A buried pipeline depth positioning method based on magnetic anomaly characteristics of second degree body

Abstract

The application relates to a buried pipeline depth positioning method based on the characteristics of two-dimensional body magnetic anomaly, which uses a three-component magnetic sensor to measure, and can realize the determination of the depth of a buried pipeline on the premise of determining the pipeline azimuth angle. The buried pipeline is regarded as a two-dimensional body, the gradient value of the horizontal component magnetic anomaly curve of a single measuring line is obtained, the deviation rate is determined after the magnetic dip angle, the magnetic declination angle and the pipeline azimuth angle are calculated from the measurement data according to a preset pipeline buried depth value, then the distance between the maximum value and the minimum value of the gradient value of the magnetic anomaly of the single measuring line corresponding to the horizontal coordinate is obtained by the above method, and the actual pipeline buried depth value is calculated according to the deviation rate calculation formula. The method provided by the application fully utilizes the measurement data measured by the three-component magnetic sensor, the positioning result is more accurate, and the additional error caused by the polar conversion operation of other methods is overcome. The application overcomes the problem that the measuring line must be perpendicular to the pipeline axis direction when the pipeline buried depth is calculated by other methods, and the working efficiency is higher.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of positioning buried metal pipelines, and particularly relates to a buried pipeline depth positioning method based on magnetic anomaly characteristics of a two-dimensional body. BACKGROUND

[0002] If the exact spatial position of an existing pipeline cannot be accurately determined, the pipeline is easily damaged in the construction process, which may cause serious consequences. Magnetic detection belongs to passive detection, which is more convenient to operate than active detection, is not affected by weather factors, and does not require cleaning during measurement. With the development of magnetic measurement technology, from total field and its gradient to three-component measurement and then to full-tensor magnetic gradient measurement, the measured data is becoming richer and richer, and the methods for pipeline positioning are also emerging in an endless stream. The existing method based on a single total field sensor has the advantages that the measured data is a scalar, and is not sensitive to attitude transformation and vibration noise. However, the method has the disadvantages that the measured data is single, and it is necessary to increase the number of sensors or increase the number of measurement lines for multiple measurements to accurately position the target body. Compared with three-component magnetic measurement, full-tensor magnetic measurement requires higher installation precision of the magnetic sensor and has higher cost, and the detection depth is shallower. Therefore, the application is based on three-component magnetic measurement, but the existing method based on three-component magnetic measurement has the following disadvantages: prior information is required to ensure that the measurement line is perpendicular to the pipeline axis direction; and the magnetization pole operation is required, thereby introducing additional errors and affecting the positioning accuracy. SUMMARY

[0003] The application aims to solve the limitations of the prior art in positioning buried metal pipelines based on three-component magnetic measurement, in particular, the problems that the existing method requires prior information and the magnetization pole operation introduces additional errors, and provides a buried pipeline depth positioning method based on magnetic anomaly characteristics of a two-dimensional body.

[0004] The application is implemented in the following way,

[0005] A buried pipeline depth positioning method based on magnetic anomaly characteristics of a two-dimensional body, the method comprising:

[0006] The three-axis attitude angle transformation data of the measurement system is obtained by using an inertial navigation system for error correction of the three-component magnetic measurement data and conversion of the three-component magnetic measurement data to a geographic coordinate system;

[0007] The gradient value of the horizontal component of the three-component magnetic measurement data after error correction is calculated, and the horizontal coordinate position distance corresponding to the maximum gradient value and the minimum gradient value of the horizontal component is determined;

[0008] The magnetic inclination and the magnetic declination of the measuring position are obtained through the three-component magnetic measurement data, and the pipe azimuth angle of the buried pipeline and the geographic north is calculated through the position coordinates of the same magnetic anomaly data.

[0009] The deviation rate is obtained by substituting the magnetic inclination, the magnetic declination and the pipe azimuth angle into the magnetic anomaly forward model through the simulation of the magnetic anomaly data.

