Multi-layer coating pre-buried PCCP corrosion monitoring system and monitoring method based on three electrodes and strain rosette array

Abstract

The invention discloses a multi-layer coated pre-buried PCCP corrosion monitoring system based on three electrodes and a strain rosette array, the system comprises a working electrode, a reference electrode and a counter electrode, the working electrode is connected to a steel wire of a PCCP, the reference electrode is placed on a mortar layer of a PCCP pipe, the counter electrode is arranged in the mortar layer, the three electrodes are led out by using a copper lead, and the three electrodes are connected with the working electrode. A plurality of strain rosettes are mounted on the surface of the mortar layer, a WO3 electrochromic coating is sprayed on the surface of the mortar layer, and a conductive layer is sprayed on the WO3 electrochromic coating. According to the multi-layer coating pre-buried PCCP corrosion monitoring system and monitoring method based on the three-electrode and strain rosette array, through the synergistic effect of the pre-buried three-electrode system, the strain rosette sensor and the multi-layer functional coating, the purposes of real-time corrosion monitoring, self-early warning and long-term PCCP protection are achieved.

Description

Technical Field

[0001] The present invention relates to a multi-layer coated embedded PCCP corrosion monitoring system and a monitoring method based on a three-electrode and strain rosette array, belonging to the technical field of corrosion monitoring. Background Art

[0002] As the core pipe material for long-distance water conveyance projects, most PCCPs are buried underground. Due to the lack of effective monitoring means, once corrosion problems occur, it is necessary to frequently excavate the ground for inspection and repair. This not only consumes a large amount of human, material and time costs, but also the excavation process may damage the surrounding environment and other underground facilities. For example, in urban municipal pipe networks, excavation operations may damage roads, affect traffic, and even dig off other important underground pipelines such as cables and communication optical cables, causing great inconvenience and additional losses.

[0003] Traditional PCCP corrosion monitoring mostly uses single electrochemical sensors or strain gauges. However, in the actual complex environment, single electrochemical sensors are extremely vulnerable to environmental factors such as various chemical substances in the soil, changes in moisture content, and microbial activities. For example, the electrolyte composition in the soil is complex and variable, and the soil pH value in different regions may fluctuate greatly between 4 and 10, which will seriously affect the electrode reaction of the sensor, resulting in low measurement accuracy and inability to accurately reflect the true corrosion state of the pipeline. Strain gauges are extremely sensitive to temperature changes. In areas with large day-night temperature differences, the temperature difference can reach more than 30°C. The thermal expansion and contraction caused by temperature changes will cause large temperature drifts in the strain gauges, resulting in measurement errors and inability to accurately capture the changes in the mechanical properties of the pipeline caused by corrosion.

[0004] In the prior art, the coating protection and monitoring functions are independent of each other. The protective coating mainly focuses on physical isolation to prevent external corrosive media from contacting the pipeline body, but it cannot provide real-time feedback on where the corrosion starts on the pipeline and how the corrosion degree develops. For example, the common asphalt coating can delay corrosion to a certain extent, but when the coating is locally damaged, it cannot detect the starting point and spreading range of corrosion in time, cannot realize the visualization positioning of the corrosion area, and it is difficult to carry out targeted maintenance and repair.

[0005] Therefore, there is an urgent need to develop an embedded pipeline corrosion controllable test device that can accurately simulate the corrosion damage behavior during the actual operation of PCCP, integrate functions such as corrosion coating protection, and provide a reliable test platform for revealing the corrosion failure mechanism of pipelines in complex environments. Summary of the Invention

[0006] Objective of the Invention: In order to overcome the deficiencies in the prior art, the present invention provides a multi-layer coated embedded PCCP corrosion monitoring system and monitoring method based on a three-electrode and strain rosette array. Through the synergistic effect of the embedded three-electrode system, strain rosette sensors and multi-layer functional coatings, the objectives of real-time corrosion monitoring, self-warning and long-term protection of PCCP are achieved.

[0007] Technical Solution: To solve the above technical problems, a multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array of the present invention includes a working electrode, a reference electrode and a counter electrode. The working electrode is connected to the steel wire of the PCCP, the reference electrode is placed in the mortar layer of the PCCP pipe, the counter electrode is arranged in the mortar layer, and copper wires are used to lead out the three electrodes. A number of strain rosettes are installed on the surface of the mortar layer, a WO3 electrochromic coating is sprayed on the surface of the mortar layer, and a conductive layer is sprayed on the WO3 electrochromic coating.

