A Dam Structure Monitoring System and Installation Method Based on Intelligent Temperature Strain Sensing

Abstract

This invention belongs to the field of dam safety monitoring, specifically relating to a dam structure monitoring system based on intelligent temperature and strain sensing. It includes a sensing unit installed within the dam foundation, connected to a monitoring instrument. A monitoring hole is provided within the dam foundation. The sensing unit includes a fiber optic strain sensor and a fiber optic temperature sensor. The temperature sensor is located at the bottom of the monitoring hole, and the strain sensor is located on the circumferential sidewall of the monitoring hole. This invention achieves coordinated acquisition of temperature and strain parameters, overcoming the shortcomings of insufficient sensing dimensions of a single sensor. The invention also discloses an installation method for the dam structure monitoring system. Through a double-sealing design—using a polyurethane foam filling layer to bury the sensing unit and a sealing cap combined with weather-resistant adhesive to seal the monitoring hole opening—a reliable waterproof and moisture-proof structure is formed, further ensuring the stability of the sensing unit's operating environment.

Description

Technical Field

[0001] This invention belongs to the field of dam safety monitoring, specifically relating to a dam structure monitoring system and installation method based on intelligent temperature strain sensing. Background Technology

[0002] As a core infrastructure for water resource regulation and flood control, the safe and stable operation of dams throughout their entire life cycle is directly related to the livelihood of people in the basin and the overall economic development of the region. Traditional daily dam inspections mainly rely on discretely deployed electronic or mechanical sensors such as strain gauges, thermometers, and piezometers. Data is acquired manually or through simple automation, resulting in long inspection cycles, data lag, and a lifespan far shorter than that of the main dam structure. Furthermore, replacing and maintaining embedded sensors may require destructive construction work on the dam, which is costly and difficult to implement in some cases. In recent years, a construction method of reserving monitoring holes at monitoring points has also emerged. Electronic sensors can be installed in these holes later for easy maintenance and subsequent upgrades of monitoring equipment. However, this method requires a much better seal than the embedded method; otherwise, the electronic sensors will be exposed to the high humidity environment of the dam, making them susceptible to moisture damage. Regularly maintaining the sealing of the monitoring holes further increases the workload of inspections. Therefore, there is an urgent need for a dam structure monitoring system and installation method based on intelligent temperature and strain sensing to reduce maintenance costs and improve inspection efficiency. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a dam structure monitoring system and installation method based on intelligent temperature strain sensing, which can effectively reduce the maintenance cost of dam inspection and improve inspection efficiency.

[0004] The specific technical solution adopted in this invention is as follows:

[0005] A dam structure monitoring system based on intelligent temperature and strain sensing includes a sensing unit installed in the dam foundation, the sensing unit being connected to a monitoring instrument, a monitoring hole being installed in the dam foundation, and the sensing unit including a fiber optic strain sensor and a fiber optic temperature sensor, the temperature sensor being installed at the bottom of the monitoring hole, and the strain sensor being installed on the circumferential sidewall of the monitoring hole.

[0006] The strain sensor is mounted on the circumferential side wall of the monitoring hole using a mounting bracket. The mounting bracket includes a fixing ring and a transmission mechanism disposed within the fixing ring. The transmission mechanism includes a transmission rod, the fixed section of which is fixedly connected to the inner side wall of the fixing ring, and the other end of which is a suspended section. Two sets of transmission rods are arranged symmetrically around the center of the fixing ring. The strain sensor is a rod-shaped structure that is tied and fixed between the suspended sections of the two sets of transmission rods.

[0007] The fixed section and the suspended section of the transmission rod are integrally arranged in an L-shape. The transmission mechanism also includes an adjusting screw, which is connected between the suspended sections of the two sets of transmission rods. The connection point of the adjusting screw is hinged to the suspended section. The distance from the connection point to the connection point between the suspended section and the fixed section is less than the distance from the connection point to the end of the suspended section.

[0008] A notch-shaped thinning groove is provided at the junction where the fixed section and the suspended section connect.

