A device for detecting water accumulation in a boom head of a tied arch bridge

Abstract

The application provides a kind of for tied arch bridge suspender head ponding detection device, detection device includes: annular component and main body structure;The main body structure includes nuclear magnetic signal emission module, nuclear magnetic signal receiving module, power supply module and data processing module;Nuclear magnetic signal emission module includes radio frequency coil and nuclear magnetic signal transmitter;The radio frequency coil is coaxially arranged in the annular component, and the nuclear magnetic signal transmitter is electrically connected with the radio frequency coil circuit;The nuclear magnetic signal receiving module includes inductive coil and nuclear magnetic signal collector;The inductive coil is coaxially arranged in the annular component;The nuclear magnetic signal collector is electrically connected with the data processing module, and the data processing module is used to obtain NMR data according to nuclear magnetic resonance echo signal, and based on NMR data, the ponding state in the region to be measured is identified.The detection device in the application can not damage the original structure of anchor head protective cover during detection, to improve the convenience of detection.

Description

Technical Field

[0001] This invention relates to the field of tied-arch bridge inspection technology, and more particularly to a device for detecting water accumulation at the suspender heads of tied-arch bridges. Background Technology

[0002] Tied-arch bridges, as a type of bridge structure with low foundation requirements, high span capacity, and aesthetically pleasing appearance, are widely used in highway, municipal, and river-crossing projects. In tied-arch bridges, the hangers are the core tension members connecting the arch ribs and the bridge deck, and their working condition directly affects the stability of the overall bridge structure. When the hanger anchor head casing becomes damp or leaks due to factors such as poor sealing or a humid environment, water easily accumulates inside the casing, leading to problems such as corrosion of the hanger wires and loosening of the wire bundles. This further increases the risk of broken wires, fractures, and detachment of the steel strand clamps, seriously endangering the operational safety of the bridge. Therefore, to extend the service life of the hangers and ensure bridge safety, it is necessary to conduct timely special inspections and maintenance protection of the hanger anchor heads.

[0003] Currently, the conventional method for inspecting bridge suspender anchor heads involves using specialized tools to chisel away the sealing concrete or cut the sealing steel plate to expose the anchor head. After inspection, the anchor head is then resealed with concrete or the sealing steel plate is welded back to its original state. This inspection method not only requires significant manpower, financial resources, and time, resulting in low construction efficiency, but also, due to construction difficulty and cost limitations, makes it difficult to conduct regular comprehensive inspections of all anchor heads across the entire bridge for seepage, water accumulation, and corrosion. Therefore, it fails to meet the practical needs of long-term health monitoring of bridge suspenders.

[0004] Therefore, it is necessary to develop a device that can perform non-destructive testing of water accumulation and corrosion inside the anchor head casing without damaging or disassembling the original structure. This device overcomes the shortcomings of existing testing methods and has significant engineering practical value and promotional significance. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a device for detecting water accumulation at the head of a tie-arch bridge, the device comprising: an annular assembly, the annular assembly being coaxially fitted onto the outside of the anchor head protective cover of the tie-arch bridge, such that the central region of the annular assembly corresponds to the test area of ​​water accumulation inside the anchor head protective cover; a main structure, the main structure comprising a nuclear magnetic resonance (NMR) signal transmitting module, a NMR signal receiving module, a power supply module, and a data processing module; wherein, the NMR signal transmitting module comprises a radio frequency coil and an NMR signal transmitter; the power supply module is circuitically connected to the NMR signal transmitter, enabling the NMR signal transmitter to output radio frequency excitation pulses at the Ramohr frequency; the radio frequency coil is coaxially disposed on the tie-arch bridge. Inside the annular assembly, the NMR signal transmitter is connected to the radio frequency coil circuit, so that in the transmission state, the NMR signal transmitting module can transmit radio frequency excitation pulses to the water accumulation test area through the radio frequency coil; the NMR signal receiving module includes an induction coil and an NMR signal acquisition device; the induction coil is coaxially disposed inside the annular assembly, and the induction coil is connected to the NMR signal acquisition device circuit, for receiving the NMR echo signal generated by proton relaxation inside the test area; the NMR signal acquisition device is connected to the data processing module circuit, and the data processing module is used to obtain NMR data based on the NMR echo signal, and identify the water accumulation state in the test area based on the NMR data.

[0006] In some embodiments of the present invention, the radio frequency coil and the induction coil are configured as a wound coil group, and the nuclear magnetic resonance (NMR) signal transmitter and the NMR signal collector are connected to the coil group circuit through a selection control circuit; the selection control circuit is configured such that, in the transmission state, the NMR signal collector is disconnected from the coil group circuit, and the NMR signal transmitter is connected to the coil group circuit; in the reception state, the NMR signal transmitter is disconnected from the coil group circuit, and the NMR signal collector is connected to the coil group circuit.

[0007] In some embodiments of the present invention, the radio frequency coil and the induction coil are configured as two winding coil groups, the radio frequency coil and the induction coil being arranged coaxially; in the radial direction of the annular assembly, the radio frequency coil and the induction coil are nested inside and outside, the radio frequency coil being located outside the induction coil.

[0008] In some embodiments of the present invention, the detection device further includes an adjusting arm assembly, which is wholly or partially C-shaped; the main structure is located on the upper bridge deck of the tied arch bridge, one end of the adjusting arm assembly is connected to the main structure, and the other end is connected to the annular assembly; the main structure and the annular assembly are located on the same side of the adjusting arm assembly, and the middle part of the adjusting arm assembly has a clearance space formed by the bending part of the C-shaped structure to avoid the outer edge structure of the bridge deck in the width direction of the tied arch bridge, so that in the detection state, the annular assembly can move from the upper bridge deck position to the position below the bridge deck corresponding to the area to be tested through the adjusting arm assembly.

