An effective stress static cone penetrometer based on fiber bragg grating

Abstract

The application discloses an effective stress static sounding instrument based on a fiber Bragg grating, belongs to the technical field of in-situ testing of geotechnical engineering, and comprises a probe, a probe rod and an integrated fiber sensing assembly distributed in the probe and the probe rod, wherein the probe and the probe rod are connected with each other; the probe comprises a cone head and a cone head deformation column; the probe rod comprises an effective stress ring column, a inclinometer ring column, a sidewall friction cylinder, a demodulation ring column, a grating demodulation module arranged in a cavity of the demodulation ring column, a damping cylinder and a built-in optical fiber channel; the integrated fiber sensing assembly comprises a fiber cone tip resistance sensing module, a fiber sidewall friction resistance sensing module, a fiber inclinometer sensing module and a fiber effective stress sensing module, and is connected to the grating demodulation module based on the built-in optical fiber channel. The application unifies the data acquisition and analysis system of the effective stress sounding instrument through the integrated fiber sensing assembly, and improves the data precision and the exploration efficiency.

Description

Technical Field

[0001] This invention relates to the field of in-situ testing technology in geotechnical engineering, and in particular to an effective stress static cone penetrometer based on a fiber Bragg grating. Background Technology

[0002] In the field of geotechnical engineering exploration and design, accurately obtaining the physical and mechanical properties of soil is a prerequisite for ensuring the safety and economy of engineering projects. Traditional borehole sampling methods are affected by factors such as severe soil disturbance, lengthy test cycles, and large data fluctuations, making it difficult to truly reflect the in-situ characteristics of the soil. Cone Penetration Test (CPT) is efficient, fast, causes minimal disturbance, and provides continuous data. It can record changes in cone tip resistance and sidewall friction during the penetration process in real time, intuitively showing the soil structure, strength, and deformation characteristics, and is widely used in geological exploration. Currently, the Cone Penetration Test with Pore Pressure Measurement (CPTU), which integrates a pore water pressure sensor, can simultaneously measure changes in pore water pressure in the soil, providing a reference for the analysis of soil strength and deformation characteristics.

[0003] Effective stress is a key factor affecting soil deformation and strength properties, and accurate in-situ measurement of effective stress is crucial for safety assessment in engineering design. However, although conventional CPTU systems are equipped with various types of sensors, they still require indirect calculation to derive effective stress by subtracting pore water pressure from total stress, making it difficult to directly obtain the true parameters. Furthermore, traditional strain gauge sensors suffer from significant measurement errors and poor resistance to electromagnetic interference.

[0004] Fiber Bragg gratings (FBGs), as a novel sensing technology, possess high precision, wide measurement range, and strong anti-interference characteristics, and have been successfully applied in fields such as slope stability monitoring and tunnel deformation control. Although some studies have attempted to combine FBGs with static cone penetration tests (CPTs), most have adopted indirect measurement methods using deformed beam strain. Therefore, there is an urgent need to develop a high-precision static cone penetration test instrument based on FBGs to measure cone tip resistance, side friction resistance, and effective stress during static cone penetration testing, thereby overcoming existing technological bottlenecks and improving the level of geotechnical engineering safety assessment.

[0005] Therefore, existing technologies still need to be improved and enhanced. Summary of the Invention

[0006] To address the aforementioned deficiencies in existing technologies, this invention provides an effective stress static cone penetrometer based on a fiber Bragg grating. This aims to solve the problems of existing technologies lacking a direct measurement instrument for the effective stress of soil in in-situ testing based on a fiber Bragg grating, as well as the significant measurement errors and weak electromagnetic interference resistance of current static cone penetrometers.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] An effective stress static cone penetrometer based on a fiber Bragg grating is provided. The effective stress static cone penetrometer based on a fiber Bragg grating includes a probe, a probe rod, and an integrated fiber optic sensing component distributed in the probe and the probe rod. The probe and the probe rod are interconnected.

[0009] The probe includes a cone head and a cone head deformation column;

[0010] The probe rod includes an effective stress ring column, a tilt measuring ring column, a sidewall friction cylinder, a demodulation ring column, a grating demodulation module disposed in the cavity of the demodulation ring column, a damping cylinder, and a built-in optical fiber path;

[0011] The integrated fiber optic sensing assembly includes a fiber optic tip resistance sensing module, a fiber optic sidewall friction sensing module, a fiber optic inclinometer module, and a fiber optic effective stress sensing module. It is connected to the grating demodulation module via the built-in fiber optic path. The fiber optic tip resistance sensing module is located in the probe, the fiber optic inclinometer module is located at the center of the inclinometer ring, the fiber optic sidewall friction sensing module is located above the inner side of the sidewall friction cylinder, and the fiber optic effective stress sensing module is located outside the effective stress ring.

[0012] In one implementation, the fiber optic taper resistance sensing module includes a first rectangular base, a first fiber optic strain sensor, a first fiber optic temperature sensor, a first deformable thin plate, and a first connecting member.

[0013] The first deformable thin plate is a rectangular steel plate, which will deform when subjected to the action of the conical deformable column;

[0014] The first fiber optic strain sensor is arranged at the center of the inner wall of the first deformable thin plate to measure the deformation at the center of the thin plate.

[0015] The first fiber optic temperature sensor is arranged in the cavity of the first rectangular base to measure the temperature change during the penetration process.

[0016] The first rectangular base is used to fix the optical fiber cable, the first optical fiber strain sensor and the first optical fiber temperature sensor in the optical fiber taper resistance sensing module;

[0017] The first connecting member is used to connect the first rectangular base to the first deformable thin plate.

