A buried PE pipeline depth detection method

Abstract

The application discloses a buried PE pipeline depth detection method, which comprises the following steps: determining the basic direction of the pipeline; arranging a plurality of horizontal plane measuring lines according to the basic direction, and arranging a plane measuring point on each plane measuring line; determining the plane positioning line of the pipeline according to the signal value obtained by the signal receiving device at the plane measuring point; arranging a vertical point according to the plane positioning line of the pipeline, arranging a depth measuring line downwardly and perpendicularly to the ground at the vertical point, arranging a depth measuring point on the depth measuring line, and determining the depth position of the pipeline according to the signal value obtained by the signal receiving device at the depth measuring point. The detection method directly detects the depth position of the buried gas PE pipeline, meets more test environments, and effectively improves the test accuracy; the detection method can provide more accurate test results for actual engineering, thereby effectively reducing the safety risk during pipeline network reconstruction.

Description

Technical Field

[0001] This invention relates to the field of gas pipeline detection technology, specifically to a method for deep detection of buried PE pipelines. Background Technology

[0002] If the gas pipeline information system is incomplete, it may lead to natural gas leaks, explosions, or even casualties. Therefore, accurate positioning of buried gas PE pipelines is particularly important for ensuring the safety of urban construction.

[0003] Because PE pipes are non-conductive, non-magnetic, and essentially insulated, conventional detection methods cannot accurately locate them. Currently, there are many technologies and methods for accurately locating gas PE pipes, such as ground-penetrating radar (which has significant depth limitations, requires highly skilled personnel, and yields inaccurate results) and electromagnetic induction (which is completely impossible to test without a tracer), but all of these methods have significant disadvantages. Active sound source methods are widely used for PE pipe location and detection.

[0004] In recent years, with the development of technology, the method of locating and detecting PE pipelines using active acoustic sources has become increasingly mature. However, this method can currently only achieve accurate positioning of the pipeline in a plane; depth detection is still in its early stages. Currently, depth positioning mainly employs time difference methods, multi-point / matrix fitting methods, and calibration empirical value methods. All of these methods are indirect or simulation-based testing methods, suitable for perfectly homogeneous ideal interfaces. In actual testing, they are greatly limited by the testing scenario and have relatively low accuracy.

[0005] The time-difference method and the multi-point / matrix fitting method primarily test the relationship between time, distance, and wave velocity at different points. Since the active source method uses low frequencies, the time difference between different measurement points is on the order of microseconds. The time deviation caused by medium inhomogeneity is much larger than the time difference between propagation distances, making the test accuracy highly susceptible to environmental factors and resulting in extremely low accuracy. The calibration empirical method involves testing the intensity at different points at different depths within a medium and then fitting the results. The intensity obtained from subsequent tests is then compared to estimate the depth. However, it's difficult to maintain a consistent testing environment, leading to relatively low accuracy. Furthermore, extensive calibration is required for each testing environment, making the overall process quite complex.

[0006] For example, Chinese invention patent application (publication number: CN116224340A) describes a method for calculating the location of non-metallic gas pipelines. This method involves applying a selectable frequency acoustic vibration signal to induce oscillating waves in the natural gas within the pipeline, which then propagate directionally along the pipeline to a distant location. This method assumes that the propagation speed of the medium in the overlying layer above the pipeline is consistent at different measuring points. However, in actual testing, the medium above the pipeline consists of multiple layers, leading to errors of several orders of magnitude in the test results.

[0007] For example, Chinese invention patent application (publication number: CN113759358A) describes a method for detecting buried pipelines. Based on the obtained horizontal coordinates of the pipeline underground, the burial depth of the pipeline is measured by radar directly above it. This method obtains the depth using ground-penetrating radar; however, the radar's testing depth is limited, and it cannot overcome the influence of multiple layers of media above the pipeline.

