Anchor cable whole-section stress monitoring device based on distributed optical fibers and calibration method

Abstract

The embodiment of the invention discloses an anchor cable whole-section stress monitoring device based on distributed optical fibers and a calibration method. The anchor cable full-section stress monitoring device based on the distributed optical fibers comprises a steel strand and an optical fiber sensor, the optical fiber sensor is embedded in a middle wire of the steel strand, and measuring points are arranged in the length direction of the middle wire of the steel strand. The calibration method applying the distributed optical fiber-based anchor cable whole-section stress monitoring device comprises the following steps of: adjusting tensioning equipment, and installing a to-be-calibrated anchor cable; checking the state of the equipment; installing an optical fiber sensor at the calibration part of the to-be-calibrated anchor cable, carrying out a limit pull-out test and recording mechanical data, carrying out a tension calibration test and recording optical data; according to the mechanical parameters and the optical data, the sensitivity parameters of the anchor cable to be calibrated are calibrated. According to the invention, the length of the whole anchor cable can be continuously monitored, the limitation of a traditional method is overcome, and the monitoring accuracy and globality are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber monitoring, and in particular to a distributed optical fiber-based full-section anchor cable stress monitoring device and a calibration method. Background Art

[0002] Anchor cable is an important engineering element used to support structures or soil. It bears tension to provide stability. Monitoring the stress state of anchor cables is crucial to the safety and reliability of structures, especially under long-term use and changing environmental conditions. Traditional anchor cable stress monitoring methods usually use sensors such as resistance strain gauges, which need to be arranged on the surface or inside the anchor cable.

[0003] Fiber optic sensing technology is an advanced technology that uses optical principles for sensing. It has been widely used in structural monitoring, temperature measurement, strain monitoring and other fields. Optical fiber is a periodic refractive index modulation structure. By introducing this structure into the anchor cable, a sensor that can sensitively respond to external influences is formed. When the light wave propagates to the optical fiber structure, the frequency will be reflected. When the deformation of the steel strand changes, the reflected frequency will also change accordingly. Through the principle of light reflection, when the optical fiber is subjected to external stress (such as the stretching of the anchor cable) or temperature changes, the periodic structure of the optical fiber changes, resulting in a shift in the center frequency. The amount of this spectral frequency shift can be measured, thereby realizing the monitoring of the stress state of the anchor cable.

[0004] Traditional monitoring methods require sensors to be installed on the surface or inside of the anchor cable, which involves a construction process and requires professional technicians to operate. The installation process is cumbersome and the deployment method requires frequent maintenance, especially in complex engineering structures or underground environments, which increases the maintenance cost and difficulty of the monitoring system. Moreover, traditional sensors usually monitor at specific locations, making it difficult to achieve full-segment, continuous stress monitoring. Summary of the invention

[0005] In view of this, the purpose of the embodiments of the present invention is to provide a distributed optical fiber anchor cable full-segment stress monitoring device and calibration method, so that the entire length of the anchor cable can be continuously monitored, overcoming the limitations of traditional methods and improving the accuracy and globality of monitoring.

[0006] In a first aspect, an embodiment of the present invention provides a distributed optical fiber-based full-section anchor cable stress monitoring device, which includes a steel strand and an optical fiber;

[0007] The steel strand comprises a center wire and side wires, and the center wire and the side wires are twisted into shape.

[0008] The optical fiber is embedded in the middle filament and arranged along the length direction of the middle filament.

[0009] The modulation of the periodic refractive index causes light to reflect when passing through the optical fiber. The periodic structure in the optical fiber causes light of different wavelengths to interact with the optical fiber in different ways, thus forming a reflection peak at the center frequency. By changing the force characteristics of the anchor cable, the center frequency of the optical fiber can be adjusted. For example, when the strain or temperature changes, the center frequency of the distributed optical fiber will change, resulting in a spectral shift, allowing the optical fiber sensor to be used for sensing.

[0010] In combination with the first aspect, the embodiment of the present invention provides a first possible implementation of the first aspect, wherein the diameter of the wire in the steel strand is 5.2 mm.

[0011] In combination with the first aspect, the embodiment of the present invention provides a second possible implementation of the first aspect, wherein the diameter of the edge wire of the embedded distributed optical fiber steel strand is 5 mm.

[0012] In combination with the first aspect, the embodiment of the present invention provides a third possible implementation of the first aspect, wherein a groove is engraved along the axial direction at the wire position of the steel strand;

[0013] The optical fiber sensor is adhered in the groove by adhesive;

[0014] The middle wire of the steel strand is attached to the optical fiber sensor and then twisted with the side wire to form a shape;

[0015] The optical fiber sensor is extended from the end of the wire in the steel strand and then packaged.