[0009] The suspended section is provided with a hinge seat at its end. The hinge seat has an L-shaped sheet structure. One end of the hinge seat is hinged to the end of the suspended section, and the other end of the hinge seat is provided with a connection hole and a wire passage groove.

[0010] Multiple connection holes are provided and arranged around the wire passage groove. The wire passage groove is connected to the edge of the side of the hinge seat, forming an open groove structure.

[0011] An installation method for a dam structure monitoring system based on intelligent temperature strain sensing includes the following steps.

[0012] S1. Install a sensing unit inside the monitoring hole at the location to be monitored;

[0013] S2. After installation, fill the monitoring holes with polyurethane foam, and use the filling layer formed by the polyurethane foam to bury the sensing unit;

[0014] S3. Use weather-resistant adhesive to attach a sealing cap to the opening of the monitoring hole, lead the connecting optical fiber of the sensing unit out from the through hole reserved in the sealing cap, and seal the through hole with weather-resistant adhesive;

[0015] S4. Connect the optical fiber to the monitoring instrument to monitor the dam structure.

[0016] In step S1, the monitoring hole is set as a circular hole, the fixing ring is coaxially arranged inside the monitoring hole, the outer wall of the fixing ring abuts and limits the inner wall of the monitoring hole, and the gap between the fixing ring and the inner wall of the monitoring hole is filled with adhesive.

[0017] After the fixing ring is placed, the adjustment model with the same external dimensions as the strain sensor is installed between the two sets of hinge seats. The length of the adjusting screw is adjusted so that the distance between the hinge seats on the two sets of transmission rods abuts against the flanges reserved at both ends of the strain sensor. Then the adjustment model is removed and the strain sensor is installed on the hinge seats with the adjusted spacing.

[0018] In step S2, if the old monitoring sensor is removed from the monitoring hole, the hole wall needs to be cleaned and the hole wall except the bottom needs to be re-coated with waterproof material to improve the waterproof performance of the hole wall. The polyurethane foam filling layer and the sealing cover leave a gap to form a closed air cavity. The sealing cover has a pre-set air injection hole that communicates with the air cavity. According to the preset maintenance cycle, the air cavity is inflated to the set pressure through the air injection hole. If the pressure holding time is less than the set value, the sealing cover needs to be opened to inspect and repair the sealing cover and the internal filling layer to prevent water from entering.

[0019] In step S1, the strain sensors of the sensing unit are arranged in two sets at intervals with the help of the mounting bracket. The sensing directions of the two sets of strain sensors are arranged perpendicularly. The temperature sensor is attached and fixed on the plane at the bottom of the monitoring hole with adhesive.

[0020] The beneficial effects of this invention are:

[0021] This invention employs a fiber optic strain sensor and a temperature sensor to construct the sensing unit. Leveraging the fiber optic strain sensor's ability to withstand high humidity and strong electromagnetic interference, it stably provides sensing parameters in the harsh service environment of a dam. Two sets of strain sensors are installed vertically using a mounting bracket, enabling the capture of strain information in multiple dimensions of the dam's sidewall. Combined with a temperature sensor attached to the bottom of the monitoring hole, it achieves coordinated acquisition of temperature and strain parameters, overcoming the shortcomings of insufficient sensing dimensions of a single sensor and significantly improving the accuracy and data integrity of dam structural condition monitoring.

[0022] This invention employs a double-sealing design, where a polyurethane foam filling layer buries the sensing unit, and a sealing cap, combined with weather-resistant adhesive, seals the monitoring hole opening. This creates a reliable waterproof and moisture-proof structure, preventing moisture intrusion that could corrode the mounting bracket and fiber optic grating sensor housing. Simultaneously, the air cavity and injection hole reserved between the filling layer and the sealing cap within the monitoring hole allow for periodic pressure testing to check the seal, enabling early detection and timely repair of potential leaks, further ensuring the stability of the sensing unit's operating environment. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the mounting bracket;

[0025] Figure 3 This is a schematic diagram showing the mounting bracket and strain sensor working together.

