An experimental device based on FBG to monitor the strain and temperature of anti-slide piles

Abstract

The present invention discloses an experimental device for monitoring the strain and temperature of anti-slip piles based on fiber optic sensing (FBG). This device belongs to the field of fiber optic sensing monitoring technology and includes a simulated slope, a loading system, a strain and temperature monitoring system, a pressure sensor, and a data processing system. The simulated slope is embedded with anti-slip piles. The loading system is used to apply horizontal or vertical loads to the anti-slip piles within the simulated slope. The strain and temperature monitoring system includes FBG strain and temperature sensing fibers distributed on the steel bars within the anti-slip piles, and the pressure sensor is mounted on the anti-slip piles. The data processing system integrates the signals collected by the FBG strain and temperature sensing fibers, demodulates the corresponding strain and temperature information using an FBG data demodulator, and compares and verifies the corresponding strain and temperature information with the strain and temperature information obtained by the pressure sensor, thereby evaluating the status of the anti-slip piles. The present invention can monitor the structural integrity, slippage of the anti-slip piles, and the stability of the surrounding soil in real time.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensing monitoring, and in particular relates to an experimental device for monitoring the strain and temperature of an anti-slip pile based on FBG. Background Art

[0002] Slope hazards refer to natural disasters and engineering problems caused by slope instability. Specifically, slope instability can lead to serious consequences, such as landslides, where large amounts of soil slide downward along a sliding surface, causing massive damage; debris flows, where large amounts of mud, rock, and water create a highly destructive fluid; and even ground subsidence, causing serious economic and social problems. To reduce slope hazards, effective engineering measures are needed for prevention and control, such as anti-slide piles, anchoring, drainage, and vegetation cover. Anti-slide piles are a common slope stabilization measure. Compared to other methods, their advantage lies in their ability to support unstable slopes and prevent them from sliding due to gravity or other factors. By driving anti-slide piles into the slope, they increase the resistance of the sliding surface, thereby improving the stability of the entire slope. Furthermore, anti-slide piles are easy to install and cost-effective, allowing for widespread use. Through systematic and scientific deployment, they can effectively stabilize slopes. Once installed, they can maintain slope stability for an extended period of time. In emergency situations, anti-slide piles are also a quick, immediate response measure.

[0003] Monitoring the long-term structural integrity and slippage of anti-slip piles within slopes, as well as the impact on the stability of the surrounding soil, is crucial. However, existing devices are not able to effectively monitor the health of anti-slip piles. For example, the integrated equipment is expensive, has poor anti-interference capabilities, and is not very accurate. Therefore, providing a low-cost, anti-interference, and highly accurate experimental device is a pressing technical challenge for those skilled in the art. Summary of the Invention

[0004] Based on the problems existing in the existing technology, the present invention proposes an experimental device based on FBG to monitor the strain and temperature of anti-slip piles to solve the problems existing in the above-mentioned existing technology, and can monitor the structural integrity, slippage situation and stability of the surrounding soil of the anti-slip piles in real time.

[0005] In order to achieve the above-mentioned objectives, the present invention adopts the following technical solutions: an experimental device based on FBG for monitoring the strain and temperature of anti-slip piles includes a simulated slope, a loading system, a strain and temperature monitoring system, a pressure sensor and a data processing system; anti-slip piles are embedded in the simulated slope, the loading system is used to apply horizontal loads or vertical loads to the anti-slip piles in the simulated slope, the strain and temperature monitoring system includes FBG strain and temperature sensing optical fibers distributed on the steel bars in the anti-slip piles, the pressure sensor is arranged on the anti-slip piles, and the data processing system can integrate the signals collected by the FBG strain and temperature sensing optical fibers, and demodulate the corresponding strain and temperature information through the FBG data demodulation instrument, and compare and verify it with the strain and temperature information obtained by the pressure sensor, so as to evaluate the status of the anti-slip piles.

[0006] Furthermore, the experimental device for monitoring the strain and temperature of the anti-slip pile based on FBG also includes a monitoring system, which is a motion camera used to record the tiny deformation and deformation time during the experiment.

[0007] Preferably, the simulated slope in the experimental setup for monitoring the strain and temperature of anti-slip piles using FBGs comprises an external box and a soil layer filled within it. The external box comprises an internally interconnected rectangular parallelepiped box and two rectangular trapezoidal boxes, the inclined surfaces of which form the slope of the simulated slope. The inner wall of the box is fixed, while the outer wall slides in response to the stepwise application of horizontal or vertical loads by the loading system, reflecting the impact of different load states on the health of the anti-slip piles. The outer wall is provided with support points, and the external load application process is achieved by the extension and retraction of hydraulic cylinders.

[0008] Preferably, the rear side of the external box is fixedly connected to a simulated precipitation component, and the simulated precipitation component includes a first gear, one side of the first gear is movably connected to the external box through a bearing, the surface of the first gear is fixedly connected to a fastener, the surface of the fastener is sleeved with a connecting frame, the top of the connecting frame is fixedly connected to a mounting frame, the bottom of the mounting frame is movably connected to a spray pipe through a bearing, the bottom of the spray pipe is connected to a spray head, one side of the spray pipe passes through one side of the connecting frame and extends to the outside of the connecting frame, one side of the spray pipe is connected to a joint, one side of the rear end of the external box is movably connected to a second gear through a bearing, the second gear is meshed with the first gear, a motor is provided on the surface of the second gear, the output end of the motor is fixedly connected to the second gear, and the bottom of the inner cavity of the external box is fixedly connected to a water pressure gauge.

