Intelligent main cable built-in sensing optical fiber leading-out device and sensing optical fiber replacement method

Abstract

The invention discloses an intelligent main cable built-in sensing optical fiber leading-out device and a sensing optical fiber replacement method, a sensing optical fiber is arranged in a main cable, two ends of the sensing optical fiber are arranged between adjacent cable clamps of the main cable, the sensing optical fiber is connected with a leading-out device, and the leading-out device comprises an in-out guide piece and a sealing box. The in-out guide piece leads out the sensing optical fiber from the interior of the main cable and protects the sensing optical fiber from being extruded by parallel steel wires in the main cable; the parallel steel wires in the main cable are exposed at the inlet and outlet guide part, and a sealing box is arranged on the outer side of the exposed position and used for solving the corrosion prevention problem of the parallel steel wires at the exposed position. The sensing optical fiber penetrates out of a through hole in the sealing box and is selectively connected with the signal modulator or the traction replacement assembly. When the sensing optical fiber is replaced, a traction replacement assembly is installed on the outer side of each leading-out device, one end pulls an old sensing optical fiber, and the other end synchronously releases a new sensing optical fiber. The problem that the sensing optical fiber cannot be replaced under normal service of the main cable is solved, and the replacement method is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge cables, and in particular relates to an intelligent main cable built-in sensing optical fiber lead-out device and a sensing optical fiber replacement method. Background Art

[0002] The cable system is the key load-bearing component of a suspension bridge, including: main cables, suspenders, loose cable saddles, main cable saddles, anchoring systems, etc. Among them, the main cable is the main load-bearing component of the suspension bridge. It bears the main tension and is also called the "lifeline" of the suspension bridge. The main cable is irreplaceable throughout the life cycle of the bridge, and its design life is required to reach more than one hundred years.

[0003] Due to the effects of rain, snow, and temperature fluctuations, water vaporizes and liquefies around and within the main cable, causing corrosion. This is especially true at the lowest point of the main cable, where gravity accumulates moisture, making rust more likely. Rust can directly impact the safety of the main cable, so it is crucial to monitor humidity changes and promptly dehumidify any detected humidity changes.

[0004] Regarding temperature issues, the main cable is subject to constant changes in environmental factors, and its temperature field is constantly changing. The linear shape and internal forces of the main cable strands are very sensitive to temperature changes. In addition, temperature changes will cause changes in cable tension, which in turn will cause changes in the linear shape of the main cable. At the same time, temperature changes will cause changes in the elevation and displacement of the tower top, which in turn affect the linear shape and internal forces of the main cable. Therefore, monitoring the main cable temperature is very important, and any abnormal temperature needs to be addressed immediately.

[0005] However, due to the large diameter of the main cable and the complex construction environment, it is difficult to sense the temperature and humidity inside it. Generally, the fiber grating is easily damaged and cannot be replaced after damage. The Chinese invention patent with application number 2022103726700 discloses a smart cable for bridges that can self-sensing the temperature inside the cable. It is specifically disclosed that it is composed of temperature measuring strands and parallel steel wires. The temperature measuring strands are located at at least one of the center position, the sub-center position and the outer edge position on the cable cross section. That is, the temperature measuring strands are used instead of parallel steel wires, which solves the problem of temperature and humidity monitoring. However, due to the limited life of the temperature measuring strand sensor, it needs to be replaced frequently. However, the above patent cannot solve the major problem of needing to replace it in the later stage. The Chinese invention patent with application number 2024100072427 discloses a full-area temperature and humidity monitoring system and monitoring method for the main cable of a suspension bridge, which also does not solve the problem of replacing sensors. Chinese invention patent application number 2024117171947 discloses a replaceable structure and replacement method for a cable-mounted, replaceable temperature, humidity, and vibration sensing optical cable. However, this method does not involve a cable-mounted sensor fiber extraction device, making it impossible to replace the sensor fiber while the cable is operating. Therefore, it is not feasible in engineering practice. Chinese invention patent application number 202411910851X discloses a structure and method for installing a built-in suspension bridge sensor fiber for the main cable of a suspension bridge. This method replaces the sensor fiber by placing replacement devices in the anchor chambers and saddles at both ends of the main cable. However, this method allows the sensor fiber to be extracted only at the main cable saddle or anchorage on the tower. First, these locations have complex structures, making extraction difficult. Second, the sensor fiber is very long, making it difficult to implement in actual engineering. Third, the sensor fiber lacks effective protection at the tower and anchorage, posing challenges to its safety and durability.

[0006] In summary, it is currently difficult to replace the damaged sensing optical fiber in the main beam, and the existing replacement method is difficult to implement in actual projects.

