A device and method for detecting underground metal pipelines based on permanent magnet magnetization field

Abstract

The invention discloses an underground metal pipeline detection device and method based on a permanent magnet magnetization field. The device and method obtain the distance between the center points of two three-axis magnetic field sensors and the upper surface of a permanent magnet, as well as the thickness of the permanent magnet and the height of its lower surface from the ground; in a non-detection area, the three-dimensional magnetic field information measured by the magnetic field sensor is used as reference information; in a detection area, the detection device is horizontally moved, and when the difference between the vertical components of the magnetic field measured by the two magnetic field sensors passes through zero, it is determined that the metal pipeline is directly below the position where the detection device is located, thereby determining the horizontal direction offset of the underground metal pipeline; the detection device is placed at the position where the difference between the vertical components of the magnetic field passes through zero, and the horizontal component of the magnetic field generated by the underground metal pipeline is calculated according to the magnetic field reference and the measurement information of the magnetic field sensor, and the buried depth of the underground metal pipeline is determined according to the relationship that the horizontal component of the magnetic field is inversely proportional to the square of the buried depth of the underground metal pipeline, thereby realizing rapid detection of the underground metal pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of underground pipeline detection, and in particular relates to an underground metal pipeline detection device and method based on a permanent magnet magnetization field. Background Art

[0002] Urban underground metal pipelines have been widely used in cable laying, gas transportation, and sewage discharge, and are important urban infrastructure. However, due to poor personnel management, inadequate consideration during construction, and data loss during the preservation of buried pipeline information, urban underground pipelines are often damaged by construction, threatening the safety of life and property. Therefore, it is necessary to quickly detect and locate buried metal pipelines, promptly identify the current status of underground pipelines, and provide important basic data for subsequent urban planning and construction management. Among them, high-precision positioning of underground metal pipelines by detecting ground magnetic field information in a trenchless manner has always been the focus and difficulty of underground pipeline detection.

[0003] In the related technology, the main method to solve the pipeline positioning is based on external excitation or geomagnetic field information detection: for example, an external sinusoidal alternating current excitation is used on the metal pipeline, and the conductivity and electromagnetic induction principle of the metal pipeline are used to detect the distribution of the excited magnetic field on the ground, so as to achieve the purpose of locating the metal pipeline. However, it is necessary to have an excavation point on the metal pipeline to apply external excitation, and it is impossible to detect underground trenchless pipelines. For another example, the uniformity of the geomagnetic field and the characteristics of the metal pipeline that can change the distribution of the geomagnetic field can be used to detect the inhomogeneity of the surface magnetic field, so as to judge the position of the underground metal pipeline and achieve the positioning purpose. However, the magnetic anomaly excited by the metal pipeline in the geomagnetic field is small, and the magnitude of the detected magnetic field is small, resulting in large detection errors and inaccurate positioning. Summary of the invention

[0004] The purpose of the present invention is to provide an underground metal pipeline detection device and method based on a permanent magnet magnetization field, so as to solve the problems of large detection error and inaccurate positioning of metal pipelines in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] An underground metal pipeline detection device based on a permanent magnet magnetization field, comprising:

[0007] A permanent magnet arranged on a horizontal plane is used to generate a static magnetic field required for underground metal pipeline detection;

[0008] A magnetic field sensor at point B and a magnetic field sensor at point A are sequentially arranged directly above the permanent magnet to detect current three-dimensional magnetic field information;

[0009] A signal transmission unit, connected to the magnetic field sensor at point B and the magnetic field sensor at point A, and configured to transmit the three-dimensional magnetic field information to a signal processing unit, a signal storage unit, and a signal display unit;

[0010] A signal processing unit, connected to the signal transmission unit, is used to analyze and process the acquired three-dimensional magnetic field information to detect the horizontal position and buried depth of underground metal pipelines;

[0011] A signal storage unit, connected to the signal processing unit, for storing the three-dimensional magnetic field information after signal processing and the horizontal position and buried depth of the underground metal pipeline;

[0012] The signal display unit is connected to the signal processing unit and is used to display the three-dimensional magnetic field information and the horizontal position and buried depth of the pipeline.

