Underground Pipeline Detection System and Method Based on Directional Source-Well Electromagnetic Induction

Abstract

This invention discloses an underground pipeline detection system and method based on directional source-well electromagnetic induction. The system includes a magnetic field source module for generating a ring-shaped magnetic field in the target pipeline, a vertically downward-facing well located on one side of the target pipeline, a measuring coil, a drive module, a measurement module, and a calculation module. The plane of the measuring coil forms an acute angle with the horizontal plane. The drive module drives the measuring coil to rotate and move up and down, changing the magnitude of the magnetic flux and the depth of its position. The measurement module obtains the depth, rotation angle, and magnetic flux of the measuring coil. The calculation module calculates the position of the target pipeline relative to the well based on the position of the measuring coil obtained by the measurement module and the corresponding magnetic flux at that position. The system calculates the positional relationship of the target pipeline relative to the well based on the electromagnetic induction characteristics in the well. The calculated position has small error, short acquisition cycle, low cost, strong anti-interference capability, and accurate detection results, thus better meeting the needs of practical detection.

Description

Technical Field

[0001] This invention relates to underground pipeline detection equipment, specifically to an underground pipeline detection system and method based on directional source-well electromagnetic induction. Background Technology

[0002] Underground pipelines are a crucial component of urban infrastructure, serving as the "lifeline" for the normal operation of a city. Currently, underground pipelines are often laid using trenchless methods. However, due to their deep burial depth and irregular horizontal distribution, the accuracy of trenchless pipeline detection cannot be guaranteed. Furthermore, due to widespread mismanagement, relevant data on these concealed pipelines is lacking and distorted, making trenchless pipelines a significant hidden danger in the development of underground space during engineering construction.

[0003] Limitations of Existing Pipeline Detection Methods. Commonly used underground pipeline detection methods include ground electromagnetic induction, ground penetrating radar, high-density resistivity method, and borehole magnetic gradient method. Ground electromagnetic induction is essentially ineffective when pipeline burial depth exceeds 3m; the detection range of ground penetrating radar is significantly affected by underground media and cannot be used in silty cities; the high-density resistivity method is cumbersome to operate; and the borehole magnetic gradient method has a short detection range and lacks theoretical analysis methods for precise pipeline location. It can be seen that existing methods suffer from drawbacks such as low detection accuracy, small detection range, or cumbersome operation. Summary of the Invention

[0004] Purpose of the invention: To address the above-mentioned shortcomings, this invention provides an underground pipeline detection system based on directional source-well electromagnetic induction that offers high detection accuracy and is easy to operate.

[0005] The present invention also provides a method for detecting underground pipelines based on directional source-well electromagnetic induction.

[0006] Technical Solution: To solve the above problems, this invention employs an underground pipeline detection system based on directional source-well electromagnetic induction, comprising a magnetic field source module for exciting a ring-shaped magnetic field in the target pipeline, a vertically downward-facing well located on one side of the target pipeline, a measuring coil, a drive module for rotating the measuring coil and moving it along the well, a measuring module for obtaining the magnetic flux of the measuring coil, and a calculation module; the plane of the measuring coil forms an acute angle with the horizontal plane, the drive module drives the measuring coil to rotate around a vertical axis passing through the center of the measuring coil, the drive module drives the measuring coil to rotate to change the magnitude of the magnetic flux of the measuring coil, the drive module drives the measuring coil to rise and fall to change the position of the measuring coil, the measuring module also obtains the real-time depth of the measuring coil in the well and the rotation angle of the measuring coil, and the calculation module calculates the position of the target pipeline relative to the well based on the position of the measuring coil obtained by the measuring module and the corresponding magnetic flux at that position.

[0007] Furthermore, several wells are set up on one side of the target pipeline, and the drive module and measuring coil are sequentially set in the several wells. The calculation module calculates the direction and position of the target pipeline based on the data measured in the several wells.

[0008] Furthermore, a PVC pipe is installed in the well, the measuring coil is located inside the PVC pipe and moves along the PVC pipe, the depth of the PVC pipe is greater than 1.5 times the target pipeline depth, the inclination of the PVC pipe is less than 1%, and the bottom of the PVC pipe is sealed with a floor drain.

[0009] Furthermore, the drive module includes a drive gear base, a drive gear positioned on the drive gear base, and a rack rod meshing with the drive gear; the measuring coil is fixedly connected to the rack rod, the rack rod extends vertically and passes through the center of the measuring coil, and the drive gear base rotates relative to the drilling.

