Coaxial dual-mirror cavity detection device and method for high-speed rail tunnel

Abstract

The application discloses a coaxial double-mirror scanning device and method for high-speed rail tunnel lining cavity detection. The device comprises a high-energy pulsed laser, a laser Doppler vibrometer, a rotating frame, a first mirror and a second mirror mounted on the rotating frame, and a motor module for driving the rotating frame. The first mirror reflects the impact light beam to the lining surface to form an impact point, and the second mirror reflects the measurement light beam to the lining surface to form a vibration measurement point and guide back the vibration measurement return light. The two mirrors are installed on the same rotating frame and the relative rotation axis position is fixed, so that the two reflected light beams are synchronously deflected, the impact point and the vibration measurement point are synchronously moved at a constant interval, an impact-vibration measurement point pair with a fixed spatial relationship is formed, and cross-section circumferential scanning is realized. Combined with the longitudinal movement of the detection platform, a continuous scanning path is formed. The application also provides staggered continuous scanning and coverage unit compensation scanning, improves the uniformity and integrity of coverage, and is suitable for long-distance rapid nondestructive detection of high-speed rail tunnel cavities.

Description

Technical Field

[0001] This invention relates to a coaxial dual-mirror scanning device and method for detecting voids in the lining of high-speed railway tunnels. Background Technology

[0002] High-speed railway tunnels are a crucial component of high-speed railway lines. Their lining structures are constantly subjected to factors such as surrounding rock pressure, groundwater action, train vibration, temperature variations, and differences in construction quality. This can easily lead to hidden defects behind the lining, such as voids, cavities, and insufficient compaction. These defects are often difficult to detect through visual inspection in their early stages, but as they progress, they can cause lining cracking, water leakage, spalling, and even localized structural instability, affecting the structural safety of the high-speed railway tunnel and the reliability of the railway line. Therefore, how to conduct rapid, continuous, and large-scale detection of voids and other defects inside the lining of high-speed railway tunnels without compromising tunnel structure and operational safety is a critical problem that urgently needs to be solved in the field of tunnel maintenance and inspection.

[0003] Currently, the detection of voids in tunnel linings mainly includes methods such as core drilling, ground-penetrating radar (GPR), impact echo, manual tapping, and vibration testing. While core drilling can directly verify the internal condition of the lining, it is a localized, destructive testing method with low efficiency, making it unsuitable for continuous surveys of long-distance high-speed railway tunnels. GPR has high detection efficiency, but the results are significantly affected by the reinforcing mesh, the lining's moisture content, interface dielectric differences, and the tunnel's environmental conditions, easily leading to missed or false diagnoses of small-scale voids or areas of loose compaction. Impact echo and manual tapping methods require point-by-point excitation and measurement on the lining surface; their efficiency is limited by manual point placement, excitation consistency, and sensor deployment, making them unsuitable for the rapid, long-distance detection requirements of high-speed railway tunnels.

[0004] For the detection of voids in the lining of high-speed railway tunnels, the detection equipment not only needs to have a high ability to identify defects, but also needs to meet the requirements of long-distance, rapid, automated, and low-cost operation. Traditional point-by-point detection methods usually require inspectors to repeatedly set up measuring points or move the detection equipment inside the tunnel. The detection process is time-consuming, the work organization is complex, and it is difficult to form continuous and stable spatial detection results. If multiple measuring channels are used to cover the tunnel cross-section at the same time, although the detection range can be increased, the number of devices increases, the installation structure becomes more complex, the system calibration and maintenance workload is larger, and the overall manufacturing and operating costs are higher, which is not conducive to the large-scale application of high-speed railway tunnels.

[0005] During tunnel mobile inspection, the inspection platform moves longitudinally along the tunnel, and the inspection beam needs to rapidly change direction within the circumferential range of the tunnel cross-section to achieve continuous coverage of the lining surface. If the inspection platform only scans one cross-section at a fixed position and then moves to the next position to repeat the scan, although the measurement points are arranged relatively regularly, the inspection efficiency is low and it is not suitable for long-distance rapid general surveys of high-speed railway tunnels. If the inspection platform scans continuously during its movement, the scanning trajectory will be affected by factors such as the platform's operating speed, beam scanning frequency, triggering sequence, and tunnel cross-sectional morphology. Without a reasonable scanning control method, it is easy to cause repeated scanning or missed scanning in local areas, making it difficult to ensure complete coverage of the tunnel lining surface.

[0006] Therefore, it is necessary to propose a scanning device and method for detecting voids in the lining of high-speed railway tunnels that is simpler in structure, lower in cost, and more efficient in scanning. By employing a high-energy pulsed laser and a laser Doppler vibrometer, along with a coaxial rotating double-mirror structure, the laser impact beam and the laser vibration measurement beam can be synchronously reflected and controlled, so that the laser impact point and the vibration measurement point form an impact-vibration point pair with a preset spatial relationship on the tunnel lining surface. As the coaxial double-mirror rotates, the impact-vibration point pair can be rapidly scanned circumferentially along the cross-section of the high-speed railway tunnel; as the detection platform moves longitudinally along the tunnel, the circumferential scanning trajectory and the longitudinal movement trajectory are coupled, forming a continuous two-dimensional scanning coverage path on the tunnel lining surface, thereby achieving rapid, continuous, and full-coverage detection of void defects in the lining of high-speed railway tunnels.

