Road settlement meter based on optical fiber technology

Abstract

The utility model discloses a road settlement meter based on an optical fiber technology and belongs to the field of civil engineering measurement. The utility model aims to solve the problem that the traditional settlement meter cannot realize the measurement of single-point differential settlement. The fiber grating settlement meter comprises a settlement meter shell, a supporting cross beam, a fiber grating and a connecting piece, the settlement meter shell is provided with a settlement bottom plate which can move in the vertical direction and deflect in the horizontal direction, the supporting cross beam is of a long-strip-shaped structure with elastic deformation and rebound capacity, and the supporting cross beam is horizontally installed in the settlement meter shell and located on the extending face of the split of the settlement bottom plate; the supporting cross beam is connected with the settlement bottom plate through a connecting piece; the fiber bragg grating is arranged in the middle of the supporting cross beam, and the length direction of the fiber bragg grating is consistent with the length direction of the supporting cross beam. The subgrade settlement measuring device is mainly used for measuring subgrade settlement.

Description

Technical Field

[0001] The utility model belongs to the field of civil engineering measurement, and in particular relates to a road settlement meter based on optical fiber technology. Background Art

[0002] The settlement of foundations can cause diseases and even disasters in structures such as roads, bridges, and tunnels during their service, especially in the seasonally frozen areas in northern my country, which are greatly affected by the ambient temperature. In winter, the water inside the foundation of the structure freezes and frost heave occurs; in summer, the ice melts, the internal volume shrinks, pores are generated, and thaw settlement occurs. Since frost heave and thaw settlement occur randomly, uneven settlement will cause catastrophic accidents such as road cracking, increased bridge load, tunnel lining sinking and collapse for the infrastructure structures built on top. Since the foundation is buried in the lowest layer of the structure, diseases are often difficult to detect and repair. Therefore, it is very necessary to monitor the settlement of the structural foundation in real time and to deal with and maintain it immediately to avoid further disasters in the structure.

[0003] With the development of fiber optic sensing technology, fiber optic sensors have been widely used in civil engineering, aerospace, petrochemical, electric power, medical and shipbuilding industries due to their advantages of anti-electromagnetic interference, corrosion resistance, high insulation, wide measurement range and easy multiplexing into networks. Among them, fiber optic Bragg grating sensors and distributed fiber optic sensors are common. Taking fiber optic Bragg grating sensors as an example, when the external force on the fiber optic Bragg grating changes, the strain distribution at the grating changes accordingly, changing the grating pitch, thereby causing the change of the center wavelength of the fiber optic Bragg grating; through the fiber optic Bragg grating demodulation equipment, the change of the center wavelength can be converted into a change of optical power, and the deformation can be detected by detecting the change of optical power.

[0004] However, the location of foundation settlement is random, making it difficult to determine the size and unevenness of the settlement, and thus making it even more difficult to assess the internal damage state of the structure. Traditional settlement meters regard the observation point as a point, and the settlement result only represents the settlement value of that point. However, civil engineering structures are complex, and the settlement of the structural foundation is not just a single point. Uneven settlement can also occur at the same point. In addition, the existing settlement meters have poor adaptability to foundation materials, and the probes need to be buried deep in the foundation, resulting in complex installation and mostly electrical tests. The output results are current, voltage, etc., and the test accuracy is easily affected by the surrounding environment. Therefore, developing a fiber optic settlement meter that can measure the uneven settlement of the structural foundation in real time is an urgent problem that technicians in this field need to solve. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a road settlement meter based on optical fiber technology. When the roadbed settles, the bottom plate sinks, and the variable-section beam connected to the bottom plate is deformed, so that the optical fiber grating arranged on the variable-section beam is deformed, thereby realizing the monitoring of foundation settlement.