[0010] This invention also employs an underground pipeline detection method based on directional source-well electromagnetic induction, comprising the following steps:

[0011] (1) Obtain the approximate direction and depth of the target pipeline, and set up several vertically extending wells on one side of the target pipeline;

[0012] (2) Input current into the target pipeline to excite the target pipeline to generate a ring magnetic field;

[0013] (3) A measuring coil is lowered into one of the wells to obtain the depth and magnetic flux of the measuring coil in real time. The plane where the measuring coil is located forms an acute angle with the horizontal plane.

[0014] (4) When the magnetic flux changes by a factor of 1 m when the measuring coil descends to a depth of 1 m, stop lowering the coil and drive the measuring coil to rotate around the vertical axis passing through the center of the measuring coil to obtain the magnetic flux corresponding to the rotation angle and obtain the angle corresponding to the extreme value of the magnetic flux.

[0015] (5) Adjust the angle of the measuring coil when the magnetic flux is at its extreme value, and then lower the measuring coil;

[0016] (6) When the magnetic flux of the measuring coil reaches its maximum value and then decreases, obtain the measuring coil depth h corresponding to the maximum magnetic flux value. max1 And adjust the measuring coil to rotate 180°, and then lower the measuring coil;

[0017] (7) When the magnetic flux of the measuring coil reaches its maximum value again and then decreases, obtain the depth h of the measuring coil corresponding to the maximum magnetic flux value. max2 ;

[0018] (8) Based on depth h max1 and depth h max2 The position of the target pipeline relative to the wellbore was calculated;

[0019] (9) Repeat steps (3) to (8) for other wells to locate the target pipeline within the target range.

[0020] Furthermore, the formula for calculating the target pipeline location in step (8) is as follows:

[0021]

[0022]

[0023] Where h0 is the depth of the target pipeline; x is the horizontal distance of the target pipeline relative to the well; and γ is the fixed angle between the plane where the measuring coil is located and the horizontal plane.

[0024] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that it calculates the direction, depth and horizontal distance of the target underground pipeline relative to the well based on the electromagnetic induction characteristics in the well and the positional relationship between the target pipeline and the well. The calculated positional error is small, the acquisition cycle is short, the investment cost is low, the detection process is highly resistant to interference, and the detection results are accurate, which better meets the needs of actual detection. Attached Figure Description

[0025] Figure 1 The figure shown is a schematic diagram of the overall structure of the underground pipeline detection system of the present invention.

[0026] Figure 2 The diagram shown illustrates the principle of underground pipeline detection according to the present invention.

[0027] Figure 3 The diagram shows the variation of magnetic flux of the measuring coil with depth in this invention.

[0028] Figure 4 The diagram shown is a schematic of the drive module structure in this invention.

[0029] Figure 5 The diagram shown is a simplified representation of the driving principle of the driving module in this invention. Detailed Implementation

[0030] like Figures 1 to 3As shown in this embodiment, an underground pipeline detection system based on directional source-well electromagnetic induction includes a magnetic field source module for exciting a ring-shaped magnetic field in the target pipeline 1, a vertically downward drilling well 2 located on one side of the target pipeline 1, a drive module 3, a measuring probe, a measuring module, a real-time digital display module, and a calculation module. The target pipeline can be a steel pipe, cable, or cast iron pipe, etc. In this embodiment, the target pipeline is a cable. The approximate direction and location of the target pipeline can be determined based on relevant data of the target pipeline 1 or by using existing technology. Several wells are first drilled near the target pipeline 1, with a depth greater than 1.5 times the expected depth of the target pipeline. Each well is submerged to the same depth as a 125mm PVC water supply pipe, serving as a lifting channel for the measuring probe to ensure sufficient compressive strength and prevent deformation. The PVC pipe is sealed with a floor drain. The inclination of the drilling wells and the PVC pipes within the wells is less than 1%.

[0031] The magnetic field source module includes a transmitter 4 and a clamp 5 connected to the output end of the transmitter. At the exposed end of the target pipeline 1, the transmitter 4 outputs a specific frequency current to the clamp 5. The magnetic field generated by the clamp excites the target pipeline to generate a signal current, thereby generating a ring magnetic field centered on the target pipeline.

[0032] Drive module 3 is used for the vertical movement and 360° rotation of the measuring module in the PVC pipe inside the well; such as Figure 4 As shown, the drive module 3 includes several detachable and modular rack rods 31 and a hand-cranked rack lifting device. Each rack rod 31 is connected by four screws; the bottom rack rod 31 is fixedly connected to the middle of the top of the PVC pipe 7. The hand-cranked rack lifting device includes a fixed base 32 and a rotating platform 33. The fixed base 32 is fixedly installed at the top of the PVC pipe inside the drilling rig 2. The rotating platform 33 is positioned on the fixed base 32 and can rotate 360° relative to the fixed base 32. The drive gear 34 is set on the rotating platform 33 and is driven to rotate by the hand crank 35. The rack rods 31 are positioned on the rotating platform and mesh with the drive gear 34. The rotation of the rotating platform can simultaneously drive the rack and the measuring module to rotate.