[0009] Precipitation processes of varying intensity and duration were simulated to investigate their effects on anti-slip pile strain, temperature, and simulated slope stability. By adjusting the intensity and duration of precipitation, the mechanical responses of the anti-slip piles under various conditions, such as saturation and wet-dry cycles, were observed. This provided data support for analyzing the reliability of anti-slip piles in responding to precipitation in actual projects, making the experimental results more realistic for real-world engineering scenarios. The water pressure gauge measured the water pressure within the sand at different times.

[0010] Furthermore, counterweights are fixedly connected to both sides of the bottom of the spray pipe, and the counterweights ensure that the nozzle is always in a vertical state with the spray pipe when the angle changes. By setting the counterweight at the bottom of the spray pipe, the nozzle can be made vertical. During the spraying process, the nozzle is always in a downward spraying effect.

[0011] Preferably, a reinforcement plate is fixedly connected to one side of the motor, and one side of the reinforcement plate is fixedly connected to the external box body. The motor is installed through the reinforcement plate, thereby ensuring the stability of the motor installation.

[0012] Preferably, the outer wall of the external box body includes a first movable plate, a second movable plate is provided on one side of the first movable plate, and the first movable plate and the second movable plate are fixedly connected to the opposite side with a connecting plate, and the top and bottom of the surface of the connecting plate are provided with positioning components. The external box body is divided into two parts and is reinforced by the positioning component, which can achieve the purpose of convenient disassembly and assembly, and can also perform loading effects in different positions according to experimental requirements.

[0013] Preferably, the positioning assembly includes a housing, the housing being arranged on the surface of the connecting plate, the inner cavity of the housing being threadedly connected to a threaded rod, one side of the threaded rod extending through the exterior of the housing and being movably connected to a first limiting plate via a bearing, and one side of the housing being fixedly connected to a second limiting plate. Furthermore, the top and bottom sides of the connecting plate are each provided with a limiting groove for use with the first limiting plate and the second limiting plate, one side of the first limiting plate and one side of the second limiting plate both extending into the inner cavity of the limiting groove. By providing the positioning assembly, the first movable plate and the second movable plate can be connected to form an integral structure, while also being able to achieve a separation effect. By rotating the threaded rod, the threaded rod drives the first limiting plate to move, and the first limiting plate is disengaged from the inner cavity of the limiting groove, thereby enabling the housing of the fixed connecting plate to be removed, making the first movable plate and the second movable plate independent of each other. The hydraulic cylinder is provided in two groups, and under the action of the hydraulic cylinder, different forms of loads can be stably applied to the simulated slope and the anti-slip pile.

[0014] Furthermore, one side of the hydraulic cylinder is movably connected to a connecting seat via a rotating shaft, one side of the connecting seat is fixedly connected to a fixing plate, and the side of the fixing plate away from the connecting seat is fixedly connected to the outer wall of the external box body via bolts. One side of the hydraulic cylinder is connected to the fixing seat via the connecting seat, and one side of the fixing seat is fixedly connected to the outer wall of the external box body, which can support the external box body, thereby improving the supporting effect of the hydraulic cylinder.

[0015] Preferably, three anti-slip piles of different sizes are distributed in the simulated slope, and each anti-slip pile is provided with a pressure sensor and an FBG strain and temperature sensing optical fiber.

[0016] Compared with the prior art, the advantages and positive effects of the experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG of the present invention are:

[0017] 1. The experimental device of the present invention for monitoring the strain and temperature of anti-slip piles based on FBG can help researchers to more conveniently monitor the structural integrity, slippage and stability of the surrounding soil of the anti-slip piles in real time. Anti-slip piles are an engineering structural measure used to prevent soil landslides and stabilize slopes. In the design of anti-slip piles, monitoring equipment can be installed to provide early warnings for possible landslides by monitoring changes in pile body stress and temperature. The present invention can simulate the impact on anti-slip piles in engineering applications and monitor them in real time, giving timely early warnings. This FBG-based monitoring technology has high sensitivity and strong anti-interference ability. Multiple FBG sensors can be arranged on an optical fiber to achieve distributed measurement of different parts of the anti-slip piles. The other components used in the device are replaceable. It is a low-cost, high-efficiency, and highly operable experimental device.

[0018] 2. The experimental setup for monitoring the strain and temperature of anti-slide piles using FBGs provides a bearing foundation for anti-slide piles that closely resembles actual engineering environments. It simulates the mechanical response of slopes in their natural state and under external forces, ensuring that the forces and deformations experienced by the anti-slide piles in this simulated environment are similar to those in actual conditions. This allows for accurate study of the mechanism of action of anti-slide piles in slopes, precisely simulating actual slope geological conditions, and ensuring that experimental results truly reflect the mechanical behavior of anti-slide piles in various complex slopes. Different soil structures and slope settings help researchers gain a comprehensive understanding of anti-slide pile performance, providing a reliable reference for practical engineering design and improving the stability and reliability of anti-slide piles in practical applications. Specific rock and soil material ratios and shaping can simulate slopes of varying geological origins, such as weathered rock slopes and deposited soil slopes, enabling the identification of optimal anti-slide pile designs for different slope types and reducing the risk of anti-slide pile failure due to complex slope conditions in actual projects.

[0019] 3. The present invention's experimental device for monitoring the strain and temperature of anti-slide piles using FBGs applies loads of varying types and magnitudes to simulate various external forces that may be experienced in real-world projects, such as deadweight, earthquake forces, and loads from superstructures. Precise control of the loading process facilitates investigation of the strain and temperature variations of anti-slide piles under varying load conditions, providing data support for evaluating the piles' bearing capacity and stability. Diverse loading methods and precise control capabilities enable experiments to simulate complex, real-world load conditions. Researchers can systematically study the mechanical response of anti-slide piles under different load combinations and conduct in-depth analysis of their bearing limits and stability boundaries. This is crucial for optimizing anti-slide pile design parameters and improving their safety under extreme loads. For example, simulating earthquake loading can be used to study the seismic performance of anti-slide piles in earthquake-prone regions, providing targeted guidance for anti-slide pile design in these areas and enhancing their anti-slide capabilities under extreme conditions such as earthquakes, thereby ensuring project safety.

