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

Abstract

The invention discloses a pipeline joint dislocation analysis method based on distributed optical fiber sensing, and belongs to the technical field of pipeline detection. Comprising 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, wherein the sensing module is a double-core sensing optical cable arranged in a pipeline by a special method; the optical cable calibration module calculates the length proportional relation of the two fiber cores; the signal monitoring module is used for collecting light intensity signals of an optical cable. The pipe joint position mapping module is used for temporarily deploying and establishing mapping between the light intensity curve and the actual position of the pipe joint; and the dislocation identification module is used for excavating effective characteristic parameters from the light intensity curve so as to identify the dislocation position and degree of the pipe joint. And the visualization module is used for visually displaying a pipeline dislocation state identification result to an operator. According to the method, the sensing optical cable pre-buried in the pipeline is used as a sensor, and the optical fiber sensing technology is used for conducting dislocation detection on the pipeline.

Description

Technical Field

[0001] The invention 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 Art

[0002] Large water pipelines are a core component 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 changes in internal pressure, resulting in dislocation and deformation. These phenomena often originate from the formation of cavities caused by geological disasters, or significant differences in soil conditions along the pipeline when it is laid, resulting in uneven stress on the pipeline. The burst time of such pipeline dislocation is sudden, which may lead to water supply interruption and cause serious secondary disasters. The water flow generated after the burst may erode surrounding roads and buildings, causing collapse, traffic jams, and even casualties, resulting in significant economic losses and negative social impacts.

[0003] Traditional detection methods mainly include visual inspection, acoustic detection and manual excavation. Although these methods are effective in some cases, they often rely on regular inspections and are difficult to achieve real-time monitoring. Manual excavation methods are destructive and can usually only sample and verify a small number of pipes. They are inefficient, costly, and affect the normal water delivery function. Summary of the invention

[0004] The purpose of the present invention is to provide a pipeline joint misalignment analysis method based on distributed optical fiber sensing. In the face of the problems of difficult large-scale pipeline misalignment detection and inconvenient operation, optical fiber sensing technology is used to detect pipeline misalignment, and the pre-buried sensing optical cable in the pipeline is used as a sensor. The collected signal is demodulated and analyzed through distributed optical fiber sensing technology, thereby achieving high-precision misalignment monitoring and health status assessment of the pipeline, thereby ensuring the safety of water resource transportation.

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

[0006] S1: A dual-core sensing optical cable is laid on the inner side of 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 set at the starting point of the pipeline, and a Faraday rotating mirror is set at the tail end of the pipeline;

[0007] S2: The two optical fibers in the dual-core sensing optical cable are respectively connected to the signal monitoring module and the pipe joint position mapping module. The signal detection 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.

[0008] S3: A Faraday rotator is provided at the tail end of the two optical fibers; the signal monitoring module and the tube position mapping module detect the optical fiber, and the length of the optical fiber is detected by the Faraday rotator using the signal monitoring module and the tube position mapping module to obtain the length ratio relationship P of the two optical fibers;

[0009] S4: The operator knocks on the pipe joints of the pipeline in turn, causing the pipe joints to vibrate. The pipe joint position mapping module collects intermediate frequency signals through optical fibers. The vibration information at the pipe joints is attached to the intermediate frequency signals and is used to locate the distance between the pipe joints and the starting point.

[0010] 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 state curve T s , and then identify the misalignment status of the pipeline;

[0011] S6: The pipeline status is displayed through a 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.

[0012] Preferably, in step S1, the specific settings are as follows

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

[0014] 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. The sensor optical cable is laid and fixed in a wavy shape at both ends of the pipeline connection. 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 location is at least twice the spatial resolution of the signal monitoring module.

[0015] Preferably, in step S3, the process of the signal monitoring module and the tube-joint position mapping module detecting the optical fiber is as follows: the signal monitoring module and the tube-joint 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-joint position mapping module. According to the time when the signal monitoring module and the tube-joint 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 uniformly distributed, the length ratio P of the two fiber cores is specifically L1:L2.

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

[0017] The operator knocks on the pipe joint to form 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.

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

[0019] Effective feature parameter extraction module: According to the distance information between the tube segment and the starting point obtained in step S4, the distance corresponding to the tube 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 tube segment state curve T s ;

[0020] 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 point. s Determine the occurrence of misalignment.

