Method and system for monitoring broken wires of parallel steel wire inhaul cable based on weak grating optical fiber

Abstract

The invention relates to the technical field of inhaul cable monitoring, in particular to a parallel steel wire inhaul cable broken wire monitoring method and monitoring system based on weak grating optical fibers. The method includes the steps that when an inhaul cable is manufactured, weak grating sensing optical fibers are installed in the inhaul cable, the weak grating sensing optical fibers are arranged along the whole length of the inhaul cable, and a plurality of strain grating measuring points are evenly arranged on the weak grating sensing optical fibers at intervals in the length direction; in the service stage of the inhaul cable, installing an optical fiber demodulator to be in signal connection with the weak grating sensing optical fiber in the inhaul cable; weak grating sensing optical fiber signal wavelength is collected in real time based on an optical fiber demodulator, and the broken wire condition in the inhaul cable is determined according to the relation between the weak grating sensing optical fiber signal wavelength and the number of broken wires in the inhaul cable. The method for monitoring the broken wire of the parallel steel wire inhaul cable based on the weak grating optical fiber is very simple, the breakage condition of the steel wire in the inhaul cable can be accurately monitored, interference of the external environment is avoided, the overall monitoring result is accurate, and the monitoring method is simple.

Description

Technical Field

[0001] The present application relates to the technical field of cable monitoring, and specifically to a method and system for monitoring broken wires of parallel steel cables based on weak grating optical fibers. Background Art

[0002] The parallel wire cable structure consists of anchors, hundreds of steel wires and HDPE sheaths. It is widely used in cable-stayed bridge cables, arch bridge hangers (ties), suspension bridge hangers and other large structures.

[0003] Since parallel steel wire cables are generally arranged outside the structure, their HDPE sheaths are prone to cracking due to the combined effects of various external factors. After the sheath is opened, rainwater, moisture, harmful gases, and corrosive substances will invade the interior of the cables, causing the steel wires to rust or even break, thereby endangering the safety of the cables and bridge structures.

[0004] At present, the commonly used methods for detecting broken wires in cables mainly include window detection method, magnetic flux detection method, acoustic emission detection method, ultrasonic monitoring method, etc. For example, public information mentions a new type of prestressed steel cylinder concrete pipe with pre-embedded acoustic emission sensors and distributed optical fibers, as well as a manufacturing and broken wire monitoring method. This method conducts signal testing before the prestressed steel cylinder concrete pipe leaves the factory, simulates various environmental noises and broken wire phenomena that occur during on-site monitoring, uses distributed optical fiber and acoustic emission equipment to monitor it, establishes a signal sample database, and uses machine learning algorithms to train a broken wire signal recognition model based on the database, receives and synchronously records the signals of the optical fiber demodulator and acoustic emission collector in real time, and inputs the distributed optical fiber signals obtained by monitoring into the broken wire signal recognition model for classification, thereby determining whether a broken wire occurs, and also being able to locate the position of the broken wire. This solution is relatively simple, mainly because the initial model construction is relatively complex and the subsequent monitoring is relatively simple. However, this solution also has many problems. The most important one is that it is greatly restricted by the environment. The distributed optical fiber collects not only the sound signal of the acoustic emission equipment, but also the interference of external environmental noise. Although the problem of environmental noise is taken into account when building the model, in actual applications, it is impossible to eliminate the interference of all environmental noise. Therefore, the solution actually obtains a rough signal, and there is a large error in the monitoring of broken wires.

[0005] Other wire rope broken wire monitoring methods such as magnetic flux detection method and ultrasonic monitoring method also have corresponding problems, that is, the interference from the external environment is large and it is not suitable for large-scale promotion and application. The window detection method is a destructive detection method, which is destructive to the original cable structure and is even more unsuitable for promotion and application. Therefore, there is an urgent need for a non-destructive wire broken wire monitoring method that is not affected by the external environment. Summary of the invention

[0006] The purpose of this application is to solve the deficiencies of the above-mentioned background technology and to provide a parallel steel wire rope broken wire monitoring method and monitoring system based on weak grating optical fiber.