[0016] The above-mentioned technology of embedding continuous distributed optical fiber into the anchor material - the central wire of the steel strand not only improves the strength and surface friction resistance, which can facilitate groove carving and implantation, but also greatly reduces the overall stiffness, has good coupling with loose bodies, and can be directly buried in the soil to monitor soil strain.

[0017] In a second aspect, an embodiment of the present invention further provides a calibration method for a full-section anchor cable stress monitoring device based on a distributed optical fiber, which includes:

[0018] Adjust the tensioning equipment and install the anchor cable to be calibrated;

[0019] Perform equipment status checks;

[0020] Installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing an extreme pull-out test and recording mechanical data;

[0021] Restore the tensioning equipment and the anchor cable to be calibrated, install an optical fiber sensor at the calibration position of the anchor cable to be calibrated, perform a tensioning calibration test and record optical data;

[0022] Calibrate the sensitivity parameters of the anchor cable to be calibrated according to the mechanical parameters and the optical data;

[0023] The device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber is the device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber as described above.

[0024] The technical effect is that the calibration method of the distributed optical fiber-based full-section anchor cable stress monitoring device provided by the present invention has the advantages of high precision, comprehensive understanding of anchor cable performance, strong adaptability and real-time monitoring, ensuring the stability and reliability of the monitoring system.

[0025] In combination with the second aspect, an embodiment of the present invention provides a first possible implementation of the second aspect, wherein the adjusting the tensioning equipment and installing the anchor cable to be calibrated includes:

[0026] Adjust the base length of the tensioning equipment to meet the length range of the anchor cable to be calibrated;

[0027] The anchor cable to be calibrated is installed on the tensioning device, and the end of the optical fiber sensor is connected to a demodulator.

[0028] Its technical effects are: adaptability, simplified operation, ensuring stable installation and optical connection guarantee.

[0029] In combination with the second aspect, an embodiment of the present invention provides a second possible implementation of the second aspect, wherein the performing device status check includes:

[0030] Applying a prestress of 10% P in the anchor cable to be calibrated by the tensioning device, wherein P is the prestress of the anchor cable to be calibrated;

[0031] Check the working status of the equipment and unload the prestress if it meets the requirements.

[0032] The technical effect is as follows: by checking the working status of the equipment and unloading the prestress after meeting the requirements, the risk of equipment failure can be effectively reduced; applying a prestress of 10% P corresponds to a prestress value of 26kN, which provides a reference standard for subsequent tests. As a benchmark value for the test, it helps in subsequent data analysis and result interpretation, realizes effective monitoring of the working status of the equipment, reduces the risk of equipment failure, improves the stability and reliability of the calibration process, and ensures the smooth progress of subsequent tests.

[0033] In combination with the second aspect, an embodiment of the present invention provides a third possible implementation of the second aspect, wherein the step of installing an optical fiber sensor at a calibration position of the anchor cable to be calibrated, performing an extreme pull-out test and recording mechanical data comprises:

[0034] Marking a designated position on the anchor cable to be calibrated, and installing a fiber optic sensor;

[0035] Applying a loading force to the position of each optical fiber sensor, gradually increasing the loading force until the anchor cable to be calibrated breaks;

[0036] After the fracture, stand still and observe for 5 minutes, and record the maximum force value F of the anchor cable to be calibrated after the wavelength and / or frequency stabilizes.

[0037] Its technical effect is: through local extreme pull-out testing, real-time monitoring and recording of multi-point data, as well as static observation and other steps, the detail and accuracy of the extreme pull-out test are improved, providing important data support for subsequent sensitivity parameter calibration.

[0038] In combination with the second aspect, an embodiment of the present invention provides a fourth possible implementation of the second aspect, wherein the step of installing an optical fiber sensor at a calibration position of the anchor cable to be calibrated, performing a tension calibration test and recording optical data comprises:

[0039] Tensioning is performed step by step at the position of each optical fiber sensor, with a total of 7 levels of loading, loading step by step within the load range of 50 kN to 190 kN, and maintaining the loading speed at 2 mm / min;

[0040] After each tensioning stage, hold the load and observe for 5 minutes. After the wavelength and / or frequency are stable, record the corresponding wavelength change value Δλ=λ i -λ0, where λ i is the center frequency of the optical fiber sensor under the current tension, and λ0 is the center frequency of the optical fiber sensor under the initial prestress.

