Complex boundary short cable force monitoring method and system

Abstract

The invention discloses a complex boundary short cable force monitoring method and system, and particularly relates to the field of construction monitoring, and the method comprises the following steps: I, installing a steel cable clamp and a tensioning structure, installing an anti-torsion device at the top of the cable clamp, and arranging various sensors at specified positions; iI, state information of the short cable structure is collected in real time through various sensors, and the collected state information of each group is preprocessed; iII, dynamically correcting the measurement error according to the geometric structure and material characteristics of the short cable based on each group of state information after preprocessing; iV, establishing a force conversion relation model, and extracting and updating a dynamic calibration cable force conversion coefficient in real time in different loading stages of tensioning construction; according to the invention, strain offset caused by member torsion can be avoided, the cable force measurement precision is improved, the strain identification capability is effectively enhanced, the effectiveness and reliability of long-term monitoring are guaranteed, and the monitoring stability under boundary interference is improved.

Description

Technical Field

[0001] The present invention relates to the field of construction monitoring, and in particular to a method and system for monitoring the force of short cables with complex boundaries. Background Art

[0002] In steel structures, whether bridges or long-span spatial structures, short cables often serve as core load-bearing components, playing a crucial role in force transmission and stability. However, due to their complex force paths and variable boundary conditions, especially when the cables are limited in length, densely arranged, and have uneven boundary stiffness, their mechanical response exhibits significant nonlinear characteristics, posing a significant challenge to accurately monitoring their cable forces. Accurately determining the cable forces under complex boundary conditions has long been a technical difficulty and industry pain point that the engineering community has struggled to effectively address.

[0003] Short cables are small, have high natural frequencies, and exhibit weak vibration responses. These cables are also susceptible to interference from external factors such as temperature fluctuations, structural deformation, and construction disturbances. This makes it difficult for traditional cable tension monitoring methods to achieve the desired accuracy in practical applications. Currently, cable tension monitoring methods widely used in engineering projects include the oil gauge method, the dual-control elongation method, the annular pressure sensor method, the magnetic flux sensor method, and the frequency method. However, these methods all have varying degrees of limitations in monitoring the tension of short cables. Therefore, monitoring the tension of short cables constrained by complex boundaries, a long cable, is difficult to achieve using existing technologies. Therefore, a method and system for monitoring the tension of short cables with complex boundaries is proposed.

[0004] Existing short cable force monitoring method and system; To this end, we propose a short cable force monitoring method and system with complex boundaries. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem and propose a short rope force monitoring method and system for complex boundaries.

[0006] In a first aspect of the present invention, a method and system for monitoring the force of short cables at complex boundaries are first proposed. The method comprises:

[0007] Ⅰ. Install the cable clamp and tensioning structure, install an anti-twist device on the top of the cable clamp, and then arrange various sensors at the specified positions;

[0008] II. Collect the status information of the short cable structure in real time through various sensors, and pre-process the collected status information;

[0009] III. Based on the pre-processed state information of each group, the measurement error is dynamically corrected according to the structural geometry and material properties;

[0010] IV. Establish a force conversion relationship model and extract and update the dynamic calibration cable force conversion coefficient in real time at different loading stages of tensioning construction;

[0011] V. Calculate the cable force boundary constraints of the short cable structure based on each state information, and dynamically modify the effective cable force value of the short cable based on the boundary constraint conditions;

[0012] VI. During the tensioning stages of each level of construction, various status data are continuously recorded. At the same time, various parameters of short cable force monitoring are dynamically adjusted based on the real-time recording results.

[0013] As a further solution of the present invention, the specific steps of installing the cable clamp and tensioning structure in step I, installing an anti-twist device on the top of the cable clamp, and then arranging various sensors at specified positions are as follows:

[0014] S1.1: Install the cable clamp assembly at the designated short cable location and complete the initial tensioning. Then, install the anti-twist device symmetrically on both sides of the cable clamp. After installing the anti-twist device on both sides, check whether the main axis of the anti-twist device and the cable axis coincide. If not, reinstall the device.

[0015] S1.2: After the anti-twist device is installed, weld the fiber Bragg grating strain sensor to the outer surface of the anti-twist device. During welding, make sure the axis of the fiber Bragg grating strain sensor coincides with the axis of the cable and the gauge length is consistent.