[0008] In summary, these methods may only be applicable to environmental testing of pure soil media. However, the actual areas with greater safety hazards are buried gas pipelines in municipal or residential areas, which contain a variety of media such as concrete, brick, sand, asphalt, miscellaneous fill, and soil. The presence of these multiple media will greatly reduce the accuracy of the test. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art by providing a method for depth detection of buried PE pipelines.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for detecting the depth of buried PE pipes includes the following steps:

[0012] Determine the basic route of the pipeline;

[0013] Several horizontal planar survey lines are arranged according to the basic direction. Planar survey points are set on each of the planar survey lines. A signal receiving device is connected to the planar survey point. The planar positioning line of the pipeline is determined according to the signal value obtained by the signal receiving device at the planar survey point.

[0014] Vertical points are set according to the planar positioning line of the pipeline, and a safety distance L is provided between the vertical points and the planar positioning line;

[0015] A depth survey line is laid vertically downwards from the ground at the vertical point. Multiple depth survey points are arranged on the depth survey line. The depth survey points are connected to a signal receiving device. The depth position of the pipeline is determined based on the signal value obtained by the signal receiving device at the depth survey point.

[0016] This detection method directly detects the depth of buried gas PE pipelines, meeting the needs of more testing environments and effectively improving testing accuracy. It can provide more accurate test results for actual projects, thereby effectively reducing safety risks during pipeline renovation.

[0017] This detection method transforms horizontal detection into vertical detection, shifting the test surface to a section perpendicular to the medium. This places the measuring point in a homogeneous soil environment beyond a certain depth, resulting in more ideal testing results and higher accuracy. The method first determines the basic pipeline direction. After determining the pipeline's basic direction, it accurately identifies the horizontal positioning line using horizontal measuring points. Then, it sets vertical points based on the pipeline's horizontal positioning line. This process improves the accuracy and effectiveness of vertical point detection.

[0018] Furthermore, the basic direction of the pipeline is determined by the buried vent valve, or by making circular points at any location on the ground to determine the basic direction of the pipeline; a signal transmitting device is installed on the ground corresponding to the pipeline vent valve.

[0019] Furthermore, each of the aforementioned planar survey lines is arranged perpendicular to the basic direction of the pipeline, and multiple planar survey points are arranged at intervals along each of the aforementioned planar survey lines. The location of the planar survey point corresponding to the maximum signal value at the multiple planar survey points on the planar survey line determines the planar position directly above the pipeline. Based on the multiple planar positions directly above the pipeline determined by the multiple planar survey lines, the planar positioning line of the pipeline can be determined.

[0020] Furthermore, each of the aforementioned planar measurement lines is sequentially denoted as a1, a2, a3, ..., aN, where N is a positive integer. The maximum value of the signal at multiple planar measurement points on each of the aforementioned planar measurement lines is obtained and denoted as Maxa1, Maxa2, Maxa3, ..., MaxaN, respectively. The positions of the planar measurement points corresponding to these maximum signal values ​​are fitted by a linear regression equation to determine the planar positioning line of the pipeline.

[0021] In other words, for each planar survey line, multiple measuring points are selected for testing. Multiple corresponding signal values ​​are obtained from these measuring points along the same planar survey line. The location of the measuring point corresponding to the maximum value is then used to determine the planar positioning line of the pipeline. This multi-point testing method reduces errors and improves accuracy. Furthermore, the smaller the spacing between the multiple measuring points along the same planar survey line, the higher the positioning accuracy.

[0022] Furthermore, the arrangement of multiple plane measuring points along each of the aforementioned plane measuring lines involves first arranging several measuring points at equal intervals with a large spacing D1, obtaining the maximum signal value among these points at this large spacing, then rearranging several measuring points at equal intervals with a small spacing d1, using the measuring point corresponding to the maximum signal value as the center, and obtaining the maximum signal value among these rearranged measuring points. The plane position directly above the pipeline is determined by the position of the plane measuring point corresponding to the maximum signal value. The small spacing d1 should be less than the pipeline diameter or less than a set plane position positioning limit. This set plane position positioning limit can be the plane position positioning limit specified in the current standard "Technical Specification for Fine Detection of Underground Pipelines," or it can be a plane position positioning limit preset by the construction party.

