Self-compensating grating measuring device and method for multi-parameter measurement of storage tank foundation

Abstract

The invention discloses a self-compensating grating measuring device and method for multi-parameter measurement of a storage tank foundation. The self-compensating grating measuring device comprises a plurality of detection units, a grating demodulator and a control end, wherein the detection units are connected in sequence and are arranged in a linear array; a strain self-compensation temperature and strain detection assembly in the detection unit comprises two flexible conductive metal tubes which are vertically and correspondingly arranged, the flexible conductive metal tubes are filled with heat insulation layers, a plurality of settlement deformation compensation gratings which are subjected to heat insulation protection are arranged along the axes of the flexible conductive metal tubes, and temperature and deformation induction gratings which are subjected to heat conduction protection are fixedly connected to the inner walls of the flexible conductive metal tubes. The inner wall of one conductive metal tube is fixedly connected with a magnetic strain induction grating subjected to heat insulation protection, the magnetic strain induction grating is fixedly connected with magnetic sheets, the inner wall of the other conductive metal tube is fixedly connected with the other magnetic sheet, and the magnetic strain induction grating is located between the two magnetic sheets; the resistance of ceramsite soil between the two conductive metal tubes is measured based on the Wheatstone bridge principle, and the water seepage condition is judged. The temperature and settlement deformation detection precision is high, the response speed is high, and the water seepage detection function is integrated.

Description

Technical Field

[0001] The present invention relates to the field of operation monitoring of a molten salt tank foundation for photothermal energy storage, and in particular to a self-compensating grating measurement device and method for multi-parameter measurement of a tank foundation. Background Art

[0002] As an efficient way to store thermal energy, molten salt thermal storage technology can provide high-temperature heat storage in fields such as solar thermal power generation, improve energy efficiency, and reduce dependence on traditional fossil energy. As a key component of molten salt thermal storage technology, the stable operation and intelligent monitoring of molten salt storage tanks are important parts of molten salt thermal storage technology. At present, the leakage of molten salt in the tank, water seepage in the foundation, deformation of the foundation material, and the resulting uneven settlement are the main problems for the stable operation of the tank. When these situations occur, the temperature parameters and deformation parameters of the foundation material often change significantly, so the measurement of the temperature and deformation parameters of the tank foundation is crucial.

[0003] Invention patent CN117948905A discloses an online monitoring method and device for large oil storage tanks. The device can only monitor the strain data when foundation settlement affects the deformation of the tank body, and cannot directly monitor the relevant changes in the foundation. It has a certain hysteresis and cannot provide early warning and prevent the risks brought by foundation settlement. In addition, it has no temperature compensation device and is easily affected by external temperature changes, and the measurement accuracy is limited.

[0004] Invention patent CN113819662A discloses a molten salt storage tank with a leak detection and thermal compensation device. The device detects whether the molten salt in the tank has leaked by setting multiple thermocouples for temperature measurement under the tank. However, due to cost constraints and the difficulty of installing a large number of thermocouples in the leakage monitoring base plate, and the impact on the foundation strength and heat dissipation, the number of measurement points that can be installed is very limited. A leak detection base plate can only evenly distribute a small number of thermocouples. For a base plate with a diameter of 40m and a bottom area of ​​1000m 2 For a molten salt tank, the average area that needs to be detected by a thermocouple is more than ten square meters, and the thermocouple can only measure the temperature of a specific point. Unless the leak point is just above the thermocouple, the thermocouple can detect the temperature change. Therefore, it is impossible to achieve good coverage of the basic temperature measurement of the entire molten salt tank. The method of relying solely on pre-buried thermocouple detection cannot achieve the ideal effect, and the measurement of thermocouples may be affected by environmental factors (such as humidity, pressure, electromagnetic interference, etc.), and the monitoring effect is not accurate and sensitive enough.

[0005] Generally speaking, there is still room for improvement in the accuracy, sensitivity, and real-time performance of existing settlement and temperature monitoring technologies. Foundation temperature monitoring usually relies on thermocouples or resistance thermometers. However, since it is very difficult to install these devices in the tank foundation and they may affect the structure and insulation performance, the number of pre-embedded thermocouples is relatively small in practical applications, resulting in an overly large monitoring range for a single thermocouple. In addition, temperature measurement is easily interfered by environmental factors, and the result stability is poor. The traditional thermocouple and thermal resistance technologies have low sensitivity and cannot quickly respond to minor molten salt leaks. The foundation material deformation monitoring technology usually relies on level instruments or total station instruments to directly measure the foundation settlement, that is, data is collected when the part above the ground surface settles. At this time, the foundation settlement has affected the tank deformation, showing hysteresis. Moreover, these devices require manual operation and are easily interfered by human factors and environmental factors, and the accuracy needs to be improved. In order to ensure the stable operation of the storage tank, it is urgent to develop more accurate and sensitive temperature and deformation monitoring technologies. In addition, there are relatively few monitoring technologies with high functional integration at present. If multi-parameter monitoring is to be achieved, various devices need to be continuously added, which is likely to cause additional damage to the foundation, and there is a lack of monitoring technology integrating multi-functional parameters. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention proposes a self-compensating grating measurement device and method for multi-parameter measurement of a storage tank foundation.