[0016] S1.3: Lay the transmission optical cable along the cable structure wiring path and secure it securely. Use a fiber fusion splicer to perform high-precision fusion splicing of the optical cable and the jumper at the end of the FBG strain sensor, with a fusion loss of less than 0.03 dB. Then, fusion splice an FC / APC connector to the end of the optical cable away from the FBG strain sensor and connect it to the FBG demodulator.

[0017] As a further solution of the present invention, the specific steps of pre-processing the collected status information of each group in step II are as follows:

[0018] S2.1: Set the acquisition parameters of the data acquisition instrument and fiber demodulator to a unified sampling frequency, data window length, and time alignment mechanism. The data acquisition instrument and fiber demodulator then acquire the voltage signal from the resistance strain gauge and the demodulated wavelength change value from the fiber Bragg grating strain sensor, respectively. These instruments then use basic conversion relationships to obtain the corresponding instantaneous microstrain values.

[0019] S2.2: Deploy independent temperature-sensitive optical fibers to acquire short-cable temperature data in real time. A multi-point difference method is used to isolate the temperature effect to obtain the actual mechanical microstrain value. A sliding average filter is then used to eliminate high-frequency random noise in the instantaneous microstrain values ​​and the mechanical microstrain values.

[0020] S2.3: Calculate the strain residual values ​​of different sensors. If the strain residual value is higher than the set tolerance, trigger the warning mechanism and recheck the data source or calibration coefficient. After the data preprocessing is completed, extract the peak strain, average strain, and fluctuation amplitude of each instantaneous microstrain value and the mechanical microstrain value as the short cable response parameters under the tensioning condition.

[0021] As a further solution of the present invention, the specific calculation formula of the microstrain value described in S2.1 is as follows:

[0022]

[0023] Where, ε FBG (t1) represents the instantaneous strain measured by the fiber Bragg grating strain sensor at time t1; Δλ(t1) represents the wavelength change at time t1; k λ represents the optical fiber strain sensitivity constant; ε res (t1) represents the instantaneous strain measured by the resistance strain gauge at time t1; V res (t1) represents the output voltage of the resistance strain gauge at time t1; k v represents the calibration factor of the resistance strain gauge;

[0024] The specific calculation formula of the multi-point difference method described in S2.2 is as follows:

[0025]

[0026] Where, ε mech (t1) represents the actual mechanical strain at time t1; represents the temperature strain coefficient; ΔT1(t1) represents the temperature change measured at time t1.

[0027] As a further solution of the present invention, the specific steps of dynamically correcting the measurement error according to the geometric structure and material properties of the pendant in step III are as follows:

[0028] S3.1: Select the tensioning end or mid-span section of the short cable and determine the spatial distribution of the sensors deployed on the selected section. Then format and process the strain values ​​measured by each sensor to construct the strain vector for the short cable.

[0029] S3.2: Based on the elastic modulus of the steel at each sensor installation location, establish the corresponding short cable stiffness matrix. Based on the short cable strain vector and the corresponding short cable stiffness matrix, establish the Hooke relation matrix for the three-dimensional isotropic material. Simultaneously, obtain the corresponding stress vector of the short cable through matrix multiplication.

[0030] S3.3: Based on the stress vector of the short cable and the principle of force balance on the material cross section, establish a spatial force balance equation corresponding to the selected short cable cross section. Set the spatial balance condition of the short cable when there is no external load as a constraint. Then, based on the established spatial force balance equation, obtain the additional bending moment of the corresponding short cable caused by the asymmetric boundary.

[0031] S3.4: If the additional bending moment is not zero, it indicates that the current short cable structure is disturbed by the additional bending moment, and the axial cable force of the short cable is corrected. At the same time, the corresponding conversion relationship is updated based on the corrected axial cable force of the short cable and the output of the resistance strain gauge.

[0032] As a further solution of the present invention, the strain values ​​described in S3.1 specifically include the strain in the axial direction of the short cable, the strain in the horizontal direction normal to the short cable, the strain in the vertical direction normal to the short cable, and the shear strain in the angle direction between the main axis and the vertical.

