Method for detecting depth of buried PE (Poly Ethylene) pipeline

Abstract

The invention discloses a buried PE pipeline depth detection method. The method comprises the steps that the basic trend of a pipeline is determined; a plurality of horizontal plane measuring lines are arranged according to the basic trend, each plane measuring line is provided with a plane measuring point, and a plane positioning line of the pipeline is determined according to a signal value obtained by a signal receiving device at the plane measuring point; a vertical point location is arranged according to the plane positioning line of the pipeline, a depth measuring line is downwards arranged at the vertical point location perpendicular to the ground, a depth measuring point is arranged on the depth measuring line, and the depth position of the pipeline is determined according to a signal value obtained by a signal receiving device at the depth measuring point. According to the detection method, the depth position of the buried gas PE pipeline is detected through a direct method, more test environments are met, and the test accuracy can be effectively improved; and a more accurate test result can be provided for actual engineering, so that the safety risk during pipe network transformation is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of gas pipeline detection, and in particular to a method for depth detection of buried PE pipelines. Background Art

[0002] If the gas pipeline information system is not perfect, it may cause natural gas leakage, explosion and even casualties. Therefore, accurate positioning of buried gas PE pipelines is particularly important to ensure the safety of urban construction.

[0003] Since PE pipes are non-conductive, non-magnetic, and basically insulated, conventional detection methods cannot accurately locate them. At present, there are many technologies and methods for accurately locating gas PE pipes, such as ground penetrating radar (large detection depth limit, high requirements for testers, inaccurate test results), electromagnetic induction method (completely unable to test without tracer line), but the above methods all have obvious disadvantages. The use of active sound source method for PE pipe positioning detection is widely used.

[0004] In recent years, with the development of science and technology, the method of using active sound source method to locate and detect PE pipelines has become increasingly mature. However, this method can only achieve accurate positioning of the plane position of the pipeline, and the detection of depth is still in its infancy. At present, depth positioning mostly uses time difference method, multi-point / matrix fitting method, and calibration empirical value method. The above methods are all indirect or simulation test methods, which are suitable for completely homogeneous ideal interfaces. In the actual test process, they are greatly restricted by the test scene and the test accuracy is relatively low.

[0005] The time difference method and multi-point / matrix fitting method are mainly used to test the relationship between time, distance and wave speed at different points. Since the active sound source method uses low frequency, the time difference collected at different measuring points is at the microsecond level, and the magnitude of the time deviation caused by the uneven medium is much larger than the time difference between different distances. This will cause the test accuracy to be greatly affected by the test environment and the test accuracy is extremely low. The calibration empirical value rule is to test the intensity of different points at different depths of a certain medium and then fit it. Then the intensity obtained by the test is compared with the estimated depth. It is difficult to keep the test environment consistent, so the accuracy of the test results is relatively low, and a lot of calibration work is required for each test environment, which is relatively complicated overall.

[0006] For example, a Chinese invention patent application (publication number: CN116224340A) records a non-metallic gas pipeline positioning calculation method, which applies an acoustic vibration signal of a selectable frequency to generate an oscillation wave signal in the natural gas in the pipeline, and propagates it along the pipeline to the far end. This method assumes that the propagation speed of the medium in the covering layer above the pipeline at different measuring points is consistent. However, in the actual test process, the medium above the pipeline is divided into multiple layers, and the test results will have errors of several orders of magnitude.

[0007] Another example is a Chinese invention patent application (publication number: CN113759358A) that describes a method for detecting buried pipelines. Based on the horizontal coordinates of the pipelines underground, the buried depth of the pipelines is measured by radar directly above the pipelines. This solution uses ground penetrating radar to obtain the depth, but the radar has a limited test depth and cannot overcome the influence of multiple layers of media above the pipelines.

[0008] In summary, these solutions may only be applicable to environmental testing of pure soil media, but the actual major safety hazards are buried gas pipelines in municipalities or communities, whose interfaces include multiple media such as concrete, bricks, sand and gravel, asphalt, miscellaneous fill and soil. The presence of these multiple media will greatly reduce the accuracy of detection. Summary of the invention

[0009] The purpose of the present invention is to provide a method for detecting the depth of a buried PE pipeline in view of the problems existing in the prior art.