[0007] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0008] The present invention aims to provide an intelligent main cable built-in sensing fiber lead-out device and a sensing fiber replacement method. This device leads the sensing fiber inside the main cable through an access guide, enabling free replacement of the sensing fiber. A sealing box seals the exposed portion of the main cable at the access guide to prevent corrosion of the parallel steel wires in the exposed portion of the main cable after the access guide is installed. A sensing fiber replacement method based on the lead-out device is also proposed to enable replacement of the sensing fiber inside the main cable. Using this lead-out device and replacement method, the sensing fiber inside the main cable is installed in sections on the main cable through the access guide, making the replacement method simple and efficient, solving the problem of sensor fiber replacement.

[0009] The technical solution adopted by the present invention is: an intelligent main cable built-in sensing optical fiber lead-out device, comprising a main cable, wherein the main cable is provided with a sensing optical fiber and parallel steel wires;

[0010] The sensing optical fiber is arranged axially along the main cable, and a cable clamp is provided on the main cable. The two ends of the sensing optical fiber are respectively arranged between two adjacent cable clamps on the main cable. The sensing optical fiber is connected to a set of lead-out devices, which include an entry and exit guide and a sealing box; the entry and exit guide is used to lead the sensing optical fiber out from the inside of the main cable, and at the same time protect the sensing optical fiber from being squeezed, deformed and damaged by the parallel steel wires.

[0011] The entry and exit guide leads the sensing optical fiber out from the inside of the main cable; the parallel steel wires in the main cable form an avoidance gap along the surface of the entry and exit guide; the parallel steel wires inside the main cable in a length range of 100 to 400 mm at the avoidance gap are exposed, and a sealing box is provided on the outside to solve the corrosion problem of the parallel steel wires in the main cable.

[0012] Preferably, the sensing optical fiber is arranged inside the main cable along the axis of the main cable. Based on the differences in temperature and humidity in different areas inside the main cable, the sensing optical fiber is strategically arranged. The preferred positions include the center, edge and 1 / 2 radius of the main cable, so as to separately monitor the temperature and humidity changes in different areas inside the main cable.

[0013] Preferably, the inlet and outlet guide of the lead-out device includes an inlet and outlet guide tube, a reinforcing mesh tube, and a threading hole. The inlet and outlet guide tube has an inner and outer double-layer structure. The inner layer is made of a high-strength material with a yield strength sufficient to protect the sensing optical fiber from being squeezed and damaged by the main cable steel wire. The outer layer is made of a flexible, high-toughness material that, through its own deformation ability, avoids affecting the stress-bearing properties of the parallel steel wires. The high-strength material includes any one of mild steel, titanium alloy, or silicon carbide reinforced metal matrix composite material, preferably titanium alloy. The flexible, high-toughness material includes any one of ceramic silicone rubber, shape memory alloy, or high-molecular polyethylene, preferably shape memory alloy. The inner diameter of the threading hole is larger than the outer diameter of the sensing optical fiber, and a reinforcing mesh tube is fixedly installed in the threading hole. The sensing optical fiber passes through the reinforcing mesh tube. The inner wall of the reinforcing mesh tube is polished material to reduce friction between the inner wall of the reinforcing mesh tube and the sensing optical fiber, thereby preventing breakage during sensor fiber replacement. The inlet and outlet guide adapts to the internal configuration of the main cable and has a cross-sectional shape of either a shuttle or an elliptical shape, preferably an elliptical shape.

[0014] Preferably, the sealing box of the lead-out device is arranged at the position where the parallel steel wires are exposed in the avoidance gap, is fixedly connected to the surface of the main cable, and completely wraps the exposed parallel steel wires in the main cable. A rubber sealing layer is provided on the contact surface with the main cable. A closed space is formed between the sealing box and the main cable by the rubber sealing layer, which meets the sealing requirements for main cable anti-corrosion in existing national standards, protects the parallel steel wires, and prevents them from being corroded.

[0015] The material of the sealing box includes one of stainless steel, aluminum alloy, and fiber-reinforced composite material to prevent the sealing box itself from being corroded. The cross-sectional form includes one of circular and rectangular; preferably rectangular, providing a working plane for external equipment.

[0016] An observation window is provided on one side of the sealed box wall to facilitate observation of the status of the parallel steel wires inside, and a through hole is provided on the other side of the box wall. A sealing limit sleeve is provided in the through hole to prevent corrosive media from entering the sealed box through the through hole. The sensing optical fiber extends from the inside of the main cable into the sealed box through the entry and exit guide, and is led out to the outside of the sealed box through the sealing limit sleeve; the outside of the sealed box is equipped with different equipment according to different working states: when in service, a modulator and an Internet of Things module are installed outside the sealed box, the led-out sensing optical fiber is connected to the modulator, and the modulator is connected to the Internet of Things module; the modulator and the Internet of Things module are powered by solar batteries to ensure uninterrupted operation of the modulator and the Internet of Things module; when in replacement state, the modulator and the Internet of Things module are disconnected from the sensing optical fiber and then connected to the pulling and replacing assembly arranged outside the sealed box, which includes a winch and a servo motor.