[0033] As a further solution of the present invention, the short cable stiffness matrix described in S3.2 is specifically expressed as follows:

[0034]

[0035] Where, E s Represents the elastic modulus of the steel material where each sensor is installed; μ s represents the Poisson's ratio of the short cable steel;

[0036] The specific calculation formula for the spatial force balance equation described in S3.3 is as follows:

[0037] ∑F x =∫ A σ xx dA=T eff

[0038] ∑F y =∫ A σ yy dA≈0

[0039] ∑M z =∫ A y·σ xx dA=M b

[0040] Where, ∑F x represents the resultant force balance of the short cable section in the x-axis direction; σ xx represents the axial stress; A represents the effective cross-sectional area of ​​the short cable core; T eff represents the equivalent axial force of the short cable; ∑F y represents the resultant force balance of the short cable section in the y-axis direction; σ yy represents vertical stress; ∑M zrepresents the moment balance of the short cable section around the z axis; y represents the distance of each point in the section relative to the neutral axis; M b Represents the additional bending moment generated by the short cable due to the asymmetric boundary.

[0041] In a second aspect of the present invention, a short cable force monitoring system for complex boundaries is proposed, comprising: a working condition input module, an anti-twist installation module, a sensor integration module, a signal acquisition module, an interference suppression module, a tension acquisition module, a spatial balance module, a calibration and identification module, a boundary inversion module, a cable force visualization module, a feedback verification module, and a storage and archiving module;

[0042] The working condition input module is used to input structural design parameters and construction working condition information;

[0043] The anti-twist installation module is used to control the axial stiffness direction of the short rope where the anti-twist device is arranged;

[0044] The sensor integration module is used to select and deploy a variety of sensor combinations;

[0045] The signal acquisition module is used to collect the vibration and various strain data of the short rope in real time;

[0046] The interference suppression module is used to eliminate the influence of environmental factors on various strain data during the short cable force monitoring process;

[0047] The tensioning acquisition module is used to synchronously record various sensor data according to predetermined stages during tensioning construction;

[0048] The spatial balance module is used to establish a corresponding spatial force balance equation based on the short cable cross section and dynamically correct the short cable force monitoring error generated;

[0049] The calibration identification module is used to construct the initial calibration factor and iteratively update the calibration factor during the entire tensioning process;

[0050] The boundary inversion module is used to calculate the boundary support force and constraint deformation, and correct the near-field force error at the cable end;

[0051] The cable force visualization module is used to generate a time history curve of the effective cable force of the corresponding short cable based on the output of each sensor and the cable force correction, and to display the cable force changes at each stage in real time in a graphical form;

[0052] The feedback verification module is used to compare the measured cable forces at each tensioning stage with the theoretical values, and to verify the convergence of the calibration factors and the consistency of the cable force calculations. At the same time, it automatically triggers an early warning for any abnormalities in the inspection.

[0053] The storage and archiving module is used to collect timestamp records of various data, classify and store them, and back them up in the cloud.

[0054] As a further solution of the present invention, the specific steps of constructing the initial calibration factor and iteratively updating it in real time are as follows:

[0055] S4.1: After each tension control force is applied to a steady state, the fiber Bragg grating wavelength drift value of the fiber Bragg grating strain sensor and the voltage value output by the resistance strain gauge under the same working conditions are simultaneously obtained. The fiber Bragg grating wavelength drift value is then converted to a fiber strain value using a Bragg grating strain conversion formula;

[0056] S4.2: The fiber strain value is converted into the axial force of the corresponding short cable through the spatial balance module, and the obtained short cable axial force is fitted with the voltage value output by the resistance strain gauge to calculate the corresponding initial calibration factor. An increase of 10% in tensioning force is regarded as a tensioning level. After that, when each tensioning level is completed, the synchronous data pair of the fiber Bragg grating strain sensor and the resistance strain gauge is collected again, and the calibration factor is updated.

[0057] As a further solution of the present invention, the specific calculation formula for updating the calibration factor in S4.2 is as follows:

[0058]

[0059] Where K i represents the updated calibration factor of the i-th tensioning level; α represents the smoothing factor, and its value range is [0, 1]; K i-1 represents the calibration factor of the i-1th tension level; F ref,i represents the reference cable force of the short cable at the i-th tensioning level; V r,i Represents the voltage output of the resistance strain gauge at the i-th tensioning level.

