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

Abstract

The application discloses a kind of intelligent main cable built-in sensing optical fiber lead-out device and sensing optical fiber replacement method, sensing optical fiber is arranged in main cable, sensing optical fiber both ends are arranged between adjacent cable clamp of main cable, connected with lead-out device, lead-out device includes access guide and sealing box, access guide leads sensing optical fiber from the inside of the main cable, protects sensing optical fiber from the inside of main cable parallel steel wire extrusion;Main cable is exposed inside parallel steel wire at the position of access guide, sealing box is equipped outside exposed position, to solve the anticorrosion problem of exposed parallel steel wire.Sensing optical fiber is worn out through the through hole on sealing box, selectively connects signal modulation instrument or pull replacement component.Sensing optical fiber is replaced, and pull replacement component is installed outside each lead-out device, one end is pulled to old sensing optical fiber, and the other end is synchronized to release new sensing optical fiber.The application solves the problem that sensing optical fiber cannot be replaced under normal service of main cable, and the replacement method is simple and efficient.

Description

Technical Field

[0001] This invention belongs to the field of bridge cable technology, specifically relating to an intelligent main cable built-in sensing optical fiber lead-out device and a method for replacing the sensing optical fiber. Background Technology

[0002] The cable system is a key load-bearing component of a suspension bridge, including: main cable, suspenders, cable saddles, main cable saddles, anchorage system, etc. Among them, the main cable is the main load-bearing component of the suspension bridge. It bears the main tensile force and is also known as the "lifeline" of the suspension bridge. The main cable is irreplaceable throughout the entire life cycle of the bridge, and its design life is required to be more than 100 years.

[0003] Due to the effects of rain and snow, as well as temperature differences causing water to vaporize and liquefy around and inside the main cable, corrosion can occur inside the cable, especially at its lowest point where gravity causes moisture to accumulate and corrosion is more likely. Corrosion directly affects the safety of the main cable, therefore monitoring humidity changes is crucial, and dehumidification should be carried out promptly upon detecting changes.

[0004] Regarding temperature issues, the main cable is constantly affected by changing environmental factors, resulting in a continuously altering temperature field. The cable strand alignment and internal forces are highly sensitive to temperature variations. Furthermore, temperature changes alter cable tension, which in turn changes the main cable alignment. Simultaneously, temperature changes also affect the tower's elevation and misalignment, which in turn influence the main cable's alignment and internal forces. Therefore, monitoring the main cable temperature is crucial, and any abnormalities must be addressed immediately.

[0005] However, due to the large diameter of the main cable and the complex construction environment, sensing its internal temperature and humidity is difficult. Fiber optic gratings are generally prone to damage and cannot be replaced once damaged. Chinese invention patent application number 2022103726700 discloses a smart bridge cable with self-sensing internal temperature, specifically composed of temperature-sensing strands and parallel steel wires. The temperature-sensing strands are located at least one of the following positions on the cable cross-section: the center, the secondary center, and the outer edge. This uses temperature-sensing strands instead of parallel steel wires, solving the temperature and humidity monitoring problem. However, because the temperature-sensing strand sensors have a limited lifespan, they need frequent replacement. This patent does not solve the significant problem of needing to replace them later. Chinese invention patent application number 2024100072427 discloses a full-area temperature and humidity monitoring system and method for the main cable of a suspension bridge, but it also fails to solve the problem of sensor replacement. Chinese invention patent application number 2024117171947 discloses a replaceable structure and replacement method for a cable-embedded replaceable temperature, humidity, and vibration sensing optical cable. However, this method does not involve a lead-out device for the sensing optical fiber on the cable, making it impossible to replace the sensing optical fiber while the cable is in operation, thus rendering it impractical in engineering. Chinese invention patent application number 202411910851X discloses a layout structure and method for an embedded sensing optical fiber in the main cable of a suspension bridge. This method replaces the sensing optical fiber by arranging replacement devices at the anchor chambers and saddles at both ends of the main cable. However, this method only allows the sensing optical fiber to be led out at the main cable saddle or anchorage of the tower. Firstly, these locations have complex structures, making it difficult to lead out the sensing optical fiber; secondly, the sensing optical fiber is very long, making it difficult to implement in actual engineering; and thirdly, the sensing optical 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 damaged optical fibers in the main control unit, and existing replacement methods are difficult to implement in actual engineering projects.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a device for leading out the built-in sensing fiber optic cable in an intelligent main cable and a method for replacing the sensing fiber optic cable. This device leads out the sensing fiber optic cable from inside the main cable through an inlet / outlet guide, enabling free replacement of the sensing fiber optic cable. A sealed box is used to seal the exposed portion of the main cable at the inlet / outlet guide to prevent corrosion of the parallel steel wires on the exposed portion of the main cable after the inlet / outlet guide is installed. Simultaneously, a method for replacing the sensing fiber optic cable based on the aforementioned leading-out device is proposed, enabling the replacement of the sensing fiber optic cable inside the main cable. With the aforementioned leading-out device and replacement method, the sensing fiber optic cable inside the main cable is segmented and installed on the main cable through the inlet / outlet guide, making the replacement method simple and efficient, and solving the problem of the inability to replace the sensing fiber optic cable.

