A rapid location method for dam leakage channels based on total magnetic field gradient measurement

Abstract

The present invention discloses a method for quickly locating a dam leakage channel based on total magnetic field gradient measurement, which belongs to the field of water conservancy and engineering geophysical prospecting. The method comprises: laying out power supply electrodes and establishing a current loop; designing a gradient observation device, and using the gradient observation device to observe the magnetic field components generated by the current channel; laying out an observation profile in the direction perpendicular to the leakage channel, and using the gradient observation device to perform three-component magnetic anomaly observation; using the observed three-component magnetic anomaly values ​​to calculate the total magnetic field anomaly values ​​at different observation heights, and calibrate the lateral position of the leakage channel; and calculating the longitudinal buried depth of the leakage channel based on the total magnetic field anomaly values ​​at different observation heights corresponding to the lateral position of the leakage channel. The present invention utilizes the characteristic that the total magnetic field intensity generated by the leakage channel under artificial source excitation is inversely proportional to the distance, calculates the buried depth of the leakage channel, locates the leakage channel, and combines the located leakage channel with the leakage outlet on the back water surface to find the water inlet of the leakage channel.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and engineering geophysical prospecting, and in particular to a method for quickly locating a leakage channel of a dam based on total magnetic field gradient measurement. Background Art

[0002] Some embankments are ageing and face numerous and complex hidden dangers. Leakage, piping, and even embankment breaches pose significant risks to people and property. Locating leakage paths is crucial for preventing piping and leakage, and for dam reinforcement and hazard removal. Currently, geophysical methods used to detect piping and leakage include seismic refraction, resistivity, transient electromagnetic (TEM), ground-penetrating radar (GPR), natural electric field, and pseudo-flow field methods. The pseudo-flow field method, proposed by He Jishan, is a fast and efficient method for detecting leakage inlets. Based on the similarity between flow and electric current fields, this method uses an artificial source current field to approximate the leakage flow field. By measuring the distribution of the current field, the flow direction and relative velocity are determined. Traditional pseudo-flow field methods primarily detect electric field components and are applied underwater, requiring the probe to be kept as close to the bottom as possible. In complex underwater environments and deep water depths, the probe can easily become stuck or entangled with foreign objects, making detection more difficult. While this method accurately locates the leakage inlet, it struggles to reveal the changing trends and direction of the leakage path.

[0003] Therefore, it is necessary to provide a method for quickly locating leakage channels in dams based on total magnetic field gradient measurement. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for quickly locating leakage channels of dams based on total magnetic field gradient measurement, so as to solve the problem that the pseudo-flow field method in the prior art can only locate the leakage entrance but is difficult to reflect the changing trend and direction of the leakage channel.

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

[0006] A method for quickly locating leakage channels in dams based on total magnetic field gradient measurement comprises the following steps:

[0007] Step S101: Power supply electrodes are respectively arranged at the outlet of the leakage channel on the back side of the dam and at a position a certain distance away from the front side of the dam, and current signals of different frequencies are applied to establish a current loop, thereby forming a current channel in the leakage channel;

[0008] Step S102: designing a gradient observation device based on a magnetic sensor, wherein the observation height difference of the magnetic sensor is Δh, and using the gradient observation device to observe the magnetic field component generated by the current channel;

[0009] Step S103: Arranging an observation profile in a direction perpendicular to the leakage channel, and performing three-component magnetic anomaly observation using the gradient observation device;

[0010] Step S104: Calculating the total magnetic field anomaly values ​​at different observation heights using the three-component magnetic anomaly values ​​observed in step S103, and calibrating the lateral position of the leakage channel based on the total magnetic field anomaly intensity;

[0011] Step S105: calculating the longitudinal depth of the leakage channel based on the total magnetic field anomaly values ​​at different observation heights corresponding to the lateral position of the leakage channel in step S104, and calibrating the longitudinal position of the leakage channel;

[0012] Step S106: Combining the transverse calibrated position of the leakage channel in step S104 and the longitudinal calibrated position of the leakage channel in step S105, the water inlet position of the leakage channel is determined to achieve accurate positioning of the leakage channel.

[0013] Furthermore, a method for quickly locating leakage channels of dams based on total magnetic field gradient measurement also includes: using simultaneous transmission technology and receiving technology to improve data anti-interference ability and the positioning accuracy of leakage channels.

[0014] Furthermore, the lateral position calibration step of the leakage channel is specifically as follows:

[0015] According to the total magnetic field anomaly extreme value H corresponding to different frequencies max Corresponding spatial coordinates, marking the lateral position of the current channel;

[0016] The longitudinal position calibration steps of the leakage channel are specifically as follows:

[0017] According to the total magnetic field intensity value H corresponding to the lateral position low and H high The longitudinal buried depth of the leakage channel is calculated using the following formula:

[0018]

[0019] Where: Δh is the vertical height difference between the two magnetic sensors, h is the buried depth of the leakage channel, H high is the total magnetic field strength measured at the higher position, H low is the total magnetic field strength measured at the lower position.

