Tunnel lining structure internal void disease detection equipment and detection method based on laser impact method

Abstract

The present invention relates to a tunnel lining structure internal hollow disease detection equipment and detection method based on a laser shock method, using a high-power short-pulse high-energy pulse laser transmitter to generate a laser shock wave to generate an instantaneous force on the tunnel lining surface, and then a laser Doppler vibrometer measures the vibration generated on the tunnel lining surface after the force is applied and records the vibration frequency, and through time-frequency domain conversion, removes various noise frequencies mixed in the result, analyzes the subtle changes in the vibration frequency, and once a hollow disease is found, immediately records the mileage of the disease and alarms, completing the rapid detection of the hollow inside the tunnel lining. Laser shock wave technology has the advantages of small heat-affected area, high pressure, superposition, non-contact, easy to accurately locate and control, etc.

Description

Technical Field

[0001] The invention relates to equipment and a method for detecting hollowing defects inside a tunnel lining structure based on a laser impact method. Background Art

[0002] During the construction of the tunnel, the natural geological conditions are complex and changeable, resulting in a harsh construction environment. If the standardization of the construction process and the strictness of the process cannot be guaranteed, the lining is prone to hollowing and cavity diseases. Under the influence of factors such as temperature changes, groundwater hydrostatic pressure and block drop load in the cavity area, the hollow lining is prone to leakage, cracking, frost damage and corrosion. In severe cases, tunnel collapse accidents may occur, seriously affecting the safety of the tunnel structure. Therefore, it is necessary to detect the hollowing disease inside the tunnel lining in a timely manner and carry out repair work in a timely manner to prevent the further aggravation of the hollowing disease, causing cracking and water seepage in the tunnel lining, cracking and block drop in the tunnel vault, and seriously threatening the safety and stability of the overall tunnel structure.

[0003] At present, the commonly used detection techniques are mainly divided into destructive testing and non-destructive testing. Destructive testing mainly involves drilling and coring. A drill is used to drill core samples from the lining structure to detect whether there are hollow defects in the lining. This method can intuitively detect whether there are defects inside the lining and has high reliability. However, this detection method has the following problems: (1) Drilling and coring can easily destroy the overall structure of the tunnel lining, causing damage to the tunnel drainage system and reducing the service life of the tunnel; (2) Drilling and coring cannot comprehensively check the tunnel lining structure on a large scale, and it is very easy to miss the hollow defects inside the lining; (3) The detection results are not representative and cannot generally reflect the overall health status of the tunnel lining structure.

[0004] Among the non-destructive testing methods, the most widely used is the Ground Penetrating Radar (GPR), which belongs to the category of electromagnetic wave detection methods. Its main principle is to use the propagation characteristics of high-frequency pulse electromagnetic waves in underground media and the wave laws of reflection and diffraction when encountering abnormal media to detect the distribution form and characteristics of underground target bodies. The main features of this method are non-destructive, efficient and fast. However, due to its detection principle and many interference factors such as the unevenness of the tunnel lining surface, there are currently the following problems: (1) The use of ground penetrating radar mainly judges the defects inside the lining by observing the changes in the dielectric constant of the material. For example, the lining in a certain area is not dense, the dielectric constant of this area is basically the same, and the change of the radar signal is almost unobservable; (2) The secondary lining of the tunnel is mostly cast in an integral manner using a steel frame. Various steel materials will seriously block the transmission of electromagnetic waves and also affect the reflected signal. (3) The complex conditions at the tunnel site and the unevenness of the tunnel surface will cause a serious decline in the quality of the collected data, and the effective signal will not be prominent, which is also easy to cause misjudgment or missed detection; (4) Since the dielectric constant of concrete or cement mortar is related to factors such as the quality, moisture content and density of the aggregate, before using ground penetrating radar detection, it is necessary to drill and sample the core or calibrate the dielectric constant based on the known thickness of the geological body, which is time-consuming and laborious.

[0005] The impact elastic wave method also utilizes the reflection characteristics of the signal. This method uses an impact hammer to continuously excite elastic wave signals along the secondary lining surface. When the elastic wave signal propagates in the structural medium, when it encounters loose media such as voids and void surfaces, the propagating elastic wave will produce wave reflections. The accelerometer installed on the surface measures the return signal and records it. At present, there are the following problems: (1) The measurement line needs to be arranged in advance during detection, which has low work efficiency; (2) The measurement sensitivity of the accelerometer is limited, and the detection effect of small-scale voids is poor.

[0006] Manual tapping is also a widely used method for detecting voids in tunnel linings. The main principle is to tap the tunnel wall with a handheld tapping hammer. When the echo is crisp, it means that the tunnel lining concrete is relatively dense; on the contrary, if the tapping sound is dull, it means that the lining concrete has voids. Manual tapping does not require complex precision equipment and is easy to operate, but it has the following problems: (1) The speed of manual tapping detection is affected by the proficiency of the operator and the inspection environment, the operation efficiency is low, and the operation speed is difficult to quantify and estimate; (2) Judging whether there is void disease inside the tunnel lining based on the tapping echo is mainly based on experience, which is prone to misjudgment and omission; (3) During the operation, suspected void diseases need to be manually marked and recorded. As the inspection mileage increases, a large amount of data gradually accumulates, which is complicated to check and organize, and the degree of digitalization and intelligence is low. (4) The power of manual tapping is limited, and generally only shallow voids can be found, which has great limitations.