[0009] The technical solution adopted in this invention is: a smart main cable built-in sensing optical fiber lead-out device, including a main cable, wherein the main cable is provided with sensing optical fiber and parallel steel wire;

[0010] The sensing optical fiber is arranged along the axial direction of the main cable. The main cable is equipped with cable clamps. The two ends of the sensing optical fiber are respectively set 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 inlet / outlet guide and a sealing box. The inlet / outlet guide is used to lead the sensing optical fiber out from inside the main cable, while protecting the sensing optical fiber from being squeezed, deformed and damaged by parallel steel wires.

[0011] The inlet / outlet guide leads the sensing optical fiber out from inside the main cable; the parallel steel wires in the main cable form a clearance gap along the surface of the inlet / outlet guide; the parallel steel wires inside the main cable are exposed within a length range of 100-400mm at the clearance gap, and a sealed box is provided on the outside to solve the corrosion problem of the parallel steel wires inside the main cable.

[0012] Preferably, the sensing optical fiber is arranged along the axis of the main cable inside the main cable. Based on the differences in temperature and humidity in different areas inside the main cable, the sensing optical fiber is strategically deployed. Preferred locations include the center, edge, and half-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 / outlet guide of the lead-out device includes an inlet / outlet guide tube, a reinforcing mesh tube, and a threading hole. The inlet / outlet guide tube has a double-layer structure. The inner layer is made of a high-strength material with sufficient yield strength to protect the sensing optical fiber from damage caused by the main cable steel wire. The outer layer is made of a flexible, high-toughness material, which avoids affecting the stress performance of the parallel steel wire through its own deformation capability. 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 ceramicized silicone rubber, shape memory alloy, or high molecular weight 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 inside the threading hole. The sensing optical fiber passes through the reinforcing mesh tube, and the inner wall of the reinforcing mesh tube is made of polished material to reduce friction between the inner wall of the reinforcing mesh tube and the sensing optical fiber, preventing breakage during the replacement of the sensing optical fiber. The inlet / outlet guide is adapted to the internal configuration of the main cable, and its cross-sectional shape is either spindle-shaped or elliptical, preferably elliptical.

[0014] Preferably, the sealing box of the lead-out device is located at the exposed position of the parallel steel wire in the clearance gap, and is fixedly connected to the surface of the main cable, enclosing all the exposed parallel steel wires inside the main cable. The contact surface with the main cable is provided with a rubber sealing layer. The sealing box and the main cable are sealed together by the rubber sealing layer to achieve a sealed space, which meets the sealing requirements for corrosion protection of the main cable in the existing national standards, protects the parallel steel wires, and prevents them from being corroded.