[0009] In some embodiments of the present invention, the adjusting arm assembly is provided with a vision module, including a camera and a display screen; the camera is disposed at one end of the adjusting arm assembly that connects to the annular assembly; the display screen is disposed on the main structure and is used to display the spatial relative position of the annular assembly and the anchor head protective cover.

[0010] In some embodiments of the present invention, the adjusting arm assembly includes: a first lateral adjusting mechanism, a vertical adjusting mechanism, a second lateral adjusting mechanism, and a rotation adjusting mechanism; one end of the first lateral adjusting mechanism is fixedly connected to the main structure, and the other end is connected to the upper end of the vertical adjusting mechanism; one end of the second lateral adjusting mechanism is connected to the annular assembly, and the other end is connected to the lower end of the vertical adjusting mechanism; at least one end of the vertical adjusting mechanism is provided with the rotation adjusting mechanism to be rotatably connected to the first lateral adjusting mechanism and / or the second lateral adjusting mechanism.

[0011] In some embodiments of the present invention, the adjusting arm assembly adopts a telescopic sleeve structure or a multi-joint swing arm structure.

[0012] In some embodiments of the present invention, the annular assembly includes a centering adjustment mechanism; the centering adjustment mechanism includes at least three sets of push-pull wheel assemblies; the push-pull wheel assemblies are evenly arranged in the circumferential direction of the annular assembly; each push-pull wheel assembly includes a push-pull wheel, a spring, and a mounting base, the mounting base is fixedly mounted on the annular assembly, the push-pull wheel is connected to the mounting base through the spring, and the push-pull wheel is used to contact and abut against the outer wall of the anchor head protective cover.

[0013] In some embodiments of the present invention, the detection device further includes a magnetic field compensation module, which is provided with a magnetic sensor and a compensation coil. The magnetic sensor is disposed inside the annular assembly and is used to detect the magnetic field distortion signal generated in the test area by the anchor head protective cover or the metal anchor head. The compensation coil is coaxially arranged inside the annular assembly and is located outside the radio frequency coil and the induction coil. The magnetic sensor and the compensation coil are both circuit-connected to the data processing module. The data processing module is used to apply a reverse compensation magnetic field to the test area through the compensation coil according to the magnetic field distortion signal to cancel metal interference.

[0014] In some embodiments of the present invention, the compensation coil is a ring coil group or a saddle-shaped coil group.

[0015] The technical solution described in the embodiment of the present invention for the water accumulation detection device at the suspender head of a tied arch bridge has the following beneficial effects: The detection device of this invention is equipped with a nuclear magnetic resonance (NMR) signal transmitting module and a nuclear magnetic resonance (NMR) signal receiving module. It achieves non-destructive testing of water accumulation inside the anchor head protective cover using NMR technology, without damaging the original structure of the anchor head protective cover. This avoids secondary damage to the gantry structure during testing, significantly reducing manpower, financial resources, and time costs, and improving bridge maintenance efficiency, facilitating regular comprehensive inspections of tied-arch bridges. The device also improves detection accuracy, precisely identifying water accumulation around the anchor head. Furthermore, the device includes a ring assembly that provides a stable mounting carrier for the coils, ensuring that the transmitting and receiving coils are coaxially arranged and stably positioned during testing, thus guaranteeing accuracy. The ring assembly also protects the internal coils, reducing environmental impact on core components and extending the device's lifespan.

[0016] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the description, or may be learned by practice of the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures specifically pointed out in the description and drawings.

[0017] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, are not intended to limit the scope of the invention. The components in the drawings are not drawn to scale but are merely illustrative of the principles of the invention. For ease of illustration and description of certain parts of the invention, corresponding portions in the drawings may be enlarged, i.e., may appear larger relative to other components in an exemplary device actually manufactured according to the invention.

[0019] Figure 1 This is a schematic diagram of the detection device and the tied arch bridge in one embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the overall structure of the detection device in one embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the ring component and the coil in one embodiment of the present invention.

[0022] Figure 4 This is a perspective view of a ring-shaped component structure in one embodiment of the present invention.

[0023] Figure 5 This is a longitudinal cross-sectional view of the annular component and the anchor head protective cover in one embodiment of the present invention.

[0024] Figure 6 for Figure 5 A magnified view of a portion of area A in the middle.

[0025] Figure 7 This is a top view of the ring component in one embodiment of the present invention.

[0026] Figure 8 This is a top view of the ring component in another embodiment of the present invention.

[0027] Figure 9 This is a structural diagram of the compensation coil in one embodiment of the present invention.

[0028] Figure 10 This is a schematic diagram of the detection device on the bridge deck in one embodiment of the present invention.

[0029] Figure 11 The diagram shows the excitation pulse signal and NMR signal waveforms of the detection device in this embodiment of the invention.