[0007] Therefore, how to accurately and efficiently conduct comprehensive detection of internal void defects in tunnel linings has become a key issue that needs to be urgently resolved to ensure the safe operation of tunnels. Summary of the invention

[0008] In order to overcome the above-mentioned defects, the present invention designs a tunnel lining structure internal void disease detection equipment and detection method based on the laser impact method, which can accurately and efficiently perform comprehensive detection of tunnel lining internal void diseases.

[0009] The tunnel lining structure internal void disease detection equipment based on the laser impact method designed by the present invention is special in that it includes a measuring device, a data synchronization control acquisition module and a host computer, wherein the measuring device includes an inertial navigation unit, a laser ranging sensor, a laser Doppler vibrometer, a high-energy pulse laser transmitter and a mileage encoder; the data synchronization control acquisition module receives and synchronously processes the data collected by the measuring device and communicates with the host computer; the host computer collects and saves the uploaded data, pre-processes, displays in real time, gives an alarm and performs post-precision processing;

[0010] There are multiple laser Doppler vibrometers installed on the semicircular surface of the same vertical plane at the same interval angle, and the laser ranging sensor is also provided with multiple corresponding installations of the laser Doppler vibrometers; the high-energy pulse laser emitter scans the tunnel cross section at a certain angle within the required angle range by means of rotating mirror scanning; the impact plane of the laser impact is in front, and the measurement plane of the Doppler vibrometer optical head is in the back.

[0011] Furthermore, seven laser Doppler vibrometers are provided at intervals of 30°.

[0012] Furthermore, the scanning angle interval of the high-energy pulse laser emitter is 7.5°, and the number of impact positions is 25.

[0013] Furthermore, the laser Doppler vibrometer and laser ranging sensor at the same location are installed on the same servo mobile platform, the optical head of the laser Doppler vibrometer is fixedly installed at the center of the servo platform, and the laser ranging sensor is installed on the side of the same platform, and its own angle can be adjusted; the laser emission point of the lens plane of the laser ranging sensor and the laser emission point of the lens plane of the laser Doppler vibrometer optical head are in the same plane.

[0014] Furthermore, the laser Doppler vibrometer, inertial navigation unit, laser ranging sensor, encoder and high-energy pulse laser transmitter are all connected to the multi-source sensor data synchronization acquisition card through the RS44 interface, wherein the RS422 interface of the laser Doppler vibrometer has multiple optical lenses and single-channel corresponding control; the multi-source sensor data synchronization acquisition card is connected to the host computer.

[0015] Based on the same inventive concept, a tunnel lining structure internal hollow disease detection trolley based on the laser impact method includes a trolley body, and its special features are: the trolley body is equipped with tunnel lining structure internal hollow disease detection equipment based on the laser impact method, and the trolley is provided with two seats and a lifting platform;

[0016] The lifting platform is arranged at the rear of the vehicle, a semi-circular bracket is arranged on the lifting platform, and the laser Doppler vibrometer is installed on the semi-circular bracket at the same interval angle;

[0017] The high-energy pulse laser transmitter is installed in the middle of the trolley and realizes 180° scanning operation through turning refraction. The rotation of the rotating mirror is driven by a frameless motor.

[0018] The inertial navigation unit is installed just below the center of the lifting platform, and is also just below the intersection of the reverse extension lines of the optical head installation of the Doppler vibrometer.

[0019] Based on the same inventive concept, the present invention also designs a method for detecting small and medium span tunnels using a tunnel lining structure internal void disease detection device based on a laser impact method, which is special in that it includes the following steps:

[0020] Step 1: Power on the system and perform self-test to ensure that all sensors and modules can work normally;

[0021] Step 2: At a location where the tunnel lining surface is flat, turn on the laser Doppler vibrometer optical head and the laser distance sensor, and use the laser distance sensor to calibrate the distance measured by the laser Doppler vibrometer optical head;

[0022] Step 3: Adjust the position of the laser Doppler vibrometer to ensure that the optical heads of the first and last laser Doppler vibrometers are aligned with the tunnel arch foot and are flush with the arch foot.

[0023] Step 4: Control the tunnel lining structure internal void disease detection equipment based on the laser impact method to start running from the tunnel entrance, with a running speed range of 5-15km / h;

[0024] Step 5: The measuring equipment starts working. The first thing to do is to adjust the measurement focal length. The data synchronization control acquisition module sends a synchronization acquisition signal to the laser distance sensor to measure whether the distance between the current tunnel lining surface and the laser Doppler vibrometer optical head is the set standard value. If it is the set standard value after comparison, the next step is to measure the vibration frequency.

[0025] The specific workflow of vibration frequency measurement is that the data synchronization control acquisition module sends a synchronization signal to the laser Doppler vibrometer optical head, high-energy pulse laser transmitter, inertial navigation unit, host computer, and mileage encoder; after receiving the synchronization acquisition signal, the high-energy pulse laser transmitter emits a high-energy pulse laser to the galvanometer, which acts on the surface of the tunnel lining after rotation and refraction, causing the lining to produce micro-vibration. Subsequently, the laser Doppler vibrometer optical head, inertial navigation unit, and mileage encoder respectively collect measurement data at the same time, and the collected measurement data is transmitted back to the data synchronization control acquisition module, and then uploaded to the host computer by the data synchronization control acquisition module;

[0026] If the value is not the set standard value after comparison, adjust the position of the laser distance sensor so that the actual measured value it returns is equal to the preset standard value; at this time, the vibration frequency measurement can be carried out to complete a complete measurement process; with the operation of the 8 tunnel inspection trolley, the measurement process of step 5 will continue until the measurement is completed;

[0027] Step 6: The detection operation is completed and the system is powered off.

