A sensor and monitoring system for monitoring tangential relative deformation at a structural interface

Abstract

The application discloses a kind of sensor and monitoring system for structural interface tangential relative deformation monitoring, belong to structural displacement monitoring technical field.Sensor includes sealed shell, LVDT coil assembly, LVDT core, displacement transmission rod, wing plate A, wing plate B, transverse rack push rod A, transverse rack push rod B, transverse push rod spring A, transverse push rod spring B, transmission gear set, LVDT core transmission rod, guide ring A, guide ring B and guide ring spring group.Wing plate A and wing plate B are vertically fixed in space on displacement transmission rod, are respectively driven transmission gear set rotation by transverse rack push rod, and then drive LVDT core transmission rod to drive LVDT core axial sliding in LVDT coil assembly, realize interface tangential displacement to LVDT measurable axial displacement conversion.The application realizes the high accuracy, long-term stable monitoring of interface tangential deformation.

Description

Technical Field

[0001] This invention belongs to the field of structural displacement monitoring technology, specifically relating to a sensor and monitoring system for monitoring the tangential relative deformation of structural interfaces. Background Technology

[0002] With the continuous development of transportation infrastructure in my country, projects such as cross-sea channels, river-crossing tunnels, urban rail transit, and large-scale underground complexes are increasing. In these projects, the structure is often composed of several segments connected by joints, or a combination of structures made of different materials. Joints and the interfaces between different structural materials are the weakest points in the entire structural system, exhibiting the most complex mechanical behavior and being most prone to failure. Taking an immersed tunnel as an example, the tunnel is constructed by joining several precast concrete sections underwater. The joints not only bear enormous water and soil pressures but are also subjected to the long-term effects of uneven foundation settlement, temperature stress, and tidal cyclic loads. Tangential slippage at the joints is one of the main causes of shear failure of the GINA waterstop and joint leakage. Similarly, in shield tunnels, tangential slippage at the circumferential and longitudinal joints of the tunnel segments directly affects the overall stability and waterproofing performance of the lining ring. In addition, uneven deformation and tangential relative displacement due to stiffness differences and unbalanced loads are common between bridge supports and beams, at structural connections in bridge-tunnel transition sections, between the main body of underground stations and entrance / exit passages, and between high embankment roadbeds and structures.

[0003] In existing technologies, common displacement monitoring methods include rod-type resistance displacement gauges, vibrating wire displacement gauges, fiber optic grating displacement gauges, capacitive / eddy current displacement sensors, and linear variable differential transformer (LVDT) displacement sensors. Among these, LVDTs utilize the principle of primary coil excitation and secondary coil differential output to measure the axial linear displacement of the iron core. They possess outstanding advantages such as extremely high measurement accuracy (resolution up to sub-micrometer level), good linearity (0.1%~0.5% FS), large output signal, frictionless measurement, and long service life. However, the inherent limitation of LVDTs is that they can only measure the linear displacement of the iron core along the coil axis and cannot directly measure the tangential displacement perpendicular to the axial direction. If the LVDT is installed at an angle, its measurement value is the coupling result of the tangential and normal components, and cannot reflect the tangential displacement of the interface independently. Other types of displacement sensors also generally suffer from problems such as limited measurement direction, difficulty in balancing accuracy and range, and insufficient environmental adaptability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a sensor and monitoring system for monitoring the tangential relative deformation of structural interfaces. This system can fully utilize the high precision advantages of LVDT and cleverly convert the tangential displacement of the interface into the axial displacement of the LVDT core.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a sensor for monitoring tangential relative deformation of a structural interface, comprising:

[0007] A sealed housing for fixing and installing on a structure on the first side of the interface;

[0008] An LVDT coil assembly is fixedly disposed inside the sealed housing, and the axial direction of the LVDT coil assembly is consistent with the length direction of the sealed housing;

[0009] The LVDT core is slidably disposed inside the LVDT coil assembly along the length of the sealed housing;

[0010] A displacement transmission rod extends through the sealing housing along its length. The first end of the displacement transmission rod extends out of the sealing housing and is used to connect and fix it to a structure on the second side of the interface. The second end of the displacement transmission rod is located inside the sealing housing.

[0011] Wing A and wing B are both fixedly installed on the portion of the displacement transmission rod located inside the sealed housing, and the surface of wing A and the surface of wing B are perpendicular to each other in space;

[0012] Transverse rack push rod A and transverse rack push rod B are slidably disposed inside the sealing housing in a direction perpendicular to the axial direction of the displacement transmission rod. The first end of the transverse rack push rod A abuts against the plate surface of the wing plate A, and the first end of the transverse rack push rod B abuts against the plate surface of the wing plate B. At least a portion of the rod segment of each transverse rack push rod is provided with tooth grooves.

