In-situ monitoring sensor for hardening time of prestressed tendon slow-bonding agent and use method of in-situ monitoring sensor

Abstract

The invention provides a pre-stressed tendon slow adhesive hardening time in-situ monitoring sensor and a use method thereof. The pre-stressed tendon slow adhesive hardening time in-situ monitoring sensor comprises a protective outer cylinder, an optical fiber pasting plate, a first grating and a second grating, the internal space of the protective outer cylinder is divided into a slow binder contact cavity and a slow binder isolation cavity; the optical fiber pasting plate is located in the protective outer cylinder, a first grating is fixed to the portion, located in the slow binder contact cavity, of the optical fiber pasting plate, and a second grating is fixed to the portion, located in the slow binder isolation cavity, of the optical fiber pasting plate. And after the second grating is connected with the first grating through an optical fiber, an optical fiber pigtail is led out for connecting a laser demodulator. According to the device and the method, the effects of influence factors such as temperature and stress of the surrounding environment of the retarder can be fully considered, and accurate data of on-site hardening of the retarder are provided through in-situ monitoring, so that the construction accuracy and the structural safety are ensured.

Description

Technical Field

[0001] This invention belongs to the field of materials testing technology, specifically relating to an in-situ monitoring sensor for the hardening time of prestressed tendon adhesive and its usage method. Background Technology

[0002] Traditional delayed-bonding prestressed tendons are widely used in prestressed structures. Delayed-bonding agents play a crucial role in delayed-bonding prestressed tendons, ensuring ease of construction while improving the structure's mechanical properties and durability. The curing time of the delayed-bonding agent is adjusted primarily based on project requirements to meet different construction cycle needs. Real-time monitoring of the curing process and precise measurement of the curing time provide reliable data for construction quality assessment, ensuring project quality. When the curing time of the delayed-bonding agent does not match the construction cycle, it will affect the quality of the structural engineering.

[0003] However, existing technologies cannot meet the need for in-situ monitoring of the hardening time of prestressing tendon retarders within the engineering structure at the project site. The lack of effective methods for in-situ monitoring of retarder hardening time makes it difficult to accurately grasp the bonding state of the prestressing tendons during construction, thus posing potential risks to project quality. In practice, the hardening time of retarders is usually determined according to the product manufacturer's instructions. However, the hardening environment of the retarder in the structure differs significantly from the test conditions before the product leaves the factory. For example, the in-situ retarder encasing the prestressing tendons inside the component is affected by the high temperature generated by the hydration reaction of the concrete, the diurnal temperature variation of the surrounding environment, and the stress generated by the tensioning of the prestressing tendons inside the component. The aforementioned actual outdoor environmental conditions are not reflected in the pre-shipment tests, which may lead to a significant deviation between the actual hardening time and the standard in the manufacturer's instructions, affecting construction progress and quality.

[0004] Utility model patent application number 201420228289.8 proposes a device for real-time monitoring of the sol-gel solidification process. This patent provides a laboratory measurement method using fiber Bragg gratings to measure sol-gel solidification. The fiber Bragg grating probe is completely immersed in the solution to be tested. Utilizing the stress sensitivity of the fiber Bragg grating probe, the shift of the center wavelength of the reflectance spectrum of the probe is observed using a spectrometer, thereby allowing real-time monitoring of the sol-gel solidification process. The change in the center wavelength shift of the reflectance spectrum of the fiber Bragg grating probe is influenced not only by stress changes caused by sol hardening but also by direct changes in ambient temperature. However, this method does not consider the influence of temperature. Therefore, this method is generally applicable to laboratory settings, where the measurement effect is better when the indoor ambient temperature is kept constant. However, when the influence of ambient temperature needs to be considered, the measurement error is relatively large.

[0005] In view of this, the present invention proposes an in-situ monitoring sensor for the hardening time of prestressed tendon adhesive. Summary of the Invention

[0006] The purpose of this invention is to propose an in-situ monitoring sensor for the curing time of prestressed tendon adhesive and its usage method. By installing the sensor inside the on-site component, effective in-situ monitoring of the curing time of the adhesive under the on-site component environment can be achieved, providing reliable data for the safe production and quality assurance of the component.