[0020] 4. The data processing system in the experimental setup for monitoring the strain and temperature of anti-slip piles using FBGs performs real-time processing and analysis of the collected data. This system displays the strain, temperature, and pressure changes of the anti-slip piles in real time in intuitive graphical form, allowing experimenters to quickly understand experimental progress and data trends. Furthermore, through in-depth data analysis, such as statistical analysis and curve fitting, the underlying patterns are uncovered, providing strong support for studying the mechanical behavior and design optimization of anti-slip piles. The data processing system enables efficient management and in-depth analysis of experimental data. The real-time display function facilitates timely adjustment of experimental parameters, ensuring experimental accuracy and effectiveness. Data mining and analysis can reveal the mechanical behavior patterns of anti-slip piles, supporting the development of precise mechanical models and guiding actual engineering design and construction. Statistical analysis of large amounts of experimental data can identify key performance indicators of anti-slip piles under different conditions, providing a quantitative basis for the selection and design of anti-slip piles in actual projects, thereby improving project quality and safety.

[0021] 5. The precipitation simulation component in the experimental setup for monitoring the strain and temperature of anti-slip piles using FBGs allows the experiment to fully consider the impact of precipitation on the piles. Simulating precipitation of varying intensities and durations helps researchers gain a deeper understanding of the mechanical properties of anti-slip piles under various precipitation conditions, providing a basis for developing maintenance strategies for anti-slip piles during rainy seasons or in humid areas. By simulating prolonged periods of heavy precipitation, the long-term impermeability and stability of the piles can be studied, providing a reference for waterproofing and anti-corrosion treatment of the piles in actual projects, thereby improving the durability and reliability of the piles in precipitation environments and extending their service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG in the present invention;

[0023] Figure 2 Schematic diagram of the distribution structure of the steel cage and FBG strain and temperature sensing optical fiber on the steel cage in the present invention;

[0024] Figure 3 This is a principle block diagram of the vibrating wire earth pressure sensor of the present invention;

[0025] Figure 4 The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG in the present invention Figure 2 A local enlarged schematic diagram of point A;

[0026] Figure 5 Schematic diagram of the positioning component in the experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG in the present invention;

[0027] Figure 6 The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG in the present invention Figure 5 A local enlarged schematic diagram of point B;

[0028] Figure 7 This is a three-dimensional structural diagram of the precipitation simulation component in the experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG in the present invention.

[0029] Explanation of reference numerals in the accompanying drawings: 1. simulated slope; 2. loading system; 3. strain and temperature monitoring system; 4. monitoring system; 5. data processing system; 6. anti-slip pile; 7. supporting steel bar; 8. steel bar ring; 9. FBG strain and temperature sensing optical fiber; 10. pressure sensor; 11. slide rail; 12. rotating ball; 13. first gear; 14. fastener; 15. connecting frame; 16. mounting frame; 17. spray pipe; 18. spray head; 19. Connector; 20. Second gear; 21. Motor; 22. Water pressure gauge; 23. Counterweight; 24. Reinforcement plate; 25. First movable plate; 26. Second movable plate; 27. Connecting plate; 28. Housing; 29. Threaded rod; 30. First limiting plate; 31. Second limiting plate; 32. Limiting groove; 33. Connecting seat; 34. Fixed plate; 35. Support plate; 36. Bottom plate; 37. Drain pipe; 38. Slot; 39. Clamping block. DETAILED DESCRIPTION

[0030] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] like Figure 1-Figure 7 As shown, the present invention provides an experimental device for monitoring the strain and temperature of anti-slip piles based on FBG (fiber Bragg grating), which includes a simulated slope 1, a loading system 2, a strain and temperature monitoring system 3, a pressure sensor 10 and a data processing system 5; wherein, anti-slip piles 6 are embedded in the simulated slope 1, the loading system 2 is used to apply horizontal loads or vertical loads to the anti-slip piles 6 in the simulated slope 1, the strain and temperature monitoring system 3 includes FBG strain and temperature sensing optical fibers 9 distributed on the steel bars in the anti-slip piles 6, the pressure sensor 10 is arranged on the anti-slip piles 6, and the data processing system 5 can integrate the signals collected by the FBG strain and temperature sensing optical fibers 9, and demodulate the corresponding strain and temperature information through the FBG data demodulation instrument, and compare and verify it with the strain and temperature information obtained by the pressure sensor 10, so as to evaluate the status of the anti-slip piles 6.

[0033] In one embodiment, the experimental apparatus for monitoring the strain and temperature of anti-slip piles using FBGs also includes a monitoring system 4, a motion camera used to record minute deformations and their duration during the experiment. The simulated slope 1 includes an external box and a soil layer filled within it. The external box comprises an internally interconnected rectangular parallelepiped box and two right-angled trapezoidal boxes, the inclined surfaces of which form the slope of the simulated slope 1. The inner wall of the box is fixed, while the outer wall can slide in response to step-by-step loading by the loading system 2, reflecting the impact of different load states on the health of the anti-slip piles 6. The outer wall is provided with a support point, and the load application process of the box body is realized by the expansion and contraction of the hydraulic cylinder. Three anti-slip piles 6 of different sizes are distributed in the simulated slope 1. Each anti-slip pile 6 is provided with a pressure sensor 10 and an FBG strain and temperature sensing optical fiber 9. The pressure sensor 10 is a vibrating wire earth pressure sensor 10. The anti-slip pile 6 is made of a steel cage and concrete. The steel cage includes four supporting steel bars 7 and steel rings 8. The four supporting steel bars 7 are arranged vertically and distributed in a rectangular shape. The four supporting steel bars 7 are connected with multiple vertically distributed steel bars. A rectangular steel ring 8 is provided, and four corners of the steel ring 8 are connected to four supporting steel bars 7 respectively. The positions where FBG strain and temperature sensing optical fibers 9 need to be arranged are on the steel bars constituting the supporting steel bars 7 or the steel ring 8. A groove is opened downward on the surface of the steel bar along the length direction of the steel bar. The FBG strain and temperature sensing optical fibers 9 are arranged in the groove and pasted in the groove. The loading system 2 is a hydraulic cylinder. The outer wall of the box can slide under the load force provided by the hydraulic cylinder to simulate the stress state of the anti-slip pile 6 under the predetermined conditions.

