CN112923864B - Calculation method for distributed optical fiber-protective layer-adhesive layer-substrate strain transfer - Google Patents
Calculation method for distributed optical fiber-protective layer-adhesive layer-substrate strain transfer Download PDFInfo
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- 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
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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
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35383—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques
Abstract
A calculation method of distributed optical fiber-protective layer-adhesive layer-matrix strain transfer belongs to the field of civil engineering structure operation safety intelligent monitoring. Constructing a shearing relation model of the core optical fiber and the composite protective layer according to the adopted cross-sectional parameters of the distributed sensing optical cable, and further calculating the strain transfer rate of the core optical fiber and the composite protective layer; calculating the strain transfer rate of the composite protective layer, the adhesive layer and the matrix based on a shear lag theory according to the field layout condition of the distributed sensing optical cable; establishing an optical fiber-composite protective layer-adhesive layer-matrix numerical model of distributed optical fiber sensing to obtain the corrected strain transmissibility of the optical fiber-composite protective layer-adhesive layer-matrix; and (4) summarizing and analyzing the statistical characteristics of the parameter indexes of the optical cable adhesive layer to obtain an optical fiber-composite protective layer-adhesive layer-matrix strain transmission result considering the influence of optical cable construction and installation factors. The invention solves the problem of accurate mapping of the test value of the sensing optical cable and the actual strain of the matrix structure connected with the optical cable.
Description
Technical Field
The invention belongs to the field of intelligent monitoring of civil engineering structure operation safety, and particularly relates to a calculation method of distributed optical fiber-protective layer-adhesive layer-matrix strain transfer.
Background
The large civil structure has long service life and the working capacity of the large civil structure is declined under the inevitable influence of factors such as environmental corrosion, material aging, long-term effect of load and the like in the service period of the large civil structure. Once these structures lose their capacity to operate, they are subject to considerable losses, which are subsequently unthinkable, and it is therefore of great importance to monitor the civil engineering structure for a long period of service, diagnose and detect problems in time, and eliminate potential risks. Since civil engineering structures tend to be large in size and numerous in degree of freedom, an effective sensing technology is urgently required. The optical fiber has the characteristics of simultaneous sensing and information transmission, low long-distance transmission loss, no influence of electromagnetic interference, portability, easy system integration and the like, is very suitable to be used as a sensing medium, particularly a distributed optical fiber sensing technology, and can realize continuous measurement in space.
By utilizing the characteristics of long monitoring distance, high measuring point resolution and the like of the high-performance distributed optical fiber sensing technology, the full-time perception of the whole area of the large civil engineering structure can be realized, the early warning of the existing potential structure risk can be carried out in time, and the data support is provided for the maintenance and reinforcement of the civil engineering structure. However, in the process of applying the distributed optical fiber sensing technology to the operation safety monitoring of the actual civil engineering structure, in order to protect the sensing optical fiber from being damaged by the changes of installation and construction conditions and service environment, the surface of the optical fiber needs to be wrapped with a composite protective layer with a certain thickness, so that the sensing optical cable is formed; meanwhile, the connection condition and the installation construction method of the sensing optical cable and the civil structure are different due to different specific projects, so that the test strain value of the sensing optical fiber is not a real reflection of the actual strain of the base structure connected with the optical cable. Aiming at the problem, the invention provides a calculation method of distributed optical fiber-protective layer-adhesive layer-matrix strain transfer, which aims to solve the problem of accurate mapping of a distributed sensing optical cable test value and the actual strain of a matrix structure connected with an optical cable.