[0041] The technical effect is to record the spectral shift change value of each optical fiber sensor under different tension loads, take into account the central wavelength under the current tension force and initial prestress, and provide the optical response data of the anchor cable under different stress states.

[0042] In combination with the second aspect, an embodiment of the present invention provides a fifth possible implementation of the second aspect, wherein calibrating the sensitivity parameter of the anchor cable to be calibrated according to the mechanical parameter and the optical data includes:

[0043] Calculate the perceived strain value ε of the optical fiber sensor g =Δl / l0, where Δl is the change in length, l 0为 The length of the anchor cable to be tensioned and broken in the initial state;

[0044] The sensitivity parameter K of the anchor cable to be calibrated is calculated ε =Δλ / ε g .

[0045] Its technical effect is: by calculating the perceived strain value, using the nominal area and elastic modulus, accurate sensitivity parameters are obtained, providing key parameter references for anchor stress monitoring.

[0046] The beneficial effects of the embodiments of the present invention are:

[0047] The present invention provides a calibration method for a full-section anchor cable stress monitoring device based on distributed optical fiber. By adjusting the tensioning equipment, checking the equipment status, performing an ultimate pull-out test, and performing a tensioning calibration test, the sensitivity parameters of the anchor cable to be calibrated are fully calibrated, thereby ensuring the accuracy and reliability of the monitoring system. During the calibration process, the stable optical data of the anchor cable under different loads are obtained by observing the step-by-step loading and load holding, and recording the wavelength change value after each stage of tensioning, thereby improving the authenticity of the test and the reliability of the data. Based on the mechanical parameters and optical data, the perceived strain value of the optical fiber sensor is calculated, and the sensitivity parameters of the anchor cable to be calibrated are obtained through the nominal area and elastic modulus, thereby providing key data support for subsequent anchor cable stress monitoring and ensuring the accuracy of the monitoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 A flow chart of a calibration method for a distributed optical fiber-based anchor cable full-section stress monitoring device according to the present invention;

[0050] Figure 2a It is a structural schematic diagram of the whole-section stress monitoring device of the anchor cable based on distributed optical fiber of the present invention;

[0051] Figure 2b It is a side view structural schematic diagram of the entire anchor cable stress monitoring device based on distributed optical fiber according to the present invention;

[0052] Figure 2c It is a schematic diagram of the cross-sectional structure of the steel strand in the whole-section stress monitoring device of the anchor cable based on distributed optical fiber of the present invention;

[0053] Figure 3a This is the first experimental spectrum offset result of optical fiber No. 1 in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0054] Figure 3b The calibration relationship between the first strain of optical fiber No. 1 and the spectral offset in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0055] Figure 3c This is the result of the second experimental spectrum shift of optical fiber No. 1 in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0056] Figure 3d The calibration relationship between the second strain of optical fiber No. 1 and the spectral offset in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0057] Figure 4a This is the first experimental spectrum offset result of optical fiber No. 2 in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0058] Figure 4b The calibration relationship between the first strain and the spectral offset of the second optical fiber in the strain calibration test of the embedded distributed optical fiber steel strand of the present invention;

[0059] Figure 4c This is the result of the second experimental spectrum shift of the No. 2 optical fiber in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0060] Figure 4d The calibration relationship between the second strain of optical fiber No. 2 and the spectral offset in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0061] Figure 5a This is the first experimental spectrum offset result of the No. 3 optical fiber in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0062] Figure 5b The calibration relationship between the first strain and the spectral offset of the third optical fiber in the strain calibration test of the embedded distributed optical fiber steel strand of the present invention;

[0063] Figure 5c This is the result of the second experiment spectrum shift of the third optical fiber in the strain calibration test of embedded distributed optical fiber steel strand of the present invention;

[0064] Figure 5d This is the calibration relationship between the second strain of the third optical fiber and the spectral offset in the strain calibration test of the embedded distributed optical fiber steel strand of the present invention.

[0065] In the figure: 1-middle wire; 2-side wire of steel strand; 3-embedded distributed optical fiber steel strand; 4-groove. DETAILED DESCRIPTION

[0066] 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. Generally, 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.

[0067] Please refer to Figure 1 The first embodiment of the present invention provides a distributed optical fiber-based full-section anchor cable stress monitoring device, wherein:

[0068] Steel strands and optical fibers;

[0069] The steel strand comprises a middle wire and a side wire, and the middle wire and the side wire are twisted into shape;

[0070] The optical fiber is embedded in the middle filament and arranged along the length direction of the middle filament.