[0007] To achieve the above objectives, the technical solution of the present invention is: an in-situ monitoring sensor for the curing time of prestressed tendon adhesive, comprising a protective outer cylinder 3, an optical fiber bonding plate 6, a first grating 7, and a second grating 8; the internal space of the protective outer cylinder 3 is divided into an adhesive contact cavity and an adhesive isolation cavity; the optical fiber bonding plate 6 is located inside the protective outer cylinder 3, and the portion of the optical fiber bonding plate 6 located in the adhesive contact cavity is fixed with the first grating 7, and the portion of the optical fiber bonding plate 6 located in the adhesive isolation cavity is fixed with the second grating 8; the second grating 8 is connected to the first grating 7 via an optical fiber, and an optical fiber pigtail 1 is led out to connect to a laser demodulator. The laser demodulator injects laser light into the sensor and captures the laser wavelength data returned by the first grating 7 and the second grating 8. The curing time of the adhesive is determined based on the correlation analysis results of the two sets of laser wavelength data.

[0008] Preferably, the portion of the optical fiber bonding plate 6 located in the contact cavity of the slow adhesive has a serrated structure at its left and right edges to enhance the bonding strength between the portion of the optical fiber bonding plate 6 located in the contact cavity of the slow adhesive and the slow adhesive.

[0009] Preferably, the fiber optic bonding plate 6 is fixed inside the protective outer cylinder 3 by a fixing bracket 2.

[0010] Preferably, the protective outer cylinder 3 is a cylindrical shape with openings at both ends.

[0011] Preferably, the adhesive release chamber is formed by two semi-circular closed partitions 5 respectively disposed in the middle and at the ends of the protective outer cylinder 3, a rectangular closed partition 4 connecting the straight sides of the two semi-circular closed partitions 5, and the inner wall of the protective outer cylinder 3 connecting the curved sides of the two semi-circular closed partitions 5; the area in the internal space of the protective outer cylinder 3 other than the adhesive release chamber is the adhesive release contact chamber, which is filled with adhesive release.

[0012] Preferably, the optical fiber bonding plate 6 passes through the soft adhesive contact cavity, through the semi-circular closed partition 5 located in the middle of the protective outer cylinder 3, and extends into the soft adhesive isolation cavity; one end of the portion of the optical fiber bonding plate 6 located in the soft adhesive isolation cavity is fixedly connected to the semi-circular closed partition 5 located in the middle of the protective outer cylinder 3, and the other end is suspended; the portion of the optical fiber bonding plate 6 located in the soft adhesive isolation cavity has no contact with the rectangular closed partition 4 or the partial inner wall of the protective outer cylinder 3.

[0013] Preferably, the fixing bracket 2 is provided in three sets, which are respectively set at the end of the fiber optic bonding plate 6 near the first grating 7 and at the two semi-circular closed partitions 5.

[0014] Preferably, the fixing bracket 2 located at the end of the fiber optic bonding plate 6 near the first grating 7 adopts a cross structure; the middle part of the cross-shaped fixing bracket 2 is fixedly connected to the fiber optic bonding plate 6, and the end of the cross-shaped fixing bracket 2 is not connected to the protective outer cylinder 3, and the fiber optic bonding plate 6 is supported only by the cross-shaped fixing bracket 2; the fixing brackets 2 located at the two semi-circular closed partitions 5 adopt a straight structure to connect the semi-circular closed partitions 5 and the inner wall of the protective outer cylinder 3.

[0015] A method for using an in-situ monitoring sensor for the curing time of prestressed tendon adhesive delay agent includes the following steps: S1. After filling the contact cavity of the sensor with the adhesive, fix it to the position of the adhesive reinforcement and connect the sensor to the laser demodulator through the fiber optic pigtail 1. S2. After setting the data acquisition unit duration of the laser demodulator, the laser demodulator is used to shoot laser along the optical fiber into the sensor and capture the laser wavelength sequence returned by the first grating 7 and the second grating 8. S2. Calculate the correlation coefficient between the two sets of laser wavelength sequences within a predefined time period. When the calculated correlation coefficient approaches 1, it indicates that the hardening process of the adhesive is nearing completion.