[0013] Furthermore, the magnetic field sensor at point B and the magnetic field sensor at point A are both three-axis magnetic field sensors; the magnetic field sensor at point B is located at point A above the permanent magnet, the magnetic field sensor at point A is located at point B above the permanent magnet, and point A is located above point B.

[0014] Furthermore, the three-dimensional magnetic field information includes:

[0015] When the underground metal pipeline detection device is located in the detection area without metal pipelines, the three-axis magnetic field component B obtained by the magnetic field sensor at point A x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B ;

[0016] When the underground metal pipeline detection device is located in the detection area with metal pipelines, the vertical component B' of the magnetic field obtained by the magnetic field sensor at point A z-A , and the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point B z-B ;

[0017] When the underground metal pipeline detection device is located at a position where the difference of the vertical component of the magnetic field is zero, the projection component B′ of the magnetic field component obtained by the magnetic field sensor at point A on the x-axis and y-axis x-A , B′ y-A , and the projection component B′ of the magnetic field component obtained by the magnetic field sensor at point B on the x-axis and y-axis x-B , B′ y-B .

[0018] Furthermore, the method in which the signal processing unit analyzes and processes the acquired three-dimensional magnetic field information is as follows:

[0019] According to B z-A , Bz-B , B′ z-A , B′ z-B , calculate the vertical component B″ of the magnetic field generated by underground metal pipelines z-A =B′ z-A -B z-A , B″ z-B =B′ z-B -B z-B ;

[0020] When the vertical component difference of the magnetic field is B″ z-A -B″ z-B When it crosses zero, it is determined that the metal pipeline is directly below the location of the underground metal pipeline detection device;

[0021] According to B x-A , B x-B , B y-A , B y-B , B′ x-A , B′ x-B , B′ y-A , B′ y-B , the horizontal component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h-A , B″ h-B ;

[0022] According to the distance r between the center points A and B of the three-axis magnetic field sensor and the upper surface of the permanent magnet 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1 , and B″ h-A , B″ h-B , using the inverse proportional relationship between the horizontal component of the magnetic field and the square of the pipeline burial depth, the depth of underground metal pipelines can be measured.

[0023] Furthermore, the horizontal component B″ of the magnetic field generated at points A and B when there is only an underground metal pipeline h-A , B″ h-B The calculation method is as follows:

[0024]

[0025] Among them, B′ x-A , B′ y-A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B′ x-B , B′ y-B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , By-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

[0026] Furthermore, the buried depth h of the underground metal pipeline is calculated as follows:

[0027]

[0028] Among them, r 1 、r 2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h is 1 is the height of the lower surface of the permanent magnet from the ground; B h ″ -A , B h ″ -B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

[0029] A method for detecting underground metal pipelines based on a permanent magnet magnetization field is implemented by the above-mentioned underground metal pipeline detection device, comprising the following steps:

[0030] S1: Get the distance r between the center points A and B of the magnetic field sensor at point B and the upper surface of the permanent magnet 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1 ;

[0031] S2: When the underground metal pipeline detection device is located in the detection area without metal pipelines, the three-axis magnetic field component B obtained by the magnetic field sensor at point A x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B ;

[0032] S3: Obtain the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point A when the underground metal pipeline detection device is located in the detection area with metal pipelines z-A and the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point B z-B ;

[0033] S4: According to B z-A , B z-B , B′ z-A , B′ z-B , obtain the vertical component B of the magnetic field generated at points A and B when there are only underground metal pipelines z ″ -A =B′ z-A -B z-A, B z ″ -B =B′ z-B -B z-B ;

[0034] S5: When the vertical component difference of the magnetic field between points A and B is B z ″ -A -B z ″ -B When it crosses zero, it is determined that the underground metal pipeline is directly below the location of the detection device;