[0010] To achieve the above object, the technical solution adopted by the present invention is: A method for detecting the depth of a buried PE pipeline comprises the following steps: Determine the basic direction of the pipeline; Arrange a plurality of horizontal plane measuring lines according to the basic direction, each plane measuring line is provided with a plane measuring point, a signal receiving device is connected to the plane measuring point, and the plane positioning line of the pipeline is determined according to the signal value obtained by the signal receiving device at the plane measuring point; A vertical point is set according to the plane positioning line of the pipeline, and a safety distance L is set between the vertical point and the plane positioning line; A depth measurement line is arranged perpendicularly downward from the ground at the vertical point, and a plurality of depth measurement points are arranged on the depth measurement line. The depth measurement points are connected to a signal receiving device, and the depth position of the pipeline is determined according to the signal value obtained by the signal receiving device at the depth measurement point.

[0011] This detection method is to detect the depth position of the buried gas PE pipeline through a direct method, which meets more test environments and can effectively improve the test accuracy; it can provide more accurate test results for actual projects, thereby effectively reducing the safety risks when renovating the pipeline network.

[0012] This detection method converts the horizontal detection into the vertical detection, and converts the test surface into the cross section of the vertical medium, so that the measuring point is in an environment where the medium is uniform soil after the depth exceeds a certain range, and the test effect is more ideal and the accuracy will be higher. This detection method first determines the basic direction of the pipeline, and after determining the basic direction of the pipeline, uses the plane measuring point to accurately determine its plane positioning line, and then sets the vertical point according to the plane positioning line of the pipeline. Such operation is conducive to improving the accuracy and effectiveness of vertical point detection.

[0013] Furthermore, the basic direction of the pipeline is determined by an underground relief valve, or a circular distribution is performed at any position on the ground to determine the basic direction of the pipeline; a signal transmitting device is set at the corresponding pipeline relief valve on the ground.

[0014] Furthermore, each of the plane measuring lines is arranged perpendicular to the basic direction of the pipeline, and a plurality of the plane measuring points are arranged at intervals on each of the plane measuring lines. The position of the plane measuring point corresponding to the maximum signal value at the plurality of plane measuring points on the plane measuring line determines the plane position directly above the pipeline. The plane positioning line of the pipeline can be determined based on the plurality of plane positions directly above the pipeline determined on the plurality of plane measuring lines.

[0015] Furthermore, each of the plane measuring lines is sequentially recorded as a1, a2, a3, ..., aN, where N is a positive integer, and the maximum value of the signal values ​​at multiple plane measuring points on each of the plane measuring lines is obtained, which are recorded as Maxa1, Maxa2, Maxa3, ..., MaxaN, respectively. The positions of the plane measuring points corresponding to the maximum signal values ​​are fitted by a one-dimensional linear regression equation to determine the plane positioning line of the pipeline.

[0016] That is, for each plane measurement line, multiple measurement points will be selected for detection. Multiple corresponding signal values ​​will be obtained through multiple plane measurement points on the same plane measurement line. The plane measurement point position corresponding to the maximum value is selected, and the plane positioning line where the pipeline is located can be determined. This multi-point testing method can reduce errors and improve accuracy. Moreover, the smaller the spacing between multiple plane measurement points on the same plane measurement line, the higher the positioning accuracy.

[0017] Furthermore, the arrangement of multiple plane measuring points on each plane measuring line is to first arrange several measuring points at equal intervals according to a large spacing D1, obtain the maximum value of the signal value among the several measuring points under the large spacing, and then rearrange several measuring points at equal intervals according to a small spacing d1 with the measuring point corresponding to the maximum value of the signal value as the center, obtain the maximum value of the signal value among the rearranged several measuring points, and determine the plane position directly above the pipeline with the position of the plane measuring point corresponding to the maximum value of the signal value; wherein the value of the small spacing d1 should be smaller than the diameter of the pipeline, or smaller than the set plane position positioning tolerance. The set plane position positioning tolerance can be the plane position positioning tolerance specified in the current specification "Technical Regulations for Fine Detection of Underground Pipelines", or it can be the plane position positioning tolerance preset by the construction party.