[0013] Lateral push rod spring A and lateral push rod spring B are respectively sleeved on lateral rack push rod A and lateral rack push rod B. One end of each lateral push rod spring abuts against the corresponding lateral rack push rod, and the other end abuts against the inner wall of the sealing housing, for providing elastic thrust toward the wing plate A and wing plate B to the corresponding lateral rack push rod respectively.

[0014] A transmission gear set is rotatably disposed inside the sealed housing. The transmission gear set includes a gear A and a gear B that are coaxially fixed and have the same angular displacement. The gear A meshes with the tooth groove of one of the transverse rack push rod A and the transverse rack push rod B, and the gear B meshes with the tooth groove of the other of the transverse rack push rod A and the transverse rack push rod B.

[0015] The LVDT core drive rod has a first end fixedly connected to the LVDT core, and a second end provided with a toothed groove that meshes with gear A or gear B. The LVDT core drive rod drives the LVDT core to slide axially within the LVDT coil assembly under the drive of the transmission gear set.

[0016] Guide ring A and guide ring B are respectively fixedly disposed at both ends of the displacement transmission rod located inside the sealing housing. A gap is left between the outer periphery of each guide ring and the inner wall of the sealing housing to constrain the radial position of the displacement transmission rod relative to the sealing housing.

[0017] And a guide ring spring assembly, which respectively connects each guide ring to the inner wall of the sealing housing, for holding the displacement transmission rod at the axial position of the sealing housing.

[0018] Both wing plate A and wing plate B are welded and fixed to the displacement transmission rod;

[0019] The non-groove ends of both the transverse rack push rod A and the transverse rack push rod B are set as arc surfaces, forming line contact or point contact with the plate surface of the wing plate A and the plate surface of the wing plate B, respectively.

[0020] One end of the transverse push rod spring A abuts against the shoulder of the transverse rack push rod A, and the other end abuts against the inner wall of the sealing housing; one end of the transverse push rod spring B abuts against the shoulder of the transverse rack push rod B, and the other end abuts against the inner wall of the sealing housing.

[0021] Each guide ring has multiple pull rings symmetrically arranged around its periphery. The guide ring spring assembly includes springs in the same number as the pull rings. One end of each spring is connected to the corresponding pull ring, and the other end is connected to the inner wall of the sealing housing. The elastic forces of each spring on the same guide ring are balanced with each other so that the displacement transmission rod is kept at the axial position of the sealing housing.

[0022] The sealing housing includes a main cavity and an end cap. An O-ring and a metal gasket are provided between the main cavity and the end cap to form a double sealing structure.

[0023] The sealed housing is filled with insulating and thermally conductive silicone oil, and a flexible pressure balancing membrane is provided on the inner side of the end cap of the sealed housing. The flexible pressure balancing membrane isolates the insulating and thermally conductive silicone oil from the water outside the sealed housing, and is used to balance the pressure inside and outside the sealed housing.

[0024] Gear A has a pitch circle radius of R and a number of teeth of N, and gear B has a pitch circle radius of r and a number of teeth of M. Gear A and gear B are coaxially fixed and satisfy the following conditions:

[0025] The linear displacement ΔL1 of the transverse rack pusher A and the component ΔX1 of the tangential relative displacement ΔX of the interface in the first direction satisfy the following relationship: ;

[0026] The linear displacement ΔL2 of the transverse rack pusher B and the component ΔX2 of the interface tangential relative displacement ΔX in the second direction satisfy the following relationship: ;

[0027] Wherein, the first direction and the second direction are perpendicular to each other, and satisfy:

[0028] .

[0029] In a second aspect, the present invention provides a monitoring system for monitoring the tangential relative deformation of a structural interface, comprising at least one of the aforementioned sensors;

[0030] The signal conditioning module is integrated inside the sealed housing and electrically connected to the LVDT coil assembly. The signal conditioning module includes a sinusoidal excitation source, a phase-sensitive rectifier, a low-pass filter, and a voltage / current conversion circuit. The sinusoidal excitation source is used to provide an excitation signal to the LVDT coil assembly. The phase-sensitive rectifier, the low-pass filter, and the voltage / current conversion circuit are used to demodulate, filter, and amplify the differential signal output by the LVDT coil assembly to output a standardized electrical signal.

[0031] The data acquisition terminal is communicatively connected to the signal conditioning module and is used to receive and record the standardized electrical signal.

[0032] It also includes a data processing and analysis module, used to calculate the tangential relative displacement based on the standardized electrical signal interface, and to store, display, and perform early warning analysis of the monitoring data.

[0033] The signal conditioning module also includes a temperature compensation circuit, which has a built-in thermistor located near the LVDT coil assembly to compensate for measurement drift caused by temperature changes in the LVDT coil assembly.

