CN-122018017-A - Method and system for positioning buried pipeline based on magnetic gradient value

CN122018017ACN 122018017 ACN122018017 ACN 122018017ACN-122018017-A

Abstract

The invention discloses a method and a system for positioning a buried pipeline based on a magnetic gradient value, and belongs to the technical field of underground pipeline detection. The method comprises the steps of calculating an effective magnetization dip angle, obtaining an observation curve of a vertical magnetic gradient sequence in a single-hole measuring well adjacent to a target pipeline, extracting an extreme point depth value and calculating an extreme distance, calculating a horizontal transverse distance absolute value between the target pipeline and the single-hole measuring well, generating a theoretical curve according to the absolute value and a preset initial depth, comparing the theoretical curve with morphological characteristics of the observation curve, judging a horizontal azimuth and determining a horizontal transverse distance positive sign and a horizontal transverse distance negative sign, and finally inverting and calculating the accurate burial depth of the target pipeline according to the signed horizontal transverse distance, the extreme point depth value and dimensionless parameters. The invention can directly analyze the spatial position parameters of the pipeline by only single-hole data, effectively overcomes inversion multi-solution property, obviously reduces engineering cost and improves detection precision.

Inventors

ZHOU LEI
LIU HANG
DAI ZHIXIONG
Han Tianqing
GAO PENGFEI
ZHU JIANWEI
HU NAN
ZHANG XIAOXI
MA HAOSEN
LI YUNFEI
SHAO WENXUAN
WANG YARONG
ZHAO YUXIANG
XU HANYU
WANG ZILIN
BAI YUNKAI
CUI LINLIN
JIANG JUNHUA
Zheng Erlong
LI MUHAN
WANG PENG

Assignees

天津市测绘院有限公司

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (9)

