CN111750790A - Pipeline two-dimensional deformation monitoring method based on distributed optical fiber - Google Patents
Pipeline two-dimensional deformation monitoring method based on distributed optical fiber Download PDFInfo
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- CN111750790A CN111750790A CN202010320910.3A CN202010320910A CN111750790A CN 111750790 A CN111750790 A CN 111750790A CN 202010320910 A CN202010320910 A CN 202010320910A CN 111750790 A CN111750790 A CN 111750790A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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Abstract
The invention relates to a distributed optical fiber-based pipeline two-dimensional deformation monitoring method, which comprises the following steps: 1) symmetrically sticking the distributed strain monitoring optical cables on the upper surface and the lower surface of the pipeline, and respectively connecting the two optical cables to demodulation equipment; 2) respectively reading strain information measured by optical cables on the upper surface and the lower surface of the pipeline through demodulation equipment; 3) averagely dividing the pipeline into a plurality of sections, and respectively calculating the deformation condition of each section; 4) assuming that the initial end is not inclined, calculating the displacement of the tail end of the first section of the pipeline through a geometric relation; 5) calculating the displacement of the tail end of the second section based on the displacement of the tail end of the first section; 6) similarly, the displacement of the tail end of each section is obtained by the method in the step 5); 7) and superposing the displacement of each section, so that the deformation condition of the whole section of pipeline can be calculated. The method simplifies the pipeline into an Euler Bernoulli beam model, and calculates the deformation condition of the whole pipeline through strain data measured by the distributed optical fiber.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to a pipeline two-dimensional deformation monitoring method based on distributed optical fibers.
Background
The pipeline transportation has obvious advantages, and people can not leave the pipeline in production and life. However, due to the corrosion of natural environment and transport medium, the flaw of materials and construction, the damage of human construction excavation and the influence of natural disasters such as earthquake, the pipeline can be leaked, burst and even exploded. Besides considering the serious economic loss caused by the leakage or pipe explosion of the pipeline, the leakage or pipe explosion of the pipeline can cause the leakage of harmful substances, pollute the environment and even cause poisoning and explosion accidents, thus endangering the personal safety. Therefore, the early leakage monitoring of the pipeline and the early warning of geological disasters, machinery, manual construction, even malicious pipeline damage and perforation and theft behaviors which endanger the safety of the pipeline are very important. Traditional leakage monitoring method can not monitor the pipeline and leak, more can't judge leakage point position and region to can not carry out real-time supervision and early warning to dangerous event that harm pipeline safety such as various natural disasters, mechanical operation and manual operation, in addition, the monitoring of the pipe safety hidden danger exists among the prior art not enough to have: the point type sensor can not meet the requirement of long-distance pipeline safety monitoring; the sensor needs power supply and is not suitable for leakage monitoring of pipelines with flammability, explosiveness and the like.
The distributed optical fiber sensing monitoring technology is a novel sensing technology which utilizes sensing optical fibers as monitoring elements and signal transmission media, and has the advantages of small size, light weight, electromagnetic interference resistance, corrosion resistance, high sensitivity, high measuring speed, long service life, low cost and the like, so that an effective pipeline deformation monitoring method and an effective pipeline deformation monitoring system can be established based on the distributed optical fiber sensors. Aiming at a liquid conveying pipeline commonly used in engineering, an Euler-Bernoulli beam is used as a model, a proper coordinate system is selected to establish an accurate geometric model, simplification is performed on the basis, and a two-dimensional deformation algorithm with high calculation efficiency and relatively accurate result is obtained under the condition of meeting the calculation accuracy, so that the method becomes a key point for solving the pipeline deformation problem.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a two-dimensional deformation monitoring method based on distributed optical fibers in view of the prior art, the pipeline is simplified into an Euler Bernoulli beam model, and the deformation condition of the whole pipeline is obtained through calculation according to strain data measured by the distributed optical fibers.