[0010] The actual pipe buried depth is obtained through the deviation rate.

[0011] Further, when the magnetic inclination is 90 degrees, the coordinate position distance corresponding to the maximum gradient value and the minimum gradient value of the horizontal component of the magnetic anomaly of the pipeline is the pipe buried depth.

[0012] Further, the magnetic inclination and the magnetic declination of the measuring position are obtained through the three-component magnetic measurement data, and the pipe azimuth angle of the buried pipeline and the geographic north is calculated through the position coordinates of the same magnetic anomaly data.

[0013] The magnetic inclination

[0014] The magnetic declination

[0015] B x is the component of the three-component magnetic measurement data in the x direction, B y is the component of the three-component magnetic measurement data in the y direction; and B z is the component of the three-component magnetic measurement data in the z direction.

[0016] Further, before measurement, the geographic north direction is determined, then two measuring lines perpendicular to the geographic north direction are measured, and the magnetic anomaly peak point coordinates are recorded.

[0017] According to the pipe azimuth angle is obtained. x and x0 are east position coordinates, y and y0 are north position coordinates, and x0 and y0 are position coordinates of the maximum value point of the magnetic anomaly curve.

[0018] Further, the pipe buried depth is obtained through the deviation rate, and the deviation rate δ calculation formula is:

[0019] wherein, l is the position distance of the horizontal component of the gradient maximum value and the gradient minimum value, and H is the pipe buried depth.

[0020] Further, the gradient is obtained by interpolating the magnetic anomaly horizontal component data into equal interval data, and the gradient value of the magnetic anomaly horizontal component data is obtained through difference.

[0021] Further, the deviation rate of the position distance and the preset pipe buried depth is calculated according to the magnetic inclination, the magnetic declination and the pipe azimuth angle, and the deviation rate δ calculation formula is:

[0022] According to the magnetic inclination, the magnetic declination, the pipeline azimuth angle, the magnetic anomaly forward model is substituted, the magnetic anomaly horizontal component data is simulated according to the magnetic anomaly forward model, the gradient value of the magnetic anomaly horizontal component data is obtained through difference, and the position distance of the horizontal component gradient maximum value and the horizontal component gradient minimum value is obtained according to the gradient value of the magnetic anomaly horizontal component data.

[0023] The deviation rate is calculated according to the position distance and the preset pipeline buried depth.

[0024] Compared with the prior art, the buried pipeline depth positioning method has the beneficial effects that:

[0025] Compared with the traditional method, the buried pipeline depth positioning method does not need prior information, and can calculate the buried pipeline depth only by two measuring lines, so that the working efficiency is greatly improved.

[0026] Compared with the traditional positioning algorithm, the buried pipeline depth positioning method does not need to be magnetized, avoids the additional error caused by magnetization, and improves the positioning accuracy. DETAILED DESCRIPTION

[0027] Figure 1 The buried pipeline azimuth angle calculation principle schematic diagram provided for the embodiment of the application is shown in the figure.

[0028] Figure 2 The buried pipeline depth positioning method principle schematic diagram provided for the embodiment of the application is shown in the figure.

[0029] Figure 3 The position distance schematic diagram provided for the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0031] A buried pipeline depth positioning method based on the magnetic anomaly characteristics of a two-degree body, the method comprising:

[0032] The three-axis attitude angle transformation data of the measurement system is obtained by using the inertial navigation system, which is used for error correction of the three-component magnetic measurement data and conversion of the three-component magnetic measurement data to the geographic coordinate system;

[0033] The gradient value of the horizontal component of the three-component magnetic measurement data after error correction is calculated, and the position distance of the horizontal component gradient maximum value and the horizontal component gradient minimum value is determined.

[0034] The magnetic inclination and the magnetic declination of the measuring position are obtained through three-component magnetic measurement data, and the pipe azimuth angle of the buried pipeline and the geographic north is calculated through the position coordinates of the same magnetic anomaly data;

[0035] The deviation rate is obtained through the simulation of the magnetic anomaly data by substituting the magnetic inclination, the magnetic declination and the pipe azimuth angle into the magnetic anomaly forward model;

[0036] The actual pipeline buried depth is inversely deduced through the deviation rate.

