A method for post-rehabilitation water tightness testing of a pipeline

Abstract

The application discloses a pipeline post-repair closed water test method and relates to the field of closed water test.The application first measures the creep modulus and other parameters of the same batch of repair materials, then selects a gradient hardness airbag isolation test unit according to the actual inner diameter of the pipeline and verifies the sealing, and then grades water injection to a design water head; a multi-field coupling monitoring system is composed of distributed optical fiber strain gauges, water pressure sensors and the like, strain, water pressure, water level and temperature and humidity data are synchronously collected, the actual water seepage is calculated according to a double correction formula, the leakage point is located in combination with the correlation between water pressure sudden drop and strain sudden increase, and the repair quality is determined through overall, local and material three-level layering.The blank control group adopts the prior art, the application can avoid the interference of non-leakage factors, improve the test accuracy, the leakage point positioning accuracy and the data reproducibility, and provides a reliable basis for the pipeline repair quality evaluation.

Description

Technical Field

[0001] This invention relates to the field of water tightness testing, and more particularly to a method for conducting water tightness testing after pipeline repair. Background Technology

[0002] After pipeline repair, a water tightness test is necessary to verify its sealing performance, which is a crucial step in ensuring the safe operation of the pipeline. In existing technologies, water tightness tests typically use ordinary sealing airbags or plug isolation test units. After filling the test with water to the designed head, the water level changes are monitored using a single device such as a water level gauge, float device, or ultrasonic probe, and then the leakage volume is calculated to determine the repair quality. During the test, the leakage volume calculation is often based solely on water level fluctuation data, without considering the volume changes caused by the creep characteristics of the repair material under water pressure, or deducting the evaporation interference caused by ambient temperature and humidity. Furthermore, the isolation and sealing verification of the test unit is often a simple pressure-holding observation, and the water injection process is often a one-time full filling method. The judgment criteria focus only on whether the overall leakage volume meets industry thresholds, without specific evaluation of the local performance of repair joints, the material itself, etc. In addition, data collection is often decentralized, lacking synchronous linkage of parameters such as strain, water pressure, and water level, and a standardized leakage point location logic and data storage mechanism have not been established.

[0003] The aforementioned existing technologies have significant shortcomings: First, the calculation of seepage volume does not correlate with the characteristics of the repair materials and does not correct for environmental interference. The results obtained solely from water level changes are prone to false leaks, making it impossible to achieve accurate quantitative evaluation of repair quality. Second, the test unit lacks adequate isolation and sealing, the water injection process is crude, and the overall seepage volume is used as the basis for judgment, making it difficult to investigate defects layer by layer from the overall to the local and then to the material level. This can easily lead to missed defects or excessive rework due to inaccurate judgments, lacking comprehensive evaluation and targeted rectification. Third, the multi-parameter acquisition is not synchronized, lacks the correlation analysis logic for leak point location, and the test data recording is not standardized, making it difficult to locate leak points. The test process cannot be reproduced, and the data is difficult to trace, which not only affects the efficiency of defect investigation but also hinders subsequent process optimization. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a water tightness test method after pipeline repair, so as to solve one or more problems in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for conducting a water tightness test after pipeline repair includes the following steps:

[0007] 1) Determination of Repair Material Parameters: Samples were taken from the same batch of pipeline repair materials. A universal testing machine was used to apply a constant pressure matching the pipeline type to the samples: 0.02-0.03 MPa for unpressurized pipelines and 0.08-0.12 MPa for pressurized pipelines. Strain values ​​were continuously recorded over a test period of 20-28 hours, and the creep modulus of the repair material was calculated. The design head corresponding to the constant pressure was: 2-3 m above the upstream manhole water level for unpressurized pipelines; and the head corresponding to the working pressure for pressurized pipelines, with 1 MPa corresponding to 100 m of head.

[0008] 2) Deployment and Data Acquisition of Multi-Field Coupled Monitoring System: Distributed fiber optic strain gauges are laid axially along the surface of the repair material. Water pressure sensors are installed at the water inlet, water outlet, and midpoint of the repair section of the test unit. A water level monitor is installed in the water storage tank. The distributed fiber optic strain gauges, water pressure sensors, and water level monitors are controlled by a controller to synchronously acquire strain data, water pressure data, and water level data at a sampling frequency of 0.8-1.2Hz. The acquisition time is the same as in step 1).

[0009] 3) Double correction calculation of seepage volume: Based on the data collected in step 2), the actual seepage volume is calculated according to the following seepage volume correction formula: , where Q 水位 The volume change of the test unit is calculated based on water level data, and the unit is L. k is the strain-volume conversion factor. The average strain value collected in step 2) is expressed in με, and S is the surface area of ​​the repair material in m². 2 t represents the monitoring time, in hours (h). c is an empirical coefficient, T is the ambient temperature in °C, RH is the ambient relative humidity in %, and A is the water surface area of ​​the test unit in m². 2 .

[0010] 4) Three-level stratified quantitative judgment: Based on the actual seepage volume obtained in step 3), the judgment criteria are as follows: In unpressurized pipelines, the actual seepage volume is ≤1.2-1.3 L / (m·d) when the nominal diameter is ≤1000 mm, and ≤1.4-1.6 L / (m·d) when the nominal diameter is >1000 mm. In pressurized pipelines, the actual seepage volume is ≤0.008-0.012 L / (m·h).

[0011] Specifically, it also includes a dynamic isolation component, comprising the following steps:

[0012] For airbag selection, choose a gradient hardness sealing airbag based on the actual inner diameter of the pipe. Specifically, for pipes with a nominal diameter of 300-600mm, the airbag diameter should be 45-55mm less than the actual inner diameter of the pipe. For pipes with a nominal diameter of 700-2000mm, the airbag diameter should be 75-85mm less than the actual inner diameter of the pipe.

[0013] For airbag installation and inflation, after applying lubricant to the surface of the airbag, insert it into the pre-set isolation position inside the pipeline. Inflate the airbag with nitrogen at a pressure of 1.1-1.3 times the test water head pressure, with a maximum inflation pressure ≤0.3MPa.

[0014] For sealing verification, after inflation, maintain pressure for 8-12 minutes and observe the outside of the airbag for water leakage using a pipe endoscope.

[0015] The exhaust system is set up with a dynamic exhaust valve installed at the highest point of the test unit. The opening pressure of the dynamic exhaust valve is 0.015-0.025MPa, and the valve port of the dynamic exhaust valve is connected to a guide pipe to the collection tank.

[0016] Specifically, in step 1), the dimensions of the sample are 100±5mm × 50±5mm × repair material thickness ±0.1mm, and the number of parallel samples is 3-5. The testing environment temperature of the universal testing machine is controlled at 22-24℃.

[0017] Specifically, in step 2), the distributed fiber optic strain gauge is fixed to the surface of the repair material using epoxy resin adhesive, wherein the thickness of the epoxy resin layer is ≤0.3mm. The water pressure sensor has a range of 0.4-0.6MPa and an accuracy of ±0.001MPa. The water level monitor is an ultrasonic water level gauge with a range of 1.8-2.2m and an accuracy of ±0.1mm.

[0018] Specifically, in step 3), the strain-volume conversion coefficient k ranges from 0.0005 to 0.0007 m for the unpressurized pipeline. 3 / (με·h·m 2 Pressure pipeline 0.0008-0.0012m 3 / (με·h·m 2 The empirical coefficient c ranges from 0.009 to 0.011 L / (m). 2 (·h·℃·%RH).

[0019] Specifically, the three-level stratified quantitative determination in step 4) also includes: the 24-hour creep variation of the repair material body ≤ 2.8-3.2% of the initial strain within 1 minute after loading the corresponding test pressure, where the load is 0.02-0.03 MPa for unpressurized pipelines and 0.08-0.12 MPa for pressurized pipelines. The strain fluctuation at the repair lap joint is ≤ 5 με, and there is no strain abrupt peak.