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

[0016] One side wall of the sealed enclosure is equipped with an observation window for easy observation of the internal parallel steel wires. The other side wall has a through hole with a sealing and limiting sleeve inside to prevent corrosive media from entering the enclosure. The sensing optical fiber extends from inside the main cable into the sealed enclosure via an inlet / outlet guide, passes through the sealing and limiting sleeve, and exits to the outside of the enclosure. Different equipment is installed outside the sealed enclosure depending on the operating state: In service, a modulator and an IoT module are installed outside the enclosure, with the extended sensing optical fiber connected to the modulator, which in turn connects to the IoT module. The modulator and IoT module are powered by a solar battery to ensure uninterrupted operation. During replacement, the modulator and IoT module are disconnected from the sensing optical fiber and then connected to a traction replacement assembly deployed on the outside of the sealed enclosure, 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, and an air storage groove is formed inside the sealing and limiting sleeve. A compression piston ring is threadedly connected to the air storage groove, and several connecting air pipes connect the air storage groove 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 and humidity gratings are installed at intervals on the sensing optical fiber to measure the internal temperature and humidity at different locations on the main cable. Preferably, a polyimide humidity-sensitive sleeve is directly bonded to the outside of the humidity grating; by increasing the thickness of the humidity-sensitive material, the measurement sensitivity and accuracy of the humidity sensor are significantly improved. Preferably, a rigid protective sleeve is installed outside the temperature grating to isolate stress; a rigid protective sleeve with vent holes is installed outside the humidity grating to isolate stress and allow humid air to enter the contact humidity-sensitive grating. Multiple tensile wires are provided on the outside of the sensing optical fiber; a spiral armor tube is provided outside the sensing optical fiber and the tensile wires to protect the sensing optical fiber from damage by parallel steel wire compression, and to provide space for replacement of the sensing optical fiber. The portions of the sensing optical fiber without temperature and humidity gratings are bonded to the tensile wires with resin to form an adhesive portion, thereby improving the strength of the sensing optical fiber and preventing breakage during replacement.

[0019] The method for replacing the sensor fiber using the aforementioned intelligent main cable built-in sensor fiber lead-out device includes the following steps:

[0020] Step 1, Disconnect:

[0021] Before the sensor fiber was replaced, it was the old sensor fiber. After the sensor fiber was replaced, it was the new sensor fiber. Rotate the sealing limit sleeve on the sealed box, open the through hole, and disconnect the old sensor fiber from the modulator outside the sealed box.

[0022] Step 2, Connecting the old and new fiber optic cables:

[0023] The traction replacement assembly is divided into a first traction replacement assembly and a second traction replacement assembly. The old sensing fiber and one end of the tensile wire are wound around the winch of the first traction replacement assembly and anti-slip treatment is applied. The new sensing fiber and tensile wire are wound around the winch of the second traction replacement assembly. Sufficient overlap length is reserved between the old and new fibers. UV-curable resin is applied to the overlap and UV lamp is used to form a cured resin joint.

[0024] Step 3, Synchronous Traction:

[0025] The servo motors at both ends are started, and the winding and unwinding are synchronized by adjusting the speed of the servo motors, allowing the new sensing fiber to enter the main cable along the inlet and outlet guides. During the pulling process, the speed of the servo motor of the second pulling replacement component is adjusted to be slightly greater than that of the servo motor of the first pulling replacement component, ensuring that the sensing fiber remains in a slack state during the pulling process. At the same time, a torque sensor is used to monitor the output torque of the servo motors. When the output torque of the servo motors exceeds the preset threshold, the rotation of the servo motors at both ends is stopped, and manual inspection and troubleshooting are performed to avoid damage to the sensing fiber.

[0026] Step 4: Cut the sensing fiber:

[0027] When the cured resin connector reaches the first pull replacement component position, stop pulling. Leave a sufficient length of sensing fiber and tensile wire outside the sealed box, and use pliers to cut the new sensing fiber and tensile wire from the cured resin connector. Then, peel off the sensing fiber and tensile wire at the cut surface, and trim the sensing fiber section with fiber optic shears to ensure that the new sensing fiber can be used normally.