[0028] Based on the same inventive concept, the present invention also designs a method for detecting small and medium span tunnels using a tunnel lining structure internal hollow disease detection device based on a laser impact method, which is special in that it includes the following steps:

[0029] Step 1: Power on the system and perform self-test to ensure that all sensors and modules can work normally;

[0030] Step 2: At a location where the tunnel lining surface is flat, turn on the laser Doppler vibrometer optical head and the laser distance sensor, and use the laser distance sensor to calibrate the distance measured by the laser Doppler vibrometer optical head;

[0031] Step 3: Turn on the laser Doppler vibrometer at the corresponding position, and ensure that the first optical head is aligned with the arch foot on one side of the tunnel and is flush with the arch foot; the last laser Doppler vibrometer is the one closest to the first optical head at an angle of 127.5°;

[0032] Step 4: Control the tunnel lining structure internal void disease detection equipment based on the laser impact method to start running from the tunnel entrance, with a running speed range of 5-15km / h;

[0033] Step 5: The measuring equipment starts working. The first thing to do is to adjust the measurement focal length. The data synchronization control acquisition module sends a synchronization acquisition signal to the laser distance sensor to measure whether the distance between the current tunnel lining surface and the laser Doppler vibrometer optical head is the set standard value. If it is the set standard value after comparison, the next step is to measure the vibration frequency.

[0034] The specific workflow of vibration frequency measurement is that the data synchronization control acquisition module sends a synchronization signal to the laser Doppler vibrometer optical head, high-energy pulse laser transmitter, inertial navigation unit, host computer, and mileage encoder; after receiving the synchronization acquisition signal, the high-energy pulse laser transmitter emits a high-energy pulse laser to the galvanometer, which acts on the surface of the tunnel lining after rotation and refraction, causing the lining to produce micro-vibration. Subsequently, the laser Doppler vibrometer optical head, inertial navigation unit, and mileage encoder respectively collect measurement data at the same time, and the collected measurement data is transmitted back to the data synchronization control acquisition module, and then uploaded to the host computer by the data synchronization control acquisition module;

[0035] If after comparison it is not the set standard value, adjust the position of the laser ranging sensor so that the actual measured value it returns is equal to the pre-set standard value; at this time, the vibration frequency measurement can be performed to complete a complete measurement process; as the tunnel inspection trolley runs, the measurement process of step five will continue.

[0036] Step 5: After completing the inspection on one side of the tunnel, move the equipment to the other side of the tunnel and turn on the laser Doppler vibrometer at the corresponding position. The first one is close to 52.5° horizontal angle, and the last one is 180°. Then proceed to step 5 until the measurement is completed.

[0037] Step 6: The detection operation is completed and the system is powered off.

[0038] Therefore, the present invention has the following advantages:

[0039] 1) The present invention is a non-contact measurement and will not damage the structure of the tunnel lining and other auxiliary equipment on the tunnel surface;

[0040] 2) The present invention uses laser shock waves to give an initial force to the surface of the tunnel lining. Compared with manual knocking and hammering, the force and range of vibration can be controlled more accurately, the force of each impact can be accurately quantified according to needs, and the impact frequency can be controlled automatically, which greatly improves the speed of detection operations.

[0041] 3) Compared with the method of relying on human ears to listen to the echo and arranging acceleration sensors after knocking, the present invention uses a laser Doppler vibrometer to measure the vibration of the tunnel lining surface, which can accurately measure the subtle changes in the vibration frequency of the lining surface with internal voids.

[0042] 4) With the mileage encoder, it can automatically record the exact mileage at which the air gap disease occurred, which is convenient for subsequent digital management.

[0043] 5) There is no need to lay out the test line in advance during the test, which greatly speeds up the test work and can achieve a measurement speed of 5-15km / h;

[0044] 6) According to the strength of the feedback vibration frequency, the area of ​​the void defect can be estimated; specifically, the vibration meter measures the vibration frequency of the tunnel surface, and the energy spectrum and frequency spectrum of the vibration are obtained through Fourier transform. According to the size of the energy wave peak and the position of the peak caused by the void in the frequency spectrum, the corresponding relationship between the size of the void area and the strength of the vibration frequency is established to achieve the estimation of the void area.

[0045] 7) In addition to detecting the hollowing defects inside the tunnel lining, it can also detect the internal stress state of the tunnel lining and discover the severity and specific location of the uneven force in the tunnel in advance; when stress concentration occurs in the tunnel lining, the local oscillation frequency of the tunnel will change. Even if the tunnel is not hollowed out, the lining is squeezed by external force and stress concentration occurs. The vibration frequency measured by the vibration meter will change slightly. The stress concentration of the tunnel can be determined through spectrum transformation analysis.