[0030] Figure label: 1. Detection device; 11. Ring assembly; 111. Centering adjustment mechanism; 111-1. Push wheel; 111-2. Spring; 111-3. Mounting base; 12. Main structure; 121. NMR signal transmitting module; 121-1. Radio frequency coil; 121-2. NMR signal transmitter; 122. NMR signal receiving module; 122-1. Induction coil; 122-2. NMR signal acquisition device; 123. Power supply module; 124. Data processing module; 13. Adjusting arm assembly; 131. First lateral adjustment mechanism; 132. Vertical adjustment mechanism; 133. Second lateral adjustment mechanism; 134. Rotation adjustment mechanism; 14. Vision module; 141. Camera; 142. Display screen; 15. Magnetic field compensation module; 151. Magnetic sensor; 152. Compensation coil; 2. Anchor head protective cover; 3. Borehole anchor head; 4. Borehole; 5. Bridge plate. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0032] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0033] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0034] It should also be noted that, unless otherwise specified, the term "connection" in this article can refer not only to a direct connection, but also to an indirect connection involving an intermediary.

[0035] In the following description, embodiments of the invention will be illustrated with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar parts, or the same or similar steps.

[0036] To address the problems of existing technologies that require damaging the original structure of the anchor head (hereinafter referred to as the anchor head) or protective cover when detecting water accumulation inside the anchor head protective cover of tied arch bridges, resulting in a labor-intensive, time-consuming, cumbersome, and inefficient testing process, this invention provides a water accumulation detection device for anchor heads of tied arch bridges. When using this device to detect water accumulation inside the anchor head protective cover, the annular component is fitted onto the anchor head protective cover to be tested. Activating the device enables non-destructive testing of the anchor head protective cover. Workers do not need to dismantle or damage the original structure of the anchor head protective cover, thus avoiding damage and simplifying the testing process, which improves the overall testing efficiency. Furthermore, this device can identify moisture in advance and prevent potential corrosion and water accumulation on the anchor head 4, enabling early prevention and risk warning.

[0037] This invention provides a device for detecting water accumulation at the suspender heads of tied-arch bridges, such as... Figure 1 and Figure 2 As shown, the detection device includes an annular component 11, which is coaxially fitted onto the outside of the anchor head protection cover 2 of the boom 4, so that the central area of ​​the annular component 11 corresponds to the area to be tested where water accumulates inside the anchor head protection cover 2. In practical scenarios, the anchor head protection cover 2 installed on tie-rod arch bridges is mostly cylindrical. Adjusting the position of the annular component 11 so that it surrounds the outer wall of the anchor head protection cover 2 allows for 360° detection of the overall structure inside the anchor head protection cover 2, preventing missed detections. The annular component 11 can be configured as a hollow structure, with an outer shell of insulating material and an internal annular cavity for placing a coil for detecting water accumulation or a sensor for installation.

[0038] Main structure 12, such as Figures 1 to 2 As shown, the main structure 12 includes a nuclear magnetic resonance signal transmitting module 121, a nuclear magnetic resonance signal receiving module 122, a power supply module 123, and a data processing module 124.

[0039] The NMR signal transmitting module 121 includes an RF coil 121-1 and an NMR signal transmitter 121-2. The power supply module 123 is circuitically connected to the NMR signal transmitter 121-2, enabling the NMR signal transmitter 121-2 to output RF excitation pulses at a Ramohr frequency. The power supply module 123 can use a rechargeable lithium battery pack to extend the standby time of the detection device during operation and improve ease of use. The RF coil 121-1 is coaxially disposed inside the annular assembly 11, and the NMR signal transmitter 121-2 is circuitically connected to the RF coil 121-1, so that in the transmission state, the NMR signal transmitting module 121 can transmit RF excitation pulses to the water-filled area to be tested through the RF coil 121-1. The NMR signal transmitter 121-2 is equipped with a matching capacitor, a frequency converter, and other components to convert the electrical energy provided by the power supply module 123 into the required RF excitation pulse signal for output. During testing, the nuclear magnetic resonance signal transmitting module 121 sends a high-power positive alternating pulse signal into the interior of the anchor head protective cover 2 through the radio frequency coil 121-1 to generate an excitation magnetic field to excite the hydrogen nuclei in the water inside the protective cover, causing them to produce a nuclear magnetic resonance phenomenon.

[0040] The NMR signal receiving module 122 includes an induction coil 122-1 and an NMR signal acquisition unit 122-2. The induction coil 122-1 is coaxially disposed inside the annular assembly 11. The annular cavity inside the annular assembly 11 can be configured as an inner and outer layered structure to house the induction coil 122-1 and the radio frequency coil 121-1 respectively, achieving physical separation. The induction coil 122-1 is circuit-connected to the NMR signal acquisition unit 122-2 to receive the NMR echo signal generated by proton relaxation within the test area. The NMR signal acquisition unit 122-2 is equipped with a signal amplifier and a filter for preliminary processing of the received NMR echo signal. The NMR signal acquisition unit 122-2 is circuit-connected to the data processing module 124. The data processing module 124 is equipped with a data analyzer to obtain NMR data from the NMR echo signal and to identify the water accumulation state within the test area based on the NMR data. The NMR data includes the attenuated sinusoidal envelope signal (FID) of the NMR echo signal.