[0026] Figure 4 This is a schematic diagram of the hinged joint from a top view.

[0027] In the attached diagram, 1 is the monitoring instrument, 2 is the monitoring hole, 3 is the strain sensor, 4 is the temperature sensor, 5 is the fixing ring, 6 is the fixed section, 7 is the suspended section, 8 is the adjusting screw, 9 is the hinge seat, 10 is the connecting hole, 11 is the wire groove, 12 is the filling layer, 13 is the sealing cover, and 14 is the air chamber. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0029] Specific implementation examples Figure 1 , Figure 2 and Figure 3 As shown, the present invention discloses a dam structure monitoring system based on intelligent temperature and strain sensing, including a sensing unit installed in the dam foundation, the sensing unit being connected to a monitoring instrument 1, a monitoring hole 2 being pre-set in the dam foundation, the sensing unit including a fiber optic strain sensor 3 and a fiber optic temperature sensor 4, the temperature sensor 4 being installed at the bottom of the monitoring hole 2, and the strain sensor 3 being installed on the circumferential sidewall of the monitoring hole 2.

[0030] This invention employs a fiber optic strain sensor 3 and a temperature sensor 4 to construct a sensing unit. Leveraging the fiber optic strain sensor's ability to withstand high humidity and strong electromagnetic interference, it stably provides sensing parameters in the harsh service environment of the dam. Two sets of strain sensors 3 are vertically arranged using a mounting bracket, enabling them to capture strain information in multiple dimensions of the dam's sidewall. Combined with the temperature sensor 4 attached to the bottom of the monitoring hole 2, it achieves coordinated acquisition of temperature and strain parameters, overcoming the shortcomings of insufficient sensing dimensions of a single sensor and significantly improving the accuracy and data integrity of dam structural condition monitoring.

[0031] The strain sensor 3 of this invention is attached to the side wall of the monitoring hole 2. When the side wall of the monitoring hole 2 vibrates or undergoes slight deformation, the strain sensor 3 senses the deformation pressure by means of the compression of the side wall, thereby qualitatively determining whether vibration or deformation has occurred. The temperature sensor 4 is set at the bottom of the monitoring hole 2. This position is located inside the dam body where the temperature change is relatively small. However, when water seepage inside the dam body causes an increase in water content, the water will cause changes in the thermal conductivity of the dam body. Since the water temperature, especially the temperature of deep water, is lower than the temperature of the dam body, the data from the temperature sensors 4 set at multiple locations on the dam body can be compared to qualitatively determine whether there is a risk of water seepage and provide timely early warning information.

[0032] Furthermore, the strain sensor 3 is mounted on the circumferential sidewall of the monitoring hole 2 using a mounting bracket. The mounting bracket includes a fixing ring 5 and a transmission mechanism disposed within the fixing ring 5. The transmission mechanism includes a transmission rod, the fixed section 6 of which is fixedly connected to the inner sidewall of the fixing ring 5, and the other end is a suspended section 7. Two sets of transmission rods are centrally symmetrically arranged with respect to the center of the fixing ring 5. The strain sensor 3 is rod-shaped and fixed between the suspended sections 7 of the two sets of transmission rods.

[0033] The present invention uses a fixing ring 5 to install the strain sensor 3 in the monitoring hole 2. The fixing ring 5 deforms under the stress of the monitoring hole 2, and then transmits the stress to the strain sensor 3 through the transmission rod, so that the strain sensor 3 can acquire data. The installation of the mounting bracket simplifies the layout process of the monitoring system, eliminating the need for a permanent fixing structure in the monitoring hole 2, which facilitates rapid deployment and reduces the workload of subsequent maintenance, as well as facilitating subsequent replacement and upgrades.