[0007] The specific technical solutions are as follows:

[0008] A self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation, comprising: a grating demodulator, a control end, and a plurality of detection units arranged in a linear array. Each detection unit includes a temperature and strain detection component with strain self-compensation and a Wheastone bridge ceramsite soil resistance detection component; the temperature and strain detection component with strain self-compensation is connected to the grating demodulator, and the grating demodulator is connected to the control end. The grating demodulator is used for demodulating signals, and the control end is used for performing deformation compensation and analysis on the demodulated data;

[0009] The strain self-compensated temperature and strain detection component includes: two conductive metal tubes arranged vertically corresponding to each other, a heat insulation layer, a temperature and deformation induction grating, a grating heat conduction protection layer, a plurality of settlement deformation compensation gratings, a grating heat insulation protection layer, a magnetic force strain induction grating, and two magnetic force sheets; the conductive metal tube is a flexible hollow structure filled with a heat insulation layer inside; a grating heat insulation protection layer is arranged on the outer periphery of the settlement deformation compensation grating, and the grating heat insulation protection layer is arranged in the heat insulation layer and uniformly arranged along the axis on the axis of the conductive metal tube; a flexible grating heat conduction protection layer is arranged outside the temperature and deformation induction grating and is fixedly connected to the inner wall of the conductive metal tube and arranged in the same vertical direction as the settlement deformation compensation grating; a flexible grating heat insulation protection layer is arranged outside the magnetic force strain induction grating and is fixedly connected to the inner wall of the first conductive metal tube close to the second conductive metal tube, a first magnetic force sheet is fixedly connected to the grating heat insulation protection layer, a second magnetic force sheet is fixedly connected to the inner wall of the second conductive metal tube close to the first conductive metal tube, the first magnetic force sheet and the second magnetic force sheet are arranged opposite to each other in the same vertical direction, and the magnetic force strain induction grating is located between the two magnetic force sheets;

[0010] The resistance of the ceramsite soil between the two conductive metal tubes is the resistance to be measured. The Wheatstone bridge ceramsite soil resistance detection component is used to measure the resistance to be measured based on the Wheatstone bridge principle, and the measured resistance value is input to the control terminal, and the control terminal judges the water seepage situation according to the resistance value.

[0011] Further, the Wheatstone bridge ceramsite soil resistance detection component includes a resistance to be measured, a precision resistance box, a first precision resistance, a second precision resistance, a DC regulated power supply, and a galvanometer connected in sequence; the bridge arm where the first precision resistance is located and the bridge arm where the second precision resistance is located are connected to node C, the bridge arm where the second precision resistance is located and the bridge arm where the resistance to be measured is located are connected to node D, the bridge arm where the resistance to be measured is located and the bridge arm where the precision resistance box is located are connected to node A, and the bridge arm where the precision resistance box is located and the bridge arm where the first precision resistance is located are connected to node B; the positive and negative poles of the DC regulated power supply are respectively connected to node B and node D to provide a DC regulated power supply; the two ends of the galvanometer are respectively connected to node A and node C to detect whether there is current passing through in this path.

[0012] Further, the precision resistance box is an adjustable precision resistance box arranged on the ground with an accuracy of 0.1Ω; the accuracies of the first precision resistance and the second precision resistance are also 0.1Ω.

[0013] Further, a plurality of detection units are arranged in a linear array. The arrangement method of the linear array is: a plurality of detection units are arranged in a circumferential array with the central axis of the high-temperature molten salt storage tank as the center, that is, evenly divided into multiple groups in the circumferential direction, and multiple detection units are evenly arranged in the radial direction in each group.

[0014] Further, the grating heat conduction protection layer arranged around the temperature and deformation induction grating and the grating heat insulation protection layer arranged around the magnetic force strain induction grating are both fixedly connected to the inner wall of the conductive metal tube through epoxy resin.

[0015] Further, there are two temperature and deformation induction gratings, which are located in the upper conductive metal tube. The temperature and deformation induction gratings are arranged at the topmost part of the inner wall of the conductive metal tube and are arranged in the same vertical direction as the settlement deformation compensation grating; in the lower conductive metal tube, the temperature and deformation induction gratings are arranged at the bottommost part of the inner wall of the conductive metal tube and are arranged in the same vertical direction as the settlement deformation compensation grating.

[0016] Further, the control end compensates for and analyzes the deformed data after demodulation. Specifically: the settlement deformation data collected by the settlement deformation compensation grating is used to compensate for the deformation of the temperature and deformation induction grating, so that after being compensated, it only shows the influence of temperature on the grating, and temperature data is obtained; the settlement deformation data collected by the settlement deformation compensation grating is used to compensate for the deformation of the magnetic force strain induction grating, so that after being compensated, it only shows the influence of the change in the distance between the two conductive metal tubes on the grating, and distance change data is obtained; by comparing and analyzing the settlement deformation data in the same linear direction, the settlement situation of the foundation in this linear direction is obtained, and then combined with the layout of multiple linear directions, the overall settlement situation of the foundation is obtained.

[0017] A self-compensating grating measurement method for multi-parameter measurement of a storage tank foundation, implemented according to the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation, includes the following steps:

[0018] S1: According to the requirements of the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation, prepare a temperature and strain detection component with strain self-compensation and a Wheatstone bridge ceramsite soil resistance detection component, complete the grating optical fiber connection and calibration inside the temperature and strain detection component with strain self-compensation, and ensure that the signal transmission is not interfered.