[0023] Furthermore, a metal rod is inserted vertically downwards from the vertical point on the ground or inserted through a hole to form the depth measurement line. The metal rod has a built-in signal receiving sensor and is marked with depth, allowing direct reading of the depth position of the signal receiving sensor.

[0024] Furthermore, multiple depth measuring points are arranged at intervals along each depth measuring line. The depth position of the pipeline is obtained based on the depth identifier of the depth measuring point corresponding to the maximum signal value among the multiple depth measuring points on each depth measuring line. The accurate depth value of the pipeline is determined based on the multiple depth positions of the pipeline determined by the multiple depth measuring lines.

[0025] Furthermore, the vertical points are all laid out perpendicular to the planar positioning lines, and the depth measuring lines pass through the vertical points and are arranged parallel to the planar positioning lines. Each depth measuring line is sequentially denoted as b1, b2, b3, ..., bN, where N is a positive integer. The maximum value of the signal at multiple depth measuring points on each depth measuring line is obtained and denoted as Maxb1, Maxb2, Maxb3, ..., MaxbN. The position of the planar measuring point corresponding to the maximum value of these signal values ​​is fitted by a linear regression equation to determine the depth value of the pipeline. Fitting the pipeline depth value in this way can eliminate the testing error caused by geological unevenness. The more measuring lines arranged along the pipeline extension direction, the more accurate the pipeline depth positioning.

[0026] The arrangement of multiple depth measuring points along each depth measuring line involves first arranging several measuring points at equal intervals of a large spacing D2, obtaining the maximum signal value among these points, and then rearranging several measuring points at equal intervals of a small spacing d2, centered on the measuring point corresponding to the maximum signal value. The maximum signal value among these rearranged measuring points is then obtained. The depth location of the pipeline is determined by the position of the depth measuring point corresponding to the maximum signal value. The small spacing d2 should be less than the pipeline diameter or less than a set depth detection limit. This set depth detection limit can be the depth detection limit specified in the current standard "Technical Specification for Fine Detection of Underground Pipelines" or a depth detection limit preset by the construction party.

[0027] Furthermore, there are no fewer than 5 planar survey lines and no fewer than 5 depth survey lines, and each line has no fewer than 5 planar survey points and no fewer than 5 depth survey points.

[0028] Compared with existing technologies, the beneficial effects of this invention are: 1. This detection method directly detects the depth of buried gas PE pipelines, satisfying more testing environments and effectively improving testing accuracy. The testing interface is not limited to various media such as concrete, brick, sand, asphalt, miscellaneous fill, and soil; it can provide more accurate test results for actual projects, thereby effectively reducing the safety risks during pipeline network renovation; 2. This detection method transforms horizontal plane detection into vertical detection, converting the testing surface to the cross-section of the vertical medium, so that the measuring point is in an environment where the medium is uniform soil after a certain depth, resulting in more ideal testing effects and higher accuracy; 3. This detection method first determines the basic direction of the pipeline, and then uses a plane... 4. Accurately determining the planar positioning line of the measuring point, and then setting the vertical points based on the planar positioning line of the pipeline, helps improve the accuracy and effectiveness of vertical point detection; 5. By using planar measuring lines at different intervals and the maximum value of multiple planar measuring points to determine the accurate direction of the pipeline and the planar positioning line, the method can meet the requirements of ±10cm for planar position positioning when the pipeline depth h≤1m, and ±0.1h for planar position positioning when the pipeline burial depth is 1m<h≤5m; 6. Through this method, the testing accuracy of the depth measuring points can meet the requirements of ±15cm for burial depth when the depth h≤1m, and ±0.15h for burial depth when the burial depth is 1m<h≤5m. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the method for determining the pipeline direction in the depth detection method of the present invention;

[0030] Figure 2 This is a schematic diagram of determining the planar positioning line of the pipeline in the depth detection method of the present invention;