[0006] The technical solution adopted by the utility model to solve the above technical problems is:

[0007] A road settlement meter based on optical fiber technology comprises a settlement meter housing, a supporting crossbeam, an optical fiber Bragg grating and a connecting piece; the settlement meter housing has a settlement bottom plate which can move in the vertical direction and deflect in the horizontal direction, the supporting crossbeam is a long strip structure with elastic deformation and rebound capabilities, the supporting crossbeam is horizontally installed in the settlement meter housing and is located on the extension surface of the dividing surface in the settlement bottom plate; the supporting crossbeam and the settlement bottom plate are connected by a connecting piece; the optical fiber Bragg grating is centrally arranged on the supporting crossbeam, and the length direction of the optical fiber Bragg grating is consistent with the length direction of the supporting crossbeam.

[0008] Preferably, the connecting member is two elastic connecting members which are arranged along the length direction of the supporting crossbeam and symmetrically on both sides of the fiber grating, and the stretching direction of each elastic connecting member is vertical.

[0009] Preferably, the sedimentation meter housing also has a top cover and a circular sleeve, the top cover is arranged at the upper port of the circular sleeve and seals the upper port of the circular sleeve; the sedimentation bottom plate is arranged in the lower port of the circular sleeve and is clearance-matched with the inner wall of the circular sleeve.

[0010] Preferably, the top cover is buckled at the upper end of the circular sleeve and fixedly connected by screws.

[0011] Preferably, a sealing gasket is provided between the top cover and the circular sleeve.

[0012] Preferably, an annular bearing platform is coaxially arranged inside the circular sleeve, and both ends of the supporting beam in the length direction are respectively mounted on the annular bearing platform and fixed by screws.

[0013] Preferably, a lead-in hole is opened on the side wall of the circular sleeve, and the optical fiber of the fiber grating passes through the lead-in hole and is connected to the signal input end of the demodulator. The lead-in hole is sealed.

[0014] Preferably, a mounting surface is provided on the outside of the circular sleeve.

[0015] Preferably, the supporting crossbeam is a variable-section beam, and the cross-section gradually decreases along the length direction.

[0016] Preferably, two fiber gratings are arranged, and are respectively arranged on the upper surface and the lower surface of the supporting beam.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] 1. This application uses fiber grating as a sensing element, which makes the settlement meter have the advantages of anti-electromagnetic interference, high sensitivity, high test accuracy, and strong durability. The sensor can realize real-time dynamic monitoring. The real-time monitoring data can reflect the size of foundation settlement, the evolution law from scratch and the expansion process, and meet the needs of foundation settlement monitoring in the field of civil engineering. In addition, the optical fiber transmission loss is small, and long-distance remote control monitoring can be realized. Furthermore, the fiber grating has good insulation performance, a wide range of applications, and is safe and reliable. The optical fiber itself is composed of electrolytes and does not require power drive.

[0019] 2. Since the fiber Bragg grating is sensitive to both temperature and force, the present application sets up a temperature-compensating fiber Bragg grating as needed, that is, the fiber Bragg grating is arranged on the upper and lower surfaces of the variable-section beam respectively, wherein the wavelength of the compressed fiber Bragg grating will decrease after being compressed, and the observed wavelength signal actually reflects the temperature-force (assuming the temperature rises); the wavelength of the tensile fiber Bragg grating will increase after being tensile, and the observed wavelength signal actually reflects the temperature+force. Therefore, after the two wavelength signals are decoupled, the sensor measurement error caused by temperature (thermal expansion and contraction) in the real-time measurement process can be eliminated, thereby improving the measurement accuracy.

[0020] 3. The settlement meter of the present application can be installed by coring and backfilling, and can monitor the built roadbed. At the same time, through the lead welding of the lead hole, multiple settlement meters can be connected in series for quasi-distributed measurement, and the measuring points can be arbitrarily allocated.

[0021] 4. This application can realize the perception and monitoring of the foundation settlement of structures such as bridges, tunnels and roads. The settlement meter is buried inside the foundation structure. During the long-term service of the structure, affected by the load and environment, the structure will settle in different time periods throughout the year and under long-term load conditions. Due to the effect of settlement, the bottom plate sinks, the variable cross-section beam deforms, and the fiber grating deforms, thereby realizing foundation settlement monitoring. When uneven settlement occurs in the monitoring area, the settlement bottom plate will tilt, and the two springs will be subjected to inconsistent forces, so the supporting beam will deform unevenly and be transmitted to the fiber grating. The material mechanics method can be back-calculated through the terminal processing equipment to calculate the specific situation of the uneven settlement. Therefore, this application can also monitor the uneven settlement of the observation point. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] As a part of this application, the accompanying drawings are used to provide a further understanding of the present invention.