[0019] S2: Arrange the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation into the foundation. During the compaction process of the ceramsite soil, lay the conductive metal tubes equipped with three gratings at the corresponding planned positions in the ceramsite soil, and ensure that the burial depth and position can cover the key temperature and strain measurement points; use jumpers to connect the temperature and deformation induction grating, the settlement deformation compensation grating, and the magnetic force strain induction grating to the grating demodulator respectively, and connect the grating demodulator to the control end; place the grating demodulator and the control end on the upper surface of the foundation.

[0020] S3: Start the control end and the Wheatstone bridge ceramsite soil resistance detection component, ensure that the bridge works stably, and start detection.

[0021] S4: The grating demodulator emits an optical signal, and simultaneously receives and demodulates the optical signals reflected from the temperature and deformation sensing grating, the settlement deformation compensation grating, and the magnetic strain sensing grating; the demodulated data is transmitted to the control end for real-time processing and analysis, and deformation compensation is performed to realize the detection of the temperature and settlement deformation of the foundation material.

[0022] Meanwhile, the Wheatstone bridge ceramsite soil resistance detection component measures the resistance value of the resistance to be measured, and evaluates the seepage intensity of the foundation based on the change data of the resistance value, so as to infer the permeability of the soil.

[0023] Further, in the S4, after the grating demodulator analyzes the optical signal, the control end performs deformation compensation, specifically as follows:

[0024] Subtract the central wavelength drift amount actually detected by the temperature and deformation sensing grating from the central wavelength drift amount Δλ of the grating affected only by settlement deformation BS to obtain the central wavelength drift amount Δλ of the grating affected only by temperature BT , and further obtain the temperature after settlement deformation compensation;

[0025] Subtract the central wavelength drift amount actually detected by the magnetic strain sensing grating from Δλ BS to obtain the central wavelength drift amount Δλ of the grating caused only by the change in magnetic force BW , so as to reflect the grating strain situation caused by the change in magnetic force, and further obtain the change in the distance between the two conductive metal tubes.

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) The present invention has the ability of rapid response and good real-time performance for the detection of temperature and deformation: adopting the fiber Bragg grating sensing technology, it has high sensitivity, can quickly collect and transmit information, so as to realize real-time detection.

[0028] (2) The parameter detection of the present invention is accurate: adopting the embedded detection technology, directly detecting the changes of various parameters of the foundation, it has higher accuracy compared with the detection of the settlement change of the above-ground part.

[0029] (3) The present invention has a wide detection range and accurate settlement analysis: the detection units are arranged in a distributed linear array, and the deformation data generated at different positions in the same linear direction are analyzed, and the settlement situation in this linear direction can be accurately analyzed.

[0030] (4) The present invention has a high integration level and multiple detection functions: The device is relatively small in size and is protected by a conductive metal tube on the outside. It is buried during the compaction process of ceramsite soil, with a high survival rate and little impact on the foundation. Through the installation and compensation methods, the detection device has a high functional integration level and can detect temperature, settlement deformation, and the resistance of ceramsite soil, enabling the detection of multiple conditions of the foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. is a schematic structural diagram of one unit of the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation in an embodiment of the present invention.

[0032] Figure 2 FIG. is a cross-sectional view of one of the temperature and strain detection components with strain self-compensation in an embodiment of the present invention.

[0033] Figure 3 FIG. is a schematic structural diagram of the Wheatstone bridge ceramsite soil resistance detection component in an embodiment of the present invention.

[0034] Figure 4 FIG. is a top view of the array arrangement of multiple units of the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation in the foundation in an embodiment of the present invention.

[0035] Figure 5 FIG. is a front view of the arrangement of the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation in the foundation in an embodiment of the present invention.

[0036] In the figure, the temperature and strain detection component 101 with strain self-compensation, conductive metal tube 101-1, temperature and deformation induction grating 101-2, heat insulation layer 101-3, grating heat conduction protection layer 101-4, settlement deformation compensation grating 101-5, grating heat insulation protection layer 101-6, magnetic force strain induction grating 101-7, epoxy resin 101-8, magnetic force sheet 101-9; Wheatstone bridge ceramsite soil resistance detection component 102, precision resistance box 102-1, first precision resistance 102-2, DC regulated power supply 102-3, second precision resistance 102-4, galvanometer 102-5, resistance to be measured 102-6; information acquisition and analysis component 103, grating demodulator 103-1, control end 103-2, jumper 103-3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The present invention will be described in detail below according to the drawings and preferred embodiments. The purpose and effects of the present invention will become more apparent. The following further details the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] As Figure 1As shown in the figure, a self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation includes: a plurality of detection units arranged in an array and an information acquisition and analysis component 103. Each detection unit includes a temperature and strain detection component 101 with strain self-compensation and a Wheatstone bridge ceramsite soil resistance detection component 102. The temperature and strain detection component 101 with strain self-compensation is buried into the ceramsite soil layer of the foundation according to the specified position, so as to directly sense the temperature change and settlement change in the foundation. The grating signal detected by this detection component is uniformly transmitted to the information acquisition and analysis system 103 through an optical fiber, and the system performs signal demodulation, compensation, and analysis to make a judgment on the overall temperature distribution and deformation and settlement conditions. The Wheatstone bridge ceramsite soil resistance detection component 102 is connected to the two conductive metal tubes 101-1 of the temperature and strain detection component 101 with strain self-compensation through wires, and then detects the resistance of the ceramsite soil between the two conductive metal tubes 101-1, so as to judge whether the ceramsite soil layer has water seepage.