[0037] The method calculates the azimuth angle of the buried pipeline and the geographic north through the position coordinates of the same magnetic anomaly data, and determines the deviation rate of the position distance and the actual pipeline buried depth under different magnetic inclination, magnetic declination and pipe azimuth angle through theoretical calculation. The deviation rate is the ratio of the deviation and the actual buried depth, which is consistent under different pipeline buried depth, same magnetic inclination, magnetic declination and pipe azimuth angle. Therefore, after the magnetic inclination, the magnetic declination and the pipe azimuth angle are calculated through the measurement data, the deviation rate is calculated through the simulation of the magnetic anomaly and the preset pipeline buried depth, and then the actual pipeline buried depth is inversely deduced through the simulation calculated deviation rate. The application utilizes that when the magnetic inclination is 90 degrees, the coordinate position distance corresponding to the maximum gradient value and the minimum gradient value of the horizontal component of the magnetic anomaly of the two-dimensional pipeline is the pipeline buried depth, and when the magnetic inclination is not 90 degrees, the pipeline buried depth value can be inversely deduced through the preset pipeline buried depth value and the calculated deviation rate after the magnetic inclination, the magnetic declination and the pipe azimuth angle are calculated. After the pipe azimuth angle is determined, the pipeline buried depth can be accurately positioned through the data of a single measuring line, the detection efficiency is greatly improved, and the additional error introduced by the magnetization pole is avoided, and the positioning accuracy is improved.

[0038] The specific implementation process of the application comprises:

[0039] S1, a three-component magnetometer, an inertial navigation system and a magnetic attitude data synchronous acquisition device are provided for the magnetic measurement system. The three-component magnetometer and the inertial navigation system are installed on a non-magnetic platform to collect data. The collected attitude data and magnetic anomaly data are error corrected by using the acquisition system, and the magnetic measurement data are converted to the geographic coordinate system.

[0040] S2, the magnetic inclination and the magnetic declination are calculated according to the three-component magnetic measurement data.

[0041] Magnetic inclination

[0042] Magnetic declination

[0043] S3. The pipe azimuth angle is calculated. After the geographic north direction is determined, two measuring lines perpendicular to the geographic north direction are measured, and the magnetic anomaly peak point coordinates are recorded.

[0044] According to The pipe azimuth angle is obtained, refer to Figure 1 as shown.

[0045] S4. The inclination, declination and pipe azimuth angle are substituted into the pipe magnetic anomaly forward model to obtain the deviation rate. The deviation rate refers to the ratio of the deviation of the position distance to the actual buried depth to the actual buried depth. In the pipe magnetic anomaly forward model, the pipe coordinate system is established with the center point of the buried pipeline as the coordinate origin, the magnetic anomaly generated by the pipeline is calculated from the Poisson formula of the gravity and magnetic potential field. When the pipeline buried depth H is equal to the position y of the measuring line, the gradient value of the horizontal component is the maximum at this time. Based on this principle, the pipeline buried depth can be determined. The general case of the inclination not being 90 degrees is considered, and the influence of the pipe azimuth angle is considered. The angle between the pipe and the geographic north direction is defined as the pipe azimuth angle. The magnetic anomaly generated in the pipe coordinate system is converted to the geographic coordinate system through a rotation matrix, the position distance of the horizontal component maximum gradient value and the minimum gradient value corresponding to the transverse coordinate under different inclination, declination and pipe azimuth angle is calculated, and it is found that under the condition of the same inclination, declination and pipe azimuth angle, the deviation rate is consistent under different buried depths. Therefore, the deviation rate can be calculated by presetting the pipeline buried depth value, and the deviation rate calculation formula is:

[0046]

[0047] l is the position distance of the horizontal component gradient curve maximum value and the minimum value corresponding to the transverse coordinate, and H is the pipeline buried depth.

