Pipeline pipe segment dislocation analysis method based on distributed optical fiber sensing

Abstract

The application discloses a pipeline pipe joint dislocation analysis method based on distributed optical fiber sensing and belongs to the technical field of pipeline detection. The method comprises a sensing module, an optical cable calibration module, a signal monitoring module, a pipe joint position mapping module, a dislocation identification module and a visual display module. The sensing module is a double-core sensing optical cable arranged in the pipeline by a special method. The optical cable calibration module calculates the length proportion relationship of two fiber cores. The signal monitoring module is used for collecting the light intensity signal of the optical cable. The pipe joint position mapping module is used for temporarily deploying the mapping between the light intensity curve and the actual position of the pipe joint. The dislocation identification module is used for mining effective characteristic parameters from the light intensity curve and then identifying the pipe joint dislocation position and degree. The visual module is used for directly displaying the pipeline dislocation state identification result to the operator. The application adopts the above method, uses the pre-buried sensing optical cable in the pipeline as a sensor and uses the optical fiber sensing technology to detect the pipeline dislocation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline detection, and in particular to a pipeline segment misalignment analysis method based on distributed optical fiber sensing. BACKGROUND

[0002] Large water transmission pipelines are the core components of urban water supply and irrigation systems, ensuring the effective transportation and distribution of water resources. During long-term use, pipelines may be affected by external forces and internal pressure changes, leading to misalignment and deformation. These phenomena often result from the formation of cavities caused by geological disasters or significant differences in soil conditions along the pipeline layout, causing uneven stress on the pipeline. The burst time of such misaligned pipelines is sudden, which may lead to water supply interruption and cause serious secondary disasters. The water flow generated after the pipeline bursts may erode surrounding roads and buildings, causing collapse, traffic congestion, and even casualties, resulting in significant economic losses and social negative impacts.

[0003] Traditional detection methods mainly include visual inspection, acoustic detection, and manual excavation. Although these methods are effective in certain situations, they often rely on periodic inspections and are difficult to achieve real-time monitoring. Manual excavation methods are destructive and can only sample a small number of pipelines for verification, which is inefficient, costly, and may affect normal water transportation functions. SUMMARY

[0004] The purpose of the present application is to provide a pipeline segment misalignment analysis method based on distributed optical fiber sensing. To address the difficulties in large pipeline misalignment detection and the inconvenience of operation, optical fiber sensing technology is used to detect pipeline misalignment. The pre-buried sensing optical cable within the pipeline is used as a sensor, and the collected signals are demodulated and analyzed using distributed optical fiber sensing technology to achieve high-precision misalignment monitoring and health status evaluation of the pipeline, thereby ensuring the safety of water resource transportation.

[0005] To achieve the above purpose, the present application provides a pipeline segment misalignment analysis method based on distributed optical fiber sensing, comprising the following steps:

[0006] S1: A double-core sensing optical cable is arranged on the inner side of the pipeline as a sensing module. A signal monitoring module, a segment position mapping module, a misalignment identification module, and a visualization module are correspondingly arranged at the starting point of the pipeline, and a Faraday rotator is arranged at the tail end of the pipeline;

[0007] S2: The two optical fibers in the double-core sensing optical cable are connected to the signal monitoring module and the segment position mapping module, respectively. The signal detection module obtains the light intensity curve of the scattered light in the corresponding optical fiber, and the segment position mapping module obtains the intermediate frequency signal of the scattered light in the corresponding optical fiber;

[0008] S3: A Faraday rotator mirror is arranged at the tail end of the two optical fibers; the signal monitoring module and the pipe joint position mapping module detect the optical fibers, and the length ratio P of the two optical fibers is obtained by using the Faraday rotator mirror and the signal monitoring module and the pipe joint position mapping module to detect the length of the optical fibers;

[0009] S4: The operator taps the pipe joints connected by the pipeline in sequence, the pipe joints vibrate, and the pipe joint position mapping module detects the vibration information at the pipe joints by the intermediate frequency signal, which is used to locate the distance of the pipe joints from the starting point;

[0010] S5: The misalignment recognition module includes an effective feature parameter extraction module and a misalignment position and degree recognition module, which combines the intermediate frequency signal, the light intensity curve and the ratio P to form a mapping relationship between the pipe joint position and the light intensity curve, and form a pipeline state curve T s , and further recognize the misalignment state of the pipeline;

[0011] S6: The pipeline state is displayed by the visualization module, including but not limited to the pipe joint misalignment position, the current light intensity curve, and the pipe joint position mapping data of the cable skin length.

