CN106931896B - Optical fiber sensing technology and system for deformation monitoring of geomembrane anti-seepage earth-rock dam - Google Patents
Optical fiber sensing technology and system for deformation monitoring of geomembrane anti-seepage earth-rock dam Download PDFInfo
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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
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
- G01B11/162—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means by speckle- or shearing interferometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Abstract
The distributed optical fiber sensing system and the technical scheme can realize the networking, integrated online remote measurement and large-range multi-parameter space-time full coverage of geomembrane bidirectional strain and joint fracture opening of the geomembrane anti-seepage earth-rock dam of the dam, and obviously improve the technological content and the efficiency of safety monitoring of the geomembrane anti-seepage earth-rock dam. Provides a special wide-range combined sensing optical fiber consisting of an SM tight-sleeved optical fiber, a carbon-coated SM optical fiber and a fluorinated plastic optical fiber, and a matched BOTDA type and OTDR type optical signal demodulator. The strain range of the strain gauge reaches 40%, and particularly, the strain gauge can simultaneously monitor the occurrence, the position and the opening degree of the geomembrane joint fracture, so that the upgrading and the updating of the conventional point type electric strain gauge of the geomembrane are realized, and the blank and the problem of joint fracture monitoring are particularly broken through. The arrangement mode of the orthogonal sensor network, the optical fiber laying, positioning and consolidating process and the method for establishing the initial field of the optical fiber network are provided, and the method has engineering practicability.
Description
Distributed Optic-Fiber Sensing Technology and System
for Monitoring of Deformation of GeomembraneAnti-seepage Earth-Rockfill Dam
Technical Field
The invention relates to a distributed optical fiber sensing monitoring system and a technical scheme for geomembrane strain and seam fracture of a geomembrane anti-seepage earth-rock dam, which can realize large-range and multifunctional online remote sensing of distributed optical fiber sensing of geomembrane bidirectional strain and seam fracture opening of the geomembrane anti-seepage earth-rock dam, obtain reliable observation results and realize quantitative-positioning and timely early warning.
Background
Development of geomembrane anti-seepage type earth-rock dam
Earth-rock dams in dam engineering are widely applied, and earth impervious dam shapes and concrete slab dam shapes are mainly used so far. In recent years, with the development of high polymer materials, particularly the accumulation of seepage prevention application and practical experience of geomembrane in dam seepage prevention, the geomembrane has the advantages of strong and durable seepage prevention performance, low manufacturing cost, quick construction, high social and economic value potential and rapid development of the abnormal military prominence. Internationally, the highest geomembrane seepage-proofing earth-rock dam is a Poza de Los Ramos dam built in 1948 in Spain, the height is 97m, the height is increased to 134m after the operation for more than 60 years, and a 160m high dam of the dam type is also built. National industry specifications of Polyethylene (PE) geomembrane anti-seepage engineering technical specification (SL/T231-98) and water and electricity engineering geomembrane anti-seepage technical specification (NB/T35027-.
Safety monitoring of deformation of geomembrane anti-seepage system
Since geomembrane seepage prevention is a new earth-rock dam type protruding from the army in the present generation, the practical experience accumulation is less (particularly high dam engineering), so that the safety monitoring of the dam type is very important, the actual working state of the dam can be timely and reliably mastered, countermeasures can be adopted, the safety of the dam can be ensured, and valuable data and basis are provided for the development of the dam type.
It is easy to see that in the dam type, the weakest link of strength and seepage-proofing performance in the geomembrane seepage-proofing system is the joint of the geomembrane. The drainage of the earth-rock dam of the pier reservoir in Zhejiang is detected by emptying inspection, namely the leakage of water due to local cracking of joints [ Li xing, design and construction of composite earth-rock dam geomembrane seepage-proofing inclined wall, Earth-rock dam technology-2005 research and literature collection, Beijing: china electric power press ]. In high dam engineering, the common PE (polyethylene (including HDPE (high density polyethylene)) used as the geomembrane material is welded joints for splicing seams, so that the breakage of PE welding joints and the breakage of geomembrane defect repair are the key points of seepage-proofing damage and leakage dangerous situations of a dam body, and the tensile strain capacity of the geomembrane is a characteristic index of the working state of the geomembrane.