[0016] Preferably, the correlation coefficient r The calculation is as follows: in, X i and Y i These are the laser wavelength observations returned by the first grating (7) and the second grating (8), respectively. and These are the average values ​​of two sets of laser wavelength sequences within a predefined time period.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a sensor design structure that can be installed inside the prestressing tendons on site, forming an integral whole with them. This enables in-situ measurement of the hardening of the prestressing tendon retarder within the component, allowing real-time monitoring of the hardening process. This solution not only provides an effective method for monitoring the hardening time of the retarder but also fully considers the influence of environmental factors such as temperature and stress on the retarder. Providing accurate data on the hardening of the retarder through in-situ monitoring ensures construction precision and structural safety. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the sensor's appearance at one angle. Figure 2 This is a schematic diagram of the sensor from another angle. Figure 3 This is a schematic diagram of the internal structure of the sensor at an angle. Figure 4 This is a schematic diagram of the internal structure of the sensor from another angle.

[0019] In the picture: 1-Fiber optic pigtail; 2-Fixed bracket; 3-Protective outer cylinder; 4-Rectangular enclosed partition; 5-Semi-circular enclosed partition; 6-Fiber optic bonding plate; 7-First grating; 8-Second grating. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-4 The technical solution of the present invention will be described in detail below.

[0021] This invention proposes an in-situ monitoring sensor for the curing time of prestressed tendon adhesive, comprising a protective outer cylinder 3, an optical fiber bonding plate 6, a first grating 7, and a second grating 8. The internal space of the protective outer cylinder 3 is divided into an adhesive contact cavity and an adhesive isolation cavity. The optical fiber bonding plate 6 is located inside the protective outer cylinder 3, and the portion of the optical fiber bonding plate 6 located in the adhesive contact cavity is fixed with the first grating 7, while the portion of the optical fiber bonding plate 6 located in the adhesive isolation cavity is fixed with the second grating 8. The second grating 8 is connected to the first grating 7 via an optical fiber, and an optical fiber pigtail 1 is led out for connection to a laser demodulator.

[0022] In this embodiment, the portion of the fiber optic bonding plate 6 located in the contact cavity of the adhesive buffer has a serrated structure at its left and right edges. This is to enhance the bonding strength between the fiber optic bonding plate 6 in the contact cavity and the adhesive buffer, fully reflecting the gradual change in the constraint effect of the adhesive buffer on the fiber optic bonding plate 6 during the curing process. Simultaneously, it ensures that the adhesive buffer maintains consistent linear expansion deformation with the first grating 7 after curing. The sensitivity of the first grating 7 to strain and temperature changes accurately captures subtle differences in the gradual curing process of the adhesive buffer, thereby monitoring the curing time of the adhesive buffer. The portion of the fiber optic bonding plate 6 with the second grating 8 fixed in the adhesive buffer isolation cavity does not need to contact the adhesive buffer and does not reflect the curing of the adhesive buffer; therefore, it is not serrated.

[0023] In this embodiment, the fiber optic bonding plate 6 is fixed inside the protective outer cylinder 3 by a fixing bracket 2.

[0024] In this embodiment, the protective outer cylinder 3 is a cylindrical shape with openings at both ends.

[0025] In this embodiment, the adhesive buffer cavity is formed by two semi-circular closed partitions 5 respectively disposed in the middle and end of the protective outer cylinder 3, a rectangular closed partition 4 connecting the straight sides of the two semi-circular closed partitions 5, and the inner wall of the protective outer cylinder 3 connecting the curved sides of the two semi-circular closed partitions 5. The area inside the protective outer cylinder 3, excluding the adhesive buffer cavity, is the adhesive buffer contact cavity, which is filled with adhesive buffer. Benefiting from the protection of the semi-cylindrical adhesive buffer cavity, the portion of the fiber optic bonding plate 6 that fixes the second grating 8 located inside the adhesive buffer cavity is completely isolated from the adhesive buffer, thereby avoiding the indirect influence of the adhesive buffer on the portion of the fiber optic bonding plate 6 located inside the adhesive buffer cavity.

[0026] In this embodiment, the fiber optic bonding plate 6 extends from the adhesive buffer contact cavity through the semi-circular closed partition 5 located in the middle of the protective outer cylinder 3 and into the adhesive buffer isolation cavity. One end of the fiber optic bonding plate 6 located in the adhesive buffer isolation cavity is fixedly connected to the semi-circular closed partition 5 located in the middle of the protective outer cylinder 3, while the other end is suspended. The portion of the fiber optic bonding plate 6 located in the adhesive buffer isolation cavity has no contact with the rectangular closed partition 4 or the partial inner wall of the protective outer cylinder 3. To further avoid the indirect influence of the adhesive buffer on the portion of the fiber optic bonding plate 6 located in the adhesive buffer isolation cavity, the fiber optic bonding plate 6 and the rectangular closed partition 4 are physically separated in the structural design, maintaining a certain distance between the two plates to avoid the potential influence of the strain changes of the rectangular closed partition 4 on the bonding plate. Through the above structural design, it can be fully ensured that the deformation of the second grating 8 is completely unaffected by the hardening of the adhesive buffer.

