A comprehensive detection method for non-metal pipelines with large burial depth

Abstract

The application discloses a comprehensive detection method for a nonmetal pipeline with large buried depth, which combines multiple geophysical prospecting methods organically according to model test research, numerical simulation methods, physical characteristics of the pipeline to be detected, and can realize accurate detection of the trend and buried depth of the nonmetal pipeline with large buried depth. The technical problem that the nonmetal pipeline is difficult to be detected by conventional methods due to the deep buried depth and the non-conductivity and non-magnetic conductivity of the pipeline is effectively overcome, and the method has high practical value in pipeline maintenance, reconstruction, new construction and other engineering.

Description

Technical Field

[0001] This invention belongs to the field of pipeline detection, and specifically relates to a comprehensive detection method for deep-buried non-metallic pipelines. Background Technology

[0002] Urban underground pipeline detection is a fundamental task for promoting environmental protection and urban pipeline network renovation, and also an important basis for related design work. With the continuous acceleration of urbanization, the layout of urban pipeline systems is becoming increasingly complex and numerous, and data on pipeline layouts for different purposes and at different times are difficult to share. Therefore, conducting pipeline detection during production activities is particularly necessary. Metallic pipelines are relatively easy to detect due to their electrical and magnetic properties. However, the increasing use of non-metallic pipelines such as PE, PVC, and concrete in municipal construction presents challenges to detection due to their deep burial and lack of electrical and magnetic properties. Furthermore, the large burial depth of most pipelines further increases the complexity of detection work. Therefore, there is an urgent need to explore a new comprehensive detection method for deep-buried non-metallic pipelines to meet production needs. Summary of the Invention

[0003] This invention addresses the challenge of detecting non-metallic pipelines in the field of underground pipeline detection by proposing a comprehensive detection method for deep-buried non-metallic pipelines. This method is applicable to the detection of deep-buried non-metallic pipelines and can overcome the technical difficulties of detecting non-metallic pipelines at great depths and those that are non-conductive and non-magnetic, which make them difficult to detect using conventional methods. It enables precise detection of the burial depth and direction of non-metallic pipelines in the target area.

[0004] To achieve the above-mentioned technical features, the objective of this invention is as follows: A comprehensive detection method for deep-buried non-metallic pipelines, comprising the following steps:

[0005] Step 1, Organizing historical data:

[0006] Collect historical data on pipelines in the area to be detected. For obvious pipeline points that can be investigated in the field, use the direct method of drilling wells; for hidden pipeline points, use geophysical methods to detect them.

[0007] Step 2, On-site inspection:

[0008] Investigate the main media types in the area to be explored and determine the physical properties of the main media. Based on the different media and topographical characteristics of the area, formulate different geophysical methods for exploration.

[0009] Step 3, determine the physical properties of the pipeline to be detected:

[0010] Tests were conducted on parts of the pipeline with known burial locations and depths to be tested, and the electrical and elastic properties of the pipeline material were analyzed.

[0011] Step 4, Research Area Exploration:

[0012] Target detection is carried out based on historical data and the detection environment, combined with different detection principles.

[0013] Step 5, Retesting and Verification:

[0014] After completing the above-mentioned exploration, all survey lines in the study area were re-measured using ground-penetrating radar, and excavation was carried out to verify the results based on the actual situation, thereby further improving the accuracy of the exploration.

[0015] The physical properties of the medium in step two include wave velocity, density, and resistivity.

[0016] Step 4 includes the following steps:

[0017] Step 4.1: When the pipeline point to be measured is known, the surface wave method is used for exploration. A survey line is laid out every 5 to 10 meters along the known part of the non-metallic pipeline. The survey lines are laid out forward in sequence according to the tracking and detection results, with a point spacing of 1 meter and a survey line length of 14 to 31 meters. The dispersion information of the surface wave is extracted from the collected surface wave data, and the velocity information of the underground medium is inferred, thereby determining the burial depth and direction of the target pipeline.