[0034] Furthermore, such as Figure 2 and Figure 3 As shown, the fixed section 6 and the suspended section 7 of the transmission rod are integrally arranged in an L-shape. The transmission mechanism also includes an adjusting screw 8, which is connected between the suspended sections 7 of the two sets of transmission rods. The connection point of the adjusting screw 8 is hinged to the suspended section 7. The distance from the connection point to the connection point between the suspended section 7 and the fixed section 6 is less than the distance from the connection point to the end of the suspended section 7.

[0035] The suspended sections 7 of the two sets of transmission rods form a lever structure with the help of the adjusting screw 8. When the fixed section 6 pushes or pulls the suspended section 7 with the deformation of the fixed ring 5, the two ends of the suspended section 7 move with the hinge point of the adjusting screw 8 as the fulcrum, which can amplify the degree of deformation and help improve the monitoring range of the strain sensor 3.

[0036] The adjusting screw 8 includes forward and reverse threaded rods and threaded sleeves on both sides. The threaded sleeves are hinged to the suspended section 7. When it is necessary to adjust the length of the adjusting screw 8, the forward and reverse threaded rods are rotated to change the sleeve length with the threaded sleeves, thereby adjusting the distance between the ends of the suspended section 7, which facilitates the installation of the strain sensor 3.

[0037] Furthermore, a notched thinning groove is provided at the junction where the fixed section 6 and the suspended section 7 connect. The thinning groove makes it easier for the fixed section 6 and the suspended section 7 to deform, and the thinning groove is set in the vertical direction along the plane of the transmission rod. With the help of the thinning groove, the swing direction of the suspended section 7 is guided to be in the plane of the transmission rod. The two sets of transmission rods are set in the same plane, which makes the stress transmitted to the strain sensor 3 more accurate.

[0038] Furthermore, a hinge seat 9 is provided at the end of the suspended section 7. The hinge seat 9 has an L-shaped sheet structure. One end of the hinge seat 9 is hinged to the end of the suspended section 7, and the other end of the hinge seat 9 is provided with a connection hole 10 and a wire groove 11.

[0039] The hinge seat 9 is L-shaped, which moves the installation position of the strain sensor 3 outward, avoiding interference with the adjusting screw 8.

[0040] The strain sensor 3 has expanded flange-shaped pulling heads on both sides, which are fixedly connected to the pulling heads by means of the hinge seat 9. Multiple connecting holes 10 are provided and arranged around the wire groove 11. The wire groove 11 is connected to the edge of the side of the hinge seat 9 to form an open groove structure.

[0041] Meanwhile, the wire grooves 11 set on both sides of the strain sensor 3 provide a routing channel for the optical fiber, which facilitates installation.

[0042] This invention also discloses an installation method for a dam structure monitoring system based on intelligent temperature strain sensing, comprising the following steps:

[0043] S1. Install a sensing unit inside the monitoring hole 2 at the location to be monitored;

[0044] S2. After installation, fill the monitoring hole 2 with polyurethane foam, and bury the sensing unit with the filling layer 12 formed by the polyurethane foam.

[0045] S3. Use weather-resistant adhesive to attach the sealing cover 13 to the opening of the monitoring hole 2, lead the connecting optical fiber of the sensing unit out from the through hole reserved in the sealing cover 13, and seal the through hole with weather-resistant adhesive.

[0046] S4. Connect the optical fiber to the monitoring instrument 1, and monitor the dam structure through the monitoring instrument 1.

[0047] In step S1, the monitoring hole 2 is set as a circular hole, the fixing ring 5 is coaxially arranged inside the monitoring hole 2, the outer wall of the fixing ring 5 abuts and limits the inner wall of the monitoring hole 2, and the gap between the fixing ring 5 and the inner wall of the monitoring hole 2 is filled with adhesive.

[0048] After the fixing ring 5 is placed, an adjustment model with the same external dimensions as the strain sensor 3 is installed between the two sets of hinge seats 9. The length of the adjusting screw 8 is adjusted so that the distance between the hinge seats 9 on the two sets of transmission rods is in contact with the flanges reserved at both ends of the strain sensor 3. Then the adjustment model is removed and the strain sensor 3 is installed on the hinge seats 9 with the adjusted spacing.