Disclosure of Invention
The invention aims to provide a calculation method for distributed optical fiber-protective layer-adhesive layer-matrix strain transmission, which aims to accurately obtain an accurate mapping relation between a distributed sensing optical cable strain test value and actual strain of a matrix structure connected with an optical cable.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a calculation method for distributed optical fiber-protective layer-adhesive layer-matrix strain transfer comprises the following steps:
the method comprises the following steps: determining the rigidity index of the optical fiber composite protective layer according to the adopted cross-section parameters of the distributed sensing optical cable, constructing a shearing relation model of the core optical fiber and the composite protective layer, and calculating the strain transfer rate of the core optical fiber-the composite protective layer;
step two: determining the thickness and shear modulus of the pasting layer of the distributed sensing optical cable according to the field laying condition of the distributed sensing optical cable, and calculating the strain transfer rate of the composite protective layer, the pasting layer and the matrix based on the shear hysteresis theory;
step three: establishing an optical fiber-composite protective layer-adhesive layer-matrix numerical model of distributed optical fiber sensing according to field layout conditions, and correcting and calculating shear hysteresis parameters of the strain transmissibility in the first step and the second step according to a minimum error principle to obtain a result after the strain transmissibility correction of the optical fiber-composite protective layer-adhesive layer-matrix;
step four: and after the on-site installation of the distributed sensing optical cable is finished, testing to obtain the thickness, width and length indexes of the optical cable bonding layer, summarizing and analyzing the statistical characteristics of the parameter indexes of the optical cable bonding layer, substituting the statistical characteristics into the step three, and calculating the optical fiber-composite protective layer-bonding layer-matrix strain transmission result considering the influence of optical cable construction installation factors.
Compared with the prior art, the invention has the beneficial effects that:
the invention relates to a distributed optical fiber sensing optical fiber-composite protective layer-adhesive layer-matrix strain transfer calculation method, which comprises the steps of firstly, constructing a shearing relation model of a core optical fiber and a composite protective layer according to adopted distributed sensing optical cable section parameters, and further calculating the strain transfer rate of the core optical fiber-composite protective layer; secondly, calculating the strain transfer rate of the composite protective layer, the adhesive layer and the substrate based on the shear hysteresis theory; on the basis, establishing an optical fiber-composite protective layer-adhesive layer-matrix numerical model of distributed optical fiber sensing to obtain the corrected strain transmissibility of the optical fiber-composite protective layer-adhesive layer-matrix; and finally, after the field installation of the distributed sensing optical cable is finished, summarizing and analyzing the statistical characteristics of the parameter indexes of the optical cable adhesive layer to obtain an optical fiber-composite protective layer-adhesive layer-matrix strain transmission result considering the influence of optical cable construction installation factors. Compared with the prior art, the problem of accurate mapping of the test value of the distributed sensing optical cable and the actual strain of the matrix structure connected with the optical cable is solved.
Drawings
Fig. 1 is a flow chart of a calculation method of distributed optical fiber-protective layer-adhesive layer-matrix strain transfer according to the present invention.
Fig. 2 is a photograph of a strain sensing cable in an example of implementation.
FIG. 3 is a finite element model of an optical fiber-composite protective layer-adhesive layer-matrix in an embodiment example.
FIG. 4 is a graph showing the calculation results of the strain transmittance before correction under the 20cm pasting condition in the working example.
FIG. 5 is a graph showing the calculation results of the strain transmittance before correction under the 30cm pasting condition in the practical example.
FIG. 6 is a graph showing the calculation results of the strain transmittance before correction under the 40cm pasting condition in the practical example.
FIG. 7 is a graph showing the calculation results of the strain transmittance after correction under the 20cm pasting condition in the examples.
FIG. 8 is a graph showing the calculation results of the strain transmittance after correction under the 30cm pasting condition in the practical example.
FIG. 9 is a graph showing the calculation results of the corrected strain transmittance under the 40cm pasting condition in the practical example.