[0031] Figure 3 This is a schematic diagram illustrating the determination of vertical points in the depth detection method of the present invention;

[0032] Figure 4 This is a schematic diagram of pipe depth detection in the depth detection method of the present invention;

[0033] Figure 5 This is a schematic diagram of pipe depth calibration in the depth detection method of the present invention;

[0034] Figure 6 This is a schematic diagram illustrating the determination of pipeline direction during blind probing in the depth detection method of the present invention;

[0035] Figure 7 This is a schematic diagram illustrating the impact of planar positioning accuracy on depth detection according to the present invention;

[0036] Figure 8 This is a schematic diagram showing the distribution of signal values ​​when the depth measuring point spacing is 10cm and 40cm in the depth detection method of the present invention.

[0037] In the diagram: 1. Pipeline; 2. Signal transmitting device; 3. Signal receiving device; 4. Horizontal survey line; 5. Horizontal survey point; 6. Vertical point; 7. Depth survey line; 8. Depth survey point. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] like Figures 1-5 As shown, a method for detecting the depth of buried PE pipes includes the following steps:

[0041] Step 1: Determine the basic route of pipeline 1, and set up signal transmitting device 2 on the ground corresponding to pipeline 1;

[0042] Step 2: Arrange several horizontal plane survey lines 4 according to the basic direction. Each plane survey line 4 is provided with a plane survey point 5. A signal receiving device 3 is set at the plane survey point 5. The plane positioning line of the pipeline is determined according to the signal value obtained by the signal receiving device at the plane survey point 5.

[0043] Step 3: Set vertical points 6 according to the planar positioning line of the pipeline, and set a safety distance L between the vertical points 6 and the planar positioning line;

[0044] Step 4: At the vertical point 6, multiple depth measuring lines 7 are arranged vertically downwards from the ground. Depth measuring points 8 are arranged on the depth measuring lines 7. The depth measuring points 8 are connected to a signal receiving device. The depth position of the pipeline is determined based on the signal value obtained by the signal receiving device at the depth measuring point 8.

[0045] This detection method directly detects the depth of buried gas PE pipelines, meeting the requirements of more testing environments and effectively improving testing accuracy. The testing interface is not limited to various media such as concrete, brick, sand, gravel, asphalt, miscellaneous fill, and soil. It can provide more accurate test results for actual projects, thereby effectively reducing the safety risks when modifying pipeline networks.

[0046] Existing testing methods involve ground-based testing followed by fitting or calculation to determine depth. However, in most testing scenarios, the ground surface is composed of various media from top to bottom, and the composition and depth of these media vary significantly across different scenarios. This leads to a substantial reduction in the applicability and accuracy of existing testing solutions. This new detection method transforms horizontal plane detection into depth detection, shifting the testing surface to a cross-section of the vertical medium. This places the measuring point in an environment where the medium becomes uniform soil beyond a certain depth, resulting in more ideal testing results and higher accuracy.

[0047] This detection method first determines the basic direction of the pipeline. After determining the basic direction, it uses planar measuring points to determine the planar positioning line of the pipeline, i.e., the accurate direction of the pipeline. Then, it sets vertical points according to the planar positioning line of the pipeline. This operation helps to improve the accuracy and effectiveness of vertical point detection. The vertical points are set at a safe distance (about 1m apart) on one side of the pipeline to prevent the metal probe from damaging the pipeline during depth detection.

[0048] The basic principle of this detection method is as follows: A set of sound wave signals of a specific frequency is emitted into the pipeline through a signal transmitting device. The sound waves cause the gas particles in the pipeline to vibrate, and the vibrating particles cause the next gas particle to vibrate. While the sound wave signals propagate along the natural gas inside the PE pipeline, they also penetrate the pipe wall, soil, and other media to reach the ground surface. At this point, a signal receiving device on the ground matches the corresponding transmission frequency to receive the sound wave signal. The point with the strongest received signal is considered the direct location of the underground pipeline. By combining multi-point planar positioning tests and multi-point depth tests, and performing linear fitting of the planar and depth coordinates of multiple measuring points, the accurate location of the gas PE pipeline can be obtained.