[0049] In step S2, a gap is left between the polyurethane foam filling layer 12 and the sealing cap 13 to form a closed air cavity 14. The sealing cap 13 has a pre-set air injection hole that communicates with the air cavity 14. According to the preset maintenance cycle, the air cavity 14 is inflated to the set pressure through the air injection hole. If the pressure holding time is less than the set value, the sealing cap 13 needs to be opened to inspect and repair the sealing cap 13 and the internal filling layer 12 to prevent water from entering.

[0050] This invention employs a double-sealing design: a polyurethane foam filling layer 12 buries the sensing unit, and a sealing cap 13, combined with weather-resistant adhesive, seals the opening of the monitoring hole 2. The filling layer 12 forms a reliable waterproof and moisture-proof structure, preventing moisture intrusion that could corrode the mounting bracket and fiber optic grating sensor housing. The soft material of the filling layer 12 has a negligible impact on the sensing of the strain sensor 3. Simultaneously, the air cavity 14 and air injection hole reserved between the filling layer 12 and the sealing cap 13 within the monitoring hole 2 allow for periodic pressure testing to check the sealing performance, identify potential leaks in advance, and repair them promptly, further ensuring the stability of the sensing unit's operating environment.

[0051] In step S1, the strain sensors 3 of the sensing unit are arranged in two sets at intervals with the help of the mounting bracket. The sensing directions of the two sets of strain sensors 3 are arranged perpendicularly. The temperature sensor 4 is attached and fixed on the plane at the bottom of the monitoring hole 2 with the help of adhesive.

[0052] The adhesive used in this invention is preferably cement of the same grade as the cement used at the location of the monitoring hole 2. When installing the temperature sensor 4, the bottom of the monitoring hole 2 is first roughened and dust is removed. Then, a layer of cement is applied to the bottom of the monitoring hole 2, and the temperature sensor 4 is placed on the cement layer. Cement is then added to bury the temperature sensor 4. A fixing ring 5 with a diameter slightly smaller than that of the monitoring hole 2 is placed inside the monitoring hole 2. Several dots of cement are filled between the monitoring hole 2 and the fixing ring 5. After the cement has initially set, the fixing ring 5 is temporarily fixed. Then, the length of the adjusting screw 8 is adjusted to complete the installation of the strain sensor 3. After the installation is completed, the circumference of the fixing ring 5 is completely sealed with cement, so that the side wall of the fixing ring 5 and the inner wall of the monitoring hole 2 are rigidly connected by cement, which facilitates the transmission of stress. After the two sets of strain sensors 3 and one set of temperature sensors 4 are installed and the cement has dried, expanding foam is filled and the sealing cap 13 is installed to complete the deployment of the monitoring system.

Claims

1. A dam structure monitoring system based on intelligent temperature strain sensing, comprising a sensing unit installed within the dam foundation, wherein the sensing unit is connected to a monitoring instrument (1), characterized in that: The dam foundation is provided with a monitoring hole (2), and the sensing unit includes a fiber optic strain sensor (3) and a fiber optic temperature sensor (4). The temperature sensor (4) is located at the bottom of the monitoring hole (2), and the strain sensor (3) is located on the side wall of the monitoring hole (2) in the circumferential direction.

2. The dam structure monitoring system based on intelligent temperature strain sensing according to claim 1, characterized in that: The strain sensor (3) is mounted on the side wall of the monitoring hole (2) around the mounting bracket. The mounting bracket includes a fixing ring (5) and a transmission mechanism set in the fixing ring (5). The transmission mechanism includes a transmission rod. The fixed section (6) of the transmission rod is fixedly connected to the inner side wall of the fixing ring (5), and the other end is a suspended section (7). The transmission rod is arranged in two sets symmetrically with respect to the center of the fixing ring (5). The strain sensor (3) is fixed in a rod-like structure between the suspended sections (7) of the two sets of transmission rods.