[0018] Furthermore, a metal drill rod is inserted vertically downward from the vertical point or inserted through a hole to form the depth measurement line. The metal drill rod has a built-in signal receiving sensor. The depth is marked on the metal drill rod, and the depth position of the signal receiving sensor can be directly read.

[0019] Furthermore, a plurality of the depth measuring points are arranged at intervals on each of the depth measuring lines, and the depth position of the pipeline is obtained according to the depth identifier of the depth measuring point corresponding to the maximum signal value among the plurality of depth measuring points on each of the depth measuring lines, and the accurate depth value of the pipeline is determined according to the plurality of depth positions of the pipeline determined on the plurality of depth measuring lines.

[0020] Furthermore, the vertical points are arranged perpendicular to the plane positioning line, and the depth measurement line passes through the vertical points and is arranged in a direction parallel to the plane positioning line. Each of the depth measurement lines is sequentially recorded as b1, b2, b3, ..., bN, where N is a positive integer. The maximum value of the signal value at multiple depth measurement points on each depth measurement line is obtained, which are recorded as Maxb1, Maxb2, Maxb3, ..., MaxbN respectively. The positions of the plane measurement points corresponding to the maximum signal values ​​are fitted by a one-dimensional linear regression equation to determine the depth value of the pipeline. Fitting the depth value of the pipeline in this way can eliminate the test error caused by uneven geology. The more measurement lines are arranged along the extension direction of the pipeline, the more accurate the depth positioning of the pipeline will be.

[0021] The arrangement of multiple depth measuring points on each depth measuring line is to first arrange several measuring points at equal intervals according to a large spacing D2, obtain the maximum value of the signal value among several measuring points under the large spacing, and then rearrange several measuring points at equal intervals according to a small spacing d2 with the measuring point corresponding to the maximum signal value as the center, obtain the maximum value of the signal value among the rearranged several measuring points, and determine the depth position of the pipeline with the position of the depth measuring point corresponding to the maximum signal value; wherein the value of the small spacing d2 should be smaller than the diameter of the pipeline, or smaller than the set buried depth detection limit. The set buried depth detection limit can be the buried depth detection limit specified in the current specification "Technical Regulations for Fine Detection of Underground Pipelines", or it can be the buried depth detection limit preset by the construction party.