[0017] Preferably, a sealing gasket is fixedly connected to the inner wall of the sealing and limiting sleeve, an air storage tank is defined within the sealing and limiting sleeve, a compression piston ring is threadedly connected to the air storage tank, and a plurality of connecting air pipes are connected between the air storage tank and the sealing gasket. By rotating the compression piston ring, the sealing gasket is controlled to contract, thereby closing or opening the through hole.

[0018] Preferably, temperature gratings and humidity gratings are provided at intervals on the sensing optical fiber to measure the internal temperature and humidity at different locations of the main cable. Preferably, a polyimide humidity-sensitive sleeve is directly attached to the outside of the humidity grating to significantly improve the measurement sensitivity and accuracy of the humidity sensor by increasing the thickness of the humidity-sensitive material. Preferably, a rigid protective sleeve is provided on the outside of the temperature grating to isolate stress; a rigid protective sleeve with vents is provided on the outside of the humidity grating to isolate stress and allow humid air to enter and contact the humidity-sensitive grating. A plurality of tensile strength wires are provided on the outside of the sensing optical fiber; a spiral armor tube is provided on the outside of the sensing optical fiber and the tensile strength wires to protect the sensing optical fiber from being squeezed and damaged by the parallel steel wires, while providing space for the sensing optical fiber to ensure replacement of the sensing optical fiber. The portion of the sensing optical fiber where the temperature grating and humidity grating are not provided is connected to the tensile strength wire by resin to form a bonding portion to increase the strength of the sensing optical fiber and prevent it from breaking during replacement.

[0019] The method for replacing a sensing optical fiber using the above-mentioned intelligent main cable built-in sensing optical fiber lead-out device comprises the following steps:

[0020] Step 1. Disconnect:

[0021] The old sensing fiber is replaced before, and the new sensing fiber is replaced after. Rotate the sealing limit sleeve on the sealing box to open the through hole and disconnect the old sensing fiber from the modulator outside the sealing box.

[0022] Step 2: Connect the old and new optical fibers:

[0023] The pulling replacement assembly is divided into a first pulling replacement assembly and a second pulling replacement assembly. The old sensing optical fiber and one end of the tensile wire are wound on the winch of the first pulling replacement assembly and anti-slip treatment is applied. The new sensing optical fiber and the tensile wire are wound on the winch of the second pulling replacement assembly. Sufficient overlap length is reserved for the new and old optical fibers. UV curable resin is coated at the overlap and irradiated with UV light to form a cured resin joint.

[0024] Step 3: Synchronous pulling:

[0025] The servo motors at both ends are started, and the winding and releasing are controlled and synchronized by adjusting the servo motor speed, allowing the new sensing optical fiber to enter the main cable along the entry and exit guides. During the pulling process, the servo motor speed of the second pulling and replacement assembly is adjusted to be slightly higher than the servo motor speed of the first pulling and replacement assembly to ensure that the sensing optical fiber is always in a relaxed state during the pulling process. At the same time, a torque sensor is used to monitor the output torque of the servo motor. When the output torque of the servo motor exceeds the preset threshold, the rotation of the servo motors at both ends is stopped, and manual maintenance and troubleshooting are carried out to avoid damage to the sensing optical fiber.

[0026] Step 4: Cut the sensing fiber:

[0027] When the cured resin joint reaches the first pulling replacement component position, stop pulling, reserve sufficient length of sensing fiber and tensile wire outside the sealing box, and use pliers to cut the new sensing fiber and tensile wire from the cured resin joint; then peel off the sensing fiber and tensile wire at the cross section, and trim the sensing fiber cross section with optical fiber cutters to ensure the normal use of the new sensing fiber;

[0028] Step 5: System recovery:

[0029] Connect the new sensing optical fiber to the modulator, test and calibrate the new sensing optical fiber, rotate the sealing limit sleeve on the sealing box in the opposite direction to close the through hole, and the replacement is completed.