[0012] Preferably, in step S1, the following is specifically provided

[0013] The signal monitoring module is specifically an OTDR signal monitoring module, and the pipe joint position mapping module is specifically a pipe joint position mapping module;

[0014] The laying method of the double-core sensing optical cable is as follows: a non-toxic, waterproof and good sealing waterproof glue is used to apply a certain stress to lay the double-core sensing optical cable in a straight line type inside the pipeline, and the sensing optical cable is fixed in a wave shape at both ends of the pipeline connection, the bending radius should be 15 times the radius of the optical cable, and the length d of the two optical cable fixing points at the bending laying position should be at least twice the spatial resolution of the signal monitoring module.

[0015] Preferably, in step S3, the process of detecting the optical fiber by the signal monitoring module and the pipe joint position mapping module is as follows: the signal monitoring module and the pipe joint position mapping module pass light into the optical fiber, the light is transmitted to the Faraday rotator mirror through the optical fiber, the Faraday rotator mirror acts as a strong reflection point to form reflected light transmitted back to the signal monitoring module and the pipe joint position mapping module, and the distance L1 between the head and the tail in the light intensity curve and the distance L2 between the head and the tail of the intermediate frequency signal are obtained according to the time of receiving the reflected light by the signal monitoring module and the pipe joint position mapping module, and when the optical propagation delay error caused by the double-core refractive index difference is uniformly distributed, the length ratio P of the two cores is L1: L2.

[0016] Preferably, in step S4, the specific process is as follows:

[0017] The operator taps the pipe section to form a vibration signal of the pipe section position, the vibration signal has an influence on the intermediate frequency signal, the intermediate frequency signal is converted into a time-space waterfall diagram, the position and distance of the vibration signal are obtained, the distance of different pipe sections from the starting point is finally positioned, and the different pipe sections are numbered in line.

[0018] Preferably, in the step S5, the specific process is as follows:

[0019] The effective characteristic parameter extraction module: according to the distance information of the pipe section from the starting point obtained in the step S4, the distance corresponding to the pipe section position in the light intensity curve is taken as a center point to perform forward difference calculation, the difference interval is d, and then the absolute value is taken to obtain a pipe section state curve T s ;

[0020] The misposition position and degree identification module: according to the light intensity curve superposition graph with time, a trend alarm threshold is set, a node where misposition of the pipeline may occur in the future is predicted, a large attenuation alarm threshold is set, and the light intensity attenuation point exceeding the threshold is a misposition occurrence point, and the misposition occurrence condition is judged according to the curve T s .

[0021] Therefore, the pipeline pipe section misposition analysis method based on distributed optical fiber sensing has the following advantages:

[0022] (1) In the present application, only one double-core sensing optical cable is needed to monitor the misposition of a large pipeline pipe section for a long time, which can not only guarantee the monitoring accuracy but also reduce the system cost. The sensing optical cable is arranged in a special way at the pipe section to enhance the stress change of the optical cable at the pipe section, and thus the light intensity change measured by the OTDR at this position is more obvious.

[0023] (2) The difference operation is introduced on the traditional OTDR curve, which simplifies the data analysis while taking into account the signal resolution,

[0024] (3) In the present application, the misposition of the pipeline is pre-alarmed by judging the light intensity change trend.