[0023] Figure 1Schematic diagram of the overall structure of the sedimentation meter.

[0024] Figure 2 This is a diagram of the disassembly of the sedimentation meter.

[0025] Figure 3 Schematic diagram of the cross section of the sedimentation meter.

[0026] Figure 4 Schematic diagram of the structure of the circular sleeve in the sedimentation gauge.

[0027] Figure 5 This is a schematic diagram of the structure of the top cover in the sedimentation meter.

[0028] Figure 6 Schematic diagram of the combination of the variable-section beam, spring and fiber Bragg grating of the settlement gauge.

[0029] Explanation of the reference numerals: 1-sedimentation meter housing; 1-1-sedimentation bottom plate; 1-2-top cover; 1-3-circular sleeve; 1-3-1-annular supporting platform; 1-3-2-lead hole; 1-3-3-mounting surface; 2-supporting beam; 3-fiber Bragg grating; 4-connector; 4-1-stress pull ring. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. The following embodiments are used to illustrate the utility model but are not used to limit the scope of the utility model.

[0031] See also Figure 1 The embodiment of the present application provides a road settlement meter based on optical fiber technology, including a settlement meter housing 1, a supporting beam 2, an optical fiber Bragg grating 3 and a connecting piece 4; wherein the settlement meter housing 1 has a settlement bottom plate 1-1 that can move in the vertical direction and deflect in the horizontal direction, and the supporting beam 2 is a long strip structure with elastic deformation and rebound capabilities, and the supporting beam 2 is horizontally installed in the settlement meter housing 1 and is on the extension surface of the dividing surface in the settlement bottom plate 1-1; a certain distance is left between the supporting beam 2 and the settlement bottom plate 1-1, and the supporting beam 2 is connected to the settlement bottom plate 1-1 through a connecting piece 4; the optical fiber Bragg grating 3 is centrally arranged on the supporting beam 2, and the length direction of the optical fiber Bragg grating 3 is consistent with the length direction of the supporting beam 2.

[0032] In this embodiment, since the fiber Bragg grating 3 realizes the measurement function through deformation, the support beam 2 used to support the fiber Bragg grating 3 needs to have elastic deformation ability under the action of external force. The settlement bottom plate 1-1 is connected to the support beam 2 through the connecting piece 4, so the settlement bottom plate 1-1 is the power source for the deformation of the support beam 2. In this embodiment, the settlement bottom plate 1-1 is set as a movable structure. When uniform settlement and uneven settlement occur in the monitoring area, the settlement bottom plate 1-1 produces corresponding movement, that is, movement in the vertical direction or deflection movement in the horizontal direction, thereby generating different pulling forces on the support beam 2 to achieve deformation. Among them, since the settlement of the foundation structure is obtained by tangibly measuring the movement of the settlement bottom plate 1-1 and the deformation of the supporting beam 2, whether the entire settlement of the foundation structure can be completely measured is closely related to the arrangement positions of the settlement bottom plate 1-1, the supporting beam 2 and the connecting member 4. In this embodiment, the supporting beam 2 is arranged on the center plane of the settlement meter housing 1, which is actually arranged on the center plane of the settlement bottom plate 1-1, so that the center of gravity of the supporting beam 2 and the center of gravity of the settlement bottom plate 1-1 are in the same plane, thereby avoiding eccentric movement of the settlement bottom plate 1-1 during the measurement process and ensuring the measurement accuracy.