[0007] The technical solution of the present application is: a method for monitoring the broken wires of parallel steel cables based on weak grating optical fibers, comprising:

[0008] When manufacturing the cable, a weak grating sensing optical fiber is installed in the cable, the weak grating sensing optical fiber is arranged along the entire length of the cable, and a plurality of strain grating measuring points are evenly spaced along the length direction on the weak grating sensing optical fiber;

[0009] When the cable is in service, a fiber demodulator is installed to connect with the weak grating sensing fiber signal in the cable;

[0010] The optical fiber demodulator is used to collect the wavelength of the weak grating sensing optical fiber signal in real time, and the broken wire situation in the cable is determined according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable.

[0011] According to a method for monitoring broken wires in parallel steel cables based on weak grating optical fibers provided by the present application, the method for determining the broken wire situation in the cable based on the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable comprises: constructing the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable according to the following formula:

[0012]

[0013] Where: Δλ i ——Wavelength of weak grating sensing fiber signal;

[0014] F——cable force;

[0015] K i ——Strain sensitivity of weak grating sensing fiber;

[0016] A——cross-sectional area of ​​the steel wire in the cable;

[0017] n——Total number of steel wires in the cable;

[0018] d——Number of broken wires in the cable;

[0019] E is the elastic modulus of the steel wire in the cable.

[0020] According to a method for monitoring broken wires in a parallel steel wire rope based on weak grating optical fiber provided in the present application, the method for installing a weak grating sensing optical fiber in the rope comprises: when manufacturing the rope, replacing a steel wire in the rope with a structure encapsulated with a weak grating sensing optical fiber, so that the weak grating sensing optical fiber is arranged throughout the length of the rope, and signal leads connected to the weak grating sensing optical fiber signal are reserved at both ends of the rope.

[0021] According to a method for monitoring broken wires in a parallel steel cable based on weak grating optical fiber provided in the present application, the method of replacing a steel wire in the cable with a structure encapsulated with a weak grating sensing optical fiber includes: replacing a steel wire at the center of the cable with a structure encapsulated with a weak grating sensing optical fiber.

[0022] According to a method for monitoring broken wires of parallel steel cables based on weak grating optical fibers provided in the present application, the method for installing an optical fiber demodulator includes: after the bridge is formed, connecting a reserved signal lead passing through the tail end of the cable anchor head to the optical fiber demodulator.

[0023] According to a method for monitoring broken wires of parallel steel cables based on weak grating optical fiber provided in the present application, the spacing between adjacent strain grating measuring points on the weak grating sensing optical fiber is 0.2m to 1m.

[0024] The present application also relates to a parallel steel cable broken wire monitoring system based on weak grating optical fiber, the monitoring system is operated according to the above-mentioned parallel steel cable broken wire monitoring method based on weak grating optical fiber, including:

[0025] An optical fiber module, wherein the optical fiber module comprises a weak grating sensing optical fiber installed in the cable; the weak grating sensing optical fiber is arranged along the entire length of the cable and a plurality of strain grating measuring points are evenly spaced along the length direction of the weak grating sensing optical fiber;

[0026] A receiving module, wherein the signal receiving module includes an optical fiber demodulator; the optical fiber demodulator is connected to the weak grating sensing optical fiber signal in the cable;

[0027] A calculation module is provided, wherein the calculation module determines the broken wire situation in the cable according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable.

[0028] According to the present application, a parallel steel wire cable broken wire monitoring system based on weak grating optical fiber is provided, wherein the calculation module constructs the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable according to the following formula, and calculates the number of broken wires in the cable according to the formula;

[0029]

[0030] Where: Δλ i ——Wavelength of weak grating sensing fiber signal;

[0031] F——cable force;

[0032] K i ——Strain sensitivity of weak grating sensing fiber;

[0033] A——cross-sectional area of ​​the steel wire in the cable;

[0034] n——Total number of steel wires in the cable;

[0035] d——Number of broken wires in the cable;

[0036] E is the elastic modulus of the steel wire in the cable.

[0037] According to the present application, a parallel steel cable breakage monitoring system based on weak grating optical fiber is provided, and the optical fiber module includes a weak grating sensing optical fiber located at the center of the cable.