[0025] The technical solutions of the present application will be further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The detection structure block diagram in the pipeline pipe section misposition analysis method based on distributed optical fiber sensing of the present application;

[0027] Figure 2 The OTDR light intensity curve in the pipeline pipe section misposition analysis method based on distributed optical fiber sensing of the present application;

[0028] Figure 3The medium frequency signal diagram of the pipeline joint dislocation analysis method based on distributed optical fiber sensing of the present application;

[0029] Figure 4 The spatiotemporal waterfall diagram of the pipeline joint dislocation analysis method based on distributed optical fiber sensing of the present application;

[0030] Figure 5 The structure diagram of the sensing module of the pipeline joint dislocation analysis method based on distributed optical fiber sensing of the present application

[0031] Figure 6 The superposition diagram of the light intensity curve over time of the pipeline joint dislocation analysis method based on distributed optical fiber sensing of the present application;

[0032] Figure 7 The joint dislocation monitoring curve of the pipeline joint dislocation analysis method based on distributed optical fiber sensing of the present application. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. The specific specifications need to be selected and determined according to the actual specifications of the device, and the specific selection and calculation method adopts the existing technology in the field, so it will not be described in detail.

[0034] EMBODIMENT

[0035] The present application provides a pipeline joint dislocation analysis method based on distributed optical fiber sensing, comprising the following steps:

[0036] S1: A double-core sensing optical cable is laid on the inner side of the pipeline as a sensing module, a signal monitoring module, a joint position mapping module, a dislocation identification module and a visualization module are correspondingly arranged at the starting point of the pipeline, and a Faraday rotating mirror is arranged at the tail end of the pipeline; the specific arrangement is as shown in Figure 1

[0037] The signal monitoring module is specifically an OTDR signal monitoring module, and the joint position mapping module is specifically a joint position mapping module.

[0038] The double-core sensing optical cable is laid as shown in Figure 5 ​As shown, the double-core sensing optical cable is laid in a straight line inside the pipeline by applying stress with non-toxic and sealed waterproof glue, and the sensing optical cable is fixed in a wavy shape at both ends of the pipeline connection, and the bending radius should be 15 times the radius of the optical cable, and the length d of the two optical cable fixing points at the bending position should be at least twice the spatial resolution of the signal monitoring module, forming complete coverage of the pipeline by the double-core sensing optical cable, and the maximum strain of 0.5% to 1% can be applied to the optical fiber by the press machine and the tensioning equipment to ensure that the slight displacement of the pipe joint can cause a large change in the structural state of the optical cable at this position, thereby realizing the detection of the pipeline by the double-core sensing optical cable.

[0039] S2: The two optical fibers in the double-core sensing optical cable are connected to the signal monitoring module and the pipe joint position mapping module respectively, the signal monitoring module obtains the light intensity curve of the scattered light in the corresponding optical fiber, and the pipe joint position mapping module obtains the intermediate frequency signal of the scattered light in the corresponding optical fiber;

[0040] As shown in Figure 2 , the signal monitoring module obtains the light intensity curve of the corresponding optical fiber, and as shown in Figure 3 , the pipe joint position mapping module obtains the intermediate frequency signal of the corresponding optical fiber; the light intensity curve is the relationship between the light intensity and the starting distance, and the intermediate frequency signal is the relationship between the carrier signal strength and the starting distance;

[0041] S3: Faraday rotator mirrors are arranged at the tail ends of the two optical fibers; the signal monitoring module and the pipe joint position mapping module detect the optical fibers, and the length of the optical fibers is detected by the signal monitoring module and the pipe joint position mapping module through the Faraday rotator mirrors, and the length ratio P of the two optical fibers is obtained.

[0042] The specific detection process is as follows: the signal monitoring module and the pipe joint position mapping module pass light into the optical fiber, the light is transmitted to the Faraday rotator mirror through the optical fiber, the Faraday rotator mirror acts as a strong reflection point, and the reflected light is transmitted back to the signal monitoring module and the pipe joint position mapping module, and the distance L1 between the head and the tail in the light intensity curve and the distance L2 between the head and the tail in the intermediate frequency signal are obtained according to the time when the signal monitoring module and the pipe joint position mapping module receive the reflected light, and when the optical propagation time delay error caused by the double-core refractive index difference is uniformly distributed, the length ratio P of the two cores is L1:L2.