[0018] In one implementation, the first deformable thin plate is a rectangular thin plate, and the first fiber optic strain sensor is arranged at the center of the inner wall of the rectangular thin plate. When the effective stress of the soil is measured by the effective stress static cone penetrometer based on the fiber Bragg grating, the resistance experienced by the probe is calculated based on the cone tip resistance formula, which is:

[0019] ;

[0020] in, For cone tip resistance, D Let be the bending stiffness of the first deformed thin plate. Let be the thickness of the first deformed thin plate. a and b These are the length and width of the first deformed thin plate, respectively. Let be the surface area of ​​the cone tip. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0021] In one implementation, the fiber optic sidewall friction sensing module includes a second rectangular base, a second fiber optic strain sensor, a second fiber optic temperature sensor, a second deformable thin plate, and a second connecting member.

[0022] The second deformable thin plate is a rectangular steel plate, which will deform when subjected to friction deformation columns;

[0023] The second fiber optic strain sensor is arranged at the center of the inner wall of the second deformable thin plate to measure the deformation at the center of the thin plate.

[0024] The second fiber optic temperature sensor is arranged in the cavity of the second rectangular base to measure the temperature change during the penetration process;

[0025] The second rectangular base is used to fix the fiber optic cable of the fiber optic sidewall friction sensing module, the second fiber optic strain sensor and the second fiber optic temperature sensor;

[0026] The second connecting member is used to connect the second rectangular base to the second deformable thin plate.

[0027] In one implementation, the fiber optic inclinometer module includes a cylindrical counterweight, a third connecting member, and an inclinometer sensor.

[0028] The cylindrical counterweight is used to apply a load to the sensor in the fiber optic inclination sensing module when the probe is tilted, so as to determine the tilt direction and tilt angle of the probe.

[0029] The third connecting component is a connecting spring, used to connect the cylindrical counterweight and the inclinometer sensor, and to transfer the load to the inclinometer sensor;

[0030] The inclination sensor includes a third fiber optic strain sensor and a third fiber optic temperature sensor, and multiple sensors are arranged around the cylindrical counterweight. The multiple inclination sensors work together to measure the inclination direction and inclination angle of the probe.

[0031] In one implementation, the fiber optic effective stress sensing module is a hollow cylinder, comprising a sidewall deformation thin plate, an annular perforated base, a fourth fiber optic strain sensor, a fourth fiber optic temperature sensor, and a fourth connecting component.

[0032] The outer surface of the deformable sidewall plate is used to bear the effective stress and pore water pressure in the soil, while the inner sidewall is used to bear the pore water pressure.

[0033] The annular perforated base is used to conduct pore water in the soil, allowing it to enter the optical fiber effective stress sensing module and thus exert pore water pressure on the inside of the sidewall deformable thin plate.

[0034] The fourth fiber optic strain sensor is arranged at the axial center point of the inner wall of the sidewall deformable thin plate to measure the strain of the sidewall deformable thin plate.

[0035] The fourth fiber optic temperature sensor is arranged inside the cavity of the fiber optic effective stress sensing module and is used to measure the temperature change during the penetration process.

[0036] The fourth connecting member is used to connect the sidewall deformable thin plate and the annular perforated base into a hollow cylindrical cavity.

[0037] In one implementation, when the effective stress of the soil is measured by the fiber Bragg grating-based effective stress static cone penetrometer, and when the effective stress of the soil is probed by the fiber Bragg grating-based effective stress static cone penetrometer, the effective stress of the soil is calculated based on the effective stress formula and thin plate theory. The effective stress formula is:

[0038] ;

[0039] in, The effective stress of the soil. r The inner wall radius of the sidewall deformable thin plate is given. The elastic modulus of the sidewall deformable thin plate is given by [reference to a specific parameter]. The thickness of the deformable sidewall plate is given. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0040] In one implementation, the water inlet of the fiber optic effective stress sensing module is made of permeable stone to prevent the entry of external particles, and a pore water film is formed by a gradient aperture unidirectional permeable fiber membrane to establish a hydraulic connection between the water in the fiber optic effective stress sensing module and the pore water of the soil.

[0041] A hydrophilic membrane and a hydrophobic membrane are arranged on both sides of the fiber membrane to increase the amount of water entering the pores while reducing the outflow of water from the inside of the optical fiber effective stress sensing module.

[0042] In one implementation, before performing static penetration testing, the fiber optic effective stress sensing module is placed in degassing distilled water to saturate the internal cavity of the fiber optic effective stress sensing module, ensuring that there is no residual gas in the hydraulic transmission channel of the fiber optic effective stress sensing module and that it reaches a saturated state.

[0043] In one implementation, the grating demodulation module is located in the cavity inside the demodulation ring pillar and includes a broadband light source, a coupler, an optical fiber FP tunable filter, a photodetector, a signal amplifier, and a data acquisition card.

[0044] The broadband light source is used to emit broadband light of a fixed wavelength to provide optical signals for the integrated fiber optic sensing component;

[0045] The coupler transmits the optical signal emitted by the broadband light source to the integrated fiber optic sensing component and transmits the reflected optical signal back to the grating demodulation module.

[0046] The fiber optic FP tunable filter is used to perform wavelength scanning on the reflected optical signal transmitted by the coupler, so as to achieve separation and filtering of optical signals of different wavelengths.

[0047] The photodetector is used to convert the filtered and separated optical signal into an electrical signal, thus completing the photoelectric conversion process.