[0030] Preferably, when replacing, first weld a section of positioning optical fiber at the outlet end of the old sensing optical fiber, and use a demodulation device to accurately measure the distance between the first sensing grid point on the old sensing optical fiber and a known reference point, thereby marking the exact position of the first sensing grid point; after replacing the new optical fiber sensor, use the same method as above to mark the position of its first sensing grid point; then, through pulling adjustment, make the positions of the first sensing grid points of the new and old optical fibers coincide, and the in-situ replacement of the sensing optical fiber can be achieved.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. By installing access guides on the main cable, the internal sensing optical fiber of the main cable is led out, making the internal sensing optical fiber of the main cable replaceable, solving the problem of the sensor optical fiber being unable to be replaced, and realizing the monitoring of the temperature and humidity inside the main cable throughout the life cycle of the suspension bridge;

[0033] 2. By setting up entry and exit guides on the main cable, the laying length of the sensing optical fiber can be adjusted. It can be laid out in multiple sections according to actual needs, reducing the laying length of each section of the sensing optical fiber. The optical fiber can be replaced section by section, reducing the cost of replacing the sensing optical fiber.

[0034] 3. Seal the exposed parts of the main cable steel wires through the sealing box and the sealing limit sleeve to prevent water vapor from corroding the exposed parallel steel wires;

[0035] 4. The tensile strength of the sensing optical fiber is improved by bonding the tensile wire and the sensing optical fiber, and the spiral armored tube is used for protection, which greatly avoids damage during transportation, installation, and operation;

[0036] 5. Use solar batteries and Internet of Things modules to transmit the working status of the sensor fiber in real time, ensuring that the sensor fiber can be replaced in time if damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a built-in sensing optical fiber lead-out device for an intelligent main cable according to an embodiment of the present invention;

[0038] Figure 2 This is a cross-sectional view of the main cable in an embodiment of the present invention;

[0039] Figure 3 This is a structural diagram of a main cable assembly entry and exit guide in an embodiment of the present invention;

[0040] Figure 4 A partial cross-sectional view of a main cable assembly entry and exit guide in an embodiment of the present invention;

[0041] Figure 5 This is a schematic structural diagram of the sealed box in service state according to an embodiment of the present invention;

[0042] Figure 6 This is a cross-sectional view of the structure of the sealed box in the service state according to the embodiment of the present invention;

[0043] Figure 7 This is a cross-sectional view of the structure of the sealing box in the replacement state according to an embodiment of the present invention;

[0044] Figure 8 Schematic diagram of the structure of the entry and exit guide in an embodiment of the present invention;

[0045] Figure 9 is a cross-sectional view of an entry and exit guide member according to an embodiment of the present invention;

[0046] Figure 10 is a cross-sectional view of an entry and exit guide member according to an embodiment of the present invention;

[0047] Figure 11 for Figure 7 Schematic diagram of the structure at A in FIG;

[0048] Figure 12 Schematic diagram of the sealing and limiting sleeve structure in an embodiment of the present invention;

[0049] Figure 13 Schematic diagram of the sensing optical fiber and the tensile wire in an embodiment of the present invention;

[0050] Figure 14This is a cross-sectional view of the sensing optical fiber, tensile wire, and spiral armor tube in an embodiment of the present invention;

[0051] Description of main reference numerals:

[0053] 1-Main cable, 11-Sensing optical fiber, 114-Spiral armored tube, 111-Temperature grating, 112-Humidity grating, 113-Tensile wire, 115-Adhesive part, 11a-Old sensing optical fiber, 11b-New sensing optical fiber, 12-Parallel steel wires, 13-Avoidance gap, 2-Entry and exit guide, 21-Entry and exit guide tube, 22-Reinforced mesh tube, 23-Threading hole, 3-Sealing box, 31-Through hole, 32-Sealing limit sleeve, 321-Sealing gasket, 322-Air storage tank, 323-Compression piston ring, 324-Connecting air pipe, 33-Rubber sealing layer, 34-Observation window, 4-Pulling replacement assembly, 4a First pulling replacement assembly, 4b Second pulling replacement assembly, 41-Winch, 42-Servo motor, 5-Modulator, 6-Internet of Things module, 7-Solar battery, 8-Cable clamp, 9 Curing resin joint. DETAILED DESCRIPTION

[0054] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0055] Figure 1 This is an intelligent main cable with built-in sensing fiber in the embodiment of the present invention, which is applied to a large-span suspension bridge. The main cable 1 has a diameter of 1000mm and a total length of 2500m. The sensing fiber 11 is laid at the bottom of the suspension section of the main cable 1. The laying length of the sensing fiber 11 is 160m. Specifically, Figure 2 As shown, the sensing optical fibers 11 are respectively arranged at the center, edge and half radius of the main cable 1 to perform multi-directional temperature and humidity detection.

