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CN-122013195-A - Nondestructive rapid detection method for cathode protection effect of PCCP pipeline in HM water supply engineering

CN122013195ACN 122013195 ACN122013195 ACN 122013195ACN-122013195-A

Abstract

The invention discloses a nondestructive rapid detection method for the cathode protection effect of a PCCP pipeline in an HM water supply project, and belongs to the technical field of corrosion protection and nondestructive detection of buried metal pipelines. The method solves the problem that the measurement result is seriously distorted due to the high resistance characteristic of the PCCP pipeline concrete protection layer in the traditional potential measurement method. According to the method, a distributed optical fiber current sensing unit is adopted to continuously measure protection current density distribution along the axial direction of a pipeline in a non-contact mode, an actually measured current density sequence is used as a dynamic boundary condition to be input into a pre-constructed PCCP (prestressed concrete cylinder pipe) multi-layer structure current potential field coupling inversion model, a coupling physical field equation set is solved to directly invert and calculate a true polarization potential distribution map of the surface of a steel cylinder under a concrete layer, and full-line protection effect evaluation and accurate positioning of a risk section are achieved through comparison with a preset protection potential standard. The invention can diagnose the effectiveness and evaluate the risk of the PCCP pipeline in the in-service water supply engineering without cutting off the water and excavating the fast full-line cathode protection.

Inventors

  • XING WEIWEI

Assignees

  • 中电建路桥集团有限公司

Dates

Publication Date
20260512
Application Date
20251217

Claims (10)