[0048] Among them, the magnetic anomaly horizontal component data is interpolated into equal interval data, and the gradient value of the magnetic anomaly horizontal component data is obtained by difference. The position coordinates corresponding to the maximum value of the magnetic gradient data curve and the position coordinates corresponding to the minimum value are distance.

[0049] In the present application, the pipe magnetic anomaly forward model. The pipe coordinate system is established with the center point of the buried pipeline as the coordinate origin, and the magnetic anomaly generated by the pipeline is calculated from the Poisson formula of the gravity and magnetic potential field. The gravitational potential of a volume v, uniform density object is:

[0050]

[0051] G is the gravitational constant, ρ is the density, and r is the distance between the observation point and the object.

[0052] The magnetic potential of the same uniform magnetized object is:

[0053]

[0054] M is the magnetization intensity vector.

[0055] T is the geomagnetic field, κ is the pipe magnetization, μ0 is the vacuum permeability.

[0056] The gravitational potential formula is substituted into the magnetic potential formula to obtain:

[0057]

[0058] By The magnetic field is calculated, where μ0 is the vacuum permeability.

[0059] The three-component magnetic field expression is calculated as follows:

[0060]

[0061] H ax represents the horizontal x-direction component of the magnetic anomaly, represents the horizontal y-direction component, and Z a represents the vertical component of the magnetic anomaly, V xx represents the partial derivative of the gravitational potential V in the x-direction in the x-direction, V yx represents the partial derivative of the gravitational potential V in the y-direction in the x-direction, V zx represents the partial derivative of the gravitational potential V in the z-direction in the x-direction;

[0062] where

[0063] I is the magnetic inclination, and D is the geomagnetic declination.

[0064] For a two-dimensional body, i.e., an object with infinite length along the strike, the burial depth, cross-sectional shape, and magnetization characteristics are stable along the horizontal strike. In this case, the field in the spatial rectangular coordinate system is only related to the coordinates (y, z) and is independent of x, where the x-direction is consistent with the pipe strike direction. The three-component magnetic field expression becomes:

[0065]

[0066] The gravitational potential expression of the horizontal cylinder is:

[0067] V = -2GρSlnr

[0068] S is the pipe cross-sectional area, x, y, z are the observation plane coordinates, and x0, y0, z0 are the pipe plane coordinates.

[0069] After taking the second-order partial derivative of the gravitational potential expression of the horizontal cylinder, substitute it into the three-component magnetic anomaly expression of the two-dimensional body:

[0070]

[0071] H is the preset pipe burial depth.

[0072] When the magnetic inclination is 90 degrees, the horizontal component H

[0073]

[0074] It can be seen that when the pipeline buried depth H is equal to the survey line position y, the horizontal component H ay has the maximum gradient value. Based on this principle, the pipeline buried depth can be determined. The principle is shown in the schematic diagram of Figure 2 . Considering the general case when the magnetic inclination is not 90 degrees, and considering the influence of the pipeline azimuth angle. Define the angle between the pipeline and the geographic north direction as the pipeline azimuth angle. Establish a geographic coordinate system, convert the magnetic anomaly generated in the pipeline coordinate system to the geographic coordinate system through a rotation matrix, calculate the position distance of the horizontal component maximum gradient value and the minimum gradient value corresponding to the horizontal coordinate under different magnetic inclination, magnetic declination and pipeline azimuth angle. It is found that under the condition of different buried depths, the same magnetic inclination, magnetic declination and pipeline azimuth angle, the deviation rate is consistent. Therefore, after calculating the magnetic inclination, magnetic declination and pipeline azimuth angle from the measured data, the pipeline buried depth value can be calculated by the above pipeline magnetic anomaly forward model to calculate the deviation rate. The deviation rate calculation formula is:

[0075]

[0076] According to the measured three-component magnetic survey data, the magnetic anomaly horizontal component data is interpolated into equal interval data, and the gradient value of the magnetic anomaly horizontal component data is obtained by difference.