[0035] S6: When the underground metal pipeline detection device is located at the position where the difference of the vertical component of the magnetic field passes through zero, the projection component B′ of the magnetic field information obtained by the magnetic field sensor at point A on the x-axis and y-axis is obtained. x-A , B′ y-A , and the projection component B′ of the magnetic field information obtained by the magnetic field sensor at point B on the x-axis and y-axis x-B , B′ y-B ;

[0036] S7: According to B x-A , B x-B , B y-A , B y-B , B′ x-A , B′ x-B , B′ y-A , B′ y-B , the horizontal component B of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h ″ -A and B h ″ -B ;

[0037] S8: According to the distance r between the center points A and B of the two magnetic field sensors and the upper surface of the permanent magnet 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1 , and the horizontal component B of the magnetic field generated at points A and B when there are only underground metal pipelines h ″ -A , B h ″ -B Based on the inverse proportionality between the horizontal component of the magnetic field and the square of the pipeline burial depth, the burial depth of the underground metal pipeline is measured.

[0038] Furthermore, the horizontal component B of the magnetic field generated at points A and B when there is only an underground metal pipeline h ″ -A , B h ″ -B The calculation method is as follows:

[0039]

[0040] Among them, B′ x-A , B′ y-A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B′ x-B , B′ y-B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , B y-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

[0041] Furthermore, the buried depth h of the underground metal pipeline is calculated as follows:

[0042]

[0043] Among them, r 1 、r 2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h is 1 is the height of the lower surface of the permanent magnet from the ground; B h ″ -A , B h ″ -B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

[0044] Furthermore, the line connecting the magnetic field sensor at point B, the magnetic field sensor at point A and the center point of the permanent magnet is a straight line perpendicular to the horizontal plane; the magnetic field sensor at point B and the magnetic field sensor at point A are on the same side of the permanent magnet, and the distance r between their center points and the upper surface of the permanent magnet is 1 、r 2 And the thickness d of the permanent magnet satisfies:

[0045] The beneficial effects of the present invention are as follows:

[0046] The present invention provides an underground metal pipeline detection method based on a permanent magnet magnetization field, which obtains the distance between the center points of two three-axis magnetic field sensors and the upper surface of a permanent magnet, as well as the thickness of the permanent magnet and the height of its lower surface from the ground; in a detection area without metal pipelines, the three-dimensional magnetic field information measured by the magnetic field sensor is used as reference information; in a detection area with metal pipelines, the detection device is horizontally moved, and when the difference of the vertical components of the magnetic field measured by the two magnetic field sensors passes through zero, it is determined and recorded that the underground metal pipeline is directly below the position of the detection device, thereby determining the horizontal direction offset of the underground metal pipeline; the detection device is placed at the zero-crossing position of the difference of the vertical components of the magnetic field, and the horizontal component of the magnetic field generated by the underground metal pipeline is calculated according to the magnetic field reference and the measurement information of the magnetic field sensor, and the buried depth of the underground metal pipeline is determined according to the relationship that the horizontal component of the magnetic field is inversely proportional to the square of the buried depth of the underground metal pipeline. The method can realize the rapid detection of underground metal pipelines and improve the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1 This is a flow chart of an underground metal pipeline detection method based on a permanent magnet magnetization field according to an embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of position parameters of two three-axis magnetic field sensors, permanent magnets and pipelines in an embodiment of the present invention;

[0050] Figure 3 is a diagram of the horizontal positioning result in an embodiment of the present invention, including a diagram showing the relationship between the vertical components of the magnetic field at points A and B and the position of the detection device;

[0051] Figure 4 This is a comparison diagram of the solution results of the horizontal component of the magnetic field of the underground pipeline at a depth of 1m in an embodiment of the present invention;

[0052] Figure 5 It is a schematic structural diagram of an underground metal pipeline detection device based on a permanent magnet magnetization field according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0054] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention.