[0021] Therefore, the present invention adopts the above-mentioned pipeline segment misalignment analysis method based on distributed optical fiber sensing, which has the following advantages:

[0022] (1) In the present invention, only one dual-core sensing optical cable is needed to monitor the misalignment of a large pipeline section for a long time, which can not only ensure the monitoring accuracy but also reduce the system cost. The sensing optical cable is laid out at the pipe section in a special way to enhance the stress change of the optical cable at the pipe section, thereby making the light intensity change measured by the OTDR at this location more obvious.

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

[0024] (3) In the present invention, early warning of pipeline misalignment is achieved by judging the trend of light intensity changes.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A detection structure framework diagram of a pipeline segment misalignment analysis method based on distributed optical fiber sensing according to the present invention;

[0027] Figure 2 It is an OTDR light intensity curve diagram in a pipeline pipe section misalignment analysis method based on distributed optical fiber sensing of the present invention;

[0028] Figure 3It is an intermediate frequency signal diagram of a pipeline segment misalignment analysis method based on distributed optical fiber sensing according to the present invention;

[0029] Figure 4 A time-space waterfall diagram for positioning in a pipeline segment misalignment analysis method based on distributed optical fiber sensing according to the present invention;

[0030] Figure 5 This is a structural diagram of a sensing module in a pipeline segment misalignment analysis method based on distributed optical fiber sensing according to the present invention.

[0031] Figure 6 It is a superposition diagram of light intensity curves over time in a pipeline pipe segment misalignment analysis method based on distributed optical fiber sensing of the present invention;

[0032] Figure 7 The present invention discloses a pipe segment misalignment monitoring curve in a pipeline pipe segment misalignment analysis method based on distributed optical fiber sensing. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. The specific model specifications need to be selected and determined according to the actual specifications of the device, and the specific selection calculation method adopts the existing technology in the field, so it will not be described in detail.

[0034] Example

[0035] The present invention provides a pipeline segment misalignment analysis method based on distributed optical fiber sensing, comprising the following steps:

[0036] S1: A dual-core sensor optical cable is laid on the inner side of the pipeline as a sensor module, a signal monitoring module, a pipe segment position mapping module, a misalignment recognition module and a visualization module are set at the starting point of the pipeline, and a Faraday rotating mirror is set at the end of the pipeline; the specific settings are as follows: Figure 1 As shown;

[0037] The signal monitoring module is specifically an OTDR signal monitoring module, and the pipe segment position mapping module is specifically Pipe segment position mapping module;

[0038] The layout of the dual-core sensor optical cable is as follows: Figure 5As shown, a non-toxic, well-sealed waterproof glue is used to apply a certain stress to lay the dual-core sensing optical cable in a straight line inside the pipeline. The sensing optical cable is fixed in a wavy bend at both ends of the pipeline connection. 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, forming a complete coverage of the pipeline by the dual-core sensing optical cable. The maximum tolerable strain of 0.5% to 1% can also be applied to the optical fiber through a press and tensioning equipment to ensure that a slight displacement of the pipe section can cause a significant change in the structural state of the optical cable at that location, thereby realizing the detection of the pipeline by the dual-core sensing optical cable.

[0039] S2: The two optical fibers in the dual-core sensing optical cable are respectively connected to the signal monitoring module and the pipe joint position mapping module. The signal detection 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] like Figure 2 As shown, the signal detection module obtains the light intensity curve of the corresponding optical fiber, such as Figure 3 As shown, the tube position mapping module obtains the intermediate frequency signal of the corresponding optical fiber; the light intensity curve is specifically the relationship between the light intensity and the starting point distance, and the intermediate frequency signal is specifically the relationship between the carrier signal intensity and the starting point distance;

[0041] S3: A Faraday rotator is provided at the tail end of the two optical fibers; the signal monitoring module and the tube position mapping module detect the optical fiber, and the length of the optical fiber is detected by the Faraday rotator using the signal monitoring module and the tube position mapping module to obtain the length ratio relationship P of the two optical fibers;

[0042] The specific detection process is as follows: the signal monitoring module and the tube position mapping module pass light 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 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. 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.