[0038] According to the present application, a parallel steel cable breakage monitoring system based on weak grating optical fiber is provided. After the bridge is formed, the optical fiber demodulator of the receiving module is connected to the weak grating sensing optical fiber through a reserved signal lead passing through the tail end of the cable anchor head.

[0039] The advantages of the present application are as follows: 1. The present application arranges weak grating sensing optical fibers in parallel steel wire cables, and uses weak grating sensing optical fibers to monitor the cables in real time. The weak grating sensing optical fibers collect internal signals, and the number of broken wires in the cables is obtained based on the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cables. This method is not affected by the external environment, and the sound, light and electricity of the external environment will not affect the monitoring results. Therefore, the number of broken wires in the cables can be accurately obtained, the overall monitoring results are accurate, the monitoring method is simple, and it is suitable for large-scale promotion and application;

[0040] 2. The relationship between the wavelength of the weak grating sensing optical fiber signal constructed in this application and the number of broken wires in the cable is very simple and clear. By constructing the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable, the number of broken wires in the cable can be well monitored, the calculation is very convenient, and the monitoring result is extremely accurate;

[0041] 3. The method of installing the weak grating sensing optical fiber inside the cable in the present application is very simple. It only needs to replace one of the parallel steel wires in the cable with the weak grating sensing optical fiber. The overall installation arrangement is very simple. The weak grating sensing optical fiber inside the cable collects stable signals and is not affected by the external environment.

[0042] 4. The weak grating sensing optical fiber inside the cable of the present application is located at the center of the cable, that is, the weak grating sensing optical fiber is located at the center of the cable. The weak grating sensing optical fiber inside the cable can collect more comprehensive signals of the broken wire situation of the steel wire. The collected signals can accurately and truly reflect the broken wire situation inside the cable, which is convenient for accurately obtaining the overall situation of the cable;

[0043] 5. The method of connecting the optical fiber demodulator in this application is very simple. It only needs to connect the signal lead to the optical fiber demodulator after the bridge is formed. The signal collected by the weak grating sensor optical fiber can be stably transmitted to the optical fiber demodulator, which is convenient for subsequent accurate analysis of the steel wire breakage situation.

[0044] The present application is a very simple method for monitoring broken wires in parallel steel cables based on weak grating sensing optical fiber, which can accurately monitor the breakage of the steel wires inside the cables without being disturbed by the external environment. The overall monitoring results are accurate, the monitoring method is simple, and it is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 : Schematic diagram of the cable cross section of the present application;

[0046] Among them: 1—weak grating sensing optical fiber; 2—steel wire; 3—HDPE sheath. DETAILED DESCRIPTION

[0047] The embodiments of the present application are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0048] In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0050] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0051] The present application relates to a parallel steel wire cable broken wire monitoring method based on weak grating optical fiber. The monitoring method of the present application is mainly used for parallel steel wire cables. A weak grating sensing optical fiber arranged throughout the length of the cable is installed, and the signal inside the cable is collected using the weak grating sensing optical fiber. The steel wire breakage inside the cable is then determined based on the relationship between the constructed weak grating sensing optical fiber signal and the number of broken steel wires. Since the weak grating sensing optical fiber of the present application is directly arranged inside the cable, the collected signal is the wavelength signal of the weak grating sensing optical fiber, which is not affected by external environmental factors, and the monitoring result is more accurate and intuitive. At the same time, the weak grating sensing optical fiber arranged inside the cable can be consistent with the life of the cable, which can be up to more than 20 years. The cable broken wire monitoring method of the present application has the advantages of simplicity, accuracy, intuitiveness and long life.

[0052] Specifically, the parallel steel wire cable structure of the present application is as follows: Figure 1 As shown, a plurality of steel wires 2 are arranged inside the cable, and the axes of all the steel wires 2 are parallel to each other. After all the steel wires 2 form a steel wire bundle, an HDPE sheath 3 is encapsulated outside, and a weak grating sensing optical fiber 1 is arranged inside the steel wire bundle to collect the broken wire situation of the steel wire 2 in real time. Specifically, a parallel steel wire cable broken wire monitoring method based on weak grating optical fiber of the present application includes the following steps:

[0053] S1. When manufacturing the cable, a weak grating sensing optical fiber is installed in the cable. The weak grating sensing optical fiber is arranged along the entire length of the cable and a plurality of strain grating measuring points are evenly spaced along the length direction on the weak grating sensing optical fiber.