[0055] Example 1

[0056] like Figure 2 and Figure 5 As shown, Embodiment 1 of the present invention provides an underground metal pipeline detection device based on a permanent magnet magnetization field, specifically comprising:

[0057] A permanent magnet arranged on a horizontal plane is used to generate a static magnetic field required for underground metal pipeline detection;

[0058] A magnetic field sensor at point B and a magnetic field sensor at point A are arranged in sequence above the permanent magnet to detect the current three-dimensional magnetic field information; when there is a metal pipeline underground, the metal pipeline generates a weak disturbance magnetic field;

[0059] A signal transmission unit, connected to the magnetic field sensor at point B and the magnetic field sensor at point A, and used to transmit three-dimensional magnetic field information to the signal processing unit, the signal storage unit, and the signal display unit;

[0060] A signal processing unit, connected to the signal transmission unit, is used to analyze and process the acquired three-dimensional magnetic field information to detect the horizontal position and buried depth of underground metal pipelines;

[0061] A signal storage unit, connected to the signal processing unit, for storing the three-dimensional magnetic field information after signal processing and the horizontal position and buried depth of the underground metal pipeline;

[0062] The signal display unit is connected to the signal processing unit and is used to display the three-dimensional magnetic field information and the horizontal position and buried depth of the pipeline.

[0063] Applied to the embodiment of the present invention, the magnetic field sensor at point B and the magnetic field sensor at point A are both three-axis magnetic field sensors; the magnetic field sensor at point B is located at point A above the permanent magnet, the magnetic field sensor at point A is located at point B above the permanent magnet, and point A is located above point B. The line connecting the center points of the magnetic field sensor at point B, the magnetic field sensor at point A, and the permanent magnet is a straight line perpendicular to the horizontal plane; the magnetic field sensor at point B and the magnetic field sensor at point A are on the same side of the permanent magnet, and the distance r between their center points and the upper surface of the permanent magnet is 1 、r 2 And the thickness d of the permanent magnet satisfies:

[0064] Applied to the embodiment of the present invention, the three-dimensional magnetic field information includes: when the underground metal pipeline detection device is located in the detection area without metal pipelines, the three-axis magnetic field component B obtained by the magnetic field sensor at point A x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B When the underground metal pipeline detection device is located in the detection area with metal pipelines, the vertical component B' of the magnetic field obtained by the magnetic field sensor at point A z-A , and the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point B z-B When the underground metal pipeline detection device is located at a position where the difference of the vertical component of the magnetic field is zero, the projection component B′ of the magnetic field component obtained by the magnetic field sensor at point A on the x-axis and y-axis x-A , B′ y-A , and the projection component B′ of the magnetic field component obtained by the magnetic field sensor at point B on the x-axis and y-axis x-B , B′ y-B .

[0065] Applied to the embodiment of the present invention, the method in which the signal processing unit analyzes and processes the acquired three-dimensional magnetic field information is as follows: z-A , B z-B , B′ z-A , B′ z-B , calculate the vertical component B″ of the magnetic field generated by underground metal pipelines z-A =B′ z-A -B z-A , B″ z-B =B′ z-B -B z-B When the vertical component difference of the magnetic field is B″ z-A -B″ z-B When it crosses zero, it is determined that the metal pipeline is directly below the location of the underground metal pipeline detection device. x-A , B x-B , B y-A , B y-B , B′ x-A , B′ x-B , B′ y-A , B′ y-B , the horizontal component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h-A , B″ h-B According to the distance r between the center points A and B of the three-axis magnetic field sensor and the upper surface of the permanent magnet 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1 , and B″ h-A, B″ h-B , using the inverse proportional relationship between the horizontal component of the magnetic field and the square of the pipeline burial depth, the depth of underground metal pipelines can be measured.

[0066] The horizontal component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines h-A , B″ h-B The calculation method is as follows:

[0067]

[0068] Among them, B′ x-A , B′ y-A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B′ x-B , B′ y-B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , B y-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

[0069] The calculation method of buried depth h of underground metal pipeline is as follows:

[0070]

[0071] Among them, r 1 、r 2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h is 1 is the height of the lower surface of the permanent magnet from the ground; B″ h-A , B″ h-B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

[0072] It should be noted that the magnetization direction of the permanent magnet is along the length direction and the length direction is parallel to the horizontal plane when the permanent magnet is placed. The magnetization direction, that is, the length direction of the permanent magnet is defined as the x-axis direction, the direction perpendicular to the x-axis and parallel to the horizontal plane is defined as the y-axis direction, and the direction perpendicular to the horizontal plane is defined as the z-axis direction. The coordinate system composed of the x, y, and z axes satisfies the right-hand rule.