[0034] The standardized electrical signal output by the signal conditioning module is a 4-20mA current signal or an RS-485 digital signal.

[0035] The data acquisition terminal includes a multi-channel high-precision acquisition module with a sampling rate of no less than 200Hz per channel and an analog-to-digital conversion resolution of no less than 16 bits. The data acquisition terminal is also equipped with a local storage module and a wireless communication module, supporting three working modes: timed acquisition, triggered acquisition, and real-time continuous acquisition.

[0036] The data processing and analysis module, according to The tangential relative displacement of the interface is calculated, where ΔL1 and ΔL2 are the linear displacements of the transverse rack push rod A and the transverse rack push rod B, respectively. The linear displacements are obtained by conversion based on the transmission ratio of the transmission gear set and the axial displacement of the LVDT core.

[0037] The data processing and analysis module has a built-in temperature drift compensation algorithm and a gear tooth backlash error compensation algorithm to correct errors in the measurement results; the data processing and analysis module also has a multi-level threshold alarm function to issue different levels of early warning signals in real time based on the relative tangential displacement of the interface.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] This invention decomposes the interfacial tangential displacement into two mutually perpendicular components using wing plates A and B. Then, a transverse rack and pinion pusher and a transmission gear set convert the linear motion into rotational motion, which in turn drives the LVDT core transmission rod to slide the LVDT core axially. This achieves the technical effect of converting the interfacial tangential displacement into a measurable axial displacement by the LVDT. The sensor fully utilizes the sub-micron resolution measurement advantage of the LVDT. Laboratory calibration tests show that the system's measurement accuracy can reach ±0.02mm. By rationally designing the gear transmission ratio, the sensor's range and resolution can be flexibly adjusted without replacing the LVDT body. The LVDT operates on a non-contact measurement principle, and the gear transmission uses rolling bearings and wear-resistant materials, ensuring good long-term stability. The sealed housing withstands pressure ≥2MPa and has an IP68 protection rating, making it suitable for deep-water, high-pressure environments. The LVDT core has a small mass, and the mechanical conversion mechanism has a small moment of inertia, resulting in a frequency response of over 100Hz, making it suitable for real-time deformation monitoring under dynamic loads. The signal conditioning module directly outputs a 4~20mA standard signal or an RS-485 digital signal, compatible with mainstream data acquisition systems. This invention successfully solves the technical problem that traditional LVDT cannot directly measure tangential displacement, and provides a complete technical solution for the safety monitoring of the structural interface of large infrastructure. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments are briefly introduced below.

[0041] Figure 1 This is a schematic cross-sectional view of the overall structure of the sensor of the present invention;

[0042] Figure 2 for Figure 1 Schematic diagram of section AA;

[0043] Figure 3 for Figure 1 Schematic diagram of the BB section;

[0044] Figure 4 for Figure 1 Schematic diagram of the CC section;

[0045] Figure 5 for Figure 1 Schematic diagram of the DD section;

[0046] Figure 6 This is a partially enlarged schematic diagram of the gear transmission conversion mechanism in this invention;

[0047] Figure 7 This is a schematic diagram showing the installation and layout of the sensor of the present invention at the joint of the immersed tunnel section;

[0048] Figure 8 This is a schematic diagram of the sensor of the present invention installed at the structural interface;

[0049] Figure 9 This is a block diagram of the LVDT signal conditioning and data acquisition system in this invention.

[0050] The meanings of the markings in the attached diagram are as follows:

[0051] 1. Sealed housing; 2. LVDT coil assembly; 3. LVDT core; 4. Displacement transmission rod; 5. Wing plate A; 6. Wing plate B; 7. Lateral rack push rod A; 8. Lateral rack push rod B; 9. Lateral push rod spring A; 10. Lateral push rod spring B; 11. Transmission gear set; 11a. Gear A; 11b. Gear B; 12. LVDT core transmission rod; 13. Guide ring A; 14. Guide ring B; 15. Guide ring spring set; 16. Pull ring; 17. Flexible pressure balancing diaphragm; 18. Signal cable; 19. Fixed ear plate; 20. Pipe section A; 21. Pipe section B; 22. GINA waterstop; 23. Thermistor. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the specific embodiments of this invention will be described in detail below with reference to the accompanying drawings. The following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this invention. Those skilled in the art can make various modifications or equivalent substitutions to the embodiments without departing from the concept of this invention, but all such modifications or substitutions should fall within the protection scope of this invention.

[0053] Example 1: Monitoring of Tangential Displacement at the Joint of Submarine Immersed Tunnel Segments

[0054] This embodiment uses a subsea immersed tunnel spanning a deep-water channel as an example. The tunnel is approximately 40m deep with a maximum water pressure of about 0.5MPa. It is constructed from 22 precast concrete pipe sections joined together via underwater flexible joints. A standard pipe section is 180m long, 40m wide, and 11m high. The joints are equipped with GINA and OMEGA waterstops. The GINA waterstop is a hollow section made of natural rubber. Watertight sealing is achieved through compression deformation under the final hydraulic pressure of the pipe section during the joint connection. The tangential misalignment of the joint directly affects the safety of the waterstop system.