[0046] 8) By cooperating with the laser ranging sensor, servo motor and servo platform, it is ensured that the laser Doppler vibrometer optical head and the lining surface are always at the optimal working distance, solving the problem that the uneven lining surface affects the vibrometer measurement focal length. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is the overall composition of the system of the present invention;

[0048] Figure 2 The installation angle of the optical head of the laser Doppler vibrometer of the present invention;

[0049] Figure 3 is the impact angle of the laser shock wave of the present invention;

[0050] Figure 4It is a schematic diagram of the internal connection components of the tunnel lining internal void rapid detection system of the present invention;

[0051] Figure 5 A system synchronization solution of the present invention;

[0052] Figure 6 A distribution diagram of the servo platform and measurement sensors of the present invention;

[0053] Figure 7 It is a front view of the overall structure of the device of the present invention;

[0054] Figure 8 The overall structure of the device of the present invention is shown in the right side view

[0055] Fig. 9 is a detection flow chart of an embodiment of the present invention;

[0056] Fig.10 A schematic diagram of a single track detection solution according to an embodiment of the present invention;

[0057] Fig.11 The optical head measures the angle of the first dual-track detection scheme of the embodiment of the present invention;

[0058] Fig.12 The shock wave impact angle of the first dual-track detection scheme of the embodiment of the present invention;

[0059] Fig.13 The optical head measures the angle of the second dual-track detection scheme according to the embodiment of the present invention;

[0060] Fig.14 The shock wave impact angle of the second dual-track detection scheme of the embodiment of the present invention;

[0061] Fig.15 A schematic diagram of a dual-track detection solution according to an embodiment of the present invention;

[0062] Fig.16 It is a schematic diagram of the structure of the trolley of the present invention.

[0063] In the figure: it includes a laser Doppler vibrometer optical head 1; a laser ranging sensor 2; a servo mobile platform 3; a servo motor 4; an inertial navigation unit 5; a host computer 6; a data synchronization control acquisition module 7; a tunnel detection trolley 8; a mileage encoder 9; a ring bracket 10; a lifting platform 11; a high-energy pulse laser transmitter 12; a rotating mirror 13; and a frameless motor 14. DETAILED DESCRIPTION

[0064] In order to further understand the content of the present invention and make the purpose, technical solution and advantages of the present invention clearer, the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that this is only an explanation of the present invention and not a limitation.

[0065] Among the methods for detecting voids inside tunnel lining concrete, the coring method is not only highly destructive, but also unable to conduct a comprehensive inspection of the tunnel; although the ground penetrating radar method is more comprehensive, it is limited by its detection principle and has poor detection effect on tunnel linings covered with dense steel mesh, and is prone to false detection and missed detection; although the manual detection method is simple, it has low operating efficiency and is also prone to false detection and missed detection, and has a low degree of digitization.

[0066] The present invention designs a tunnel lining structure internal void disease detection device based on the laser impact method, such as Figure 1 As shown, it includes hardware parts and corresponding data receiving and processing modules. The hardware mainly includes: measuring equipment, tunnel detection vehicle 8, data synchronization control acquisition module 7 and host computer 6. The measuring equipment mainly includes inertial navigation unit 5, laser ranging sensor 2, laser Doppler vibrometer, high-energy pulse laser transmitter 12 and mileage encoder 9; the data synchronization control acquisition module 7 receives and synchronously processes the data collected by the inertial navigation unit 5, laser ranging sensor 2, laser Doppler vibrometer, high-energy pulse laser transmitter 12 and mileage encoder 9, and communicates with the host computer (data transmission); the host computer collects and saves the uploaded data, pre-processes (time-frequency domain conversion, filtering, smoothing, error model correction), displays in real time, alarms, and performs post-precision processing.

[0067] Core sensor layout scheme, such as Figure 2 As shown: the laser Doppler vibrometer is installed at a fixed angle in the same vertical plane, and the measuring optical heads 1 of the Doppler vibrometer are installed at 0°, 30°, 60°, 90°120°, 150° and 180°, numbered 1-7 respectively. Theoretically, the more measuring optical heads 1 of the Doppler vibrometer are arranged, the better, because the distance to the void position is random, and the angle of the void position is not known in advance. However, if the tunnel is voided, after the shock wave hits the tunnel wall, the vibration caused by the void will cause vibration in a certain area, and it is sufficient to measure the vibration in this area. Therefore, arranging too many and too dense optical heads of the vibrometer will cause waste. The price of a single optical head is hundreds of thousands, and the cost needs to be considered. Therefore, it is sufficient to ensure that the interval between the optical heads is less than or equal to 30°. The design of 7 measuring optical heads in the present invention not only meets the measurement requirements but also saves costs. The high-energy pulse laser transmitter emits a high-power short-pulse laser at a fixed angle in the vertical plane to impact the surface of the tunnel wall in a rotating mirror scanning manner. The impact position is as follows Figure 3As shown, within the angle range of 0°-180°, the interval between the impact positions is 7.5°, and there are 25 impact positions in total. Under the above layout scheme, the high-energy pulse laser emitter scans the tunnel cross-section counterclockwise to complete the impact on the tunnel wall surface within the range of 180°. The 7 Doppler vibrometer optical heads are evenly distributed in the 180° circular plane, among which the measurement optical head of Doppler vibrometer No. 1 corresponds to the 0° position, and the measurement optical head of Doppler vibrometer No. 7 corresponds to the 180° position, and the vibration frequency of the tunnel surface is collected at the same time. Among them, the impact plane of the laser impact is in front, and the measurement plane of the Doppler vibrometer optical head is in the back. First, the laser impact emits a high-energy pulse laser to bombard the tunnel surface, causing vibration; the measurement plane is in the back, and the vibration of the tunnel surface is measured after the high-energy pulse laser is emitted.