Geomembrane strain monitoring conventional instruments have heretofore adopted geomembrane strain gauges. The resistance type strain gauge with a large strain range (such as specially-made constantan) has the limitations of a point type electrical measurement sensing instrument, the monitoring range is small, the space discreteness of data is caused, the durability of the resistance type strain gauge is obviously influenced by the submergence of high-pressure water, and the resistance type strain gauge without fault working time difference is satisfactory. Monitoring of geomembrane seams and defect repair fracture openings is blank so far.
Distributed fiber optic sensing has no precedent for PE geomembrane strain Monitoring, but there are efforts to use geotextile strain detection [ Liehr S. et al. Polymer optical fiber Sensor for Distributed structured analysis and Application in structured Health Monitoring, IEED Sensors J.,9 (11), 1330-1338 (2009) ]. POF (plastic optical fiber) is adopted to adapt to the characteristic of large deformation of the geotextile, and the optical fiber is woven into the geotextile to be woven into a whole. The optical measurement is performed by OTDR (optical time domain reflectometer) based on the rayleigh scattering light reflection principle. The on-way loss of a POF is positively correlated to its tensile strain value.
At present, the distributed optical fiber sensing technology system has no achievements and examples for geomembrane strain and seam fracture opening degree. However, in the field of concrete engineering structures, distributed optical fiber sensing technologies, systems and engineering examples for monitoring concrete strain and cracks based on BOTDA (Brillouin optical time domain analysis) have been developed at home and abroad. The distribution of tensile strain in concrete cracks and adjacent places is in an obvious hump shape, so that the occurrence time, the positions and the crack width of the cracks can be determined.
In view of the above, aiming at the specific requirements of geomembrane strain and seam fracture opening monitoring of geomembrane anti-seepage earth-rock dam engineering, the invention provides a multifunctional (geomembrane strain-seam and defect repair fracture opening) distributed optical fiber sensing monitoring system and a technical scheme, which are suitable for geomembrane strain and seam fracture opening monitoring of geomembrane anti-seepage earth-rock dams, by comprehensively utilizing high-end achievements in the current distributed optical fiber sensing field.
Disclosure of Invention
Scientific principle based on technical scheme
(1) The optical principle is as follows:
two intrinsic scatterings of the optical fiber and the optical waveguide, namely Brillouin scattering and Rayleigh scattering, are sensitive to two mechanical quantities, namely temperature and strain. The two intrinsic scatters have respective optical parameters, which become strain and temperature information carriers as follows:
1) brillouin scattering light-the frequency shift of the peak of the Brillouin gain spectrum is linearly related to the temperature and the strain increment, and the basic relation is as follows
In the formula, △ vbFor the Brillouin gain spectral shift, △ ε is the strain increase, △ T is the temperature increase, C11Is the Brillouin strain-frequency coefficient, C12Is the brillouin temperature-frequency coefficient. The strain and the temperature of the optical fiber can be measured by measuring the Brillouin frequency shift, and the strain and the temperature distribution of the optical fiber along the way can be obtained through decoupling. The minimum Pulse width of the novel prepulse (Pulse-Pre-Pump) Brillouin optical time domain analyzer PPP-BOTDA reaches 0.2ns, the spatial division rate reaches 2-10 cm, and the measurement precision reaches 7.5 mu epsilon/0.35 ℃.
2) Rayleigh (Rayleigh) scattering light-Rayleigh backward scattering light generated by residual strain generated in the drawing process of an optical fiber core, the frequency shift of the Rayleigh backward scattering light is linearly related to the temperature and the strain increment, and the basic relation is as follows
In the formula, △ vRIs the Rayleigh scattered light frequency shift, C21Is a Rayleigh strain-frequency coefficient, C22Is the rayleigh temperature-frequency coefficient.
The backward scattered light intensity of Rayleigh scattering is an information carrier of the loss along the path of the optical waveguide of the optical fiber and the attenuation of the light intensity, and the optical signal demodulator is an OTDR (optical time domain reflectometer). For POF (polymer optical fiber), the loss measurement is positively correlated to the fiber tensile strain and is sensitive. Thus, by means of OTDR detection of the attenuation along the way of the sensing fiber, the along-way distribution of the amount of tensile strain of the sensing fiber can be determined.