[0007] Compared to methods relying on multiple measurement channels or complex mechanical arrangements to achieve cross-sectional coverage, this type of coaxial dual-mirror scanning method can reduce the number of measuring devices, simplify the system structure, and lower installation, commissioning, and maintenance costs. Furthermore, by coordinating the control of the mirror rotation angle, platform mileage, laser triggering time, and vibration measurement acquisition time, the consistency of scanning points and the spatial continuity of detection results can be improved. Therefore, researching a coaxial dual-mirror scanning device and moving scanning method for detecting voids in high-speed railway tunnel linings is of great significance for improving the efficiency of high-speed railway tunnel lining void detection, reducing the complexity of detection equipment, and achieving rapid long-distance surveys. Summary of the Invention

[0008] In the process of detecting internal cavities in high-speed railway tunnel linings, core drilling not only damages the lining structure but also has a limited detection range, making it difficult to meet the needs of long-distance continuous surveys of high-speed railway tunnels. While ground-penetrating radar (GPR) has high detection efficiency, it is prone to misjudgment or missed detection due to factors such as lining reinforcement, water content, interface dielectric differences, and on-site environmental interference. Although manual tapping and impact echo methods are simple in principle, they usually require point-by-point excitation and measurement, resulting in low detection efficiency. The detection results are greatly affected by manual operation, excitation consistency, and the layout of measurement points, making it difficult to achieve rapid, continuous, and full-coverage detection of the surface of high-speed railway tunnel linings.

[0009] To address the aforementioned technical problems, this invention proposes a coaxial dual-mirror scanning device and a moving scanning method for detecting voids in the lining of high-speed railway tunnels. The device employs a high-energy pulsed laser and a laser Doppler vibrometer as core detection equipment and incorporates a coaxial dual-mirror scanning module. This module includes a first mirror and a second mirror. The first mirror reflects the laser impact beam emitted by the high-energy pulsed laser, causing it to act on the surface of the high-speed railway tunnel lining and form a laser impact point. The second mirror reflects the measurement beam emitted by the laser Doppler vibrometer, causing it to act on the lining surface and form a vibration measurement point. Simultaneously, it receives the vibration feedback light returned from the vibration measurement point and guides the feedback light back to the laser Doppler vibrometer to complete the vibration velocity signal acquisition.

[0010] The coaxial dual-mirror scanning device for detecting voids in the lining of high-speed railway tunnels designed in this invention includes: High-energy pulsed lasers are used to emit laser shock beams; A laser Doppler vibration meter is used to emit a measurement beam and receive the vibration feedback light returned from the tunnel lining surface. A rotating frame having an axis of rotation; The first reflector is mounted on the rotating frame and its mirror surface is located in the optical path of the laser impact beam. It is used to reflect the laser impact beam onto the surface of the high-speed railway tunnel lining to form a laser impact point. The second reflector is mounted on the same rotating frame and its mirror surface is located in the optical path of the measurement beam. It is used to reflect the measurement beam to the surface of the high-speed railway tunnel lining to form a vibration measurement point and guide the vibration return light back to the laser Doppler vibration meter. The motor module is used to drive the rotating frame to rotate around the rotation axis; The first and second reflectors are fixed in position relative to the rotation axis on the rotating frame, so that the reflection directions of the laser impact beam and the measurement beam change synchronously with the rotating frame. The laser impact point and the vibration measurement point move synchronously at a preset distance, forming an impact-vibration measurement point pair with a fixed spatial relationship.

[0011] Furthermore, it also includes a reflector slide rail and a mounting bracket; the reflector slide rail is used to adjust the installation position of the first reflector and / or the second reflector to adjust the distance between the laser impact point and the vibration measurement point; the mounting bracket is used to support the motor module, the rotating frame, and the first and second reflectors, and to fix the entire coaxial dual-reflector scanning device on the detection platform.

[0012] Furthermore, the laser impact beam emitted by the high-energy pulsed laser is reflected by the first reflecting mirror and forms a local instantaneous impact excitation on the surface of the tunnel lining; the laser Doppler vibration meter receives the vibration velocity signal generated by the impact excitation at the vibration measurement point through the second reflecting mirror.

[0013] Furthermore, the motor module drives the rotating frame to rotate, causing the impact-vibration measurement point pair to move sequentially along the circumferential direction of the tunnel cross-section according to a preset angle sequence, forming a circumferential scan.

[0014] Furthermore, it also includes a detection platform, and the scanning device is fixed to the detection platform by a mounting bracket; when the detection platform moves longitudinally along the tunnel, the impact-vibration point pair forms a continuous scanning path covering the tunnel lining surface.