[0060] Beneficial effects of the present invention:

[0061] The present invention proposes a method and system for monitoring the tension of short cables with complex boundaries. The method comprises installing a steel cable clamp and an anti-torsion device at a set position of the short cable to ensure that its axis is aligned with the cable, welding a fiber optic Bragg grating strain sensor, laying an optical cable and fusing it to a demodulation system with high precision, constructing a synchronous acquisition chain of a resistance strain gauge and an optical fiber system, unifying sampling parameters, correcting temperature strain through real-time temperature-sensitive optical fiber, combining sliding filtering to process noise, extracting micro-strain eigenvalues ​​and constructing a strain vector, then generating a stiffness matrix based on the elastic modulus of the steel, establishing a spatial force balance equation to obtain the stress vector and axial force, correcting errors caused by additional bending moment interference, collecting optical fiber and resistance strain data at each tensioning level, establishing and dynamically updating calibration factors, and monitoring the actual tension value of the short cable in real time. This method can avoid strain offset caused by component torsion, improve cable tension measurement accuracy, effectively enhance strain recognition capability, ensure the effectiveness and reliability of long-term monitoring, and improve monitoring stability under boundary interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The present invention will be further described below with reference to the accompanying drawings.

[0063] Figure 1 A flow chart of a method for monitoring short cable forces at complex boundaries provided by an embodiment of the present invention;

[0064] Figure 2 A framework diagram of a short rope force monitoring system for complex boundaries provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0066] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0067] The embodiment of the present invention provides a method and system for monitoring the force of short cables in complex boundaries. Figure 1 , Figure 1 A flowchart of a method for monitoring the force of a short cable at a complex boundary provided by an embodiment of the present invention. The method comprises the following steps:

[0068] Install the cable clamp and tensioning structure, install an anti-twist device on the top of the cable clamp, and then arrange various sensors at the specified positions.

[0069] Specifically, a steel cable clamp assembly is installed at a predetermined short cable position, and the initial tensioning operation is completed. Then, anti-torsion devices are installed symmetrically on both sides of the steel cable clamp. After the anti-torsion devices on both sides are installed, it is detected whether the main axis of the anti-torsion device coincides with the axis of the steel cable. If not, reinstall it. After the anti-torsion device is installed, the fiber optic Bragg grating strain sensor is welded to the outer surface of the anti-torsion device. During welding, the axis of the fiber optic Bragg grating strain sensor is made to coincide with the axis of the cable, and the gauge length is consistent. The transmission optical cable is laid along the wiring path of the cable structure and firmly fixed. A fiber optic fusion splicer is used to perform high-precision fusion of the optical cable and the jumper at the end of the fiber optic Bragg grating strain sensor, and the fusion loss is less than 0.03dB. An FC / APC connector is then fusion-spliced ​​at the end of the optical cable away from the fiber optic Bragg grating strain sensor, and connected to the fiber optic Bragg grating demodulator.

[0070] It should be further explained that the cable clamp is made of spring steel and prestressed on the circumference by controlling the bolt torque, and is combined with an anti-torsion device on the top so that the resistance strain gauge deforms synergistically with the elongation of the cable, and the cable force is calculated based on the strain parameters measured by the resistance strain gauge.

[0071] In addition, it should be noted that the fiber Bragg grating strain sensor has a wavelength range of 1510-1590nm; the customized center wavelength deviation is ±0.5pm; the reflectivity is ≥80%; the 3dB bandwidth is 0.1-1nm; the grating region length is 2mm-20mm; the side mode suppression ratio is >15dB; the fiber type is SMF-28, Polyi mide fiber; the coating method and type is polyimide; the tensile strength is ≥100kpsi; the fiber interface is FC / APC; and the operating temperature is -40℃ to 120℃ or -200℃ to 300℃.

[0072] The resistance strain gauge has a gauge length L of 76 mm, an effective diameter d of 114*32*12.5 mm, a hole diameter D of 10 mm, a measuring range of ±1000 με, a sensitivity of approximately 500 με / mV / V, a resolution of ≤0.015% FS, a bridge voltage of ≤10 VDC, a bridge resistance of 350 Ω, nonlinearity of ≤1.5% FS, a drift of ≤±3 με, an IP65 protection rating, a temperature range of -20 to 60°C, and a weight of 95 g.