[0048] The signal amplifier is used to amplify the electrical signal output by the photodetector, thereby improving the signal-to-noise ratio and measurement accuracy.

[0049] The data acquisition card is used to acquire amplified electrical signals and convert them into digital signals for transmission to the host computer, so as to obtain accurate measurement values ​​of various physical parameters in real time.

[0050] Compared with the prior art, the present invention provides an effective stress static cone penetrometer based on a fiber Bragg grating. The effective stress static cone penetrometer includes a probe, a probe rod, and an integrated fiber optic sensing assembly distributed in the probe and the probe rod, wherein the probe and the probe rod are interconnected. The probe includes a cone head and a cone head deformation column. The probe rod includes an effective stress ring column, a clinometer ring column, a sidewall friction cylinder, a demodulation ring column, a grating demodulation module disposed in the cavity of the demodulation ring column, a damping cylinder, and a built-in fiber optic path. The integrated fiber optic sensing assembly includes a fiber cone tip resistance sensing module, a fiber sidewall friction resistance sensing module, a fiber clinometer sensing module, and a fiber effective stress sensing module, which are connected to the grating demodulation module via the built-in fiber optic path. The fiber cone tip resistance sensing module is disposed in the probe, the fiber sidewall friction resistance sensing module is disposed above the inner side of the sidewall friction cylinder, the fiber clinometer sensing module is disposed at the center of the clinometer ring column, and the fiber effective stress sensing module is disposed outside the effective stress ring column. The effective stress static cone penetrometer based on fiber Bragg gratings proposed in this invention solves the problems of existing technologies lacking a direct measurement instrument for effective soil stress in in-situ testing based on fiber Bragg gratings, and the significant measurement errors and weak electromagnetic interference resistance of current static cone penetrometers. Based on the effective stress static cone penetrometer based on fiber Bragg gratings provided by this invention, effective stress can be directly measured during static cone penetration testing, which is simpler than pore pressure static cone penetration testing. Furthermore, in this embodiment, fiber Bragg grating sensors based on thin-plate theory are used to measure cone tip resistance, sidewall friction, effective stress, and probe tilt direction and angle during static cone penetration testing in different arrangements. This unifies the data acquisition and analysis system, significantly improving the efficiency and accuracy of soil parameter detection. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 A structural diagram of an embodiment of the effective stress static cone penetrometer based on a fiber Bragg grating provided by the present invention;

[0053] Figure 2 A three-dimensional diagram of the fiber optic cone tip resistance sensing module of an embodiment of the effective stress static cone probe based on a fiber Bragg grating provided by the present invention.

[0054] Figure 3The front view of the fiber optic cone tip resistance sensing module of an embodiment of the effective stress static cone probe based on a fiber Bragg grating provided by the present invention.

[0055] Figure 4 A top view of the fiber optic inclinometer sensing module of an embodiment of the effective stress static cone penetrometer based on a fiber Bragg grating provided by the present invention.

[0056] Figure 5 A cross-sectional view of the fiber optic inclinometer module of an embodiment of the effective stress static cone penetrometer based on a fiber Bragg grating provided by the present invention.

[0057] Figure 6 The penetration process probe tilt angle of an embodiment of the effective stress static cone penetrometer based on fiber Bragg grating provided by the present invention;

[0058] Figure 7 The penetration process of the probe tilting direction is shown in the embodiment of the effective stress static cone penetrometer based on fiber Bragg grating provided by the present invention.

[0059] Figure 8 A top view of the fiber optic effective stress sensing module of an embodiment of the effective stress static cone penetrometer based on a fiber Bragg grating provided by the present invention.

[0060] Figure 9 A front view of the fiber optic effective stress sensing module of an embodiment of the effective stress static cone penetrometer based on a fiber Bragg grating provided by the present invention.

[0061] Figure 10 A pore water filter ring structure is provided as an embodiment of the effective stress static cone penetrometer based on fiber Bragg grating provided by the present invention.

[0062] Explanation of reference numerals in the attached figures:

[0063] 10. Probe; 20. Probe rod; 30. Integrated fiber optic sensing assembly;

[0064] 11. Cone head; 12. Cone head deformation column; 21. Effective stress ring column; 22. Inclinometer ring column; 23. Sidewall friction cylinder; 24. Demodulation ring column; 25. Grating demodulation module; 251. Fiber optic FP tunable filter; 252. Coupler; 253. Broadband light source; 254. Photodetector; 255. Signal amplifier; 256. Data acquisition card; 26. Damping cylinder; 27. Built-in fiber optic path; 28. Friction deformation column; 29. ​​Sealing ring; 31. Fiber optic cone tip resistance sensing module; 311. First rectangular base; 312. First fiber optic strain sensor; 313. First fiber optic temperature sensor; 314. 31. First deformable thin plate; 32. Fiber optic sidewall friction sensing module; 33. Fiber optic inclinometer sensing module; 331. Cylindrical counterweight; 332. Connecting spring; 333. Inclinometer sensor; 34. Fiber optic effective stress sensing module; 341. Sidewall deformable thin plate; 342. Annular perforated base; 343. Fourth fiber optic strain sensor; 344. Fourth fiber optic temperature sensor; 345. Porous water filter ring; 3451. Permeable stone; 3452. Permeable hole; 3453. Gradient pore size unidirectional permeable fiber membrane; 3454. Hydrophilic membrane; 3455. Hydrophobic membrane; 40. Probe connecting component; m. Incompressible fluid.