The technical scheme adopted by the invention for solving the problems is as follows: a distributed optical fiber-based pipeline two-dimensional deformation monitoring method comprises the following steps:
1) symmetrically sticking the distributed strain monitoring optical cables on the upper surface and the lower surface of the pipeline, and respectively connecting the two optical cables to demodulation equipment;
2) respectively reading strain information measured by optical cables on the upper surface and the lower surface of the pipeline through demodulation equipment;
3) averagely dividing the pipeline into a plurality of sections, and respectively calculating the deformation condition of each section;
4) assuming that the initial end is not inclined, calculating the displacement of the tail end of the first section of the pipeline through a geometric relation;
5) calculating the displacement of the tail end of the second section based on the displacement of the tail end of the first section;
6) similarly, the displacement of the tail end of each section is obtained by the method in the step 5);
7) and superposing the displacement of each section, so that the deformation condition of the whole section of pipeline can be calculated.
2. The method for monitoring the two-dimensional deformation of the pipeline based on the distributed optical fiber according to claim 1, wherein the method comprises the following steps: in step 4), the displacement of the end of the first section of the pipeline is calculated by the following formula:
in the formula, R1Is the radius of curvature of the first section of the pipe unit, r is the radius of the cross section of the pipe, theta1Is the corresponding central angle of the first section of the pipeline unit,on the upper partThe strain value measured by the strain optical cable at the upper end of the pipeline,lower partStrain value measured for the strain optical cable at the lower end of the pipeline;
in the step 5), the displacement of the tail end of the second section of the pipeline is calculated by the following formula:
in the formula, R2Is the radius of curvature, theta, of the second section of the pipe element2The central angle is corresponding to the second section of pipeline unit;
in the step 6), the displacement of the tail end of the nth section of the pipeline is calculated by the following formula:
in the step 7), the deflection of any point of the two-dimensional pipeline is calculated by the following formula:
compared with the prior art, the invention has the advantages that:
(1) for the pipeline which is easy to deform in a vertical plane, the algorithm of the invention is simple and the calculation efficiency is high.
(2) And in the monitoring process, only two optical cables are laid at the upper end and the lower end of the pipeline, so that the installation is simple and easy.
(3) The method has the advantages of sufficient theoretical basis, higher coincidence degree of the calculation result and the actual situation, and certain engineering significance.
Drawings
FIG. 1 is a diagram of the position of a cable at the surface of a conduit in an embodiment of the present invention.
FIG. 2 is a schematic view of a first section of a pipe of the present invention.
FIG. 3 is a schematic diagram of the infinitesimal deformation of the nth segment of the pipeline in the embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
The embodiment provides a distributed optical fiber-based pipeline two-dimensional deformation monitoring method, which comprises the following steps:
(1) symmetrically sticking the distributed strain monitoring optical cables to the upper surface and the lower surface of the pipeline (figure 1), and respectively connecting the two optical cables to demodulation equipment;
(2) respectively reading strain information measured by optical cables on the upper surface and the lower surface of the pipeline through demodulation equipmentOn the upper partAndlower part，On the upper partThe strain value measured by the strain optical cable at the upper end of the pipeline,lower partStrain value measured for the strain optical cable at the lower end of the pipeline;
(3) averagely dividing the pipeline into a plurality of sections, and respectively calculating the deformation condition of each section;
(4) assuming that the initial segment is not inclined, that is, the initial segment is in a horizontal state, the displacement of the end of the first segment of the pipeline is calculated through a geometric relationship (fig. 2), and the specific calculation process is as follows:
respectively measuring strain values of the upper surface and the lower surface of the pipeline through the strain optical cable, setting the resolution of the strain optical cable as l, and analyzing a unit (according to each section of the section) with the length of l, wherein the deformation condition of the unit is shown in figure 2:
wherein l is unit original length l'On the upper partIs the length of the upper surface of the unit after deformation of l'Lower partThe length of the lower surface of the deformed unit is equal to the height of the cross section of the beam of 2R, the shape of the deformed unit is calculated according to the shape of an arc, the radius of the arc is R, and the corresponding central angle is theta.
The euler-bernoulli beam model is used, i.e. the cross section is perpendicular to the central axis after deformation, without considering the shearing effect.