Detailed Description
The first embodiment is as follows: as shown in fig. 1, the present embodiment discloses a method for calculating strain transmission of distributed optical fiber-protective layer-adhesive layer-substrate, the method comprising the following steps:
the method comprises the following steps: determining the rigidity index of the optical fiber composite protective layer according to the adopted cross-section parameters of the distributed sensing optical cable, constructing a shearing relation model of the core optical fiber and the composite protective layer, and calculating the strain transfer rate of the core optical fiber-the composite protective layer;
step two: determining the thickness and shear modulus of the pasting layer of the distributed sensing optical cable according to the field laying condition of the distributed sensing optical cable, and calculating the strain transfer rate of the composite protective layer, the pasting layer and the matrix based on the shear hysteresis theory;
step three: establishing an optical fiber-composite protective layer-adhesive layer-matrix numerical model of distributed optical fiber sensing according to field layout conditions, and correcting and calculating shear hysteresis parameters of the strain transmissibility in the first step and the second step according to a minimum error principle to obtain a result after the strain transmissibility correction of the optical fiber-composite protective layer-adhesive layer-matrix;
step four: and after the on-site installation of the distributed sensing optical cable is finished, testing to obtain the thickness, width and length indexes of the optical cable bonding layer, summarizing and analyzing the statistical characteristics of the parameter indexes of the optical cable bonding layer, substituting the statistical characteristics into the step three, and calculating the optical fiber-composite protective layer-bonding layer-matrix strain transmission result considering the influence of optical cable construction installation factors.
The second embodiment is as follows: in this embodiment, the first embodiment is further described, and the method for calculating the strain transmittance of the core optical fiber-composite protective layer in the first step includes:
the method comprises the following steps: dividing a composite protective layer into an inner protective layer, a rigid layer and an outer protective layer by taking a rigid layer (namely steel stranded wires) in the composite protective layer as a boundary, determining the section size and material parameters of each layer in a layering manner, constructing a shearing relation model of a core optical fiber and the composite protective layer as shown in a formula (1),
in the formula, rfIs the radial distance, r, from the core fiber axis to the core fiber-inner protective layer interfaceiIs the radial distance, τ, from the core fiber axis to the inner protective layer-rigid layer interfacefIs the shear stress, epsilon, at the core fiber-inner protective layer interfacefIs positively strained in the core fiber, taui,rShear stress at a certain interface in the inner protective layer at a distance r from the axis of the optical fiber, Ef、EiRespectively, the elastic modulus of the core fiber and the inner protective layer, dx is the fiber micro-segment length, GiIs the shear modulus of the inner protective layer, uf、usAxial deformation of the core optical fiber and the rigid layer respectively;
the first step is: calculating the strain transmissibility alpha of the core optical fiber and the composite protective layer by the formula (2) by using a shearing relation model of the core optical fiber and the composite protective layer1，
Wherein L is the sticking length of the sensing optical cable, epsilonsIs positively strained by the rigid layer, alpha1Denotes the strain transfer rate, k, from the paste end point x1Denotes alpha1Shear lag parameters in the calculation process are represented by cosh (·) which is a hyperbolic cosine function.
The third concrete implementation mode: in this embodiment, the first embodiment is further explained, and the method for calculating the strain transfer rate of the composite protective layer, the adhesive layer and the substrate in the second step includes:
step two, firstly: determining the size and material properties of the adhesive layer of the sensing optical cable, constructing a composite protective layer-adhesive layer-matrix strain transfer model based on a shear hysteresis theory according to the formula (3),
in the formula, rsIs the radial distance, r, from the core fiber axis to the rigid layer-outer protective layer interfaceoIs the radial distance, r, from the core fiber axis to the outer protective layer-adhesive layer interfaceaIs the radial distance, tau, from the axis of the core fiber to the adhesive layer-substrate interfacesIs the shear stress at the rigid layer-outer protective layer interface, epsilonsIs positively strained by the rigid layer, τo,rIs the shear stress, tau, of a certain interface in the outer protective layer at a distance r from the axis of the fibera,rShear stress at a certain interface in the adhesive layer at a distance r from the axis of the optical fiber, AsIs the cross-sectional area of the rigid layer, DaFor width of adhesive layer, Es、Eo、EaThe elastic modulus, σ, of the rigid layer, the outer protective layer and the adhesive layers、σo、σaRespectively the normal stress of the rigid layer, the outer protective layer and the adhesive layer, dx is the length of the optical fiber micro-segment, Go、GaShear modulus of the outer protective layer and the adhesive layer, um、usAxial deformation of the substrate, respectively of the rigid layer,. tauo,roThe shear stress of the interface at the position of ro away from the optical fiber axis in the outer protective layer;
step two: calculating the composite protective layer-adhesive layer-substrate strain transfer rate alpha according to the formula (4) by using a composite protective layer-adhesive layer-substrate strain transfer model based on a shear-lag theory2，
Wherein epsilonmDenotes the strain of the substrate, k2Denotes alpha2And calculating the shear lag parameters in the process.