[0015] Based on the same inventive concept, this invention also designs a coaxial dual-mirror scanning method for detecting voids in the lining of high-speed railway tunnels, employing a coaxial dual-mirror scanning device for detecting voids in the lining of high-speed railway tunnels, including the following steps: Align the output beam of the high-energy pulsed laser with the first reflecting mirror and align the measuring beam of the laser Doppler vibrometer with the second reflecting mirror to complete the optical path alignment. Adjust the installation position of the first reflector and / or the second reflector to maintain a preset distance between the laser impact point and the vibration measurement point, and establish an impact-vibration measurement point pair; Set the scanning parameters, including the scanning angle range of the rotating frame, the scanning angle interval, the scanning cycle, and the trigger interval; The motor module drives the rotating frame to rotate, causing the first and second reflectors to rotate synchronously, and the impact-vibration measurement point pairs move sequentially along the circumferential direction of the tunnel cross section according to a preset angle sequence. When the rotating frame rotates to the target angle, it triggers the high-energy pulsed laser to emit a laser impact beam. After being reflected by the first reflector, the beam acts on the surface of the tunnel lining to form a laser impact point, generating instantaneous impact excitation. At the same time, the laser Doppler vibration meter emits a measurement beam to the vibration measurement point through the second reflector and receives the returned vibration feedback, demodulating and outputting the vibration velocity signal at the vibration measurement point.

[0016] Furthermore, the testing platform stays at a fixed mileage position. After the impact-vibration point pair completes the circumferential scan within that mileage section, the testing platform moves to the next mileage position and performs the circumferential scan of the next section.

[0017] Furthermore, the detection platform runs continuously along the longitudinal direction of the tunnel, while the motor module drives the rotating frame to perform circumferential reciprocating scanning. The impact-vibration measurement point pairs form a continuous zigzag scanning trajectory after the tunnel lining surface is unfolded into a plane.

[0018] Furthermore, during continuous moving scans, adjacent scan cycles employ staggered continuous scanning: Within the first scanning cycle, the impact-vibration measurement point pairs are scanned according to the first set of angle sequences; within the adjacent second scanning cycle, the impact-vibration measurement point pairs are shifted by a preset angle relative to the first set of angle sequences. The second set of angle sequence scans; the preset angle offset Based on the interval of adjacent circumferential scanning angles Confirmed, the preset angle offset Satisfying 0< < This ensures that the measurement points in the second scanning cycle are located between adjacent measurement points in the first scanning cycle, forming an interlaced coverage.

[0019] Furthermore, the continuous moving scan process also includes missed scan detection and compensation scan based on coverage cells: The unfolded tunnel lining surface is divided into several covering units, each covering unit corresponding to the longitudinal mileage interval and the circumferential angle interval; After each valid measurement is completed, the measurement point is mapped to the corresponding coverage unit according to the scanning angle of the reflector and the longitudinal position of the detection platform. If there is at least one measurement point within the coverage unit that meets the preset validity criteria, it is determined to be a covered unit; if there is no measurement point within the coverage unit, it is determined to be a missed scan unit; if there are measurement points within the coverage unit, but the vibration return quality or vibration velocity signal of all measurement points does not meet the preset validity criteria, it is determined to be a signal invalid unit.

[0020] The system outputs the longitudinal mileage and circumferential angle corresponding to the missed scan unit and the invalid signal unit, and performs local compensation scanning on the specified mileage range and circumferential angle range to convert the corresponding coverage unit into an effective coverage unit.

[0021] The present invention has the following advantages: 1) This invention proposes a coaxial dual-mirror scanning structure for detecting voids in high-speed railway tunnel linings. Two mirrors are simultaneously supported by the same rotating frame, enabling directional reflection and synchronous deflection of the high-energy laser shock beam and the LDV measurement beam, respectively. This structure integrates the excitation and measurement optical paths into a single rotating scanning unit, reducing the number of measuring devices while improving the integration of the device structure and the consistency of scanning control. This facilitates the development of a compact, easy-to-install, and mobile rapid scanning device for tunnel linings suitable for mobile inspection platforms.

[0022] 2) This invention utilizes the coaxial synchronous rotation of reflectors 1 and 2 to form a pre-defined spatial relationship between the laser impact point and the vibration measurement point on the surface of the high-speed railway tunnel lining, which then moves synchronously with the scanning angle. This method avoids the problem of unstable relative relationships between the excitation point and the measurement point during the scanning process, helps maintain the consistency of excitation and measurement conditions at different circumferential positions, and improves the comparability of vibration response data and the reliability of detection results.

[0023] 3) This invention proposes a continuous moving scanning method suitable for long-distance inspection of high-speed railway tunnels. By coupling the circumferential reciprocating scanning of the reflector module with the longitudinal movement of the inspection platform, the impact-vibration point pair forms a continuous scanning coverage trajectory on the unfolded surface of the tunnel lining. This method eliminates the need for the inspection platform to frequently stop at each cross-section, significantly improving the efficiency of long-distance tunnel inspection operations and providing an effective technical means for the rapid investigation of voids in the lining of high-speed railway tunnels.