[0071] The specific operation is as follows: ① Break up the side wires of the steel strand and take out the center wire; ② Use mechanical means to carve an axial groove on the center wire; ③ Use adhesive to stick the optical fiber into the groove; ④ Twist the packaged center wire and side wires back into shape; ⑤ Lead out the optical fiber at the end of the steel strand and package it for protection. The optical fiber along the length of the center wire can be used as a stress monitoring point for the entire section.

[0072] Specifically, the modulation of the periodic refractive index causes light to reflect when passing through the measuring point, and the periodic structure in the optical fiber causes the light to interact with the measuring point in different ways, thus forming Rayleigh reflection. By changing the force characteristics of the steel strand, the center frequency can be adjusted. When the optical fiber is affected by external factors, such as strain or temperature changes, the optical fiber frequency will change, causing the spectrum to shift, allowing the optical fiber sensor to be used for sensing.

[0073] Wherein, the diameter of the wire in the steel strand is 5.2 mm.

[0074] Wherein, the diameter of the edge wire of the embedded distributed optical fiber steel strand is 5 mm.

[0075] Wherein, the steel strand is grooved along the axial direction along the position of the center wire;

[0076] The optical fiber sensor is adhered in the groove by adhesive;

[0077] The middle wire of the steel strand is attached to the optical fiber sensor and then twisted with the side wire to form a shape;

[0078] The optical fiber sensor is extended from the end of the wire in the steel strand and then packaged.

[0079] The side wires of the steel strand are scattered, and the center wire is taken out to obtain a core-less steel strand.

[0080] The above-mentioned technology of embedding continuous distributed optical fiber into the anchor material - the central wire of the steel strand not only improves the strength and surface friction resistance, which can facilitate groove carving and implantation, but also greatly reduces the overall stiffness, has good coupling with loose bodies, and can be directly buried in the soil to monitor soil strain.

[0081] Referring to FIG. 2 , a second embodiment of the present invention provides a calibration method for a distributed optical fiber-based anchor cable full-section stress monitoring device, which includes:

[0082] Adjust the tensioning equipment and install the anchor cable to be calibrated;

[0083] Perform equipment status checks;

[0084] Installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing an extreme pull-out test and recording mechanical data;

[0085] Restore the tensioning equipment and the anchor cable to be calibrated, install an optical fiber sensor at the calibration position of the anchor cable to be calibrated, perform a tensioning calibration test and record optical data;

[0086] Calibrate the sensitivity parameters of the anchor cable to be calibrated according to the mechanical parameters and the optical data;

[0087] The device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber is the device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber as described above.

[0088] The technical effect is that the calibration method of the distributed optical fiber-based full-section anchor cable stress monitoring device provided by the present invention has the advantages of high precision, comprehensive understanding of anchor cable performance, strong adaptability and real-time monitoring, ensuring the stability and reliability of the monitoring system.

[0089] Wherein, the adjusting of the tensioning equipment and the installation of the anchor cable to be calibrated include:

[0090] Adjust the base length of the tensioning equipment to meet the length range of the anchor cable to be calibrated;

[0091] The anchor cable to be calibrated is installed on the tensioning device, and the end of the optical fiber sensor is connected to a demodulator.

[0092] Its technical effects are: adaptability, simplified operation, ensuring stable installation and optical connection guarantee.

[0093] The device status check includes:

[0094] Applying a prestress of 10% P in the anchor cable to be calibrated by the tensioning device, wherein P is the prestress of the anchor cable to be calibrated;

[0095] Check the working status of the equipment and unload the prestress if it meets the requirements.

[0096] Among them, the prestress of 10%P corresponds to a prestress value of 26kN.

[0097] The technical effect is as follows: by checking the working status of the equipment and unloading the prestress after meeting the requirements, the risk of equipment failure can be effectively reduced; applying a prestress of 10% P corresponds to a prestress value of 26kN, which provides a reference standard for subsequent tests. As a benchmark value for the test, it helps in subsequent data analysis and result interpretation, realizes effective monitoring of the working status of the equipment, reduces the risk of equipment failure, improves the stability and reliability of the calibration process, and ensures the smooth progress of subsequent tests.

[0098] The step of installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing an extreme pull-out test and recording mechanical data comprises:

[0099] Marking a designated position on the anchor cable to be calibrated, and installing a fiber optic sensor;

[0100] Applying a loading force to the position of each optical fiber sensor, gradually increasing the loading force until the anchor cable to be calibrated breaks;

[0101] After the fracture, stand still and observe for 5 minutes, and record the maximum force value F of the anchor cable to be calibrated after the wavelength and / or frequency stabilizes.