[0033] In addition, this embodiment also includes a demodulator and a terminal processing device. The sedimentation meter is used as a sensor. The measured optical fiber signal is transmitted to the demodulator for demodulation, and the demodulated data is then transmitted to the terminal processing device for resolution. It should be noted that this application only protects the sedimentation meter structure itself, and the resolution of the data is not the key point protected by this application. The settlement meter is buried inside the foundation structure by coring. In the specific implementation process, since the settlement bottom plate 1-1 has the freedom to move up and down, and since the settlement bottom plate 1-1 is connected to the supporting beam 2 by the connecting piece 4, when settlement occurs in the monitoring area, the settlement bottom plate 1-1 moves downward under the action of its own gravity, and the connecting piece 4 is subjected to tension and transmitted to the supporting beam 2. Through the coordinated deformation between the fiber optic Bragg grating 3 and the supporting beam 2, the fiber optic Bragg grating 3 arranged on the surface of the supporting beam 2 is deformed, the grating pitch becomes larger, and then the optical signal changes. The optical signal is transmitted to the demodulator and the terminal processing equipment, and the relationship between the change in the optical signal and the settlement amount is established through the indoor calibration test relationship, thereby monitoring the foundation settlement.

[0034] Furthermore, in order to realize the measurement of uneven settlement of the monitoring point, the connector 4 described in this embodiment is two elastic connectors along the length direction of the supporting beam 2 and symmetrically arranged on both sides of the fiber grating 3, and the stretching direction of each elastic connector is vertical; specifically, the top end of the elastic connector is connected to the supporting beam 2, and the bottom end of the elastic connector extends longitudinally downward and is connected to the settlement bottom plate 1-1.

[0035] Among them, the elastic connecting member is preferably a spring. In order to facilitate the connection and disassembly of the spring with the supporting beam 2 and the sedimentation bottom plate 1-1, a force pull ring 4-1 can be set at the corresponding connection between the sedimentation bottom plate 1-1 and the supporting beam 2, and the two ends of the spring are folded into a hook shape and hooked on the force pull ring 4-1.

[0036] In this embodiment, when uneven settlement occurs in the monitoring area, the settlement bottom plate 1-1 will tilt, and the two springs will be subjected to inconsistent forces, so the supporting beam 2 will undergo uneven deformation, which will be transmitted to the fiber grating 3. The specific situation of the uneven settlement can be calculated by back-calculation through material mechanics methods. Therefore, this device can also monitor the uneven settlement of the observation point.

[0037] Furthermore, in order to facilitate the burial of the sedimentation meter inside the foundation structure, the sedimentation meter housing 1 described in this embodiment is a cylindrical structure, and also has a top cover 1-2 and a circular sleeve 1-3. The top cover 1-2 is arranged at the upper port of the circular sleeve 1-3 and is sealed with the circular sleeve 1-3; the sedimentation bottom plate 1-1 is arranged in the lower port of the circular sleeve 1-3 and is gap-fitted with the inner wall of the circular sleeve 1-3.

[0038] Among them, the outer diameter of the top cover 1-2 is greater than the inner diameter of the circular sleeve 1-3, preferably equal to the outer diameter of the circular sleeve 1-3 at the upper end, and the top cover 1-2 is buckled at the upper end of the circular sleeve 1-3 and is detachably sealed and connected; specifically, a plurality of threaded holes are evenly opened in the circumferential direction at the position near the edge of the top cover 1-2, and a plurality of threaded holes are evenly opened in the circumferential direction at the upper end of the circular sleeve 1-3, and are arranged one by one with the threaded holes on the top cover 1-2, and the top cover 1-2 and the circular sleeve 1-3 are fixedly connected by screws. Moreover, in order to better achieve sealing performance, sealing members such as rubber pads can also be arranged between the top cover 1-2 and the circular sleeve 1-3, and coated with sealant to ensure that the structure is waterproof. In addition, the thickness of the top cover 1-2 can be adjusted according to actual monitoring needs. For example, if it is located in a watery and heavy-loaded area, the thickness of the top cover 1-2 can be increased, and vice versa.

[0039] In this embodiment, the top cover 1-2 and the circular sleeve 1-3 are detachably connected, which facilitates the installation and replacement of the top cover 1-2 and the internal measuring elements. At the same time, a sealed connection is adopted to avoid the influence of external environmental factors, which may lead to poor measurement accuracy.