[0024] 4) This invention further proposes a method for continuous scanning with staggered adjacent scanning cycles and a method for judging and compensating for missed scans based on coverage units. By staggering the distribution of measuring points in adjacent scanning cycles in the circumferential direction, the coverage uniformity during continuous moving scanning can be improved; by dividing the tunnel lining unfolding surface into sections consisting of longitudinal mileage L and circumferential angle... The defined coverage area allows for position output and local compensation scanning of missed and invalid signal units. This method improves scanning efficiency while enhancing the integrity of the scan coverage and reducing the risk of missed scans during long-distance mobile detection. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the coaxial dual-mirror scanning device of the present invention.

[0026] Figure 2 This is a schematic diagram illustrating the measurement principle of the coaxial dual-mirror scanning device of the present invention.

[0027] Figure 3 This is a schematic diagram comparing the static cross-sectional scanning and continuous moving scanning paths of the present invention.

[0028] Figure 4This is a schematic diagram of the continuous scanning with misalignment between adjacent scanning cycles according to the present invention.

[0029] Figure 5 This is a schematic diagram of the missed scan judgment and compensation scan based on the coverage unit of the present invention.

[0030] Figure 6 The following is the operational process for implementing this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through embodiments and with reference to the accompanying drawings. Embodiment 1 Embodiment 1 of this invention discloses a coaxial dual-mirror scanning device for detecting voids in the lining of high-speed railway tunnels, such as... Figure 1 As shown, it includes: High-energy pulsed lasers are used to emit laser shock beams; A laser Doppler vibration meter is used to emit a measurement beam and receive the vibration feedback light returned from the tunnel lining surface. A rotating frame having an axis of rotation; The first reflector is mounted on the rotating frame and its mirror surface is located in the optical path of the laser impact beam. It is used to reflect the laser impact beam onto the surface of the high-speed railway tunnel lining to form a laser impact point. The second reflector is mounted on the same rotating frame and its mirror surface is located in the optical path of the measurement beam. It is used to reflect the measurement beam to the surface of the high-speed railway tunnel lining to form a vibration measurement point and guide the vibration return light back to the laser Doppler vibration meter. The motor module is used to drive the rotating frame to rotate around the rotation axis; The first and second reflectors are fixed in position relative to the rotation axis on the rotating frame, so that the reflection directions of the laser impact beam and the measurement beam change synchronously with the rotating frame. The laser impact point and the vibration measurement point move synchronously at a constant distance, forming an impact-vibration measurement point pair with a fixed spatial relationship.

[0032] The implementation process of this invention is as follows: Figure 6 As shown: Step 1: Install the coaxial dual-mirror scanning device and complete the optical path alignment.

[0033] Before the inspection begins, the coaxial dual-mirror scanning device is installed on the external inspection platform. This scanning device includes mirror 1, mirror 2, mirror rails, a rotating frame, a motor module, and a mounting bracket. Mirror 1 reflects the high-energy laser impact beam emitted by the high-energy laser, causing the reflected beam to act on the surface of the high-speed railway tunnel lining and form a laser impact point. Mirror 2 reflects the LDV measurement beam emitted by the laser Doppler vibration meter, causing the reflected beam to act on the surface of the high-speed railway tunnel lining and form a vibration measurement point. Simultaneously, the vibration return light from the vibration measurement point can return along the original optical path, be reflected by mirror 2, and enter the laser Doppler vibration meter, where it demodulates and outputs the vibration velocity signal. The mounting bracket supports the motor module, the rotating frame, and mirrors 1 and 2, and fixes the entire scanning device to the external inspection platform to ensure structural stability during the inspection process. After the device is installed, the output beam of the high-energy laser is aligned with reflector 1 so that the high-energy laser shock beam can be reflected by reflector 1 and pointed to the surface of the high-speed railway tunnel lining; the measurement beam of the laser Doppler vibration meter is aligned with reflector 2 so that the LDV measurement beam can be reflected by reflector 2 and pointed to the surface of the high-speed railway tunnel lining, and the vibration return light from the vibration measurement point can be returned to the laser Doppler vibration meter by reflector 2.

[0034] Step 2: Adjust the position of the reflector to establish the impact-vibration measurement point pair.

[0035] After initial optical path alignment, the installation positions of the high-energy laser impact beam and the LDV measurement beam are adjusted by adjusting the reflector slide rail and the two reflectors to form two landing points with a preset spatial relationship on the tunnel lining surface. The reflector slide rail is used to adjust the installation positions of reflector 1 and / or reflector 2, thereby adjusting the landing point relationship of the two beams under assembly, calibration, or different detection distance conditions, so that the preset distance between the laser impact point and the vibration measurement point meets the detection requirements. Figure 2 As shown, the high-energy laser shock beam, after being reflected by mirror 1, forms a laser shock point on the lining surface. The LDV measurement beam, after being reflected by mirror 2, forms a vibration measurement point near the laser shock point. The laser shock point and the vibration measurement point together constitute a pair of shock-vibration measurement points. The spacing between the shock-vibration measurement point pairs can be set according to the range of the high-energy laser shock, the stability of the LDV backlight, and the detection distance to ensure that the vibration measurement points can stably collect the vibration response of the lining surface caused by the laser shock.