[0043] S4: The operator knocks the pipe joints connected to the pipeline in sequence, the pipe joints vibrate and form vibration signals, the pipe joint position mapping module acquires the intermediate frequency signal through the optical fiber, the vibration information at the pipe joint is attached to the intermediate frequency signal, the intermediate frequency signal changes, and the corresponding intermediate frequency signal is converted into a time-space waterfall diagram, as shown in Figure 4 , the relationship between the position and the distance of the vibration signal is obtained, and the distance of different pipe joints from the starting point of the pipeline is finally located, and the different pipe joints are numbered in sequence to locate the distance of different pipe joints from the starting point.

[0044] S5: The misalignment recognition module includes an effective feature parameter extraction module, a misalignment position and degree recognition module, combines the intermediate frequency signal, the light intensity curve and the proportional relationship P, forms a mapping relationship between the pipe joint position and the light intensity curve, and forms a pipeline state curve T s , and further recognizes the misalignment state of the pipeline;

[0045] Specifically as follows: according to the distance information of the pipe joint and the starting point obtained in step S4, as shown in the figure, Figure 6 The distance corresponding to the pipe joint position in the light intensity curve is calculated by forward difference, the difference interval is d, and then the absolute value is taken to obtain the pipe joint state curve T s , as shown in the figure, Figure 7 Here, according to the positioning of the pipe joint, the light intensity change at the pipe joint position is determined to form the pipe joint state curve, the vertical axis is the light intensity change, that is, the misalignment degree, and the horizontal axis is the number of pipe joints,

[0046] Misalignment position and degree recognition module: due to the light intensity attenuation caused by fiber aging and slow evolution of geology, light intensity attenuation occurs at T99, a trend alarm threshold is set according to the light intensity curve superimposed with time, a node where pipeline misalignment may occur in the future is predicted, a large attenuation alarm threshold is set, and the light intensity attenuation point exceeding the threshold is the misalignment occurrence point, and the misalignment occurrence condition is judged according to the curve T s

[0047] S6: The pipeline state is displayed through a visualization module, and the display content includes but is not limited to pipe joint misalignment position, light intensity curve, cable skin length and pipe joint position mapping data.

[0048] Through regular pipeline surface cable data acquisition, monitoring and data analysis, changes and abnormal conditions of the pipeline health condition are detected, an abnormal alarm threshold is set, periodic response and necessary pipeline maintenance and repair measures are taken to ensure the safe operation of the pipeline.

[0049] In the subsequent actual detection process, the pipe joint position mapping module can be removed, and single-core detection is performed through the signal monitoring module, because the pipe joint position mapping module is mainly used for positioning the pipe joint position, rather than for detection.

[0050] Therefore, the present application adopts a pipeline pipe joint misalignment analysis method based on distributed optical fiber sensing, and faces the problems of difficult large pipeline misalignment detection, inconvenient operation and the like, utilizes optical fiber sensing technology to detect the misalignment of the pipeline, utilizes the pre-embedded sensing cable in the pipeline as a sensor, and then demodulates and analyzes the collected signals through distributed optical fiber sensing technology, realizes high-precision misalignment monitoring and health state evaluation of the pipeline, and further ensures the safety of water resource transportation.