[0040] Among them, in order to facilitate the installation of the supporting beam 2, an annular bearing platform 1-3-1 is coaxially arranged in the circular sleeve 1-3 described in this embodiment, and the two ends of the supporting beam 2 in the length direction are respectively mounted on the annular bearing platform 1-3-1 and fixed by screws to realize the installation between the supporting beam 2 and the sedimentation meter housing 1. The annular bearing platform 1-3-1 in this embodiment can be obtained by installing a separate, rigid annular structure in the circular sleeve 1-3, that is, the annular structure is coaxially inserted into the circular sleeve 1-3 from the upper port of the circular sleeve 1-3, and the annular structure is fixedly connected to the circular sleeve 1-3 as a whole by screws; it can also be obtained by directly processing the annular structure at the middle position in the circular sleeve 1-3; it can also be obtained by the variable cross-section structure inside the circular sleeve 1-3. Specifically, when processing the circular sleeve 1-3, the inner diameter of the upper half of the circular sleeve 1-3 is greater than the inner diameter of the lower half, so that an annular step is formed in the middle position of the circular sleeve 1-3, and this annular step is the annular bearing platform 1-3-1.

[0041] In addition, in order to transmit the signal measured by the fiber Bragg grating 3 to the demodulator outside the sedimentation meter, a lead hole 1-3-2 is opened on the side wall of the circular sleeve 1-3 in this embodiment, and the optical fiber connected to the fiber Bragg grating 3 passes through the lead hole 1-3-2 and is connected to the signal input end of the demodulator; wherein, the lead hole 1-3-2 is sealed with rubber after the fiber Bragg grating wire is led out to achieve waterproofing.

[0042] In addition, in order to enable the sedimentation meter to be mounted at the original geological location, a mounting surface 1-3-3 is provided on the outside of the circular sleeve 1-3 in this embodiment, and the sedimentation meter is mounted at the original geological location via the mounting surface 1-3-3. The mounting surface 1-3-3 in this embodiment can be a continuous annular surface or a combination. When the carrying surface 1-3-3 is an annular surface, it can be obtained by installing a separate, rigid annular structure outside the circular sleeve 1-3, that is, the annular structure is sleeved outside the circular sleeve 1-3, and the annular structure and the circular sleeve 1-3 are fixedly connected as a whole by screws, and the lower surface of the annular structure is the carrying surface 1-3-3; the annular structure can also be directly processed at the middle position outside the circular sleeve 1-3, and similarly, the lower surface of the annular structure is the carrying surface 1-3-3; it can also be obtained by a variable cross-section structure outside the circular sleeve 1-3. Specifically, when processing the circular sleeve 1-3, the outer diameter of the upper half of the circular sleeve 1-3 is greater than the outer diameter of the lower half, so that an annular step is formed in the middle position of the circular sleeve 1-3, and the surface of this annular step is the carrying surface 1-3-3. When the carrying surface 1-3-3 is a combined form, a plurality of support plates can be evenly arranged on the outer wall of the circular sleeve 1-3 along the circumferential direction, and the lower surface of the support plate is the carrying surface 1-3-3.

[0043] During the specific installation of this embodiment, the core is taken inside the foundation structure, and the settlement meter is carried to the original geology through the carrying surface 1-3-3. The part below the carrying surface 1-3-3 is detected at the monitoring point. At this time, the settlement bottom plate 1-1 is in contact with the bottom of the monitoring point and is in a horizontal state, and the spring is in a stretched or naturally straightened state; after the installation and fixation are completed, the original geological soil is used for backfilling and compaction. At this time, the relative settlement of the original geology and the observation point can be monitored. Among them, the height of the circular sleeve 1-3 can be determined according to the coring depth of the road and the settlement range of the observation point. If the coring depth is large and the soil at the monitoring location is prone to large settlement, the axial height of the circular sleeve 1-3 can be appropriately increased to improve the monitoring range and accuracy.