[0008] Preferably, the conductive layer is a PEDOT conductive polymer.

[0009] Preferably, the three electrodes are used to obtain the distribution of local corrosion current density. The strain rosettes synchronously respond to local microcracks and strain changes induced by corrosion, realizing the collaborative analysis of mechanical and electrical signals. Through the electrochemical and mechanical coupling layout method, the ability to identify early corrosion damage is enhanced, which helps to achieve a higher-resolution corrosion source location. Among them, the positions of the reference electrode and the counter electrode relative to the working electrode can be flexibly adjusted according to the target corrosion area to improve the monitoring accuracy; the layout method of the strain rosette array can be flexibly adjusted.

[0010] In this solution, an equal-spacing and variable-spacing fusion layout scheme is adopted: The equal-spacing layout can be used as a basic reference model for the preliminary sensitivity evaluation of the system, the verification of the monitoring area coverage and the balanced design of the signal channels. After obtaining the preliminary monitoring data and completing the structural finite element simulation analysis, for the identified high-stress concentration areas or high-corrosion gradient sections, a variable-spacing layout strategy is further adopted for optimization and adjustment. When using variable-spacing layout, sensors are encrypted in high-stress or high-corrosion gradient areas to improve the strain capture resolution, and moderately sparsely arranged in low-gradient areas to reduce redundancy and improve the system resource utilization rate. The coordinates of the working electrode are: (x, y, z), x = rcosθ, y = rsinθ, z = np, then the position of the reference electrode can be expressed as: (x1, y1, z1) = (r + 0.01cosθ, r + 0.01sinθ, z), and the position of the counter electrode is (x2, y2, z2) = (r + 0.02cosθ, r + 0.02sinθ, z). The central coordinates of the working area of the three-electrode system are (x ele [[ID=!4]], y ele , z ele), the strain rosettes are arranged in an equidistant manner around the working area of the three-electrode system along the x-direction. Assuming that the x-direction spacing is Δx, n strain rosettes are arranged in the x-direction. x So the coordinates of the rosette in the nth column are: To achieve high-precision strain monitoring in high-risk corrosion areas, this solution introduces a variable spacing strategy driven by stress gradients, based on the initial equal spacing. The sensor spacing setting is inversely proportional to the local stress gradient, as expressed by:

[0011]

[0012] A monitoring method for a multi-layer coated pre-buried PCCP corrosion monitoring system based on three electrodes and a strain gauge rosette array comprises the following steps:

[0013] S1: Prepare the PCCP foundation components, sequentially preparing the concrete core, welding the steel cylinder, and winding the prestressed steel wire. Select a suitable three-electrode system for burial, treating the prestressed steel wire as the working electrode and welding with a wire. The reference electrode is encapsulated, and a stainless steel plate close to the working area is selected for the counter electrode. Based on the structural characteristics of the PCCP pipeline and analysis of previous corrosion cases, a burial location is selected every 0.5m-1m in the axial direction of the pipeline, and good electrical connection is ensured at each burial location.

[0014] S2: Roller-spray the outer layer of mortar onto the pipeline. Place the reference electrode in the predetermined hole in the mortar layer. Install and fix the counter electrode in the mortar layer. Use copper wires to weld and connect the three electrodes. Lead the wires through the pipe embedded in the concrete core to a specific location on the outer surface of the pipeline. Install a waterproof sealing joint at the lead-out location. Finally, connect the wires to the electrochemical workstation for preliminary monitoring.

[0015] S3: Based on the buried position of the three-electrode system, determine the placement of the strain rosette on the surrounding mortar layer surface. With the three-electrode system as the center, mark the patch positions of the strain rosette according to a certain grid layout within a radius of 50-100mm. At the marked patch positions, use sandpaper to polish the mortar layer surface, then wipe the surface with alcohol or acetone. Apply a layer of epoxy resin structural adhesive with a thickness of 0.2-0.3mm evenly on the treated surface. After the epoxy resin structural adhesive is initially cured, use 502 glue to accurately attach the metal foil strain rosette 3 to the marked position. Solder the wires of the strain rosette to the pre-arranged signal transmission line and fix the wires along the mortar surface with tape. Finally, connect the signal transmission lines of all strain rosettes to the data acquisition device.