[0018] Step 4.2: When there is an electrical difference between the stratum where the non-metallic pipeline is located and the adjacent stratum or between the target pipeline and the surrounding medium, a high-density electrical resistivity tomography is used to detect the pipeline by combining the previous detection data, detection depth and terrain features. Starting from the known location of the pipeline to be measured, 60 or 120 electrodes are selected with an electrode spacing of 1 to 2 m and are simultaneously deployed along the survey line to form a fixed array to establish an artificial electric field and detect and record the distribution and characteristics of the underground pipeline's conduction current.

[0019] Step 4.3: Based on high-density electrical resistivity tomography (EDT), when the area where the pipeline is located is narrow and has large topographic relief, a seismic source with high frequency, high power, short aftershocks, and good repeatability is selected based on the principle of shallow reflection. A receiving sensor with high sensitivity, low noise, wide bandwidth, and large dynamic range is selected to transmit and receive signals in the corresponding band, complete the re-detection, and then analyze the changes in wave impedance. The direction and burial depth of the pipeline are determined based on the phase, amplitude, frequency, and trend changes in the reflection information.

[0020] When using the surface wave method in step 4.1 for exploration, the ground should be relatively flat or the slope should be monoclinic with little undulation, and the influence of complex terrain such as ditches and ridges and obstacles should be avoided.

[0021] When using the high-density electrical resistivity tomography method in step 4.2 for detection, in order to make full use of the observation data of each arrangement and ensure the lateral and vertical inversion accuracy of the measurement data, the α, α2, β arrangement device is selected to fix the cross-section scanning measurement method, and the measurement points on the cross-section are distributed in an inverted trapezoidal shape.

[0022] In order to ensure the quality of observation and obtain detailed and reliable data, the working status of the instrument must be strictly checked before each operation to ensure that the instrument is working properly. Before each measurement, the automatic grounding resistance of 60 or 120 electrodes must be checked to ensure that the electrodes are well grounded and that the grounding resistance of each electrode is uniform.

[0023] Step 5 includes the following steps:

[0024] Step 5.1: Using the ground-penetrating radar method, establish a wavefield analysis model, conduct detection and verification of all survey lines in the study area, and appropriately extend and densify the survey line length and density to ensure the accuracy of the detection results;

[0025] Step 5.2 requires on-site excavation verification of key areas based on the detection results. Excavation will be carried out layer by layer with dynamic monitoring throughout the process. Within the excavation area, high-density electrical resistivity tomography (EDT) and seismic imaging methods will be used for detection. Outside the excavation area, high-density EDT and micro-motion methods will be used for detection. Anomalies within the next excavation depth will be analyzed in detail, and preliminary analysis of anomalies at deeper levels will be conducted. Once anomalies are found, the owner and construction unit will be notified in a timely manner for handling. Then, the next layer of excavation will proceed, and the above geophysical monitoring process will be repeated until the design depth is reached.

[0026] The specific operation of the ground-penetrating radar method in step 5.1 includes the following steps:

[0027] Ground-penetrating radar (GPR) mainly studies the distribution and characteristics of the detected medium by recording the arrival time t and amplitude of the reflected waves at the interface between different media of the detected object. The wave field analysis model is shown in formula (1):

[0028]

[0029] In the formula, x: refers to the distance between the transmitting antenna and the receiving antenna; h: refers to the depth of the reflecting interface; v: refers to the propagation speed of electromagnetic waves in the underground medium;

[0030] The electromagnetic wave velocity v of the stratum is usually known or can be measured by the wide-angle method. Therefore, by using the profile method to record the electromagnetic wave travel time t, the thickness of the stratum or the burial depth of the target body can be obtained by formula (2). Based on the intensity of the reflected wave, the waveform change and the continuity of the phase axis of the reflected wave, the distribution and orientation of the underground medium or target body can be determined.