[0027] In this embodiment, the fixing bracket 2 is provided in three sets, respectively located at the end of the fiber optic bonding plate 6 near the first grating 7 and at the two semi-circular closed partitions 5. The fixing bracket 2 located at the end of the fiber optic bonding plate 6 near the first grating 7 adopts a cross structure. The middle part of the cross-shaped fixing bracket 2 is fixedly connected to the fiber optic bonding plate 6, and the end of the cross-shaped fixing bracket 2 is not connected to the protective outer cylinder 3. The fiber optic bonding plate 6 is supported only by the cross-shaped fixing bracket 2, avoiding the binding of the cross-shaped fixing bracket 2 on the deformation of the fiber optic bonding plate 6. The fixing brackets 2 located at the two semi-circular closed partitions 5 adopt a straight structure to connect the semi-circular closed partition 5 and the inner wall of the protective outer cylinder 3. The above arrangement ensures the correct position of the core sensing components of the sensor (first grating 7 and second grating 8) and the safety of the sensor operation.

[0028] This invention also proposes a method for using an in-situ monitoring sensor for the curing time of prestressed tendon adhesive, specifically including the following steps: S1. After filling the contact cavity of the sensor with the adhesive, fix it to the position of the adhesive reinforcement and connect the sensor to the laser demodulator through the fiber optic pigtail 1. S2. After setting the data acquisition unit duration of the laser demodulator, the laser demodulator is used to shoot laser along the optical fiber into the sensor and capture the laser wavelength sequence returned by the first grating 7 and the second grating 8. S2. Calculate the correlation coefficient between the two sets of laser wavelength sequences within a predefined time period. When the calculated correlation coefficient approaches 1, it indicates that the hardening process of the adhesive is nearing completion. After hardening, the adhesive possesses a certain strength, enabling it to constrain the bonding plate, and this constraint will no longer change. That is, the adhesive, the fiber bonding plate 6, and the first grating 7 will deform collaboratively and maintain consistency. This will result in a correlation coefficient r=1 between the two acquired laser wavelength values, which is the principle used to determine the hardening of the adhesive.

[0029] This sensor structure can also be uniformly encapsulated with the prestressing tendons during the production stage through a specific fixing method, thereby forming an intelligent, slow-bonding prestressing tendon. This eliminates the need for on-site filling of slow-bonding agent and fixing installation.

[0030] In this embodiment, the correlation coefficient r The calculation is as follows: in, X i and Y i These are the laser wavelength observations returned by the first grating (7) and the second grating (8), respectively. and These are the average values ​​of two sets of laser wavelength sequences within a predefined time period. The following is a detailed explanation of the sensor testing preparation and testing principles: Sensor test preparation: The adhesive is slowly injected into the circular opening of the protective outer cylinder 3 on one side of the fiber optic pigtail 1 of the sensor, allowing it to slowly overflow from the semi-circular opening on the other side. This ensures that the internal space of the protective outer cylinder 3 is filled with adhesive, and that the adhesive completely covers the serrated portion of the fiber optic bonding plate 6. The semi-cylindrical sealed space inside the protective cylinder is not filled with adhesive to ensure that the portion of the fiber optic bonding plate 6 containing the second grating 8, located within the adhesive isolation cavity, can deform freely without being affected by the hardening of the adhesive. By comparing the wavelength changes of the first grating 7 and the second grating 8 with varying ambient temperature, correlation analysis is performed to assess the hardening state of the adhesive.

[0031] In engineering practice, sensors filled with the same type of retardant can be fixedly installed inside the prestressed tendon structure to ensure that the environment of the retardant inside the sensor is exactly the same as that of the prestressed tendon in the structure. This allows the influence of temperature changes caused by the heat of hydration of concrete on the retardant to be considered during monitoring, making the measurement results more consistent with engineering practice.