[0036] Step 3: Set the scan parameters.

[0037] After establishing the impact-vibration measurement point pair, the scanning angle range, scanning angle interval, scanning cycle, and trigger interval of the reflector module are set according to the cross-sectional area of ​​the high-speed railway tunnel, the target scanning density, and the operating speed of the detection platform. If a static cross-section scanning method is used, the circumferential scanning angle sequence for each cross-section is set; if a continuous moving scanning method is used, the longitudinal operating speed of the detection platform and the circumferential scanning cycle of the reflector module are set simultaneously, so that the circumferential scanning and longitudinal movement can form a scanning trajectory that meets the coverage requirements.

[0038] The scanning parameters are set as follows: the scanning angle range is determined by the initial circumferential angle of the tunnel section to be inspected. and termination circumferential angle Confirm; Scan angle interval Determined based on the target circumferential coverage interval; scanning cycle This refers to the time required for the reflector module to complete one scan within a preset scanning angle range. That is, from the initial circumferential angle... To the termination circumferential angle One scan cycle . The trigger interval can be determined by comprehensively calculating based on the scanning angle range, scanning angle interval, mirror rotation time of a single measuring point, and measurement time; It should be no less than the total time required to complete one high-energy laser shock, vibration velocity signal acquisition, and mirror rotation.

[0039] like Figure 3 As shown, in this embodiment, the longitudinal distance between two adjacent scanning trajectories in the same direction is defined as the longitudinal movement distance of the detection platform during a complete round-trip scan. In continuous moving scan mode, the operating speed of the detection platform is assumed to be... The longitudinal movement distance of the detection platform within one unidirectional scanning cycle is... The longitudinal movement distance of the detection platform during one complete round-trip scan is 2. Therefore, the maximum allowable longitudinal coverage spacing between adjacent scan trajectories is The optimal operating speed and scanning cycle of the detection platform should meet the following requirements. When the operating speed of the detection platform changes, the scanning cycle can be adjusted. Trigger interval or scanning angle interval This ensures that the longitudinal and circumferential spacing between adjacent scanning trajectories meets the preset coverage requirements.

[0040] Step 4: Perform a stationary section scan or a continuous moving scan.

[0041] like Figure 3As shown, when using the static cross-section scanning method, the detection platform remains at a fixed mileage position, and the motor module drives the rotating frame to rotate. Reflector 1 and Reflector 2 are mounted on the same rotating frame, maintaining a fixed spatial relationship relative to the rotation axis, and rotate synchronously around the same rotation axis under the drive of the motor module. Because the spatial positions of the two reflectors relative to the rotation axis are fixed and they rotate synchronously with the rotating frame, the reflection directions of the high-energy laser impact beam and the LDV measurement beam change synchronously. The laser impact point and the vibration measurement point move synchronously at a constant interval on the tunnel lining surface, forming an impact-vibration point pair. The impact-vibration point pair moves sequentially along the circumferential direction of the tunnel cross-section. After completing the cross-section scanning at that mileage position, the detection platform moves to the next mileage position and then performs the scanning of the next cross-section. This method is suitable for device calibration, local verification, and fine detection of suspected areas.

[0042] When using continuous moving scanning, the inspection platform moves continuously along the longitudinal direction of the high-speed railway tunnel, while the motor module drives the rotating frame to perform circumferential reciprocating scanning. At this time, the impact-vibration point pairs form a continuous zigzag scanning trajectory on the tunnel's unfolded surface. This method eliminates the need for the inspection platform to stop at each cross-section, making it suitable for long-distance, rapid scanning of high-speed railway tunnels.

[0043] Step 5: Perform laser shock and vibration measurements at the target angle.

[0044] During the scanning process, when the reflector module rotates to the target angle, the high-energy laser emits a high-energy laser impact beam. This beam, reflected by reflector 1, acts on the surface of the high-speed railway tunnel lining, generating instantaneous impact excitation at the laser impact point. Simultaneously, the LDV measurement beam, reflected by reflector 2, acts on the vibration measurement point, and the returning beam from the vibration measurement point returns to the laser Doppler vibrometer via reflector 2. The laser Doppler vibrometer demodulates the returning beam to obtain the vibration velocity signal at that measurement point. Because reflectors 1 and 2 are mounted on the same rotating frame and rotate synchronously, the laser impact point and the vibration measurement point maintain a relatively stable spatial relationship during the scanning process.