[0039] As Figure 2 shown in the figure, the temperature and strain detection component 101 with strain self-compensation includes: conductive metal tubes 101-1, a temperature and deformation induction grating 101-2, a heat insulation layer 101-3, a grating heat conduction protection layer 101-4, a settlement deformation compensation grating 101-5, a grating heat insulation protection layer 101-6, a magnetic force strain induction grating 101-7, an epoxy resin 101-8, and a magnetic sheet 101-9.

[0040] There are two conductive metal tubes 101-1, both of which are hollow cylinders and are arranged corresponding to each other vertically. There is a certain thickness of ceramsite soil between the two conductive metal tubes 101-1. The conductive metal tube 101-1 serves as a protection device for burying the grating optical fiber into the ceramsite soil layer of the foundation (improving the survival rate of the grating), and its interior is filled with a heat insulation layer 101-3 with good heat insulation effect. While ensuring the strength, the conductive metal tube 101-1 should have good plasticity and ductility so as to be able to undergo large deformations without breaking, ensuring good deformation response. There are multiple settlement deformation compensation gratings 101-5, and each is arranged with a grating heat insulation protection layer 101-6 on its outer periphery, which plays a role in protecting the settlement deformation compensation grating 101-5 and at the same time avoids the influence of temperature on the settlement deformation compensation grating 101-5. The grating heat insulation protection layer 101-6 is coaxially arranged at the center of the conductive metal tube 101-1 and is uniformly arranged along the axial direction. The grating heat insulation protection layer 101-6 is wrapped by the heat insulation layer 101-3. While the heat insulation layer 101-3 plays a role in limiting and supporting the grating heat insulation protection layer 101-6, it also further avoids the influence of temperature on the settlement deformation compensation grating 101-5, making it only affected by settlement deformation, so as to facilitate later deformation compensation.

[0041] The temperature and deformation induction grating 101-2 is externally wrapped with a grating heat conduction protection layer 101-4. The grating heat conduction protection layer 101-4 has good heat conductivity, flexibility and sealing performance, plays a role in protecting the temperature and deformation induction grating 101-2, and enables the temperature and deformation induction grating 101-2 to better receive the temperature of the ceramsite soil layer transmitted from the conductive metal pipe 101-1. This setting realizes that the temperature and deformation induction grating 101-2 is jointly affected by temperature and deformation. The grating heat conduction protection layer 101-4 is fixedly connected to the inner wall of the conductive metal pipe 101-1 through epoxy resin 101-8, ensuring that the deformation of the temperature and deformation induction grating 101-2 and the conductive metal pipe 101-1 has a good response and improving the sensitivity of detecting deformation. Among them, in the upper conductive metal pipe 101-1, the temperature and deformation induction grating 101-2 is arranged at the topmost part of the inner wall of the conductive metal pipe 101-1 and is arranged in the same vertical direction as the settlement deformation compensation grating 101-5; in the lower conductive metal pipe 101-1, the temperature and deformation induction grating 101-2 is arranged at the bottommost part of the inner wall of the conductive metal pipe 101-1 and is arranged in the same vertical direction as the settlement deformation compensation grating 101-5.

[0042] The magnetic force strain induction grating 101-7 is externally wrapped with a grating heat insulation protection layer 101-6. The grating heat insulation protection layer 101-6 is fixedly connected to the inner wall of the conductive metal pipe 101-1 through epoxy resin 101-8. The grating heat insulation protection layer 101-6 has good heat insulation performance and flexibility, plays a role in protecting the magnetic force strain induction grating 101-7, ensures that the deformation of the magnetic force strain induction grating 101-7 and the conductive metal pipe 101-1 has a good response, and at the same time avoids the influence of temperature on the magnetic force strain induction grating 101-7. In this embodiment, a magnetic force strain induction grating 101-7 is placed closely against the topmost part of the inner wall of the lower conductive metal pipe 101-1. A magnetic force sheet 101-9 with strong magnetism is fixedly connected to the center of the lower surface of the magnetic force strain induction grating 101-7. Another magnetic force sheet 101-9 is placed closely against the bottommost part inside the upper conductive metal pipe 101-1, and the two magnetic force sheets 101-9 are located in the same vertical direction. As another embodiment, the magnetic force strain induction grating 101-7 is closely arranged at the bottommost part inside the upper conductive metal pipe 101-1, and one magnetic force sheet 101-9 is fixedly connected to the center of the upper surface of the magnetic force strain induction grating 101-7. For the different settings of the two embodiments, it only needs to satisfy that the magnetic force strain induction grating 101-7 is located between the two magnetic force sheets 101-9. The principle of the magnetic force strain induction grating 101-7 for detection is that the magnetic force strain induction grating 101-7 is affected by the magnetic force sheet 101-9, converts the distance change between the two magnetic force sheets 101-9 into a magnetic force change, and the magnetic force acts on the middle part of the magnetic force strain induction grating 101-7 to cause strain, so as to reflect the local settlement situation.

[0043] Since the magnetic strain induction grating 101-7 is affected by both magnetic force and settlement deformation, and the temperature and deformation induction grating 101-2 is affected by both temperature and settlement deformation, when the subsequent information acquisition and analysis component 103 processes, the settlement deformation compensation grating 101-5 compensates for the settlement deformation of both, so as to accurately measure the temperature and the change in the distance between the two conductive metal tubes 101-1.