[0028] Step 5: System Recovery

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

[0030] As a preferred method, during replacement, a section of positioning fiber is first spliced ​​to the output end of the old sensing fiber. The distance between the first sensing grating point on the old sensing fiber and a known reference point is then accurately measured using demodulation equipment, thereby marking the accurate position of the first sensing grating point. After replacing the new fiber optic sensor, the position of its first sensing grating point is marked using the same method. Subsequently, the positions of the first sensing grating points of the new and old fibers are made to coincide through traction adjustment, thus achieving in-situ replacement of the sensing fiber.

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

[0032] 1. By setting up entry and exit guides on the main cable, the internal sensing optical fiber of the main cable can be led out, realizing the replacement of the internal sensing optical fiber of the main cable, solving the problem that the sensing optical fiber cannot be replaced, and realizing the monitoring of the internal temperature and humidity of the main cable throughout the entire life cycle of the suspension bridge.

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

[0034] 3. The exposed parts of the main cable steel wires are sealed with a sealing box and a sealing limit sleeve to prevent moisture from corroding the exposed parallel steel wires.

[0035] 4. By bonding tensile wire and sensing fiber, the tensile strength of the sensing fiber is improved, and spiral armor is used for protection, which greatly avoids damage during transportation, installation, and operation.

[0036] 5. Solar batteries and IoT modules are used to transmit the working status of the sensing fiber in real time, ensuring that the sensing fiber can be replaced in a timely manner if it is damaged. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the built-in sensing optical fiber lead-out device in the 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 schematic diagram of the structure of the main cable assembly entry and exit guide in an embodiment of the present invention;

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

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

[0043] Figure 7 This is a cross-sectional view of the sealed box during the state change in an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of the structure of the entry / exit guide in an embodiment of the present invention;

[0045] Figure 9 This is a cross-sectional view of the entry / exit guide in an embodiment of the present invention;

[0046] Figure 10 This is a cross-sectional view of the entry / exit guide in an embodiment of the present invention;

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

[0048] Figure 12 This is a schematic diagram of the sealing and limiting sleeve structure in an embodiment of the present invention;

[0049] Figure 13 This is a schematic diagram of the sensing optical fiber and 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] Explanation of key figure labels:

[0052] 1-Main cable, 11-Sensing fiber optic cable, 114-Spiral armor tube, 111-Temperature grating, 112-Humidity grating, 113-Tension wire, 115-Bonding part, 11a-Old sensing fiber optic cable, 11b-New sensing fiber optic cable, 12-Parallel steel wire, 13-Clearing gap, 2-Inlet / outlet guide, 21-Inlet / outlet guide tube, 22-Reinforcing 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-Pull-and-replace assembly, 4a-First pull-and-replace assembly, 4b-Second pull-and-replace assembly, 41-Winder, 42-Servo motor, 5-Modulator, 6-Internet of Things module, 7-Solar battery, 8-Cable clamp, 9-Curing resin connector. Detailed Implementation

[0053] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0054] Figure 1 This invention relates to an intelligent main cable with built-in sensing optical fibers, applied to a long-span suspension bridge. The main cable 1 has a diameter of 1000mm and a total length of 2500m. A sensing optical fiber 11, with a length of 160m, is installed at the bottom of the suspension section of the main cable 1. Specifically, as shown... Figure 2 As shown, sensing optical fibers 11 are respectively set at the center, edge and half radius of the main cable 1 to perform multi-directional temperature and humidity detection.

[0055] like Figures 1-4 As shown, this is an embodiment of the present invention of an intelligent main cable built-in sensing fiber optic cable lead-out device, installed on the main cable 1. The intelligent main cable built-in sensing fiber optic cable lead-out device is installed between two adjacent cable clamps 8, with a spacing of 16m between the cable clamps 8, and is used for replacing the sensing fiber 11 in the main cable 1. The lead-out device includes an inlet / outlet guide 2 and a sealing box 3. Each sensing fiber 11 is provided with an inlet / outlet guide 2 at both ends for leading the sensing fiber 11 out from inside the main cable 1. Parallel steel wires 12 in the main cable 1 form a clearance gap along the surface. The parallel steel wires 12 are exposed within a clearance gap 13 with a length of 300mm, and a sealing box 3 is provided on the outside.