[0045] The working principle of the above measurement process is as follows: Figure 2 As shown, the measurement optical path of this invention includes a high-energy laser shock optical path and an LDV measurement optical path. The high-energy laser shock beam output from the high-energy laser is incident on reflector 1 and, after reflection, acts on the tunnel lining surface, forming a localized instantaneous shock excitation on the lining surface. The LDV measurement beam output from the laser Doppler vibrometer is incident on reflector 2 and, after reflection, acts on a vibration measurement point near the laser shock point. The lining surface generates minute vibrations after being excited by the laser shock, and the returning beam from the vibration measurement point returns to the laser Doppler vibrometer via reflector 2, forming a vibration velocity signal that can be used for analysis.

[0046] Step 6: Perform consecutive scans with staggered positions between adjacent scan cycles.

[0047] To improve coverage uniformity during continuous moving scans, methods such as... Figure 4 The method described is a staggered continuous scanning method for adjacent scanning cycles. In the first scanning cycle, the impact-vibration point pair is scanned according to a first set of angle sequences; in the adjacent second scanning cycle, the impact-vibration point pair is scanned according to a second set of angle sequences offset by a certain angle relative to the first set of angle sequences. This staggered continuous scanning occurs within the same forward scanning process, and does not refer to a second reverse scan after the entire tunnel inspection is completed.

[0048] Angular offset This refers to the additional offset angle added based on the first cycle, the magnitude of which is set according to the circumferential scan angle interval. Let the interval between adjacent circumferential scan angles in the first scan cycle be... Preferably, Take as This ensures that the measurement points in the second scanning cycle are located between adjacent measurement points in the first scanning cycle, forming staggered coverage, increasing circumferential coverage density, and reducing the risk of local missed scans due to continuous movement. Therefore, It is not set as a fixed constant, when When changes occur, Follow Adjustments will be made accordingly.

[0049] Testing platform running speed It mainly affects the spacing between adjacent scan cycles in the longitudinal direction. Instead of making a direct decision The angle value. When the operating speed of the detection platform changes, the scanning period T or the trigger interval can be adjusted. Control the longitudinal coverage spacing.

[0050] Step 7: Establish coverage cells and determine the scanning status.

[0051] like Figure 5 As shown, the unfolded surface of the high-speed railway tunnel lining is divided into several two-dimensional covering units according to the longitudinal mileage and circumferential angle. Each covering unit is determined by the corresponding longitudinal mileage interval and circumferential angle interval, where the length in the longitudinal direction is... The angular width in the circumferential direction is . and The distance between measurement points is determined based on the target detection resolution, preset measurement point spacing, and the maximum allowable missed scan spacing, and should generally not exceed the target scanning spacing in the corresponding direction. For example, under the detection condition where the target longitudinal scanning spacing is 0.1 m and the target circumferential angle spacing is 0.5°, the distance between measurement points can be determined by... and Set to 0.1 m and 0.5°; the above values ​​can be adjusted according to the actual detection resolution.

[0052] After each laser shock and vibration measurement is completed, the coverage unit to which the measurement point belongs is determined based on the longitudinal mileage and mirror scanning angle corresponding to that measurement on the detection platform. Specifically, when the longitudinal mileage of the measurement point is within the longitudinal mileage range corresponding to a certain coverage unit, and the mirror scanning angle is within the circumferential angle range corresponding to that coverage unit, the measurement point is assigned to that coverage unit. Each coverage unit represents the minimum spatial area on the tunnel lining surface that requires at least one effective measurement.

[0053] If there is at least one measurement point within a coverage unit that meets the requirements for vibration return quality and vibration velocity signal validity, then the coverage unit is determined to be a covered unit; if there is no measurement point within a coverage unit, then the coverage unit is determined to be a missed scan unit; if there are measurement points within a coverage unit, but none of the measurement points within the unit meet the preset validity requirements, then the coverage unit is determined to be a signal invalid unit.

[0054] Step 8: Output the missing locations and perform a compensation scan.

[0055] For coverage units identified as missed or invalid signal units, their corresponding longitudinal mileage range and circumferential angle range are output to pinpoint the location of the missing area. Based on the missing location information, the subsequent reflector scanning angle sequence, local scanning path, or detection platform operating status are adjusted to perform compensatory scanning on the corresponding area. Compensatory scanning is only performed on the local area where the missed or invalid signal unit is located, eliminating the need for repeated scanning of the entire tunnel or cross-section.

[0056] After the compensation scan is completed, the newly added measurement points are remapped to the corresponding coverage unit according to the measurement point mapping rules in step seven, and it is determined again whether there are measurement points in the coverage unit that meet the requirements of vibration return light quality and vibration velocity signal validity; if the validity requirements are met, the coverage unit is updated to a covered unit.

[0057] Through the above steps, this invention enables simultaneous scanning of impact excitation and vibration measurement of the surface of high-speed railway tunnel lining using a high-energy laser, a laser Doppler vibrometer, and a set of coaxial dual-mirror scanning modules. This method can be used for local scanning under static cross-sectional conditions, as well as for long-distance rapid scanning under continuous movement conditions. Furthermore, the uniformity and integrity of the scanning coverage can be improved through staggered continuous scanning and coverage unit compensation scanning.