[0043] S4: The operator knocks on the pipe joints of the pipeline in turn, and the pipe joints vibrate and form vibration signals. The pipe joint position mapping module collects the intermediate frequency signal through the optical fiber. The vibration information at the pipe joint is attached to the intermediate frequency signal, causing the intermediate frequency signal to change. The corresponding intermediate frequency signal is converted into a time-space waterfall diagram, such as Figure 4 As shown, the relationship between the position and distance of the vibration signal is obtained, and finally the distance between different pipe sections and the starting point of the pipeline is located, and different pipe sections are numbered according to the row to locate the distance between different pipe sections and the starting point;

[0044] 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 state curve T s , and then identify the misalignment status of the pipeline;

[0045] The details are as follows: According to the distance information between the pipe segment and the starting point obtained in step S4, Figure 6 As shown, the distance corresponding to the tube position in the light intensity curve is taken as the center point for forward difference calculation, the difference interval is d, and then the absolute value is taken to obtain the tube state curve T s ,like Figure 7 As shown, here, according to the positioning of the pipe segment, the light intensity change at the position of the pipe segment is determined to form a pipe segment state curve. The vertical axis is the change in light intensity, that is, the degree of misalignment, and the horizontal axis is the number of the pipe segment.

[0046] Dislocation position and degree identification module: Due to the light intensity attenuation caused by optical fiber aging and slow geological evolution, light intensity attenuation begins to occur at time T99. The trend alarm threshold is set according to the light intensity curve over time superposition diagram to predict the nodes where pipeline dislocation may occur in the future. The maximum attenuation alarm threshold is set. The light intensity attenuation point exceeding the threshold is the dislocation occurrence point. According to the curve T s Determine the occurrence of misalignment;

[0047] S6: The pipeline status is displayed through a visualization module, and the displayed content includes but is not limited to the pipe segment misalignment position, light intensity curve, optical cable sheath length and pipe segment position mapping data, etc.

[0048] By regularly collecting, monitoring and analyzing optical cable data on the pipeline surface, changes and abnormal conditions in the pipeline health status are detected, abnormal alarm thresholds are set, and necessary pipeline maintenance and repair measures are taken periodically 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 can be performed through the signal monitoring module, because the pipe joint position mapping module is mainly used to locate the pipe joint position rather than for detection.

[0050] Therefore, the present invention adopts a pipeline pipe segment misalignment analysis method based on distributed optical fiber sensing. In the face of the problems of difficult large-scale pipeline misalignment detection and inconvenient operation, optical fiber sensing technology is used to detect pipeline misalignment, and the pre-buried sensing optical cable in the pipeline is used as a sensor. The collected signal is demodulated and analyzed through distributed optical fiber sensing technology, thereby achieving high-precision misalignment monitoring and health status assessment of the pipeline, thereby ensuring the safety of water resource transportation.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A pipeline segment misalignment analysis method based on distributed optical fiber sensing, characterized in that: The following steps are involved: S1: A dual-core sensing optical cable is laid on the inner side of 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 set at the starting point of the pipeline, and a Faraday rotating mirror is set at the tail end of the pipeline; S2: The two optical fibers in the dual-core sensing optical cable are respectively connected to the signal monitoring module and the pipe joint position mapping module. The signal detection 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 tail end of the two optical fibers; the signal monitoring module and the tube position mapping module detect the optical fiber, and the length of the optical fiber is detected by the Faraday rotator using the signal monitoring module and the tube position mapping module to obtain the length ratio relationship P of the two optical fibers; S4: The operator knocks on the pipe joints of the pipeline in turn, causing the pipe joints to vibrate. The pipe joint position mapping module collects intermediate frequency signals through optical fibers. The vibration information at the pipe joints is attached to the intermediate frequency signals and is used to locate the distance between the pipe joints 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 state curve T s , and then identify the misalignment status of the pipeline; S6: The pipeline status is displayed through a 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 pipeline segment misalignment analysis method based on distributed optical fiber sensing according to claim 1 is 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 location 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. The sensor optical cable is laid and fixed in a wavy shape at both ends of the pipeline connection. 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 location is at least twice the spatial resolution of the signal monitoring module.

3. The pipeline segment misalignment analysis method based on distributed optical fiber sensing according to claim 1 is 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 rotation mirror through the optical fiber. The Faraday rotation mirror serves 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 pipeline segment misalignment analysis method based on distributed optical fiber sensing according to claim 1 is characterized in that: In step S4, the specific process is as follows: The operator knocks on the pipe joint to form 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 pipeline segment misalignment analysis method based on distributed optical fiber sensing according to claim 1 is characterized in that: In step S5, the specific process is as follows: Effective feature parameter extraction module: According to the distance information between the tube segment and the starting point obtained in step S4, the distance corresponding to the tube 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 tube 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 point. s Determine the occurrence of misalignment.

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