[0054] The weak grating sensing optical fiber is arranged in the steel wire bundle. Therefore, in actual use, the weak grating sensing optical fiber is not only protected by the steel wire bundle, but also protected by the HDPE sheath. Therefore, the weak grating sensing optical fiber is not easily damaged, which can ensure that the life of the weak grating sensing optical fiber is consistent with that of the entire cable.

[0055] Multiple strain grating measuring points are evenly arranged on the weak grating sensing optical fiber. The location of wire breakage can be determined by collecting the signals and arrangement positions of the strain grating measuring points, and the wire breakage situation inside the cable can be accurately obtained.

[0056] S2. When the cable is in service, install an optical fiber demodulator to connect with the weak grating sensing optical fiber signal in the cable;

[0057] The signal of the weak grating sensing optical fiber is collected in real time by arranging an optical fiber demodulator, which is a high-frequency demodulator capable of processing the signal of the weak grating sensing optical fiber;

[0058] S3, based on the optical fiber demodulator, the wavelength of the weak grating sensing optical fiber signal is collected in real time, and the broken wire situation in the cable is determined according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable;

[0059] Experimental analysis shows that the signal wavelength of the weak grating sensing optical fiber installed inside the cable is correlated with the number of broken steel wires. By obtaining this correlation, the number of broken steel wires can be converted through the signal wavelength of the weak grating sensing optical fiber during the actual monitoring process, and the broken steel wire situation inside the cable can be obtained in real time.

[0060] In some embodiments of the present application, the present embodiment optimizes the above step S1, and the arrangement of the weak grating sensing optical fiber inside the cable is to install the weak grating sensing optical fiber inside the steel wire bundle. When the cable is manufactured, a steel wire inside the cable is replaced with a structure encapsulating the weak grating sensing optical fiber, specifically, a steel wire at the center of the cable is replaced with a structure encapsulating the weak grating sensing optical fiber. The weak grating sensing optical fiber is arranged throughout the length of the cable, and signal leads connected to the weak grating sensing optical fiber signal are reserved at both ends of the cable.

[0061] The weak grating sensing optical fiber is arranged throughout the length of the cable, so the breakage of the steel wire at any length position in the cable can be monitored. At the same time, multiple strain grating measuring points are evenly arranged on the weak grating sensing optical fiber, which can quickly and densely obtain the broken wire signal at any position of the entire length of the cable.

[0062] This embodiment sets the arrangement of the strain gratings, and the spacing between adjacent strain grating measuring points is 0.2m to 1m, so that the broken wire signals at any position along the entire length of the cable can be accurately collected in real time and densely. The location where the broken wire occurs can be obtained based on the broken wire signals collected by the strain grating measuring points.

[0063] In other embodiments of the present application, the present embodiment optimizes the above-mentioned step S2. Specifically, after the bridge is built, the reserved signal lead passing through the tail end of the cable anchor head is connected to the optical fiber demodulator. The cable of the present embodiment is a cable structure for a bridge. After the bridge is built, the cable is installed. The optical fiber demodulator is arranged at the anchor head position at the end of the cable and connected to the above-mentioned cable signal lead. The optical fiber demodulator can collect the signal of the grating sensing optical fiber inside the cable through the signal lead.

[0064] In a further embodiment of the present application, the present embodiment optimizes the above-mentioned step S3, and the present embodiment optimizes the relationship between the above-mentioned weak grating sensing fiber signal wavelength and the number of broken wires in the cable, and constructs the relationship between the weak grating sensing fiber signal wavelength and the number of broken wires in the cable according to the following formula:

[0065]

[0066] Where: Δλ i ——The wavelength of the weak grating sensing fiber signal is collected by the fiber demodulator;

[0067] F——Force on the cable, which can be measured by pressure ring, accelerometer, etc.