[0033] The measurement module is used to obtain the magnetic flux of the measurement probe. The measurement probe includes a measurement coil 6 and a 110mm PVC pipe 7 with upper and lower sealing. The measurement coil 6 is a rectangular inductor coil, and the plane of the measurement coil 6 forms an acute angle with the horizontal plane. In this embodiment, the plane of the measurement coil 6 forms a 45° angle with the horizontal plane. The outer 110mm PVC pipe 7 serves for waterproofing and protection. A cable connects the measurement coil, the measurement module, and the real-time digital display device. The real-time display module 8 is used for real-time feedback of the magnetic flux measured by the in-well measurement module, allowing for rapid analysis and operation based on the feedback.

[0034] The calculation module determines the direction, depth, and horizontal distance of the target pipeline relative to the wellbore based on the location (depth) of the magnetic flux maxima. The measuring coil located in the wellbore exhibits maximum magnetic flux above the target pipeline depth when facing away from it, and maximum magnetic flux below the target pipeline depth when facing it. This is used to determine the direction of the target pipeline during measurement. The magnetic flux variation with depth when facing away from or towards the target pipeline shows a single peak with a unique maximum value. This is used to locate underground pipelines within the target area.

[0035] Example 2

[0036] This example illustrates an underground pipeline detection method based on directional source-well electromagnetic induction, comprising the following steps:

[0037] (1) Obtain the approximate direction and depth of the target pipeline, drill a well on one side of the target pipeline, set up several vertically extending wells, the well depth is about 1.5 times the burial depth of the target pipeline, and after the well is completed, sink a 125mm PVC water supply pipe of the same depth.

[0038] (2) Connect the measuring probe to the rack, set up the rack lifting device at the pipe opening, clamp the exposed end of the target pipeline, and start the transmitter;

[0039] (3) Lower a measuring coil into one of the boreholes. Based on the approximate direction of the pipeline, lower the coil according to δ = δ1, where δ1 is determined by the operator and should be as close to 0 as possible (i.e., facing away from the target pipeline). Angle δ represents the direction angle between the measuring coil and the target pipeline. δ = 0 means the measuring coil faces away from the pipeline, and δ = 180° means the measuring coil faces the pipeline. Facing away from and facing the target pipeline refers to the angle γ direction facing away from and facing the target pipeline, respectively. Slowly lower the measuring probe while simultaneously lowering the cable to obtain the depth and magnetic flux of the measuring coil in real time. The plane where the measuring coil is located forms an acute angle with the horizontal plane.

[0040] (4) When the measurement probe is lowered to a depth where the magnetic flux changes significantly, stop lowering the coil and drive the measurement coil to rotate around the vertical axis passing through the center of the measurement coil to change δ, obtain the magnetic flux corresponding to the rotation angle, and obtain the angle corresponding to the extreme value of the magnetic flux; set the angle corresponding to the extreme value of the magnetic flux at the current depth to δ = 0, and obtain the direction of the target pipeline according to the angle corresponding to the extreme value of the magnetic flux, and the magnetic flux has one and only one maximum value in the depth direction when the value of δ is constant;

[0041] (5) Adjust the angle of the measuring coil when the magnetic flux is at its extreme value, i.e., δ = 0, keep δ = 0, and continue to slowly lower the measuring probe;

[0042] (6) The maximum value is roughly measured by changing the depth at a relatively upper position in the well. Then, the probe is slowly raised and lowered near the maximum value to precisely lock the position of the maximum value. At this time, the probe depth is h. max1As you continue to lower the measuring probe, you will find that the magnetic flux gradually decreases. At this point, adjust the measuring coil to rotate 180°, i.e., δ = 180°, and then continue to lower the probe.

[0043] (7) The depth h of the maximum magnetic flux of the measuring coil is measured again through coarse and fine measurements. max2 ;

[0044] (8) According to h max1 h max2 The depth and horizontal distance of the target pipeline corresponding to the well are calculated by the calculation module. The calculation formula is as follows:

[0045]

[0046]

[0047] (9) Repeat steps (3) to (8) for other wells to locate underground pipelines within the target area.

[0048] The calculated positional error is small, which well meets the needs of actual detection.