[0073] Various state information of the short rope structure is collected in real time through various sensors, and each set of collected state information is preprocessed.

[0074] Specifically, the acquisition parameters of the data acquisition instrument and the fiber optic demodulator are set to a unified sampling frequency, data window length, and time alignment mechanism. Then, the data acquisition instrument and the fiber optic demodulator respectively obtain the voltage signal from the resistance strain gauge and the demodulated wavelength change value from the fiber grating strain sensor, and obtain the corresponding instantaneous microstrain value through the basic conversion relationship. The temperature data of the short cable is obtained in real time by laying an independent temperature-sensitive optical fiber, and the temperature influence is separated by a multi-point difference method to obtain the actual mechanical microstrain value. The high-frequency random noise in each instantaneous microstrain value and the mechanical microstrain value is eliminated by sliding average filtering, and the strain residual values ​​of different sensors are calculated. If the strain residual value is higher than the set tolerance, the early warning mechanism is triggered and the data source or calibration coefficient is rechecked. After the preprocessing of various data is completed, the peak strain, average strain, and fluctuation amplitude characteristics of each instantaneous microstrain value and the mechanical microstrain value are extracted as the short cable response parameters under the tensioning condition.

[0075] It should be further explained that the specific calculation formula of the micro-strain value is as follows:

[0076]

[0077]

[0078] Where, ε FBG (t1) represents the instantaneous strain measured by the fiber Bragg grating strain sensor at time t1; Δλ(t1) represents the wavelength change at time t1; k λ represents the optical fiber strain sensitivity constant; ε res (t1) represents the instantaneous strain measured by the resistance strain gauge at time t1; V res (t1) represents the output voltage of the resistance strain gauge at time t1; k v represents the calibration factor of the resistance strain gauge;

[0079] The specific calculation formula of the multi-point difference method is as follows:

[0080]

[0081] Where, ε mech (t1) represents the actual mechanical strain at time t1; represents the temperature strain coefficient; ΔT1(t1) represents the temperature change measured at time t1.

[0082] Based on the preprocessed state information of each group, the measurement error is dynamically corrected according to the geometric structure and material properties of the short cable.

[0083] Specifically, the tensioning end or mid-span section of the short cable is selected, and the spatial distribution of each sensor arranged on the selected section is determined. The strain values ​​measured by each sensor are then formatted to construct the short cable strain vector. According to the elastic modulus of the steel at the installation location of each sensor, the corresponding short cable stiffness matrix is ​​established. Based on the short cable strain vector and the corresponding short cable stiffness matrix, the Hooke relationship matrix of the three-dimensional isotropic material is established. At the same time, the stress vector corresponding to the short cable is obtained through matrix multiplication. According to the stress vector of the short cable and the force balance principle on the material cross section, the spatial force balance equation corresponding to the selected short cable section is established, and the spatial balance condition of the short cable when there is no external load is set as a constraint. Then, based on the established spatial force balance equation, the additional bending moment generated by the asymmetric boundary of the corresponding short cable is obtained. If the additional bending moment is not zero, it indicates that the current short cable structure is disturbed by the additional bending moment, and the axial cable force of the short cable is corrected. At the same time, the corresponding conversion relationship is updated according to the corrected axial cable force and the output of the resistance strain gauge.

[0084] It should be further explained that the various strain values ​​specifically include the strain in the axial direction of the short cable, the strain in the horizontal direction normal to the short cable, the strain in the vertical direction normal to the short cable, and the shear strain in the angle direction between the main axis and the vertical.

[0085] In addition, it should be noted that the short cable stiffness matrix is ​​specifically expressed as follows:

[0086]

[0087] Where, E s Represents the elastic modulus of the steel material where each sensor is installed; μ s represents the Poisson's ratio of the short cable steel;

[0088] The specific calculation formula of the spatial force balance equation is as follows:

[0089] ∑F x =∫ A σ xx dA=T eff

[0090] ∑F y =∫ A σ yy dA≈0

[0091] ∑M z =∫ A y·σ xx dA=M b

[0092] Where, ∑F x represents the resultant force balance of the short cable section in the x-axis direction; σ xx represents the axial stress; A represents the effective cross-sectional area of ​​the short cable core; T eff represents the equivalent axial force of the short cable; ∑F y represents the resultant force balance of the short cable section in the y-axis direction; σ yy represents vertical stress; ∑M z represents the moment balance of the short cable section around the z axis; y represents the distance of each point in the section relative to the neutral axis; M b Represents the additional bending moment generated by the short cable due to the asymmetric boundary.