  1. 1. The nondestructive rapid detection method for the cathodic protection effect of the PCCP pipeline in the HM water supply engineering is characterized by comprising the following steps of: S1, measuring distributed axial protection current density, namely axially arranging distributed optical fiber current sensing units along the outer wall surface or under a soil covering layer of a PCCP pipeline to be measured, wherein the distributed optical fiber current sensing units perform non-contact and uninterrupted continuous sensing on an axial circumferential magnetic field generated by a steel cylinder cathode protection current in the PCCP pipeline based on Faraday magneto-optical effect, so that an axial protection current density data sequence which is continuously distributed along the pipeline axial direction and is related to time is acquired and recorded in real time; s2, constructing a PCCP pipeline current-potential field coupling inversion model, namely constructing a multi-layer physical field finite element model comprising a steel cylinder, a prestressed steel wire, a concrete protective layer, an anticorrosive layer and a soil medium based on actual structural parameters, material attribute parameters and environmental parameters of the PCCP pipeline; S3, carrying out distributed inversion calculation on the real polarization potential of the steel cylinder, namely running a current-potential field coupling inversion model, carrying out real-time inversion calculation on the real polarization potential inside the concrete protection layer and the real polarization potential outside the steel cylinder by solving a coupling equation set of the current field and the potential field under a dynamic boundary condition, and generating a real polarization potential map which is continuously distributed along the axial direction of the pipeline; S4, comprehensively evaluating and positioning the cathodic protection effect, namely comparing the true polarization potential map obtained by inversion in the step S3 with a preset cathodic protection effective potential standard interval point by point, identifying and positioning a pipeline section with a potential value falling outside the standard interval, namely judging the pipeline section to be a cathodic protection failure or under-protection risk section, and outputting a comprehensive evaluation report containing the geographical position and the risk level of the risk section.
  2. 2. The method for nondestructive rapid detection of the cathodic protection effect of a PCCP pipeline in a water supply works of claim 1, further comprising, between steps S2 and S3, a model on-line calibration step, specifically: At least two potential verification points of known spatial positions are distributed along the line of the PCCP pipeline to be tested, and the actual measurement real polarization potential of the outer surface of the steel cylinder at each potential verification point is directly measured through an embedded reference electrode which is embedded or minimally invasive, and the actual measurement real polarization potential of each potential verification point is compared with the calculated potential value of the corresponding position obtained by inversion based on the initial model parameters and the current density data; dynamically correcting dielectric electrical parameters of a region adjacent to a potential verification point in the current-potential field coupling inversion model through an optimization algorithm based on deviation generated by comparison until the error between a calculated potential value and an actually measured real polarization potential is smaller than a set threshold value, so that a calibrated high-precision coupling inversion model is obtained; And in step S3, performing distributed inversion calculation of the true polarization potential of the steel cylinder by using the calibrated high-precision coupling inversion model.
  3. 3. The nondestructive rapid detection method for the cathodic protection effect of PCCP pipeline in water supply engineering at HM of claim 2, further comprising, after step S4, the steps of: S5, constructing a digital twin model, namely constructing a reference digital twin model consistent with the current actual pipeline protection state based on the current-potential field coupling inversion model constructed in the step S2 and optimized by the model on-line calibration step between the step S2 and the step S3 and combining the current state data acquired in the step S1 and the evaluation report output by the step S4; s6, simulating virtual intervention and effects, namely parameterizing and defining at least one cathode protection system intervention measure to be implemented in an operation interface of a reference digital twin model, wherein the intervention measure comprises adding an auxiliary anode, adjusting output parameters of a potentiostat and locally repairing an anticorrosive layer; S7, scheme comparison and optimization, namely comparing, analyzing and simulating the predicted real polarization potential distribution map under each intervention scheme, evaluating the effect of each scheme on eliminating the original risk section, evaluating whether a new underprotection or oversprotection risk area is caused in the whole range, selecting a recommended intervention scheme from the simulated schemes according to a preset technical and economic optimization target, and outputting a simulation effect report and key construction parameters of the scheme.
  4. 4. The method for nondestructive testing of PCCP pipeline cathodic protection effect in HM water supply engineering according to claim 1, wherein step S1 further comprises performing distributed axial protection current density measurement while performing non-contact multi-frequency impedance spectrum measurement along the pipeline axial direction synchronously to obtain complex impedance spectrum data sequence of each measuring point on the pipeline outer wall surface; in the step S4, the comprehensive evaluation and positioning further comprises the steps of inputting the complex impedance spectrum data sequence into a pre-trained wire breakage identification model, and obtaining a pre-stress steel wire breakage probability and a density distribution map along the axial direction of the pipeline; carrying out space superposition and association analysis on the broken wire probability and density distribution spectrum and the real polarization potential spectrum; Based on the correlation analysis result, the failure mode types of the under-protection risk section caused by the current shielding effect caused by the broken pre-stress steel wire and the under-protection risk section caused by the insufficient output of the cathode protection system are identified and distinguished.