In summary, 1 path of sensing fiber is arranged in the measured field, and a continuous function of strain (and temperature) of the fiber along the way in one dimension can be sensed, and the longitudinal deformation can be obtained by numerical method through re-integration.
(2) The theory of mechanics is as follows:
the stress state of the impermeable geomembrane in the dam body generally belongs to bidirectional stretching. The characteristic strain, deformation modulus, etc. of the geomembrane are related to the bidirectional strain. It is therefore often necessary to monitor the bi-directional strain of the geomembrane-the down-slope strain and the cross-river strain. Therefore, two groups of orthogonal optical fiber sensing networks are adopted to perform bidirectional strain monitoring.
When the joint and the defect are repaired to break, the strain distribution at the position is distorted, the strain amount is obviously increased, and the strain amount is distributed in an ostrich shape. And (4) obtaining a fracture opening degree through numerical integration of the strain, and evaluating the development process and trend of the geomembrane fracture accident.
(II) technical scheme
(1) Optical fiber deformation monitoring system
The optical fiber deformation monitoring system mainly comprises: optical signal demodulator-transmission cable-sensing fiber, see fig. 1 (in the figure, accessories such as UPS, main control computer, optical switch, line concentrator, etc. are not shown). In the figure, 1 is an optical signal demodulator, 2 is a transmission optical cable, 3 is a combined sensing optical fiber, 4 is an SM (single mode) tight-buffered optical fiber, 5 is a carbon-coated SM optical fiber, and 6 is a fluorinated POF (polymer optical fiber).
The novel optical signal demodulator PPP-BOTDA (pre-pulse Brillouin optical time domain demodulator) has the pulse minimum width of 0.2ns, the spatial division rate of 2-10 cm, the strain precision of 7.5 mu epsilon, the strain repeatability of 5 mu epsilon, the temperature precision of 0.35℃, the measurement time of 5s and the distance range of 50 m-10 km, and is suitable for SM optical fibers.
In order to verify the performance of a PPP-BOTDA type optical fiber sensing system under the engineering field condition, a PHC pile field static load experiment and strain actual measurement are adopted in Western Ann 2011, the domestic first technical verification is carried out, and a known Swiss slide micrometer is adopted for checking. The PHC pile has the diameter of 500mm and the length of 30m, two sensing optical fibers are embedded in a pile body, a sliding micrometer is embedded in the pile body, and the static load of a test pile is 693-1464 kN. As a result, the strain measurements of the two measures substantially agree.
An important recent development in the field of fiber optics is the synthesis of BOTDA (Brillouin optical time domain analysis) and OTDR (Rayleigh optical time domain reflectometry) [ K.Kishida et al, Study of optical fiber strain-temporal sensing using hybrid Brillouin-Rayleigh system, Photonic Sensors, DOI:10.1007/s13320-013-0136-1; Sylvee Delepane-Leille et al, variation TW of COTDR method for 25km distributed optical fiber sensing, and Proc. of SPIE Vol. 8794879438-1 ]. The commercialized optical signal demodulator TW-COTDR (tunable wavelength interference optical time domain reflectometer) has excellent performance, can realize the automatic decoupling of strain-temperature measurement values, can omit strain shielding optical fibers and simplifies a sensing optical path.
In engineering application, an optical signal demodulator is matched with 1 BOTDR and 1 OTDR respectively. The former can be selected from BOTDA, PPP-BOTDA, and TW-COTDR 1 according to local conditions. The former is used when testing SM silicon core optical fiber, and the latter is used when testing POF optical fiber (details below)
(2) Large-range sensing optical fiber for geomembrane deformation
The field compatibility and the interface coupling are the key and the difficulty of the successful application of optical fiber sensing monitoring in the engineering field. The practice that optical fiber sensing is used for monitoring concrete strain and cracks provides reference for the monitoring that the optical fiber sensing is used for the geomembrane, but the geomembrane has 4-5 magnitude of difference in mechanical properties such as geometric dimension, deformation modulus, tensile strain limit and the like relative to concrete materials, and the optical fiber system and the technical scheme for monitoring the concrete strain-cracks are difficult to directly transplant to the geomembrane.