[0044] Wherein, in order to ensure that the sedimentation bottom plate 1-1 can move in the vertical direction and deflect in the horizontal direction, the outer diameter of the sedimentation bottom plate 1-1 is smaller than the inner diameter of the circular sleeve 1-3, and the gap between the sedimentation bottom plate 1-1 and the circular sleeve 1-3 is filled with soft sealant to ensure that the inside of the sedimentation meter is in a relatively sealed state, and because the sealant material is soft and changeable, it does not affect the movement and deflection of the sedimentation bottom plate. In addition, the thickness of the sedimentation bottom plate 1-1 should be adjusted according to the demand of the monitoring range, and can be estimated according to the stiffness coefficient k of the spring. The sedimentation monitoring range x=G / 2k, G is the gravity of the sedimentation bottom plate, when the settlement amount in the observation area is large, the thickness of the sedimentation bottom plate 1-1 can be increased to increase weight, or reduce the stiffness of the spring, but considering that in order to avoid the phenomenon of spring failure due to excessive deformation, it is recommended to adjust the range of the sedimentation meter only by adjusting the weight of the sedimentation bottom plate 1-1, and vice versa for small ranges. In addition, the increase in the thickness of the sedimentation bottom plate 1-1 can ensure that the interior of the sedimentometer remains in a relatively sealed state during the sedimentation process.

[0045] Furthermore, in order to keep the deformation of the key monitoring points of the fiber Bragg grating 3 consistent and thus avoid the chirping phenomenon, the supporting beam 2 described in this embodiment is a variable cross-section beam, and the cross-section gradually decreases along the length direction.

[0046] The thickness of the variable cross-section beam can be adjusted according to different use conditions. For example, when the measured area is a non-stressed area, the geology is uniform and only a small settlement occurs, the thickness of the variable cross-section beam should be reduced to increase the actual sensitivity and resolution of the settlement meter, and vice versa. In addition, the material of the variable cross-section beam should usually be a material with good toughness. In this embodiment, spring steel is used. In the implementation process, other materials or other forms of structures can also be used as long as the deformation function can be achieved. The essence is no different from this example.

[0047] This embodiment changes the cross-sectional stiffness of the supporting beam 2 to keep the deformation of the key monitoring points of the fiber Bragg Bragg grating 3 consistent, so that the relative drift of the Bragg reflection wavelength at different positions on the fiber Bragg grating is the same, and the half-width of the reflection spectrum is stable, thereby avoiding the chirp phenomenon (the fiber Bragg grating chirp effect refers to the fact that when light passes through the fiber Bragg grating, due to the existence of tiny periodic changes in the grating, the frequency of the light changes, which in turn causes the light frequency deviation, resulting in frequency shift or chirp. If the deformation is inconsistent, different grids of the grating will have different widths, and then the refractive index change will be different, the periodicity and frequency of the light will change, causing chirp), and the signal is stable.

[0048] Furthermore, in order to avoid the measurement error of the sedimentometer caused by temperature, two fiber Bragg gratings 3 are arranged in this embodiment, and are arranged respectively on the upper surface and the lower surface of the supporting beam 2, wherein the fiber Bragg grating 3 is mounted on the supporting beam 2 by pasting. In addition, each fiber Bragg grating 3 is connected to a wire for signal transmission.

[0049] In this embodiment, since the fiber Bragg grating 3 is sensitive to both temperature and force, according to material mechanics, the support beam 2 bends downward under the action of the spring tension. At this time, the upper surface of the support beam 2 is compressed, and the lower surface of the support beam 2 is tensile, and the tension and pressure are the same; in order to distinguish the two fiber Bragg gratings 3 on the upper and lower surfaces of the support beam 2, in this embodiment, the fiber Bragg grating 3 on the upper surface of the support beam 2 is called the compressed fiber Bragg grating, and the fiber Bragg grating 3 on the lower surface of the support beam 2 is called the tensile fiber Bragg grating. Among them, the wavelength of the compressed fiber Bragg grating will decrease after being compressed, and the observed wavelength signal actually reflects temperature-force (assuming that the temperature rises); the wavelength of the tensile fiber Bragg grating will increase after being tensile, and the observed wavelength signal actually reflects temperature+force. Therefore, after the two wavelength signals are decoupled, the influence of temperature can be eliminated, avoiding the measurement error of the sedimentometer caused by temperature (thermal expansion and contraction), and ensuring the measurement accuracy.