[0093] A force conversion relationship model is established, and the dynamic calibration cable force conversion coefficient is extracted and updated in real time at different loading stages of tensioning construction.

[0094] According to the state information, the boundary constraints of the short cable structure are calculated, and based on the boundary constraints, the effective cable force value of the short cable is dynamically corrected.

[0095] During the tensioning stages of each level of construction, various status data are continuously recorded, and the various parameters of the short cable force monitoring are dynamically adjusted based on the real-time recording results.

[0096] Based on the same inventive concept, the present invention also provides a short rope force monitoring system for complex boundaries. Figure 2 , Figure 2A structural schematic diagram of a short rope force monitoring system for complex boundaries provided in an embodiment of the present invention includes: a working condition input module, an anti-twist installation module, a sensor integration module, a signal acquisition module, an interference suppression module, a tension acquisition module, a spatial balance module, a calibration and identification module, a boundary inversion module, a rope force visualization module, a feedback verification module and a storage and archiving module.

[0097] The working condition input module is used to input structural design parameters and construction working condition information; the anti-torsion installation module is used to control the axial stiffness direction of the short cable at the anti-torsion device layout; the sensor integration module is used to select and layout a variety of sensor combinations; the signal acquisition module is used to collect short cable vibration and various strain data in real time; the interference suppression module is used to eliminate the influence of environmental factors in the various strain data during the short cable force monitoring process; the tensioning acquisition module is used to synchronously record various sensor data according to the predetermined stages during the tensioning construction.

[0098] The spatial balance module is used to establish the corresponding spatial force balance equation based on the short cable cross-section and dynamically correct the short cable force monitoring error; the calibration identification module is used to construct the initial calibration factor and update it in real time.

[0099] Specifically, after each tensioning control force is applied to a steady state, the fiber Bragg grating (FBG) strain sensor's wavelength drift value and the voltage output of the resistance strain gauge under the same operating conditions are synchronously acquired. The fiber Bragg grating (FBG) wavelength drift value is then converted to fiber strain using the FBG strain conversion formula. The fiber strain value is converted to the corresponding axial force of the short cable using a spatial balance module. The acquired axial force of the short cable is then fitted with the voltage output of the resistance strain gauge to calculate the corresponding initial calibration factor. A 10% increase in tension is considered a tensioning level. After each tensioning level is completed, synchronized data pairs from the fiber Bragg grating (FBG) strain sensor and the resistance strain gauge are collected again, and the calibration factor is updated.

[0100] It should be further explained that the specific calculation formula for updating the calibration factor is as follows:

[0101]

[0102] Where K i represents the updated calibration factor of the i-th tensioning level; α represents the smoothing factor, and its value range is [0, 1]; K i-1 represents the calibration factor of the i-1th tension level; F ref,i represents the reference cable force of the short cable at the i-th tensioning level; V r,i Represents the voltage output of the resistance strain gauge at the i-th tensioning level.

[0103] The boundary inversion module is used to calculate the boundary support force and constraint deformation, and correct the near-field force error at the cable end; the cable force visualization module is used to generate the effective cable force time history curve of the corresponding short cable based on the output of each sensor and the cable force correction, and to display the cable force changes in each stage in real time in the form of a graph; the feedback verification module is used to compare the measured cable force and the theoretical value in each tensioning stage, and to test the convergence of the calibration factor and the consistency of the cable force calculation, and automatically trigger an early warning for abnormal inspection conditions; the storage and archiving module is used to collect timestamp records of various data, classify storage and cloud backup.