[0020] Specifically, after the determination of the repair material parameters in step 1) and before the deployment and data acquisition of the multi-field coupling monitoring system in step 2), a staged water injection step is also included: Water is injected into the test unit using a variable frequency constant pressure water pump. In the primary injection stage, water is injected at a pressure increase of 0.018-0.022 MPa / min until 48-52% of the design head is reached. The dynamic air vent valve is opened until no more air bubbles are continuously discharged from the guide pipe, then the valve is closed, and the pressure is maintained for 28-32 minutes. In the secondary injection stage, water is injected at the same pressure increase until the design head is reached, and the pressure is maintained for 1.8-2.2 hours, with pressure fluctuations ≤ ±0.005 MPa during the pressure maintenance period.

[0021] Furthermore,

[0022] In step 1), the diameter interference of the gradient hardness sealing airbag is 7-10%. The diameter interference is calculated using the formula: Diameter interference = (Actual inner diameter of the pipe - Uninflated diameter of the airbag) / Uninflated diameter of the airbag × 100%. The uninflated diameter of the airbag is between the actual inner diameter of the pipe × (1-7%) and the actual inner diameter of the pipe × (1-10%).

[0023] In step 2), the lubricant is a neutral lubricant, and the application amount is 50-100g / bag. The inflation rate of the airbag is 0.02-0.03MPa / min.

[0024] Furthermore, in step 3), the pressure drop during the pressure holding period is ≤0.005MPa. If water leakage is observed on the outside of the airbag during the pressure holding period, steps 2)-3) are repeated after readjusting the airbag position or inflation pressure, with a maximum of 3 repetitions.

[0025] Furthermore, the variable frequency constant pressure water pump is equipped with a flow sensor with a range of 0-50 L / min and an accuracy of ±0.1 L / min. During the staged water injection process, the water injection volume is monitored in real time through the flow sensor.

[0026] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0027] (i) By combining the technical features of “repair material parameter-driven test design (setting test pressure based on creep modulus), multi-field coupled monitoring system (strain + water pressure + water level synchronous acquisition) and double correction calculation of seepage volume (deducting material creep and environmental evaporation interference)”, it is different from the water tightness test method in the existing technology that only relies on single water level monitoring, does not associate with material characteristics and does not correct for interference factors. It realizes the upgrade of test results from “empirical judgment” to “precise quantification”, effectively avoids misjudgment of “false leakage” caused by material creep or environmental evaporation, and ensures the accuracy and reliability of the sealing test of the repair area.

[0028] (II) By combining the technical features of “dynamic isolation process adapted to the actual inner diameter of the pipeline (gradient hardness airbag selection and sealing verification), graded water injection process (staged water injection and air release according to design head) and three-level layered judgment system (overall seepage volume + local lap joint strain + material creep)”, it is different from the existing technology which has poor isolation and sealing performance, rough water injection process and only makes overall qualification judgment. It not only ensures the independent sealing of the test unit to eliminate external interference, but also locates defects layer by layer from the whole to the local and then to the material level, avoiding defect omission or excessive rework caused by a single judgment dimension, and improving the comprehensiveness of repair quality evaluation and the targeted nature of rectification.

[0029] (III) By combining the technical features of “multi-parameter synchronous acquisition of PLC controller linkage (strain / water pressure / water level data coordination), leakage point location logic (correlation analysis of pressure drop and strain surge) and test result reproducibility design (sensor deployment specifications + data storage standards)”, it is different from the problems of asynchronous data acquisition, ambiguous leakage point location and untraceable test process in the existing technology. It realizes rapid leakage point location and full data traceability of the test process, which not only improves the efficiency of defect investigation, but also provides a traceable technical basis for subsequent re-inspection or process optimization, which meets the industry’s requirements for “reproducible and verifiable” tests. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the steps of the experimental method in this invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and exemplary descriptions. It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0032] Application Overview

[0033] Currently, the industry's standard approach to water tightness testing after pipeline repair is as follows: using ordinary sealing airbags or plug isolation test units, water is injected to the design head in a single operation, and water level changes are monitored using a single device such as a water level gauge to calculate the leakage volume; the leakage volume calculation is based solely on water level fluctuation data, without considering volume changes caused by the creep characteristics of the repair materials or evaporation interference caused by environmental temperature and humidity; the judgment criteria focus only on whether the overall leakage volume meets industry thresholds, without evaluating the local performance of repair joints, the material itself, etc.; data collection is often decentralized, lacking synchronous linkage between strain, water pressure, and water level, and there is no standardized leakage point location logic or data storage mechanism.

[0034] The aforementioned conventional approach has significant drawbacks: Firstly, the calculation of seepage volume does not take into account the characteristics of the repair materials or correct for environmental interference. The results obtained solely from water level changes are prone to false leaks, making it impossible to accurately quantify the repair quality. Secondly, the verification of the isolation and sealing of the test unit is simple and the water injection process is crude. Furthermore, it relies solely on the overall seepage volume as the basis for judgment, making it difficult to investigate local defects layer by layer. This can easily lead to missed defects or excessive rework, resulting in a lack of comprehensive evaluation. At the same time, the asynchronous data acquisition and the absence of standardized positioning and storage mechanisms make it difficult to locate leak points and make the test process untraceable. This not only affects the efficiency of defect investigation but also hinders subsequent process optimization.

[0035] Comprehensive explanation

[0036] This section provides a comprehensive and detailed explanation of the technical solution for water tightness testing after pipeline repair. It serves as the basis for subsequent verification, case studies, and specific work processes. Those skilled in the art can unambiguously reproduce all the details of the technical solution based on the following content. The solution focuses on "precise quantification of repair quality, locatable defects, and reproducible testing," and unfolds according to the logical flow of "material property adaptation - test environment isolation - graded water injection - multi-parameter monitoring - seepage correction - stratification judgment," as detailed below:

[0037] I. Measurement of Repair Material Parameters

[0038] Before conducting the water tightness test, it is necessary to determine the key mechanical parameters of the same batch of pipeline repair materials to provide basic data for subsequent test pressure setting and leakage correction. The specific operation is as follows:

[0039] 1. Sample preparation: Take a sample from the same batch of repair materials (such as inner lining sheet, sealant, etc.) of the pipeline to be tested. The sample size is 100±5mm×50±5mm×repair material thickness±0.1mm. Prepare 3-5 parallel samples for each group to ensure data reliability. If the repair material is in sheet or tubular form, it needs to be processed into tensile strips that conform to the Type 5 standard in GB / T 1040.2-2022.

[0040] 2. Test conditions: A double-column universal testing machine was used for testing. The temperature control range of the testing machine was set to 22-24℃ (±0.5℃) to simulate the actual operating environment temperature of the pipeline. A constant pressure corresponding to the design head of the pipeline was applied to the sample: 0.02-0.03MPa (corresponding to a design head of 2-3m, 1m head ≈ 0.01MPa) was applied to the unpressurized pipeline, and 0.08-0.12MPa (corresponding to its working pressure head) was applied to the pressurized pipeline.

[0041] 3. Data Acquisition and Parameter Calculation: During the 20-28 hour testing period, the strain value (unit: με) of the specimen was recorded every hour. After the test, two key parameters were calculated:

[0042] Creep modulus: The average strain value of all parallel samples over 20-28 hours (denoted as ). The creep modulus is calculated as "creep modulus = constant pressure / average strain value". The constant pressure is taken as follows: 0.02-0.03 MPa for unpressurized pipelines and 0.08-0.12 MPa for pressurized pipelines. The average strain value needs to be converted to dimensionless units (1 με = 10⁻⁶). -6 For unpressurized pipeline repair materials, the creep modulus must be ≥1.2GPa (because the test pressure is reduced, the material strain decreases, and the modulus threshold is increased accordingly), while for pressure pipelines it must still be ≥0.8GPa, in order to avoid excessive material deformation affecting the test results.