[0049] Furthermore, in step 1, the basic direction of the pipeline can be determined by the two valves inside the buried vent valve, and the connecting line between the two valves is the direction of the pipeline.

[0050] When conducting blind probing, circular measuring points are placed above the approximate area of ​​the pipeline (gas pipeline markers). The maximum values ​​of the two signals are then read. The basic direction of the pipeline can be determined by connecting the measuring point locations corresponding to these two maximum signal values. The smaller the spacing between the measuring points, the more accurate the pipeline direction. Figure 6 As shown.

[0051] When the pipeline changes direction, find the point S before the signal disappears. Arrange semi-circular measuring points around this point as the center, and then read the maximum signal value. The line connecting point S and the point with the maximum signal value is the basic direction of the pipeline. The smaller the spacing between the semi-circular measuring points, the more accurate the approximate direction of the pipeline.

[0052] Furthermore, before determining the basic route of the pipeline, a signal transmitting device is connected and installed at the pipeline interface.

[0053] Furthermore, in step 2, each of the plane measuring lines is arranged perpendicular to the basic direction of the pipeline, and multiple plane measuring points are arranged at intervals on each of the plane measuring lines. The location of the plane measuring point corresponding to the maximum signal value at multiple plane measuring points on the plane measuring line determines the plane position directly above the pipeline. Based on the multiple plane positions directly above the pipeline determined by the multiple plane measuring lines, the plane positioning line of the pipeline can be determined.

[0054] In other words, for each planar survey line, multiple measuring points are selected for testing. Multiple corresponding signal values ​​are obtained from these measuring points along the same planar survey line. The location of the measuring point corresponding to the maximum value is then used to determine the planar positioning line of the pipeline. This multi-point testing method reduces errors and improves accuracy. Furthermore, the smaller the spacing between the multiple measuring points along the same planar survey line, the higher the positioning accuracy.

[0055] The arrangement of multiple plane measuring points along each plane measuring line involves first arranging several measuring points at equal intervals of a large spacing D1, obtaining the maximum signal value among these points, and then rearranging several measuring points at equal intervals of a small spacing d1, centered on the measuring point corresponding to the maximum signal value. The maximum signal value among these rearranged measuring points is then obtained. The plane position directly above the pipeline is determined by the position of the plane measuring point corresponding to the maximum signal value. The small spacing d1 should be less than the pipeline diameter or less than a pre-defined plane position positioning limit. This pre-defined plane position positioning limit can be the plane position positioning limit specified in the current standard "Technical Specification for Fine Detection of Underground Pipelines," or it can be a plane position positioning limit preset by the construction party.

[0056] Preferably, for each of the aforementioned plane measurement lines, multiple plane measurement points are first selected at 1m intervals, and the maximum value of the signal value among the five plane measurement points is obtained. Then, multiple plane measurement points are rearranged with the maximum value as the center and at 0.1m intervals.

[0057] The detection method using plane measuring points with different intervals can meet the requirement that the plane position positioning error is ±10cm when the pipeline depth h≤1m; and when the pipeline burial depth is 1m<h≤5m, the plane position positioning error is controlled within ±0.1h.

[0058] To further determine the accurate route and horizontal positioning line of the pipeline, proceed a certain distance along the pipeline's extension direction (basic route) and lay out five more survey lines. Each of these horizontal survey lines is denoted as a1, a2, a3, a4, a5, and aN. Determine the maximum signal value at the horizontal survey point on each horizontal survey line using the method described above, and denot them as Maxa1, Maxa2, Maxa3, Maxa4, Maxa5, and MaxaN, respectively. The line formed by connecting the horizontal positions of the pipeline directly above these maximum values ​​determines the accurate route and horizontal positioning line of the pipeline.