[0044] As Figure 3 shown, the Wheatstone bridge ceramsite soil resistance detection component 102 includes: a precision resistance box 102-1, a first precision resistance 102-2, a DC regulated power supply 102-3, a second precision resistance 102-4, a galvanometer 102-5, and a resistance to be measured 102-6.

[0045] The resistance to be measured 102-6 is the ceramsite soil between the two conductive metal tubes 101-1 of the same strain self-compensating temperature and strain detection component 101. The resistance to be measured 102-6 (R x ) is sequentially connected to the precision resistance box 102-1 (R0), the first precision resistance 102-2 (R1), and the second precision resistance 102-4 (R2), jointly constituting the bridge arms of the Wheatstone bridge. Among them, both the first precision resistance 102-2 and the second precision resistance 102-4 are precision resistances with an accuracy of 0.1Ω, serving as the ratio arms of the Wheatstone bridge; the precision resistance box 102-1 is an adjustable precision resistance box (which can be manually adjusted during subsequent detection), with a relatively large resistance value and an accuracy of 0.1Ω.

[0046] The bridge arm where the first precision resistance 102-2 is located is connected to the bridge arm where the second precision resistance 102-4 is located at node C, the bridge arm where the second precision resistance 102-4 is located is connected to the bridge arm where the resistance to be measured 102-6 is located at node D, the bridge arm where the resistance to be measured 102-6 is located is connected to the bridge arm where the precision resistance box 102-1 is located at node A, and the bridge arm where the precision resistance box 102-1 is located is connected to the bridge arm where the first precision resistance 102-2 is located at node B. The positive and negative poles of the DC regulated power supply 102-3 are respectively connected to node B and node D to provide a DC regulated power supply; the two ends of the galvanometer 102-5 are respectively connected to node A and node C to detect whether there is current passing through this path.

[0047] The Wheatstone bridge ceramsite soil resistance detection component 102 can be arranged on the ground to protect each resistance, improve the service life, and at the same time facilitate the adjustment of the precision resistance box 102-1 and the replacement of the resistance. The principle by which the Wheatstone bridge ceramsite soil resistance detection component 102 determines whether water seepage occurs in the ceramsite soil layer is as follows:

[0048] Ceramsite soil is a lightweight and porous engineering material, which is formed by mixing ceramsite and soil in a certain proportion, and has the characteristics of light weight and good water permeability; there are interconnected channels between ceramsite, water and air pores, and electrons are transmitted therein to achieve conductivity. Therefore, the change in the resistance of ceramsite soil reflects the dryness of the ceramsite soil material, and can be used as a detection index for foundation seepage. The drier it is, the greater the resistance. The precision resistance box 102-1 takes the maximum value when the bridge is unbalanced to prevent excessive current from damaging the galvanometer 102-5. When the DC regulated power supply 102-3 of the Wheatstone bridge is turned on, when the bridge is unbalanced, there is current passing through the galvanometer 102-5 on the "bridge", and the galvanometer 102-5 deflects; by adjusting the resistance of each arm, the potential between points A and C can be made equal, and there is no current on the "bridge", that is, the galvanometer 102-5 does not deflect. At this time, the bridge is said to be in a balanced state. When the bridge is in a balanced state, R0R2 = R1R x , this formula is the balance condition of the bridge, that is, the product of the resistances of the opposite arms of the bridge is equal. According to the balance condition of the bridge, if the resistance values of any three of the arms are known, the resistance value of the other bridge arm can be calculated. Therefore, the calculation formula for measuring resistance with a bridge is R x = R2 / R1·R0 = KR0, where K is the ratio arm of the bridge. In the experiment, R1 = R2 is often used, and R x is the arm to be measured, and R0 is used as the standard resistance for comparison. In this embodiment, the ceramsite soil is designed as one of the bridge arms of the Wheatstone bridge, that is, the arm to be measured R x . After power on, the resistance of the precision resistance box 102-1 is changed according to the deflection of the galvanometer 102-5. When the galvanometer 102-5 does not deflect, the corresponding resistance R x is calculated, and the magnitude of this resistance also reflects the intensity of the seepage volume.

[0049] As Figure 4 shown, the self-compensated grating measuring device for multi-parameter measurement of the storage tank foundation is arranged in the foundation under the high-temperature molten salt storage tank. Each detection unit is on the same horizontal plane and is arranged in a linear array; each detection unit is connected to the grating demodulator 16 through a jumper 18. By analyzing the settlement deformation data generated at different positions in the same linear direction, the settlement of the foundation in this linear direction can be accurately analyzed. In this embodiment, the array arrangement method is: the detection units are centered on the axis of the high-temperature molten salt storage tank, radiate around and are arranged in a circumferential array, that is, evenly divided into multiple groups in the circumferential direction, and multiple detection units are evenly arranged in each group along the radial direction.