[0034] Utilizing the aforementioned technical solution, fiber-optic strain and temperature sensors utilize fiber optic technology to measure strain and temperature. Fiber Bragg gratings (FBGs) within the fiber measure the wavelength of light at specific wavelengths. When measuring strain, the Bragg wavelength shifts when the fiber is stretched or compressed. By measuring this wavelength shift, the strain magnitude can be calculated. When measuring temperature, thermal expansion or changes in the refractive index of the fiber due to temperature changes also cause changes in the Bragg wavelength. Through measurement calibration, it is possible to distinguish between wavelength shifts caused by strain and temperature.

[0035] The simulated slope 1 in the experimental setup for monitoring the strain and temperature of anti-slip piles using FBGs consists of an external box filled with soil layers, including soil, sand, and other desired soil layers. The external box comprises a rectangular box and two rectangular trapezoidal boxes, each connected to the other. The inclined surfaces of the two rectangular trapezoidal boxes form the slope of the simulated slope 1. The length, width, and height of the rectangular box are 1 x 1 x 2.5 cubic meters. The outer wall of the box can slide under the load of a hydraulic cylinder to simulate the stress state of the anti-slip pile 6 under predetermined conditions.

[0036] The pressure sensor 10 is a vibrating string earth pressure sensor 10. The vibrating string earth pressure sensor is a sensor used to measure the compressive stress of the soil inside the structure. The vibrating string earth pressure sensor is equipped with a built-in temperature sensor that can synchronously measure the temperature of the buried point. The function of measuring temperature is very important for improving the accuracy of the measurement, and it can perform temperature compensation to ensure the accuracy of the compressive stress data. During the operation of the vibrating string earth pressure sensor, the temperature data is recorded and analyzed together with the compressive stress data. The working principle block diagram of the vibrating string earth pressure sensor is shown in the figure below. Figure 3 As shown, the specific process is that the pressure sensor 10 is installed on the surface of the anti-slip pile 6 and buried in the designed model box together with the anti-slip pile 6. After the loading device applies the load, the pressure sensor 10 on the surface of the anti-slip pile 6 senses the change in soil pressure, causing the sensor plate to deform. The sensor plate is the direct force-bearing component of the soil pressure sensor. When the soil pressure changes, the sensor plate will synchronously sense this change and deform. The deformation of the sensor plate is transmitted to the vibrating wire, causing the tension of the vibrating wire to change. The vibration frequency of the vibrating wire is closely related to its tension. Therefore, changes in soil pressure will directly cause changes in the vibration frequency of the vibrating wire. The excitation system excites the vibrating wire through devices such as electromagnetic coils to generate vibrations. The soil pressure is calculated by measuring the change in the vibration frequency of the vibrating wire. The change in the vibration frequency of the vibrating wire corresponds to the magnitude of the force. The vibration frequency signal of the vibrating wire is transmitted to a reading device or a data acquisition device. The vibrating wire soil pressure sensor can also synchronously measure the temperature value of the buried point, providing a more comprehensive basis for data analysis.

[0037] In addition, a simulated precipitation component is fixedly connected to the rear side of the external box, and the simulated precipitation component includes a first gear 13, one side of the first gear 13 is movably connected to the external box through a bearing, a fastener 14 is fixedly connected to the surface of the first gear 13, and a connecting frame 15 is sleeved on the surface of the fastener 14, the top of the connecting frame 15 is fixedly connected to the mounting frame 16, and the bottom of the mounting frame 16 is movably connected to the spray pipe 17 through a bearing, and the bottom of the spray pipe 17 is connected to the nozzle 18, and one side of the spray pipe 17 passes through one side of the connecting frame 15 and extends to the outside of the connecting frame 15, and one side of the spray pipe 17 is connected to a joint 19, and one side of the rear end of the external box is movably connected to the second gear 20 through a bearing, and the second gear 20 is meshed with the first gear 13, and a motor 21 is provided on the surface of the second gear 20, and the output end of the motor 21 is fixedly connected to the second gear 20, and the bottom of the inner cavity of the external box is fixedly connected to a water pressure gauge 22, simulating precipitation processes of different intensities and durations, and studying the influence of precipitation on the strain and temperature of the anti-sliding pile 6 and the stability of the simulated slope 1. By adjusting the intensity and duration of precipitation, the mechanical response of the anti-slip pile 6 under different conditions such as saturation and dry-wet cycles can be observed, providing data support for analyzing the reliability of the anti-slip pile 6 in dealing with precipitation factors in actual engineering projects, making the experimental results closer to real engineering scenarios.

[0038] The adjustable precipitation simulation device allows the experiment to fully consider the impact of precipitation on anti-slip piles 6. Simulating different precipitation intensities and durations helps researchers gain a deeper understanding of the changes in the mechanical properties of anti-slip piles 6 under various precipitation conditions, providing a basis for formulating maintenance strategies for anti-slip piles 6 during rainy seasons or in humid areas. By simulating long periods of heavy precipitation, the long-term impermeability and stability of anti-slip piles 6 can be studied, providing a reference for waterproofing and anti-corrosion treatment of anti-slip piles 6 in actual projects, improving the durability and reliability of anti-slip piles 6 in precipitation environments and extending their service life.