[0059] Preferably, the center point of the vent valve is used as the origin of the coordinate system. The extension direction (basic direction) of the pipeline is set as the X-axis, and the straight line perpendicular to the pipeline extension direction and passing through the center of the vent valve is set as the Y-axis, thus constructing a planar coordinate system. The plane coordinates of the plane measuring points corresponding to the maximum signal values ​​Maxa1, Maxa2, Maxa3, Maxa4, Maxa5, and MaxaN are then obtained in this coordinate system, yielding several coordinates of the pipeline's directly above positions. A linear regression equation y=ax+b is used to fit these measuring points to determine the actual position of the pipeline, where x represents the distance from the measuring point to the X-axis, and y represents the distance from the measuring point to the Y-axis. The straight line calculated by this equation is the planar positioning line of the pipeline, representing a more accurate pipeline direction. This method effectively eliminates positioning errors caused by deviations in the maximum value of the test point signal due to uneven geological conditions. The more measuring lines arranged along the pipeline extension direction, the more accurate the horizontal positioning of the pipeline.

[0060] After determining the horizontal positioning line of the pipeline, the position of vertical point b is determined in step 3. To prevent damage to the pipeline during vertical testing, a safety interval must be set. This distance is related to the pipeline diameter; in this embodiment, point b should be more than 1m away from the horizontal positioning line of the pipeline. The signal receiving device used for depth testing is a metal rod. The signal receiving sensor is built into the bottom of the metal rod, which is marked with its depth, allowing direct reading of the sensor's location. During testing, the metal rod needs to be inserted vertically into the test surface in the ground. The test surface may be hard or soft ground. Soft ground allows for direct insertion, while hard ground requires micro-hole excavation before insertion.

[0061] Then, the metal rod is inserted vertically, and depth measuring points are arranged at different depths. The number of depth measuring points should be greater than 5, and the smaller the spacing between the depth measuring points, the higher the accuracy.

[0062] Specifically, multiple depth measuring points are arranged at intervals along each depth measuring line. The depth position of the pipeline is obtained based on the depth identifier of the depth measuring point corresponding to the maximum signal value among the multiple depth measuring points on each depth measuring line. The accurate depth value of the pipeline is determined based on the multiple depth positions of the pipeline determined by the multiple depth measuring lines.

[0063] Preferably, a preliminary test can be conducted first, with 5 depth measurement points and a spacing of 0.5m between them; then, 7 depth measurement points are rearranged with the maximum signal value of these 5 depth measurement points as the center, with a spacing of 0.1m between these 7 depth measurement points. The maximum signal test result among these 7 depth measurement points is the vertical position of the pipe, which can be denoted as Max b1.

[0064] With this operating method, the testing accuracy of the depth measuring point can meet the requirements of ±15cm for depth h≤1m and ±0.15h for depth detection when the depth is 1m<h≤5m.

[0065] To further determine the pipeline depth and reduce errors, starting from point b, proceed a certain distance along the pipeline's extension direction (the pipeline's planar positioning line) and lay out five more depth measurement lines. Each depth measurement line is sequentially labeled b1, b2, b3, b4, b5, and bN. Following the method described above, obtain the maximum signal values ​​at multiple depth measurement points on each depth measurement line, labeled Maxb1, Maxb2, Maxb3, Maxb4, Maxb5, and MaxbN respectively. Connect the depth measurement points corresponding to these maximum values ​​to form a line. The height H of this line above the ground is the accurate depth of the pipeline.