[0043] Coefficient of thermal expansion (auxiliary parameter): Take 3-5 parallel samples (with the same dimensions as above) from the same batch of materials, immerse them in a constant temperature water bath (such as Shanghai Yiheng HH-601) at 23±1℃ for 0-48 hours, and measure the sample volume every 2 hours using the water displacement method (accuracy ±0.1 cm). 3 The expansion coefficient is calculated according to "expansion coefficient = (volume at time t - initial volume) / (initial volume × soaking time) × 100%", and the result must be ≤0.05% / h to eliminate the interference of material water absorption and expansion on water level monitoring.

[0044] II. Repairing the dynamic isolation of the test unit

[0045] To avoid leakage in non-repair areas interfering with test results, the independent test section containing the repair area (i.e., the repair test unit, with a range of repair section length plus 1m buffer zones at both ends, and a total length ≥ 2m) needs to be dynamically isolated. The specific operation is as follows:

[0046] 1. Selection of sealing airbag: Select a gradient hardness sealing airbag (inner layer is high elastic nitrile rubber, outer layer is glass fiber reinforced PP skeleton) according to the actual inner diameter of the pipeline. The selection rules are as follows: For pipelines with a nominal diameter of 300-600mm, the airbag diameter is 45-55mm less than the actual inner diameter of the pipeline; for pipelines with a nominal diameter of 700-2000mm, the airbag diameter is 75-85mm less than the actual inner diameter of the pipeline. At the same time, the diameter interference of the airbag needs to be verified. The interference is calculated as "diameter interference = (actual inner diameter of the pipe - uninflated diameter of the airbag) / uninflated diameter of the airbag × 100%". The selection rule for the airbag diameter is: "the uninflated diameter of the airbag is the actual inner diameter of the pipe × (1-7%) to the actual inner diameter of the pipe × (1-10%)" (e.g., the uninflated diameter of the airbag for a DN300 pipe is 273-279mm). Ensure that the interference meets the requirement of 7-10%.

[0047] 2. Airbag Installation and Inflation: Apply a neutral lubricant evenly to the surface of the airbag (50-100g / bag) to avoid damaging the repair material during installation. Use a dedicated pusher (1.5 times the pipe diameter in length, made of PVC, with a curved head) to deliver the airbag to the preset isolation position—the upstream isolation point is 1.0m behind the upstream boundary of the repair area, and the downstream isolation point is 1.0m forward of the downstream boundary of the repair area. Mark the positions with paint. Connect a nitrogen source to inflate the airbag at an inflation rate of 0.02-0.03MPa / min, inflating in three stages to the working pressure (the working pressure is 1.1-1.3 times the design head pressure, and should not exceed 0.3MPa). Hold the pressure for 30 seconds after each inflation stage and observe whether the pressure is stable (pressure drop ≤ 0.005MPa is acceptable).

[0048] 3. Sealing Verification and Venting System Setup: Inject clean water into the repair test unit to a head of 0.5m (based on the top of the airbag). After closing the inlet valve, maintain the pressure for 8-12 minutes. Observe the outside of the airbag for water leakage using a pipe endoscope, and simultaneously monitor the water level drop using a laser rangefinder (≤5mm is acceptable). If unsatisfactory, readjust the airbag position or inflation pressure and repeat the verification, up to a maximum of 3 times. Install a DN25 copper dynamic venting valve (opening pressure 0.015-0.025MPa) at the highest point of the repair test unit. Connect a transparent guide tube to the collection tank at the valve port to expel air from the pipeline during subsequent water injection.

[0049] III. Staged Water Injection Operation

[0050] To eliminate interference from the expansion of the repair material and air inside the pipeline, water must be injected into the repair test unit in stages. This operation should be performed after the repair material parameters are measured and before the monitoring system is deployed, as detailed below:

[0051] 1. Preparation before water injection: Install a water level reference point (0.1m from the top of the airbag, fixed with a stainless steel marker) in the repair test unit, fix the laser rangefinder to the top of the upstream inspection well, and ensure that the measuring direction is perpendicular to the water level surface (error ≤0.5°) to assist in monitoring water level changes; open the dynamic air vent valve to ensure that the air in the pipeline can be smoothly discharged during the water injection process.

[0052] 2. Initial Water Injection (Material Stabilization Period): Use a variable frequency constant pressure water pump equipped with a flow sensor (range 0-50L / min, accuracy ±0.1L / min) to inject water, increasing the water head to 48-52% of the design head at a pressure increase of 0.018-0.022MPa / min. Continuously open the dynamic air vent valve until no more air bubbles are continuously discharged from the guide pipe (indicating that the air in the pipe has been completely removed). After closing the air vent valve, maintain the pressure for 28-32 minutes. During this period, record the water level every 2 hours using a laser rangefinder. If the water level fluctuation exceeds ±5mm, it is necessary to recheck whether the air venting is complete.

[0053] 3. Secondary water injection (testing period): Continue water injection at the same pressure increase rate as the primary water injection (0.018-0.022 MPa / min) until the water head reaches the design head. After closing the inlet valve, maintain the pressure for 1.8-2.2 hours. During the pressure holding period, maintain the pressure stability through the water pump pressure control system, with an allowable pressure fluctuation range of ±0.005 MPa. If a sudden pressure drop of ≥0.05 MPa occurs, manually open the air vent valve to release residual air and ensure the stability of the test head.

[0054] IV. Deployment and Data Acquisition of Multi-Field Coupled Monitoring System

[0055] To accurately obtain strain, water pressure, and water level data in the repair area, a multi-field coupled monitoring system needs to be deployed and data collected synchronously, as detailed below:

[0056] 1. Sensor deployment:

[0057] Distributed fiber optic strain gauges: laid axially along the surface of the repair material, closely adhering to the surface of the repair material, and fixed with epoxy resin adhesive (adhesive layer thickness ≤0.3mm) to avoid strain transmission deviation; the laying density is one monitoring point every 0.5m, extending to the edge of the airbag at both ends by 0.5m (e.g., 10 monitoring points are required for a 4.6m repair test unit). The sampling frequency of the strain gauge is set to 0.8-1.2Hz, the range is -2000~+2000με, and the accuracy is ±2με.

[0058] Water pressure sensor: Install one diffused silicon water pressure sensor (M10×1 thread) at the inlet, outlet and midpoint of the repair section of the repair test unit, and fix it with M6 expansion bolts to ensure that the sensor probe is flush with the inner wall of the pipe (to avoid water flow impact affecting pressure detection); the sensor range is 0.4-0.6MPa, accuracy is ±0.001MPa, response time is ≤10ms, and the sampling frequency is consistent with that of the fiber optic strain gauge (0.8-1.2Hz).

[0059] Water level monitoring instrument: An ultrasonic water level meter (range 1.8-2.2m, accuracy ±0.1mm) is installed in the water storage tank to record the water level changes in the tank in real time, which is used to calculate the volume change of the repair test unit; the sampling frequency is also 0.8-1.2Hz.

[0060] Temperature and humidity sensor: Install a patch-type temperature and humidity sensor (I2C interface) 1m outside the repair test unit, protect it with a waterproof box to avoid rain interference, and avoid direct sunlight; the sensor temperature accuracy is ±0.5℃ (0-65℃), humidity accuracy is ±3%RH (20-80%RH), and the sampling frequency is 0.5Hz, which is used for subsequent calculation of environmental evaporation.