[0039] Furthermore, counterweights 23 are fixedly connected to both sides of the bottom of the spray pipe 17. The counterweights 23 ensure that the nozzle 18 is always in a vertical state with the spray pipe 17 when the angle changes. By arranging the counterweights 23 at the bottom of the spray pipe 17, the nozzle 18 can be made vertical. During the spraying process, the nozzle 18 is always in a downward spraying effect.

[0040] Preferably, a reinforcement plate 24 is fixedly connected to one side of the motor 21 , and one side of the reinforcement plate 24 is fixedly connected to the external box body. The motor 21 is installed through the reinforcement plate 24 to ensure the stability of the installation of the motor 21 .

[0041] In another embodiment, the outer wall of the external box includes a first movable plate 25, a second movable plate 26 is provided on one side of the first movable plate 25, and a connecting plate 27 is fixedly connected to the opposite side of the first movable plate 25 and the second movable plate 26. Positioning components are provided on the top and bottom of the surface of the connecting plate 27. The external box is divided into two parts and is reinforced by the positioning component, which can achieve the purpose of convenient disassembly and assembly, and can also perform loading effects in different positions according to experimental requirements.

[0042] Furthermore, the positioning assembly includes a shell 28, which is arranged on the surface of the connecting plate 27. The inner cavity of the shell 28 is threadedly connected to a threaded rod 29. One side of the threaded rod 29 passes through the outside of the shell 28 and is movably connected to a first limit plate 30 through a bearing. One side of the shell 28 is fixedly connected to a second limit plate 31. The top and bottom of both sides of the connecting plate 27 are provided with limit grooves 32 used in conjunction with the first limit plate 30 and the second limit plate 31. One side of the first limit plate 30 and one side of the second limit plate 31 extend to the inner cavity of the limit groove 32.

[0043] By setting a positioning component, the first movable plate 25 and the second movable plate 26 can be connected so that they can form an integral structure, and at the same time, a separation effect can be achieved. By rotating the threaded rod 29, the threaded rod 29 drives the first limit plate 30 to move, and the first limit plate 30 is disengaged from the inner cavity of the limit groove 32, so that the outer shell 28 of the fixed connecting plate 27 can be removed, and the first movable plate 25 and the second movable plate 26 are independent of each other. The hydraulic cylinder is set into two groups, and under the action of the hydraulic cylinder, different forms of loads are stably applied to the simulated slope 1 and the anti-slip pile 6. The first movable plate 25 and the second movable plate 26 are slidably connected to the inner wall of the external box through the slide rail 11 and the rotating ball 12 respectively.

[0044] In addition, one side of the hydraulic cylinder is movably connected to a connecting seat 33 via a rotating shaft, one side of the connecting seat 33 is fixedly connected to a fixing plate 34, and the side of the fixing plate 34 away from the connecting seat 33 is fixedly connected to the outer wall of the external box through bolts.

[0045] In a preferred embodiment, one side of the hydraulic cylinder is connected to a fixed seat via a connecting seat 33. One side of the fixed seat is fixedly connected to the outer wall of the external box, which can support the external box, thereby improving the support effect of the hydraulic cylinder. Using the above technical solution, one side of the hydraulic cylinder is movably connected to a support plate 35 via a rotating shaft. The bottom of the support plate 35 is fixedly connected to a base plate 36. The four corners of the top of the base plate 36 are provided with mounting holes. The top of the base plate 36 is fixedly connected to a reinforcement seat. One side of the reinforcement seat is fixedly connected to the support plate 35. The support plate 35, base plate 36, and reinforcement seat are all made of high-strength steel, with sufficient rigidity and strength to withstand the huge reaction force generated during loading.

[0046] In addition, a drainage pipe 37 is connected to the bottom of one side of the external box body. The drainage pipes 37 are arranged at equal distances. The drainage pipes 37 can quickly discharge wastewater during the simulated precipitation process, thereby improving the drainage effect.

[0047] On the other hand, the inner cavity of the groove is provided with a card slot 38, and the FBG strain and temperature sensing optical fiber 9 is arranged in the inner cavity of the card slot 38. The surface of the card slot 38 is fixedly connected to a clamping block 39 by a spring, and the surface of the clamping block 39 is provided with a pulling block. The FBG strain and temperature sensing optical fiber 9 is installed inside the card slot 38, and the FBG strain and temperature sensing optical fiber 9 is limited by the clamping block 39, which can ensure the stability of the installation of the FBG strain and temperature sensing optical fiber 9.

[0048] Furthermore, strain and temperature are two important factors affecting the performance of the anti-slip pile 6 of the present invention. Strain directly reflects the deformation of the pile body after being subjected to stress. Excessive strain may damage the pile structure or cause failure upon reaching its bearing limit, leading to deformation and affecting its effectiveness in practical applications. Monitoring the stress distribution clearly demonstrates the stress distribution and changes within the anti-slip pile 6, which is crucial for evaluating the design rationality and stability of the anti-slip pile 6. Optical fiber is corrosion-resistant and can be used for a long time. Long-term strain monitoring helps understand the performance changes of the anti-slip pile 6 under long-term loads, such as creep and fatigue effects. Temperature changes can affect the properties of the materials used in the anti-slip pile 6, such as the strength and elastic modulus of steel and concrete, thereby affecting the load-bearing capacity and deformation characteristics of the anti-slip pile 6. Thermal expansion and contraction are also a major factor affecting the performance of the anti-slip pile 6. When the temperature rises, the pile body expands, which can cause additional strain and even cracks. When the temperature drops, the pile body contracts, causing stress redistribution within the pile body. Temperature changes also affect the performance of the sensor. Without temperature compensation, monitoring errors can occur, affecting the accurate assessment of the status of the anti-slip pile 6. Fiber Bragg Grating (FBG) strain and temperature sensors utilize fiber optic technology to measure strain and temperature. Their operating principle is based on a Bragg grating (FBG) in an optical fiber, which reflects light at specific wavelengths. Strain measurement: When the optical fiber is stretched or compressed, the Bragg wavelength shifts accordingly. Strain can be calculated by measuring this wavelength shift. Temperature measurement: Temperature changes cause thermal expansion or changes in the refractive index of the optical fiber, which also shifts the Bragg wavelength. Calibration can distinguish between wavelength shifts caused by strain and temperature.