[0050] The following is a further description of the manufacturing process, installation process and working process of the utility model to further demonstrate the working principle and advantages of the utility model:

[0051] 1. Production and installation process of sedimentation meter:

[0052] Step 1, making a sedimentation meter housing 1 and a variable-section beam, wherein the sedimentation meter housing 1 and the variable-section beam can be completed by welding, rolling or 3D printing technology, and the sedimentation meter housing 1 has corrosion resistance and good anti-deformation characteristics; and the variable-section beam has the ability of elastic deformation and rebound, preferably using a spring steel plate, the thickness of which is set to 5mm, to meet the strength and rebound performance requirements in the actual test process, after the deformation disappears, it can be restored to the stage before deformation, ensuring that the variable-section beam is in the elastic stage during the entire deformation process, and no plastic deformation occurs;

[0053] Step 2, the fiber Bragg grating 3 is pasted on the processed variable cross-section beam by using a special adhesive. When pasting, it is necessary to keep the thickness of the adhesive uniform to avoid causing too large a structural change to the original variable cross-section beam, and try to avoid bubbles in the packaging adhesive at the fiber Bragg grating, otherwise it is easy to cause a multi-peak phenomenon of the sensor;

[0054] Step 3, connect two springs to the hooks of the variable cross-section beam and the settlement bottom plate 1-1;

[0055] Step 4, coring inside the original compacted infrastructure (structures such as roads, bridges, tunnels, etc.), the coring height is slightly higher than the height of the narrow diameter part of the circular sleeve 1-3, the coring hole is cleaned, the loose soil is cleaned out, and the original soil is used for backfilling and leveling, and the backfill thickness allows the sedimentation meter to be properly placed inside the hole; wherein the inner diameter of the hole is larger than the outer diameter of the circular sleeve 1-3, and smaller than the outer diameter of the carrying surface 1-3-3; the depth of the hole is equal to the distance between the carrying surface 1-3-3 and the bottom end of the circular sleeve 1-3;

[0056] Step 5, insert the circular sleeve 1-3 into the hole, and carry the circular sleeve 1-3 to the original geological location through the carrying surface 1-3-3, and the part below the carrying surface 1-3-3 is probed to the monitoring point; place the connector of the variable-section beam, the spring and the settlement bottom plate 1-1 into the sleeve through the upper port of the circular sleeve 1-3, and the settlement bottom plate 1-1 slowly slides down along the inner wall of the circular sleeve 1-3 to the bottom of the hole, and the two ends of the variable-section beam are horizontally carried on the annular bearing platform 1-3-1 along the radial direction of the circular sleeve 1-3 and fixed by screws. At this time, the spring is in a stretched or naturally straightened state;

[0057] Step 6, the optical fiber of the fiber Bragg grating 3 is passed through the lead hole 1-3-2, the lead hole 1-3-2 is sealed with rubber, and the lead optical fiber is encapsulated and protected with protective measures such as armored wire, and then the lead optical fiber is connected to the optical fiber connector using an optical fiber fusion splicer to facilitate the connection between the sensor and the demodulator;

[0058] Step 7, the top cover of the sedimentation meter is sealed and connected to the circular sleeve 1-3 by bolts and rubber pads, and the sealing part is waterproofed again with a sealing colloid. After the glue is cured, the upper part of the sedimentation meter is buried and compacted with the original soil.

[0059] 2. Working process of sedimentation meter:

[0060] After the installation of the settlement meter is completed, the initial fiber grating wavelength data is recorded (it should be noted that before monitoring, an indoor calibration test should be carried out to quantify the relationship between the spring deformation and the fiber deformation, and it can also be analyzed theoretically and calculated through the material mechanics deformation formula); when settlement occurs in the monitoring area, the settlement bottom plate 1-1 moves downward under the action of its own gravity, and the spring is subjected to tension and transmitted to the variable-section beam. Through the coordinated deformation between the fiber grating 3 and the variable-section beam, the fiber grating 3 arranged on the surface of the variable-section beam is deformed, the grating pitch becomes larger, and then the optical signal changes. The optical signal is transmitted to the demodulator and the terminal processing equipment, and the relationship between the optical signal change and the settlement amount is established through the indoor calibration test relationship, thereby monitoring the foundation settlement.