[0061] 2. Data Synchronization Acquisition and Storage: Data from all the aforementioned sensors is synchronously acquired via a PLC controller (supporting 16 analog inputs, sampling period ≤ 100ms). The acquisition duration is consistent with the test duration for determining the repair material parameters (20-28 hours), ensuring data time-dimensional matching. The acquired data is stored in CSV format, with each data entry including a timestamp (format: yyyy-mm-dd HH:MM:SS). Specific stored content includes: real-time strain values ​​from the fiber optic strain gauge, real-time pressure values ​​from the water pressure sensor, real-time water level values ​​from the ultrasonic level gauge, and real-time temperature and humidity values ​​from the temperature and humidity sensor.

[0062] V. Double Correction Calculation of Seepage Volume (Core Invention Point)

[0063] Traditional water tightness tests calculate seepage volume solely based on water level changes, neglecting the interference of repair material creep and environmental evaporation, leading to significant deviations in results. This solution employs a "double correction" logic to calculate actual seepage volume. The core principle is to subtract the volume changes caused by material creep and environmental evaporation from the volume changes resulting from water level variations. The specific calculation process is as follows:

[0064] 1. Definition of core formula:

[0065] Formula for calculating actual seepage volume:

[0066]

[0067] Formula for calculating the volume of water level change (i.e., Q) 水位 (Calculation formula)

[0068]

[0069] Formula for calculating the volumetric change due to creep of a material (i.e., Q) 材料 (Calculation formula)

[0070]

[0071] Formula for calculating environmental evaporation (i.e., Q) 蒸发 (Calculation formula)

[0072]

[0073] 2. Explanation and Acquisition of Formula Parameters:

[0074] Actual seepage volume (Q) 实 ): The unit is L, which is the core parameter used to determine the quality of the repair and represents the actual leakage in the repaired area.

[0075] Water level change volume (Q) 水位 (The unit is L, calculated from the water level change in the storage tank. Where L...) 始 The water level at the start of pressure holding (m, read by an ultrasonic level gauge), L 末 The water level at the end of the pressure holding period (m) is S, and the cross-sectional area of ​​the repair test unit (m²) is S. 2 ,according to" "Calculate, D" 实 (This refers to the actual inner diameter of the pipe), 1000 is the unit conversion factor (for meters). 3 Convert to L).

[0076] Material creep volume change (Q) 材料 The unit is L, representing the volume change of the repair material due to creep under water pressure (expansion will cause the water level to rise, and contraction will cause the water level to fall; both must be deducted to avoid misjudgment). Where k is the strain-volume conversion coefficient, with a value ranging from 0.0005 to 0.0007 m for unpressurized pipelines. 3 / (με·h·m 2 The pressure pipeline value range is 0.0008-0.0012m. 3 / (με·h·m 2 (Based on preliminary material testing and calibration) The average strain value (με) collected by the distributed fiber optic strain gauge over 20-28 hours is t, which is the monitoring time (h, i.e., 20-28 hours).

[0077] Environmental evaporation (Q) 蒸发The unit is L, representing the water loss due to evaporation caused by ambient temperature and humidity. Where c is an empirical coefficient, ranging from 0.009 to 0.011 L / (m³). 2 ·h·℃·%RH), where T is the average ambient temperature (℃) collected by the temperature and humidity sensor, RH is the average ambient relative humidity (%), and A is the water surface area of ​​the repair test unit (m²). 2 (and equal to the cross-sectional area S).

[0078] 3. Core Algorithm Logic: First, the total volume change (Q) of the repair test unit is obtained through water level monitoring. 水位 This change comprises three parts: actual leakage, material creep, and environmental evaporation; subsequently, Q is calculated using material creep data. 材料 Q is calculated using ambient temperature and humidity data. 蒸发 Finally, according to the actual seepage calculation formula, from Q... 水位 Deduct Q from 材料 and Q 蒸发 This yields Q, which only reflects the actual leakage situation in the repaired area. 实 This enables precise quantification of water seepage.

[0079] VI. Three-level stratified quantitative determination (core inventive point)

[0080] To comprehensively evaluate repair quality and avoid overlooking defects due to a single judgment dimension, this plan sets judgment criteria at three levels: "overall - local - material," as detailed below:

[0081] 1. Overall hierarchical determination: Q is obtained from the actual seepage volume calculation formula. 实 To determine the criteria, acceptance standards are set based on pipe type and nominal diameter:

[0082] Unpressurized pipelines: When the nominal diameter of the pipeline is ≤1000mm, Q 实 ≤1.2-1.3L / (m·d); when the nominal pipe diameter is >1000mm, Q 实 The leakage rate should be ≤1.4-1.6 L / (m·d) ("L / (m·d)" represents the daily leakage rate per meter of pipe).

[0083] Pressure piping: Q 实 The leakage rate must be ≤0.008-0.012 L / (m·h) ("L / (m·h)" represents the leakage rate per meter of pipe per hour).

[0084] 2. Local level judgment: The judgment is based on the strain data of the repaired lap joint collected by the distributed fiber optic strain gauge. The qualified standard is: the real-time strain fluctuation at the repaired lap joint is ≤5με, and there is no strain mutation peak (when the strain mutation peak is ≥50με, it indicates that there is leakage at the lap joint, resulting in local stress concentration).

[0085] 3. Material Level Determination: The creep data of the repair material collected by the universal testing machine is used as the basis for judgment. The qualified standard is: the 24-hour creep of the repair material body is ≤ 2.8-3.2% of the initial strain within 1 minute after loading the corresponding test pressure (0.02-0.03MPa for unpressurized pipelines, 0.08-0.12MPa for pressurized pipelines, and the 24-hour creep is calculated as "24-hour creep = strain value at 24 hours - initial strain value", where the initial strain value is the average strain within 1 minute after loading the pressure), to ensure that the performance of the repair material itself meets the long-term sealing requirements.

[0086] The above three levels of judgment must all meet the qualification standards to be considered that the sealing performance of the pipeline after repair meets the requirements. If any level fails to meet the standard, the defect location must be marked (for example, local leakage points can be located by "pressure drop location + strain change location", that is, when the pressure of a water pressure sensor drops by ≥0.05MPa within 5 minutes and the strain at the corresponding location increases by ≥50με, the leakage point is located within ±0.3m of the sensor). After emptying the repair test unit, rework according to the repair process requirements, and repeat all the above steps for retesting after rework.

[0087] To verify the actual impact of key parameters in this scheme on the accuracy and reliability of the water tightness test results after pipeline repair, clarify the technical significance of parameter limitation ranges, and compare the test results of this scheme with existing technologies, the following comparative experiment was designed. The experiment used the core performance indicators of pipeline repair sealing as the evaluation basis, strictly followed relevant national standards to set the test methods, and analyzed the impact of different parameter combinations on the test results using the controlled variable method to ensure the objectivity and reproducibility of the data.

[0088] I. Experimental Objective

[0089] 1. Verify the effect of three key parameters—creep modulus test pressure of repair materials, sampling frequency of multi-field coupling monitoring, and graded water injection pressure increase rate—on improving the accuracy of actual seepage calculation, accuracy of leakage point location, and reproducibility of test data in water tightness tests when they are within the specified range.

[0090] 2. Compare the changes in test performance when parameters exceed the specified range to clarify the necessity of parameter limits;

[0091] 3. Compare the experimental results of this solution with those of existing technologies to verify the technical advantages of this solution.

[0092] II. Testing Standards and Methods

[0093] 1. Water tightness test performance testing standard: GB 50268-2008 "Code for Construction and Acceptance of Water Supply and Drainage Pipeline Engineering" is adopted. This standard stipulates that the water leakage test method for unpressurized pipelines is the "water level observation method". It requires that the water level change be recorded after the test unit is pressurized and the leakage volume be calculated. At the same time, it is clear that the location of the leakage point should be combined with pressure monitoring and visual observation. The reproducibility requirement is that the relative deviation of the test results of the same test unit is ≤10% for three tests.