[0102] Its technical effect is: through local extreme pull-out testing, real-time monitoring and recording of multi-point data, as well as static observation and other steps, the detail and accuracy of the extreme pull-out test are improved, providing important data support for subsequent sensitivity parameter calibration.

[0103] Wherein, the step of installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing a tension calibration test and recording optical data comprises:

[0104] Tensioning is performed step by step at the position of each optical fiber sensor, with a total of 7 levels of loading, loading step by step within the load range of 50 kN to 190 kN, and maintaining the loading speed at 2 mm / min;

[0105] After each tensioning stage, hold the load and observe for 5 minutes. After the wavelength and / or frequency are stable, record the corresponding wavelength change value Δλ=λ i -λ0, where λ i is the center frequency of the optical fiber sensor under the current tension, and λ0 is the center frequency of the optical fiber sensor under the initial prestress.

[0106] The technical effect is to record the wavelength change value of each optical fiber sensor under different tension loads, take into account the central frequency under the current tension force and initial prestress, and provide the optical response data of the anchor cable under different stress states.

[0107] Wherein, calibrating the sensitivity parameter of the anchor cable to be calibrated according to the mechanical parameter and the optical data comprises:

[0108] Calculate the perceived strain value ε of the optical fiber sensor g =Δl / l0, where Δl is the change in length, l 0为 The length of the anchor cable to be tensioned and broken in the initial state. The sensitivity parameter K of the anchor cable to be calibrated is calculated ε =Δλ / ε g .

[0109] Its technical effect is: by calculating the perceived strain value, using the nominal area and elastic modulus, accurate sensitivity parameters are obtained, providing key parameter references for anchor stress monitoring.

[0110] The second embodiment of the present invention provides an extreme pull-out of a full-section anchor cable stress monitoring device based on distributed optical fiber, wherein the test results are shown in Table 1, and the results show that the mechanical properties of the steel strand embedded with optical fiber meet the technical requirements of "Steel Strand for Prestressed Concrete" GB / T5224-2014.

[0111] Specifically, the steel strand used is 1x7 standard type, which is twisted with 1 center wire with a diameter of 5.2mm and 6 side wires with a diameter of 5mm. The nominal diameter is 15.20mm. According to the prestressed concrete steel strand (GBT5224-2014), the cross-sectional area is 140mm 2 , the tensile strength is 1860MPa, the minimum yield load is 229KN, and the minimum ultimate bearing capacity is 260KN.

[0112] Table 1: Performance test results of cored steel strands with embedded optical fiber

[0113]

[0114] The strain test results of No. 1 embedded distributed optical fiber steel strand during the tensile process are as follows: Figure 3a to Figure 3dAs shown in the figure, as the tensile load level increases, the spectral frequency decreases, and the effective tensile section in the tested section is relatively flat, which is consistent with the actual stress condition of the optical fiber. The strain sensitivity test results of the two tests are shown in Table 2. The strain sensitivities are 0.1542 GHz / με and 0.1519 GHz / με respectively, the average strain sensitivity is 0.1531 GHz / με, and the linearity is above 0.999.

[0115] Table 2 Strain calibration test results of steel strands embedded with distributed optical fiber 1

[0116] test Gauge factor (GHZ / με) Linearity first 0.1542 0.9999 Second time 0.1519 0.9997

[0117] The strain test results of No. 2 embedded distributed optical fiber steel strand during the tensile process are as follows: Figures 4a to 4d As shown in the figure, with the increase of tensile load level, the spectral frequency decreases, and the effective tensile section in the tested section is relatively flat, which is consistent with the actual stress condition of the optical fiber. The strain sensitivity test results of the two tests are shown in Table 3. The strain sensitivities are 0.1509 GHz / με and 0.1516 GHz / με respectively, the average strain sensitivity is 0.1513 GHz / με, and the linearity is above 0.999.

[0118] Table 3 Strain calibration test results of steel strands embedded with distributed optical fiber 2

[0119] test Gauge factor (GHZ / με) Linearity first 0.1509 0.9998 Second time 0.1516 0.9997

[0120] The strain test results of No. 3 embedded distributed optical fiber steel strand during the tensile process are as follows: Figure 5a to Figure 5d As shown in the figure, with the increase of tensile load level, the spectral frequency decreases, and the effective tensile section in the tested section is relatively flat, which is consistent with the actual stress condition of the optical fiber. The strain sensitivity test results of the two tests are shown in Table 4. The strain sensitivities are 0.1471GHz / με and 0.1525GHz / με respectively, and the average strain sensitivity is 0.1498GHz / με. The linearity is above 0.999.