[0051] ​It should be pointed out finally that the above examples are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A pipeline segment misalignment analysis method based on distributed optical fiber sensing, characterized by: The following steps are involved: S1: A dual-core optical fiber sensor cable is laid inside the pipeline as a sensing module. A signal monitoring module, a pipe segment position mapping module, a misalignment identification module, and a visualization module are installed at the starting point of the pipeline. A Faraday rotator is installed at the end of the pipeline. S2: The two optical fibers in the dual-core sensor cable are connected to the signal monitoring module and the pipe joint position mapping module respectively. The signal monitoring module obtains the light intensity curve of the scattered light in the corresponding optical fiber, and the pipe joint position mapping module obtains the intermediate frequency signal of the scattered light in the corresponding optical fiber. S3: A Faraday rotator is provided at the end of each of the two optical fibers; a signal monitoring module and a tube position mapping module detect the optical fibers, and the length of the optical fibers is detected by the Faraday rotator using the signal monitoring module and the tube position mapping module to obtain a length ratio P of the two optical fibers; S4: The operator knocks on the pipe joints of the pipeline in sequence, causing them to vibrate. The pipe joint position mapping module collects intermediate frequency signals through optical fibers. The vibration information of the pipe joint is attached to the intermediate frequency signal and used to locate the distance between the pipe joint and the starting point. S5: The dislocation recognition module includes an effective feature parameter extraction module and a dislocation position and degree recognition module. It combines the intermediate frequency signal, the light intensity curve and the proportional relationship P to form a mapping relationship between the pipe joint position and the light intensity curve, and forms a pipeline status curve T s , and then identify the misalignment status of the pipeline; S6: The pipeline status is displayed through the visualization module, including but not limited to the pipe segment misalignment position, the current light intensity curve, and the mapping data between the optical cable sheath length and the pipe segment position.

2. The method for analyzing pipeline segment misalignment based on distributed optical fiber sensing according to claim 1, characterized in that: In step S1, the specific settings are as follows The signal monitoring module is specifically an OTDR signal monitoring module, and the pipe segment position mapping module is specifically -OTDR pipe segment position mapping module; The laying method of the dual-core sensor optical cable is as follows: use non-toxic, well-sealed waterproof glue to apply a certain stress to lay the dual-core sensor optical cable in a straight line inside the pipeline. At both ends of the pipeline connection, the sensor optical cable is laid and fixed in a wavy bend. The bending radius should be 15 times the radius of the optical cable. The length d of the two optical cable fixing points at the bending layout should be at least twice the spatial resolution of the signal monitoring module.

3. The method for analyzing pipeline segment misalignment based on distributed optical fiber sensing according to claim 1, characterized in that: In step S3, the process of the signal monitoring module and the tube position mapping module detecting the optical fiber is as follows: the signal monitoring module and the tube position mapping module allow light to pass into the optical fiber, and the light is transmitted to the Faraday rotator through the optical fiber. The Faraday rotator acts as a strong reflection point to form reflected light that is transmitted back to the signal monitoring module and the tube position mapping module. According to the time when the signal monitoring module and the tube position mapping module receive the reflected light, the distance L1 between the head end and the tail end in the light intensity curve and the distance L2 between the head end and the tail end of the intermediate frequency signal are obtained. When the light propagation delay error caused by the difference in the refractive index of the dual cores is evenly distributed, the length ratio P of the two fiber cores is specifically L1:L2.

4. The method for analyzing pipeline segment misalignment based on distributed optical fiber sensing according to claim 1, characterized in that: In step S4, the specific process is as follows: The operator knocks on the pipe joint, generating a vibration signal at the pipe joint position. The vibration signal affects the intermediate frequency signal, which is converted into a time-space waterfall diagram to obtain the relationship between the position and distance of the vibration signal. Finally, the distance between different pipe joints and the starting point is located, and the different pipe joints are numbered according to the row.

5. The method for analyzing pipeline segment misalignment based on distributed optical fiber sensing according to claim 1, characterized in that: In step S5, the specific process is as follows: Effective feature parameter extraction module: According to the distance information between the pipe segment and the starting point obtained in step S4, the distance corresponding to the pipe segment position in the light intensity curve is used as the center point for forward difference calculation, the difference interval is d, and then the absolute value is taken to obtain the pipe segment state curve T s ; Dislocation position and degree identification module: set the trend alarm threshold according to the light intensity curve over time, predict the nodes where pipeline dislocation may occur in the future, set the maximum attenuation alarm threshold, and the light intensity attenuation point exceeding the threshold is the dislocation occurrence point. s Determine if misalignment occurs.

Images