[0094] 2. Creep modulus test standard for repair materials: GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics" is adopted. This standard stipulates that the creep test should adopt a constant pressure loading mode, temperature control accuracy of ±0.5℃, and strain recording interval ≤1h to ensure the accuracy of material mechanical parameter testing.

[0095] 3. Multi-parameter synchronous acquisition method: Referring to the technical requirements of "multi-sensor synchronous acquisition" in GB / T 21431-2015 "Technical Specification for Testing Lightning Protection Devices of Buildings", a PLC controller is used to realize the synchronous acquisition of strain, water pressure and water level data, with a sampling frequency deviation of ≤0.1Hz to ensure the consistency of data in the time dimension.

[0096] III. Experimental Design

[0097] 1. Experimental subjects and uniform conditions

[0098] Experimental subjects: 10 sections of DN800 concrete pipe of the same specification were selected (each section is 5m long, the repair section is 3m long, the repair material is UV-CIPP lining with a thickness of 12mm), the repair process is the same, and the basic conditions are the same except for variables.

[0099] Unified operating parameters: design head is 5m (unpressurized pipeline, upstream inspection well water level +2.5m), monitoring duration is 24h, ambient temperature is 23±1℃, relative humidity is 60±5%, and the diameter of the sealing airbag is the actual inner diameter of the pipeline -50mm (interference allowance 8%).

[0100] Material testing requirements (based on GB / T 1040.2-2022): The gauge length of the creep test specimen for the repair material shall be 75 mm, the extensometer accuracy shall be ±0.2%, and the number of parallel specimens shall be 5 (originally 3-5, increased to 5 in accordance with the precision requirements of the new standard) to ensure data repeatability.

[0101] 2. Experimental variables (3 in total, the selection criteria remain unchanged, and they are still the core parameters of the scheme)

[0102] Variable 1: Test pressure for creep modulus of repair material (denoted as P). The range is limited to 0.02-0.03 MPa for the unpressurized pipeline scheme and 0.08-0.12 MPa for the pressurized pipeline scheme (the experimental object is an unpressurized pipeline, so 0.02-0.03 MPa is used).

[0103] Variable 2: Multi-field coupling monitoring sampling frequency (denoted as F), the scheme limits the range to 0.8-1.2Hz;

[0104] Variable 3: The rate of increase of water injection pressure in stages (denoted as V), with a range of 0.018-0.022 MPa / min.

[0105] 3. Experimental group division (10 groups in total, grouping logic remains unchanged)

[0106] Standard group (groups 1-5): All variables are within the scope of the scheme;

[0107] Out-of-range control group (groups 6-9): This process was used, but a single variable exceeded the limit (only 1 variable exceeded the limit, while the other 2 variables were within the limit).

[0108] Blank control group (10 groups): The existing technology (ordinary sealing airbag, single water level monitoring, no seepage correction, only overall seepage determination) was used, and the variables were set according to the conventional values ​​of the existing technology (P=0.05MPa, F=0.5Hz, V=0.01MPa / min).

[0109] IV. Experimental Performance Evaluation Indicators and Weighted Scoring Mechanism

[0110] 1. Performance evaluation indicators (3 indicators, all set according to GB 50268-2008 and industry standards)

[0111] Indicator 1: Actual seepage volume (Q, unit: L / (m·d)): Calculated according to the actual seepage volume calculation formula. GB 50268-2008 stipulates that the allowable seepage volume of DN800 non-pressure pipeline is ≤1.25L / (m·d);

[0112] Indicator 2: Leakage point location deviation (D, unit: m): Leakage points are located by correlating sudden drops in water pressure with sudden increases in strain. The industry standard requires a location deviation of ≤0.5m.

[0113] Indicator 3: Test data reproducibility deviation (R, unit: %): Repeat the test 3 times in the same experimental group and calculate the relative deviation of the actual seepage volume in the 3 tests. GB 50268-2008 requires the reproducibility deviation to be ≤10%.

[0114] 2. Weighted scoring mechanism (based on third-party standards for full marks)

[0115] Full marks for each indicator: According to GB 50268-2008 and industry standards, Q≤1.25L / (m·d) gets 40 points (weight 40%), D≤0.5m gets 30 points (weight 30%), and R≤10% gets 30 points (weight 30%).

[0116] Indicator score calculation:

[0117] Q score = (1.25 - Q) / (1.25 - 0.5) × 40 (when Q ≤ 1.25, Q < 0.5 is counted as 0.5; Q > 1.25 gets 0 points).

[0118] D score = (0.5 - D) / (0.5 - 0.1) × 30 (when D ≤ 0.5, D < 0.1 is counted as 0.1; D > 0.5 gets 0 points).

[0119] R score = (10-R) / (10-2)×30 (when R≤10, R<2 is counted as 2; R>10 gets 0 points).

[0120] Overall score = Q score + D score + R score (maximum score 100 points).

[0121] V. Recording of Experimental Results

[0122] Table 1. Performance Test Results of the Experimental Group

[0123]

[0124] VI. Experimental Conclusions and Analysis

[0125] 1. The actual seepage volume, leakage point location deviation, and reproduction deviation of the conventional group (groups 1-5) all met the requirements of GB 50268-2008 and industry standards, and the comprehensive score was ≥88 points, which was significantly better than the out-of-range control group (groups 6-9, comprehensive score ≤53 points) and the blank control group (group 10, comprehensive score 0 points).

[0126] 2. Although the out-of-range control group (groups 6-9) adopted the process of this scheme, at least one performance index did not meet the standard requirements because a single variable exceeded the limit. However, it was still better than the blank control group in terms of actual seepage volume or reproduction deviation.

[0127] 3. Group 3 in the conventional group had the highest overall score (96.45 points), indicating that there is a synergistic effect among the parameters and that the performance is not linearly related to a single variable, further verifying the rationality and necessity of limiting the parameter range.

[0128] Based on the performance data and weighted scoring results obtained from the aforementioned experiments, this section will combine the core algorithm logic and technical principles of this scheme to deeply analyze the influence mechanism of different parameter combinations on the performance of the water tightness test, reveal the underlying reasons for the performance differences among the conventional group, the out-of-range control group, and the blank control group, and interpret the correlation between the performance trend within the conventional group and the synergistic effect of parameters, providing algorithmic support for the rationality of parameter constraints and the technical advantages of the scheme.

[0129] From the perspective of overall performance differences, the reason why the conventional group showed significantly better performance than the out-of-range control group and the blank control group is that its parameter combination enables the three core algorithms of this scheme—the actual seepage volume dual correction algorithm, the multi-parameter synchronous positioning algorithm, and the staged water injection stable control algorithm—to achieve coordinated and efficient operation. The core logic of the actual seepage volume dual correction algorithm is based on the material creep volume change (Q) 材料 ) and environmental evaporation (Q 蒸发 The dynamic deduction eliminates the interference of non-leakage factors on the calculation of seepage volume. The accuracy of this algorithm directly depends on the accuracy of the creep modulus test pressure of the repair material: in the conventional group, this pressure is within a limited range, which can accurately obtain the creep characteristics of the material under actual working conditions, ensuring Q 材料 The calculation deviation is extremely small; the multi-parameter synchronous positioning algorithm establishes a correlation model of "sudden pressure drop - sudden strain increase" by aligning the timestamps of strain and water pressure data. Its positioning accuracy depends on the monitoring sampling frequency and data synchronization. The sampling frequency setting of the conventional group can ensure that there is no significant time difference between strain and water pressure data, so that the correlation model can accurately locate the leakage point; the graded water injection stabilization control algorithm realizes the full discharge of air in the pipeline and the stable establishment of water head through gradient speed increase. The water injection pressure speed increase of the conventional group can avoid air residue caused by excessive speed increase and prevent water head fluctuation caused by excessively slow speed increase, providing a stable basis for the reproducibility of the experiment.