[0031]

[0032] The present invention has the following beneficial effects:

[0033] This method is applicable to the detection of non-metallic pipelines buried at great depths. It can overcome the technical difficulties of detecting non-metallic pipelines that are buried at great depths and that are not conductive or magnetic, making them difficult to detect using conventional methods. It enables precise detection of the burial depth and direction of non-metallic pipelines in the target area. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Figure 1 This is a schematic diagram illustrating the working principle of high-density electrical resistivity tomography (EDT).

[0036] Figure 2 This is a diagram illustrating the working principle of the seismic imaging method.

[0037] Figure 3 This is a schematic diagram illustrating the principle of ground-penetrating radar (GPR) detection. Detailed Implementation

[0038] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0039] Example 1:

[0040] like Figure 1-3 As shown, a comprehensive detection method for deep-buried non-metallic pipelines includes the following steps:

[0041] Step 1, Organizing historical data:

[0042] Collect historical data on pipelines in the area to be detected. For obvious pipeline points that can be investigated in the field, use the direct method of drilling wells; for hidden pipeline points, use geophysical methods to detect them.

[0043] Step 2, On-site inspection:

[0044] Investigate the main media types in the area to be explored and determine the physical properties of the main media. Based on the different media and topographical characteristics of the area, formulate different geophysical methods for exploration.

[0045] Step 3, determine the physical properties of the pipeline to be detected:

[0046] Tests were conducted on parts of the pipeline with known burial locations and depths to be tested, and the electrical and elastic properties of the pipeline material were analyzed.

[0047] Step 4, Research Area Exploration:

[0048] Target detection is carried out based on historical data and the detection environment, combined with different detection principles.

[0049] Step 4.1: When the pipeline point to be measured is known, the surface wave method is used for exploration. A survey line is laid out every 5 to 10 meters along the known part of the non-metallic pipeline. The survey lines are laid out forward in sequence according to the tracking and detection results, with a point spacing of 1 meter and a survey line length of 14 to 31 meters. The dispersion information of the surface wave is extracted from the collected surface wave data, and the velocity information of the underground medium is inferred, thereby determining the burial depth and direction of the target pipeline.

[0050] When using the surface wave method in step 4.1 for exploration, the ground should be relatively flat or the slope should be monoclinic with little undulation, and the influence of complex terrain such as ditches and ridges and obstacles should be avoided.

[0051] Step 4.2: When there is an electrical difference between the stratum where the non-metallic pipeline is located and the adjacent stratum or between the target pipeline and the surrounding medium, a high-density electrical resistivity tomography is used to detect the pipeline by combining the previous detection data, detection depth and terrain features. Starting from the known location of the pipeline to be measured, 60 or 120 electrodes are selected with an electrode spacing of 1 to 2 m and are simultaneously deployed along the survey line to form a fixed array to establish an artificial electric field and detect and record the distribution and characteristics of the underground pipeline's conduction current.

[0052] When using the high-density electrical resistivity tomography method in step 4.2 for detection, in order to make full use of the observation data of each arrangement and ensure the lateral and vertical inversion accuracy of the measurement data, the α, α2, β arrangement device is selected to fix the cross-section scanning measurement method, and the measurement points on the cross-section are distributed in an inverted trapezoidal shape.

[0053] In order to ensure the quality of observation and obtain detailed and reliable data, the working status of the instrument must be strictly checked before each operation to ensure that the instrument is working properly. Before each measurement, the automatic grounding resistance of 60 or 120 electrodes must be checked to ensure that the electrodes are well grounded and that the grounding resistance of each electrode is uniform.

[0054] Step 4.3: Based on high-density electrical resistivity tomography (EDT), when the area where the pipeline is located is narrow and has large topographic relief, a seismic source with high frequency, high power, short aftershocks, and good repeatability is selected based on the principle of shallow reflection. A receiving sensor with high sensitivity, low noise, wide bandwidth, and large dynamic range is selected to transmit and receive signals in the corresponding band, complete the re-detection, and then analyze the changes in wave impedance. The direction and burial depth of the pipeline are determined based on the phase, amplitude, frequency, and trend changes in the reflection information.