Claims

1. An underground pipeline detection system based on directional source-well electromagnetic induction, characterized in that, The system includes a magnetic field source module for generating a ring-shaped magnetic field in the target pipeline, a vertically downward-facing drill bit positioned on one side of the target pipeline, a measuring coil, a drive module for rotating the measuring coil and moving it along the drill bit, a measuring module for obtaining the magnetic flux of the measuring coil, and a calculation module. The plane containing the measuring coil forms an acute angle with the horizontal plane. The drive module drives the measuring coil to rotate around a vertical axis passing through the center of the measuring coil. The drive module drives the measuring coil to rotate, changing the magnitude of the magnetic flux of the measuring coil. The drive module also drives the measuring coil to rise and fall, changing the position of the measuring coil. The measuring module also obtains the real-time depth of the measuring coil in the drill bit and the rotation angle of the measuring coil. The calculation module calculates the position of the target pipeline relative to the drill bit based on the position of the measuring coil obtained by the measuring module and the corresponding magnetic flux magnitude at that position.

2. The underground pipeline detection system according to claim 1, characterized in that, Several wells are set up on one side of the target pipeline. The drive module and the measuring coil are sequentially set in the several wells. The calculation module calculates the direction and position of the target pipeline based on the data measured in the several wells.

3. The underground pipeline detection system according to claim 1, characterized in that, A PVC pipe is installed in the well, and a measuring coil is located inside the PVC pipe and moves along the PVC pipe. The depth of the PVC pipe is greater than 1.5 times the target pipeline depth, the inclination of the PVC pipe is less than 1%, and the bottom of the PVC pipe is sealed with a floor drain.

4. The underground pipeline detection system according to claim 1, characterized in that, The drive module includes a drive gear base, a drive gear positioned on the drive gear base, and a rack rod meshing with the drive gear; the measuring coil is fixedly connected to the rack rod, the rack rod extends vertically and passes through the center of the measuring coil, and the drive gear base rotates relative to the drilling.

5. The underground pipeline detection system according to claim 1, characterized in that, The magnetic field source module includes a transmitter that outputs a current at a specific frequency and a clamp connected to the output end of the transmitter, with the clamp clamped at the end of the target pipeline.

6. The underground pipeline detection system according to claim 1, characterized in that, The measuring coil is a rectangular coil, and a PVC pipe is installed around the measuring coil.

7. A method for detecting underground pipelines based on directional source-well electromagnetic induction, characterized in that, Includes the following steps: (1) Obtain the approximate direction and depth of the target pipeline, and set up several vertically extending wells on one side of the target pipeline; (2) Input current into the target pipeline to excite the target pipeline to generate a ring magnetic field; (3) Lower a measuring coil into one of the wells and obtain the depth and magnetic flux of the measuring coil in real time. The plane where the measuring coil is located forms an acute angle with the horizontal plane. (4) When the magnetic flux changes by a factor of two when the measuring coil descends 1m, stop lowering the coil and drive the measuring coil to rotate around the vertical axis passing through the center of the measuring coil to obtain the magnetic flux corresponding to the rotation angle and obtain the angle corresponding to the extreme value of the magnetic flux. (5) Adjust the angle of the measuring coil when the magnetic flux is at its extreme value, and then lower the measuring coil; (6) When the magnetic flux of the measuring coil reaches its maximum value and then decreases, obtain the depth of the measuring coil corresponding to the maximum magnetic flux value. And adjust the measuring coil to rotate 180°, and then lower the measuring coil; (7) When the magnetic flux of the measuring coil reaches its maximum value again and then decreases, obtain the depth of the measuring coil corresponding to the maximum magnetic flux value. ; (8) Based on depth and depth The position of the target pipeline relative to the wellbore was calculated; (9) Repeat steps (3) to (8) for other wells to locate the target pipeline within the target range.

8. The method for detecting underground pipelines according to claim 7, characterized in that, The formula for calculating the target pipeline location in step (8) is as follows: ； ； in, The depth of the target pipeline; The horizontal distance between the target pipeline and the wellbore; This is to measure the fixed angle between the plane containing the coil and the horizontal plane.

9. The method for detecting underground pipelines according to claim 7, characterized in that, The fixed angle between the plane containing the measuring coil and the horizontal plane is 45°.

10. The underground pipeline detection method according to claim 7, characterized in that, A PVC pipe is installed in the well, and a measuring coil is located inside the PVC pipe and moves along the PVC pipe. The depth of the PVC pipe is greater than 1.5 times the target pipeline depth, the inclination of the PVC pipe is less than 1%, and the bottom of the PVC pipe is sealed with a floor drain.

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