[0041] The main component of the water inside the protective cover of the anchor head 3 of the aforementioned tied-arch bridge is water, which contains a large number of hydrogen nuclei. These hydrogen nuclei possess nuclear magnetic moments and are the primary source of nuclear magnetic resonance (NMR) signals. This detection device utilizes low-field NMR technology for non-destructive, non-contact, and specific detection of the water inside the protective cover. First, the device can create a stable and uniform main magnetic field around the protective cover using an internal magnetic field or an ambient background magnetic field. Hydrogen nuclei align along the direction of the main magnetic field, forming a macroscopic magnetization vector. Then, the radio frequency coil 121-1 emits a radio frequency pulse signal to the area under test. When the radio frequency frequency matches the precession frequency of the hydrogen nuclei in the current magnetic field, the hydrogen nuclei undergo NMR absorption, absorbing radio frequency energy, and the magnetic field vector deviates from the direction of the main magnetic field. Next, after the radio frequency pulse stops, the excited hydrogen nuclei cannot maintain a high-energy state and gradually recover to an equilibrium state through a relaxation process, releasing the absorbed energy and radiating it outwards in the form of an alternating electromagnetic field. This alternating electromagnetic field signal is acquired by the induction coil 122-1, forming a detectable nuclear magnetic resonance induction decay signal (FID).

[0042] During the detection process, the area to be tested may contain a stainless steel anchor head protective cover 2, an iron hanger anchor head 3, concrete filling the anchor head protective cover 2, and accumulated water. Since stainless steel, iron, and concrete have extremely low or no hydrogen nuclei, while water has a high hydrogen nuclei content, the relaxation characteristics of water differ greatly from those of stainless steel, iron, and concrete during the detection process. The strong nuclear magnetic resonance response and distinct relaxation time characteristics of liquid water are utilized to achieve water accumulation detection. The data processing module 124 in the device can further determine whether there is water accumulation inside the protective cover by whether a valid nuclear magnetic resonance signal is present (an echo signal indicates the presence of water / an echo signal indicates the absence of water); determine the amount of water accumulation by the magnitude of the nuclear magnetic resonance signal amplitude (a large amplitude indicates high water content / a small amplitude indicates low water content); and determine the state of the water accumulation by the relaxation time of the nuclear magnetic resonance signal (a longer relaxation time indicates significant water accumulation, and a shorter relaxation time indicates insignificant water accumulation). Under the excitation of the alternating magnetic field formed by the alternating current in the radio frequency coil 121-1, if the anchor head protective cover 2 is filled with water, the protective cover needs to be cut open for drainage and rust removal; if the water accumulation inside the anchor head protective cover 2 is below the lower limit, or there is no water accumulation, it does not need to be disassembled. In the above embodiments, the detection device 1 of the present invention is equipped with a nuclear magnetic resonance signal transmitting module 121 and a nuclear magnetic resonance signal receiving module 122. It uses nuclear magnetic resonance (NMR) technology to achieve non-destructive testing of water accumulation inside the anchor head protective cover 2 without damaging the original structure of the anchor head protective cover 2. This avoids secondary damage to the structure of the suspender 4 during the testing process, significantly reducing the manpower, financial resources, and time costs of testing, and improving bridge maintenance efficiency, facilitating regular comprehensive inspections of tied-arch bridges. The detection device also improves detection accuracy, precisely identifying water accumulation around the suspender anchor head 3. Furthermore, the detection device is equipped with a ring assembly 11, which provides a stable mounting carrier for the transmitting and receiving coils, ensuring that the coils are coaxially arranged and fixed in position during testing, thus improving detection accuracy. The ring assembly also protects the internal coils, reducing the impact of the environment on core components and extending the service life of the detection device.

[0043] Furthermore, such as Figure 11 As shown in Figure (a), the excitation pulse emitted by the radio frequency coil is a high-intensity, extremely short-duration radio frequency sinusoidal pulse emitted by the radio frequency coil towards the area to be detected. It is used to excite the hydrogen nuclei of the water in the detection area to generate nuclear magnetic resonance, and its current waveform satisfies: Where i(t) represents the excitation current of the RF coil (corresponding to the emitted RF magnetic field), which varies with time t; I0 ​​represents the amplitude of the excitation pulse (current peak), which determines the magnitude of the RF energy; ω0 is the Larmor angular frequency, which is the resonance frequency of the hydrogen nucleus under the current static magnetic field. Only frequency matching can excite the hydrogen nucleus to resonate; cos represents the standard sinusoidal carrier form, representing the alternating characteristics of the RF pulse.

[0044] Figure (b) shows the NMR signal received by the induction coil. Its waveform is a sinusoidal oscillation with amplitude decaying exponentially with time, which is the core basis for judging water accumulation during the detection process. Its induced electromotive force waveform satisfies: Where e(t) is the induced electromotive force (NMR signal) received by the induction coil, which varies with time t; E0 is the initial amplitude of the signal, which is proportional to the water content (amount of water) in the detection area: the more water there is, the more hydrogen nuclei there are, the larger E0 is, and the stronger the signal is; exp(-t / T2) * T2 is the exponential decay term, describing the decay of the signal amplitude over time. * Apparent transverse relaxation time is a core characteristic parameter of NMR detection, used to distinguish the state of water (free water T2). * Slower signal attenuation; adsorbed water, capillary water (dampness, seepage) T2 * Shorter signals decay quickly; there is no effective attenuation signal in the dry state); sin(ω0t+φ0) is a sinusoidal oscillation term, ω0 is consistent with the Larmor frequency of the excitation pulse, representing the alternating signal of hydrogen nucleus relaxation radiation, and φ0 is the initial phase.

[0045] In some embodiments, both the radio frequency coil 121-1 and the induction coil 122-1 are wound coil group structures. There are multiple ways to set the number of wound coils. The radio frequency coil 121-1 and the induction coil 122-1 can be set as one wound coil group, or they can be set as two independent wound coil groups respectively.