[0073] The embodiment of the present invention is an underground metal pipeline detection device based on a permanent magnet magnetization field. The higher intensity magnetic field generated by the permanent magnet is used to detect the horizontal position of the detection device when the vertical component of the magnetic field passes through zero, thereby realizing the horizontal orientation of the underground pipeline position. The horizontal component generated by the underground metal pipeline is detected, and the relationship between the quadratic change of the magnetic field measured by the magnetic field sensor and the inverse proportion to the buried depth of the pipeline is solved to solve the buried depth of the metal pipeline, thereby solving the problem that the detection point needs to be excavated during pipeline detection and the amplitude of the detection signal is small.

[0074] Example 2

[0075] like Figure 1 As shown, a method for detecting underground metal pipelines based on a permanent magnet magnetization field is implemented by the underground metal pipeline detection device provided in Example 1, and includes the following steps:

[0076] S1: Get the distance r between the center points A and B of the magnetic field sensor at point B and the upper surface of the permanent magnet installed in the underground metal pipeline detection device 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1 .

[0077] In one example of the present invention, the distance r between the center points A and B of two three-axis magnetic field sensors installed in the underground metal pipeline detection device and the upper surface of the permanent magnet is obtained. 1 =17cm, r 2 =47cm and the thickness of the permanent magnet d = 3cm and the height of its lower surface from the ground h 1 =20cm.

[0078] S2: Place the underground metal pipeline detection device in the detection area without metal pipelines, and obtain the spatial distribution values ​​of the magnetic field at points A and B when the underground metal pipeline detection device is located in the detection area without metal pipelines. The spatial distribution values ​​of the magnetic field at points A and B include the three-axis magnetic field component B obtained by the magnetic field sensor at point A. x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B .

[0079] It should be noted that B x-A , B y-A , B z-A and B x-B , B y-B , B z-BThe magnetic field components should be measured in the detection area without metal pipelines. At this time, the detection area is the magnetic field calibration area. There must be no other permanent magnets, alternating magnetic fields, ferromagnetic materials and other factors that may cause changes in the magnetic field components.

[0080] S3: Place the underground metal pipeline detection device in the detection area with metal pipelines, and obtain the spatial distribution values ​​of the magnetic field at points A and B when the underground metal pipeline detection device is located in the detection area with metal pipelines. The spatial distribution values ​​of the magnetic field at points A and B include the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point A. z-A and the vertical component B′ of the magnetic field obtained by the magnetic field sensor at point B z-B .

[0081] It should be noted that when measuring in a detection area with metal pipelines, the placement height of the device and the spatial relative positions of the two three-axis magnetic field sensors and the permanent magnet should be consistent with those in a detection area without metal pipelines.

[0082] S4: The vertical component B of the magnetic field is obtained by measuring the two points A and B in the detection area without metal pipelines and the detection area with metal pipelines. z-A , B z-B , B′ z-A , B′ z-B , obtain the vertical component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines z-A =B′ z-A -B z-A , B″ z-B =B′ z-B -B z-B ;

[0083] S5: Horizontally move the underground metal pipeline detection device to observe the vertical component difference B″ of the magnetic field generated by the underground metal pipeline at points A and B z-A -B″ z-B When the difference between the vertical components of the magnetic field at points A and B is B″ z-A -B″ z-B When it passes through zero, the offset distance x, y of the position of the detection device in the horizontal plane is recorded to determine that the underground metal pipeline is directly below the position of the detection device.