[0032] Because the sensor structure is actually placed inside the prestressed tendon structure, the sensor components (first grating 7 and second grating 8) are simultaneously exposed to the same external environment, and changes in ambient temperature affect both gratings. The sensor primarily collects the changes in the center wavelength of the two gratings caused by changes in ambient temperature. However, the first grating 7 is also affected by the curing process of the adhesive retarder; that is, the first grating 7 is affected by both ambient temperature and the curing process of the adhesive retarder, while the second grating 8 is only affected by changes in ambient temperature. Through analysis and processing of the collected data, the influence of temperature changes can be eliminated, while the influence of the wavelength changes caused by the curing process of the adhesive retarder can be fully reflected. This scheme overcomes the shortcomings of similar schemes for detecting sol-gel curing processes, which only consider the influence of the curing process and do not consider the influence of ambient temperature.

[0033] Sensor testing principle: By mathematically analyzing the correlation between the wavelength changes of the first grating 7 and the second grating 8, the change in the effect of the slow adhesive on the first grating 7 during the gradual hardening process is obtained. This effect no longer changes after the slow adhesive is completely hardened, thus determining that the slow adhesive is completely hardened.

[0034] The sensor's fiber optic pigtail connects to the laser demodulator. The demodulator directs laser light along the fiber optic cable towards the sensor. The laser light travels along the fiber to the first grating 7 and returns at a specific wavelength. The remaining laser light continues forward to the second grating 8 and returns at a specific wavelength. These two returning laser beams of different wavelengths travel along the fiber optic cable back to the demodulator, where they are captured and analyzed. The analyzed laser wavelength is the sensor's acquisition signal, used to analyze the hardening process of the adhesive. The detailed test principle is as follows: The first grating 7 and the second grating 8 are installed in the same way, and the material of the fixed fiber optic bonding plate 6 is the same. When the ambient temperature changes at the same rate, the wavelength changes of the two gratings are the same, that is, the correlation coefficient of the wavelength values ​​of the two gratings should be 1. They are perfectly positively correlated, that is, they increase or decrease synchronously, and the increase or decrease in wavelength value is equal.

[0035] Because the fiber optic bonding plate 6, to which the first grating 7 is attached, is constrained by the slow adhesive during deformation, the wavelength changes of the first grating 7 and the second grating 8 differ, resulting in the correlation coefficient between their wavelength values ​​no longer being 1. The correlation between them changes in two ways: the change in wavelength direction is no longer synchronized, and the numerical values ​​of the wavelength changes are no longer the same. This situation will persist throughout the hardening process of the slow adhesive. As the slow adhesive hardens, its constraint on the bonding plate continuously strengthens, causing the change in laser wavelength of the first grating 7 to remain constant under varying ambient temperature conditions. Consequently, the correlation coefficient between the wavelengths of the first grating 7 and the second grating 8 remains variable. This state will continue until the slow adhesive is completely hardened. Once hardened, the constraint of the slow adhesive on the bonding plate will no longer change, and the change in laser wavelength of the first grating 7 under varying ambient temperature conditions will return to a consistent value. After the adhesive hardens, although the laser wavelength changes of the first grating 7 and the second grating 8 under the unit temperature change are different, their changes will synchronize again, that is, the correlation coefficient of their laser wavelength values ​​will approach 1 again, showing a strong and perfect positive correlation.

[0036] Two sets of laser wavelength values ​​were collected from the first grating 7 and the second grating 8, and the correlation coefficient between the two sets of values ​​was calculated. By analyzing the correlation coefficient, when the value approaches 1, the hardening status of the adhesive can be determined.

[0037] In summary, delayed-bonding prestressing tendons are widely used in prestressed structures, optimizing construction processes and increasing on-site work efficiency. The curing time of the delayed adhesive is a crucial factor affecting project schedule, safety, and quality. In engineering practice, the curing time parameters of the delayed adhesive are determined by manufacturers through specific formulations and tests, and are specified in the product manuals for the prestressing tendons. However, the curing test measurements of the delayed adhesive in the manufacturer's laboratory differ significantly from the environment of the on-site components, potentially rendering the curing time specified in the original manual inapplicable to the on-site environment. Therefore, this invention proposes a feasible monitoring sensor structure scheme. By installing sensors inside the on-site components, effective in-situ monitoring of the curing time of the delayed adhesive under the on-site environment can be achieved, providing reliable data for the safe production and quality assurance of the components.