[0016] S4: Prepare a WO3 electrochromic coating suitable for spraying by the sol-gel method. Before spraying, clean the surface of the mortar layer. Use a spray gun to evenly spray the WO3 electrochromic coating on the outer surface of the mortar layer. Adopt the method of multiple sprays. Control the spraying pressure at 0.3 - 0.5 Mpa, the temperature at 20 - 25 °C, and the relative humidity at 40% - 60%. After spraying, cure the pipeline.

[0017] S5: Select PEDOT conductive polymer as the spraying material. After spraying, reduce the driving voltage to 1 - 2 V.

[0018] S6: Install a high-precision multispectral camera on the unmanned aerial vehicle, and transmit the collected image data back to the ground control center in real time. Use image recognition algorithms to identify whether there is a blue area in the WO3 electrochromic layer, obtain the accurate position information of this area through the GPS positioning system, and combine with the geographical information system GIS data of the pipeline to mark the position of the potential corrosion damage area on the map.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0020] (1) Improvement in comprehensive monitoring performance: By reasonably arranging the working electrode, reference electrode, and counter electrode, it can monitor the changes in electrochemical parameters of the pipeline environment in real time and accurately, providing key electrochemical data for evaluating corrosion risks and timely discovering potential corrosion hazards. Laying a strain gauge array closely around the three-electrode system can effectively monitor the stress changes caused by factors such as pipeline stress and deformation during the operation of the three-electrode system, and can comprehensively judge the safety of the pipeline.

[0021] (2) Efficient corrosion warning and positioning: When the WO3 electrochromic layer receives an abnormal potential signal, it can quickly change from transparent to blue, indicating the possible corrosion area in an intuitive and visual way. Compared with traditional corrosion monitoring methods, it does not require complex data analysis and professional detection equipment, and can directly observe the color change on the pipeline surface, quickly determine the approximate location where corrosion occurs, greatly improving the timeliness and accuracy of corrosion warning.

[0022] (3) Optimization of coating performance and functions: Using an unmanned aerial vehicle equipped with a multispectral camera, based on its sensitivity to specific bands, it can quickly and widely identify the blue area presented by the WO3 electrochromic layer. Inspect a large area of the pipeline in a short time, overcoming the disadvantages of low efficiency and limited scope of manual inspection. At the same time, through precise positioning technology, it can efficiently locate potential corrosion areas, providing accurate position information for subsequent maintenance and repair work, greatly reducing maintenance costs and time costs. Description of the Drawings

[0023] Figure 1 Embedded PCCP Corrosion Monitoring Test Method Based on Sensor and Multilayer Coating Fusion

[0024] Figure 2 Schematic Diagram of Embedded Structure of PCCP Monitoring Sensor

[0025] Figure 3 Schematic Diagram of Planar Position of PCCP Monitoring Sensor

[0026] In the figure: PCCP pipeline 1; mortar protective layer 11; prestressed steel wire 12; electrochemical workstation 2; three - electrode system 21; strain gage array 3; WO3 electrochromic layer and PEDOT conductive layer 4 Specific Embodiment

[0027] The present invention will be further described below with reference to the accompanying drawings

[0028] As Figures 1 to 3 shown, a multi - layer coated embedded PCCP corrosion monitoring system based on a three - electrode and strain gage array includes a working electrode, a reference electrode, and a counter electrode. The working electrode is connected to the steel wire of the PCCP, the reference electrode is placed in the mortar layer of the PCCP pipe, the counter electrode is arranged in the mortar layer, and copper wires are used to lead out the three electrodes. A number of strain gages are installed on the surface of the mortar layer, WO3 electrochromic coating is sprayed on the surface of the mortar layer, and a conductive layer is sprayed on the WO3 electrochromic coating

[0029] This embodiment provides a multi - layer coated embedded PCCP corrosion monitoring method based on a three - electrode and strain gage array. The specific corrosion monitoring test method corresponding to this embodiment is as Figure 1 shown, and specifically includes the following steps

[0030] Step (1): Prepare the basic components of the PCCP, and successively carry out the preparation of the concrete pipe core, welding of the steel cylinder, and winding of the prestressed steel wire. Select a suitable three - electrode system 21 for embedding, regard the prestressed steel wire 12 as the working electrode and weld it with a wire; the reference electrode adopts a long - life solid - state manganese dioxide electrode and is encapsulated to ensure its stable performance in the mortar environment. The counter electrode is selected as a stainless - steel plate close to the working area, with an area slightly larger than the working electrode to ensure the full progress of the electrochemical reaction. According to the structural characteristics of the PCCP pipeline and the analysis of previous corrosion cases, a burial position is selected every 0.5 m - 1 m in the axial direction of the pipeline, and good electrical connection is ensured at each burial position