Aiming at the basic characteristic of extremely large strain range of the geomembrane, the patent provides a wide-range combined sensing optical fiber which is formed by connecting the following 3 optical fibers in parallel:
● SM Tight-buffered fiber-Strain Range 1.5%
● carbon coated SM fiber-tensile Strain Range 5%
● fluorinated POF-Latensive Strain Range 40%
The three parts are all provided with 2 (-3) cores with fibers, so that the optical fibers are convenient to lay and position, and the optical fibers are shown in the figure 1 and the figure 4.
(3) Sensing optical fiber arrangement mode for monitoring geomembrane strain and seam fracture opening
Sensing optical fibers for monitoring geomembrane strain and seam fracture opening are arranged orthogonally to the seam, as shown in figures 2-4. In fig. 2 to 3, 7 is a left geomembrane, 8 is a right geomembrane, 9 is a seam, 10 is a weld, 11 is a combined sensing optical fiber, 12 is an optical fiber fixing point (simply referred to as a node), s1Is a small distance (preferably 15-25 cm) between nodes, s2The distance between the nodes is large (40-150 cm can be selected); in FIG. 4, 13 is an optical fiber protection PE tape (10-20 cm wide), and 14 is extrusion solder bonding.
And the seam crossing sensing optical fiber orthogonal to the seam can realize the integration of geomembrane strain and seam fracture monitoring. When the seam is intact, the optical fiber measures the geomembrane longitudinal (often dam slope direction at high dam) strain. When the seam is broken, the measured value of the strain at the position is increased and obviously greater than the strains of the areas near the two sides of the seam, and the hump-shaped distribution is presented, so that the seam can be judged to be broken, and the opening degree of the seam breakage can be obtained by integrating the values of the strains between the nodes at the two sides of the seam.
For larger defect repairs, a similar monitoring arrangement is preferred, but the fiber routing should be orthogonal to the long axis of the repair scar.
(1) (4) arrangement mode of optical fiber network for deformation monitoring of geomembrane anti-seepage earth-rock dam
The geomembrane seepage prevention of a high dam is usually carried out by adopting a slope wall type, the dam slope direction strain value of the geomembrane is larger than the axial (river-crossing) strain value of the dam, so that the geomembrane is usually longitudinally unfolded along the dam slope direction, and the slope direction long seam is mainly used in all seams. For this purpose, the fiber optic network for deformation monitoring of the whole dam geomembrane impermeable system is shown in fig. 5. In the figure, 15 is a river-crossing sensing optical fiber, 16 is a dam slope sensing optical fiber, and the two form an orthogonal optical fiber network. The former monitors axial strain of a dam of the geomembrane and fracture opening of a long seam in a slope direction, and the latter monitors the strain in the slope direction of the geomembrane and the fracture opening of a transverse seam at the end of the geomembrane.
The range and distribution of the orthogonal optical fiber network are based on the principle of combining large-range coverage with key dense distribution. The distance between the dam slope direction sensing optical fibers is preferably 2.5-20.0 m, and the distance between the river crossing direction sensing optical fibers is preferably 1.0-10.0 m.
The arrangement of the sensing optical fibers is preferably consistent in density, and the key dense distribution areas (see fig. 5) are as follows:
● geomembrane tensile strain is high-the area where the risk of seam failure is high: calculating according to dam design and determining according to numerical simulation analysis results;
● geological and terrain conditions complex areas;
● dam crest area of dam with high seismic intensity: the dynamic reaction amplification effect is obvious, and the damage risk of the dam body and the geomembrane is high.
（2）
Advantageous effects
(1) The primary monitoring project of geomembrane seepage-proofing earth-rock dam deformation monitoring, namely geomembrane tensile strain monitoring, is realized, and the conventional point-type electrical measuring instrument and technology are upgraded into a distributed optical fiber sensing system and technology for online remote measurement.