[0056] like Figure 1-Figure 4 Figure 2 shows an intelligent main cable internal sensing fiber extraction device according to an embodiment of the present invention. Installed on main cable 1, the device is positioned between two adjacent cable clamps 8, spaced 16 meters apart. It is used to replace sensing fibers 11 within main cable 1. The extraction device includes entry and exit guides 2 and a sealing box 3. Each sensing fiber 11 is provided with entry and exit guides 2 at both ends, allowing it to be extracted from the interior of main cable 1. Parallel steel wires 12 in main cable 1 are formed with a clearance gap along their surface. This clearance gap 13 extends 300 mm, exposing only the exposed parallel steel wires 12. A sealing box 3 is located on the outside of the clearance gap.

[0057] In this embodiment, sensing fibers 11 are also deployed between the anchors on both sides of the suspension bridge and the cable saddles, and between the cable saddles and the bottom of the main cable suspension section. Each segment of sensing fiber 11 is connected to an access guide 2 at both ends, preventing interference between the two segments and independently monitoring temperature and humidity. If a segment of sensing fiber 11 is damaged, only the damaged segment needs to be replaced. The segmented, adjustable length of the sensing fiber 11 eliminates the need for a continuous length, reducing the length of each segment and allowing for segment-by-segment replacement, thus reducing the cost of replacing the sensing fiber.

[0058] like Figure 5-Figure 7 The figure shows the sealing box 3 in the embodiment of the present invention. The sealing box 3 is made of 316L austenitic stainless steel, and its dimensions are: length × width along the main cable section = 1200 × 1200 mm, and 500 mm in length along the main cable axis. The sealing box 3 is anti-corrosive treated, and the inner and outer surfaces are electropolished, with a passivation film thickness of ≥15 nm. A rubber sealing layer 33 is provided on the contact surface between the sealing box 3 and the main cable 1. An observation window 34 is provided on one side of the box wall of the sealing box 3, which is made of a polycarbonate optical grade sheet with a thickness of 10 mm, a transmittance of >92%, and a UV coating, and is sealed with a butyl rubber gasket; a through hole 31 is provided on the other side of the box wall of the sealing box 3, and a sealing limit sleeve 32 is provided in the through hole 31.

[0059] like Figure 6 and Figure 7 The figures show the structure of the sealing box 3 in the service state and the replacement state, respectively, according to an embodiment of the present invention. In the service state, the sensing optical fiber 11 is connected to the modulator 5, which is in turn connected to the Internet of Things module 6. The modulator 5 uploads the information monitored by the sensing optical fiber 11 and the operating status of the sensing optical fiber 11 via the Internet of Things module 6. The solar battery 7 powers the modulator 5 and the Internet of Things module 6, ensuring their uninterrupted operation and enabling maintenance personnel to promptly replace damaged sensing optical fiber 11. In the replacement state, the modulator 5 and the Internet of Things module 6 are disconnected from the sensing optical fiber 11, and maintenance personnel carry the pull-and-replace assembly 4 to replace the sensing optical fiber 11.

[0060] Specifically, the pulling and replacing assembly 4 includes a winch 41 and a servo motor 42. In the replacement state, both ends of the sensing optical fiber 11 are provided with a pulling and replacing assembly 4, wherein the old sensing optical fiber 11a is wound around the winch 41 at one end, and the new sensing optical fiber 11b is wound around the winch 41 at the other end, and the old sensing optical fiber 11a and the new sensing optical fiber 11b are bonded. By controlling the synchronous operation of the servo motors 42 at both ends to drive the two winches 41 to rotate, the winch 41 can pull one end of the old sensing optical fiber 11a during the rotation process, while the winch 41 at the other end is controlled by the servo motor 42 to synchronously release the new sensing optical fiber 11b. During the winding process, the old sensing optical fiber 11a pulls the new sensing optical fiber 11b back into the main cable 1 until it completely replaces the old sensing optical fiber 11a. The servo motor 42 is equipped with a torque sensor, which controls the pulling force on the sensing optical fiber 11 by detecting the output torque of the servo motor 42, thereby preventing the sensing optical fiber 11 from being broken.

[0061] like Figures 8 to 10 The figure shows a schematic diagram of the entry and exit guide 2 in an embodiment of the present invention. The main body of the entry and exit guide 2 is an entry and exit guide tube 21. The inner layer of the entry and exit guide tube 21 is made of TC4 titanium alloy with a wall thickness of 1.5mm, and the outer layer is made of nickel-titanium shape memory alloy. The inner wall surface of the entry and exit guide tube 21 is electrolytically polished, and the outer layer is micro-arc oxidized. The entry and exit guide 2 adopts an elliptical cross-section with a major axis of 15mm and a minor axis of 6mm, and the major axis is parallel to the main cable axis. The reinforcing mesh tube 22 is made of 316L stainless steel woven mesh (wire diameter Φ0.1mm, mesh number 120) and is ultrasonically welded to the inner wall of the guide tube, and is mirror-polished with an electrolyte. There is a threading hole 23 inside the entry and exit guide 2, and the threading hole 23 has an aperture of 2.4mm and a chamfer of C0.2 at both ends.