The fourth concrete implementation mode: in this embodiment, the first embodiment is further explained, and the strain transmittance correction method in the third step is:
step three, firstly: according to actual layout conditions, an optical fiber-composite protective layer-adhesive layer-matrix numerical model is established, and a numerical simulation calculation result alpha of the strain transmissibility of the sensing optical cable is obtained through calculationM，
αM＝[αM1,αM2,...,αMi,...,αMN] (6)
In the formula, alphaMiFor the calculation result of the strain transfer rate at the ith node in the numerical model, the numerical model is divided into N nodes in total, alphaMNCalculating a result for a strain transfer rate at an nth node in the numerical model;
step three: comprehensively considering the strain transmissibility alpha of the core optical fiber-composite protective layer1With composite protective layer-adhesive layer-base body strain transmissibility alpha2A theoretical value alpha of the strain transfer rate is calculated according to the formula (7),
step three: according to the node division positions in the numerical model, the strain transmissibility alpha of the multiple nodes is constructed by adopting the formula (7)T，
αT＝[αT1,αT2,...,αTi,...,αTN] (8)
In the formula, alphaTiFor the theoretical calculation result of the strain transfer rate at the ith node, the numerical model is divided into N nodes, alphaTNThe theoretical calculation result of the strain transfer rate at the Nth node is obtained;
step three and four: the reference quantity S is calculated according to equation (9),
S＝(αM-αT)(αM-αT)T (9)
calculating the shear lag parameter k in the equations (2) and (5) respectively by using the equation (10)1And k2Has a correction coefficient of gamma1And gamma2，
k1′＝γ1k1,k2′＝γ2k2 (10)
In the formula, k1' and k2' represents the shear parameter k in the formulae (2) and (5), respectively1、k2The corrected result of (1);
substituting the formula (10) into the formulas (7) to (9), calculating the updated S, taking the correction coefficient when the reference quantity S is minimum as the optimal correction coefficient, and finally calculating the strain transfer rate alpha of the corrected optical fiber-composite protective layer-adhesive layer-substrate according to the formula (11)*，
In the formula (I), the compound is shown in the specification,
is the optimum correction factor.
The fifth concrete implementation mode: in this embodiment, the first specific embodiment is further explained, and the method for calculating the strain transfer rate of the optical fiber-composite protective layer-adhesive layer-substrate considering the influence of the optical cable construction installation factors in the fourth step is as follows:
after the sensing optical cable is laid and installed, the pasting quality is checked, and the pasting length l of the optical cable is recorded section by section; randomly selecting proper points along the line, recording the corresponding effective pasting width D and the pasting thickness h, and calculating the mean value mu of l, D and hl、μD、μhSum variance σl、σD、σhXIs measured byl、μD、μhSubstituted in formula (5) and formula (4) for L, D in the original formulaa、ra－roFinally obtaining the optical fiber-composite protective layer-adhesive layer-matrix strain transfer rate alpha considering the influence of construction and installation factors of the sensing optical cable*，
Example (b):
the finite element model of a certain distributed sensing optical cable is taken as an example in the embodiment, and the effectiveness of the calculation method for the distributed optical fiber-protective layer-adhesive layer-matrix strain transfer provided by the invention is verified. The distributed sensing optical cable is shown in fig. 2, a numerical model is established by using finite element software ANSYS, all parts of the model are simulated by using solid185 units, the material and shape parameters are shown in table 1, and the finite element model is shown in fig. 3.
TABLE 1 model parameter value-taking table
Fig. 4 to 6 show the results of numerical simulation calculation of the strain transmissibility of the sensing optical cable and the results before correction of the shear-lag parameter calculated by the formula (7) in the case where the sticking lengths of the optical cables are 20cm, 30cm and 40cm, respectively. The results of the modified shear-lag parameters calculated by the formula (11) and the results of numerical simulation calculations are shown in fig. 7 to 9, based on a finite element model with a pasting length of 20 cm.