(2) The difficult problem of monitoring the PE film joint fracture opening is solved, and the integration of monitoring the PE film strain-fracture opening is further formed; the provided multi-range combined sensing optical fiber can just meet the specific requirements that the tensile strain of the PE geomembrane is extremely large and the fracture opening of the joint needs to be monitored simultaneously; the method becomes a practical and advanced high-tech means with large-range coverage and multi-parameter detection, and can remarkably improve the effectiveness and the technological level of a safety monitoring system of the geomembrane anti-seepage earth-rock dam. And providing the most rapid and reliable key data for safety management decisions at key moments of strong earthquake, water leakage of a dam, flood control and emergency rescue and the like.
(3) The distributed optical fiber sensing system is corrosion-resistant, lightning-proof and anti-electromagnetic interference, has no movable parts, no abrasion and almost no zero drift, stably works for decades and has extremely small maintenance workload. The related equipment of the optical fiber sensing system has the advantages of fast price reduction, fast performance improvement and great development potential.
In short, the method has the advantages of overcoming the difficult problem of deformation monitoring of the geomembrane anti-seepage system of the current geomembrane anti-seepage earth-rock dam engineering, realizing technical upgrading and updating, and being expected to become one of the bright spots in the safety monitoring technology of the geomembrane anti-seepage earth-rock dam.
Drawings
FIG. 1 is a schematic diagram of an optical fiber deformation sensing monitoring system;
FIG. 2 is a schematic view of the arrangement of sensing optical fibers for geomembrane strain-seam fracture opening monitoring (the optical fiber covering protective tape is not shown);
FIG. 3 is a schematic longitudinal section of the sensing fiber arrangement (section of FIG. 2A-A);
FIG. 4 is a cross-sectional schematic view (section of FIG. 2B-B) of a sensing fiber arrangement;
fig. 5 is an upstream view of a fiber optic sensor network arrangement for a geomembrane impermeable system for an earth and rockfill dam.
Detailed Description
Laying of sensing optical fiber
After the welding operation of the PE geomembrane is finished, marking lines of the consolidation point positions of the sensing optical fibers on the surface of the geomembrane according to the arrangement design drawing of the optical fiber sensing network of the geomembrane anti-seepage system; properly roughening the surface of the geomembrane at each junction; the sensing fibers are unfolded and laid in place by scribing (see fig. 2-4).
Consolidation positioning process for sensing optical fiber
By means of the quantitative pulling device, the optical fiber is straightened, so that certain initial pulling strain is generated and maintained in the consolidation operation process, and the initial pulling strain of the three sensing optical fibers is preferably as follows:
● SM Tight-buffered fiber-200-600 mu epsilon
● carbon coated SM fiber-300-800 mu epsilon
● fluorinated POF fiber-1000-2000 mu epsilon
Therefore, the straightened optical fibers are detected in advance by using optical signal demodulators such as BOTDR, OTDR and the like so as to calibrate the tension value which is suitable for each sensing optical fiber and can generate the initial tension strain.
Under the condition of keeping the tensile strain, extruding a proper amount of strong quick-drying glue at each consolidation point, and consolidating and positioning the optical fiber (see fig. 2-3); at this point, the initial tensile strain must remain constant until the super glue reaches sufficient strength. This process is required to ensure that each segment of the sensing fiber between each node is kept in a straight state, and any slack or bending is avoided, thereby preventing the risk of gross errors in the initial strain field.
(III) quality inspection of sensing optical fibers, laying of PE protective tape and establishment of geomembrane strain initial field
And performing survival quality detection on each laid sensing optical fiber by using the OTDR, if an optical fiber breakpoint is found, positioning, and repairing by using an automatic welding machine. After each path of sensing optical fiber is laid, a strain initial field is established and quality inspection is finished, a PE protective belt (see figure 4) covered on the optical fiber is laid along the line in time, and two sides of the protective belt are fixed by extrusion glue. And (3) carrying out strain and temperature measurement on the laid sensing optical fiber network for a plurality of times by adopting an optical signal demodulator until a measured value meets the repeatability requirement so as to establish a strain initial field of the optical fiber network.