1. A method for positioning a buried pipeline based on magnetic gradient values is characterized by comprising the following steps, 1) Acquiring geomagnetic field parameters of a construction area and a horizontal azimuth angle of a target pipeline preboring, and calculating an effective magnetization inclination angle of the target pipeline in a radial plane of vertical trend; 2) The extreme value distance calculation comprises the steps of collecting a vertical magnetic gradient sequence in a single-hole measuring well adjacent to a target pipeline, forming an observation curve, extracting a depth value corresponding to an extreme value from the observation curve, and calculating the extreme value distance; 3) Solving the absolute value of the horizontal transverse distance, namely constructing a theoretical relation based on a preset pipeline magnetic field model and combining the effective magnetization inclination angle and the extremum distance, and obtaining the absolute value of the horizontal transverse distance between the target pipeline and the single-hole measuring well; 4) Generating a theoretical curve of the vertical magnetic gradient according to the absolute value of the horizontal transverse distance and a preset initial depth, and comparing the morphological characteristics of the observed curve and the theoretical curve between extreme values, wherein if the observed curve and the theoretical curve are consistent, the horizontal transverse distance between the position of the target pipeline and the drilled hole is not negative, otherwise, the horizontal transverse distance is negative; 5) And (3) inverting the buried depth, namely inverting and calculating the accurate buried depth of the target pipeline according to the horizontal transverse distance with positive and negative signs, the depth value corresponding to the extreme value and the effective magnetization dip angle.
2. The method for positioning a buried pipeline based on magnetic gradient values according to claim 1, In order to effectively magnetize the tilt angle, , wherein, For a preboring horizontal azimuth of the target line, Is the magnetic dip angle of the geomagnetic field, Is the magnetic declination; Is a horizontal transverse distance, the horizontal transverse distance is equal to the horizontal transverse distance, ; For the distance between the extreme values, Z 1 、z 2 is the depth value corresponding to the extreme value, and z 1 >z 2 calculates the burial depth of the target pipeline The inversion formula of (c) is given by, , , ; Is a dimensionless parameter.
3. A method of locating a buried pipeline based on magnetic gradient values as set forth in claim 2, wherein a theoretical curve of vertical magnetic gradient is generated The calculation formula of (a) is as follows, , Is a horizontal transverse distance, the horizontal transverse distance is equal to the horizontal transverse distance, , For the relative depth of the two layers, , 、 For the horizontal coordinate value and depth value of the target pipeline center, In order to effectively magnetize the tilt angle, Is the effective magnetic moment per unit length, For the horizontal coordinate values and depth values of the probe, Is vacuum magnetic permeability.
4. A method of locating a buried pipeline based on magnetic gradient values as set forth in claim 1, wherein said step of consistency comparison of morphological features includes: Respectively extracting extreme values of an observation curve and a theoretical curve and corresponding depth values, and respectively calculating curve extreme value ratios by corresponding gradient values; respectively calculating point-by-point sequential mark parameters of the observation curve and the theoretical curve between extreme values, and compressing the form of the whole curve into a global sequential mark by analyzing the change rule of the point-by-point sequential mark parameter symbols in the sounding sequence; if the curve extremum ratio of the observed curve and the theoretical curve is in the same value range and the global sequence marks are equal, the morphological characteristics are considered to be consistent, otherwise, the morphological characteristics are not consistent.
5. A method of locating a buried pipeline based on magnetic gradient values as set forth in claim 4 wherein the global sequence flag is set to a mutually exclusive value of two symbols according to the order of occurrence of the extremum in the depth-wise direction.
6. A method of locating a buried pipeline based on magnetic gradient values as set forth in claim 1, wherein said step of acquiring a sequence of vertical magnetic gradients in step 2) includes: on-site preboring target line trend, obtaining estimated burial depth of target line Drilling a single-hole measuring well at the plane projection mark; the diameter of the well hole of the single-hole measuring well is not less than 8cm, and the drilling depth is not less than 1.5 ; And (3) the magnetic gradiometer probe is lowered to the bottom of the well at a constant speed, and the vertical component magnetic induction intensity and depth data are synchronously collected, wherein the sampling interval is not more than 0.05m.
7. The method for positioning a buried pipeline based on magnetic gradient values as set forth in claim 1, wherein said step 1) of obtaining information includes: Acquiring a geomagnetic field dip angle I and a magnetic declination angle D based on an international geomagnetic reference field model or local geomagnetic station data; adopting a metal pipeline detector to perform on-site investigation to preliminarily find out the approximate trend and the burial depth of the target pipeline and obtain the preboring horizontal azimuth angle 。
8. A method of locating a buried pipeline based on magnetic gradient values as set forth in claim 3, characterized in that the theoretical curve In the formula Taking an estimated depth of burial of a survey Or 10m.
9. A system for implementing a magnetic gradient value-based buried pipeline positioning method as set forth in any one of claims 1 to 8, comprising, The information acquisition module is used for acquiring geomagnetic field parameters of a construction area and a horizontal azimuth angle of the target pipeline preboring, and calculating an effective magnetization inclination angle of the target pipeline in a vertical trend radial plane; The extremum distance calculating module is used for collecting a vertical magnetic gradient sequence in a single-hole measuring well adjacent to a target pipeline and forming an observation curve, extracting a depth value corresponding to an extremum from the observation curve, and calculating an extremum distance; the horizontal transverse distance absolute value solving module is used for constructing a theoretical relation by combining the effective magnetization inclination angle and the extremum distance based on a preset pipeline magnetic field model and obtaining a horizontal transverse distance absolute value between a target pipeline and a single-hole measuring well; The horizontal azimuth sign determining module is used for generating a theoretical curve of a vertical magnetic gradient according to the absolute value of the horizontal transverse distance and a preset initial depth, and comparing the morphological characteristics of the observed curve and the theoretical curve between extreme values, if the observed curve and the theoretical curve are consistent, the horizontal transverse distance between the position of the target pipeline and the drilled hole is not negative, otherwise, the horizontal transverse distance is negative; The embedded depth inversion module is used for inverting and calculating the accurate embedded depth of the target pipeline according to the horizontal transverse distance with positive and negative signs, the depth value corresponding to the extreme value and the effective magnetization dip angle.