[0065] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0066] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of this application and not all possible implementations. Based on the embodiments in this application, those skilled in the art can obtain other embodiments without creative effort, and these embodiments are also within the protection scope of this application.

[0067] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0068] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0069] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0070] like Figure 1 As shown, this embodiment provides an effective stress static cone penetrometer based on a fiber Bragg grating. The effective stress static cone penetrometer based on a fiber Bragg grating includes a probe 10, a probe rod 20, and an integrated fiber optic sensing assembly 30 distributed in the probe 10 and the probe rod 20. The probe 10 and the probe rod 20 are interconnected.

[0071] The probe 10 includes a cone-shaped head 11 and a cone-shaped deformable post 12. In this embodiment, the probe 10 can be conical, spherical, or T-shaped, etc.

[0072] The probe rod 20 includes an effective stress ring post 21, a tilting ring post 22, a sidewall friction cylinder 23, a demodulation ring post 24, a grating demodulation module 25 disposed in the cavity of the demodulation ring post 24, a damping cylinder 26, and a built-in optical fiber path 27.

[0073] Furthermore, the probe 20 also includes a sealing ring 29, which is used to isolate moisture in the soil so that the grating demodulation module 25 remains dry.

[0074] The integrated fiber optic sensing assembly 30 includes a fiber optic tip resistance sensing module 31, a fiber optic sidewall friction sensing module 32, a fiber optic inclinometer module 33, and a fiber optic effective stress sensing module 34. It is connected to the grating demodulation module 25 via the built-in fiber optic path 27. The fiber optic tip resistance sensing module 31 is disposed in the probe 10, the fiber optic inclinometer module 33 is disposed at the center of the inclinometer ring 22, the fiber optic sidewall friction sensing module 32 is disposed above the inner side of the sidewall friction cylinder 23, and the fiber optic effective stress sensing module 34 is disposed outside the effective stress ring 21.

[0075] The grating demodulation module 25 includes an optical fiber FP tunable filter 251, a coupler 252, a broadband light source 253, a photodetector 254, a signal amplifier 255, and a data acquisition card 256.

[0076] The probe rod 20 is connected to the probe body based on the probe rod connecting component.

[0077] Reference Figure 2 and Figure 3 , Figure 2 This is a three-dimensional diagram of the fiber optic cone tip resistance sensing module 31. Figure 3 This is a front view of the fiber optic taper resistance sensing module 31.

[0078] Specifically, the fiber optic cone tip resistance sensing module 31 includes a first rectangular base 311, a first fiber optic strain sensor 312, a first fiber optic temperature sensor 313, a first deformable thin plate 314, and a first connecting member.

[0079] The first deformable thin plate 314 is a rectangular steel plate, which will deform when subjected to the action of the conical deformable column 12;

[0080] The first fiber optic strain sensor 312 is arranged at the center of the inner wall of the first deformable thin plate 314 and is used to measure the deformation at the center of the thin plate.

[0081] The first fiber optic temperature sensor 313 is arranged in the cavity of the first rectangular base 311 and is used to measure the temperature change during the penetration process.

[0082] The first rectangular base 311 is used to fix the optical fiber cable of the optical fiber cone resistance sensing module 31, the first optical fiber strain sensor 312 and the first optical fiber temperature sensor 313;

[0083] The first connecting member is used to connect the first rectangular base 311 to the first deformable thin plate 314. It should be noted that the first connecting member is not shown in the figure.

[0084] Furthermore, an incompressible fluid m is also included above the first deformable thin plate 314. The incompressible fluid m is used to uniformly transfer the external load to the deformable thin plate, causing the thin plate to deform.

[0085] Reference Figure 3 As can be seen, the first fiber optic strain sensor 312 is placed at the center of the first deformable thin plate 314 to measure the deformation of the first deformable thin plate 314 under external load. The first fiber optic temperature sensor 313 is arranged in the cavity of the first fiber optic strain sensor 312 to determine the cone tip resistance based on the measured strain and temperature.

[0086] The first deformable thin plate 314 is a high-strength rectangular thin plate. The first fiber optic strain sensor 312 is arranged at the center of the inner wall of the rectangular thin plate. When the effective stress of the soil is measured by the effective stress static cone penetrometer based on the fiber Bragg grating, the resistance experienced by the probe 10 is calculated based on the cone tip resistance formula, which is:

[0087] ;

[0088] in, For cone tip resistance, D Let be the bending stiffness of the first deformed thin plate. Let be the thickness of the first deformed thin plate. a and b These are the length and width of the first deformed thin plate, respectively. Let be the surface area of ​​the cone tip. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0089] Specifically, the fiber optic cone tip resistance sensing module is used to measure the resistance experienced by the cone tip during the penetration of the probe. Based on the basic principle of the FBG sensor, its reflected light Bragg wavelength shift... The first formula can be used to describe this:

[0090] ;

[0091] in, For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. Let be the strain along the length direction at the center of the first deformed thin plate. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0092] Assuming external loads p When the strain is uniformly applied to the first deformed thin plate, according to thin plate theory, the strain along the length direction at the center of the plate is... The second formula can be used for calculation:

[0093] ;

[0094] in, Let be the thickness of the first deformed thin plate. a and b These are the length and width of the first deformed thin plate, respectively. D Let be the bending stiffness of the first deformed thin plate, and , Let be the elastic modulus of the first deformed thin plate. It is Poisson's ratio.