[0061] Through the two fiber gratings attached to the upper and lower surfaces of the variable cross-section beam, the beam body produces different deformations when subjected to force. The difference in deformation can be used to calculate the effect of temperature on the deformation of the fiber grating, and then temperature compensation can be achieved, so that the amount of settlement can be accurately obtained. In addition, if uneven settlement occurs at the monitoring point, the settlement bottom plate will tilt, and then the forces on the two springs will be inconsistent, and the variable cross-section beam will undergo uneven deformation, which will be transmitted to the fiber grating. The specific situation of uneven settlement can be calculated by back-calculation through material mechanics methods. Therefore, this device can also monitor uneven settlement at the observation point.

[0062] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments, and other arrangements may be designed without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the features described in the various dependent claims and herein may be combined in a manner different from that described in the original claims. It may also be understood that the features described in conjunction with the individual embodiments may be used in other described embodiments.

Claims

1. A road settlement meter based on optical fiber technology, characterized in that: The invention comprises a sedimentation meter housing (1), a supporting crossbeam (2), a fiber Bragg grating (3) and a connecting piece (4); the sedimentation meter housing (1) has a sedimentation bottom plate (1-1) which can move in a vertical direction and deflect in a horizontal direction; the supporting crossbeam (2) is a long strip structure with elastic deformation and rebound capabilities; the supporting crossbeam (2) is horizontally installed in the sedimentation meter housing (1) and is located on an extension surface of a central plane of the sedimentation bottom plate (1-1); the supporting crossbeam (2) and the sedimentation bottom plate (1-1) are connected by a connecting piece (4); the fiber Bragg grating (3) is centrally arranged on the supporting crossbeam (2), and the length direction of the fiber Bragg grating (3) is consistent with the length direction of the supporting crossbeam (2).

2. A road settlement meter based on optical fiber technology according to claim 1, characterized in that: The connecting members (4) are two elastic connecting members arranged along the length direction of the supporting crossbeam (2) and symmetrically on both sides of the optical fiber grating (3), and the stretching direction of each elastic connecting member is a vertical direction.

3. A road settlement meter based on optical fiber technology according to claim 1 or 2, characterized in that: The sedimentation meter housing (1) also comprises a top cover (1-2) and a circular sleeve (1-3); the top cover (1-2) is arranged at the upper port of the circular sleeve (1-3) and seals the upper port of the circular sleeve (1-3); the sedimentation bottom plate (1-1) is arranged in the lower port of the circular sleeve (1-3) and is clearance-matched with the inner wall of the circular sleeve (1-3).

4. A road settlement meter based on optical fiber technology according to claim 3, characterized in that: The top cover (1-2) is buckled on the upper end of the circular sleeve (1-3) and fixedly connected by screws.

5. A road settlement meter based on optical fiber technology according to claim 4, characterized in that: A sealing gasket is provided between the top cover (1-2) and the circular sleeve (1-3).

6. A road settlement meter based on optical fiber technology according to claim 3, characterized in that: An annular bearing platform (1-3-1) is coaxially arranged inside the circular sleeve (1-3), and both ends of the supporting crossbeam (2) in the length direction are respectively mounted on the annular bearing platform (1-3-1) and fixed by screws.

7. A road settlement meter based on optical fiber technology according to claim 3, characterized in that: A lead hole (1-3-2) is provided on the side wall of the circular sleeve (1-3). The optical fiber of the fiber grating (3) passes through the lead hole (1-3-2) and is connected to the signal input end of the demodulator. The lead hole (1-3-2) is sealed.

8. A road settlement meter based on optical fiber technology according to claim 3, characterized in that: The outside of the circular sleeve (1-3) is provided with a mounting surface (1-3-3).

9. A road settlement meter based on optical fiber technology according to claim 1 or 2, characterized in that: The supporting cross beam (2) is a variable cross-section beam, and the cross-section gradually decreases along the length direction.

10. A road settlement meter based on optical fiber technology according to claim 1 or 2, characterized in that: Two optical fiber gratings (3) are arranged, and are respectively arranged on the upper surface and the lower surface of the supporting crossbeam (2).

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