[0068] The system internal connection composition scheme, such as Figure 4 As shown: the main measuring sensors, laser Doppler vibrometer, inertial navigation unit, laser ranging sensor, encoder and high-energy pulse laser transmitter are connected to the multi-source sensor data synchronization acquisition card through the RS422 interface. Among them, the 7-channel RS422 interface of the laser Doppler vibrometer corresponds to 7 optical lenses respectively, and the single channel is controlled. Each optical head can independently complete the acquisition of observation data. The acquisition time is uniformly controlled by the multi-source data synchronization acquisition card to ensure that even if one of the optical heads cannot work normally, the remaining optical heads can still collect data normally and transmit it back; the high-energy pulse laser transmitter is connected to the multi-source data synchronization acquisition card through the RS422 interface, and the emission time is controlled by the multi-source data synchronization acquisition card Unified control; the inertial navigation unit is connected to the multi-source data synchronization acquisition card through the RS422 interface, receives the trigger acquisition signal of the multi-source data synchronization acquisition card, collects the attitude data and returns it to the acquisition card; the encoder continuously collects data, the acquisition card sends out a synchronous acquisition signal, and receives the data sent back by the encoder; the laser ranging sensor is connected to the multi-source data synchronization acquisition card through the RS422 interface, receives the trigger acquisition signal of the multi-source data synchronization acquisition card, collects the distance between the lens and the tunnel lining surface and returns it to the acquisition card; the servo motor is connected to the multi-source data synchronization acquisition card through the serial port, receives the forward or reverse command and executes it, ensuring that the distance between the optical head of the laser Doppler vibrometer and the lining surface is the set value during measurement.

[0069] The acquisition frequency of the above sensors is uniformly controlled and executed by a multi-source data synchronization acquisition card at a fixed frequency. Each packet of measured data is time-stamped and uploaded to the host computer. There is no need for post-processing software time alignment. Time alignment is completed directly during data acquisition, with high synchronization accuracy.

[0070] Synchronization scheme of multi-source sensors and synchronous acquisition cards, such as Figure 5As shown in the figure: the multi-source data synchronization acquisition card actively sends synchronization signals to the high-energy pulse laser transmitter, laser Doppler vibrometer optical head, inertial navigation device, laser ranging sensor and encoder at a certain interval. After the above sensors receive the synchronization signal, the high-energy pulse laser transmitter immediately emits a laser shock wave to impact the lining surface; the laser Doppler vibrometer optical head then collects the vibration frequency of the tunnel lining surface and returns it to the multi-source data synchronization acquisition card; the inertial navigation device simultaneously returns the current attitude angle (heading angle, pitch angle and roll angle), the encoder simultaneously returns the speed value measured at the current moment, and the laser ranging sensor returns the current distance measurement value; the acquisition card obtains the distance from the laser Doppler vibrometer optical head to the tunnel lining surface and compares it with the set value, and then sends a control signal to the servo motor. The servo motor controls the extension and retraction of the laser Doppler vibrometer optical head by forward and reverse rotation to keep the distance from the tunnel lining surface at the set value.

[0071] The overall structure diagram of the testing equipment, such as Figure 6 , 7 As shown in Figure 8, the tunnel inspection vehicle has two seats. Only two people are needed for each operation, one to drive the vehicle normally and one to manage the normal operation of the air escape rapid detection system. Figure 2 The distribution scheme is arranged, and some measuring sensors are installed on the lifting platform at the rear of the tunnel inspection trolley. When inspecting different types of tunnels, the height of the system can be adjusted so that the laser Doppler vibrometer optical head at 0° is aligned with the intersection of the ground and the tunnel side wall, i.e., the arch foot, and then the inspection work can be started. Among them, 1 laser Doppler vibrometer optical head and 2 laser distance sensor are installed on 3 servo mobile platforms. The laser Doppler vibrometer optical head is fixedly installed at the center of the servo mobile platform, and the laser distance sensor is installed on the side of the same platform, and its own angle can be adjusted. Each vibrometer laser head is equipped with a laser distance meter. Since the vibrometer needs to maintain its distance from the tunnel wall when working, but there may be convexities or depressions on the tunnel lining surface, the distance meter measures that the distance between the vibrometer and the tunnel lining surface has changed, and the acquisition card will issue corresponding instructions to control the forward and reverse rotation of the servo motor, and then control the servo platform 3 to shrink or extend, so as to keep the distance between the vibrometer optical head 1 and the tunnel lining constant. The laser emission point of the laser distance sensor lens plane and the laser emission point of the laser Doppler vibrometer optical head lens plane are in the same plane; the high-energy pulse laser emitter 12 is installed in the middle of the tunnel detection vehicle 8, and the emitted high-energy pulse laser can be refracted by the rotating mirror 13 to achieve 180° scanning operation, and the rotation of the rotating mirror 13 is driven by the frameless motor 14. The ring bracket 10 is installed at the center of the lifting platform 11, and the inertial navigation unit 5 is installed directly below the center of the lifting platform 11, and also directly below the intersection of the reverse extension line of the Doppler vibrometer optical head installation, so as to measure the attitude change of the air escape detection system in real time.