Description

Method and system for positioning buried pipeline based on magnetic gradient value Technical Field The invention belongs to the technical field of geophysical exploration and underground pipeline detection, and particularly relates to a buried pipeline positioning method and system based on magnetic gradient values. Background The in-well magnetic gradient method is an important means for detecting the deeply buried metal pipeline, and for the underground pipeline with metal substances with larger buried depth, the conventional electromagnetic induction method cannot meet the detection requirement, and the in-well detection technology effectively shortens the signal propagation path and remarkably improves the acquisition quality of deep signals by directly placing the receiving device into the well. The receiver collects signals at high frequency in the process of gradually sinking along the well to generate a signal depth profile excited by the target pipeline, the magnetic field strength of the signal depth profile is theoretically uniform in a soil layer without ferromagnetic substances, if ferromagnetic substances exist in the signal depth profile, an abnormal magnetic field is formed around the target pipeline under the magnetization effect of a background geomagnetic field, and a obvious acceleration change interval is displayed along with the change of the distance between a probe and the pipeline, so that the spatial position of the target pipeline can be judged by observing the change of magnetic abnormality, particularly the distribution of gradient values of vertical components. The current domestic data post-processing tool of the deep buried pipeline detection instrument based on the magnetic gradient characteristic value in the well is relatively simple, the pipeline position and the buried depth are calculated and judged manually through curves, and then the horizontal projection position of the target pipeline is gradually approximated by drilling until the drilling position can collide with the target pipeline. Chinese patent CN108241174a discloses a method for detecting a deeply buried metal pipeline, which comprises the steps of collecting original design and construction data, arranging a plurality of sections perpendicular to the direction of the pipeline in the pipeline estimation range, arranging 5-8 holes perpendicular to the direction of the pipeline in the detection section, measuring hole positions and hole openings elevation of all holes, placing a probe of a magnetic gradiometer into a sleeve, initially detecting the holes by using a magnetic gradient method, arranging two to three accurate drilling holes on the pipeline section, guiding the drill rod to descend by gravity until the drill rod is completely contacted with the surface of the pipeline, and accurately measuring the burial depth of the pipeline contact point by measuring the length of the drill rod. The detection method has the advantages of lower scientific measurement precision, higher requirement on the condition of a working face, lower safety when the target pipeline is a high-risk pipeline, lower efficiency of the successive approximation method, lower cost controllability and higher dependence on manual judgment. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a buried pipeline accurate positioning method based on a single Kong Chui-direction magnetic gradient characteristic value. The method introduces an effective magnetization dip angle calculation method by improving the detection flow, and directly analyzes the burial depth of the target pipeline and the transverse distance and absolute position relation between the burial depth and the drilled hole by utilizing the extremum characteristic value extracted from the single-hole gradient curve. In order to achieve the technical purpose, the invention adopts the following technical scheme: a method for locating buried pipeline based on magnetic gradient value includes such steps as, 1) Acquiring geomagnetic field parameters of a construction area and a horizontal azimuth angle of a target pipeline preboring, and calculating an effective magnetization inclination angle of the target pipeline in a radial plane of vertical trend; 2) The extreme value distance calculation comprises the steps of collecting a vertical magnetic gradient sequence in a single-hole measuring well adjacent to a target pipeline, forming an observation curve, extracting a depth value corresponding to an extreme value from the observation curve, and calculating the extreme value distance; 3) Solving the absolute value of the horizontal transverse distance, namely constructing a theoretical relation based on a preset pipeline magnetic field model and combining the effective magnetization inclination angle and the extremum distance, and obtaining the absolute value of the horizontal transverse distance between the target pipeline and the sing