[0084] Specifically, in the embodiment of the present invention, the vertical component of the magnetic field changes with the horizontal position as follows: Figure 3 As shown, the horizontal plane offset distance x of the position of the recording detection device is 1m, and y is 0m, and the actual horizontal plane offset distance x is 1m, and y is 0m. Therefore, there is no error in positioning in the horizontal direction in the embodiment of the present invention.

[0085] It should be noted that when the difference in the vertical component of the magnetic field generated by the underground metal pipeline passes through zero, it can be a positive zero crossing point, that is, the zero crossing point where the difference in the vertical component of the magnetic field changes from a positive value to a negative value, or it can be a reverse zero crossing point, that is, the zero crossing point where the difference in the vertical component of the magnetic field changes from a negative value to a positive value.

[0086] S6: Place the underground metal pipeline detection device at the position where the difference of the vertical component of the magnetic field crosses zero. When the underground metal pipeline detection device is located at the position where the difference of the vertical component of the magnetic field crosses zero, detect the distribution values ​​of the horizontal component of the magnetic field at points A and B through two three-axis magnetic field sensors. The distribution value of the horizontal component of the magnetic field includes the projection component B′ of the magnetic field information obtained by the magnetic field sensor at point A on the x-axis and y-axis. x-A , B′ y-A , and the projection component B′ of the magnetic field information obtained by the magnetic field sensor at point B on the x-axis and y-axis x-B , B′ y-B ;

[0087] S7: Projection component B of the magnetic field information on the x-axis and y-axis obtained from the measurement of points A and B in the detection area without metal pipelines and the detection area with metal pipelines x-A , B x-B , B y-A , B y-B , B′ x-A , B′ x-B , B′ y-A , B′ y-B , the horizontal component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h-A and B″ h-B ;

[0088]

[0089] Among them, B′ x-A , B′ y-A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B′ x-B , B′ y-B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , B y-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

[0090] S8: According to the distance r between the center points A and B of the two magnetic field sensors and the upper surface of the permanent magnet 1 、r 2 , as well as the thickness d of the permanent magnet and the height h of its lower surface from the ground 1, and the horizontal component B″ of the magnetic field generated at points A and B when there are only underground metal pipelines h-A , B″ h-B Based on the inverse proportionality between the horizontal component of the magnetic field and the square of the pipeline burial depth, the burial depth of the underground metal pipeline is measured.

[0091]

[0092] Among them, r 1 、r 2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h is 1 is the height of the lower surface of the permanent magnet from the ground; B″ h-A , B″ h-B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

[0093] For example, in the embodiment of the present invention, the relationship between the magnetic flux density and the buried depth of the underground pipeline is as follows: Figure 4 As shown, the measured buried depth h of the underground metal pipeline is 0.93m, the actual distance is 1m, and the positioning error in the vertical direction is less than 10cm.

[0094] It should be noted that the horizontal component of the magnetic field generated by the underground metal pipeline is inversely proportional to the square of the distance. The three-axis magnetic field sensor should be placed horizontally and the coordinate system of the three-axis magnetic field component should maintain a one-to-one correspondence with the actual x, y, and z three-axis coordinate system. The horizontal component of the magnetic field refers to the magnetic field component projected onto the horizontal plane, that is, the composite value of the x- and y-axis magnetic field components. The vertical component of the magnetic field refers to the magnetic field component projected onto a straight line perpendicular to the horizontal plane, that is, the z-axis magnetic field component.

[0095] The underground metal pipeline detection method based on permanent magnetic magnetization field provided in Example 2 of the present invention utilizes the higher intensity magnetic field generated by the permanent magnet to detect the horizontal position of the detection device when the vertical component of the magnetic field passes through zero, thereby realizing the horizontal orientation of the underground pipeline position; for the horizontal component detection generated by the underground metal pipeline, the magnetic field sensor is used to measure the quadratic change of the magnetic field, which is inversely proportional to the buried depth of the pipeline, and the buried depth of the metal pipeline is solved, thereby solving the problem of needing to excavate the detection point during pipeline detection and the small amplitude of the detection signal.