[0055] Step 5, Retesting and Verification:

[0056] After completing the above-mentioned exploration, all survey lines in the study area were re-measured using ground-penetrating radar, and excavation was carried out to verify the results based on the actual situation, thereby further improving the accuracy of the exploration.

[0057] Step 5.1: Using the ground-penetrating radar method, establish a wavefield analysis model, conduct detection and verification of all survey lines in the study area, and appropriately extend and densify the survey line length and density to ensure the accuracy of the detection results;

[0058] Ground-penetrating radar (GPR) mainly studies the distribution and characteristics of the detected medium by recording the arrival time t and amplitude of the reflected waves at the interface between different media of the detected object. The wave field analysis model is shown in formula (1):

[0059]

[0060] In the formula, x: refers to the distance between the transmitting antenna and the receiving antenna; h: refers to the depth of the reflecting interface; v: refers to the propagation speed of electromagnetic waves in the underground medium;

[0061] The electromagnetic wave velocity v of the stratum is usually known or can be measured by the wide-angle method. Therefore, by using the profile method to record the electromagnetic wave travel time t, the thickness of the stratum or the burial depth of the target body can be obtained by formula (2). Based on the intensity of the reflected wave, the waveform change and the continuity of the phase axis of the reflected wave, the distribution and orientation of the underground medium or target body can be determined.

[0062]

[0063] Step 5.2 requires on-site excavation verification of key areas based on the detection results. Excavation will be carried out layer by layer with dynamic monitoring throughout the process. Within the excavation area, high-density electrical resistivity tomography (EDT) and seismic imaging methods will be used for detection. Outside the excavation area, high-density EDT and micro-motion methods will be used for detection. Anomalies within the next excavation depth will be analyzed in detail, and preliminary analysis of anomalies at deeper levels will be conducted. Once anomalies are found, the owner and construction unit will be notified in a timely manner for handling. Then, the next layer of excavation will proceed, and the above geophysical monitoring process will be repeated until the design depth is reached.

[0064] Furthermore, the physical properties of the medium in step two include wave velocity, density, and resistivity.

Claims

1. A comprehensive detection method for deep-buried non-metallic pipelines, characterized in that, Includes the following steps: Step 1, Organizing historical data: Collect historical data on pipelines in the area to be detected. For obvious pipeline points that can be investigated in the field, use the direct method of drilling wells; for hidden pipeline points, use geophysical methods to detect them. Step 2, On-site inspection: Investigate the main media types in the area to be explored and determine the physical properties of the main media. Based on the different media and topographical characteristics of the area, formulate different geophysical methods for exploration. Step 3, determine the physical properties of the pipeline to be detected: Tests were conducted on parts of the pipeline with known burial locations and depths to be tested, and the electrical and elastic properties of the pipeline material were analyzed. Step 4, Research Area Exploration: Target detection is carried out based on historical data and the detection environment, combined with different detection principles. Step 4.1: When the pipeline point to be measured is known, the surface wave method is used for exploration. A survey line is laid out every 5 to 10 meters along the known part of the non-metallic pipeline. The survey lines are laid out forward in sequence according to the tracking and detection results, with a point spacing of 1 meter and a survey line length of 14 to 31 meters. The dispersion information of the surface wave is extracted from the collected surface wave data, and the velocity information of the underground medium is inferred, thereby determining the burial depth and direction of the target pipeline. Step 4.2: When there is an electrical difference between the stratum where the non-metallic pipeline is located and the adjacent stratum or between the target pipeline and the surrounding medium, a high-density electrical resistivity tomography is used to detect the pipeline by combining the previous detection data, detection depth and terrain features. Starting from the known location of the pipeline to be measured, 60 or 120 electrodes are selected with an electrode spacing of 1 to 2 m and are simultaneously deployed along the survey line to form a fixed array to establish an artificial electric field and detect and record the distribution and characteristics of the underground pipeline's conduction current. Step 4.3: Based on the high-density electrical resistivity tomography (EDT) detection, when the area where the pipeline is located is narrow and has large topographic relief, a seismic source with high frequency, high power, short aftershocks, and good repeatability is selected based on the principle of shallow reflection. A receiving sensor with high sensitivity, low noise, wide bandwidth, and large dynamic range is selected to transmit and receive signals in the corresponding band, complete the re-detection, and then analyze the changes in wave impedance. The direction and burial depth of the pipeline are determined based on the phase, amplitude, frequency, and trend changes in the reflection information. Step 5, Retesting and Verification: After completing the above-mentioned exploration, all survey lines in the study area were re-measured using ground-penetrating radar, and excavation was carried out to verify the results based on the actual situation, thereby further improving the accuracy of the exploration.