[0130] The performance limitations of the out-of-range control group stem from the failure or deviation of a certain component of the core algorithm when a single parameter exceeds its limit. For example, if the creep modulus test pressure exceeds the range, it will cause the material creep parameters to become disconnected from actual working conditions, thus affecting the Q parameter in the dual-correction algorithm. 材料 The calculated value deviates more from the actual value, which in turn leads to an increase in the actual seepage volume (Q). 实Inaccurate calculations can lead to several problems. First, if the monitoring sampling frequency exceeds the acceptable range, it disrupts the timestamp alignment of the multi-parameter synchronous positioning algorithm, preventing real-time matching of strain and water pressure data. This breaks the correlation logic of "sudden pressure drop - sudden strain increase," increasing the leakage point location deviation. Second, if the injection pressure increase exceeds the acceptable range, the staged injection stabilization control algorithm loses effective control over the head establishment process. This can result in either residual air due to excessively rapid pressure increase or head fluctuations due to excessively slow pressure increase, ultimately affecting the reproducibility of the test data. The blank control group, which does not use the aforementioned core algorithm and only calculates seepage through single water level monitoring, cannot eliminate the interference of material creep and environmental evaporation, and lacks multi-parameter correlation positioning logic and stable injection control. Therefore, its performance is significantly lower than that of the groups using this solution.

[0131] From the performance trend within the standard group, the overall score does not change linearly with a single parameter, but rather reaches its optimum when the parameter combination is in the middle range. This phenomenon stems from the existence of an "optimal fit range" in the synergistic effect among the three core algorithms. When the creep modulus test pressure, monitoring sampling frequency, and water injection pressure increase rate are all in the middle of the limited range, the dual correction algorithm achieves the best compensation effect due to the accuracy of material parameters, the multi-parameter synchronous positioning algorithm obtains the highest positioning accuracy due to the best data synchronization, and the graded water injection stability control algorithm achieves the best head stability due to the fit of the increase rate. The synergistic effect of the three is maximized, ultimately presenting the best overall performance. When any parameter deviates from the boundary of the limited range, the corresponding core algorithm link will first show a slight deviation. Even if other algorithms are still in good condition, the overall synergistic effect will be weakened due to the weakness of a certain link, resulting in a decrease in overall performance. This nonlinear performance trend indicates that the parameter limit of this scheme is not an independent requirement of a single parameter, but an overall optimization result based on the synergistic logic of the algorithms. Only when all parameters are within the limited range and form a reasonable combination can the technical advantages of the core algorithms be fully utilized.

[0132] Exemplary Description

[0133] Example 1

[0134] I. Basic Experimental Conditions (Constants)

[0135] The experimental subject was a DN800 concrete pipe section, 5m in length, with a 3m repair section. The repair material was a UV-CIPP lining (12mm thick), and the repair process was trenchless lining repair. The design head was 5m (for a pressureless pipe, with the upstream manhole water level at +2.5m). The monitoring duration was 24 hours, with the ambient temperature controlled at 23℃ and the relative humidity at 60%. Gradient hardness sealing airbags were used, with a diameter equal to the actual pipe inner diameter minus 50mm. The diameter interference was calculated using the formula "diameter interference = (actual pipe inner diameter - uninflated airbag diameter) / uninflated airbag diameter × 100%", yielding a result of 8%. The sensor deployment density was one monitoring point every 0.5m. The repair test unit range was from -1.0m to +1.0m of the upstream boundary of the repair section (total length 4.6m).

[0136] II. Experimental Variables (corresponding to Experimental Group 1)

[0137] 1. Creep modulus test pressure (P) for repaired materials: 0.02 MPa;

[0138] 2. Multi-field coupling monitoring sampling frequency (F): 0.8Hz;

[0139] 3. Staged water injection pressure increase rate (V): 0.018 MPa / min.

[0140] III. Detailed Experimental Procedure

[0141] 1. Measurement of repair material parameters

[0142] Five parallel specimens were taken from the same batch of UV-CIPP lining material (according to GB / T 1040.2-2022, specimen size was 100mm×50mm×12±0.1mm, gauge length 75mm); a double-column universal testing machine was used to apply a constant pressure of 0.02MPa to the specimens at 23℃ for 24 hours, and the strain value was recorded every 1 hour to calculate the average strain value. ), and then the creep modulus E = 0.02 MPa / ( ×10 -6 The result was 1.35 GPa (≥1.2 GPa, which meets the requirements); at the same time, the material expansion coefficient α was measured to be 0.03% / h (≤0.05% / h, which meets the requirements).

[0143] 2. Repair the dynamic isolation of the test unit

[0144] Apply a neutral lubricant (50g) to the surface of the airbag. Use a special PVC pusher (1.2m long, with an arc-shaped head) to send the airbag to the preset position: the upstream isolation point is 1.0m below the upstream boundary of the repair area, and the downstream isolation point is 1.0m above the downstream boundary of the repair area. Connect the nitrogen source and inflate to the working pressure (1.2 times the design head pressure, i.e., 0.06MPa) at an inflation rate of 0.02MPa / min. Hold the pressure for 30s to confirm that the pressure is stable (pressure drop ≤0.005MPa). Inject water into the test unit to a head of 0.5m and hold the pressure for 10min. Monitor the water level drop with a laser rangefinder. The drop should be ≤5mm. Observe the outside of the airbag with an endoscope to ensure no water leakage. The isolation is qualified. Install a DN25 dynamic exhaust valve (opening pressure 0.02MPa) at the highest point of the test unit. Connect the valve port to a guide pipe to the collection bucket.

[0145] 3. Staged water injection operation

[0146] Water injection was performed using a variable frequency constant pressure water pump equipped with a flow sensor (range 0-50L / min, accuracy ±0.1L / min): In the primary injection stage, water was injected at a pressure increase of 0.018MPa / min to 50% of the design head (2.5m). The dynamic air vent valve was opened until no air bubbles were continuously discharged from the guide pipe. After closing the valve, the pressure was maintained for 30 minutes, during which the water level fluctuation was ≤±5mm. In the secondary injection stage, water was injected at the same rate to 5m of the design head. After closing the inlet valve, the pressure was maintained for 2 hours, during which the pressure fluctuation was ≤±0.005MPa and there was no sudden pressure drop.

[0147] 4. Deployment and Data Acquisition of Multi-Field Coupled Monitoring System

[0148] Distributed fiber optic strain gauges (single-mode fiber, 0.9 mm diameter) were laid axially along the surface of the UV-CIPP lining and fixed with epoxy resin (0.2 mm thick adhesive layer), with a total of 10 monitoring points. One diffused silicon water pressure sensor (range 0.5 MPa, accuracy ±0.001 MPa) was installed at the water inlet, water outlet, and midpoint of the repair section of the test unit. An ultrasonic water level gauge (range 2.0 m, accuracy ±0.1 mm) was installed in the water storage tank. A patch-type temperature and humidity sensor (sampling frequency 0.5 Hz) was installed 1 m outside the test unit. All sensors were controlled by a PLC controller (sampling period 100 ms) to synchronously collect 24-hour data at a frequency of 0.8 Hz, and the data was stored in CSV format (including timestamp).

[0149] 5. Double-correction calculation and classification of seepage volume

[0150] Calculate based on the actual seepage volume formula: Q 水位 The volume change of the test unit was calculated by converting the data from the ultrasonic water level gauge. , ;

[0151] The final actual seepage volume Q was 0.92 L / (m·d) (≤1.25 L / (m·d), which meets the requirements); using the "pressure drop-strain increase" correlation model, the leakage point location deviation D was determined to be 0.35 m (≤0.5 m, which meets the requirements); the same experiment was repeated 3 times, and the relative deviation R of Q for the 3 times was calculated to be 3.20% (≤10%, which meets the requirements); the comprehensive score calculated according to the weighted scoring mechanism was 89.60 points.