[0072] The technical solution of the present invention is further described in detail below through examples and in conjunction with the accompanying drawings. Fig. 9 As shown:

[0073] After the detection work begins, step 1: the system is powered on for self-test, and the power is turned on to supply power to 1 laser Doppler vibrometer optical head, 2 laser ranging sensor, 4 servo motor, 5 inertial navigation unit, 6 host computer, 9 mileage encoder, 7 data synchronization control acquisition module, 12 high-energy pulse laser transmitter and 14 frameless motor to ensure that all sensors and modules can work normally;

[0074] Step 2: At a location where the tunnel lining surface is flat, turn on 1 laser Doppler vibrometer optical head and 2 laser distance measuring sensors. 1 laser Doppler vibrometer optical head emits laser and forms a light spot on the tunnel lining surface, and 2 laser distance measuring sensors emit ranging laser and form a light spot on the tunnel lining surface. Among them, the distance L measured by 2 laser distance measuring sensors can be used to obtain the distance between 1 laser Doppler vibrometer optical head and the tunnel lining surface. 7 data synchronization control acquisition module will record this value and set it as the standard value, completing the calibration of the distance measured by the laser Doppler vibrometer optical head;

[0075] Step 3: Adjust the lifting platform 11 to the appropriate position, that is, the optical head of the No. 1 laser Doppler vibrometer at a 0° angle or the optical head of the No. 7 laser Doppler vibrometer at a 180° angle is aligned with the arch foot and flush with the arch foot. The reason is that the heights of the arch feet of different types of tunnels are different, such as the positions of the arch feet of subways, high-speed railways and highways;

[0076] This embodiment uses 7 optical heads of laser Doppler vibrometers to achieve full coverage of the tunnel section while minimizing costs. In theory, the more measuring optical heads of Doppler vibrometers are arranged, the better, because the distance to the void is random, and the angle of the void is not known in advance. The price of a single optical head is hundreds of thousands, and the cost needs to be considered. This design study takes into account that after the shock wave hits the tunnel wall, the vibration caused by the void will cause vibration in a certain area, and it is sufficient to measure the vibration in this area. Therefore, 7 measuring optical heads are designed to cover the tunnel section of 0-180 degrees as much as possible, with an interval of 30° between them. It can detect most void diseases. The interval is less than or equal to 30°.

[0077] Step 4: Control the 8 tunnel inspection vehicle to start running from the tunnel entrance, with a running speed range of 5-15km / h;

[0078] Step 5: The measuring equipment starts working. A complete measurement process includes two parts: optical head measurement focus adjustment and vibration frequency measurement. The first step is to adjust the measurement focus. The 7 data synchronization control acquisition module sends a synchronization acquisition signal to the 2 laser ranging sensors to measure whether the distance between the current tunnel lining surface and the 1 laser Doppler vibrometer optical head is the set standard value. If it is the set standard value after comparison, the next step of vibration frequency measurement is performed. The specific workflow of vibration frequency measurement is that the 7 data synchronization control acquisition module sends a synchronization signal to the 1 laser Doppler vibrometer optical head, 12 high-energy pulse laser transmitter, 5 inertial navigation unit, 6 host computer, and 9 mileage encoder. After receiving the synchronous acquisition signal, 12 high-energy pulse laser transmitters emit high-energy pulse lasers to 13 galvanometer mirrors, which act on the surface of the tunnel lining after rotational refraction and induce micro-vibration of the lining. Subsequently, 1 laser Doppler vibrometer optical head, 5 inertial navigation units and 9 mileage encoders respectively collect measurement data at the same time. The collected measurement data are transmitted back to 7 data synchronous control acquisition module, and then uploaded to 6 host computer by 7 data synchronous control acquisition module.

[0079] If it is not the set standard value after comparison, the 7 data synchronization control acquisition module will compare the actual measurement value returned by the 2 laser ranging sensors with the preset standard value, and send a control signal to the 4 servo motor to rotate forward or reverse, indirectly controlling the extension and contraction of the 3 servo mobile platform. That is, if the actual measurement value returned by the 2 laser ranging sensors is less than the preset standard value, the 4 servo motors are controlled to rotate forward, and the 3 servo mobile platform shrinks inward until the actual measurement value returned by the 2 laser ranging sensors is equal to the preset standard value. If the actual measurement value returned by the 2 laser ranging sensors is greater than the preset standard value, the 4 servo motors are controlled to rotate reversely, and the 3 servo mobile platform stretches outward until the actual measurement value returned by the 2 laser ranging sensors is equal to the preset value. This process continues until the actual measurement value returned by the 2 laser ranging sensors is equal to the preset standard value. At this time, the vibration frequency measurement can be performed to complete a complete measurement process. With the operation of the 8 tunnel detection trolley, the measurement process of step 5 will continue until the measurement is completed.

[0080] Step 6: The detection operation is completed and the system is powered off.

[0081] In the actual implementation process, due to the measurement range of 1 laser Doppler vibrometer optical head and the range limitations of 12 high-energy pulse laser emitters, the detection schemes are divided into single-track detection scheme and double-track detection scheme for both single-track and double-track tunnel types.