[0104] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for monitoring the force of short cables on complex boundaries, characterized in that: The following steps are involved: Ⅰ. Install the cable clamp and tensioning structure, install an anti-twist device on the top of the cable clamp, and then arrange various sensors at the specified positions; II. Collect the status information of the short cable structure in real time through various sensors, and pre-process the collected status information; III. Based on the pre-processed state information of each group, the measurement error is dynamically corrected according to the geometric structure and material properties of the short cable; IV. Establish a force conversion relationship model and extract and update the dynamic calibration cable force conversion coefficient in real time at different loading stages of tensioning construction; V. Calculate the cable force boundary constraints of the short cable structure based on each state information, and dynamically modify the effective cable force value of the short cable based on the boundary constraint conditions; VI. During the tensioning stages of each level of construction, various status data are continuously recorded. At the same time, various parameters of short cable force monitoring are dynamically adjusted based on the real-time recording results.

2. The method for monitoring the short rope force at a complex boundary according to claim 1, characterized in that: The specific steps for installing the cable clamp and tensioning structure as described in Step I, installing the anti-twist device on the top of the cable clamp, and then arranging various sensors at the specified locations are as follows: S1.1: Install the cable clamp assembly at the designated short cable location and complete the initial tensioning. Then, install the anti-twist device symmetrically on both sides of the cable clamp. After installing the anti-twist device on both sides, check whether the main axis of the anti-twist device and the cable axis coincide. If not, reinstall the device. S1.2: After the anti-twist device is installed, weld the fiber Bragg grating strain sensor to the outer surface of the anti-twist device. During welding, make sure the axis of the fiber Bragg grating strain sensor coincides with the axis of the cable and the gauge length is consistent. S1.3: Lay the transmission optical cable along the cable structure wiring path and secure it securely. Use a fiber fusion splicer to perform high-precision fusion splicing of the optical cable and the jumper at the end of the FBG strain sensor, with a fusion loss of less than 0.03 dB. Then, fusion splice an FC / APC connector to the end of the optical cable away from the FBG strain sensor and connect it to the FBG demodulator.

3. The method for monitoring the short rope force at a complex boundary according to claim 2, characterized in that: The specific steps of pre-processing the collected status information of each group in step II are as follows: S2.1: Set the acquisition parameters of the data acquisition instrument and fiber demodulator to a unified sampling frequency, data window length, and time alignment mechanism. The data acquisition instrument and fiber demodulator then acquire the voltage signal from the resistance strain gauge and the demodulated wavelength change value from the fiber Bragg grating strain sensor, respectively. These instruments then use basic conversion relationships to obtain the corresponding instantaneous microstrain values. S2.2: Deploy independent temperature-sensitive optical fibers to acquire short-cable temperature data in real time. A multi-point difference method is used to isolate the temperature effect to obtain the actual mechanical microstrain value. A sliding average filter is then used to eliminate high-frequency random noise in the instantaneous microstrain values ​​and the mechanical microstrain values. S2.3: Calculate the strain residual values ​​of different sensors. If the strain residual value is higher than the set tolerance, trigger the warning mechanism and recheck the data source or calibration coefficient. After the data preprocessing is completed, extract the peak strain, average strain, and fluctuation amplitude of each instantaneous microstrain value and the mechanical microstrain value as the short cable response parameters under the tensioning condition.

4. The method for monitoring the short cable force at a complex boundary according to claim 3, characterized in that: The specific calculation formula for the microstrain value described in S2.1 is as follows: Where, ε FBG (t1) represents the instantaneous strain measured by the fiber Bragg grating strain sensor at time t1; Δλ(t1) represents the wavelength change at time t1; k λ represents the optical fiber strain sensitivity constant; ε res (t1) represents the instantaneous strain measured by the resistance strain gauge at time t1; V res (t1) represents the output voltage of the resistance strain gauge at time t1; k v Represents the calibration factor of the resistance strain gauge; The specific calculation formula of the multi-point difference method described in S2.2 is as follows: Where, ε mech (t1) represents the actual mechanical strain at time t1; represents the temperature strain coefficient; ΔT1(t1) represents the temperature change measured at time t1.