3. The dam structure monitoring system based on intelligent temperature strain sensing according to claim 2, characterized in that: The fixed section (6) and the suspended section (7) of the transmission rod are integrated in an L-shape. The transmission mechanism also includes an adjusting screw (8). The adjusting screw (8) is connected between the suspended sections (7) of the two sets of transmission rods. The connecting point of the adjusting screw (8) is hinged to the suspended section (7). The distance from the connecting point to the connection point between the suspended section (7) and the fixed section (6) is less than the distance from the connecting point to the end of the suspended section (7).

4. The dam structure monitoring system based on intelligent temperature strain sensing according to claim 3, characterized in that: A notched thinning groove is provided at the junction where the fixed section (6) and the suspended section (7) connect.

5. The dam structure monitoring system based on intelligent temperature strain sensing according to claim 2, characterized in that: The suspended section (7) is provided with a hinge seat (9) at its end. The hinge seat (9) has an L-shaped sheet structure. One end of the hinge seat (9) is hinged to the end of the suspended section (7). The other end of the hinge seat (9) is provided with a connection hole (10) and a wire groove (11).

6. The dam structure monitoring system based on intelligent temperature strain sensing according to claim 5, characterized in that: Multiple connecting holes (10) are provided and arranged around the wire groove (11). The wire groove (11) is connected to the edge of the side of the hinge seat (9) to form an open groove structure.

7. An installation method for a dam structure monitoring system based on intelligent temperature strain sensing, based on the dam structure monitoring system based on intelligent temperature strain sensing as described in claim 1, characterized in that: The method includes the following steps. S1. Install a sensing unit inside the monitoring hole (2) at the location to be monitored; S2. After installation, fill the monitoring hole (2) with polyurethane foam and bury the sensing unit with the filling layer (12) formed by the polyurethane foam. S3. Use weather-resistant adhesive to attach a sealing cap (13) to the opening of the monitoring hole (2), lead the connecting optical fiber of the sensing unit out from the through hole reserved in the sealing cap (13), and seal the through hole with weather-resistant adhesive. S4. Connect the optical fiber to the monitoring instrument (1) and monitor the dam structure through the monitoring instrument (1).

8. The installation method of the dam structure monitoring system based on intelligent temperature strain sensing according to claim 7, characterized in that: In step S1, the monitoring hole (2) is set as a circular hole, and the fixing ring (5) is coaxially set inside the monitoring hole (2). The outer wall of the fixing ring (5) abuts against the inner wall of the monitoring hole (2) and limits its movement. The gap between the fixing ring (5) and the inner wall of the monitoring hole (2) is filled with adhesive. After the fixing ring (5) is placed, an adjustment model with the same external dimensions as the strain sensor (3) is installed between the two sets of hinge seats (9). The length of the adjusting screw (8) is adjusted so that the distance between the hinge seats (9) on the two sets of transmission rods is in contact with the flanges reserved at both ends of the strain sensor. Then the adjustment model is removed and the strain sensor (3) is installed on the hinge seats (9) with the adjusted spacing.

9. The installation method of the dam structure monitoring system based on intelligent temperature strain sensing according to claim 7, characterized in that: In step S2, a closed air cavity (14) is formed by a gap between the polyurethane foam filling layer (12) and the sealing cap (13). The sealing cap (13) has an air injection hole that communicates with the air cavity (14). According to the preset maintenance cycle, the air cavity (14) is filled with air to the set pressure through the air injection hole. If the pressure holding time is less than the set value, the sealing cap (13) needs to be opened to inspect and repair the sealing cap (13) and the filling layer (12) inside to prevent water from entering.

10. The installation method of the dam structure monitoring system based on intelligent temperature strain sensing according to claim 7, characterized in that: In step S1, the strain sensors (3) of the sensing unit are arranged in two sets at intervals by means of the mounting bracket. The sensing directions of the two sets of strain sensors (3) are arranged perpendicularly. The temperature sensor (4) is attached and fixed on the plane at the bottom of the monitoring hole (2) by means of adhesive.

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