[0095] Substituting the second formula into the first formula, the load can be derived. p The third formula relating strain to strain:

[0096] ;

[0097] Because the cone tip resistance is transmitted to the sensor deformation sheet through the cone head deformation column during penetration, the cone tip resistance... The following relationship exists between the sensor deformation sheet and the sensor, as shown in the fourth formula:

[0098] ;

[0099] in, Let be the surface area of ​​the cone tip, which is also the area subjected to force. Substituting the third formula into the fourth formula shown, we can obtain the cone tip resistance formula:

[0100] ;

[0101] Reference Figure 1 The fiber optic sidewall friction sensing module 32 includes a second rectangular base, a second fiber optic strain sensor, a second fiber optic temperature sensor, a second deformable thin plate, and a second connecting component.

[0102] The second deformable sheet is a rectangular steel plate, which will deform when subjected to the friction deformation column 28;

[0103] The second fiber optic strain sensor is arranged at the center of the inner wall of the second deformable thin plate to measure the deformation at the center of the thin plate.

[0104] The second fiber optic temperature sensor is arranged in the cavity of the second rectangular base to measure the temperature change during the penetration process;

[0105] The second rectangular base is used to fix the fiber optic cable of the fiber optic sidewall friction sensing module, the second fiber optic strain sensor and the second fiber optic temperature sensor;

[0106] The second connecting member is used to connect the second rectangular base to the second deformable thin plate.

[0107] The optical fiber sidewall friction sensing module 32 has the same structure as the optical fiber taper resistance sensing module 31. Further, referring to... Figure 1 It can be seen that the probe rod 20 also includes a friction deformation column 28. The frictional resistance experienced by the side wall is transmitted to the friction deformation column 28 through the side wall friction cylinder 23, and further transmitted to the cone tip resistance sensing module via the incompressible fluid m.

[0108] Reference Figure 4 and Figure 5 , Figure 4 This is a top view of the fiber optic inclinometer module. Figure 5 Here is a cross-sectional view of the fiber optic inclinometer module:

[0109] The fiber optic inclinometer module 33 includes a cylindrical counterweight 331, a third connecting component, and a fiber optic inclinometer sensor 333.

[0110] The cylindrical counterweight 331 is used to apply a load to the inclinometer 333 in the fiber optic inclinometer module 33 when the probe 20 is tilted, so as to determine the tilting direction and tilting angle of the probe 20.

[0111] The third connecting component is a connecting spring 332, which is used to connect the cylindrical counterweight 331 and the inclinometer 333, and to transfer the load to the inclinometer 333.

[0112] The inclinometer 333 comprises a deformable sheet, a third fiber optic strain sensor, and a third fiber optic temperature sensor, with multiple sensors arranged around the cylindrical counterweight 331. These multiple inclinometers 333 work together to measure the tilt direction and tilt angle of the probe 20. It should be noted that the deformable sheet, the third fiber optic strain sensor, and the third fiber optic temperature sensor are not shown in the figure.

[0113] Specifically, there are four inclinometer sensors 333, evenly distributed in the four directions of the cylindrical counterweight 331, for reference. Figure 4The numbers 1, 2, 3, and 4 in the diagram correspond to the first target inclinometer sensor, the second target inclinometer sensor, the third target inclinometer sensor, and the fourth target inclinometer sensor, respectively.

[0114] Specifically, the fiber optic inclinometer module is used to measure the inclination angle and direction of the probe during penetration. For example... Figure 6 As shown, if the probe tilts towards the third and fourth target inclinometers during penetration, the force generated by the tilting of the cylindrical counterweight acts on the third and fourth target inclinometers, causing the deformable sheet to deform. The magnitude of the force acting on the inclinometer at this time can be calculated using the force formula:

[0115] ;

[0116] Assume that the forces acting on the third target inclinometer and the fourth target inclinometer are respectively and The tilt direction of the probe rod can then be calculated using the target tilt formula:

[0117] ;

[0118] ;

[0119] in, The angle of inclination of the probe relative to the horizontal direction. Let G be the angle of inclination of the probe relative to the vertical direction, and G be the weight of the cylindrical counterweight. Figure 6 and Figure 7 As shown.

[0120] Reference Figure 8 , Figure 8 This is a top view of the fiber optic effective stress sensing module 34. It can be seen that the fiber optic effective stress sensing module 34 is a hollow cylinder, including a sidewall deformation thin plate 341, an annular perforated base 342, a fourth fiber optic strain sensor 343, a fourth fiber optic temperature sensor 344, and a fourth connecting member.

[0121] The outer surface of the sidewall deformable thin plate 341 is used to bear the effective stress and pore water pressure in the soil, and the inner sidewall is used to bear the pore water pressure.

[0122] The annular perforated base 342 is used to conduct pore water in the soil, allowing it to enter the optical fiber effective stress sensing module 34 and thus apply pore water pressure to the inside of the sidewall deformable thin plate 341.

[0123] The fourth fiber optic strain sensor 343 is arranged at the axial center point of the inner wall of the sidewall deformable thin plate 341 to measure the strain of the sidewall deformable thin plate 341.

[0124] The fourth fiber optic temperature sensor 344 is arranged inside the cavity of the fiber optic effective stress sensing module 34 and is used to measure the temperature change during the penetration process.

[0125] The fourth connecting member is used to connect the sidewall deformable thin plate 341 and the annular perforated base 342 into a hollow cylindrical cavity.