[0049] In a specific embodiment, the experimental device for monitoring the strain and temperature of anti-slip piles based on FBG further includes a monitoring system 4, which includes a motion camera with a resolution of 1920*1080, which can record information such as minute deformation and time during the experiment.

[0050] In one specific embodiment, the pile body withstands lateral pressure from the soil and transmits this pressure to a deeper, stable soil layer. Reinforcement is incorporated into the concrete anti-slip pile 6 to enhance the pile's bending and shear resistance. In the experiment, FBG strain and temperature sensing fibers 9 were used to monitor the strain and temperature of the anti-slip pile 6. To ensure a high survival rate of the optical fibers embedded in the rebar within the beam, the test beams were pre-treated by slotting the rebar along its length and then embedding the optical fibers within the slots. This method not only protects the optical fibers from damage but also facilitates a tight bond between the rebar and the optical fibers, enabling them to deform synergistically under load. Before attaching the optical fibers, the bottom of the grooves in the rebar should be carefully inspected to ensure there are no protrusions, ensuring a smooth and flat bottom. Dust and impurities should then be removed using a hair dryer, and the inner walls of the grooves should be wiped clean with 90% pure medical alcohol. After the alcohol evaporates, use 502 glue to secure the ends of the pre-stretched optical fiber. Then evenly apply AB glue to the grooves of the steel bars, ensuring that the test optical fiber is completely covered. Finally, remove any excess glue on the surface to ensure an even glue layer.

[0051] The following describes in detail the specific settings and functions of the precipitation simulation component and positioning component.

[0052] like Figure 5 and Figure 7 As shown, the rear side of the external box is fixedly connected to a simulated precipitation component, which includes a first gear 13. One side of the first gear 13 is movably connected to the external box through a bearing. A fastener 14 is fixedly connected to the surface of the first gear 13. A connecting frame 15 is sleeved on the surface of the fastener 14. The top of the connecting frame 15 is fixedly connected to a mounting frame 16. The bottom of the mounting frame 16 is movably connected to a spray pipe 17 through a bearing. The bottom of the spray pipe 17 is connected to a spray head 18. One side of the spray pipe 17 passes through one side of the connecting frame 15 and extends to the outside of the connecting frame 15. One side of the spray pipe 17 is connected to a joint 19. One side is movably connected to a second gear 20 through a bearing, and the second gear 20 is engaged with the first gear 13. A motor 21 is provided on the surface of the second gear 20, and the output end of the motor 21 is fixedly connected to the second gear 20. A water pressure gauge 22 is fixedly connected to the bottom of the inner cavity of the external box body, and counterweights 23 are fixedly connected on both sides of the bottom of the spray pipe 17. The counterweights 23 ensure that the nozzle 18 is always perpendicular to the spray pipe 17 when the angle changes. A reinforcement plate 24 is fixedly connected to one side of the motor 21, and one side of the reinforcement plate 24 is fixedly connected to the external box body. The bottom of one side of the external box body is connected to a drain pipe 37, and the drain pipes 37 are equidistantly arranged.

[0053] The entire simulated precipitation assembly achieves the following: through the transmission structure of the motor 21, the first gear 13, and the second gear 20, it can drive the sprinkler pipe 17 above the experimental device to simulate precipitation experiments, allowing for convenient adjustment of the precipitation position. The other end of the connector 19 is connected to an external water tank and a water pump via a hose. The water tank has sufficient capacity to meet the requirements of different precipitation durations and precipitation amounts during the experiment. The tank body is made of corrosion-resistant materials to prevent rust and corrosion during long-term use. The hose connects the water tank and the sprinkler pipe 17, delivering water to the simulated slope 1. The sprinkler heads 18 are evenly distributed above the simulated slope 1. Their types can be selected according to the simulated precipitation intensity and raindrop size, such as rotary sprinkler heads 18 and atomizing sprinkler heads 18. A flow control valve is installed on the water tank. By adjusting the valve opening, the water flow rate can be precisely controlled, thereby adjusting the precipitation intensity. This simulates precipitation processes of varying intensities and durations, and studies the effects of precipitation on the strain and temperature of the anti-sliding pile 6 and the stability of the simulated slope 1. By adjusting the intensity and duration of precipitation, the mechanical response of the anti-slip pile 6 under different conditions such as saturation and dry-wet cycles can be observed, providing data support for analyzing the reliability of the anti-slip pile 6 in dealing with precipitation factors in actual engineering projects, making the experimental results closer to real engineering scenarios.