[0055] The sensor structure used in this embodiment is as follows: Figures 1 to 6 As shown, the sealing housing 1 of the sensor is a flat rectangular or cylindrical shape, integrally machined from 316L stainless steel, with a wall thickness of 4mm. The sealing housing 1 is mounted on the structure on the first side of the interface via a fixing lug 19. Inside, along the length direction, there are a guide ring A 13, a wing plate A 5, a transmission gear set 11, a wing plate B 6, and a guide ring B 14 arranged sequentially.

[0056] The displacement transmission rod 4 extends through the entire interior of the sealing housing 1 along its length. Its left end extends out of the sealing housing 1 and is used to connect and fix it to the structure on the second side of the interface, while its right end is located inside the sealing housing 1. Guide rings A 13 and B 14 are respectively fixedly installed at the left and right ends of the displacement transmission rod 4 inside the sealing housing 1. Multiple pull rings 16 are symmetrically arranged around the periphery of guide rings A 13 and B 14. Guide ring spring groups 15 connect each pull ring 16 to the inner wall of the sealing housing 1. The elastic forces of each spring are balanced, keeping the displacement transmission rod 4 at the axial position of the sealing housing 1, while also constraining the radial position of the displacement transmission rod 4 relative to the sealing housing 1.

[0057] Both wing plates A5 and B6 are welded and fixed to the portion of the displacement transmission rod 4 located inside the sealing housing 1. Wing plate A5 is a horizontally extending plate with its surface in a horizontal plane; wing plate B6 is a vertically extending plate with its surface in a vertical plane. Wing plates A5 and B6 are spatially perpendicular to each other and are spaced apart along the axial direction of the displacement transmission rod 4, corresponding to two different axial positions within the sealing housing 1.

[0058] A transverse rack push rod A7 is slidably disposed inside the sealing housing 1 in a direction perpendicular to the axial direction of the displacement transmission rod 4. Its left end (non-grooved end) abuts against the surface of the wing plate A5, and its right end is provided with a groove. A transverse push rod spring A9 is sleeved on the transverse rack push rod A7, with one end abutting against the shoulder of the transverse rack push rod A7 and the other end abutting against the inner wall of the sealing housing 1. It is used to provide an elastic thrust to the transverse rack push rod A7 toward the wing plate A5, ensuring that the non-grooved end of the transverse rack push rod A7 always maintains close contact with the surface of the wing plate A5.

[0059] The transverse rack push rod B8 is slidably disposed inside the sealing housing 1 in a direction perpendicular to the axial direction of the displacement transmission rod 4, and its direction of movement is perpendicular to the direction of movement of the transverse rack push rod A7. The lower end (non-grooved end) of the transverse rack push rod B8 abuts against the surface of the wing plate B6, and its upper end is provided with a groove. The transverse push rod spring B10 is sleeved on the transverse rack push rod B8, with one end abutting against the shoulder of the transverse rack push rod B8 and the other end abutting against the inner wall of the sealing housing 1, and is used to provide elastic thrust to the transverse rack push rod B8 toward the wing plate B6 to ensure that the non-grooved end of the transverse rack push rod B8 always maintains close contact with the surface of the wing plate B6.

[0060] The transmission gear set 11 is disposed inside the sealed housing 1, located axially between wing plate A 5 and wing plate B 6. The transmission gear set 11 includes gear A 11a and gear B 11b, which are coaxially fixed and have the same angular displacement. Gear B 11b meshes with the tooth grooves of both transverse rack push rod A 7 and transverse rack push rod B 8; gear A 11a meshes with the tooth groove of LVDT iron core transmission rod 12.

[0061] The LVDT coil assembly 2 is fixedly disposed inside the sealed housing 1, located on the right side of the transmission gear set 11, with its axial direction aligned with the length direction of the sealed housing 1. The LVDT core 3 is slidably disposed inside the LVDT coil assembly 2 along the length direction of the sealed housing 1, with its left end fixedly connected to the right end of the LVDT core transmission rod 12. The LVDT core transmission rod 12 extends along the length direction of the sealed housing 1, with a toothed groove at its left end that meshes with gear A 11a. When the transverse rack push rod A 7 or the transverse rack push rod B 8 undergoes linear displacement, the drive gear B 11b rotates, and the coaxial gear A 11a rotates synchronously, thereby driving the LVDT core transmission rod 12 to slide axially, causing the LVDT core 3 to move linearly axially within the LVDT coil assembly 2.