[0077] According to the measured three-component magnetic survey data, the position distance of the horizontal component gradient curve maximum value and the minimum value corresponding to the horizontal coordinate is obtained, as shown in Figure 3 . The pipeline buried depth value H is obtained by the deviation rate calculation formula.

[0078] The above only describes the preferred embodiments of the present application and does not limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A buried pipeline depth positioning method based on the characteristics of the second-order magnetic anomaly, characterized in that, The method comprises: Obtaining the three-axis attitude angle transformation data of the measurement system by using the inertial navigation system for error correction of the three-component magnetic measurement data and conversion of the three-component magnetic measurement data to the geographic coordinate system; Calculating the gradient value of the horizontal component of the three-component magnetic measurement data after error correction, determining the horizontal component gradient maximum value and the horizontal component gradient minimum value corresponding to the horizontal coordinate position distance; Obtaining the magnetic inclination and the magnetic declination of the measurement site by using the three-component magnetic measurement data, and calculating the pipe azimuth angle of the buried pipeline and the geographic north by using the position coordinates of the same magnetic anomaly data; Substituting the magnetic inclination, the magnetic declination and the pipe azimuth angle into the magnetic anomaly forward model to obtain the deviation rate by simulating the magnetic anomaly data, including: simulating the magnetic anomaly horizontal component data according to the magnetic anomaly forward model, obtaining the gradient value of the magnetic anomaly horizontal component data by difference, and obtaining the horizontal component gradient maximum value and the horizontal component gradient minimum value corresponding to the horizontal coordinate position distance according to the gradient value of the magnetic anomaly horizontal component data; Calculating the deviation rate according to the position distance and the preset pipeline burial depth; The deviation rate refers to the ratio of the position distance to the pipeline burial depth; According to the position distance corresponding to the maximum value and the minimum value of the horizontal component gradient curve obtained by the measured three-component magnetic measurement data, the actual pipeline burial depth is obtained by backstepping the deviation rate.

2. The buried pipeline depth positioning method based on the magnetic anomaly characteristics of the two-dimensional body according to claim 1, wherein When the magnetic inclination is 90 degrees, the coordinate position distance corresponding to the maximum gradient value and the minimum gradient value of the magnetic anomaly horizontal component of the pipeline is the pipeline burial depth.

3. The buried pipeline depth positioning method based on the magnetic anomaly characteristics of the two-dimensional body according to claim 1, wherein Obtaining the magnetic inclination and the magnetic declination of the measurement site by using the three-component magnetic measurement data comprises: Magnetic dip angle , Magnetic inclination: , is a component of the direction of the magnetic field, is a component of the direction of the magnetic field, is a component of the direction of the magnetic field, is a component of the direction of the magnetic field. is a component of the direction of the magnetic field, is a component of the direction of the magnetic field.

4. The buried pipeline depth positioning method based on the magnetic anomaly characteristics of the two-dimensional body according to claim 1, wherein Before measurement, the geographic north direction is determined, two measurement lines perpendicular to the geographic north direction are measured, and the magnetic anomaly peak point coordinates are recorded. According to the pipe azimuth angle, is the east position coordinate, is the north position coordinate, is the position coordinate of the maximum point of the magnetic anomaly curve.

5. The buried pipeline depth positioning method based on the magnetic anomaly characteristics of the two-dimensional body according to claim 1, wherein The pipe depth is obtained by the deviation rate, and the deviation rate The calculation formula is: wherein, is the distance between the positions of the horizontal components of the maximum and minimum of the gradient of the gradient maximum and the gradient minimum, is the pipe depth.

6. The buried pipeline depth positioning method based on the magnetic anomaly characteristics of the two-dimensional body according to claim 1, wherein The gradient is obtained by interpolating the magnetic anomaly horizontal component data into equal interval data, and obtaining the gradient value of the magnetic anomaly horizontal component data by difference.

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