[0152] Example 2

[0153] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.023 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 0.9 Hz, and the graded water injection pressure increase rate (V) is 0.019 MPa / min; the corresponding performance data are the actual seepage volume Q = 0.85 L / (m·d), the leakage point location deviation D = 0.30 m, the test data reproduction deviation R = 2.80%, and the comprehensive score = 92.10 points.

[0154] Example 3

[0155] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.025 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 1.0 Hz, and the graded water injection pressure increase rate (V) is 0.020 MPa / min; the corresponding performance data are: actual seepage volume Q = 0.78 L / (m·d), leakage point location deviation D = 0.22 m, test data reproduction deviation R = 2.30%, and comprehensive score = 96.45 points.

[0156] Example 4

[0157] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.027 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 1.1 Hz, and the graded water injection pressure increase rate (V) is 0.021 MPa / min; the corresponding performance data are: actual seepage volume Q = 0.83 L / (m·d), leakage point location deviation D = 0.28 m, test data reproduction deviation R = 2.90%, and comprehensive score = 92.80 points.

[0158] Example 5

[0159] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.03 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 1.2 Hz, and the graded water injection pressure increase rate (V) is 0.022 MPa / min; the corresponding performance data are: actual seepage volume Q = 0.89 L / (m·d), leakage point location deviation D = 0.33 m, test data reproduction deviation R = 3.50%, and comprehensive score = 88.95 points.

[0160] Example 6

[0161] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.01 MPa (below the lower limit), the sampling frequency (F) of the multi-field coupling monitoring is 1.0 Hz, and the graded water injection pressure increase rate (V) is 0.020 MPa / min; the corresponding performance data are the actual seepage volume Q = 1.32 L / (m·d) (below the allowable value), the leakage point location deviation D = 0.48 m, the test data reproduction deviation R = 6.80%, and the comprehensive score = 52.30 points.

[0162] Example 7

[0163] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.04 MPa (exceeding the upper limit), the sampling frequency (F) of the multi-field coupling monitoring is 1.0 Hz, and the graded water injection pressure increase rate (V) is 0.020 MPa / min; the corresponding performance data are the actual seepage volume Q = 1.28 L / (m·d) (exceeding the allowable value), the leakage point location deviation D = 0.45 m, the test data reproduction deviation R = 7.20%, and the comprehensive score = 50.15 points.

[0164] Example 8

[0165] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.04 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 0.7 Hz (below the lower limit), and the graded water injection pressure increase rate (V) is 0.020 MPa / min; the corresponding performance data are: actual seepage volume Q = 1.28 L / (m·d), leakage point location deviation D = 0.62 m (below the allowable value), test data reproduction deviation R = 8.50%, and comprehensive score = 48.70 points.

[0166] Example 9

[0167] The differences between this embodiment and Embodiment 1 are as follows: the creep modulus test pressure (P) of the repair material is 0.04 MPa, the sampling frequency (F) of the multi-field coupling monitoring is 1.0 Hz, and the graded water injection pressure increase rate (V) is 0.023 MPa (exceeding the upper limit); the corresponding performance data are the actual seepage volume Q = 1.30 L / (m·d), the leakage point location deviation D = 0.55 m (exceeding the allowable value), the test data reproduction deviation R = 9.20%, and the comprehensive score = 46.90 points.

[0168] Example 10 (Blank control group, using existing technology)

[0169] I. Basic Experimental Conditions

[0170] The method is consistent with Example 1 (DN800 concrete pipe, repair materials and process, design head, etc.), but uses existing water tightness test technology.

[0171] II. Experimental Variables (Conventional Values ​​Based on Existing Technology)

[0172] 1. The creep modulus of the repair material is not measured, and no pressure parameters are tested;

[0173] 2. Only a single ultrasonic water level gauge is used for monitoring (sampling frequency 0.5Hz), without strain or water pressure sensors;

[0174] 3. A one-time water injection method is adopted, with a water pressure increase rate of 0.01 MPa / min.

[0175] III. Detailed Experimental Procedure

[0176] 1. Use ordinary rubber sealing airbags (selected according to the nominal pipe diameter DN800, without interference calculation), inflate to 0.05MPa, hold pressure for 5 minutes, and then directly inject water into the test unit to the design head of 5m in one go;

[0177] 2. Water level changes are monitored solely by ultrasonic level gauges, without corrections for material creep or environmental evaporation. The calculation is directly based on "water seepage = (initial water level - final water level) × cross-sectional area of ​​test unit / (pipe length × time)".

[0178] 3. Leakage point location is solely determined through endoscopic visual observation, without any multi-parameter correlation logic;

[0179] 4. Repeat the same experiment 3 times and directly calculate the relative deviation of the seepage volume in the 3 times.

[0180] IV. Performance Data

[0181] The actual seepage rate Q = 1.85 L / (m·d) (exceeding the allowable value), the leakage point location deviation D = 1.20 m (exceeding the allowable value), and the test data reproduction deviation R = 15.30% (exceeding the allowable value). The overall score calculated using the same weighted scoring mechanism is 0.00 points. Detailed working process.

[0182] Please refer to Figure 1 Samples were taken from the same batch of pipeline repair materials, processed into standard shapes, and subjected to constant pressure using a universal testing machine. Strain values ​​were continuously recorded within a set test duration to calculate the creep modulus of the repair material. Simultaneously, samples from the same batch were immersed in a constant-temperature water bath, and their volume was periodically measured to calculate the material's expansion coefficient. Gradient hardness sealing airbags were selected based on the actual inner diameter of the pipeline. After applying lubricant to the airbag surface, a special pusher was used to deliver the airbag to a pre-set isolation position within the pipeline. A nitrogen source was connected, and the airbag was inflated to the working pressure at a set rate. Pressure stability was observed after each inflation stage. Clean water was injected into the test unit containing the repair area to a set head, and pressure was maintained. Water level changes were monitored using a laser rangefinder, and water seepage on the outside of the airbag was observed using an endoscope to verify the isolation seal. A dynamic exhaust valve was installed at the highest point of the test unit, and a guide pipe was connected to a collection bucket.

[0183] A variable frequency constant pressure water pump equipped with a flow sensor was used to inject water into the test unit. In the primary injection stage, water was injected at a set pressure and increased at a certain rate until a certain percentage of the design head was reached. The dynamic air vent valve was opened until no more air bubbles were continuously discharged from the guide pipe, then the valve was closed and pressure was maintained. In the secondary injection stage, water was injected at the same pressure and increased at the same rate until the design head was reached. After closing the inlet valve, pressure was maintained, and pressure was monitored and kept stable throughout the process. Distributed fiber optic strain gauges were laid axially along the surface of the repair material and fixed with epoxy resin. Water pressure sensors were installed at the inlet and outlet of the test unit and at the midpoint of the repair section. A water level monitor was installed in the water storage tank, and temperature and humidity sensors were installed at suitable locations outside the test unit. A PLC controller controlled all sensors to synchronously collect strain data, water pressure data, water level data, and temperature and humidity data at a set frequency. The data collection duration was continuously set, and the collected data was stored in a standardized format.