[0068] K i ——Strain sensitivity of weak grating sensing fiber ， Obtained during the factory inspection process when the cable is manufactured;

[0069] A——Cross-sectional area of ​​the steel wire in the cable, measured when the cable is manufactured;

[0070] n——Total number of steel wires in the cable, measured when the cable is manufactured;

[0071] d——Number of broken wires in the cable;

[0072] E is the elastic modulus of the steel wire in the cable, which can be obtained by looking up the table according to the material of the steel wire used in the cable.

[0073] That is, there is a functional relationship between the wavelength of the weak grating sensing fiber signal of the present embodiment and the number of broken wires in the cable. After the wavelength of the weak grating sensing fiber signal is collected by the optical fiber demodulator, the number of broken wires in the cable can be converted by the above formula, thereby accurately obtaining the broken wire situation inside the cable.

[0074] An early warning can be issued based on the broken wire situation inside the cable, that is, a wire breakage early warning value is set. When the number of broken wires inside the cable exceeds the early warning value, an alarm is issued to avoid safety accidents.

[0075] In actual use, when manufacturing the cable, a steel wire at the center of the cable is replaced with a weak grating sensing optical fiber. The weak grating sensing optical fiber is arranged along the entire length of the cable, and multiple strain grating measuring points are evenly spaced along the length direction on the weak grating sensing optical fiber, and signal leads connected to the weak grating sensing optical fiber signal are reserved at both ends of the cable; after the bridge is formed, the reserved signal lead passing through the tail end of the cable anchor head is connected to the optical fiber demodulator; the wavelength of the weak grating sensing optical fiber signal is collected by the optical fiber demodulator, and the number of broken wires in the cable is obtained according to the following formula:

[0076]

[0077] Where: Δλ i ——Wavelength of weak grating sensing fiber signal;

[0078] F——cable force;

[0079] K i ——Strain sensitivity of weak grating sensing fiber;

[0080] A——cross-sectional area of ​​the steel wire in the cable;

[0081] n——Total number of steel wires in the cable;

[0082] d——Number of broken wires in the cable;

[0083] E——elastic modulus of the steel wire in the cable;

[0084] The number of broken wires in the cable is obtained, the number of broken wires in the cable is compared with the warning value, and an alarm is issued when the number of broken wires exceeds the warning value.

[0085] In addition, the present application also relates to a parallel steel wire rope broken wire monitoring system based on weak grating optical fiber. The monitoring system operates according to the above-mentioned parallel steel wire rope broken wire monitoring method based on weak grating optical fiber, including an optical fiber module, a receiving module and a computing module. The optical fiber module includes a weak grating sensing optical fiber installed in the rope; the weak grating sensing optical fiber is arranged along the entire length of the rope and a plurality of strain grating measuring points are evenly spaced along the length direction on the weak grating sensing optical fiber; the signal receiving module includes an optical fiber demodulator; the optical fiber demodulator is connected to the weak grating sensing optical fiber signal in the rope; the computing module determines the broken wire situation in the rope according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the rope.

[0086] The calculation module constructs the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable according to the following formula, and calculates the number of broken wires in the cable according to the formula;

[0087]

[0088] Where: Δλ i ——Wavelength of weak grating sensing fiber signal;

[0089] F——cable force;

[0090] K i ——Strain sensitivity of weak grating sensing fiber;

[0091] A——cross-sectional area of ​​the steel wire in the cable;

[0092] n——Total number of steel wires in the cable;

[0093] d——Number of broken wires in the cable;

[0094] E is the elastic modulus of the steel wire in the cable.

[0095] The fiber optic module includes a weak grating sensing fiber located at the center of the cable.

[0096] After the bridge is formed, the optical fiber demodulator of the receiving module is connected to the weak grating sensing optical fiber through a reserved signal lead passing through the tail end of the cable anchor head.

[0097] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.