[0062] A flexible pressure balancing diaphragm 17 is provided on the inner side of the right end cap of the sealed housing 1, and the interior of the housing is filled with insulating and thermally conductive silicone oil. The flexible pressure balancing diaphragm 17 is a flexible diaphragm made of fluororubber or silicone rubber, which isolates the internal silicone oil from the external water, making the internal and external pressure difference close to zero, thereby reducing the pressure load on the sealing structure. A thermistor 23 is provided near the LVDT coil assembly 2 for real-time temperature monitoring and temperature drift compensation of the output signal of the LVDT coil assembly 2. The signal conditioning module is integrated on the circuit board inside the sealed housing 1 and is electrically connected to the LVDT coil assembly 2. The signal cable 18 extends from the right end of the sealed housing 1 and exits with an IP68 watertight connector.

[0063] The monitoring system in this embodiment is as follows: Figure 9 As shown, the system includes a sensor body, a signal conditioning module integrated within a sealed housing 1, a data acquisition terminal, and a data processing and analysis module. The signal conditioning module includes a sinusoidal excitation source, a phase-sensitive rectifier, a low-pass filter, and a voltage-to-current conversion circuit. It provides an excitation signal to the LVDT coil assembly 2 and demodulates, amplifies, and filters the differential signal output from the LVDT coil assembly 2, outputting a standardized 4-20mA current signal. The data acquisition terminal communicates with the signal conditioning module to receive and record this current signal. The data processing and analysis module calculates the tangential relative displacement of the interface based on the acquired data and performs data storage, display, and early warning analysis.

[0064] Based on the geological survey report and finite element calculations, the maximum tangential misalignment of this joint within its design service life is ±35mm. The gear transmission ratio is selected accordingly. The pitch circle radius of gear B 11b is r = 4mm, and the pitch circle radius of gear A 11a is R = 20mm. When the tangential displacement of the interface is ±35mm, the actual stroke of the LVDT core 3 is ±7mm, and the range of the selected LVDT coil assembly 2 is ±10mm, which meets the usage requirements and provides a safety margin. Finite element simulation analysis verifies that the 4mm thick 316L stainless steel sealing shell 1 can safely withstand a hydrostatic pressure of 3MPa.

[0065] On-site installation, such as Figure 7As shown, the following steps are performed: (1) Base surface treatment and positioning: The installation area is marked at the end of the joint of pipe section A 20 (interface A side), the loose layer on the surface is removed, and the sensor sealing housing 1 is fixed to the pre-embedded steel plate of the side wall of pipe section A 20 by means of the fixing ear plate 19 using chemical anchors. The axial direction of the sealing housing 1 is calibrated by a high-precision laser level to ensure that it is consistent with the design normal direction of the pipe section joint; (2) Connecting the movable end: The outer end of the displacement transmission rod 4 is fixedly connected to the pre-embedded part of pipe section B 21 (interface B side); (3) Cable and watertight treatment: The signal cable 18 is laid along the pre-embedded cable trough of the tunnel side wall to the nearby data acquisition station. The cable joint adopts the IP68 watertight joint. The joint is potted with epoxy resin and wrapped with waterproof tape to strengthen the protection; (4) System commissioning: The displacement transmission rod 4 is pushed by a high-precision micrometer to apply a known standard displacement, the output coefficient of each sensor is calibrated and recorded, and the initial value is archived.

[0066] The working process is as follows: When pipe section B 21 experiences tangential displacement relative to pipe section A 20 due to temperature changes or uneven foundation settlement, displacement transmission rod 4 drives wing plate A 5 and wing plate B 6 to undergo tangential linear motion. Wing plate A 5 pushes transverse rack push rod A 7 (ensuring tight contact via transverse push rod spring A 9), and the linear displacement of transverse rack push rod A 7 drives gear B 11b to rotate. Coaxial gear A 11a rotates synchronously, thereby driving LVDT core transmission rod 12 to drive LVDT core 3 to move linearly along the axial direction within LVDT coil assembly 2. The differential voltage output from LVDT coil assembly 2 is demodulated and amplified by the signal conditioning module inside the sealed housing 1, and converted into a 4~20mA current signal after temperature compensation by the thermistor 23. This signal is then transmitted in real time to the data acquisition terminal in the tunnel monitoring room via a shielded cable. The acquisition terminal continuously records data at a sampling rate of 200Hz and uploads it to the central server via a fiber optic ring network. The data processing and analysis module then... The tangential relative displacement of the calculation interface is calculated, where ΔL1 and ΔL2 are the linear displacements of the transverse rack push rod A7 and the transverse rack push rod B8, respectively. These linear displacements are obtained by conversion based on the transmission ratio of the transmission gear set 11 and the axial displacement of the LVDT core 3.