[0054] like Figure 5 and Figure 6 As shown, the outer wall of the outer box includes a first movable plate 25, a second movable plate 26 is provided on one side of the first movable plate 25, and a connecting plate 27 is fixedly connected to the opposite side of the first movable plate 25 and the second movable plate 26. The top and bottom of the surface of the connecting plate 27 are provided with positioning components, and the positioning component includes a shell 28, which is provided on the surface of the connecting plate 27. The inner cavity of the shell 28 is threadedly connected to a threaded rod 29, one side of the threaded rod 29 passes through the outside of the shell 28 and is movably connected to a first limit plate 30 through a bearing, and a second limit plate 31 is fixedly connected to one side of the shell 28. The top and bottom of both sides of the connecting plate 27 are provided with a first limit plate. The plate 30 and the second limiting plate 31 are used in conjunction with the limiting groove 32, one side of the first limiting plate 30 and one side of the second limiting plate 31 both extend to the inner cavity of the limiting groove 32, one side of the hydraulic cylinder is movably connected to the connecting seat 33 through a rotating shaft, one side of the connecting seat 33 is fixedly connected to the fixing plate 34, and the side of the fixing plate 34 away from the connecting seat 33 is fixedly connected to the outer wall of the external box body by bolts, one side of the hydraulic cylinder is movably connected to the support plate 35 through a rotating shaft, the bottom of the support plate 35 is fixedly connected to the bottom plate 36, and the four corners of the top of the bottom plate 36 are provided with mounting holes, and the top of the bottom plate 36 is fixedly connected to the reinforcement seat, and one side of the reinforcement seat is fixedly connected to the support plate 35.

[0055] The effect achieved by the entire positioning assembly is that, by setting the positioning assembly, the first movable plate 25 and the second movable plate 26 can be connected so that they can form an integral structure, and at the same time, the effect of separation can also be achieved. By rotating the threaded rod 29, the threaded rod 29 drives the first limit plate 30 to move, and the first limit plate 30 is separated from the inner cavity of the limit groove 32, so that the outer shell 28 of the fixed connecting plate 27 can be removed, and the first movable plate 25 and the second movable plate 26 are independent of each other. The hydraulic cylinder is set to two groups, and under the action of the hydraulic cylinder, different forms of loads are stably applied to the simulated slope 1 and the anti-slip pile 6.

[0056] The working principle of the experimental device based on FBG to monitor the strain and temperature of anti-slip piles is as follows:

[0057] 1. The loading system 2 is used to apply horizontal or vertical loads to the anti-slip piles 6 in the simulated slope 1. The pressure sensor 10 is set on the anti-slip pile 6. The data processing system 5 can integrate the signals collected by the FBG strain and temperature sensing optical fiber 9, and demodulate the corresponding strain and temperature information through the FBG data demodulation instrument. The corresponding strain and temperature information is compared and verified with the strain and temperature information obtained by the pressure sensor 10, thereby evaluating the status of the anti-slip pile 6.

[0058] 2. The pressure sensor 10 is installed on the surface of the anti-slip pile 6 and buried in the designed model box together with the anti-slip pile 6. After the loading device applies the load, the pressure sensor 10 on the surface of the anti-slip pile 6 senses the change in soil pressure, causing the induction plate to deform. The induction plate is the direct force-bearing component of the soil pressure sensor. When the soil pressure changes, the induction plate will synchronously sense this change and deform. The deformation of the induction plate is transmitted to the vibrating wire, causing the tension of the vibrating wire to change. The vibration frequency of the vibrating wire is closely related to its tension. Therefore, changes in soil pressure will directly lead to changes in the vibration frequency of the vibrating wire. The excitation system excites the vibrating wire through devices such as electromagnetic coils to generate vibrations, and calculates the soil pressure by measuring the change in the vibration frequency of the vibrating wire. The change in the vibration frequency of the vibrating wire corresponds to the magnitude of the force. The vibration frequency signal of the vibrating wire is transmitted to a reading device or a data acquisition device. The vibrating wire soil pressure sensor can also synchronously measure the temperature value of the buried point, providing a more comprehensive basis for data analysis.

[0059] 3. The external water tank uses a water pump to allow water to flow through a hose to the sprinkler pipe 17 and nozzle 18. The flow regulating valve on one side of the water tank controls the water flow rate by changing the valve's flow cross-sectional area. According to the principles of fluid mechanics, the water flow rate is proportional to the flow rate, thereby achieving the adjustment of precipitation intensity. Different types of nozzles 18 disperse the water flow into raindrops of different sizes according to their own structural characteristics. For example, the rotary nozzle 18 uses centrifugal force to throw water out to form larger raindrops, while the atomizing nozzle 18 uses high pressure to atomize water into fine droplets, simulating different natural precipitation conditions. By setting different valve openings and nozzle 18 type combinations, simulations of various precipitation intensities and raindrop sizes can be achieved to meet different experimental requirements. By starting the motor 21, the motor 21 drives the second gear 20 to rotate, the second gear 20 drives the first gear 13 to rotate, the first gear 13 drives the second gear 20 to rotate, and the second gear 20 drives the connecting frame 15 to rotate, thereby driving the mounting frame 16 and the spray pipe 17 to perform fan-shaped movement, and performing spray precipitation treatment above the experimental device.

[0060] 4. By rotating the threaded rod 29, the threaded rod 29 drives the first limit plate 30 to move, and the first limit plate 30 is separated from the inner cavity of the limit groove 32, so that the outer shell 28 of the fixed connecting plate 27 can be removed, and the first movable plate 25 and the second movable plate 26 are independent of each other. The hydraulic cylinder is set into two groups, and under the action of the hydraulic cylinder, different forms of loads are stably applied to the simulated slope 1 and the anti-slip pile 6.

[0061] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the technical concepts disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0062] It should be understood that the present invention is not limited to the exact structure described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the scope of the appended claims.