[0096] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. An underground metal pipeline detection device based on a permanent magnet magnetization field, characterized in that: include: A permanent magnet arranged on a horizontal plane is used to generate a static magnetic field required for underground metal pipeline detection; A magnetic field sensor at point B and a magnetic field sensor at point A are sequentially arranged directly above the permanent magnet to detect current three-dimensional magnetic field information; A signal transmission unit, connected to the magnetic field sensor at point B and the magnetic field sensor at point A, and configured to transmit the three-dimensional magnetic field information to a signal processing unit, a signal storage unit, and a signal display unit; A signal processing unit, connected to the signal transmission unit, is used to analyze and process the acquired three-dimensional magnetic field information to detect the horizontal position and buried depth of underground metal pipelines; A signal storage unit, connected to the signal processing unit, for storing the three-dimensional magnetic field information after signal processing and the horizontal position and buried depth of the underground metal pipeline; A signal display unit, connected to the signal processing unit, is used to display three-dimensional magnetic field information and the horizontal position and buried depth of the pipeline; The magnetic field sensor at point B and the magnetic field sensor at point A are both three-axis magnetic field sensors; the magnetic field sensor at point B is located at point A above the permanent magnet, the magnetic field sensor at point A is located at point B above the permanent magnet, and point A is located above point B; The three-dimensional magnetic field information includes: When the underground metal pipeline detection device is located in the detection area without metal pipelines, the three-axis magnetic field component B obtained by the magnetic field sensor at point A x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B ; When the underground metal pipeline detection device is located in the detection area with metal pipelines, the vertical component B of the magnetic field obtained by the magnetic field sensor at point A z ' -A , and the vertical component B of the magnetic field obtained by the magnetic field sensor at point B z ' -B ; When the underground metal pipeline detection device is located at a position where the difference of the vertical component of the magnetic field is zero, the projection component B of the magnetic field component obtained by the magnetic field sensor at point A on the x-axis and y-axis x ' -A , B y ' -A , and the projection components B of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis x ' -B , B y ' -B ; The method in which the signal processing unit analyzes and processes the acquired three-dimensional magnetic field information is as follows: According to B z-A , B z-B , B z ' -A , B z ' -B , calculate the vertical component B of the magnetic field generated by the underground metal pipeline z ″ -A =B z ' -A -B z-A , B z ″ -B =B z ' -B -B z-B ; When the vertical component difference of the magnetic field is B z ″ -A -B z ″ -B When it crosses zero, it is determined that the metal pipeline is directly below the location of the underground metal pipeline detection device; According to B x-A , B x-B , B y-A , B y-B , B x ' -A , B x ' -B , B y ' -A , B y ' -B , the horizontal component B of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h ″ -A , B h ″ -B ; According to the distance r1 and r2 between the center points A and B of the three-axis magnetic field sensor and the upper surface of the permanent magnet, the thickness d of the permanent magnet and the height h1 of its lower surface from the ground, and B h ″ -A , B h ″ -B , using the inverse proportional relationship between the horizontal component of the magnetic field and the square of the pipeline burial depth, the depth of underground metal pipelines can be measured.

2. The underground metal pipeline detection device based on permanent magnet magnetization field according to claim 1 is characterized in that: The horizontal component B of the magnetic field generated at points A and B when there is only an underground metal pipeline h ″ -A , B h ″ -B The calculation method is as follows: Among them, B x ' -A , B y ' -A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B x ' -B , B y ' -B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , B y-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

3. The underground metal pipeline detection device based on permanent magnet magnetization field according to claim 2 is characterized in that: The calculation method of the buried depth h of the underground metal pipeline is as follows: Among them, r1 and r2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h1 is the height of the lower surface of the permanent magnet from the ground; B h ″ -A , B h ″ -B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