5. The method for monitoring the short cable force at a complex boundary according to claim 3, characterized in that: The specific steps for dynamically correcting the measurement error according to the geometric structure and material properties of the pendant described in step III are as follows: S3.1: Select the tensioning end or mid-span section of the short cable and determine the spatial distribution of the sensors deployed on the selected section. Then format and process the strain values ​​measured by each sensor to construct the strain vector for the short cable. S3.2: Based on the elastic modulus of the steel at each sensor installation location, establish the corresponding short cable stiffness matrix. Based on the short cable strain vector and the corresponding short cable stiffness matrix, establish the Hooke relation matrix for the three-dimensional isotropic material. Simultaneously, obtain the corresponding stress vector of the short cable through matrix multiplication. S3.3: Based on the stress vector of the short cable and the principle of force balance on the material cross section, establish a spatial force balance equation corresponding to the selected short cable cross section. Set the spatial balance condition of the short cable when there is no external load as a constraint. Then, based on the established spatial force balance equation, obtain the additional bending moment of the corresponding short cable caused by the asymmetric boundary. S3.4: If the additional bending moment is not zero, it indicates that the current short cable structure is disturbed by the additional bending moment, and the axial cable force of the short cable is corrected. At the same time, the corresponding conversion relationship is updated based on the corrected axial cable force of the short cable and the output of the resistance strain gauge.

6. A short rope force monitoring system for complex boundaries, used to implement a short rope force monitoring method for complex boundaries according to any one of claims 1 to 5, characterized in that: include: Working condition input module, anti-twist installation module, sensor integration module, signal acquisition module, interference suppression module, tension acquisition module, spatial balance module, calibration and identification module, boundary inversion module, cable force visualization module, feedback verification module and storage and archiving module; The working condition input module is used to input structural design parameters and construction working condition information; The anti-twist installation module is used to control the axial stiffness direction of the short rope where the anti-twist device is arranged; The sensor integration module is used to select and deploy a variety of sensor combinations; The signal acquisition module is used to collect the vibration and various strain data of the short rope in real time; The interference suppression module is used to eliminate the influence of environmental factors on various strain data during the short cable force monitoring process; The tensioning acquisition module is used to synchronously record various sensor data according to predetermined stages during tensioning construction; The spatial balance module is used to establish a corresponding spatial force balance equation based on the short cable cross section and dynamically correct the short cable force monitoring error generated; The calibration identification module is used to construct the initial calibration factor and update it in real time; The boundary inversion module is used to calculate the boundary support force and constraint deformation, and correct the near-field force error at the cable end; The cable force visualization module is used to generate a time history curve of the effective cable force of the corresponding short cable based on the output of each sensor and the cable force correction, and to display the cable force changes at each stage in real time in a graphical form; The feedback verification module is used to compare the measured cable forces at each tensioning stage with the theoretical values, and to verify the convergence of the calibration factors and the consistency of the cable force calculations. At the same time, it automatically triggers an early warning for any abnormalities in the inspection. The storage and archiving module is used to collect timestamp records of various data, classify and store them, and back them up in the cloud.

7. The short rope force monitoring system for complex borders according to claim 6, characterized in that: The specific steps of the calibration identification module to construct the initial calibration factor and iteratively update it in real time are as follows: S4.1: After each tension control force is applied to a steady state, the fiber Bragg grating wavelength drift value of the fiber Bragg grating strain sensor and the voltage value output by the resistance strain gauge under the same working conditions are simultaneously obtained. The fiber Bragg grating wavelength drift value is then converted to a fiber strain value using a Bragg grating strain conversion formula; S4.2: The fiber strain value is converted into the axial force of the corresponding short cable through the spatial balance module, and the obtained short cable axial force is fitted with the voltage value output by the resistance strain gauge to calculate the corresponding initial calibration factor. An increase of 10% in tensioning force is regarded as a tensioning level. After that, when each tensioning level is completed, the synchronous data pair of the fiber Bragg grating strain sensor and the resistance strain gauge is collected again, and the calibration factor is updated.

8. The short rope force monitoring system for complex borders according to claim 7, characterized in that: The specific calculation formula for updating the calibration factor described in S4.2 is as follows: Where K i represents the updated calibration factor of the i-th tensioning level; α represents the smoothing factor, and its value range is [0, 1]; K i-1 represents the calibration factor of the i-1th tension level; F ref,i represents the reference cable force of the short cable at the i-th tensioning level; V ri Represents the voltage output of the resistance strain gauge at the i-th tensioning level.

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