2. The comprehensive detection method for deep-buried non-metallic pipelines according to claim 1, characterized in that: The physical properties of the medium in step two include wave velocity, density, and resistivity.

3. The comprehensive detection method for deep-buried non-metallic pipelines according to claim 1, characterized in that: When using the surface wave method in step 4.1 for exploration, the ground should be relatively flat or the slope should be monoclinic with little undulation, and the influence of complex terrain such as ditches and ridges and obstacles should be avoided.

4. The comprehensive detection method for deep-buried non-metallic pipelines according to claim 1, characterized in that: When using the high-density electrical resistivity tomography method in step 4.2 for detection, in order to make full use of the observation data of each arrangement and ensure the lateral and vertical inversion accuracy of the measurement data, the α, α2, β arrangement device is selected to fix the cross-section scanning measurement method, and the measurement points on the cross-section are distributed in an inverted trapezoidal shape. In order to ensure the quality of observation and obtain detailed and reliable data, the working status of the instrument must be strictly checked before each operation to ensure that the instrument is working properly. Before each measurement, the automatic grounding resistance of 60 or 120 electrodes must be checked to ensure that the electrodes are well grounded and that the grounding resistance of each electrode is uniform.

5. The comprehensive detection method for deep-buried non-metallic pipelines according to claim 1, characterized in that: Step 5 includes the following steps: Step 5.1: Using the ground-penetrating radar method, establish a wavefield analysis model, conduct detection and verification of all survey lines in the study area, and appropriately extend and densify the survey line length and density to ensure the accuracy of the detection results; Step 5.2 requires on-site excavation verification of key areas based on the detection results. Excavation will be carried out layer by layer with dynamic monitoring throughout the process. Within the excavation area, high-density electrical resistivity tomography (EDT) and seismic imaging methods will be used for detection. Outside the excavation area, high-density EDT and micro-motion methods will be used for detection. Anomalies within the next excavation depth will be analyzed in detail, and preliminary analysis of anomalies at deeper levels will be conducted. Once anomalies are found, the owner and construction unit will be notified in a timely manner for handling. Then, the next layer of excavation will proceed, and the above geophysical monitoring process will be repeated until the design depth is reached.

6. The comprehensive detection method for deep-buried non-metallic pipelines according to claim 5, characterized in that: The specific operation of the ground-penetrating radar method in step 5.1 includes the following steps: Ground-penetrating radar mainly studies the distribution and characteristics of the detected medium by recording the arrival time t and amplitude of the reflected waves at the interface between different media of the detected object. The wave field analysis model is shown in formula (1): （1） In the formula, This refers to the distance between the transmitting antenna and the receiving antenna. : refers to the depth of the reflective interface; : Refers to the speed at which electromagnetic waves propagate in underground media; electromagnetic wave velocity of the strata The travel time of electromagnetic waves is usually known or can be measured using the wide-angle method; therefore, the profiling method is used to record the travel time of electromagnetic waves. The thickness of the stratum or the burial depth of the target body can be obtained by using formula (2); the distribution and orientation of the underground medium or target body can be judged based on the intensity, waveform change and continuity of the phase axis of the reflected wave. （2）。

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