[0022] Furthermore, there are no less than 5 plane measuring lines and no less than 5 depth measuring lines, and there are no less than 5 plane measuring points and no less than 5 depth measuring points on each line.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. This detection method detects the depth position of the buried gas PE pipeline through a direct method, which meets more test environments and can effectively improve the test accuracy. The test interface is not limited to concrete, bricks, sand and gravel, asphalt, miscellaneous fill and soil and other media; it can provide more accurate test results for actual projects, thereby effectively reducing the safety risks when transforming the pipeline network; 2. This detection method converts the horizontal plane detection into a longitudinal detection, and converts the test surface into a cross-section of the vertical medium, so that the measuring point is in an environment where the medium is uniform soil after the depth exceeds a certain range, the test effect is more ideal, and the accuracy will be higher; 3. This detection method first determines the basic direction of the pipeline, and then uses the plane to determine the basic direction of the pipeline. The measuring point accurately determines its plane positioning line, and then sets the vertical point according to the plane positioning line of the pipeline. Such operation is conducive to improving the accuracy and effectiveness of vertical point detection; 4. The accurate direction and plane positioning line of the pipeline are determined by the maximum value of plane measuring lines with different spacings and multiple plane measuring points. It can meet the requirements of ±10cm for the plane position positioning limit when the pipeline depth is h≤1m, and ±0.1h for the plane position positioning limit when the pipeline burial depth is 1m<h≤5m; 5. Through this operation mode of this method, the test accuracy of the depth measuring point can meet the requirements of ±15cm for the burial depth detection limit when the depth is h≤1m, and ±0.15h for the burial depth detection limit when the burial depth is 1m<h≤5m. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of determining the direction of a pipeline in the depth detection method of the present invention; Figure 2 A schematic diagram of determining a plane positioning line of a pipeline in the depth detection method of the present invention; Figure 3A schematic diagram of determining a vertical point position in the depth detection method of the present invention; Figure 4 It is a schematic diagram of pipeline depth detection in the depth detection method of the present invention; Figure 5 It is a schematic diagram of pipeline depth calibration in the depth detection method of the present invention; Figure 6 It is a schematic diagram of determining the direction of a pipeline during blind detection in the depth detection method of the present invention; Figure 7 It is a schematic diagram of the influence of plane positioning accuracy on depth detection of the present invention; Figure 8 It is a schematic diagram of the distribution of signal values ​​when the depth measurement point spacing is 10 cm and 40 cm in the depth detection method of the present invention; In the figure: 1. Pipeline; 2. Signal transmitting device; 3. Signal receiving device; 4. Plane measuring line; 5. Plane measuring point; 6. Vertical point; 7. Depth measuring line; 8. Depth measuring point. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as "middle", "upper", "lower", "left", "right", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0027] like Figure 1 to Figure 5 As shown, a method for detecting the depth of a buried PE pipeline comprises the following steps: Step 1: Determine the basic direction of the pipeline 1 and set a signal transmitter 2 on the ground corresponding to the pipeline 1; Step 2: Arrange a plurality of horizontal plane measuring lines 4 according to the basic direction, each plane measuring line 4 is provided with a plane measuring point 5, a signal receiving device 3 is arranged at the plane measuring point 5, and determine the plane positioning line of the pipeline according to the signal value obtained by the signal receiving device at the plane measuring point 5; Step 3: a vertical point 6 is set according to the plane positioning line of the pipeline, and a safety distance L is set between the vertical point 6 and the plane positioning line; Step 4: Arrange multiple depth measurement lines 7 perpendicular to the ground at the vertical point 6, and arrange depth measurement points 8 on the depth measurement lines 7. The depth measurement points 8 are connected to signal receiving devices, and the depth position of the pipeline is determined according to the signal values ​​obtained by the signal receiving devices at the depth measurement points 8.

[0028] This detection method is to detect the depth position of the buried gas PE pipeline through a direct method, which meets more test environments and can effectively improve the test accuracy. The test interface is not limited to concrete, bricks, gravel, asphalt, miscellaneous fill and soil and other media; it can provide more accurate test results for actual projects, thereby effectively reducing the safety risks when renovating the pipeline network.

[0029] The existing test method is to test on the ground and then fit or calculate to get the depth. In most test scenarios, the test surface from top to bottom of the ground is composed of multiple media, and the composition and depth of the media in different scenarios are very different, which will greatly reduce the applicability and accuracy of the existing test scheme. This detection method converts the horizontal plane detection into depth detection, and converts the test surface into a cross-section of the vertical medium, so that the measuring point is in an environment where the medium is uniform soil after the depth exceeds a certain range, and the test effect is more ideal and the accuracy will be higher.

[0030] This detection method first determines the basic direction of the pipeline. After determining the basic direction of the pipeline, the plane measuring points are used to determine the plane positioning line of the pipeline, that is, the accurate direction of the pipeline. Then, vertical points are set according to the plane positioning line of the pipeline. Such operation is conducive to improving 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, which can prevent the metal drill rod from damaging the pipeline during depth detection.