[0056] In this embodiment, sensing optical fibers 11 are also installed between the anchorages on both banks 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 the sensing optical fiber 11 is connected to an inlet / outlet guide 2 at both ends, ensuring they do not interfere with each other and independently monitor temperature and humidity. When one segment of the sensing optical fiber 11 is damaged, only the damaged segment needs to be replaced. By segmenting the sensing optical fibers 11 and allowing for adjustable lengths, the required continuous length is eliminated, reducing the length of each segment. The fibers can be replaced segment by segment, reducing the cost of replacing the sensing optical fibers.

[0057] like Figures 5-7 The image shows the sealing box 3 in this embodiment of the invention. The sealing box 3 is made of 316L austenitic stainless steel, with dimensions of 1200×1200mm (length × width along the main cable section) and 500mm (axial length along the main cable). The sealing box 3 undergoes anti-corrosion treatment, with electrolytic polishing of both inner and outer surfaces, and a passivation film thickness ≥15nm. 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 sealing box 3, made of 10mm thick polycarbonate optical-grade sheet with a light transmittance >92% and a UV coating, and sealed with a butyl rubber gasket. A through hole 31 is provided on the other side of the sealing box 3, and a sealing limiting sleeve 32 is provided inside the through hole 31.

[0058] like Figure 6 and Figure 7 The diagrams shown illustrate the structure of the sealed box 3 in its service and replacement states, respectively, in an embodiment of the present invention. In the service state, the sensing fiber 11 is connected to the modulator 5, which in turn is connected to the IoT module 6. The modulator 5 uploads the information monitored by the sensing fiber 11 and its operating status to the IoT module 6. The solar battery 7 powers the modulator 5 and the IoT module 6, ensuring uninterrupted operation and allowing maintenance personnel to replace the sensing fiber 11 promptly if it is damaged. In the replacement state, the modulator 5 and the IoT module 6 are disconnected from the sensing fiber 11, and maintenance personnel use the pull-and-replace assembly 4 to replace the sensing fiber 11.

[0059] Specifically, the pull-and-replacement assembly 4 includes a winch 41 and a servo motor 42. During replacement, both ends of the sensing fiber 11 are equipped with the pull-and-replacement assembly 4. One winch 41 has the old sensing fiber 11a wound around it, while the other winch 41 has the new sensing fiber 11b wound around it. The old sensing fiber 11a and the new sensing fiber 11b are bonded together. By controlling the servo motors 42 at both ends to operate synchronously, the two winches 41 are driven to rotate. During rotation, the winches 41 pull on one end of the old sensing fiber 11a, while the other winch 41, controlled by the servo motor 42, synchronously releases the new sensing fiber 11b. During the winding process, the new sensing fiber 11b is pulled back into the main cable 1 until it completely replaces the old sensing fiber 11a. The servo motor 42 is equipped with a torque sensor. By detecting the output torque of the servo motor 42, the tension force on the sensing fiber 11 is controlled, thereby preventing the sensing fiber 11 from being pulled apart.

[0060] like Figures 8-10 The diagram shown is a schematic of the access guide 2 in an embodiment of the present invention. The main body of the access guide 2 is the access guide tube 21. The inner layer of the access 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 access guide tube 21 is electrolytically polished, and the outer layer is micro-arc oxidized. The access guide 2 has 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 count 120) ultrasonically welded to the inner wall of the guide tube and mirror polished with electrolyte. The access guide 2 has a wire hole 23 inside, the diameter of which is 2.4mm, and the two ends are chamfered at C0.2.