  5. 5. The method for nondestructive rapid detection of the cathodic protection effect of a PCCP pipeline in a water supply engineering at HM of claim 4, wherein in step S4, after obtaining the probability of wire breakage and the density distribution map and before performing spatial superposition and correlation analysis, further comprises the steps of model field verification and adaptive optimization, specifically: selecting at least two representative site verification points based on the broken wire probability, the density distribution map and the real polarization potential map; For each site verification point, acquiring a real physical state verification result of the prestressed steel wire at the point by a minimally invasive detection or internal video inspection mode; comparing the real physical state verification result with an initial diagnosis result output by the broken wire identification model aiming at the point to generate a model precision evaluation report; If the comparison error exceeds a preset threshold, forming an incremental training sample set by the field verification point and a corresponding real physical state verification result thereof and original complex impedance spectrum data, and carrying out field incremental learning and parameter fine adjustment on the pre-trained broken wire identification model; And re-processing the complex impedance spectrum data sequence by utilizing the fine-tuning optimized broken wire identification model to generate an updated broken wire probability and density distribution map which is more suitable for the specific conditions of the current tested pipeline, and the updated broken wire probability and density distribution map is used for subsequent spatial superposition and correlation analysis.
  6. 6. The nondestructive rapid detection method for the cathodic protection effect of the PCCP pipeline of the water supply engineering at HM of claim 1, wherein step S1 comprises the following concrete sub-steps: S1a, vehicle-mounted magnetic anomaly quick general investigation, namely driving a detection vehicle carrying a multichannel high-precision fluxgate sensor array to travel at a constant speed along a pipeline route at a speed of not less than twenty kilometers per hour on the ground right above a PCCP pipeline to be detected; S1b, intelligently positioning a protection current density abnormal section, namely rapidly calculating and identifying a protection current density distribution trend along the axial direction of a pipeline based on a surface magnetic field intensity map through a magnetic field-current inversion algorithm, and positioning a suspected abnormal section with obvious mutation, attenuation or distortion of the current density, wherein the length range of the suspected abnormal section is 50-200 meters; And S1c, optimally arranging the distributed optical fiber sensing units, namely accurately arranging the distributed optical fiber current sensing units only in each suspected abnormal section positioned in the step S1b and the extension range of 50 meters above and below the suspected abnormal section, and for the part which is not marked as the suspected abnormal section in the whole pipeline, not arranging the distributed optical fiber current sensing units and only keeping the surface magnetic field census data obtained in the step S1a as background references.
  7. 7. The method for nondestructive rapid detection of the cathodic protection effect of a PCCP pipeline in a water supply engineering at HM of claim 1, further comprising the steps of data fusion and unified space-time archive construction after completing the comprehensive evaluation and positioning of step S4, specifically: The method comprises the steps of establishing a digital pipeline file uniquely associated with a PCCP pipeline to be tested, wherein all source data and derivative data generated by the detection are synchronously stored in the digital pipeline file in a unified data structure, wherein the digital pipeline file supports multidimensional data associated inquiry, comparison analysis and visual display based on space positions and time, and the digital pipeline file comprises a space geographic coordinate, an acquisition time stamp, an axial protection current density original value, multi-frequency impedance spectrum original data, surface magnetic field data, a true polarization potential obtained by inversion calculation, a broken wire diagnosis result, model calibration parameters, analog prediction data and the comprehensive evaluation report of each measurement point.
  8. 8. The method for nondestructive rapid detection of the cathodic protection effect of a PCCP pipeline in an HM water supply project according to claim 7, further comprising a long-term trend analysis and early warning step after the construction of the digitized pipeline file, specifically comprising: extracting true polarization potential and broken wire density data obtained by previous detection on the same spatial position point in the digital pipeline file according to time sequence; respectively constructing a potential attenuation trend prediction model and a broken wire development rate prediction model based on time sequence data; when the prediction model indicates that the potential value of a specific section is about to fall below a protection standard threshold value within a preset period of time or the broken wire density is about to exceed a safety threshold value, the system automatically generates early warning and alarming information and identifies a key time node of risk evolution.
  9. 9. The method for nondestructive rapid detection of the cathodic protection effect of a PCCP pipeline in a water supply engineering at HM of claim 4, further comprising a step of quantitative analysis of the contribution of the root cause of failure, specifically for the under-protection risk segment identified in step S4: Aiming at the under-protection risk section, constructing a multi-scenario simulation contrast model based on a current-potential field coupling inversion model; The multi-scenario simulation comparison model respectively simulates and calculates the protection potential distribution under the condition that only the current diagnosis wire breakage state exists, only the actual measurement environment medium parameter exists and other single hypothesis failure factors exist; and (3) quantitatively evaluating independent contribution degree and coupling contribution degree of the wire breakage factors, the environmental medium factors and other factors to the current potential attenuation result by comparing the simulation results with the fitness difference of the actually measured potential distribution obtained by inversion in the step (S3), and generating a root cause quantitative analysis report.
  10. 10. The nondestructive rapid detection method of the cathodic protection effect of the PCCP pipeline of the HM water supply project of claim 6, wherein in step S1b, the magnetic field-current inversion algorithm further fuses known geological survey data along the pipeline with historical excavation records; The intelligent positioning process carries out environment interference filtering and geological stratification correction on the magnetic field intensity map according to the fused data, and carries out credibility weighting on suspected abnormal sections positioned by an algorithm according to the spatial positions of known defects or interference points in the history record; Outputting a suspected abnormal section list with different confidence levels and corresponding decision suggestions, wherein the decision suggestions comprise immediately performing optical fiber detailed examination on a high-confidence section, supplementing near-distance magnetic measurement or geological radar scanning on a medium-confidence section suggestion, and marking a low-confidence section as a long-term monitoring attention point.