4. A method for detecting underground metal pipelines based on a permanent magnet magnetization field, implemented by the underground metal pipeline detection device according to claim 1, characterized in that: The steps include: S1: Obtain the distances r1 and r2 between the center points A and B of the magnetic field sensor at point B and the magnetic field sensor at point A and the upper surface of the permanent magnet, as well as the thickness d of the permanent magnet and the height h1 of its lower surface from the ground; S2: When the underground metal pipeline detection device is located in the detection area without metal pipelines, the three-axis magnetic field component B obtained by the magnetic field sensor at point A x-A , B y-A , B z-A , and the three-axis magnetic field component B obtained by the magnetic field sensor at point B x-B , B y-B , B z-B ; S3: When the underground metal pipeline detection device is located in the detection area with metal pipelines, the vertical component B of the magnetic field obtained by the magnetic field sensor at point A z ' -A and the vertical component B of the magnetic field obtained by the magnetic field sensor at point B z ' -B ; S4: According to B z-A , B z-B , B z ' -A , B z ' -B , obtain the vertical component B of the magnetic field generated at points A and B when there are only underground metal pipelines z ″ -A =B z ' -A -B z-A , B z ″ -B =B z ' -B -B z-B ; S5: When the vertical component difference of the magnetic field between points A and B is B z ″ -A -B z ″ -B When it crosses zero, it is determined that the underground metal pipeline is directly below the location of the detection device; S6: When the underground metal pipeline detection device is located at the position where the difference of the vertical component of the magnetic field passes through zero, the projection component B of the magnetic field information obtained by the magnetic field sensor at point A on the x-axis and y-axis is obtained. x ' -A , B y ' -A , and the projection components B of the magnetic field information obtained by the magnetic field sensor at point B on the x-axis and y-axis x ' -B , B y ' -B ; S7: According to B x-A , B x-B , B y-A , B y-B , B x ' -A , B x ' -B , B y ' -A , B y ' -B , the horizontal component B of the magnetic field generated at points A and B when there are only underground metal pipelines is calculated h ″ -A and B h ″ -B ; S8: Based on the distances r1 and r2 between the center points A and B of the two magnetic field sensors and the upper surface of the permanent magnet, the thickness d of the permanent magnet and the height h1 of its lower surface from the ground, and the horizontal component B of the magnetic field generated at points A and B when there are only underground metal pipelines h ″ -A , B h ″ -B Based on the inverse proportionality between the horizontal component of the magnetic field and the square of the pipeline burial depth, the burial depth of the underground metal pipeline is measured.

5. The underground metal pipeline detection method based on permanent magnet magnetization field according to claim 4 is characterized in that: The horizontal component B of the magnetic field generated at points A and B when there is only an underground metal pipeline h ″ -A , B h ″ -B The calculation method is as follows: Among them, B x ' -A , B y ' -A are the projection components of the magnetic field components obtained by the magnetic field sensor at point A on the x-axis and y-axis respectively; B x ' -B , B y ' -B are the projection components of the magnetic field components obtained by the magnetic field sensor at point B on the x-axis and y-axis respectively; x-A , B y-A They are the three-axis magnetic field components obtained by the magnetic field sensor at point A; x-B , B y-B They are the three-axis magnetic field components obtained by the magnetic field sensor at point B.

6. The underground metal pipeline detection method based on permanent magnet magnetization field according to claim 4 is characterized in that: The calculation method of the buried depth h of the underground metal pipeline is as follows: Among them, r1 and r2 are the distances between the center points of the two magnetic field sensors A and B and the upper surface of the permanent magnet; d is the thickness of the permanent magnet; h1 is the height of the lower surface of the permanent magnet from the ground; B h ″ -A , B h ″ -B They are the horizontal components of the magnetic field generated at points A and B when there are only underground metal pipelines.

7. The underground metal pipeline detection method based on permanent magnet magnetization field according to claim 4 is characterized in that: The line connecting the center points of the magnetic field sensor at point B, the magnetic field sensor at point A and the permanent magnet is a straight line perpendicular to the horizontal plane; the magnetic field sensor at point B and the magnetic field sensor at point A are on the same side of the permanent magnet, and the distances r1 and r2 between their center points and the upper surface of the permanent magnet and the thickness d of the permanent magnet satisfy:

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