[0031] Step (2): Roll-spray the outer layer of mortar 11 on the pipeline, and place the reference electrode in a predetermined hole in the mortar layer about 10 mm away from the steel wire to avoid displacement during subsequent construction. The counter electrode is installed at a position corresponding to and close to the working electrode, and is also fixed in the mortar layer 11. Use copper wires to weld and connect the three electrodes 21 separately, and the welding points are treated with waterproof and insulating welding materials to ensure that the connection is firm and the signal transmission is stable. Lead the wire through the pipeline pre-buried in the concrete pipe core to a specific position on the outer surface of the pipeline, and set a waterproof sealing joint at the lead-out position to prevent external moisture and corrosive media from entering and affecting the electrode signal transmission. Finally, connect the wire to the electrochemical workstation 2 for preliminary monitoring.

[0032] Step (3): According to the buried position of the three-electrode system 21, the laying position of the strain rosette is determined on the surface of the mortar layer 11 around it. Generally, with the three-electrode system 21 as the center, within a radius of 50-100mm, the patch position of the strain rosette 3 is marked according to a certain grid layout. At the marked patch position, use sandpaper to polish the surface of the mortar 11 to remove the surface slurry and uneven parts, so that the surface roughness meets certain requirements. Then wipe the surface with an organic solvent such as alcohol or acetone to remove impurities such as oil and dust. Evenly apply a layer of epoxy resin structural adhesive with a thickness of 0.2-0.3mm on the treated surface to fill the fine pores on the surface of the mortar 11 and improve the adhesion between the strain rosette 3 and the surface of the mortar 11. After the epoxy resin structural adhesive is initially cured, use 502 glue to accurately stick the metal foil strain rosette 3 on the marked position. Solder the wires of the strain rosette 3 to the pre-arranged signal transmission line, and encapsulate the welding points with Kraft glue to prevent the welding points from oxidation and moisture. Secure the wires along the mortar surface with tape to prevent displacement or damage during subsequent construction and use. Finally, connect the signal transmission lines of all strain gauge rosettes 3 to the data acquisition device to ensure proper signal transmission.

[0033] Step (4): Prepare a WO3 electrochromic coating suitable for spraying by using the sol-gel method. Before spraying, clean the surface of the mortar 11 to remove dust and impurities on the surface. Use a spray gun to evenly spray the WO3 electrochromic coating on the outer surface of the mortar 11, using multiple spraying methods and controlling the spraying pressure at 0.3-0.5 MPa. During the spraying process, the temperature is generally controlled at 20-25°C and the relative humidity is controlled at 40%-60% to ensure the film quality of the coating. After spraying is completed, the pipeline is cured at a certain temperature so that the coating forms a stable electrochromic layer 4.

[0034] Step (5): Select PEDOT conductive polymer as the spraying material, which has good conductivity and stability. Dilute and prepare the solution appropriately to adjust its viscosity and conductivity to make it suitable for the spraying process requirements. Precisely control the thickness by multiple sprays and controlling the spraying time. After spraying, dry the coating so that the PEDOT conductive layer firmly adheres to the WO3 electrochromic layer 4, forming a good conductive path, reducing the driving voltage to 1 - 2V, and at the same time accelerating the ion migration speed inside the coating, improving the timeliness and stability of the electrochromic response.

[0035] Step (6): Select a drone platform with good flight stability, endurance, and carrying capacity. Install a high-precision multispectral camera on the drone, which is sensitive to light in a specific band and matches the reflected light band after the WO3 electrochromic layer changes color. At the same time, equip it with a high-precision GPS positioning system and a data transmission module to ensure that the drone can accurately record its own position during flight and transmit the collected image data back to the ground control center in real time. Use image recognition algorithms to identify whether a blue area appears on the WO3 electrochromic layer 4, obtain the accurate position information of this area through the GPS positioning system, and combine the geographic information system (GIS) data of the pipeline to accurately mark the position of the potential corrosion damage area on the map. At the same time, record and analyze information such as the area and color depth of the detected corrosion damage area to provide a basis for subsequent maintenance decisions.