Description

Nondestructive rapid detection method for cathode protection effect of PCCP pipeline in HM water supply engineering Technical Field The invention relates to the technical field of corrosion protection and nondestructive detection of buried metal pipelines. More particularly, the invention relates to a nondestructive rapid detection method for the cathodic protection effect of a PCCP pipeline in an HM water supply project. Background In the prior art, the detection of the cathodic protection effect of PCCP pipelines in HM water supply engineering mainly faces the problems that firstly, a widely adopted pipe ground potential measurement method, such as a closed-circuit potential method or a potential gradient method, has the measured value significantly influenced by the high resistance of a concrete protection layer of the PCCP pipeline, and serious IR drop errors are generated. This results in the measured earth's surface potential not truly reflecting the polarization potential of the internal steel cylinder, resulting in erroneous judgment of the protection state. The root cause is that the steel cylinder is wrapped in the concrete with poor conductivity, and the traditional method is difficult to penetrate the dielectric layer for direct measurement. The difficulty in solving this problem is how to obtain a direct or indirect physical quantity capable of representing the actual electrochemical state of the steel cylinder under the conditions of continuous water and no excavation. Secondly, in order to improve the evaluation accuracy, some methods attempt to build a numerical model for inversion calculation. However, the key parameters required by the model, such as soil resistivity, concrete conductivity, and the like, have space-time variability in engineering sites. The use of fixed or design parameters can lead to model distortion, making the inversion result unreliable. The difficulty is how to economically and conveniently acquire and update these dynamic parameters in complex non-laboratory environments to maintain long term accuracy of the model. Furthermore, when detecting an underprotected area, it is a difficult problem how to choose the optimal maintenance or intervention. The effect of different measures, such as increasing the anode or adjusting the output, on the full line protection potential distribution is complex and global. Conventional empirical decision methods cannot quantitatively evaluate the specific effects of each regimen in advance, and cannot predict what negative interference it may have with other segments of the pipeline, for example, resulting in far-end over-protection or under-protection. This gives the option of a maintenance solution with trial and error properties, possibly with cost wastage or new risks. In addition, structural damage to PCCP piping, particularly pre-stressed wire breakage, is closely related to cathodic protection failure. However, existing nondestructive detection technologies, such as transient electromagnetic methods, mainly focus on the identification of broken wires, whereas conventional cathodic protection detection only evaluates potential. The two techniques are independent of each other, resulting in an inability to explicitly answer the critical engineering question of "whether a found broken wire has caused the regional cathodic protection failure" in the inspection report. The difficulty in effectively correlating the two is that there is no means for synchronously acquiring structural state and electrochemical state data and performing coupling analysis under the same space-time reference. Finally, from an engineering implementation perspective, comprehensive detection of long-distance pipelines is required to be efficient and as little as possible to affect normal operation. The traditional high-precision detection method often needs to densely arrange sensors or measure point by point, and is long in time consumption and contradicts the requirement of continuous operation of a water supply project. On the premise of ensuring the detection precision, the method greatly shortens the field operation time and reduces the occupation of the area above the pipeline, which is a difficulty frequently encountered in practical engineering. Disclosure of Invention It is an object of the present invention to solve at least the above problems and to provide at least the advantages to be described later. The invention also aims to provide a nondestructive rapid detection method for the cathodic protection effect of the PCCP pipeline in the HM water supply engineering, which aims to solve the technical problems that the measurement result is seriously distorted and the cathodic protection state of the internal steel cylinder cannot be truly reflected due to the high resistance characteristic of the concrete protection layer of the PCCP pipeline in the traditional pipeline ground potential measurement method. The method is used for carrying out rapid