[0061] like Figure 11 and Figure 12 The diagram shows a schematic of the sealing and limiting sleeve 32 in an embodiment of the present invention. The sealing and limiting sleeve 32 is located at the opening of the sealing box 3, and has an internal air storage groove 322. A compression piston ring 323 is threaded into the air storage groove 322. Several connecting air pipes 324 connect the air storage groove 322 and the sealing gasket 321. In service, rotating the compression piston ring 323 compresses the air in the air storage groove 322 along the connecting air pipes 324 into the sealing gasket 321, causing it to expand and thus sealing and limiting the sensing fiber optic cable 11, preventing moisture from entering the sealing box 3. During replacement, rotating the compression piston ring 323 in the opposite direction causes the air in the sealing gasket 321 to flow back into the air storage groove 322 along the connecting air pipes 324, allowing the sensing fiber optic cable 11 to be replaced.

[0062] like Figure 13 and Figure 14The diagram shows a sensing optical fiber, tensile wires, and a spiral armor tube in an embodiment of the present invention. The sensing optical fiber 11 has a diameter of Φ0.8mm and is equipped with a temperature grating 111 and a humidity grating 112. Multiple tensile wires 113 with a diameter of Φ0.5mm are located on the outer side of the sensing optical fiber 11 and the multiple tensile wires 113. A spiral armor tube 114 is provided outside the sensing optical fiber 11 and the multiple tensile wires 113. The outer diameter of the spiral armor tube 114 is Φ5.8mm, and the inner diameter is Φ4.8mm. The spiral armor tube 114 provides sufficient channel capacity for replacing the sensing optical fiber 11.

[0063] Specifically, the tensile wire 113 is made of aramid fiber, which provides extremely high tensile strength and also acts as a buffer material to protect the sensing fiber 11. During replacement, it serves as the main tensile reinforcement of the fiber bundle, bearing most of the tensile force and protecting the temperature grating 111 and humidity grating 112. The remaining specific parameters of the sensing fiber 11 and the tensile wire 113 are shown in the table below:

[0064]

[0065]

[0066] In this embodiment of the invention, the portion of the sensing fiber 11 without the temperature grating 111 and humidity grating 112 is effectively connected to the corresponding portion of the tensile wires 113 via resin to form an adhesive portion 115. Four tensile wires 113 are bonded to the outside of the sensing fiber 11. The sensing fiber 11 and the four tensile wires 113 share the force, preventing the sensing fiber 11 from breaking under tension during replacement, and also preventing friction damage between the sensing fiber 11 and the spiral armor tube 114 during replacement. In another embodiment of the invention, the outside of the sensing fiber 11 is formed by diagonally weaving multiple tensile wires 113 to form a porous mesh protective sleeve, thereby improving the tensile strength of the sensing fiber 11 and preventing damage to the sensing fiber 11 during replacement.

[0067] The method for replacing the sensing fiber using the intelligent main cable built-in sensing fiber lead-out device of the present invention includes the following steps:

[0068] Step 1, Disconnect:

[0069] Before the replacement of the sensing fiber 11, it was the old sensing fiber 11a. After the replacement of the sensing fiber 11, it was the new sensing fiber 11b. Rotate the sealing limit sleeve 32 on the sealing box 3, open the through hole 31, and disconnect the old sensing fiber 11a from the modulator 5 outside the sealing box 3.

[0070] Step 2, Connecting the old and new fiber optic cables:

[0071] The traction replacement assembly 4 is divided into a first traction replacement assembly 4a and a second traction replacement assembly 4b. The old sensing fiber 11a and one end of the tensile wire 113 are wound around the winch 41 of the first traction replacement assembly 4a and anti-slip treatment is applied. The new sensing fiber 11b and the tensile wire 113 are wound around the winch 41 of the second traction replacement assembly 4b. Sufficient overlap length is reserved between the old and new fibers. UV curing resin is applied to the overlap and UV lamp is used to form a cured resin joint 9.