[0066] Preferably, the positioning line is perpendicular to the plane of the pipeline and located at a distance from the center of the vent valve. l Point m is the origin of the coordinate system, and the distance from the pipe plane positioning line is... l The line parallel to m is set as the X-axis, and the direction perpendicular to the ground through the origin is set as the Y-axis, thus constructing a depth coordinate system. Then, the depth coordinates of the depth measuring points corresponding to the maximum values ​​Maxb1, Maxb2, Maxb3, Maxb4, Maxb5, and MaxbN of the above signal are calculated in this depth coordinate system, obtaining several depth position coordinates of the pipeline. Here, X is the horizontal distance from the depth measuring point to the origin, and Y is the depth value from the depth measuring point to the ground. The linear regression equation Y=AX+B is used to fit the above measuring points to determine the pipeline's burial depth. Here, A represents the pipeline's inclination, and B represents the pipeline's depth. Fitting the pipeline depth value using the linear regression equation Y=AX+B eliminates testing errors caused by geological unevenness. The more depth measuring lines arranged along the pipeline's horizontal positioning line, the more accurate the pipeline's depth positioning.

[0067] Preferably, when performing linear fitting on the coordinates of the aforementioned depth positions of the pipeline, outliers should be removed. Preferably, the average depth Vp is first calculated. When the pipeline burial depth is ≤1m, depth measurement points whose depth does not meet Vp±15cm are removed; when the pipeline burial depth is 1m<h≤5m, depth measurement points whose depth does not meet Vp±0.15h are removed. If the number of points actually used in the calculation after removal is less than 5, additional depth measurement points need to be added.

[0068] Preferably, there are no fewer than 5 planar survey lines and no fewer than 5 depth survey lines, and each line has no fewer than 5 planar survey points and no fewer than 5 depth survey points.

[0069] The accuracy of this burial depth detection method is related to both the accuracy of planar positioning and the accuracy of depth detection. In actual underground engineering, pipelines often have turns, tees, etc. If the test is conducted based solely on a basic route that can be directly observed from the vent valve, errors will occur in judging the actual pipeline route (planar positioning) when the underground pipeline changes direction, thus affecting the depth test. Figure 7 As shown, when conducting burial depth tests on a pipeline section after a turn, if the basic direction observed at the vent valve is considered as the entire pipeline direction, and a vertical point b is set based on this pipeline direction, there is a risk of damaging the pipeline during depth testing when the vertical point b is on the same side as the actual pipeline position, which could lead to safety issues. When the vertical point b is on the opposite side of the actual pipeline position, the effective signal cannot be received due to the excessive testing distance, making it impossible to analyze and determine the pipeline depth.

[0070] After ensuring the accuracy of planar positioning, the accuracy of burial depth detection mainly depends on the spacing between depth measuring points on the depth measuring line; the smaller the spacing between measuring points, the higher the accuracy. For example... Figure 8 As shown, taking a practical engineering example, the municipal medium-pressure pipeline is buried at a depth of approximately 1.5m with a diameter of DN200. The measuring point spacing is 10cm and 40cm. When the spacing is 10cm, the maximum signal value falls within the error range, and both the planar detection accuracy and depth accuracy can be controlled within 10cm, meeting the 0.15h requirement of the current standard "Technical Specification for Fine Detection of Underground Pipelines". However, when the spacing is 40cm, the maximum signal value may fall outside the error range. When the burial depth exceeds 0.5m, the medium is a relatively uniform soil layer, so the closer the probe is to the pipeline, the greater the received signal value. However, even in a homogeneous layer, there will be voids or dense areas in the soil, which will change the wave propagation direction. This method determines multiple maximum signal values ​​by adding depth measuring lines and then performing linear regression to fit the depth value, thereby reducing the influence of the heterogeneity of the underground medium and further improving the test accuracy.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the depth of buried PE pipelines, characterized in that, Includes the following steps: Determine the basic route of the pipeline; Several horizontal planar survey lines are arranged according to the basic direction. Planar survey points are set on each of the planar survey lines. A signal receiving device is connected to the planar survey point. The planar positioning line of the pipeline is determined according to the signal value obtained by the signal receiving device at the planar survey point. A number of vertical points are set according to the planar positioning line of the pipeline, and a safety distance L is provided between the vertical points and the planar positioning line; A depth survey line is laid vertically downwards from the ground at the vertical point. Multiple depth survey points are arranged on the depth survey line. The depth survey points are connected to a signal receiving device. The depth position of the pipeline is determined based on the signal value obtained by the signal receiving device at the depth survey point.

2. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, The basic direction of the pipeline can be determined by using buried vent valves, or by using circular points at any location on the ground to determine the basic direction of the pipeline; a signal transmitting device can be installed on the ground corresponding to the pipeline vent valve.

3. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, Each of the aforementioned planar survey lines is arranged perpendicular to the basic direction of the pipeline. Multiple planar survey points are arranged at intervals along each of the aforementioned planar survey lines. The location of the planar survey point corresponding to the maximum signal value at the multiple planar survey points on the planar survey line determines the planar position directly above the pipeline. The planar positioning line of the pipeline is determined based on the multiple planar positions directly above the pipeline determined by the multiple planar survey lines.

4. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, Each of the aforementioned planar measurement lines is sequentially denoted as a1, a2, a3, ..., aN, where N is a positive integer. The maximum value of the signal at multiple planar measurement points on each of the aforementioned planar measurement lines is obtained and denoted as Maxa1, Maxa2, Maxa3, ..., MaxaN, respectively. The positions of the planar measurement points corresponding to these maximum signal values ​​are fitted by a linear regression equation to determine the planar positioning line of the pipeline.

5. The method for detecting the depth of buried PE pipelines according to claim 3, characterized in that, The arrangement of multiple plane measuring points on each plane measuring line is as follows: First, several measuring points are arranged at equal intervals with a large spacing D1 to obtain the maximum value of the signal value among the several measuring points with the large spacing. Then, several measuring points are rearranged at equal intervals with a small spacing d1, with the measuring point corresponding to the maximum value of the signal value as the center, and the maximum value of the signal value among the several rearranged measuring points is obtained. The plane position directly above the pipeline is determined by the position of the plane measuring point corresponding to the maximum value of the signal value. The value of the small spacing d1 should be less than the pipe diameter or less than the set planar position positioning limit.

6. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, A metal rod is inserted vertically downwards from the vertical point on the ground or inserted through a hole to form the depth measurement line. The metal rod has a built-in signal receiving sensor and is marked with depth information to read the depth position of the signal receiving sensor.

7. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, Multiple depth measuring points are arranged at intervals along each depth measuring line. The depth position of the pipeline is obtained based on the depth identifier of the depth measuring point corresponding to the maximum signal value among the multiple depth measuring points on each depth measuring line. The accurate depth value of the pipeline is determined based on the multiple depth positions of the pipeline determined by the multiple depth measuring lines.

8. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, The vertical points are all laid out perpendicular to the planar positioning line. The depth measuring lines pass through the vertical points and are arranged in a direction parallel to the planar positioning line. Each depth measuring line is sequentially denoted as b1, b2, b3, ..., bN, where N is a positive integer. The maximum value of the signal at multiple depth measuring points on each depth measuring line is obtained and denoted as Maxb1, Maxb2, Maxb3, ..., MaxbN, respectively. The depth value of the pipeline is determined by fitting the position of the depth measuring point corresponding to the maximum value of these signal values ​​through a linear regression equation.

9. The method for detecting the depth of buried PE pipelines according to claim 7, characterized in that, The arrangement of multiple depth measuring points on each depth measuring line involves first arranging several measuring points at equal intervals with a large spacing of D2, obtaining the maximum signal value among these measuring points at this large spacing, then rearranging several measuring points at equal intervals with a small spacing of d2, centering on the measuring point corresponding to the maximum signal value, and obtaining the maximum signal value among the rearranged measuring points. The depth location of the pipeline is determined by the position of the depth measuring point corresponding to the maximum signal value. The small spacing d2 should be less than the pipeline diameter or less than the set burial depth detection limit.

10. The method for detecting the depth of buried PE pipelines according to claim 1, characterized in that, There are no fewer than 5 planar survey lines and no fewer than 5 depth survey lines, and each line has no fewer than 5 planar survey points and no fewer than 5 depth survey points.

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