[0058] Example 2 Based on the same inventive concept, this invention also discloses a coaxial dual-mirror scanning method for detecting voids in the lining of high-speed railway tunnels, employing the scanning device described in Embodiment 1, and including the following steps: Align the output beam of the high-energy pulsed laser with the first reflecting mirror and align the measuring beam of the laser Doppler vibrometer with the second reflecting mirror to complete the optical path alignment. Adjust the installation position of the first reflector and / or the second reflector to maintain a preset distance between the laser impact point and the vibration measurement point, and establish an impact-vibration measurement point pair; Set the scanning parameters, including the scanning angle range of the rotating frame, the scanning angle interval, the scanning cycle, and the trigger interval; The motor module drives the rotating frame to rotate, causing the first and second reflectors to rotate synchronously, and the impact-vibration measurement point pairs move sequentially along the circumferential direction of the tunnel cross section according to a preset angle sequence. When the rotating frame rotates to the target angle, it triggers the high-energy pulsed laser to emit a laser impact beam. After being reflected by the first reflector, the beam acts on the surface of the tunnel lining to form a laser impact point, generating instantaneous impact excitation. At the same time, the laser Doppler vibration meter emits a measurement beam to the vibration measurement point through the second reflector and receives the returned vibration feedback, demodulating and outputting the vibration velocity signal at the vibration measurement point.

[0059] The detection platform remains at a fixed mileage position. After the impact-vibration point pair completes the circumferential scan within that mileage section, the detection platform moves to the next mileage position and performs the circumferential scan of the next section. The detection platform moves continuously along the longitudinal direction of the tunnel, while the motor module drives the rotating frame to perform circumferential reciprocating scans. After the impact-vibration point pair unfolds the tunnel lining surface into a plane, it forms a continuous zigzag scanning trajectory.

[0060] During continuous moving scans, adjacent scan cycles employ staggered continuous scanning: Within the first scanning cycle, the impact-vibration measurement point pairs are scanned according to the first set of angle sequences; within the adjacent second scanning cycle, the impact-vibration measurement point pairs are shifted by a preset angle relative to the first set of angle sequences. The second set of angular sequence scans; The interval between adjacent circumferential scanning angles in the first scanning cycle Half of the measurement points in the second scanning cycle are located between adjacent measurement points in the first scanning cycle, forming staggered coverage.

[0061] The continuous moving scan process also includes missed scan detection and compensation scan based on coverage cells: The unfolded tunnel lining surface is divided into several covering units, each covering unit corresponding to the longitudinal mileage interval and the circumferential angle interval; After each valid measurement is completed, the measurement point is mapped to the corresponding coverage unit according to the scanning angle of the reflector and the longitudinal position of the detection platform. If there is a valid measurement point within the coverage unit, it is determined to be covered; if there is no valid measurement point, it is determined to be a missed scan unit; if the vibration return quality or vibration velocity signal does not meet the preset validity criteria, it is determined to be an invalid signal unit. The system outputs the longitudinal mileage and circumferential angle corresponding to the missed scan unit and the invalid signal unit, and performs local compensation scanning on the specified mileage range and circumferential angle range to convert the corresponding coverage unit into an effective coverage unit.

[0062] Since the method described in Embodiment 2 of this invention is the method used in the coaxial dual-reflector scanning device for detecting voids in the lining of high-speed railway tunnels as described in Embodiment 1 of this invention, those skilled in the art can understand the specific structure and variations of the system based on the scanning device described in Embodiment 1 of this invention, and therefore will not be repeated here. All methods used in the scanning device of Embodiment 1 of this invention fall within the scope of protection of this invention.

[0063] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A coaxial dual-mirror scanning device for detecting voids in the lining of high-speed railway tunnels, characterized in that, include: High-energy pulsed lasers are used to emit laser shock beams; A laser Doppler vibration meter is used to emit a measurement beam and receive the vibration feedback light returned from the tunnel lining surface. A rotating frame having an axis of rotation; The first reflector is mounted on the rotating frame and its mirror surface is located in the optical path of the laser impact beam. It is used to reflect the laser impact beam onto the surface of the high-speed railway tunnel lining to form a laser impact point. The second reflector is mounted on the same rotating frame and its mirror surface is located in the optical path of the measurement beam. It is used to reflect the measurement beam to the surface of the high-speed railway tunnel lining to form a vibration measurement point and guide the vibration return light back to the laser Doppler vibration meter. The motor module is used to drive the rotating frame to rotate around the rotation axis; The first and second reflectors are fixed in position relative to the rotation axis on the rotating frame, so that the reflection directions of the laser impact beam and the measurement beam change synchronously with the rotating frame. The laser impact point and the vibration measurement point move synchronously at a preset distance, forming an impact-vibration measurement point pair with a fixed spatial relationship.