[0036] Among them, the determination of the three-electrode system and the strain rosette position layout will be carried out by the following methods:

[0037] (a) It is known that the steel wire is wound around the pipeline along the axial direction. Assume the radius of the pipeline is r and the pitch of the steel wire winding is p. For a certain circle of steel wire, its position in the circumferential direction of the pipeline is represented by the angle θ. First, select a point on the steel wire as the application of the working electrode, and set its coordinates as (x, y, z), and x = rcosθ, y = rsinθ, z = np. Calculate the angle θ and determine the positions of the reference electrode and the counter electrode.

[0038] (b) Place the reference electrode in the mortar layer 10 mm radially outward from the working electrode. Based on the position of the steel wire where the working electrode is located, in the cylindrical coordinate system, the position of the reference electrode can be expressed as:

[0039] (x1, y1, z1) = (r + 0.01cosθ, r + 0.01sinθ, z)

[0040] (c) Select a platinum electrode close to the working area as the counter electrode and place it in the mortar layer at a concentric circle with the same angle as the working electrode and 20 mm radially inward. Its position can be expressed as:

[0041] (x2, y2, z2) = (r + 0.02cosθ, r + 0.02sinθ, z)

[0042] (d) The strain rosette matrix is laid near the three - electrode system to monitor the stress change during the operation of the three - electrode system. Assume that the central coordinates of the working area of the three - electrode system are (x ele , y ele , z ele ). The strain rosettes are arranged in an equally - spaced distribution. Around the working area of the three - electrode system, the strain rosettes are arranged at equal intervals along the x - direction. Assume that the spacing in the x - direction is Δx, and n x strain rosettes are arranged in the x - direction. So the coordinates of the nth strain rosette are:

[0043]

[0044] (e) To achieve high - precision strain monitoring in the high - risk area of corrosion damage, based on the preliminary equally - spaced layout, this scheme introduces a variable - spacing layout strategy driven by stress gradient. The sensor spacing is set inversely proportional to the local stress gradient, and the specific expression is:

[0045]

[0046] where Δx n is the spacing between the nth and (n + 1)th strain rosettes; is the stress gradient at the position x n ; C is a normalization coefficient that controls the layout range, that is, ∑Δx n = L, where the total length is L. ε is a constant to prevent the denominator from being zero.

[0047] The above calculations are generally carried out by calculating the coordinates of the steel wires according to the distribution law of the steel wires, using the above - mentioned circumferential - direction angle and axial - position formulas. According to the coordinates of the steel wires, the coordinates of the reference electrode are calculated using polar - coordinate or rectangular - coordinate conversion formulas. Determine the central coordinates of the working area, use them as the central coordinates of the counter electrode, and determine the size of the counter electrode according to the size of the working area. According to the central coordinates of the working area of the three - electrode system, select the surrounding - layout or equally - spaced - distribution method, and use the corresponding formulas to calculate the coordinates of the strain rosettes. Through the above methods, the position layouts of the three - electrode and the strain rosettes can be calculated more accurately, providing a basis for the construction of the test device. According to the above sensor - position calculations, an equally - spaced sensor layout is planned for a 6 - meter - long PCCP pipeline, and the calculated positions are shown in the following table:

[0048] angle working electrode reference electrode counter electrode strain rosette the first group 36.87° (0.8,0.6,0.2) (0.808,0.606,0.2) (0.784,0.588,0.2) (0.7,0.6,0.2) the second group 45° (0.7,0.7,1.2) (0.707,0.707,1.2) (0.686,0.686,1.2) (0.75,0.6,0.2) the third group 53.13° (0.6,0.8,2.2) (0.603,0.797,2.2) (0.588,0.784,2.2) (0.8,0.6,0.2) the fourth group 61.55° (0.5,0.87,3.2) (0.501,0.866,3.2) (0.49,0.849,3.2) (0.85,0.6,0.2) the fifth group 66.8° (0.4,0.91,4.2) (0.4,0.916,4.2) (0.392,0.896,4.2) (0.9,0.6,0.2) the sixth group 73.3° (0.3,0.95,5.2) (0.301,0.954,5.2) (0.294,0.931,5.2) (0.95,0.6,0.2)

[0049] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array, characterized in that: The device includes a working electrode, a reference electrode, and a counter electrode. The working electrode is connected to the steel wire of the PCCP. The reference electrode is placed in the mortar layer of the PCCP tube. The counter electrode is set in the mortar layer. The three electrodes are led out using copper wires. Several strain gauge rosettes are installed on the surface of the mortar layer. WO3 electrochromic paint is sprayed on the surface of the mortar layer. A conductive layer is sprayed on the WO3 electrochromic paint.