[0050] As Figure 4 and Figure 5As shown in the figure, the information acquisition and analysis component 103 includes: a grating demodulator 103-1, a control terminal 103-2, and a jumper wire 103-3. The pigtails of the temperature and deformation induction grating 101-2, the settlement deformation compensation grating 101-5, and the magnetic strain induction grating 101-7 are respectively connected to the grating demodulator 103-1 through the jumper wire 103-3, and the optical signals detected by the three gratings are transmitted to the grating demodulator 103-1 in real time; the grating demodulator 103-1 is connected to the control terminal 103-2, and the data parsed by the grating demodulator 103-1 is transmitted to the control terminal 103-2. The grating demodulator 103-1 is used to parse the optical signals transmitted by the jumper wire 103-3 so as to generate the required data, and the measured variables can be analyzed by observing the wavelength changes of the three gratings. The temperature and strain monitoring device 101 with strain self-compensation is arranged in sequence according to the linear arrangement mode, and the optical signals are transmitted to the grating demodulator 103-1 through the jumper wire 103-3, and then the grating demodulator 103-1 transmits the generated data to the control terminal 103-2 for analysis. The control terminal 103-2 first performs relevant data compensation work, that is, the settlement deformation data collected by the settlement deformation compensation grating 101-5 is used to perform deformation compensation on the temperature and deformation induction grating 101-2, so that after compensation, it only shows the influence of temperature on the grating, so as to achieve the effect of temperature measurement and obtain more accurate temperature data; the settlement deformation data collected by the settlement deformation compensation grating 101-5 is used to perform deformation compensation on the magnetic strain induction grating 101-7, so that after compensation, it only shows the influence of the spacing change on the grating, so as to obtain more accurate spacing change data, and then reflect the settlement situation. The control terminal 103-2 obtains the settlement situation of the foundation in this linear direction by comparing and analyzing the deformation data in the same linear direction, and further obtains the overall settlement situation of the foundation by combining the arrangements in multiple linear directions.

[0051] Based on the above self-compensating grating measuring device for multi-parameter measurement of storage tank foundation, an embodiment of the present invention also proposes a self-compensating grating measuring method for multi-parameter measurement of storage tank foundation, including the following steps:

[0052] S1: According to the requirements of the above self-compensating grating measuring device for multi-parameter measurement of storage tank foundation, prefabricate the temperature and strain detection component 101 with strain self-compensation and the Wheatstone bridge ceramsite soil resistance detection component 102, and ensure that all kinds of grating sensors work stably. The temperature and deformation induction grating 101-2, the settlement deformation compensation grating 101-5, and the magnetic strain induction grating 101-7 are respectively and precisely installed in the conductive metal tube 101-1 according to the predetermined measurement positions, and the grating optical fiber connection and calibration inside the temperature and strain detection component 101 with strain self-compensation are completed to ensure that the optical fiber signal can be stably transmitted without interference and reach the grating demodulator 103-1 smoothly, which is convenient for subsequent data transmission and analysis.

[0053] S2: Place the device into the foundation. During the compaction process of the ceramsite soil, lay the conductive metal tubes 101-1 equipped with three gratings accurately at the corresponding planned positions in the ceramsite soil. Pay special attention to the burial depth and position of the conductive metal tubes 101-1 to ensure that they can cover the key temperature and strain measurement points; use the jumper 103-3 to connect the temperature and deformation induction grating 101-2, the settlement deformation compensation grating 101-5, and the magnetic strain induction grating 101-7 to the grating demodulator 103-1 respectively, and connect the grating demodulator 103-1 to the control terminal 103-2; place the grating demodulator 103-1 and the control terminal 103-2 on the upper surface of the foundation.

[0054] S3: Start the control terminal 103-2 and ensure that the power supply is normal; start the Wheatstone bridge ceramsite soil resistance detection component 102 to ensure that the bridge works stably and start the detection.

[0055] S4: The grating demodulator 103-1 emits an optical signal, and at the same time receives and demodulates the optical signal reflected from the fiber grating. The demodulated data will be transmitted through the optical fiber to the control terminal 103-2 for real-time processing and analysis, and finally achieve the accurate detection of the temperature and settlement deformation of the foundation material.

[0056] At the same time, observe the change of the galvanometer 102-5. When the galvanometer 102-5 deflects, adjust the resistance value of the precision resistance box 102-1 in time to calibrate the measurement system. Calculate the resistance value of the ceramsite soil according to the principle of the Wheatstone bridge, evaluate its water seepage intensity based on the changing data, and infer the soil permeability according to the change of the resistance value.

[0057] Furthermore, in S4, the grating demodulator 103-1 analyzes the optical signals returned by the temperature and deformation induction grating 101-2, the settlement deformation compensation grating 101-5, and the magnetic strain induction grating 101-7. The principle is as follows:

[0058] When the grating is only affected by temperature, the change in the drift amount of the grating center wavelength is mainly reflected in two aspects: the thermo-optic effect causes the refractive index to change, and the thermal expansion effect causes the grating period to change. These changes will cause the drift of the reflected wavelength. By detecting this wavelength change, the magnitude of the temperature change can be deduced; at this time, the drift amount Δλ of the grating center wavelength BT is expressed as follows:

[0059] Δλ BT =λ BT (ζ + α)·ΔT

[0060] In the formula, λ BTis the Bragg wavelength of the temperature and deformation sensing grating 101-2 when it is only affected by temperature, which is an unknown quantity; α is the thermal expansion coefficient of the optical fiber, ζ is the thermo-optic coefficient of the optical fiber, and ΔT is the temperature change.

[0061] In practical applications, the temperature and deformation sensing grating 101-2 is affected by both settlement deformation and temperature. The settlement compensation needs to be carried out through the control end 103-2 to obtain λ BT .