Claims

1. A method for monitoring broken wires of parallel steel cables based on weak grating optical fiber, characterized in that: include, When manufacturing the cable, a weak grating sensing optical fiber is installed in the cable, the weak grating sensing optical fiber is arranged along the entire length of the cable, and a plurality of strain grating measuring points are evenly spaced along the length direction on the weak grating sensing optical fiber; When the cable is in service, a fiber demodulator is installed to connect with the weak grating sensing fiber signal in the cable; The optical fiber demodulator is used to collect the wavelength of the weak grating sensing optical fiber signal in real time, and the broken wire situation in the cable is determined according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable.

2. A method for monitoring broken wires of parallel steel cables based on weak grating optical fiber as claimed in claim 1, characterized in that: The method for determining the broken wire situation in the cable according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable comprises: constructing the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable according to the following formula: Where: Δλ i ——Wavelength of weak grating sensing fiber signal; F——cable force; K i ——Strain sensitivity of weak grating sensing fiber; A——cross-sectional area of ​​the steel wire in the cable; n——Total number of steel wires in the cable; d——Number of broken wires in the cable; E is the elastic modulus of the steel wire in the cable.

3. A method for monitoring broken wires of parallel steel cables based on weak grating optical fiber as claimed in claim 1, characterized in that: The method for installing a weak grating sensing optical fiber in a cable comprises: when manufacturing the cable, replacing a steel wire in the cable with a structure encapsulating the weak grating sensing optical fiber, so that the weak grating sensing optical fiber is arranged throughout the length of the cable, and signal leads connected to the weak grating sensing optical fiber signal are reserved at both ends of the cable.

4. A method for monitoring broken wires of parallel steel cables based on weak grating optical fiber as claimed in claim 3, characterized in that: The method for replacing a steel wire in a cable with a structure encapsulating a weak grating sensing optical fiber comprises: replacing a steel wire at the center of the cable with a structure encapsulating a weak grating sensing optical fiber.

5. A method for monitoring broken wires of parallel steel cables based on weak grating optical fiber as claimed in claim 1, characterized in that: The method for installing the optical fiber demodulator comprises: after the bridge is built, connecting the reserved signal lead passing through the tail end of the cable anchor head with the optical fiber demodulator.

6. A method for monitoring broken parallel steel cables based on weak grating optical fiber as claimed in claim 1, characterized in that: The distance between adjacent strain grating measuring points on the weak grating sensing optical fiber is 0.2m to 1m.

7. A parallel steel cable broken wire monitoring system based on weak grating optical fiber, characterized by: The monitoring system is operated according to any one of the parallel steel cable broken wire monitoring methods based on weak grating optical fiber as described in claims 1 to 6, include, An optical fiber module, wherein the optical fiber module comprises a weak grating sensing optical fiber installed in the cable; the weak grating sensing optical fiber is arranged along the entire length of the cable and a plurality of strain grating measuring points are evenly spaced along the length direction of the weak grating sensing optical fiber; A receiving module, wherein the signal receiving module includes an optical fiber demodulator; the optical fiber demodulator is connected to the weak grating sensing optical fiber signal in the cable; A calculation module is provided, wherein the calculation module determines the broken wire situation in the cable according to the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable.

8. A parallel steel cable broken wire monitoring system based on weak grating optical fiber as claimed in claim 7, characterized in that: The calculation module constructs the relationship between the wavelength of the weak grating sensing optical fiber signal and the number of broken wires in the cable according to the following formula, and calculates the number of broken wires in the cable according to the formula; Where: Δλ i ——Wavelength of weak grating sensing fiber signal; F——cable force; K i ——Strain sensitivity of weak grating sensing fiber; A——cross-sectional area of ​​the steel wire in the cable; n——Total number of steel wires in the cable; d——Number of broken wires in the cable; E is the elastic modulus of the steel wire in the cable.

9. A parallel steel cable broken wire monitoring system based on weak grating optical fiber as claimed in claim 7, characterized in that: The optical fiber module includes a weak grating sensing optical fiber located at the inner axis of the cable.

10. A parallel steel cable broken wire monitoring system based on weak grating optical fiber as claimed in claim 7, characterized in that: After the bridge is formed, the optical fiber demodulator of the receiving module is connected to the weak grating sensing optical fiber through a reserved signal lead passing through the tail end of the cable anchor head.

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