[0031] The basic principle of this detection method is: a set of sound wave signals of a specific frequency is emitted into the pipeline through a signal transmitting device. The sound waves drive the gas particles in the pipeline to vibrate, and the vibrating particles drive the next gas particle to vibrate. While the sound wave signal propagates along the natural gas in the PE pipeline, it passes through the pipe wall, soil and other media to reach the surface. At this time, the sound wave signal is received by matching the corresponding transmission frequency on the ground through a signal receiving device. The point with the maximum signal intensity is considered to be the opposite position of the underground pipeline. A combination of multi-point plane positioning test and multi-point depth test is adopted. The accurate position of the gas PE pipeline can be obtained by linearly fitting the plane position coordinates and depth position coordinates of multiple measuring points.

[0032] Furthermore, in step 1, the basic direction of the pipeline can be determined by two valves in the buried relief valve, and the connection line between the two valves is the direction of the pipeline.

[0033] When blind detection is performed, circular measuring points are arranged above the approximate area of ​​the pipeline (gas pipeline identification point), and then the two signal maxima are read. The basic direction of the pipeline can be determined through the connecting line of the two signal maxima corresponding to the measuring point positions. The smaller the spacing between the measuring points, the more accurate the direction of the pipeline. Figure 6 shown.

[0034] When the pipeline turns, find the previous point S where the signal disappears and arrange semicircular measuring points on the periphery with this point as the center. Then read the maximum signal value. The line connecting point S and the point of the maximum signal value is the basic direction of the pipeline. The smaller the spacing between the semicircular measuring points, the more accurate the approximate direction of the pipeline.

[0035] Furthermore, before determining the basic direction of the pipeline, a signal transmitter is connected and installed at the pipeline interface in advance.

[0036] Furthermore, in step 2, each of the plane measuring lines is arranged perpendicular to the basic direction of the pipeline, and a plurality of the plane measuring points are arranged at intervals on each of the plane measuring lines. The position of the plane measuring point corresponding to the maximum signal value at the plurality of plane measuring points on the plane measuring line determines the plane position directly above the pipeline. The plane positioning line of the pipeline can be determined based on the plurality of plane positions directly above the pipeline determined on the plurality of plane measuring lines.

[0037] That is, for each plane measurement line, multiple measurement points will be selected for detection. Multiple corresponding signal values ​​will be obtained through multiple plane measurement points on the same plane measurement line. The plane measurement point position corresponding to the maximum value is selected, and the plane positioning line where the pipeline is located can be determined. This multi-point testing method can reduce errors and improve accuracy. Moreover, the smaller the spacing between multiple plane measurement points on the same plane measurement line, the higher the positioning accuracy.

[0038] The arrangement of multiple plane measuring points on each plane measuring line is to first arrange several measuring points at equal intervals according to a large spacing D1, obtain the maximum value of the signal value among several measuring points under the large spacing, and then rearrange several measuring points at equal intervals according to a small spacing d1 with the measuring point corresponding to the maximum signal value as the center, obtain the maximum value of the signal value among the rearranged several measuring points, and determine the plane position directly above the pipeline with the position of the plane measuring point corresponding to the maximum signal value; wherein the value of the small spacing d1 should be less than the diameter of the pipeline, or less than the set plane position positioning tolerance. The set plane position positioning tolerance can be the plane position positioning tolerance specified in the current specification "Technical Regulations for Fine Detection of Underground Pipelines", or it can be the plane position positioning tolerance preset by the construction party.

[0039] Preferably, for each of the plane measuring lines, a plurality of plane measuring points are first selected at intervals of 1 m, the maximum value of the signal values ​​among the five plane measuring points is obtained, and the plurality of plane measuring points are rearranged at intervals of 0.1 m with the maximum value as the center.

[0040] The detection performed by selecting plane measuring points at different intervals can meet the requirement that the plane position positioning limit is ±10cm when the pipeline depth is h≤1m; and when the pipeline burial depth is 1m<h≤5m, the plane position positioning limit is controlled within ±0.1h.

[0041] In order to further determine the accurate direction and plane positioning line of the pipeline, advance a certain distance along the extension direction (basic direction) of the pipeline and arrange 5 survey lines again. Each of the plane survey lines is recorded as a1, a2, a3, a4, a5, and aN respectively. The maximum value of the signal value at the plane measuring point on each plane survey line is determined according to the above method, and is recorded as Maxa1, Maxa2, Maxa3, Maxa4, Maxa5, and MaxaN respectively. The lines formed by the plane positions directly above the pipeline corresponding to these maximum values ​​are connected to determine the accurate direction and plane positioning line of the pipeline.