[0062] like Figure 11 and Figure 12 The figure shows a schematic diagram of the structure of the sealing limiting sleeve 32 in an embodiment of the present invention. The sealing limiting sleeve 32 is arranged at the opening of the sealing box 3, and an air storage tank 322 is provided inside. A compression piston ring 323 is threadedly connected to the air storage tank 322, and a plurality of connecting air pipes 324 are connected between the air storage tank 322 and the sealing gasket 321. When in service, the air in the air storage tank 322 is compressed into the sealing gasket 321 along the connecting air pipe 324 by rotating the compression piston ring 323 to expand it, thereby sealing and limiting the sensing optical fiber 11 to prevent water vapor from entering the sealing box 3. When in replacement, the air in the sealing gasket 321 is returned to the air storage tank 322 along the connecting air pipe 324 by rotating the compression piston ring 323 in the opposite direction, so that the sensing optical fiber 11 can be replaced.

[0063] like Figure 13 and Figure 14Figure 1 shows a schematic diagram of the sensing fiber, tensile wire, and spiral armor tube in an embodiment of the present invention. The sensing fiber 11 has a diameter of 0.8 mm and is provided with a temperature grating 111 and a humidity grating 112. Multiple tensile wires 113 are located on the outside of the sensing fiber 11, each with a diameter of 0.5 mm. A spiral armor tube 114 is located outside the sensing fiber 11 and the multiple tensile wires 113, with an outer diameter of 5.8 mm and an inner diameter of 4.8 mm. This provides sufficient channel capacity for replacement of the sensing fiber 11.

[0064] Specifically, the tensile wire 113 is made of aramid fiber, which provides ultra-high tensile strength and can also serve as a buffer material to protect the sensing optical fiber 11. During the replacement process, it can serve as the main tensile reinforcement of the optical fiber bundle, bearing most of the tension and protecting the temperature grating 111 and humidity grating 112. The remaining specific parameters of the sensing optical fiber 11 and the tensile wire 113 are shown in the following table:

[0065]

[0066]

[0067] In this embodiment of the present invention, the portion of the sensing optical fiber 11 not provided with the temperature grating 111 and the humidity grating 112 is effectively connected to the corresponding portion of the tensile wires 113 via resin to form a bonding portion 115. Four tensile wires 113 are bonded to the outside of the sensing optical fiber 11. The sensing optical fiber 11 and the four tensile wires 113 share the load, preventing the sensing optical fiber 11 from breaking under tension during replacement and also preventing damage from friction between the sensing optical fiber 11 and the spiral armor tube 114 during replacement. In another embodiment of the present invention, multiple tensile wires 113 are braided diagonally around the outside of the sensing optical fiber 11 to form a porous mesh protective sheath, thereby increasing the tensile strength of the sensing optical fiber 11 and preventing damage during replacement.

[0068] The method for replacing a sensing optical fiber using the intelligent main cable built-in sensing optical fiber lead-out device of the present invention comprises the following steps:

[0069] Step 1. Disconnect:

[0070] The sensing optical fiber 11 is replaced with the old sensing optical fiber 11a. The sensing optical fiber 11 is replaced with the new sensing optical fiber 11b. The sealing limit sleeve 32 on the sealing box 3 is rotated to open the through hole 31, and the connection between the old sensing optical fiber 11a and the modulator 5 outside the sealing box 3 is disconnected.

[0071] Step 2: Connect the old and new optical fibers:

[0072] The pulling replacement assembly 4 is divided into a first pulling replacement assembly 4a and a second pulling replacement assembly 4b. The old sensing optical fiber 11a and one end of the tensile wire 113 are wound on the winch 41 of the first pulling replacement assembly 4a and anti-slip treatment is performed. The new sensing optical fiber 11b and the tensile wire 113 are wound on the winch 41 of the second pulling replacement assembly 4b. Sufficient overlap length is reserved for the new and old optical fibers. UV curable resin is coated at the overlap, and UV lamp irradiation is used to form a cured resin joint 9.