[0072] Step 3, Synchronous Traction:

[0073] The servo motors 42 at both ends are started, and the winding and unwinding are controlled synchronously by adjusting the speed of the servo motors 42, allowing the new sensing fiber 11b to enter the main cable 1 along the inlet / outlet guide 2. During the pulling process, the speed of the servo motor 42 of the second pulling replacement component 4b is adjusted to be slightly greater than the speed of the servo motor 42 of the first pulling replacement component 4a, ensuring that the sensing fiber is always in a slack state during the pulling process. At the same time, a torque sensor is used to monitor the output torque of the servo motors. When the output torque of the servo motors exceeds the preset threshold, the rotation of the servo motors 42 at both ends is stopped, and manual inspection and troubleshooting are performed to avoid damage to the sensing fiber.

[0074] Step 4: Cut the sensing fiber:

[0075] When the cured resin connector 9 reaches the position of the first pull replacement component 4a, the pull is stopped. Sufficient length of sensing fiber 11 and tensile wire 113 is reserved outside the sealed box 3. The new sensing fiber 11b and tensile wire 113 are cut from the cured resin connector 9 with pliers. Then, the sensing fiber 11 and tensile wire 113 at the cut are peeled off, and the cross-section of the sensing fiber is trimmed with fiber optic shears to ensure that the new sensing fiber 11b can be used normally.

[0076] Step 5: System Recovery

[0077] Connect the new sensing fiber 11b to the modulator 5, test and calibrate the new sensing fiber 11b, rotate the sealing limit sleeve on the sealing box in the opposite direction to close the through hole, and the replacement is complete.

[0078] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A smart main cable with built-in sensing optical fiber lead-out device, characterized in that, Includes a main cable (1), which is equipped with a sensing optical fiber (11) and parallel steel wires (12). The sensing fiber (11) is arranged along the axial direction of the main cable (1). The main cable (1) is provided with cable clips (8). The two ends of the sensing fiber (11) are respectively set between two adjacent cable clips (8) on the main cable (1). The sensing fiber (11) is connected to a set of lead-out devices, which include an inlet / outlet guide (2) and a sealing box (3). The inlet / outlet guide (2) leads the sensing optical fiber (11) out from inside the main cable (1); the parallel steel wires (12) in the main cable (1) form a clearance gap (13) along the surface of the inlet / outlet guide (2); the parallel steel wires (12) inside the main cable (1) in the 100~400mm length range of the clearance gap (13) are exposed, and a sealed box (3) is provided on the outside. The inlet / outlet guide (2) of the lead-out device includes an inlet / outlet guide tube (21), a reinforcing mesh tube (22), and a wire hole (23). The inlet / outlet guide tube (21) has a double-layer structure, with the inner layer made of high-strength material. The inner diameter of the wire hole (23) is larger than the outer diameter of the sensing optical fiber (11). A reinforcing mesh tube (22) is fixedly installed inside the wire hole (23), and the inner wall of the reinforcing mesh tube (22) is made of polished material. The inlet / outlet guide (2) is adapted to the internal configuration of the main cable (1), and its cross-sectional shape is either spindle-shaped or elliptical. The sealing box (3) of the lead-out device is set at the exposed position of the parallel steel wire (12) at the clearance gap (13), and is fixedly connected to the surface of the main cable (1). The contact surface with the main cable (1) is provided with a rubber sealing layer (33). The sealed box (3) has an observation window (34) on one side wall and a through hole (31) on the other side wall. A sealing limiting sleeve (32) is provided in the through hole (31). The sensing fiber (11) extends from the inside of the main cable (1) into the sealed box (3) through the inlet and outlet guide (2) and passes through the sealing limiting sleeve (32) to the outside of the sealed box (3). In service, the sensing fiber (11) is connected to the modulator (5), and the modulator (5) is connected to the Internet of Things module (6). The modulator (5) and the Internet of Things module (6) are powered by a solar battery (7). In replacement, the sensing fiber (11) is connected to the traction replacement assembly (4). The traction replacement assembly (4) includes a winch (41) and a servo motor (42). A sealing gasket (321) is fixedly connected to the inner wall of the sealing limiting sleeve (32). An air storage groove (322) is opened inside the sealing limiting sleeve (32). A compression piston ring (323) is threadedly connected inside the air storage groove. Several connecting air pipes (324) are connected between the air storage groove and the sealing gasket.