[0126] When performing soil testing with the effective stress static cone penetrometer based on fiber Bragg gratings, the effective stress of the soil is calculated based on the effective stress formula and thin plate theory. The effective stress formula is as follows:

[0127] ;

[0128] in, The effective stress of the soil. r The inner wall radius of the sidewall deformable thin plate is given. The elastic modulus of the sidewall deformable thin plate is given by [reference to a specific parameter]. The thickness of the deformable sidewall plate. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0129] Specifically, the front view of the fiber optic effective stress sensing module 34 is as follows: Figure 9 As shown, the fourth fiber optic strain sensor 343 and the fourth fiber optic temperature sensor 344 are used to measure the strain and temperature changes caused by effective stress during penetration, respectively. During measurement, pore water inside the soil enters the fiber optic effective stress sensing module 34 through the pore water filter ring 345 at the inlet, causing the pore water pressure inside and outside the fiber optic effective stress sensing module 34 to be balanced. At this time, the pressure acting on the fiber optic effective stress sensing module 34 is the effective stress of the soil. Therefore, the fiber optic effective stress sensing module 34 can be used to directly measure the effective stress of the soil during penetration.

[0130] According to the effective stress principle, the effective stress in soil can be calculated using the fifth formula:

[0131] ;

[0132] in, and These are the total soil stress and the effective soil stress, respectively. This represents the pore water pressure in the soil.

[0133] According to thin plate theory, the internal and external stresses of the sidewall deformable thin plate satisfy the following formulas of thin plate theory:

[0134] ;

[0135] in, r The inner wall radius of the sidewall deformable thin plate is given. d and These are the height and thickness of the deformable sidewall plate, respectively. Let be the circumferential stress of the deformable thin plate on the sidewall. Therefore, the strain at the center of the deformable thin plate on the sidewall can be calculated using the central strain formula:

[0136] ;

[0137] According to the fifth formula, the effective stress formula can be obtained as follows:

[0138] ;

[0139] in, The effective stress of the soil. r The inner wall radius of the sidewall deformable thin plate is given. The elastic modulus of the sidewall deformable thin plate is given by [reference to a specific parameter]. The thickness of the deformable sidewall plate is given. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

[0140] Furthermore, referring to Figure 10 , Figure 10 The pore water filter ring 345 structure at the water inlet of the fiber optic effective stress sensing module 34 is specifically designed as follows: the water inlet of the fiber optic effective stress sensing module 34 uses a permeable stone 3451 to prevent the entry of external particles, and a pore water film is formed by a gradient aperture unidirectional permeable fiber membrane 3453 to establish a hydraulic connection between the water inside the fiber optic effective stress sensing module 34 and the pore water of the soil.

[0141] A hydrophilic membrane 3454 and a hydrophobic membrane 3455 are respectively arranged on both sides of the fiber membrane to increase the amount of pore water entering while reducing the outflow of water from the effective stress sensing module 34 of the optical fiber.

[0142] Specifically, the porous water filter ring 345 includes the permeable stone 3451 and the gradient pore size unidirectional permeable fiber membrane 3453, such as Figure 10 As shown. The permeable stone 3451 is in direct contact with the soil, allowing pore water to flow while preventing soil particles from entering. A gradient-pore-size unidirectional permeable fiber membrane 3453 is arranged on the side of the permeable stone 3451 closest to the pore water. A hydrophilic membrane 3454 and a hydrophobic membrane 3455 are respectively arranged on both sides of the gradient-pore-size unidirectional permeable fiber membrane 3453, increasing the amount of pore water entering while reducing water outflow from the fiber optic effective stress sensing module 34.

[0143] In this embodiment, before performing static penetration testing, the fiber optic effective stress sensing module 34 is placed in degassing distilled water to saturate the internal cavity of the fiber optic effective stress sensing module 34, ensuring that there is no residual gas in the hydraulic transmission channel of the fiber optic effective stress sensing module 34 and that it reaches a saturated state.

[0144] Specifically, the fiber optic effective stress sensing module 34 needs to be soaked in degassing distilled water before use to saturate its interior and form a water film inside the permeable membrane, ensuring that the fiber optic effective stress sensing module 34 is permeable to water but not air. During penetration, the pore water in the soil forms a hydraulic connection with the water inside the fiber optic effective stress sensing module 34, thereby transmitting the pore water pressure in the soil.

[0145] Specifically, during the penetration process of the fiber Bragg grating-based effective stress static cone penetrometer, when the soil layer is normally consolidated, the pore water pressure is positive. Pore water enters the soil and exerts pressure on the interior of the deformable sidewall plate 341, balancing the external pore water pressure. When the soil layer is overconsolidated, the pore water pressure is negative. At this time, water inside the fiber optic effective stress sensing module 34 flows out through the gradient aperture unidirectional permeable fiber membrane 3453, creating a negative pressure inside the fiber optic effective stress sensing module 34, which acts on the interior of the deformable sidewall plate 341. The fiber optic effective stress sensing module 34 can be used to measure the effective stress in normally consolidated and overconsolidated soils.

[0146] In other words, before the effective stress static penetrometer based on the fiber Bragg grating is inserted, it needs to be saturated with degassing distilled water to ensure that the internal cavity of the fiber effective stress sensing module 34 is saturated.

[0147] Reference Figure 1 The grating demodulation module 25 is located in the cavity inside the demodulation ring post 24 and includes a broadband light source 253, a coupler 252, an optical fiber FP tunable filter 251, a photodetector 254, a signal amplifier 255, and a data acquisition card 256.

[0148] The broadband light source 253 is used to emit broadband light of a fixed wavelength to provide optical signals for the integrated fiber optic sensing component 30.

[0149] The coupler 252 transmits the optical signal emitted by the broadband light source 253 to the integrated fiber optic sensing component and transmits the reflected optical signal back to the grating demodulation module 25.