[0062] When the grating is only affected by settlement deformation, the change in the central wavelength drift of the grating is mainly reflected in two aspects: the elasto-optic effect causes the refractive index to change, and the settlement deformation causes the grating period to change. At this time, the central wavelength drift of the grating Δλ BS has the following expression:

[0063] Δλ BS = λ BS (1 - P)ε

[0064] In the formula, λ BS is the Bragg wavelength of the settlement deformation compensation grating 101-5; P is the elasto-optic coefficient of the optical fiber, and ε is the change in the grating period caused by the deformation of the optical fiber.

[0065] In this case, the central wavelength drift of the grating Δλ BS reflects the total effect of the change in the optical fiber grating period and refractive index caused by the deformation.

[0066] When the grating is only affected by the deformation caused by magnetic force, the change in the central wavelength drift of the grating is mainly reflected in two aspects: the elasto-optic effect causes the refractive index to change, and the deformation caused by magnetic force causes the grating period to change. At this time, the central wavelength drift of the grating Δλ BW has the following expression:

[0067] Δλ BW = λ BW (1 - P)ε

[0068] In the formula, Δλ BW is the Bragg wavelength when the magnetic force strain sensing grating 101-7 is only affected by the deformation caused by magnetic force, which is an unknown quantity.

[0069] In practical applications, the magnetic force strain sensing grating 101-7 is affected by both settlement deformation and the deformation caused by magnetic force. The settlement deformation compensation needs to be carried out through the control end 103-2 to obtain Δλ BW .

[0070] S4: The grating demodulator 103-1 transmits the analyzed data to the control end 103-2, and the control end 103-2 performs deformation compensation. The specific operations are as follows:

[0071] The control terminal 103-2 performs settlement deformation compensation on the detection results of the temperature and deformation induction grating 101-2, that is, subtracts Δλ from the center wavelength drift obtained by actual detection of the temperature and deformation induction grating 101-2 to obtain the center wavelength drift of the grating affected only by temperature, Δλ BS BT and then calculate the corresponding temperature after settlement deformation compensation. Similarly, perform settlement deformation compensation on the detection results of the magnetic strain induction grating 101-7, subtract Δλ from the center wavelength drift obtained by actual detection of the magnetic strain induction grating 101-7 to obtain the center wavelength drift of the grating caused only by the change in magnetic force, Δλ BS BW so as to reflect the grating strain situation caused by the magnetic force, and then obtain the change in the distance between the two conductive metal tubes 101-1. Finally, combine the deformation change values of each linearly arranged group to determine the overall settlement and local settlement of the foundation

[0072] Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not used to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention​​

Claims

1. A self-compensating grating measuring device for multi-parameter measurement of storage tank foundations, characterized in that, Comprising: A grating demodulator, a control terminal, and a plurality of detection units arranged in a linear array. Each detection unit includes a temperature and strain detection component with strain self-compensation and a ceramsite soil resistance detection component of a Wheatstone bridge; the temperature and strain detection component with strain self-compensation is connected to the grating demodulator, and the grating demodulator is connected to the control terminal. The grating demodulator is used for demodulating signals, and the control terminal is used for performing deformation compensation and analysis on the demodulated data. The temperature and strain detection component with strain self-compensation includes: two conductive metal tubes arranged vertically corresponding to each other, a heat insulation layer, a temperature and deformation induction grating, a grating heat conduction protection layer, a plurality of settlement deformation compensation gratings, a grating heat insulation protection layer, a magnetic force strain induction grating, and two magnetic force pieces; the conductive metal tubes are flexible hollow structures filled with a heat insulation layer inside; a grating heat insulation protection layer is arranged on the outer periphery of the settlement deformation compensation grating, and the grating heat insulation protection layer is arranged in the heat insulation layer and is uniformly arranged along the axis on the axis of the conductive metal tube; a flexible grating heat conduction protection layer is arranged outside the temperature and deformation induction grating and is fixedly connected to the inner wall of the conductive metal tube and is arranged in the same vertical direction as the settlement deformation compensation grating; a flexible grating heat insulation protection layer is arranged outside the magnetic force strain induction grating and is fixedly connected to the inner wall of the first conductive metal tube close to the second conductive metal tube. A first magnetic force piece is fixedly connected to the grating heat insulation protection layer, and a second magnetic force piece is fixedly connected to the inner wall of the second conductive metal tube close to the first conductive metal tube. The first magnetic force piece and the second magnetic force piece are arranged opposite to each other in the same vertical direction, and the magnetic force strain induction grating is located between the two magnetic force pieces. The resistance of the ceramsite soil between the two conductive metal tubes is the resistance to be measured. The ceramsite soil resistance detection component of the Wheatstone bridge is used for measuring the resistance to be measured based on the Wheatstone bridge principle, and the measured resistance value is input to the control terminal, and the control terminal judges the water seepage situation according to the resistance value.

2. The self-compensating grating measuring device for multi-parameter measurement of storage tank foundation according to claim 1, wherein The ceramsite soil resistance detection component of the Wheatstone bridge includes a resistance to be measured, a precision resistance box, a first precision resistance, a second precision resistance, which are connected in sequence, as well as a DC regulated power supply and a galvanometer; the bridge arm where the first precision resistance is located and the bridge arm where the second precision resistance is located are connected at node C, the bridge arm where the second precision resistance is located and the bridge arm where the resistance to be measured is located are connected at node D, the bridge arm where the resistance to be measured is located and the bridge arm where the precision resistance box is located are connected at node A, and the bridge arm where the precision resistance box is located and the bridge arm where the first precision resistance is located are connected at node B; the positive and negative poles of the DC regulated power supply are respectively connected to node B and node D for providing a DC regulated power supply; the two ends of the galvanometer are respectively connected to node A and node C for detecting whether there is current passing through in this path.