[0082] like Fig.10As shown in Figure 1, the single track detection scheme is suitable for single track tunnels with small and medium spans, such as subway tunnels and single track high-speed railway tunnels. Figure 2 The laser Doppler vibrometer optical head installation angle and Figure 3 The laser shock wave impact angle is detected, wherein the Doppler vibrometer optical heads 1-7 are all turned on and the high-energy pulse laser transmitter is based on Figure 3 The angle shown, that is, from 0° to 180°, is used to impact the lining surface with high-energy lasers. The tunnel inspection trolley can complete a comprehensive inspection of the tunnel by running along the tunnel once.

[0083] The dual-track detection scheme is suitable for large high-speed railway tunnels with dual tracks. The overall structural size of this type of tunnel is large, and the span of the left and right side walls exceeds 15m. The single-track detection scheme cannot take into account the side walls on both sides at the same time. In order to ensure the comprehensive detection and detection accuracy of the tunnel, the dual-track detection scheme is adopted. The dual-track detection scheme is divided into two measurements, namely, first controlling the tunnel detection trolley to run along the single-side track, such as Fig.11 and 12 As shown, the Doppler vibrometer optical head 1-5 is controlled to start operation, and the laser shock wave impact angle ranges from 0° to 127.5°; after the first detection is completed, the tunnel detection trolley is moved to the opposite track for the second detection, as shown in FIG. Fig.13 and 14 As shown, during the second detection process, the Doppler vibrometer optical head 3-7 is controlled to start operation, and the laser shock wave impact angle is from 52.5° to 180°. Fig.15 As shown, the two tests will partially overlap at the vault, ensuring a complete test of the entire tunnel section.

[0084] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0085] Although this article uses more frequently: 1 laser Doppler vibrometer optical head; 2 laser ranging sensor; 3 servo mobile platform; 4 servo motor; 5 inertial navigation unit; 6 host computer; 7 data synchronization control acquisition module; 8 tunnel detection vehicle; 9 mileage encoder; 10 ring bracket; 11 lifting platform; 12 high energy pulse laser transmitter 13 rotating mirror; 14 frameless motor, it does not exclude the possibility of using other terms. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

[0086] The present invention proposes to use a high-power short-pulse high-energy pulse laser transmitter to generate a laser shock wave to generate an instantaneous force on the surface of the tunnel lining. Then, a laser Doppler vibrometer measures the vibration generated on the surface of the tunnel lining after the force is applied and records the vibration frequency. Through time-frequency domain conversion, various noise frequencies mixed in the result are removed, and subtle changes in the vibration frequency are analyzed. Once a hollow disease is found, the mileage of the disease is immediately recorded and an alarm is sounded, thereby completing the rapid detection of hollows inside the tunnel lining. Laser shock waves use high-power short-pulse lasers to irradiate target materials. The surface of the material quickly absorbs laser energy, explosively vaporizes, and ionizes to generate high-temperature and high-pressure plasma. The temperature rises sharply, and the plasma expands sharply, thereby generating a high-pressure shock wave on the surface or inside the material. Laser shock wave technology has the advantages of small heat-affected area, high pressure, superposition, non-contact, and easy and precise positioning and control.

Claims

1. A tunnel lining structure internal void disease detection equipment based on laser impact method, characterized by: It includes a measuring device, a data synchronization control acquisition module and a host computer. The measuring device includes an inertial navigation unit, a laser ranging sensor, a laser Doppler vibrometer, a high-energy pulse laser transmitter and a mileage encoder; the data synchronization control acquisition module receives and synchronously processes the data collected by the measuring device and communicates with the host computer; the host computer collects and saves the uploaded data, pre-processes, displays in real time, alarms, and performs post-precision processing; There are multiple laser Doppler vibrometers installed on the semicircular surface of the same vertical plane at the same interval angle, and there are multiple laser distance measuring sensors installed corresponding to the laser Doppler vibrometers; the high-energy pulse laser emitter scans the tunnel cross section at a certain angle within the required angle range by means of rotating mirror scanning; the impact plane of the laser impact is in front, and the measurement plane of the laser Doppler vibrometer optical head is in the back; the laser Doppler vibrometer and the laser distance measuring sensor are installed on the same servo moving platform to ensure that the distance between the laser Doppler vibrometer optical head and the lining surface is the set value during measurement, and the angle of the laser distance measuring sensor itself can be adjusted; the laser emission point of the laser distance measuring sensor lens plane and the laser emission point of the laser Doppler vibrometer optical head lens plane are in the same plane; The laser Doppler vibrometer, inertial navigation unit, laser ranging sensor, encoder and high-energy pulse laser transmitter are all connected to the multi-source sensor data synchronization acquisition card through the RS422 interface, wherein the multi-channel RS422 interfaces of the laser Doppler vibrometer are respectively connected to the optical lenses, and the single channel corresponds to the control; the multi-source sensor data synchronization acquisition card is connected to the host computer.

2. According to claim 1, the tunnel lining structure internal void disease detection equipment based on the laser impact method is characterized by: Then, 7 laser Doppler vibrometers are provided, with an interval of 30°.

3. According to claim 1, the tunnel lining structure internal void disease detection equipment based on the laser impact method is characterized by: The high-energy pulse laser transmitter scans at an angle interval of 7.5° and has 25 impact positions.

4. According to claim 1, the tunnel lining structure internal void disease detection equipment based on the laser impact method is characterized by: The laser Doppler vibrometer optical head is fixedly installed at the center of the servo platform, and the laser distance measuring sensor is installed on the side of the same platform.