[0150] The fiber optic FP tunable filter 251 is used to perform wavelength scanning on the reflected optical signal transmitted by the coupler 252, so as to achieve separation and filtering of optical signals of different wavelengths.

[0151] The photodetector 254 is used to convert the filtered and separated optical signal into an electrical signal, thus completing the photoelectric conversion process.

[0152] The signal amplifier 255 is used to amplify the electrical signal output by the photodetector to improve the signal-to-noise ratio and measurement accuracy.

[0153] The data acquisition card 256 is used to acquire the amplified electrical signal and convert the amplified electrical signal into a digital signal to transmit to the host computer in order to obtain the accurate measurement values ​​of each physical parameter in real time.

[0154] During the penetration process of the probe, the broadband light source 253 emits broadband light of a fixed wavelength. Simultaneously, the coupler 252 transmits the broadband light to the fiber Bragg grating sensor and receives its reflected light. The fiber FP tunable filter 251 is used to dynamically scan the transmission wavelength, and the photodetector 254 converts the optical signal into an electrical signal. Then, the weak electrical signal is amplified by the signal amplifier 255. The input of the signal amplifier 255 is connected to the signal acquisition card, and finally connected to the built-in fiber optic path 27, which is the optical-electrical signal processing path, to demodulate data such as cone tip resistance, sidewall friction, effective stress, tilt angle, and penetration depth in real time.

[0155] In summary, this embodiment provides an effective stress static cone penetrometer based on a fiber Bragg grating. The effective stress static cone penetrometer includes a probe 10, a probe rod 20, and an integrated fiber optic sensing assembly 30 distributed in the probe 10 and the probe rod 20. The probe 10 and the probe rod 20 are interconnected. The probe includes a cone head 11 and a cone head deformation column 12. The probe rod 20 includes an effective stress ring column 21, a tilting ring column 22, a sidewall friction cylinder 23, a demodulation ring column 24, a grating demodulation module 25 disposed in the cavity of the demodulation ring column 24, a damping cylinder 26, and a built-in fiber optic path 27. The integrated fiber optic sensing assembly 30 includes a fiber optic cone tip resistance sensing module 31, a fiber optic sidewall friction resistance sensing module 32, a fiber optic inclinometer module 33, and a fiber optic effective stress sensing module 34. It is connected to the grating demodulation module 25 via the built-in fiber optic path 27. The fiber optic cone tip resistance sensing module 31 is located within the probe 10; the fiber optic sidewall friction resistance sensing module 32 is located above the inner side of the sidewall friction cylinder 23; the fiber optic inclinometer module 33 is located at the center of the inclinometer ring column 22; and the fiber optic effective stress sensing module 34 is located outside the effective stress ring column 21. The effective stress static cone penetrometer based on a fiber Bragg grating proposed in this embodiment solves the problems of the lack of a penetrometer for direct measurement of effective soil stress in in-situ testing based on a fiber Bragg grating, and the significant measurement errors and weak electromagnetic interference resistance of current static cone penetrometers. Based on the effective stress static cone penetrometer based on fiber Bragg grating provided in this embodiment, the effective stress in static cone penetration can be directly measured, which is simpler than pore pressure static cone penetration. At the same time, in this embodiment, fiber Bragg grating sensors based on thin plate theory are used to measure the cone tip resistance, side wall friction, effective stress, and probe tilt direction and angle during static cone penetration in different arrangement forms. This unifies the data acquisition and analysis system and significantly improves the efficiency and accuracy of soil parameter detection.

[0156] In the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0157] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0158] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0159] It should be noted that, in this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0160] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0161] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An effective stress static cone penetrometer based on a fiber Bragg grating, characterized in that, The effective stress static cone penetrometer based on fiber Bragg grating includes a probe, a probe rod, and an integrated fiber optic sensing component distributed in the probe and the probe rod, wherein the probe and the probe rod are interconnected. The probe includes a cone head and a cone head deformation column; The probe rod includes an effective stress ring column, a tilt measuring ring column, a sidewall friction cylinder, a demodulation ring column, a grating demodulation module disposed in the cavity of the demodulation ring column, a damping cylinder, and a built-in optical fiber path; The integrated fiber optic sensing assembly includes a fiber optic tip resistance sensing module, a fiber optic sidewall friction sensing module, a fiber optic inclinometer module, and a fiber optic effective stress sensing module. It is connected to the grating demodulation module based on the built-in fiber optic path. The fiber optic tip resistance sensing module is disposed in the probe, the fiber optic inclinometer module is disposed at the center of the inclinometer ring, the fiber optic sidewall friction sensing module is disposed above the inner side of the sidewall friction cylinder, and the fiber optic effective stress sensing module is disposed outside the effective stress ring. The fiber optic cone tip resistance sensing module includes a first rectangular base, a first fiber optic strain sensor, a first fiber optic temperature sensor, a first deformable thin plate, and a first connecting component. The first deformable thin plate is a rectangular steel plate, which will deform when subjected to the action of the conical deformable column; The first fiber optic strain sensor is arranged at the center of the inner wall of the first deformable thin plate to measure the deformation at the center of the thin plate. The first fiber optic temperature sensor is arranged in the cavity of the first rectangular base to measure the temperature change during the penetration process. The first rectangular base is used to fix the optical fiber cable, the first optical fiber strain sensor and the first optical fiber temperature sensor in the optical fiber taper resistance sensing module; The first connecting member is used to connect the first rectangular base to the first deformable thin plate; The fiber optic effective stress sensing module is a hollow cylinder, comprising a sidewall deformation thin plate, an annular perforated base, a fourth fiber optic strain sensor, a fourth fiber optic temperature sensor, and a fourth connecting component. The outer surface of the deformable sidewall plate is used to bear the effective stress and pore water pressure in the soil, while the inner sidewall is used to bear the pore water pressure. The annular perforated base is used to conduct pore water in the soil, allowing it to enter the optical fiber effective stress sensing module and thus exert pore water pressure on the inside of the sidewall deformable thin plate. The fourth fiber optic strain sensor is arranged at the axial center point of the inner wall of the sidewall deformable thin plate to measure the strain of the sidewall deformable thin plate. The fourth fiber optic temperature sensor is arranged inside the cavity of the fiber optic effective stress sensing module and is used to measure the temperature change during the penetration process. The fourth connecting member is used to connect the sidewall deformable thin plate and the annular perforated base into a hollow cylindrical cavity.

2. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, The first deformable thin plate is a rectangular thin plate, and the first fiber optic strain sensor is arranged at the center of the inner wall of the rectangular thin plate. When the effective stress of the soil is measured by the effective stress static cone penetrometer based on the fiber Bragg grating, the resistance experienced by the probe is calculated based on the cone tip resistance formula, which is: ； in, For cone tip resistance, D Let be the bending stiffness of the first deformed thin plate. Let be the thickness of the first deformed thin plate. a and b These are the length and width of the first deformed thin plate, respectively. Let be the surface area of ​​the cone tip. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

3. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, The fiber optic sidewall friction sensing module includes a second rectangular base, a second fiber optic strain sensor, a second fiber optic temperature sensor, a second deformable thin plate, and a second connecting component. The second deformable thin plate is a rectangular steel plate, which will deform when subjected to friction deformation columns; The second fiber optic strain sensor is arranged at the center of the inner wall of the second deformable thin plate to measure the deformation at the center of the thin plate. The second fiber optic temperature sensor is arranged in the cavity of the second rectangular base to measure the temperature change during the penetration process; The second rectangular base is used to fix the fiber optic cable of the fiber optic sidewall friction sensing module, the second fiber optic strain sensor and the second fiber optic temperature sensor; The second connecting member is used to connect the second rectangular base to the second deformable thin plate.

4. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, The fiber optic inclinometer module includes a cylindrical counterweight, a third connecting component, and an inclinometer sensor. The cylindrical counterweight is used to apply a load to the sensor in the fiber optic inclination sensing module when the probe is tilted, so as to determine the tilt direction and tilt angle of the probe. The third connecting component is a connecting spring, used to connect the cylindrical counterweight and the inclinometer sensor, and to transfer the load to the inclinometer sensor; The inclinometer sensor includes a third fiber optic strain sensor and a third fiber optic temperature sensor, and multiple sensors are arranged around the cylindrical counterweight. The multiple inclinometer sensors work together to measure the inclination direction and inclination angle of the probe.

5. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, When performing soil testing with the effective stress static cone penetrometer based on fiber Bragg gratings, the effective stress of the soil is calculated based on the effective stress formula and thin plate theory. The effective stress formula is as follows: ； in, The effective stress of the soil. r The inner wall radius of the sidewall deformable thin plate is given. The elastic modulus of the deformable sidewall plate is given by [reference needed]. The thickness of the deformable sidewall plate. For the effective elastic coefficient, The initial Bragg wavelength, The wavelength change caused by strain. The coefficient of thermal expansion of optical fiber. The effective thermo-optic coefficient of the optical fiber. This represents the change in temperature.

6. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, The water inlet of the fiber optic effective stress sensing module uses permeable stone to prevent the entry of external particles, and a pore water film is formed by a gradient aperture unidirectional permeable fiber membrane to establish a hydraulic connection between the water in the fiber optic effective stress sensing module and the pore water in the soil. A hydrophilic membrane and a hydrophobic membrane are respectively arranged on both sides of the fiber membrane to increase the amount of pore water entering while reducing the outflow of water from the effective stress sensing module of the optical fiber.

7. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, Before performing static penetration testing, the fiber optic effective stress sensing module is placed in degassing distilled water to saturate the internal cavity of the fiber optic effective stress sensing module, ensuring that there is no residual gas in the hydraulic transmission channel of the fiber optic effective stress sensing module and that it reaches a saturated state.

8. The effective stress static cone penetrometer based on fiber Bragg grating according to claim 1, characterized in that, The grating demodulation module is located in the cavity inside the demodulation ring column and includes a broadband light source, a coupler, an optical fiber FP tunable filter, a photodetector, a signal amplifier, and a data acquisition card. The broadband light source is used to emit broadband light of a fixed wavelength to provide optical signals for the integrated fiber optic sensing component; The coupler transmits the optical signal emitted by the broadband light source to the integrated fiber optic sensing component and transmits the reflected optical signal back to the grating demodulation module. The fiber optic FP tunable filter is used to perform wavelength scanning on the reflected optical signal transmitted by the coupler, so as to achieve separation and filtering of optical signals of different wavelengths. The photodetector is used to convert the filtered and separated optical signal into an electrical signal, thus completing the photoelectric conversion process. The signal amplifier is used to amplify the electrical signal output by the photodetector, thereby improving the signal-to-noise ratio and measurement accuracy. The data acquisition card is used to acquire amplified electrical signals and convert them into digital signals for transmission to the host computer, so as to obtain accurate measurement values ​​of various physical parameters in real time.

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