[0042] Preferably, the center point of the relief valve is used as the coordinate origin, the extension direction (basic direction) of the pipeline is set as the X-axis, and the straight line perpendicular to the extension direction of the pipeline and passing through the center of the relief valve is set as the Y-axis, and a plane coordinate system is constructed accordingly. Then, the plane coordinates of the plane measuring points corresponding to the maximum values ​​of the above-mentioned signal values ​​Maxa1, Maxa2, Maxa3, Maxa4, Maxa5, and MaxaN in the plane coordinate system are obtained, that is, several coordinates of the position directly above the pipeline are obtained. These measuring points are fitted using the linear regression equation y=ax+b 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 plane positioning line of the pipeline, which represents a more accurate pipeline direction. This method can effectively eliminate the positioning error caused by the deviation of the maximum value of the test point signal due to the elimination of geological unevenness. The more measuring lines are arranged along the extension direction of the pipeline, the more accurate the horizontal positioning of the pipeline.

[0043] After determining the plane positioning line of the pipeline, determine the position of the vertical point b in step 3. In order to prevent the pipeline from being damaged during the vertical test, a safety interval needs to be set. The distance is related to the diameter of the pipeline. In this embodiment, point b should be greater than 1m away from the plane positioning line of the pipeline. The signal receiving device used in the depth test is a metal drill rod. The signal receiving sensor is built into the bottom end of the metal drill rod. The depth is marked on the drill rod, and the depth position of the receiving sensor can be directly read. During the test, the metal drill rod needs to be inserted into the underground test section in the vertical direction. The test section may be hard ground or soft ground. The soft ground can be inserted directly, and the hard ground needs to be inserted after micro-hole excavation.

[0044] Then the metal drill rod is inserted in the vertical direction, and the depth measuring points are arranged at different depths. The number of the depth measuring points is preferably greater than 5. The smaller the spacing between the depth measuring points, the higher the accuracy.

[0045] Specifically, a plurality of the depth measuring points are arranged at intervals on each of the depth measuring lines, and the depth position of the pipeline is obtained according to the depth identifier of the depth measuring point corresponding to the maximum signal value among the plurality of depth measuring points on each of the depth measuring lines, and the accurate depth value of the pipeline is determined according to the plurality of depth positions of the pipeline determined on the plurality of depth measuring lines.

[0046] Preferably, a preliminary test can be performed first, with 5 depth measuring points and a spacing of 0.5m between the depth measuring points; then, 7 depth measuring points are rearranged with the maximum signal value of these five depth measuring points as the center, and the spacing between these 7 depth measuring points is 0.1m. The maximum value of the signal test results among these 7 depth measuring points is the vertical position of the pipeline, which can be recorded as Max b1.

[0047] Through this operation mode, the test accuracy of the depth measurement point can meet the requirements of the buried depth detection limit error of ±15cm when the depth h≤1m; and the buried depth detection limit error of ±0.15h when the buried depth is 1m<h≤5m.

[0048] In order to further determine the depth of the pipeline and reduce the error, take b as the starting point and advance a certain distance along the direction parallel to the extension of the pipeline (the plane positioning line of the pipeline), and arrange 5 depth measuring lines again. Each of the depth measuring lines is recorded as b1, b2, b3, b4, b5, and bN respectively. According to the above method, the maximum value of the signal value at multiple depth measuring points on each depth measuring line is obtained, which are recorded as Maxb1, Maxb2, Maxb3, Maxb4, Maxb5, and MaxbN respectively. The depth measuring points corresponding to these maximum values ​​are connected into a line. The height H of this line from the ground is the accurate depth of the pipeline.