[0073] Step 3: Synchronous pulling:

[0074] The servo motors 42 at both ends are started, and the speed of the servo motors 42 is adjusted to control the synchronization of reeling and releasing, so that the new sensing optical fiber 11b enters the main cable 1 along the entry and exit guide 2; during the pulling process, the speed of the servo motor 42 of the second pulling and replacing assembly 4b is adjusted to be slightly greater than the speed of the servo motor 42 of the first pulling and replacing assembly 4a, to ensure that the sensing optical fiber is always in a relaxed state during the pulling process; at the same time, a torque sensor is used to monitor the output torque of the servo motor. When the output torque of the servo motor exceeds a preset threshold, the rotation of the servo motors 42 at both ends is stopped, and manual maintenance and troubleshooting are performed to avoid damage to the sensing optical fiber;

[0075] Step 4: Cut the sensing fiber:

[0076] When the cured resin joint 9 reaches the position of the first pulling replacement assembly 4a, the pulling is stopped, and sufficient lengths of the sensing optical fiber 11 and the tensile strength wire 113 are reserved outside the sealing box 3. The new sensing optical fiber 11b and the tensile strength wire 113 are cut off from the cured resin joint 9 with a pair of pliers; then the sensing optical fiber 11 and the tensile strength wire 113 at the cross section are peeled off, and the sensing optical fiber cross section is trimmed with an optical fiber cutter to ensure the normal use of the new sensing optical fiber 11b;

[0077] Step 5: System recovery:

[0078] Connect the new sensing optical fiber 11b to the modulator 5, detect and calibrate the new sensing optical fiber 11b, and reversely rotate the sealing limit sleeve on the sealing box to close the through hole, and the replacement is completed.

[0079] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An intelligent main cable built-in sensing optical fiber lead-out device, characterized in that: It comprises a main cable (1), wherein a sensing optical fiber (11) and parallel steel wires (12) are provided inside the main cable (1); The sensing optical fiber (11) is arranged axially along the main cable (1), a cable clamp (8) is provided on the main cable (1), two ends of the sensing optical fiber (11) are respectively arranged between two adjacent cable clamps (8) on the main cable (1), and the sensing optical fiber (11) is connected to a set of lead-out devices, which include an inlet and outlet guide (2) and a sealing box (3); The entry and exit guide (2) leads the sensing optical fiber (11) out from the inside of the main cable (1); the parallel steel wires (12) in the main cable (1) form an avoidance gap (13) along the surface of the entry and exit guide (2); the parallel steel wires (12) in the main cable (1) within a length range of 100 to 400 mm at the avoidance gap (13) are exposed, and a sealing box (3) is provided on the outside.

2. The intelligent main cable built-in sensing optical fiber lead-out device according to claim 1, characterized in that: The sensor optical fiber (11) is arranged at the center, edge and half radius of the main cable.

3. The intelligent main cable built-in sensing optical fiber lead-out device according to claim 2, characterized in that: The inlet and outlet guide member (2) of the lead-out device comprises an inlet and outlet guide tube (21), a reinforcing net cylinder (22) and a threading hole (23); The entry and exit guide tube (21) is a double-layer structure with inner and outer layers, the inner layer is made of high-strength material, the high-strength material includes any one of mild steel, titanium alloy or silicon carbide reinforced metal matrix composite material, and the outer layer is made of flexible high-toughness material, the flexible high-toughness material includes any one of ceramic silicone rubber, shape memory alloy or high molecular polyethylene; the inner diameter of the threading hole (23) is larger than the outer diameter of the sensing optical fiber (11), and a reinforcing mesh tube (22) is fixedly assembled in the threading hole (23), and the inner wall of the reinforcing mesh tube (22) is made of polished material; the entry and exit guide member (2) is adapted to the internal configuration of the main cable (1), and its cross-section is one of a shuttle shape and an elliptical shape.

4. The intelligent main cable built-in sensing optical fiber lead-out device according to claim 3, characterized in that: The sealing box (3) of the lead-out device is arranged at the exposed position of the parallel steel wire (12) at the avoidance gap (13), fixedly connected to the surface of the main cable (1), and a rubber sealing layer (33) is provided on the contact surface with the main cable (1); The sealing box (3) is made of a material including stainless steel, aluminum alloy, or fiber-reinforced composite material, and has a cross-sectional shape including a circular shape or a rectangular shape. The sealing box (3) is provided with an observation window (34) on one side of the box wall, and a through hole (31) is provided on the other side of the box wall. A sealing limit sleeve (32) is provided in the through hole (31). The sensing optical fiber (11) extends from the inside of the main cable (1) to the inside of the sealing box (3) through the entry and exit guide (2), and passes through the sealing limit sleeve (32) to be led out to the outside of the sealing box (2); when in service state, the sensing optical fiber (11) is connected to the modulator (5), the modulator (5) is connected to the Internet of Things module (6), and the modulator (5) and the Internet of Things module (6) are powered by a solar battery (7); when in replacement state, the sensing optical fiber (11) is connected to the pulling and replacing component (4), and the pulling and replacing component (4) includes a winch (41) and a servo motor (42).