Claims

1. An experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG, characterized by: It includes a simulated slope (1), a loading system (2), a strain and temperature monitoring system (3), a pressure sensor (10) and a data processing system (5); an anti-slip pile (6) is embedded in the simulated slope (1); the loading system (2) is used to apply a horizontal load or a vertical load to the anti-slip pile (6) in the simulated slope (1); the strain and temperature monitoring system (3) includes an FBG strain and temperature sensing optical fiber (9) distributed on the steel bars in the anti-slip pile (6); and the pressure sensor (10) is arranged on the anti-slip pile (6); the data processing system (5) can integrate the signals collected by the FBG strain and temperature sensing optical fiber (9), and demodulate the corresponding strain and temperature information through an FBG data demodulation instrument, and compare and verify it with the strain and temperature information obtained by the pressure sensor (10), so as to evaluate the state of the anti-slip pile (6); The simulated slope (1) includes an external box and a soil layer filled in the external box, the external box includes a rectangular box and two right-angled trapezoidal boxes that are connected to each other internally, the inclined surfaces of the two right-angled trapezoidal boxes constitute the slope of the simulated slope (1), the inner wall of the box is fixed, and the outer wall slides according to the step-by-step loading of the loading system (2) to reflect the influence of the health state of the anti-sliding pile (6) under different load force states; the outer wall is provided with a support point, and the load application process outside the box is realized by the extension and contraction of the hydraulic cylinder; Three anti-slide piles (6) of different sizes are distributed in the simulated slope (1), and each anti-slide pile (6) is provided with a pressure sensor (10) and an FBG strain and temperature sensing optical fiber (9); the pressure sensor (10) is a vibrating wire earth pressure sensor (10), and the anti-slide pile (6) is formed by a steel cage and concrete casting, and the steel cage includes four supporting steel bars (7) and steel rings (8), the four supporting steel bars (7) are arranged vertically and arranged in a rectangular shape, and a plurality of rectangular steel rings (8) distributed vertically are connected between the four supporting steel bars (7), and the steel rings (8) are connected to the four supporting steel bars (7). The four corners of the reinforcement ring (8) are connected to four supporting reinforcement bars (7) respectively. The positions where FBG strain and temperature sensing optical fibers (9) need to be arranged are located on the reinforcement bars constituting the supporting reinforcement bars (7) or the reinforcement ring (8). A groove is provided downwardly on the surface of the reinforcement bars along the length direction of the reinforcement bars. The FBG strain and temperature sensing optical fibers (9) are arranged in the groove. The FBG strain and temperature sensing optical fibers (9) are pasted in the groove. The loading system (2) is a hydraulic cylinder. The outer wall of the box slides due to the load force provided by the hydraulic cylinder to simulate the stress state of the anti-slip pile (6) under the set predetermined conditions. One side of the hydraulic cylinder is connected to the fixed seat through the connecting seat (33), and one side of the fixed seat is fixedly connected to the outer wall of the external box body, which can support the external box body; one side of the hydraulic cylinder is movably connected to the support plate (35) through the rotating shaft, and the bottom of the support plate (35) is fixedly connected to the bottom plate (36), and the four corners of the top of the bottom plate (36) are provided with mounting holes. The top of the bottom plate (36) is fixedly connected to the reinforcement seat, and one side of the reinforcement seat is fixedly connected to the support plate (35).

2. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 1, characterized in that: It also includes a monitoring system (4), which is a motion camera used to record the slight deformation and deformation time during the experiment.

3. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 1, characterized in that: The rear side of the external box is fixedly connected to a simulated precipitation component, and the simulated precipitation component includes a first gear (13), one side of the first gear (13) is movably connected to the external box via a bearing, a fastener (14) is fixedly connected to the surface of the first gear (13), a connecting frame (15) is sleeved on the surface of the fastener (14), the top of the connecting frame (15) is fixedly connected to a mounting frame (16), the bottom of the mounting frame (16) is movably connected to a spray pipe (17) via a bearing, and the bottom of the spray pipe (17) is connected to a spray head ( 18), one side of the spray pipe (17) passes through one side of the connecting frame (15) and extends to the outside of the connecting frame (15), one side of the spray pipe (17) is connected to a joint (19), one side of the rear end of the external box body is movably connected to a second gear (20) through a bearing, the second gear (20) is meshed with the first gear (13), a motor (21) is provided on the surface of the second gear (20), the output end of the motor (21) is fixedly connected to the second gear (20), and a water pressure gauge (22) is fixedly connected to the bottom of the inner cavity of the external box body.

4. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 3, characterized in that: Counterweights (23) are fixedly connected to both sides of the bottom of the spray pipe (17), and the counterweights (23) ensure that the spray head (18) is always in a vertical state with the spray pipe (17) when the angle changes.

5. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 3, characterized in that: A reinforcement plate (24) is fixedly connected to one side of the motor (21), and one side of the reinforcement plate (24) is fixedly connected to the external box.

6. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 5, characterized in that: The outer wall of the external box body includes a first movable plate (25), a second movable plate (26) is provided on one side of the first movable plate (25), and a connecting plate (27) is fixedly connected to the opposite side of the first movable plate (25) and the second movable plate (26), and positioning components are provided on the top and bottom of the surface of the connecting plate (27).

7. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 6, characterized in that: The positioning assembly comprises a shell (28), the shell (28) being arranged on the surface of the connecting plate (27), and the inner cavity of the shell (28) being threadedly connected to a threaded rod (29).

8. The experimental device for monitoring the strain and temperature of anti-sliding piles based on FBG according to claim 7, characterized in that: One side of the threaded rod (29) passes through the outside of the housing (28) and is movably connected to a first limit plate (30) through a bearing. One side of the housing (28) is fixedly connected to a second limit plate (31). The top and bottom of both sides of the connecting plate (27) are provided with limit grooves (32) for use with the first limit plate (30) and the second limit plate (31). One side of the first limit plate (30) and one side of the second limit plate (31) extend to the inner cavity of the limit groove (32).

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