[0046] In Embodiment 1, the radio frequency coil 121-1 and the induction coil 122-1 can be configured as a wound coil group. The nuclear magnetic resonance (NMR) signal transmitter 121-2 and the NMR signal collector 122-2 are connected to the coil group circuit through a selection control circuit. The selection control circuit is configured such that, in the transmission state, the NMR signal collector 122-2 is disconnected from the coil group circuit, and the NMR signal transmitter 121-2 is connected to the coil group circuit; in the reception state, the NMR signal transmitter 121-2 is disconnected from the coil group circuit, and the NMR signal collector 122-2 is connected to the coil group circuit.

[0047] The selected control circuit mainly functions as a circuit switch to prevent the RF coil 121-1 and the induction coil 122-1 from being simultaneously turned on during operation, which would cause mutual interference of magnetic field signals and thus affect the detection data. Using a single wound coil assembly also simplifies the internal structure of the ring assembly 11, which helps to reduce the weight and size of the ring assembly 11.

[0048] In Example 2, as Figure 3As shown, the radio frequency coil 121-1 and the induction coil 122-1 can also be configured as two wound coil groups, with the radio frequency coil 121-1 and the induction coil 122-1 arranged coaxially. In the radial direction of the annular assembly 11, the radio frequency coil 121-1 and the induction coil 122-1 are nested inside and outside, with the radio frequency coil 121-1 located outside the induction coil 122-1. Placing the induction coil 122-1 at the innermost position allows it to be closer to the area under test, which helps reduce detection interference and improve detection accuracy. Setting two independent wound coils allows for independent control of radio frequency excitation and signal sensing, avoiding signal crosstalk and energy leakage, which helps improve the detection signal-to-noise ratio. Using two coils also allows for optimization of coil parameters (number of turns, wire diameter, Q value, etc.) for transmission and reception respectively, resulting in higher transmission efficiency and more sensitive reception, which further enhances the detection capability of weak water accumulation signals.

[0049] In some embodiments, such as Figure 2 As shown, the detection device 1 also includes an adjusting arm assembly 13, which is wholly or partially C-shaped. The main structure 12 is located on the upper surface of the bridge deck 5 of the tied arch bridge. One end of the adjusting arm assembly 13 is connected to the main structure 12, and the other end is connected to the annular assembly 11. The main structure 12 and the annular assembly 11 are located on the same side of the adjusting arm assembly 13. The middle part of the adjusting arm assembly 13 has a clearance space formed by the bending part of the C-shaped structure, which is used to avoid the outer edge structure of the bridge deck in the width direction of the tied arch bridge. This allows the annular assembly 11 to move from the upper bridge deck position to the position below the bridge deck corresponding to the area to be tested through the adjusting arm assembly 13 during the detection state. During the detection process, the operator operates the detection device on the upper surface of the bridge deck 5, which enables convenient and non-destructive detection of key parts (lower anchor head protective cover), thus improving the safety and efficiency of the detection operation.

[0050] During actual testing, due to gravity, water droplets seeping into the hanger 4 accumulate in the lower anchor head area. Once a certain amount is reached, water accumulates inside the lower anchor head protective cover. Therefore, the lower anchor head, being a region prone to water accumulation and corrosion, requires focused inspection and attention. Due to the structural characteristics of tied-arch bridges, the lower anchor head is located below the bridge deck after installation. Therefore, inspecting the lower anchor head protective cover requires personnel to descend below the bridge or use large equipment such as lifts or cranes, which is not only time-consuming and labor-intensive but also poses safety hazards. The adjustable arm assembly 13 of this testing device allows personnel to quickly inspect the anchor head protective cover located below the bridge deck from the bridge plate 5, improving both efficiency and convenience.

[0051] Furthermore, such asFigure 1 As shown, the adjusting arm assembly 13 includes: a first lateral adjusting mechanism 131, a vertical adjusting mechanism 132, a second lateral adjusting mechanism 133, and a rotation adjusting mechanism 134; one end of the first lateral adjusting mechanism 131 is fixedly connected to the main structure 12, and the other end is connected to the upper end of the vertical adjusting mechanism 132; one end of the second lateral adjusting mechanism 133 is connected to the annular assembly 11, and the other end is connected to the lower end of the vertical adjusting mechanism 132; at least one end of the vertical adjusting mechanism 132 is provided with the rotation adjusting mechanism 134, so as to be rotatably connected to the first lateral adjusting mechanism 131 and / or the second lateral adjusting mechanism 133.

[0052] During the process of moving the annular assembly 11 before detection, the first lateral adjustment mechanism 131, the second lateral adjustment mechanism 133, and the vertical adjustment mechanism 132 are initially in a retracted state to reduce the overall volume of the detection device 1 and facilitate storage. Figure 1 and Figure 10 For example, during the adjustment process, the rotation adjustment mechanism 134 first drives the second lateral adjustment mechanism 133 to rotate to a state parallel to the bridge edge; then, it controls the first lateral adjustment mechanism 131 to extend, moving the annular assembly 11 laterally to the outer side of the bridge edge; and it controls the vertical adjustment mechanism 132 to extend, lowering the annular assembly 11 to a position below the bridge surface. Figure 10 As shown, the control rotation adjustment mechanism 134 rotates clockwise to reach a position below the bridge deck, so that the second lateral adjustment mechanism 133 is perpendicular to the bridge edge; the second lateral adjustment mechanism 133 extends so that the annular assembly 11 reaches the periphery of the lower anchor head protective cover; then the spatial position of the annular assembly 11 is finely adjusted by the vision module 14 so that it fits onto the lower anchor head protective cover.