5. The intelligent main cable built-in sensing optical fiber lead-out device according to claim 4, characterized in that: A sealing gasket (321) is fixedly connected to the inner wall of the sealing limiting sleeve (32), an air storage tank (322) is provided in the sealing limiting sleeve (32), a compression piston ring (323) is threadedly connected in the air storage tank, and a plurality of connecting air pipes (324) are connected between the air storage tank and the sealing gasket.

6. The intelligent main cable built-in sensing optical fiber lead-out device according to claim 5, characterized in that: Temperature gratings (111) and humidity gratings (112) are arranged at intervals on the sensing optical fiber (11); a polyimide humidity-sensitive sleeve is directly attached to the outside of the humidity grating (112); a rigid protective sleeve is arranged outside the temperature grating (111); and a rigid protective sleeve with vent holes is arranged outside the humidity grating (112); a plurality of tensile strength wires (113) are arranged outside the sensing optical fiber (11); spiral armor tubes (114) are arranged outside the sensing optical fiber (11) and the tensile strength wires (113); and a portion of the sensing optical fiber (111) where the temperature grating (111) and the humidity grating (112) are not arranged is connected to the tensile strength wires (113) by resin to form a bonding portion (115).

7. A method for replacing a sensing optical fiber using the intelligent main cable built-in sensing optical fiber lead-out device according to claim 1, 2, 3, 4, 5 or 6, characterized in that: The following steps are involved: Step 1. Disconnect: Before the sensing optical fiber (11) is replaced, it is the old sensing optical fiber (11a). After the sensing optical fiber (11) is replaced, it is the new sensing optical fiber (11b). The sealing limiting sleeve (32) on the sealing box (3) is rotated to open the through hole (31), and the connection between the old sensing optical fiber (11a) and the modulator (5) outside the sealing box (3) is disconnected. Step 2: Connect the old and new optical fibers: The pulling replacement assembly (4) is divided into a first pulling replacement assembly (4a) and a second pulling replacement assembly (4b). The old sensing optical fiber (11a) and one end of the tensile strength wire (113) are wound on the hoist (41) of the first pulling replacement assembly (4a) and anti-slip treatment is performed. The new sensing optical fiber (11b) and the tensile strength wire (113) are wound on the hoist (41) of the second pulling replacement assembly (4b). Sufficient overlapping length is reserved for the new and old optical fibers. Ultraviolet curing resin is coated on the overlapping portion, and ultraviolet light is used to irradiate the overlapped portion to form a cured resin joint (9). Step 3: Synchronous pulling: The servo motors (42) at both ends are started, and the reeling and releasing are controlled to maintain synchronization by adjusting the rotation speed of the servo motors (42), so that the new sensing optical fiber (11b) enters the main cable (1) along the entry and exit guide (2); during the pulling process, the rotation speed of the servo motor (42) of the second pulling replacement component (4b) is adjusted to be slightly greater than the rotation speed of the servo motor (42) of the first pulling replacement component (4a), so as to ensure that the sensing optical fiber is always in a relaxed state during the pulling process; at the same time, a torque sensor is used to monitor the output torque of the servo motor. When it is detected that the output torque of the servo motor exceeds a preset threshold, the rotation of the servo motors (42) at both ends is stopped, and manual maintenance and troubleshooting are performed to avoid damage to the sensing optical fiber; Step 4: Cut the sensing fiber: When the solidified resin joint (9) reaches the position of the first pulling replacement component (4a), the pulling is stopped, and a sufficient length of the sensing optical fiber (11) and the tensile strength wire (113) is reserved outside the sealing box (3), and the new sensing optical fiber (11b) and the tensile strength wire (113) are cut off from the solidified resin joint (9) with a pair of pliers; then, the sensing optical fiber (11) and the tensile strength wire (113) at the cross section are peeled off, and the sensing optical fiber cross section is trimmed with an optical fiber cutter to ensure the normal use of the new sensing optical fiber (11b); Step 5: System recovery: Connect the new sensing optical fiber (11b) to the modulator (5), detect and calibrate the new sensing optical fiber (11b), and reversely rotate the sealing limit sleeve on the sealing box to close the through hole, and the replacement is completed.

8. The method for replacing a sensing optical fiber according to claim 7, wherein: When replacing, first, a section of positioning optical fiber is fused to the outlet end of the old sensing optical fiber (11a), and a demodulation device is used to accurately measure the distance between the first sensing grid point on the old sensing optical fiber (11a) and a known reference point, thereby marking the exact position of the first sensing grid point; After replacing the new optical fiber sensor (11b), the position of its first sensing grid point is marked using the same method as above; then, by pulling and adjusting, the positions of the first sensing grid points of the new and old optical fibers are made to coincide, thereby achieving in-situ replacement of the sensing optical fiber.

Images