5. A tunnel lining structure internal void disease detection vehicle based on a laser impact method, comprising a vehicle body, characterized in that: The trolley body is equipped with a tunnel lining structure internal void disease detection equipment based on the laser impact method as described in any one of claims 1 to 4, and the trolley body is provided with two seats and a lifting platform; the laser Doppler vibrometer is installed on a semi-circular bracket at the same interval angle; the high-energy pulse laser emitter is installed in the middle of the trolley body, and realizes 180° scanning operation through refraction, and the rotation of the rotating mirror is driven by a frameless motor; the inertial navigation unit is installed directly below the center of the lifting platform, and is also directly below the intersection of the reverse extension line of the optical head installation of the laser Doppler vibrometer.

6. A method for detecting small and medium span tunnels using the tunnel lining structure internal void disease detection equipment based on the laser impact method according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Power on the system and perform self-test to ensure that all sensors and modules can work normally; Step 2: At a location where the tunnel lining surface is flat, turn on the laser Doppler vibrometer optical head and the laser distance sensor, and use the laser distance sensor to calibrate the distance measured by the laser Doppler vibrometer optical head; Step 3: Adjust the position of the laser Doppler vibrometer to ensure that the optical heads of the first and last laser Doppler vibrometers are aligned with the tunnel arch foot and are flush with the arch foot; Step 4: Control the tunnel lining structure internal void disease detection equipment based on the laser impact method to start running from the tunnel entrance, with a running speed range of 5-15km / h; Step 5: When the measuring equipment starts working, the first thing to do is to adjust the measurement focal length. The data synchronization control acquisition module sends a synchronization acquisition signal to the laser ranging sensor to measure whether the distance between the current tunnel lining surface and the laser Doppler vibrometer optical head is the set standard value. If it is the set standard value after comparison, the next step of vibration frequency measurement is performed; the specific workflow of vibration frequency measurement is that the data synchronization control acquisition module sends a synchronization signal to the laser Doppler vibrometer optical head, high-energy pulse laser transmitter, inertial navigation unit, host computer, and mileage encoder; after receiving the synchronization acquisition signal, the high-energy pulse laser transmitter emits a high-energy pulse laser to the galvanometer. Light, after rotation and refraction, acts on the surface of the tunnel lining and causes the lining to produce micro-vibration. Subsequently, the laser Doppler vibrometer optical head, inertial navigation unit and mileage encoder respectively collect measurement data at the same time, and the collected measurement data are transmitted back to the data synchronization control acquisition module, and then uploaded to the host computer by the data synchronization control acquisition module; after comparison, if it is not the set standard value, the position of the laser ranging sensor is adjusted so that the actual measurement value returned by it is equal to the pre-set standard value; at this time, the vibration frequency is measured to complete a complete measurement process; with the operation of the tunnel detection vehicle, the measurement process of step five will continue until the measurement is completed; Step 6: The detection operation is completed and the system is powered off.

7. A method for detecting large-span tunnels using the tunnel lining structure internal void disease detection equipment based on the laser impact method according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Power on the system and perform self-test to ensure that all sensors and modules can work normally; Step 2: At a location where the tunnel lining surface is flat, turn on the laser Doppler vibrometer optical head and the laser distance sensor, and use the laser distance sensor to calibrate the distance measured by the laser Doppler vibrometer optical head; Step 3: Turn on the laser Doppler vibrometer at the corresponding position, and ensure that the first optical head is aligned with the arch foot on one side of the tunnel and is flush with the arch foot; the last laser Doppler vibrometer is the one closest to the first optical head at an angle of 127.5°; Step 4: Control the tunnel lining structure internal void disease detection equipment based on the laser impact method to start running from the tunnel entrance, with a running speed range of 5-15km / h; Step 5: When the measuring equipment starts working, the first thing to do is to adjust the measurement focal length. The data synchronization control acquisition module sends a synchronization acquisition signal to the laser ranging sensor to measure whether the distance between the current tunnel lining surface and the laser Doppler vibrometer optical head is the set standard value. If it is the set standard value after comparison, the next step of vibration frequency measurement is performed; the specific workflow of vibration frequency measurement is that the data synchronization control acquisition module sends a synchronization signal to the laser Doppler vibrometer optical head, high-energy pulse laser transmitter, inertial navigation unit, host computer, and mileage encoder; after receiving the synchronization acquisition signal, the high-energy pulse laser transmitter emits a high-energy pulse to the galvanometer. The energy pulse laser acts on the surface of the tunnel lining after rotation and refraction, causing the lining to produce micro-vibration. Subsequently, the laser Doppler vibrometer optical head, inertial navigation unit and mileage encoder respectively collect measurement data at the same time, and the collected measurement data are transmitted back to the data synchronization control acquisition module, and then uploaded to the host computer by the data synchronization control acquisition module; after comparison, if it is not the set standard value, the position of the laser ranging sensor is adjusted so that the actual measurement value returned by it is equal to the pre-set standard value; at this time, the vibration frequency is measured to complete a complete measurement process; with the operation of the tunnel inspection vehicle, the measurement process of step five will continue; Step 6: After completing the inspection on one side of the tunnel, move the equipment to the other side of the tunnel and turn on the laser Doppler vibrometer at the corresponding position, the first one is close to 52.5° horizontal angle, and the last one is 180°; then proceed to step 5 until the measurement is completed; Step 7: After the detection is completed, the system is powered off.

Images