[0067] During the first 24 months of operation of the tunnel, the system successfully captured two instances of slow tangential deformation of the joint caused by seasonal temperature differences (approximately +1.2 mm and -0.8 mm), and one instance of transient tangential vibration waveform (maximum amplitude ±4.5 mm) caused by seismic activity in a nearby section. Comparison of the monitoring data with the results of concurrent 3D laser scanning verification showed that the deviation between the two was within ±0.03 mm.

[0068] Example 2: Monitoring of Tangential Slippage at the Circumferential Joint of Shield Tunnel Lining

[0069] This embodiment uses a shield tunnel section in an urban subway as the application object. This section traverses a water-rich sandy and gravelly stratum, and the tunnel segment lining uses a universal wedge-shaped ring. During the excavation of curved sections, the inter-ring shear slippage is prone to occur at the segment ring joints due to uneven lateral pressure from the stratum, which can lead to segment cracking and joint leakage in severe cases. In this embodiment, one set of sensors of this invention is deployed on each of the up and down lines of the three continuous shield tunnel ring joints to monitor the tangential slippage of the ring joints. The sensor structure and monitoring system in this embodiment are consistent with those in Embodiment 1.

[0070] Considering the confined space and misalignment of the tunnel segments, the sensor sealing housing 1 in this embodiment adopts a miniaturized design, reducing its dimensions to two-thirds of the conventional size (length ≤ 180mm, diameter ≤ 50mm), with a measuring range of ±10mm (transmission ratio i = 0.5). The sealing housing 1 is fixed to a pre-embedded groove in one ring segment (interface A side) using expansion bolts, and the displacement transmission rod 4 is fixed to the bolt holes of the adjacent ring segment (interface B side) using an L-shaped adapter bracket. Installation is carried out after the tunnel is completed and before track laying, ensuring that the axis of the displacement transmission rod 4 is aligned with the tangential direction of the segment's circumferential joint. The RS-485 digital signal output by the sensor is connected to the existing automated monitoring system of the tunnel via a bus.

[0071] During six consecutive months of monitoring, the system clearly recorded the periodic tangential micro-movements (amplitude approximately ±0.05 mm) of the circumferential joint caused by train loads during the morning and evening rush hours, as well as a sudden tangential slippage (approximately +2.3 mm) caused by uneven grouting pressure from the tunnel boring machine. The monitoring results indicate that the circumferential joint is in a stable state, providing data support for subsequent grouting reinforcement.

[0072] Example 3: Monitoring of relative deformation at the structural connection of bridge-tunnel transition section

[0073] This embodiment uses a bridge-tunnel transition section of a mountainous expressway as its application example. The tunnel entrance lining is connected to the superstructure of the bridge via a cast-in-place slab. Due to the significant difference in stiffness between the bridge abutment foundation and the tunnel foundation, a noticeable tangential misalignment occurs between the slab and the tunnel entrance under vehicle loads and temperature effects. In this embodiment, two sets of sensors of this invention are deployed on each side of the transition section to achieve redundant monitoring. The sensor and monitoring system structure in this embodiment is consistent with that in Embodiment 1. The on-site installation method is as follows: Figure 8 As shown.

[0074] During installation, the sensor sealing housing 1 is fixed to the pre-embedded steel plate on the tunnel entrance end wall (interface A side) via a welding base, and the fixed end of the displacement transmission rod 4 is installed on the concrete block at the bridge end (interface B side). Since this area is located in an open environment and is subject to rain erosion, a polyurea elastomer anti-corrosion coating is applied to the outside of the sealing housing 1, and the signal cable 18 is protected by a galvanized steel pipe.

[0075] After a summer of high temperatures, sensors detected that the transition section had accumulated a tangential displacement of +6.7mm (the approach slab was pushed towards the bridge span) under extreme high temperatures, exceeding the preset yellow warning threshold of +5mm. The system promptly triggered an alert, and the maintenance unit accordingly reinforced the end of the approach slab to limit its movement, effectively preventing pavement cracking caused by excessive displacement.

[0076] Example 4: Laboratory Accuracy Calibration and Dynamic Testing

[0077] In this embodiment, the tangential relative motion of the interface is simulated in a laboratory environment to systematically calibrate and verify the measurement accuracy, dynamic response characteristics, and repeatability of the sensor of the present invention. The structure of the sensor under test is consistent with that in embodiments 1 to 3.

[0078] Experimental setup: A high-precision electro-hydraulic servo loading system (MTS 793) was used as the interface tangential displacement drive source, with a built-in LVDT (accuracy 0.5μm) as the standard reference. The sensor under test was configured according to the parameters in Example 1. The sensor under test was placed in a pressure tank, and a water pressure of 2MPa was applied and maintained for 48 hours.