[0053] In some embodiments, the adjusting arm assembly 13 adopts a telescopic sleeve structure or a multi-joint swing arm structure. Multiple telescopic sleeves are combined and installed, allowing adjustment of the spatial position of the annular assembly by lengthening or shortening the sleeve structure. The length of the multi-sleeve section is continuously adjustable, providing a wide range of adaptability and strong versatility for detecting different bridge types. The shortened length after retraction facilitates storage and relocation. The structural segments of the multi-joint swing arm are hinged to each other, allowing adjustment of the spatial position of the annular assembly 11 by adjusting the swing angle of each segment. The multi-joint swing arm offers flexible posture adjustment through multiple joints, adapting to complex field environments. Furthermore, fine-tuning the swing angle of each joint during adjustment improves the concentricity of the annular assembly 11. In practical use, the structural type of the adjusting arm assembly 13 can be selected according to the detection scenario.

[0054] Furthermore, the adjusting arm assembly 13 has an internal wire compartment for accommodating the connecting wires between the main structure 12 and the ring assembly 11. The adjusting arm assembly 13 can protect the internal wires from external impacts that could damage the wiring and prevent circuit failures.

[0055] In some embodiments, such as Figure 1 As shown, the adjusting arm assembly 13 is equipped with a vision module 14, including a camera 141 and a display screen 142. The camera 141 is located at one end of the adjusting arm assembly 13 that connects to the annular assembly 11. The display screen 142 is mounted on the main structure 12 and is used to display the spatial relative position of the annular assembly 11 and the anchor head protective cover 2. The camera 141 and the display screen 142 are electrically connected. Before inspection, the camera 141 collects real-time data on the alignment of the annular assembly 11 and the anchor head protective cover 2 installed on the lower bridge deck. Workers on the bridge deck can adjust the spatial position of the annular assembly 11 under the bridge deck in real time by observing the display screen 142 to align the two positions.

[0056] In some embodiments, such as Figures 5 to 8 As shown, the annular assembly 11 includes a centering adjustment mechanism 111; the centering adjustment mechanism includes at least three sets of push-pull wheel assemblies; the push-pull wheel assemblies are evenly arranged in the circumferential direction of the annular assembly 11; each push-pull wheel assembly includes a push-pull wheel 111-1, a spring 111-2 and a mounting base 111-3, the mounting base 111-3 is fixedly installed on the annular assembly 11, the push-pull wheel 111-1 is connected to the mounting base 111-3 through the spring 111-2, and the push-pull wheel 111-1 is used to contact and abut against the outer wall of the anchor head protective cover 2. In the detection state, the combined forces of the multiple sets of push-pull wheel assemblies on the centering adjustment mechanism 111 automatically cancel each other out, thereby causing the annular assembly 11 to automatically reach the radially concentric position of the anchor head protective cover 2. The annular assembly 11 and the anchor head protective cover 2 are concentrically aligned, which can improve the concentricity between the annular assembly 11 and the anchor head protective cover 2, and also improve the stability of the annular assembly 11 during the detection process, which is beneficial to improving the detection accuracy of nuclear magnetic resonance signals.

[0057] Furthermore, the centering adjustment mechanism 111 can also act as a buffer to prevent the bridge deck from vibrating due to passing vehicles during the testing process, which could cause the annular component 11 and the anchor head protective cover 2 to collide and cause structural damage, thus improving durability and stability.

[0058] In some embodiments, such as Figures 6 to 9As shown, the detection device 1 further includes a magnetic field compensation module 15, which is equipped with a magnetic sensor 151 and a compensation coil 152. The magnetic sensor 151 is disposed inside the annular assembly 11 and is used to detect the magnetic field distortion signal generated in the area to be tested by the anchor head protective cover 2 or the metal anchor head. The magnetic sensor 151 can be a patch type or a probe type sensor. Figure 9 As shown, the compensation coil 152 is coaxially arranged inside the annular assembly 11, and the compensation coil 152 is located around the radio frequency coil 121-1 and the induction coil 122-1; the magnetic sensor 151 and the compensation coil 152 are both circuit-connected to the data processing module 124. The data processing module 124 is used to apply a reverse compensation magnetic field to the area to be measured through the compensation coil 152 according to the magnetic field distortion signal, so as to cancel the metal interference.

[0059] The data processing module 124 internally stores the ideal uniform static magnetic field B0(t) required for nuclear magnetic resonance, serving as a reference (a uniformly distributed, oriented magnetic field with a waveform that is a straight line under rational conditions without interference from metallic components). The magnetic field compensation process includes the following steps: The magnetic sensor 151 collects the actual magnetic field after it has been disturbed by the metal, i.e., the distorted magnetic field B, in real time. m (t) Its waveform is no longer a straight line; the waveform drifts slowly or fluctuates up and down.

[0060] The calculation and data processing module calculates based on the actual distorted magnetic field B. m The difference between the magnetic field B0(t) and the ideal uniform static magnetic field B0(t) is used to calculate the magnetic field deviation ΔB(t), which is the abnormal interference caused by the metal. Its expression is: The output of the detection device 1 is a reverse compensation magnetic field B, which is equal in magnitude and opposite in direction to the magnetic field deviation, output through the compensation coil 152. c (t), whose expression is: In magnetic field compensation, the compensated uniform magnetic field is approximately equal to the rational static magnetic field, in order to eliminate the magnetic field distortion caused by the metal. Its expression is: In actual testing, most existing anchor head protective covers 2 are made of stainless steel or other metal materials to ensure durability. However, metal materials can interfere with and affect the magnetic field signal during nuclear magnetic resonance (NMR) testing, leading to distorted measurement results. The magnetic field compensation module 15 can detect the magnetic field distortion signal generated by the metal inside the test area. Simultaneously, it outputs a reverse compensation magnetic field through a compensation coil to actively cancel the interference of the metal on the detection magnetic field, thereby achieving accurate detection of water accumulation inside the metal protective cover.

