle-mounted wireless data transceiver module (15); the ultrasonic controller (2) is connected in communication with the autonomous mobile terminal (11), the sensor mounting platform (12) and the plurality of ultrasonic sensing units (13); the subway tunnel structure health analysis module (3) performs three-dimensional reconstruction on a subway tunnel structure based on beam forming ultrasonic data of a plurality of vehicle-mounted ultrasonic sensor array devices and outputs a three-dimensional reconstruction image. The sensor mounting platform (12) comprises a base (122), an electric rotating disc (123), an electric telescopic rod (124) and a sensor mounting disc (121); the base (122) is detachably mounted on the top of the autonomous mobile terminal (11); the electric rotating disc (123) is detachably mounted on the base (122); the bottom of the electric telescopic rod (124) is detachably mounted on a rotating part on the top of the electric rotating disc (123); and the middle of one side of the sensor mounting disc (121) is detachably mounted on a telescopic rod of the electric telescopic rod (124) through a mounting block. If the ultrasonic signal strength fed back by the plurality of ultrasonic sensing units (13) is lower than a set ultrasonic intensity threshold value, the ultrasonic controller (2) controls the electric rotating disc (123) and the electric telescopic rod (124) to perform a fine adjustment action until the ultrasonic signal strength fed back by the plurality of ultrasonic sensing units (13) is greater than or equal to the set ultrasonic intensity threshold value. The fine adjustment action refers to that the electric rotating disc (123) rotates clockwise or counterclockwise by 1 degree, and the piston rod of the electric telescopic rod (124) rises or falls by 1 mm. The subway tunnel structure health analysis module (3) comprises a computer terminal wireless transceiver module (31), a memory (32) and a data analysis computer (33), the computer terminal wireless transceiver module (31) is in wireless communication connection with the vehicle-mounted wireless data transceiver module (15), the memory (32) is in communication connection with the computer terminal wireless transceiver module (31), and the data analysis computer (33) is in communication connection with the memory (32); the data analysis computer (33) is based on the beamforming ultrasonic wave data of the vehicle-mounted ultrasonic sensor array device, adopts a synthetic aperture focusing imaging method to perform three-dimensional reconstruction on the subway tunnel structure, outputs a three-dimensional reconstruction image, and evaluates the health of the subway tunnel structure based on the three-dimensional reconstruction image; A system for monitoring the health of a subway tunnel structure by using a vehicle-mounted 3D ultrasonic wave is adopted to reconstruct a three-dimensional image of the internal structure of a target tunnel, and evaluate the health of the subway tunnel structure based on the three-dimensional image of the internal structure of the target tunnel, comprising the following steps: Step 1: control the autonomous mobile terminal (11) to travel along the central axis of the target tunnel, and stop to perform ultrasonic wave data collection every certain distance; Step 2: the ultrasonic wave controller (2) controls the electric turntable (123) and the electric telescopic rod (124) to perform fine adjustment until the ultrasonic wave signal strength fed back by the multiple ultrasonic wave sensing units (13) is greater than or equal to a set ultrasonic wave strength threshold, so that the sensor array formed by the multiple ultrasonic wave sensing units (13) covers the cross section of the target tunnel; Step 3: the multiple ultrasonic wave sensing units (13) are turned on, the beamformer (14) enhances the ultrasonic wave signal from the target tunnel structure by using beamforming technology, and sends the enhanced ultrasonic wave signal data to the subway tunnel structure health analysis module (3) through the vehicle-mounted wireless data transceiver module (15); Step 4: the data analysis computer (33) processes the beamforming ultrasonic wave data enhanced by the beamforming technology by using a synthetic aperture focusing imaging method, performs three-dimensional reconstruction on the subway tunnel structure, and outputs a three-dimensional reconstruction image; Step 5: the autonomous mobile terminal (11) travels along the central axis of the target tunnel to the end, and completes the three-dimensional reconstruction image of all cross sections; Step 6: the data analysis computer (33) extracts features for health evaluation from all three-dimensional reconstruction images of the cross sections, the features include crack width, volume change and material degradation, and uses the extracted features to evaluate the health of the tunnel structure. 2.The system for monitoring the health of a subway tunnel structure according to claim 1, wherein: The ultrasonic wave sensing unit (13) comprises a shell (131), an ultrasonic wave transmitter (132) and an ultrasonic wave sensor (133), the shell (131) is detachably installed on the sensor mounting disc (121), the axis extension line of the shell (131) passes through the center of the sensor mounting disc (121), the ultrasonic wave transmitter (132) and the ultrasonic wave sensor (133) are respectively arranged in the shell (131) and have sensing heads facing outward, the data output end of the ultrasonic wave sensor (133) is in communication connection with the signal input end of the beamformer (14), and the ultrasonic wave controller (2) is in communication connection with the ultrasonic wave sensor (133).

3. The system for monitoring the health of a subway tunnel structure according to claim 2, characterized in that: The autonomous mobile terminal (11) is an AGV electric trolley.

4. The system for monitoring the health of a subway tunnel structure according to claim 3, characterized in that: In step 3, the formula for beamforming is: ； wherein is the outputted ultrasound signal after beamforming, is a weight vector of the beamformer; is the received signal after signal processing, is a channel received signal, is a target signal, is a direction vector, is is the conjugate transpose of 5. The system for monitoring the health of a subway tunnel structure according to claim 4, wherein: In step 4, the formula for synthetic aperture focusing imaging is: ； wherein is the imaging result, is the outputted ultrasonic signal after beamforming, f is the frequency of the ultrasonic signal, is the angle of the ultrasonic signal, and N is the number of sampling points of the ultrasonic signal. 6.The system for monitoring the health of a subway tunnel structure according to claim 5, wherein: In step 6, the formula for evaluating the health of the tunnel structure using the extracted features is: ； where H is a health assessment indicator of the tunnel structure, is a feature item extracted from the three-dimensional reconstructed image for health assessment, n is the number of feature items, and f is an assessment function; the assessment function is a linear combination, a weighted average, or a machine learning model.

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