[0079] Static accuracy test: Forward and reverse stroke loading were performed in steps of 0.5 mm within the range of 0~30 mm. The results show that the maximum linearity error of the sensor of this invention is 0.22% FS, the repeatability error is less than 0.01 mm, and the maximum deviation from the standard LVDT reference value is +0.018 mm.

[0080] Dynamic response test: A sinusoidal tangential displacement with a frequency of 20Hz and an amplitude of ±1mm was applied. The sensor output signal waveform closely matched the MTS system command waveform, with a phase lag of less than 3°, confirming that it meets the requirements for dynamic deformation monitoring.

[0081] Anti-interference test: The sensor output zero drift was less than 0.005 mm after being pressurized and depressurized in the water pressure tank from 0 to 2.5 MPa, proving the effectiveness of the flexible pressure balance diaphragm 17 and the sealing design.

[0082] In summary, the sensor and monitoring system proposed in this invention for monitoring the tangential relative deformation of structural interfaces, through gear transmission conversion mechanism and sealing design, can be widely applied to various engineering environments from deep-sea submarine tunnels and urban subways to bridge transition sections. It has the advantages of high accuracy, good long-term stability, adjustable range and fast dynamic response, and provides a complete technical solution for the safety monitoring of structural interfaces of large infrastructure.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A sensor for monitoring tangential relative deformation of structural interfaces, characterized in that, include: A sealed housing (1) is used to be fixedly installed on a structure on the first side of the interface; The LVDT coil assembly (2) is fixedly disposed inside the sealed housing (1), and the axial direction of the LVDT coil assembly (2) is consistent with the length direction of the sealed housing (1); The LVDT core (3) is slidably disposed inside the LVDT coil assembly (2) along the length direction of the sealed housing (1); The displacement transmission rod (4) extends through the sealing housing (1) along its length direction. The first end of the displacement transmission rod (4) extends out of the sealing housing (1) and is used to connect and fix it to the structure on the second side of the interface. The second end of the displacement transmission rod (4) is located inside the sealing housing (1). Wing plate A (5) and wing plate B (6) are both fixedly installed on the part of the displacement transmission rod (4) located inside the sealed housing (1). The plate surface of wing plate A (5) and the plate surface of wing plate B (6) are perpendicular to each other in space. Transverse rack push rod A (7) and transverse rack push rod B (8) are slidably disposed inside the sealing housing (1) in a direction perpendicular to the axial direction of the displacement transmission rod (4). The first end of the transverse rack push rod A (7) abuts against the plate surface of the wing plate A (5), and the first end of the transverse rack push rod B (8) abuts against the plate surface of the wing plate B (6). At least a portion of the rod segment of each transverse rack push rod is provided with tooth grooves. Lateral push rod spring A (9) and lateral push rod spring B (10) are respectively sleeved on the lateral rack push rod A (7) and the lateral rack push rod B (8). One end of each lateral push rod spring abuts against the corresponding lateral rack push rod, and the other end abuts against the inner wall of the sealing housing (1), for providing elastic thrust toward the wing plate A (5) and the wing plate B (6) to the corresponding lateral rack push rod respectively; A transmission gear set (11) is rotatably disposed inside the sealed housing (1). The transmission gear set (11) includes a gear A (11a) and a gear B (11b) that are coaxially fixed and have the same angular displacement. The gear A (11a) meshes with the tooth groove of one of the transverse rack push rod A (7) and the transverse rack push rod B (8). The gear B (11b) meshes with the tooth groove of the other of the transverse rack push rod A (7) and the transverse rack push rod B (8). The LVDT core drive rod (12) has its first end fixedly connected to the LVDT core (3), and its second end is provided with a tooth groove and meshes with the gear A (11a) or the gear B (11b). Under the drive of the transmission gear set (11), the LVDT core drive rod (12) drives the LVDT core (3) to slide axially in the LVDT coil assembly (2). Guide ring A (13) and guide ring B (14) are respectively fixedly installed at both ends of the displacement transmission rod (4) located inside the sealing housing (1). A gap is left between the outer periphery of each guide ring and the inner wall of the sealing housing (1) to constrain the radial position of the displacement transmission rod (4) relative to the sealing housing (1). And guide ring spring assembly (15), which respectively connects each guide ring to the inner wall of the sealing housing (1) to keep the displacement transmission rod (4) at the axial position of the sealing housing (1).

2. The sensor for monitoring tangential relative deformation of structural interfaces according to claim 1, characterized in that, Both the wing plate A (5) and the wing plate B (6) are welded and fixed to the displacement transmission rod (4); The non-toothed ends of the transverse rack push rod A (7) and the transverse rack push rod B (8) are both set as arc surfaces, forming line contact or point contact with the plate surface of the wing plate A (5) and the plate surface of the wing plate B (6), respectively. One end of the transverse push rod spring A (9) abuts against the shoulder of the transverse rack push rod A (7), and the other end abuts against the inner wall of the sealing housing (1); one end of the transverse push rod spring B (10) abuts against the shoulder of the transverse rack push rod B (8), and the other end abuts against the inner wall of the sealing housing (1).