[0049] Preferably, the plane positioning line perpendicular to the pipeline is located at a distance from the center of the relief valve. l m is the origin of coordinates, and the distance from the pipeline plane positioning linel The parallel line of m is set as the X-axis, and the direction through the origin perpendicular to the ground is set as the Y-axis, and the depth coordinate system is constructed accordingly. Then calculate the depth coordinates of the depth measurement points corresponding to the maximum values ​​of the above signal values ​​Maxb1, Maxb2, Maxb3, Maxb4, Maxb5, and MaxbN in the depth coordinate system, that is, obtain several depth position coordinates of the pipeline, where X is the horizontal distance from the depth measurement point to the origin, and Y is the depth value from the depth measurement point to the ground. The above measurement points are fitted using the linear regression equation Y=AX+B to determine the buried depth of the pipeline. Where A represents the inclination of the pipeline, and B represents the depth of the pipeline. The depth value of the pipeline is fitted by the linear regression equation Y=AX+B to eliminate the test error caused by uneven geology. The more depth measurement lines are arranged along the plane positioning line of the pipeline, the more accurate the depth positioning of the pipeline will be.

[0050] Preferably, when performing linear fitting on the above-mentioned several depth position coordinates of the pipeline, outliers should be eliminated. Preferably, the average value Vp of the depth is first calculated. When the buried depth of the pipeline is ≤1m, the depth measurement points whose depth does not meet Vp±15cm are eliminated; when the buried depth of the pipeline is 1m<h≤5m, the depth measurement points whose depth does not meet Vp±0.15h are eliminated. When the number of points actually involved in the calculation after elimination is less than 5, it is necessary to add depth test points.

[0051] Preferably, the number of the plane measuring lines and the number of the depth measuring lines are no less than 5, and the number of the plane measuring points and the number of the depth measuring points on each line are no less than 5.

[0052] The depth detection accuracy of this detection method is related to the plane positioning accuracy and depth detection accuracy. In actual underground projects, pipelines generally have turns and tees. If the test is only based on a basic direction that can be directly observed by the relief valve, when the underground pipeline turns, the actual direction of the pipeline (plane positioning) will be misjudged, which will affect the depth test. Figure 7 As shown, when the buried depth test is carried out on the pipeline section after the turn, if the basic direction of a section observed at the relief valve is regarded as the direction of the entire pipeline section, and the vertical point b is set based on the pipeline direction, when the vertical point b is on the same side as the actual position of the pipeline, there is a risk of damaging the pipeline during the depth test, thereby inducing safety problems; when the vertical point b is on the opposite side of the actual position of the pipeline, the effective signal cannot be received due to the long test distance, and the pipeline depth cannot be analyzed and determined.

[0053] After ensuring the plane positioning accuracy, the depth detection accuracy also depends mainly on the depth measurement point spacing on the depth measurement line. The smaller the measurement point spacing, the more accurate the accuracy. Figure 8As shown in the figure, taking the actual project as an example, the buried depth of the municipal medium-pressure pipeline is about 1.5m, the pipe diameter is DN200, and the measurement point spacing is 10cm and 40cm respectively. When the spacing is 10cm, the maximum signal value falls within the error range, and the plane detection accuracy and depth accuracy can be controlled within 10cm, meeting the 0.15h requirement of the current specification "Technical Regulations for Fine Detection of Underground Pipelines", while the maximum signal value may fall outside the error range when the spacing is 40cm. When the buried depth exceeds 0.5m, the medium is a relatively uniform soil layer, so the closer the drill rod is to the pipeline during propagation, the greater the signal value it receives. However, even in a homogeneous layer, there will be cavities or dense areas of soil, which will change the propagation direction of the wave in this case. This method adds depth measurement lines to determine multiple signal maxima and then performs linear regression to fit the depth value to reduce the impact of uneven underground media and further improve the test accuracy.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the depth of a buried PE pipeline, characterized in that: The steps include: Determine the basic direction of the pipeline; Arrange a plurality of horizontal plane measuring lines according to the basic direction, each plane measuring line is provided with a plane measuring point, a signal receiving device is connected to the plane measuring point, and the plane positioning line of the pipeline is determined according to the signal value obtained by the signal receiving device at the plane measuring point; A plurality of vertical points are set according to the plane positioning line of the pipeline, and a safety distance L is set between the vertical points and the plane positioning line; A depth measurement line is arranged perpendicularly downward from the ground at the vertical point, and a plurality of depth measurement points are arranged on the depth measurement line. The depth measurement points are connected to a signal receiving device, and the depth position of the pipeline is determined according to the signal value obtained by the signal receiving device at the depth measurement point.

2. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: The basic direction of the pipeline is determined by buried relief valves, or by circular distribution at any position on the ground; a signal transmitter is arranged at the corresponding pipeline relief valve on the ground.

3. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: Each of the plane measuring lines is arranged perpendicular to the basic direction of the pipeline, and a plurality of the plane measuring points are arranged at intervals on each of the plane measuring lines. The position of the plane measuring point corresponding to the maximum signal value at the plurality of plane measuring points on the plane measuring line determines the plane position directly above the pipeline, and the plane positioning line of the pipeline is determined according to the plurality of plane positions directly above the pipeline determined on the plurality of plane measuring lines.

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

5. The method for detecting the depth of a buried PE pipeline according to claim 3, characterized in that: Arrangement of multiple plane measuring points on each plane measuring line, firstly arrange a number of measuring points at equal intervals with a large spacing D1, obtain the maximum value of the signal values ​​among the number of measuring points under the large spacing, then rearrange a number of measuring points at equal intervals with a small spacing d1 with the measuring point corresponding to the maximum value of the signal value as the center, obtain the maximum value of the signal values ​​among the rearranged number of measuring points, and determine the plane position directly above the pipeline with 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 smaller than the pipe diameter, or smaller than the set plane position positioning tolerance.

6. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: The metal drill rod is inserted vertically downward from the vertical point or inserted into a hole to form the depth measurement line. The metal drill rod has a built-in signal receiving sensor. The depth is marked on the metal drill rod for reading the depth position of the signal receiving sensor.

7. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: A plurality of the depth measuring points are arranged at intervals on each of the depth measuring lines, and the depth position of the pipeline is obtained according to the depth identifier of the depth measuring point corresponding to the maximum signal value among the plurality of depth measuring points on each of the depth measuring lines, and the accurate depth value of the pipeline is determined according to the plurality of depth positions of the pipeline determined on the plurality of depth measuring lines.

8. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: The vertical points are arranged perpendicular to the plane positioning line, the depth measuring lines pass through the vertical points and are arranged in a direction parallel to the plane positioning line, each of the depth measuring lines is sequentially recorded as b1, b2, b3, ..., bN, N is a positive integer, and the maximum value of the signal values ​​at multiple depth measuring points on each depth measuring line is obtained, which are respectively recorded as Maxb1, Maxb2, Maxb3, ..., MaxbN, and the positions of the depth measuring points corresponding to the maximum signal values ​​are fitted by a one-dimensional linear regression equation to determine the depth value of the pipeline.

9. The method for detecting the depth of a buried PE pipeline according to claim 7, characterized in that: The arrangement of multiple depth measuring points on each depth measuring line is as follows: first, a number of measuring points are arranged at equal intervals according to a large spacing D2, and the maximum value of the signal values ​​among the several measuring points under the large spacing is obtained; then, a number of measuring points are rearranged at equal intervals according to a small spacing d2 with the measuring point corresponding to the maximum signal value as the center, and the maximum value of the signal values ​​among the rearranged several measuring points is obtained; the depth position of the pipeline is determined by the position of the depth measuring point corresponding to the maximum signal value; wherein the value of the small spacing d2 should be smaller than the pipeline diameter, or smaller than the set buried depth detection limit.

10. The method for detecting the depth of a buried PE pipeline according to claim 1, characterized in that: There are no less than 5 plane measuring lines and no less than 5 depth measuring lines, and there are no less than 5 plane measuring points and no less than 5 depth measuring points on each plane measuring line.

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