(IV) protection of sensing fiber
In the laying process and the subsequent building process of the geomembrane protective layer/protective slope, a specially-assigned person is necessary to watch on the site, the optical fiber is protected, all damage risks such as rolling stones, stepping on by people and the like are avoided, and the survival rate of the optical fiber is ensured.
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The innovation of the invention is funded by national science fund (project approval number: 51279119).
Claims (2)
1. A geomembrane deformation distributed optical fiber sensing monitoring system of a geomembrane anti-seepage earth-rock dam is characterized in that: 3 optical fibers with different strain test ranges are adopted, work division cooperation is carried out, so that a large-range multifunctional strain sensing and seam fracture opening monitoring integrated distributed sensing network is formed, and the time-space distribution development process of the two-way strain and seam fracture opening of the geomembrane is measured on line; the wide-range combined sensing optical fiber consists of 3 optical fibers including an SM tight-sleeved optical fiber, a carbon-coated SM optical fiber and a high-fluorine POF plastic optical fiber, wherein the SM tight-sleeved optical fiber, the carbon-coated SM optical fiber and the high-fluorine POF plastic optical fiber are all provided with 2-3 core fibers and are connected in parallel to form 1 sensing optical path; in a medium and small strain stage when the strain of the optical fiber is less than or equal to 1.5-5%, selecting and using the SM tight-sleeved optical fiber, the carbon-coated SM optical fiber and a BOTDA type high-precision Brillouin optical time domain analyzer PPP-BOTDA or a Brillouin-Rayleigh synthesis system TW-COTDR optical signal demodulator for testing; when the fiber strain is more than or equal to 5.0% in a large strain stage, performing OTDR (optical time Domain reflectometer) measurement by adopting the high-fluorine POF plastic fiber and an optical time domain reflectometer; and when the optical fiber strain measurement value of the joint section is obviously larger than the strain measurement values on the two sides of the joint section and is distributed in an ostrich-peak shape, judging that the joint at the position is broken, and determining the opening degree of the broken joint by adopting the numerical integration of the strain of the section so as to realize the real-time online diagnosis and identification of the leakage risk of the geomembrane anti-seepage system.
2. The system of claim 1, wherein the system comprises: the laying and positioning of the sensing optical fiber adopt point type consolidation; in the positioning and consolidation process, applying and stably maintaining a proper amount of initial tensile strain to the optical fibers, wherein the initial tensile strain amount of the 3 optical fibers is 200-600 mu epsilon, 300-800 mu epsilon and 1000-2000 mu epsilon in sequence; and (4) carrying out measurement on the laid optical fiber for several times in time until the repeatability precision is met, and establishing a bidirectional strain initial field of the optical fiber network.
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| CN201710205192.3A CN106931896B (en) | 2017-03-31 | 2017-03-31 | Optical fiber sensing technology and system for deformation monitoring of geomembrane anti-seepage earth-rock dam |
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| CN201710205192.3A CN106931896B (en) | 2017-03-31 | 2017-03-31 | Optical fiber sensing technology and system for deformation monitoring of geomembrane anti-seepage earth-rock dam |
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| CN106931896B true CN106931896B (en) | 2020-04-17 |
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| CN108571945B (en) * | 2018-06-19 | 2023-06-16 | 山东省水利科学研究院 | Method for monitoring underwater geomembrane by using node array |
| CN108844515B (en) * | 2018-06-19 | 2023-06-16 | 山东省水利科学研究院 | Monitoring method and system for underwater geomembrane |
| CN108547261B (en) * | 2018-06-19 | 2023-11-24 | 山东省水利科学研究院 | Monitoring method of underwater geomembrane monitoring system adopting sector monitoring disc |
| CN108759769B (en) * | 2018-06-19 | 2023-06-16 | 山东省水利科学研究院 | Underwater geomembrane monitoring method adopting pentagonal monitoring disc |
| CN109357168A (en) * | 2018-11-19 | 2019-02-19 | 大连青松智慧生态科技有限公司 | A kind of pipeline leakage checking system and construction method based on distribution type fiber-optic |
| CN110596182A (en) * | 2019-09-29 | 2019-12-20 | 西安理工大学 | Geomembrane damage leakage amount monitoring system and method based on distributed optical fibers |
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