3. The sensor for monitoring tangential relative deformation of structural interfaces according to claim 1, characterized in that, Each guide ring is symmetrically provided with multiple pull rings (16) around its periphery. The guide ring spring assembly (15) includes the same number of springs as the pull rings (16). One end of each spring is connected to the corresponding pull ring (16), and the other end is connected to the inner wall of the sealing housing (1). The elastic forces of each spring on the same guide ring are balanced with each other so that the displacement transmission rod (4) is kept at the axial position of the sealing housing (1).

4. The sensor for monitoring tangential relative deformation of structural interfaces according to claim 1, characterized in that, The sealing housing (1) includes a main cavity and an end cap. An O-ring and a metal gasket are provided between the main cavity and the end cap to form a double sealing structure. The sealed housing (1) is filled with insulating and thermally conductive silicone oil, and a flexible pressure balancing membrane (17) is provided on the inner side of the end cap of the sealed housing (1). The flexible pressure balancing membrane (17) isolates the insulating and thermally conductive silicone oil from the water outside the sealed housing (1) and is used to balance the pressure inside and outside the sealed housing (1).

5. The sensor for monitoring tangential relative deformation of structural interfaces according to claim 1, characterized in that, The pitch circle radius of gear A (11a) is R and the number of teeth is N. The pitch circle radius of gear B (11b) is r and the number of teeth is M. Gear A (11a) and gear B (11b) are coaxially fixed and satisfy the following conditions: The linear displacement ΔL1 of the transverse rack pusher A (7) and the component ΔX1 of the interface tangential relative displacement ΔX in the first direction satisfy the following relationship: ; The linear displacement ΔL2 of the transverse rack pusher B (8) and the component ΔX2 of the interface tangential relative displacement ΔX in the second direction satisfy the following relationship: ; Wherein, the first direction and the second direction are perpendicular to each other, and satisfy: 。 6. A monitoring system for monitoring tangential relative deformation of structural interfaces, characterized in that, include: At least one sensor as described in any one of claims 1 to 5; The signal conditioning module is integrated inside the sealed housing (1) and electrically connected to the LVDT coil assembly (2). The signal conditioning module includes a sine wave excitation source, a phase-sensitive rectifier, a low-pass filter, and a voltage / current conversion circuit. The sine wave excitation source is used to provide an excitation signal to the LVDT coil assembly (2). The phase-sensitive rectifier, the low-pass filter, and the voltage / current conversion circuit are used to demodulate, filter, and amplify the differential signal output by the LVDT coil assembly (2) to output a standardized electrical signal. The data acquisition terminal is communicatively connected to the signal conditioning module and is used to receive and record the standardized electrical signal. It also includes a data processing and analysis module, used to calculate the tangential relative displacement based on the standardized electrical signal interface, and to store, display, and perform early warning analysis of the monitoring data.

7. The monitoring system for monitoring tangential relative deformation of structural interfaces according to claim 6, characterized in that: The signal conditioning module also includes a temperature compensation circuit, which has a built-in thermistor (23). The thermistor (23) is located near the LVDT coil assembly (2) and is used to compensate for the measurement drift of the LVDT coil assembly (2) caused by temperature changes. The standardized electrical signal output by the signal conditioning module is a 4-20mA current signal or an RS-485 digital signal.

8. The monitoring system for monitoring tangential relative deformation of structural interfaces according to claim 6, characterized in that: The data acquisition terminal includes a multi-channel high-precision acquisition module with a sampling rate of no less than 200Hz per channel and an analog-to-digital conversion resolution of no less than 16 bits. The data acquisition terminal is also equipped with a local storage module and a wireless communication module, supporting three working modes: timed acquisition, triggered acquisition, and real-time continuous acquisition.

9. The monitoring system for monitoring tangential relative deformation of structural interfaces according to claim 6, characterized in that: The data processing and analysis module, according to The tangential relative displacement of the interface is calculated, where ΔL1 and ΔL2 are the linear displacements of the transverse rack push rod A (7) and the transverse rack push rod B (8), respectively. The linear displacements are obtained by conversion based on the transmission ratio of the transmission gear set (11) and the axial displacement of the LVDT core (3).

10. The monitoring system for monitoring tangential relative deformation of structural interfaces according to claim 6, characterized in that: The data processing and analysis module has a built-in temperature drift compensation algorithm and a gear tooth backlash error compensation algorithm to correct errors in the measurement results; the data processing and analysis module also has a multi-level threshold alarm function to issue different levels of early warning signals in real time based on the relative tangential displacement of the interface.

Images