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

3. The intelligent main cable built-in sensing fiber optic lead-out device according to claim 2, 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 pasted on the outside of the humidity grating (112). A rigid protective sleeve is provided outside the temperature grating (111), and a rigid protective sleeve with ventilation holes is provided outside the humidity grating (112). Multiple tensile wires (113) are provided on the outside of the sensing optical fiber (11). Spiral armor tubes (114) are provided outside the sensing optical fiber (11) and the tensile wires (113). The parts of the sensing optical fiber (11) without temperature gratings (111) and humidity gratings (112) are connected to the tensile wires (113) by resin to form an adhesive part (115).

4. A method for replacing the sensing fiber using the intelligent main cable built-in sensing fiber lead-out device as described in claim 1, 2, or 3, characterized in that, Includes the following steps: Step 1, Disconnect: Before the replacement of the sensing fiber (11), it was the old sensing fiber (11a). After the replacement of the sensing fiber (11), it was the new sensing fiber (11b). Rotate the sealing limit sleeve (32) on the sealing box (3), open the through hole (31), and disconnect the old sensing fiber (11a) from the modulator (5) outside the sealing box (3). Step 2, Connecting the old and new fiber optic cables: The pull replacement assembly (4) is divided into a first pull replacement assembly (4a) and a second pull replacement assembly (4b). The old sensing fiber (11a) and one end of the tensile wire (113) are wound around the winch (41) of the first pull replacement assembly (4a) and anti-slip treatment is applied. The new sensing fiber (11b) and tensile wire (113) are wound around the winch (41) of the second pull replacement assembly (4b). Sufficient overlap length is reserved between the old and new fibers. UV curing resin is applied to the overlap and UV lamp is used to form a cured resin joint (9). Step 3, Synchronous Traction: Start the servo motors (42) at both ends, and control the winding and unwinding synchronously by adjusting the speed of the servo motors (42) to allow the new sensing fiber (11b) to enter the main cable (1) along the inlet and outlet guide (2); during the pulling process, adjust the speed of the servo motor (42) of the second pulling replacement component (4b) to make it slightly greater than the speed of the servo motor (42) of the first pulling replacement component (4a) to ensure that the sensing fiber is always in a relaxed state during the pulling process; at the same time, use a torque sensor to monitor the output torque of the servo motor. When the output torque of the servo motor exceeds the preset threshold, stop the rotation of the servo motors (42) at both ends, and perform manual inspection and troubleshooting to avoid damage to the sensing fiber; Step 4: Cut the sensing fiber: When the cured resin connector (9) reaches the position of the first pull replacement component (4a), the pull is stopped. Sufficient length of sensing fiber (11) and tensile wire (113) is reserved outside the sealed box (3). The new sensing fiber (11b) and tensile wire (113) are cut from the cured resin connector (9) with pliers. Then the sensing fiber (11) and tensile wire (113) at the cut are stripped and the cross-section of the sensing fiber is trimmed with fiber optic shears to ensure that the new sensing fiber (11b) can be used normally. Step 5: System Recovery Connect the new sensing fiber (11b) to the modulator (5), test and calibrate the new sensing fiber (11b), rotate the sealing limit sleeve on the sealing box in the opposite direction to close the through hole, and the replacement is complete.

5. The method for replacing the sensing fiber according to claim 4, characterized in that, During replacement, firstly, a positioning fiber is spliced ​​to the output end of the old sensing fiber (11a). The distance between the first sensing grating point on the old sensing fiber (11a) and the known reference point is accurately measured using demodulation equipment, thereby marking the accurate position of the first sensing grating point. After replacing the new sensing fiber (11b), the position of its first sensing grating point is marked in the same way. Then, by traction adjustment, the positions of the first sensing grating points of the new and old fibers are made to coincide, thus realizing the in-situ replacement of the sensing fiber.

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