2. The coaxial dual-mirror scanning device according to claim 1, characterized in that: It also includes a reflector slide rail and a mounting bracket; the reflector slide rail is used to adjust the installation position of the first reflector and / or the second reflector to adjust the distance between the laser impact point and the vibration measurement point; the mounting bracket is used to support the motor module, the rotating frame, and the first and second reflectors, and to fix the entire coaxial dual-reflector scanning device on the detection platform.

3. The coaxial dual-mirror scanning device according to claim 1, characterized in that: The laser impact beam emitted by the high-energy pulsed laser is reflected by the first reflecting mirror and forms a local instantaneous impact excitation on the surface of the tunnel lining; the laser Doppler vibration meter receives the vibration velocity signal generated by the impact excitation at the vibration measurement point through the second reflecting mirror.

4. The coaxial dual-mirror scanning device according to claim 1, characterized in that: The motor module drives the rotating frame to rotate, causing the impact-vibration measurement points to move sequentially along the circumferential direction of the tunnel cross-section according to a preset angle sequence, forming a circumferential scan.

5. The coaxial dual-mirror scanning device according to claim 1, characterized in that: It also includes a detection platform, and the scanning device is fixed to the detection platform by a mounting bracket; when the detection platform moves longitudinally along the tunnel, the impact-vibration point pair forms a continuous scanning path covering the tunnel lining surface.

6. A coaxial dual-mirror scanning method for detecting voids in the lining of high-speed railway tunnels, employing the coaxial dual-mirror scanning device as described in any one of claims 1 to 5, characterized in that... Includes the following steps: Align the output beam of the high-energy pulsed laser with the first reflecting mirror and align the measuring beam of the laser Doppler vibrometer with the second reflecting mirror to complete the optical path alignment. Adjust the installation position of the first reflector and / or the second reflector to maintain a preset distance between the laser impact point and the vibration measurement point, and establish an impact-vibration measurement point pair; Set the scanning parameters, including the scanning angle range of the rotating frame, the scanning angle interval, the scanning cycle, and the trigger interval; The motor module drives the rotating frame to rotate, causing the first and second reflectors to rotate synchronously, and the impact-vibration measurement point pairs move sequentially along the circumferential direction of the tunnel cross section according to a preset angle sequence. When the rotating frame rotates to the target angle, it triggers the high-energy pulsed laser to emit a laser impact beam. After being reflected by the first reflector, the beam acts on the surface of the tunnel lining to form a laser impact point, generating instantaneous impact excitation. At the same time, the laser Doppler vibration meter emits a measurement beam to the vibration measurement point through the second reflector and receives the returned vibration feedback, demodulating and outputting the vibration velocity signal at the vibration measurement point.

7. The coaxial dual-mirror scanning method according to claim 6, characterized in that: The testing platform stays at a fixed mileage position. After the impact-vibration point pair completes the circumferential scan within the section of that mileage, the testing platform moves to the next mileage position and performs the circumferential scan of the next section.

8. The coaxial dual-mirror scanning method according to claim 6, characterized in that: The detection platform runs continuously along the longitudinal direction of the tunnel, while the motor module drives the rotating frame to perform circumferential reciprocating scanning. The impact-vibration measurement point pairs form a continuous zigzag scanning trajectory after the tunnel lining surface is unfolded into a plane.

9. The coaxial dual-mirror scanning method according to claim 8, characterized in that: During continuous moving scans, adjacent scan cycles employ staggered continuous scanning: Within the first scanning cycle, the impact-vibration measurement point pairs are scanned according to the first set of angle sequences; within the adjacent second scanning cycle, the impact-vibration measurement point pairs are shifted by a preset angle relative to the first set of angle sequences. The second set of angle sequence scans; the preset angle offset Based on the interval of adjacent circumferential scanning angles Confirmed, the preset angle offset Satisfying 0< < This ensures that the measurement points in the second scanning cycle are located between adjacent measurement points in the first scanning cycle, forming an interlaced coverage.

10. The coaxial dual-mirror scanning method according to claim 9, characterized in that: The continuous moving scan process also includes missed scan detection and compensation scan based on coverage cells: The unfolded tunnel lining surface is divided into several covering units, each covering unit corresponding to the longitudinal mileage interval and the circumferential angle interval; After each valid measurement is completed, the measurement point is mapped to the corresponding coverage unit according to the scanning angle of the reflector and the longitudinal position of the detection platform. If there is at least one measurement point in the coverage unit that meets the preset validity criteria, it is determined to be a covered unit; if there is no measurement point in the coverage unit, it is determined to be a missed scan unit; if there are measurement points in the coverage unit, but the vibration return quality or vibration velocity signal of all measurement points does not meet the preset validity criteria, it is determined to be a signal invalid unit. The system outputs the longitudinal mileage and circumferential angle corresponding to the missed scan unit and the invalid signal unit, and performs local compensation scanning on the specified mileage range and circumferential angle range to convert the corresponding coverage unit into an effective coverage unit.

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