Measuring upper surface strain by strain cableOn the upper partStrain of lower surfaceLower part。
l'On the upper part＝On the upper partl+l＝(On the upper part+1)l (2)
All are l'Lower part＝Lower partl+l＝(Lower part+1)l (3)
∴θ·R＝(On the upper part+1)l (5)
For the same reason, θ (R-2R) ═ c (Lower part+1)l (6)
The formula (5) and (6) are solved:
let the perpendicular distance between the end of each segment and the axis of the original position be T
(5) Calculating the second segment end displacement (FIG. 3) for the second segment unit based on the first segment end displacement
Wherein: theta2Corresponding chord length m2Comprises the following steps:
(6) similarly, for the nth unit, the vertical distance between the end point and the axis of the original position is Tn。
It is easy to deduce that:
......
substituting the formula (7) and (8) into the formula (15) to obtain:
(7) and superposing the displacement of each section, so that the deformation condition of the whole section of pipeline can be calculated, and finally, the deflection of any point of the two-dimensional pipeline can be obtained according to the following formula:
the strain data measured after dividing a pipe into 50 sections is shown in the following table:
TABLE 1 Strain data
In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.
Claims (2)
1. A pipeline two-dimensional deformation monitoring method based on distributed optical fibers is characterized by comprising the following steps: the method comprises the following steps:
1) symmetrically sticking the distributed strain monitoring optical cables on the upper surface and the lower surface of the pipeline, and respectively connecting the two optical cables to demodulation equipment;
2) respectively reading strain information measured by optical cables on the upper surface and the lower surface of the pipeline through demodulation equipment;
3) averagely dividing the pipeline into a plurality of sections, and respectively calculating the deformation condition of each section;
4) assuming that the initial end is not inclined, calculating the displacement of the tail end of the first section of the pipeline through a geometric relation;
5) calculating the displacement of the tail end of the second section based on the displacement of the tail end of the first section;
6) similarly, the displacement of the tail end of each section is obtained by the method in the step 5);
7) and superposing the displacement of each section, so that the deformation condition of the whole section of pipeline can be calculated.
2. The method for monitoring the two-dimensional deformation of the pipeline based on the distributed optical fiber according to claim 1, wherein the method comprises the following steps: in step 4), the displacement of the end of the first section of the pipeline is calculated by the following formula:
in the formula, R1Is the radius of curvature of the first section of the pipe unit, r is the radius of the cross section of the pipe, theta1Is a first section of pipeThe central angle corresponding to the road unit is,on the upper partThe strain value measured by the strain optical cable at the upper end of the pipeline,lower partStrain value measured for the strain optical cable at the lower end of the pipeline;
in the step 5), the displacement of the tail end of the second section of the pipeline is calculated by the following formula:
in the formula, R2Is the radius of curvature, theta, of the second section of the pipe element2The central angle is corresponding to the second section of pipeline unit;
in the step 6), the displacement of the tail end of the nth section of the pipeline is calculated by the following formula:
in the step 7), the deflection of any point of the two-dimensional pipeline is calculated by the following formula:
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113739705A (en) * | 2021-08-30 | 2021-12-03 | 武汉地震工程研究院有限公司 | Method for monitoring transverse displacement of member based on segmented arc splicing algorithm |
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Effective date of registration: 20211111 Address after: 214400 No. 278, Chengjiang Middle Road, high tech Zone, Jiangyin City, Wuxi City, Jiangsu Province Applicant after: JIANGSU FASTEN OPTOELECTRONICS TECHNOLOGY Co.,Ltd. Address before: 214400 No. 278, Chengjiang Middle Road, high tech Zone, Jiangyin City, Wuxi City, Jiangsu Province Applicant before: JIANGSU FASTEN OPTOELECTRONICS TECHNOLOGY Co.,Ltd. Applicant before: WUXI FASTEN OPTOELECTRONICS TECHNOLOGY Co.,Ltd. Applicant before: FASTEN GROUP Co.,Ltd. |
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