[0038] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. An in-situ monitoring sensor for the curing time of prestressed tendon adhesive, characterized in that, The device includes a protective outer cylinder (3), an optical fiber bonding plate (6), a first grating (7), and a second grating (8). The internal space of the protective outer cylinder (3) is divided into a slow adhesive contact cavity and a slow adhesive isolation cavity. The optical fiber bonding plate (6) is located inside the protective outer cylinder (3), and the portion of the optical fiber bonding plate (6) located in the slow adhesive contact cavity is fixed with the first grating (7), while the portion of the optical fiber bonding plate (6) located in the slow adhesive isolation cavity is fixed with the second grating (8). The second grating (8) is connected to the first grating (7) via an optical fiber and then leads out an optical fiber pigtail (1) for connecting to a laser demodulator. The laser demodulator injects laser light into the sensor and captures the laser wavelength data returned by the first grating (7) and the second grating (8). The hardening time of the slow adhesive is determined based on the correlation analysis results of the two sets of laser wavelength data.

2. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 1, characterized in that, The fiber optic bonding plate (6) has a serrated structure at the left and right edges of the portion located in the contact cavity of the slow adhesive to enhance the bonding strength between the portion of the fiber optic bonding plate (6) located in the contact cavity of the slow adhesive and the slow adhesive.

3. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 1, characterized in that, The fiber optic bonding plate (6) is fixed inside the protective outer cylinder (3) by a fixing bracket (2).

4. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 3, characterized in that, The protective outer cylinder (3) is a cylindrical shape with openings at both ends.

5. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 4, characterized in that, The adhesive release chamber is formed by two semi-circular closed partitions (5) respectively located in the middle and at the ends of the protective outer cylinder (3), a rectangular closed partition (4) connecting the straight sides of the two semi-circular closed partitions (5), and the inner wall of the protective outer cylinder (3) connecting the curved sides of the two semi-circular closed partitions (5); the area in the internal space of the protective outer cylinder (3) other than the adhesive release chamber is the adhesive contact chamber, which is filled with adhesive.

6. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 5, characterized in that, The fiber optic bonding plate (6) passes through the contact cavity of the adhesive buffer, through the semi-circular closed partition (5) located in the middle of the protective outer cylinder (3), and extends into the adhesive buffer isolation cavity. One end of the fiber optic bonding plate (6) located in the adhesive buffer isolation cavity is fixedly connected to the semi-circular closed partition (5) located in the middle of the protective outer cylinder (3), and the other end is suspended. The part of the fiber optic bonding plate (6) located in the adhesive buffer isolation cavity has no contact with the rectangular closed partition (4) and the partial inner wall of the protective outer cylinder (3).

7. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 6, characterized in that, The fixed bracket (2) is provided in three sets, which are respectively set at the end of the fiber bonding plate (6) near the first grating (7) and at the two semi-circular closed partitions (5).

8. The in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 7, characterized in that, The fixing bracket (2) located at the end of the fiber bonding plate (6) near the first grating (7) adopts a cross structure; the middle part of the fixing bracket (2) of the cross structure is fixedly connected to the fiber bonding plate (6), and the end of the fixing bracket (2) of the cross structure is not fixedly connected to the protective outer cylinder (3). The fiber bonding plate (6) is supported only by the fixing bracket (2) of the cross structure; the fixing brackets (2) located at the two semi-circular closed partitions (5) adopt a straight structure to connect the semi-circular closed partitions (5) and the inner wall of the protective outer cylinder (3).

9. A method for using a prestressed tendon adhesive hardening time in-situ monitoring sensor according to any one of claims 1-8, characterized in that, Specifically, the following steps are included: S1. After filling the contact cavity of the sensor with the slow adhesive, fix it at the position of the slow adhesive rib, and connect the sensor to the laser demodulator through the fiber optic pigtail (1). S2. After setting the data acquisition unit duration of the laser demodulator, the laser demodulator is used to shoot laser along the optical fiber into the sensor and capture the laser wavelength sequence returned by the first grating (7) and the second grating (8). S2. Calculate the correlation coefficient between the two sets of laser wavelength sequences within a predefined time period. When the calculated correlation coefficient approaches 1, it indicates that the hardening process of the adhesive is nearing completion.

10. The method of using the in-situ monitoring sensor for the hardening time of prestressed tendon adhesive according to claim 9, characterized in that, Correlation coefficient r The calculation is as follows: in, X i and Y i These are the laser wavelength observations returned by the first grating (7) and the second grating (8), respectively. and These are the average values ​​of two sets of laser wavelength sequences within a predefined time period.

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