As can be seen from fig. 4 to 6, a large error exists between the strain of the core optical fiber of the sensing optical cable and the actual strain of the structure, and the strain transfer rate of the sensing optical cable needs to be calculated. As can be seen from fig. 7 to 9, after the finite element model with the pasting length of 20cm is corrected for the shear-lag parameters, the theoretically calculated strain transmissibility is matched with the numerical simulation result at each pasting length, which shows that the method provided by the present invention can realize the accurate calculation of the strain transmissibility of the optical fiber, the composite protective layer, the pasting layer and the substrate.
Claims (1)
1. A method for calculating strain transmission of distributed optical fiber-protective layer-adhesive layer-substrate is characterized by comprising the following steps:
the method comprises the following steps: determining the rigidity index of the optical fiber composite protective layer according to the adopted cross-section parameters of the distributed sensing optical cable, constructing a shearing relation model of the core optical fiber and the composite protective layer, and calculating the strain transfer rate of the core optical fiber-the composite protective layer; the specific calculation steps are as follows:
the method comprises the following steps: dividing the composite protective layer into an inner protective layer, a rigid layer and an outer protective layer by taking a rigid layer in the composite protective layer as a boundary, determining the section size and material parameters of each layer in a layering manner, constructing a shearing relation model of the core optical fiber and the composite protective layer as shown in the formula (1),
in the formula, rfIs the radial distance, r, from the core fiber axis to the core fiber-inner protective layer interfaceiIs the radial distance, τ, from the core fiber axis to the inner protective layer-rigid layer interfacefIs the shear stress, epsilon, at the core fiber-inner protective layer interfacefIs a corePositive strain of optical fiber, taui,rShear stress at a certain interface in the inner protective layer at a distance r from the axis of the optical fiber, Ef、EiRespectively, the elastic modulus of the core fiber and the inner protective layer, dx is the fiber micro-segment length, GiIs the shear modulus of the inner protective layer, uf、usAxial deformation of the core optical fiber and the rigid layer respectively;
the first step is: calculating the strain transmissibility alpha of the core optical fiber and the composite protective layer by the formula (2) by using a shearing relation model of the core optical fiber and the composite protective layer1，
Wherein L is the sticking length of the sensing optical cable, epsilonsIs positively strained by the rigid layer, alpha1Denotes the strain transfer rate, k, from the paste end point x1Denotes alpha1Calculating shear lag parameters in the process, wherein cosh (·) represents a hyperbolic cosine function;
step two: determining the thickness and shear modulus of the pasting layer of the distributed sensing optical cable according to the field laying condition of the distributed sensing optical cable, and calculating the strain transfer rate of the composite protective layer, the pasting layer and the matrix based on the shear hysteresis theory; the specific calculation steps are as follows:
step two, firstly: determining the size and material properties of the adhesive layer of the sensing optical cable, constructing a composite protective layer-adhesive layer-matrix strain transfer model based on a shear hysteresis theory according to the formula (3),
in the formula, rsIs the radial distance, r, from the core fiber axis to the rigid layer-outer protective layer interfaceoIs the radial distance, r, from the core fiber axis to the outer protective layer-adhesive layer interfaceaIs the radial distance, tau, from the axis of the core fiber to the adhesive layer-substrate interfacesIs the shear stress at the rigid layer-outer protective layer interface, epsilonsIs a rigid layer shouldChange, tauo,rIs the shear stress, tau, of a certain interface in the outer protective layer at a distance r from the axis of the fibera,rShear stress at a certain interface in the adhesive layer at a distance r from the axis of the optical fiber, AsIs the cross-sectional area of the rigid layer, DaFor width of adhesive layer, Es、Eo、EaThe elastic modulus, σ, of the rigid layer, the outer protective layer and the adhesive layers、σo、σaRespectively the normal stress of the rigid layer, the outer protective layer and the adhesive layer, dx is the length of the optical fiber micro-segment, Go、GaShear modulus of the outer protective layer and the adhesive layer, um、usRespectively axial deformation of the substrate and the rigid layer,