[0121] Table 4 Strain calibration test results of steel strands embedded with distributed optical fiber 3

[0122] test Gauge coefficient (GHZ / με) Linearity first 0.1471 0.9996 Second time 0.1525 0.9999

[0123] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A distributed optical fiber-based anchor cable full-section stress monitoring device, characterized in that: Including steel strands and optical fibers; The steel strand comprises a middle wire and a side wire, and the middle wire and the side wire are twisted into shape; The optical fiber is embedded in the middle filament and arranged along the length direction of the middle filament.

2. The distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 1 is characterized in that: The diameter of the wire embedded in the distributed optical fiber steel strand is 5.2 mm.

3. The distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 1 is characterized in that: The diameter of the edge wire of the embedded distributed optical fiber steel strand is 5mm.

4. The distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 1 is characterized in that: The middle thread is engraved with grooves along the axial direction; The optical fiber is adhered in the groove by adhesive; The middle wire is bonded to the optical fiber and then twisted with the side wire to form a shape; The end of the middle wire of the optical fiber is extended and then packaged.

5. A calibration method for a full-section anchor cable stress monitoring device based on distributed optical fiber, characterized in that: include: Adjust the tensioning equipment and install the anchor cable to be calibrated; Perform equipment status checks; Installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing an extreme pull-out test and recording mechanical data; Restore the tensioning equipment and the anchor cable to be calibrated, install an optical fiber sensor at the calibration position of the anchor cable to be calibrated, perform a tensioning calibration test and record optical data; Calibrate the sensitivity parameters of the anchor cable to be calibrated according to the mechanical parameters and the optical data; The device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber is the device for monitoring the stress of the entire section of an anchor cable based on distributed optical fiber as described in any one of claims 1 to 4.

6. The calibration method of the distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 5 is characterized in that: The adjusting of the tensioning equipment and the installation of the anchor cable to be calibrated include: Adjust the base length of the tensioning equipment to meet the length range of the anchor cable to be calibrated; The anchor cable to be calibrated is installed on the tensioning device, and the end of the optical fiber sensor is connected to a demodulator.

7. The calibration method of the distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 6 is characterized in that: The device status check includes: Applying a prestress of 10% P in the anchor cable to be calibrated by the tensioning device, wherein P is the prestress of the anchor cable to be calibrated; Check the working status of the equipment and unload the prestress if it meets the requirements.

8. The calibration method of the anchor cable full-section stress monitoring device based on distributed optical fiber according to claim 7 is characterized in that: The step of installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing an ultimate pull-out test and recording mechanical data comprises: Marking a designated position on the anchor cable to be calibrated, and installing a fiber optic sensor; Applying a loading force to the position of each optical fiber sensor, gradually increasing the loading force until the anchor cable to be calibrated breaks; After the fracture, stand still and observe for 5 minutes, and record the maximum force value F of the anchor cable to be calibrated after the wavelength and / or frequency stabilizes.

9. The calibration method of the distributed optical fiber-based anchor cable full-section stress monitoring device according to claim 8 is characterized in that: The step of installing an optical fiber sensor at the calibration position of the anchor cable to be calibrated, performing a tension calibration test and recording optical data comprises: Tensioning is performed step by step at the position of each optical fiber sensor, with a total of 7 levels of loading, loading step by step within the load range of 50 kN to 190 kN, and maintaining the loading speed at 2 mm / min; After each tensioning, hold the load for 5 minutes and record the corresponding wavelength change value Δλ=λ after the frequency stabilizes. i -λ0, where λ i is the center frequency of the optical fiber sensor under the current tension, and λ0 is the center frequency of the optical fiber sensor under the initial prestress.

10. The calibration method of the anchor cable full-section stress monitoring device based on distributed optical fiber according to claim 9, characterized in that: The step of calibrating the sensitivity parameter of the anchor cable to be calibrated according to the mechanical parameter and the optical data comprises: Calculate the perceived strain value ε of the optical fiber sensor g =Δl / l0, where Δl is the change in length, l 0为 The length of the anchor cable to be tensioned and broken in the initial state; The sensitivity parameter K of the anchor cable to be calibrated is calculated ε =Δλ / ε g .

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