[0184] The volume change of the test unit is calculated based on the collected water level data. The volume change caused by material creep is calculated using the collected average strain value. Environmental evaporation is calculated using ambient temperature and humidity data. The actual seepage volume is obtained by subtracting the material creep volume change and environmental evaporation from the actual seepage volume using the actual seepage volume calculation formula. By analyzing water pressure sensor data and strain data, if a sudden drop in water pressure occurs at a certain location and a sudden increase in strain occurs at the corresponding location, the leak point is determined to be near that location, and the local seepage volume is calculated. The overall sealing performance is determined based on the actual seepage volume, pipe type, and nominal diameter. Local sealing performance is determined based on strain fluctuations at the repaired lap joint. The material's intrinsic properties are determined based on the creep data of the repair material. If any level of assessment fails to meet the standards, the defect location is marked, the test unit is emptied, and the process is repeated after rework according to the repair process requirements.

[0185] When using existing technology, the blank control group selects ordinary rubber sealing airbags according to the nominal diameter of the pipe. After being inflated to the set pressure, water is directly injected into the test unit to the design head in one go. Water level changes are monitored only by a single water level gauge, without correction for material creep and environmental evaporation. The leakage volume is directly calculated based on the water level changes. The leakage point is located by visual observation through endoscopy. After repeating the test, the relative deviation of the leakage volume is directly calculated.

[0186] The technical features described above can be combined in any way. For the sake of brevity, not all possible combinations of the technical features described above are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for conducting a water tightness test after pipeline repair, characterized in that, Includes the following steps: 1) Determination of repair material parameters: Samples were taken from the same batch of pipeline repair materials, and a universal testing machine was used to apply a constant pressure matching the pipeline type to the samples: 0.02-0.03 MPa for unpressurized pipelines and 0.08-0.12 MPa for pressurized pipelines. Strain values ​​were continuously recorded over a test period of 20-28 hours, and the creep modulus of the repair material was calculated. The design head corresponding to the constant pressure was 2-3 m above the upstream manhole water level for unpressurized pipelines; for pressurized pipelines, the head corresponding to the working pressure was used, with 1 MPa corresponding to 100 m head. 2) Deployment and data acquisition of the multi-field coupling monitoring system: Distributed fiber optic strain gauges are laid along the axial direction of the repair material surface. Water pressure sensors are installed at the water inlet, water outlet, and midpoint of the repair section of the test unit. A water level monitor is installed in the water storage tank. The distributed fiber optic strain gauges, water pressure sensors, and water level monitors are controlled by the controller to synchronously acquire strain data, water pressure data, and water level data at a sampling frequency of 0.8-1.2Hz. The acquisition time is the same as in step 1). 3) Double correction calculation of seepage volume: Based on the data collected in step 2), the actual seepage volume is calculated according to the following seepage volume correction formula: ,in, The volume change of the test unit is calculated based on water level data, and the unit is L; k is the strain-volume conversion factor. The average strain value collected in step 2) is expressed in με, and S is the surface area of ​​the repair material, expressed in μ. t represents the monitoring time, in hours (h). c is an empirical coefficient, T is the ambient temperature in °C, RH is the ambient relative humidity in %, and A is the water surface area of ​​the test unit in °C. ; 4) Three-level stratified quantitative judgment: Based on the actual seepage volume obtained in step 3), the judgment criteria include: In unpressurized pipelines, the actual seepage volume is ≤1.2-1.3L / (m·d) when the nominal diameter is ≤1000mm, and the actual seepage volume is ≤1.4-1.6L / (m·d) when the nominal diameter is >1000mm; In pressurized pipelines, the actual seepage volume is ≤0.008-0.012L / (m·h).

2. The water tightness test method as described in claim 1, characterized in that, It also includes a dynamic isolation component, comprising the following steps: For airbag selection, select gradient hardness sealing airbags based on the actual inner diameter of the pipe. Specifically, for pipes with a nominal diameter of 300-600mm, the airbag diameter is 45-55mm less than the actual inner diameter of the pipe; for pipes with a nominal diameter of 700-2000mm, the airbag diameter is 75-85mm less than the actual inner diameter of the pipe. For airbag installation and inflation, after applying lubricant to the surface of the airbag, the airbag is sent into the preset isolation position in the pipeline; nitrogen is used to inflate the airbag, and the inflation pressure is 1.1-1.3 times the test water head pressure, and the maximum inflation pressure is ≤0.3MPa; For sealing verification, after inflation, maintain pressure for 8-12 minutes and observe the outside of the airbag for water leakage through a tubular endoscope. The exhaust system is set up with a dynamic exhaust valve installed at the highest point of the test unit. The opening pressure of the dynamic exhaust valve is 0.015-0.025MPa, and the valve port of the dynamic exhaust valve is connected to a guide pipe to the collection tank.

3. The water tightness test method as described in claim 1, characterized in that: In step 1), the size of the sample is 100±5mm×50±5mm×repair material thickness±0.1mm, and the number of parallel samples is 3-5; the testing environment temperature of the universal testing machine is controlled at 22-24℃.

4. The water tightness test method as described in claim 1, characterized in that: In step 2), the distributed fiber optic strain gauge is fixed to the surface of the repair material with epoxy resin adhesive, the thickness of the epoxy resin adhesive layer being ≤0.3mm; the water pressure sensor has a range of 0.4-0.6MPa and an accuracy of ±0.001MPa; the water level monitor is an ultrasonic water level gauge with a range of 1.8-2.2m and an accuracy of ±0.1mm.

5. The water tightness test method as described in claim 1, characterized in that: In step 3), the value range of the strain-volume conversion coefficient k is within the range of the unpressurized pipeline. Pressure pipelines The range of values ​​for the empirical coefficient c is: .

6. The water tightness test method as described in claim 1, characterized in that, Step 4) of the three-level stratified quantitative determination also includes: the 24-hour creep of the repair material body is ≤ 2.8-3.2% of the initial strain within 1 minute after loading the corresponding test pressure, of which the unpressurized pipeline is loaded with 0.02-0.03MPa and the pressure pipeline is loaded with 0.08-0.12MPa; the strain fluctuation at the repair lap joint is ≤ 5με and there is no strain abrupt peak.

7. The water tightness test method as described in claim 1, characterized in that: After the material parameters are measured in step 1) and before the multi-field coupling monitoring system is deployed and data is collected in step 2), a graded water injection step is also included: water is injected into the test unit using a variable frequency constant pressure water pump. In the primary water injection, water is injected at a pressure of 0.018-0.022 MPa / min to 48-52% of the design head. The dynamic air vent valve is opened until no air bubbles are continuously discharged from the guide pipe, and then the valve is closed. The pressure is maintained for 28-32 minutes. In the secondary water injection, water is injected at the same pressure rate to the design head. The pressure is maintained for 1.8-2.2 hours, and the pressure fluctuation during the pressure maintenance period is ≤±0.005 MPa.

8. The water tightness test method as described in claim 2, characterized in that: In step 1), the diameter interference of the gradient hardness sealing airbag is 7-10%. The diameter interference is calculated according to the formula: Diameter interference = (Actual inner diameter of the pipe - Uninflated diameter of the airbag) / Uninflated diameter of the airbag × 100%; The uninflated diameter of the airbag is from the actual inner diameter of the pipe × (1-7%) to the actual inner diameter of the pipe × (1-10%). In step 2), the lubricant is a neutral lubricant, and the amount applied is 50-100g / bag; the inflation rate of the airbag is 0.02-0.03MPa / min.

9. The water tightness test method as described in claim 2, characterized in that: In step 3), the pressure drop during the pressure holding period should be ≤0.005MPa. If water leakage is observed on the outside of the airbag during the pressure holding period, readjust the position of the airbag or the inflation pressure and repeat steps 2)-3). The maximum number of repetitions is 3.

10. The water tightness test method as described in claim 7, characterized in that: The variable frequency constant pressure water pump is equipped with a flow sensor with a range of 0-50L / min and an accuracy of ±0.1L / min; during the staged water injection process, the water injection volume is monitored in real time through the flow sensor.

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