the shear stress of the interface at the position of ro away from the optical fiber axis in the outer protective layer;
step two: calculating the composite protective layer-adhesive layer-substrate strain transfer rate alpha according to the formula (4) by using a composite protective layer-adhesive layer-substrate strain transfer model based on a shear-lag theory2，
Wherein epsilonmDenotes the strain of the substrate, k2Denotes alpha2Calculating shear lag parameters in the process;
step three: establishing an optical fiber-composite protective layer-adhesive layer-matrix numerical model of distributed optical fiber sensing according to field layout conditions, and correcting and calculating shear hysteresis parameters of the strain transmissibility in the first step and the second step according to a minimum error principle to obtain a result after the strain transmissibility correction of the optical fiber-composite protective layer-adhesive layer-matrix; the strain transmissibility correction method comprises the following steps:
step three, firstly:according to actual layout conditions, an optical fiber-composite protective layer-adhesive layer-matrix numerical model is established, and a numerical simulation calculation result alpha of the strain transmissibility of the sensing optical cable is obtained through calculationM，
αM＝[αM1,αM2,...,αMi,...,αMN] (6)
In the formula, alphaMiFor the calculation result of the strain transfer rate at the ith node in the numerical model, the numerical model is divided into N nodes in total, alphaMNCalculating a result for a strain transfer rate at an nth node in the numerical model;
step three: comprehensively considering the strain transmissibility alpha of the core optical fiber-composite protective layer1With composite protective layer-adhesive layer-base body strain transmissibility alpha2A theoretical value alpha of the strain transfer rate is calculated according to the formula (7),
step three: according to the node division positions in the numerical model, the strain transmissibility alpha of the multiple nodes is constructed by adopting the formula (7)T，
αT＝[αT1,αT2,...,αTi,...,αTN] (8)
In the formula, alphaTiFor the theoretical calculation result of the strain transfer rate at the ith node, the numerical model is divided into N nodes, alphaTNThe theoretical calculation result of the strain transfer rate at the Nth node is obtained;
step three and four: the reference quantity S is calculated according to equation (9),
S＝(αM-αT)(αM-αT)T (9)
calculating the shear lag parameter k in the equations (2) and (5) respectively by using the equation (10)1And k2Has a correction coefficient of gamma1And gamma2，
k1′＝γ1k1,k2′＝γ2k2 (10)
In the formula, k1' and k2' represents the shear parameter k in the formulae (2) and (5), respectively1、k2The corrected result of (1);
substituting the formula (10) into the formulas (7) to (9), calculating the updated S, taking the correction coefficient when the reference quantity S is minimum as the optimal correction coefficient, and finally calculating the strain transfer rate alpha of the corrected optical fiber-composite protective layer-adhesive layer-substrate according to the formula (11)*，
In the formula (I), the compound is shown in the specification,
is the optimal correction coefficient;
step four: after the distributed sensing optical cable is installed on site, testing to obtain indexes of the thickness, the width and the length of the optical cable adhesive layer, summarizing and analyzing statistical characteristics of parameter indexes of the optical cable adhesive layer, substituting the statistical characteristics into the step three, and calculating an optical fiber-composite protective layer-adhesive layer-matrix strain transmission result considering the influence of optical cable construction installation factors; the specific calculation method is as follows:
after the sensing optical cable is laid and installed, the pasting quality is checked, and the pasting length l of the optical cable is recorded section by section; randomly selecting proper points along the line, recording the corresponding effective pasting width D and the pasting thickness h, and calculating the mean value mu of l, D and hl、μD、μhSum variance σl、σD、σhXIs measured byl、μD、μhSubstituted in formula (5) and formula (4) for L, D in the original formulaa、ra－roFinally obtaining the optical fiber-composite protective layer-adhesive layer-matrix strain transfer rate alpha considering the influence of construction and installation factors of the sensing optical cable*，
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