3. The self-compensated grating measuring device for multi-parameter measurement of a storage tank foundation according to claim 2, wherein, The precision resistance box is an adjustable precision resistance box, arranged on the ground, with a precision of 0.1Ω; the precision of the first precision resistance and the second precision resistance is also 0.1Ω.

4. The self-compensating grating measuring device for multi-parameter measurement of storage tank foundation according to claim 1, wherein, A plurality of detection units arranged in a linear array. The arrangement method of the linear array is: a plurality of detection units are centered on the central axis of the high-temperature molten salt storage tank and are arranged in a circumferential array, that is, evenly divided into multiple groups in the circumferential direction, and multiple detection units are evenly arranged in the radial direction in each group.

5. The self-compensated grating measuring device for multi-parameter measurement of storage tank foundation according to claim 1, characterized in that, The grating heat conduction protection layer arranged on the periphery of the temperature and deformation induction grating and the grating heat insulation protection layer arranged on the periphery of the magnetic force strain induction grating are both fixedly connected to the inner wall of the conductive metal pipe through epoxy resin.

6. The self-compensating grating measuring device for multi-parameter measurement of storage tank foundation according to claim 1, wherein, There are two temperature and deformation induction gratings, which are located in the upper conductive metal pipe. The temperature and deformation induction gratings are arranged at the topmost part of the inner wall of the conductive metal pipe and are arranged in the same vertical direction as the settlement deformation compensation grating; in the lower conductive metal pipe, the temperature and deformation induction gratings are arranged at the bottommost part of the inner wall of the conductive metal pipe and are arranged in the same vertical direction as the settlement deformation compensation grating.

7. The self-compensating grating measuring device for multi-parameter measurement of a storage tank foundation according to claim 1, characterized in that, The control end compensates and analyzes the demodulated data. Specifically: through the settlement deformation data collected by the settlement deformation compensation grating, the temperature and deformation induction grating is compensated for deformation, so that after compensation, it only shows the influence of temperature on the grating, and temperature data is obtained; through the settlement deformation data collected by the settlement deformation compensation grating, the magnetic force strain induction grating is compensated for deformation, so that after compensation, it only shows the influence of the distance change between the two conductive metal pipes on the grating, and the distance change data is obtained; by comparing and analyzing the settlement deformation data in the same linear direction, the settlement condition of the foundation in this linear direction is obtained, and then combined with the arrangement of multiple linear directions, the overall settlement condition of the foundation is obtained.

8. A self-compensating grating measurement method for multi-parameter measurement of a storage tank foundation, implemented according to the self-compensating grating measurement device for multi-parameter measurement of a storage tank foundation described in any one of claims 1-8, characterized in that, It includes the following steps: S1: According to the requirements of the self-compensated grating measuring device for multi-parameter measurement of the storage tank foundation, prepare the temperature and strain detection component with strain self-compensation and the Whistler bridge ceramsite soil resistance detection component, complete the grating optical fiber connection and calibration inside the temperature and strain detection component with strain self-compensation, and ensure that the signal transmission is not interfered. S2: Arrange the self-compensated grating measuring device for multi-parameter measurement of the storage tank foundation into the foundation. During the compaction process of the ceramsite soil, lay the conductive metal pipes equipped with three gratings at the corresponding planned positions in the ceramsite soil, and ensure that the burial depth and position can cover the key temperature and strain measurement points; use jumpers to connect the temperature and deformation induction grating, the settlement deformation compensation grating, and the magnetic force strain induction grating to the grating demodulator respectively, and connect the grating demodulator to the control end; the grating demodulator and the control end are placed on the upper surface of the foundation. S3: Start the control end and the Whistler bridge ceramsite soil resistance detection component to ensure the stable operation of the bridge and start detection. S4: The grating demodulator emits an optical signal, and at the same time receives and demodulates the optical signals reflected from the temperature and deformation induction grating, the settlement deformation compensation grating, and the magnetic force strain induction grating; the demodulated data is transmitted to the control end for real-time processing and analysis, and deformation compensation is performed to realize the detection of the temperature and settlement deformation of the foundation material. At the same time, the Whistler bridge ceramsite soil resistance detection component measures the resistance value of the measured resistance, and evaluates the seepage intensity of the foundation based on the change data of the resistance value, so as to infer the permeability of the soil.

9. The self-compensating grating measurement method for multi-parameter measurement of a storage tank foundation according to claim 8, characterized in that, In S4, after the grating demodulator analyzes the optical signal, the control end performs deformation compensation, specifically as follows: Subtract the center wavelength drift amount actually detected by the temperature and deformation sensing grating from the center wavelength drift amount Δλ of the grating only affected by settlement deformation BS to obtain the center wavelength drift amount Δλ of the grating only affected by temperature BT , and then obtain the temperature after settlement deformation compensation; Subtract the center wavelength drift amount actually detected by the magnetic strain induction grating from Δλ BS to obtain the center wavelength drift amount Δλ of the grating caused only by the magnetic force change BW , so as to reflect the grating strain situation caused by the magnetic force change, and further obtain the spacing change between the two conductive metal tubes.

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