[0061] It is understandable that the blocking effect of metal components on magnetic fields does not completely block the magnetic field from penetrating. Rather, because the magnetic permeability of metal is much higher than that of air, it will concentrate the magnetic field lines inside itself, causing the magnetic field distribution outside the metal to be distorted. There is no complete blockage like electromagnetic shielding. Metal components only change the spatial distribution of the magnetic field, and will not completely prevent the magnetic sensor from receiving signals. The core signal detected by the magnetic sensor is the distorted magnetic field.

[0062] Furthermore, this detection device can also detect moisture contained in the steel cable inside the boom 4. The magnetic field compensation module 15 further counteracts the interference of the metal anchor head on the detection magnetic field, accurately identifying small amounts of moisture in the boom's steel cable. At the lower anchor head of the boom, water droplets leaking from above easily seep into the steel cable inside the boom. When the amount of seeping water is small, the droplets adhere directly to the steel cable and do not flow downwards. In this case, the humid environment created by the water droplets on the steel cable accelerates corrosion and aging, significantly impacting the tensile strength of the boom. This detection device, by compensating for the distorted magnetic field of the metal anchor head and cable inside the protective cover, can accurately detect small amounts of moisture adhering to the steel cable in the anchor head, identifying and detecting corrosion and water seepage inside the boom head in advance. Early identification and prevention of defects such as water seepage and corrosion enable early detection and warning of these problems, reducing safety hazards and improving detection effectiveness.

[0063] In some embodiments, the compensation coil 152 is a ring coil group or a saddle-shaped coil group. The ring coil group is only used for magnetic field compensation in the radial direction of the ring component 11, while the saddle-shaped coil group can further compensate the magnetic field in the radial and axial directions of the ring component 11 to improve the magnetic field compensation effect.

[0064] In some embodiments, to improve accuracy and data reliability during the testing process, multi-point retesting can be employed. The anchor head protective cover 2 is tested in its upper, middle, and lower regions along its longitudinal direction to identify water accumulation at different locations inside the cover. Multiple tests are performed on the same location during the testing process, and the average value is recorded and stored to avoid randomness in the test data.

[0065] Furthermore, after the inspection of a single anchor head casing is completed, the inspection device 1 can upload the inspection data to the PC system for subsequent monitoring and analysis. By comparing and analyzing the data differences of the boom protector 2 at different locations, abnormal locations can be accurately located, and early identification of localized corrosion can be achieved.

[0066] The technical solution described in the embodiment of the present invention for the water accumulation detection device at the suspender head of a tied arch bridge can achieve at least the following beneficial effects: (1) The detection device is equipped with a nuclear magnetic signal transmission module and a nuclear magnetic signal receiving module. It uses nuclear magnetic resonance (NMR) technology to achieve non-destructive testing of water accumulation inside the anchor head protective cover without damaging the original structure of the anchor head protective cover. It can avoid secondary damage to the suspender structure during the testing process, greatly reduce the manpower, financial resources and time costs of testing, and help improve the efficiency of bridge maintenance, so as to facilitate a comprehensive inspection of tied arch bridges on a regular basis.

[0067] (2) The detection device is also equipped with an adjusting arm assembly, which can fit the ring assembly onto the anchor head protective cover under the bridge deck. The staff does not need to go down to the bottom of the bridge during the detection. The detection work can be carried out on the bridge deck, which helps to simplify the detection steps and improve the safety and convenience of the detection work.

[0068] (3) The ring assembly is equipped with a centering adjustment component to improve the concentricity and stability of the ring assembly and the anchor head protective cover during the detection process, which is conducive to improving the detection accuracy and reducing errors.

[0069] (4) The detection device is also equipped with a magnetic field compensation module, which is used to actively compensate for the distortion effect of the metal structure in the test area on the NMR signal, which can improve the detection accuracy and anti-interference ability; it can also realize the detection of the inside of metal protective covers such as stainless steel, which is conducive to expanding the application scenarios.

[0070] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments of the invention herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of the invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave.

[0071] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0072] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for detecting water accumulation at the suspender head of a tied-arch bridge, characterized in that, The detection device (1) includes: An annular component (11) is coaxially fitted onto the outside of the anchor head protective cover (2) of the boom, so that the central area of ​​the annular component (11) corresponds to the location of the water accumulation area inside the anchor head protective cover (2). The main structure (12) includes a nuclear magnetic signal transmitting module (121), a nuclear magnetic signal receiving module (122), a power supply module (123), and a data processing module (124). The nuclear magnetic resonance (NMR) signal transmitting module (121) includes a radio frequency (RF) coil (121-1) and an NMR signal transmitter (121-2). The power supply module (123) is circuitically connected to the NMR signal transmitter (121-2) so that the NMR signal transmitter (121-2) can output RF excitation pulses at the Ramohr frequency. The RF coil (121-1) is coaxially disposed inside the annular assembly (11), and the NMR signal transmitter (121-2) is circuitally connected to the RF coil (121-1) so that in the transmitting state, the NMR signal transmitting module (121) can transmit RF excitation pulses to the water accumulation test area through the RF coil (121-1). The nuclear magnetic resonance signal receiving module (122) includes an induction coil (122-1) and a nuclear magnetic resonance signal acquisition device (122-2); the induction coil (122-1) is coaxially disposed inside the ring assembly (11), and the induction coil (122-1) is circuitally connected to the nuclear magnetic resonance signal acquisition device (122-2) for receiving nuclear magnetic resonance echo signals generated by proton relaxation inside the region to be measured; The nuclear magnetic resonance signal acquisition device (122-2) is connected to the data processing module (124) in a circuit. The data processing module (124) is used to obtain NMR data based on the nuclear magnetic resonance echo signal and to identify the water accumulation status in the area to be tested based on the NMR data.

2. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 1, characterized in that, The radio frequency coil (121-1) and the induction coil (122-1) are configured as a wound coil group, and the nuclear magnetic resonance signal transmitter (121-2) and the nuclear magnetic resonance signal collector (122-2) are connected to the coil group circuit through a selection control circuit; The selection control circuit is configured such that, in the transmission state, the nuclear magnetic resonance signal collector (122-2) is disconnected from the coil group circuit, and the nuclear magnetic resonance signal transmitter (121-2) is connected to the coil group circuit; in the reception state, the nuclear magnetic resonance signal transmitter (121-2) is disconnected from the coil group circuit, and the nuclear magnetic resonance signal collector (122-2) is connected to the coil group circuit.

3. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 1, characterized in that, The radio frequency coil (121-1) and the induction coil (122-1) are configured as two winding coil groups, and the radio frequency coil (121-1) and the induction coil (122-1) are arranged coaxially. In the radial direction of the annular assembly (11), the radio frequency coil (121-1) and the induction coil (122-1) are nested inside and outside, with the radio frequency coil (121-1) located outside the induction coil (122-1).

4. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 1, characterized in that, The detection device (1) also includes an adjusting arm assembly (13), which is C-shaped in whole or in part; The main structure (12) is located on the upper bridge surface of the tie-arch bridge. One end of the adjusting arm assembly (13) is connected to the main structure (12), and the other end is connected to the ring assembly (11). The main structure (12) and the ring assembly (11) are located on the same side of the adjusting arm assembly (13). The middle part of the adjusting arm assembly (13) has a clearance space formed by the bending part of the C-shaped structure, which is used to avoid the outer edge structure of the bridge deck in the width direction of the tie-arch bridge, so that the ring assembly (11) can move from the upper bridge deck position to the position below the bridge deck corresponding to the area to be tested through the adjusting arm assembly (13) in the detection state.

5. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 4, characterized in that, The adjusting arm assembly (13) is provided with a vision module (14), including a camera (141) and a display screen (142). The camera (141) is located at one end of the adjusting arm assembly (13) that connects to the annular assembly (11); the display screen (142) is located on the main structure (12) and is used to display the spatial relative position of the annular assembly (11) and the anchor head protective cover (2).

6. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 4, characterized in that, The adjusting arm assembly (13) includes: a first lateral adjusting mechanism (131), a vertical adjusting mechanism (132), a second lateral adjusting mechanism (133), and a rotation adjusting mechanism (134). One end of the first lateral adjustment mechanism (131) is fixedly connected to the main structure (12), and the other end is connected to the upper end of the vertical adjustment mechanism (132); One end of the second lateral adjustment mechanism (133) is connected to the ring assembly (11), and the other end is connected to the lower end of the vertical adjustment mechanism (132); At least one end of the vertical adjustment mechanism (132) is provided with the rotation adjustment mechanism (134) so ​​as to be rotatably connected to the first horizontal adjustment mechanism (131) and / or the second horizontal adjustment mechanism (133).

7. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 4, characterized in that, The adjusting arm assembly (13) adopts a telescopic sleeve structure or a multi-joint swing arm structure.

8. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 2, characterized in that, The ring assembly (11) includes a centering adjustment mechanism (111); The centering adjustment mechanism (111) includes at least three sets of push-pull wheel assemblies; the push-pull wheel assemblies are evenly arranged in the circumferential direction of the annular assembly (11); A single push-pull wheel assembly includes a push-pull wheel (111-1), a spring (111-2), and a mounting base (111-3). The vertical adjustment mechanism (111-3) is fixedly mounted on the annular assembly (11). The push-pull wheel (111-1) is connected to the mounting base (111-3) through the spring (111-2). The push-pull wheel (111-1) is used to contact and abut against the outer wall of the anchor head protective cover (2).

9. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 1, characterized in that, The detection device (1) further includes a magnetic field compensation module (15), which is equipped with a magnetic sensor (151) and a compensation coil (152). The magnetic sensor (151) is disposed inside the annular assembly (11) and is used to detect the magnetic field distortion signal generated by the anchor head protective cover (2) or the metal anchor head in the area to be tested. The compensation coil (152) is coaxially arranged inside the annular assembly (11), and the compensation coil (152) is located around the radio frequency coil (121-1) and the induction coil (122-1); the magnetic sensor (151) and the compensation coil (152) are both circuit-connected to the data processing module (124), and the data processing module (124) is used to apply a reverse compensation magnetic field to the area to be measured through the compensation coil (152) according to the magnetic field distortion signal, so as to cancel the metal interference.

10. The device for detecting water accumulation at the suspender head of a tied-arch bridge according to claim 1, characterized in that, The compensation coil (152) adopts a ring coil group or a saddle-shaped coil group.

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