2. The multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array according to claim 1, wherein: The conductive layer is PEDOT conductive polymer.

3. The multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array according to claim 1, characterized in that: The coordinates of the working electrode are: (x, y, z), where x = rcosθ, y = rsinθ, and z = np. The radius of the pipe is r, and the pitch of the wire winding is p. For a point on a certain turn of the wire, its position in the circumferential direction of the pipe is represented by the angle θ. Then, the position of the reference electrode is expressed as: (x1, y1, z1) = (r + 0.01cosθ, r + 0.01sinθ, z), and the position of the counter electrode is (x2, y2, z2) = (r + 0.02cosθ, r + 0.02sinθ, z). The central coordinates of the working area of the three-electrode system are (x ele , y ele , z ele ). The strain rosettes are arranged at equal intervals. Around the working area of the three-electrode system, the strain rosettes are arranged at equal intervals along the x direction. Assume the spacing in the x direction is Δx, and n x strain rosettes are arranged in the x direction. The coordinates of the strain rosette in the nth column are:

4. The multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array according to claim 3, characterized in that: The ▽σ(x n ) is the stress gradient at position x n , C is the normalization coefficient for controlling the layout range, such that ∑Δx n = L, the total length is L, and ε is a constant to prevent the denominator from being 0.

5. The monitoring method of the multi-layer coated embedded PCCP corrosion monitoring system based on the three-electrode and strain rosette array according to any one of claims 1 to 4, characterized in that, The following steps are involved: S1: Prepare the PCCP foundation components, sequentially preparing the concrete core, welding the steel cylinder, and winding the prestressed steel wire. Select a suitable three-electrode system for burial, treating the prestressed steel wire as the working electrode and welding with a wire. The reference electrode is encapsulated, and a stainless steel plate close to the working area is selected for the counter electrode. Based on the structural characteristics of the PCCP pipeline and analysis of previous corrosion cases, a burial location is selected every 0.5m-1m in the axial direction of the pipeline, and good electrical connection is ensured at each burial location. S2: Roller-spray the outer layer of mortar onto the pipeline. Place the reference electrode in the predetermined hole in the mortar layer. Install and fix the counter electrode in the mortar layer. Use copper wires to weld and connect the three electrodes. Lead the wires through the pipe embedded in the concrete core to a specific location on the outer surface of the pipeline. Install a waterproof sealing joint at the lead-out location. Finally, connect the wires to the electrochemical workstation for preliminary monitoring. S3: Based on the buried position of the three-electrode system, determine the placement of the strain rosette on the surrounding mortar layer surface. With the three-electrode system as the center, mark the patch positions of the strain rosette according to a certain grid layout within a radius of 50-100mm. At the marked patch positions, use sandpaper to polish the mortar layer surface, then wipe the surface with alcohol or acetone. Apply a layer of epoxy resin structural adhesive with a thickness of 0.2-0.3mm evenly on the treated surface. After the epoxy resin structural adhesive is initially cured, use 502 glue to accurately attach the metal foil strain rosette 3 to the marked position. Solder the wires of the strain rosette to the pre-arranged signal transmission line and fix the wires along the mortar surface with tape. Finally, connect the signal transmission lines of all strain rosettes to the data acquisition device. S4: A WO3 electrochromic coating suitable for spraying is prepared by a sol-gel method. Before spraying, the surface of the mortar layer is cleaned. The WO3 electrochromic coating is evenly sprayed on the outer surface of the mortar layer using a spray gun. Multiple spraying is performed. The spraying pressure is controlled at 0.3-0.5 MPa, the temperature is controlled at 20-25°C, and the relative humidity is controlled at 40%-60%. After spraying, the pipeline is cured. S5: Select PEDOT conductive polymer as the spraying material. After spraying, reduce the driving voltage to 1-2V. S6: Install a high-precision multispectral camera on the UAV, and transmit the collected image data back to the ground control center in real time. Use image recognition algorithms to identify whether a blue area appears in the WO3 electrochromic layer, obtain the accurate location information of this area through the GPS positioning system, and combine with the geographic information system (GIS) data of the pipeline to mark the location of the potential corrosion damage area on the map.

6. The monitoring method of the multi-layer coated embedded PCCP corrosion monitoring system based on a three-electrode and strain rosette array according to claim 5, characterized in that: The reference electrode is solid manganese dioxide.

Images