[0020] Furthermore, a method for quickly locating a leakage channel of a dam based on total magnetic field gradient measurement also includes: determining the leakage entrance by combining the lateral position and longitudinal position of the leakage channel with the leakage outlet.

[0021] The present invention has the following beneficial effects:

[0022] This method uses the characteristic that the total magnetic field intensity generated by a leakage channel under artificial source excitation is inversely proportional to the distance to the channel to calculate the buried depth of the leakage channel and locate the leakage channel. The located leakage channel is then combined with the leakage outlet on the back surface of the water to find the water inlet of the leakage channel, overcoming the limitation of traditional pseudo-flow field methods that can only locate the leakage inlet and outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a method for rapidly locating dam leakage channels based on total magnetic field gradient measurement in an embodiment of the present application;

[0024] Figure 2 Schematic diagram of the structure of a method for rapidly locating dam leakage channels based on total magnetic field gradient measurement in an embodiment of the present application;

[0025] Figure 3 Schematic diagram of the spatial position relationship between the gradient observation device and the leakage channel in the embodiment of the present application;

[0026] Figure 4 This is a schematic diagram of the design model in the embodiment of this application;

[0027] Figure 5 The simulation results of the design model by the finite element analysis software in the embodiment of the present application - the total magnetic field intensity curve corresponding to different measurement lines;

[0028] Figure 6 This is a schematic diagram of the simulation results of the design model by the finite element analysis software in the embodiment of the present application - the calibration results of the pipeline lateral position corresponding to different measurement lines;

[0029] Figure 7 This is a comparison chart of the channel burial depth calculated using this example and the actual burial depth at different burial depths in the embodiments of this application. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the specific implementation methods of the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0031] The present invention is based on the basic theory of the charging method. When a leakage channel exists in a dam, the flow of water causes a difference in electrical conductivity between the leakage channel and the surrounding rock. By arranging power supply electrodes on the backwater side and the frontwater side of the dam body, and giving current signals of different frequencies (less than 1kHz), the current will propagate along the dominant channel (leakage channel) with higher electrical conductivity inside the dam, forming a current loop. According to the Biot-Savart theorem, the dominant current channel will generate a magnetic field in space. By arranging two three-component high-precision magnetic sensors with a height difference of Δh on the top of the dam, the total magnetic field anomaly generated by the dominant current channel is observed to obtain the lateral calibration position of the possible leakage path of the dam body. The longitudinal calibration position of the channel can be obtained by combining the lateral calibration position of the leakage path and Δh. Combined with the spatial positioning of the leakage channel and the position of the leakage outlet, the position of the leakage inlet can be determined, thereby realizing the rapid positioning of the leakage channel of the dam.

[0032] like Figure 1-7 As shown, this embodiment provides a method for quickly locating leakage channels in a dam based on total magnetic field gradient measurement, comprising the following steps:

[0033] Step S101: Establish a uniform current field. Power supply electrodes are placed at the outlet of the leakage channel on the back side of the dam and at a certain distance away from the front side of the dam. Current signals of different frequencies are given to establish a current loop, forming a dominant current channel in the leakage channel, such as Figure 2 shown.

[0034] According to the Biot-Savart law, the magnetic induction intensity at the observation point P is

[0035]

[0036] Step S102: Construct a gradient observation device. Design a gradient observation device based on a high-precision magnetic sensor. The magnetic sensor observes a height difference of Δh. Use the gradient observation device to observe the magnetic field component generated by the dominant current channel. The magnetic sensor at a high position is H. high Indicates that the magnetic field measured by the magnetic sensor at the bottom is represented by H low Indicates that Figure 3 shown.

[0037] Step S103: Arrange observation profiles in the direction parallel to the embankment, i.e., perpendicular to the channel, and use the gradient observation device in step S102 to perform three-component magnetic anomaly observation, where the direction parallel to the embankment is the X direction, the direction perpendicular to the embankment is the Y direction, and the vertical downward direction is the Z direction. Figure 4 shown.

[0038] Step S104: Calculate the total magnetic field anomaly values ​​at different observation heights using the three-component magnetic anomaly values ​​observed in step S103. Calibrate the lateral position of the leakage channel based on the total magnetic field anomaly intensity. When the observation point is directly above the leakage pipe, the total magnetic field intensity is the strongest, i.e., H max The corresponding position is the lateral calibration position of the possible leakage channel, such as Figure 5 shown.

[0039] Step S105: Calculate the longitudinal depth of the leakage channel based on the total magnetic field anomaly values ​​at different observation heights corresponding to the lateral position of the leakage channel in step S104, and realize the longitudinal position calibration of the leakage channel, such as Figure 6 shown.

[0040] When the observation point is located directly above the leakage channel, the total magnetic field intensity observed is expressed as follows:

[0041]

[0042] Where I0 is the current intensity flowing through the leakage channel, h is the burial depth of the leakage channel, and the magnetic field intensity at different observation heights is as follows:

[0043]

[0044] Solving the above equations can give the buried depth h of the leakage channel, which is expressed as follows:

[0045]

[0046] Step S106: Combining the horizontal calibration position of the leakage channel in step S104 with the vertical calibration position of the leakage channel in step S105, the leakage channel is quickly and accurately located. Figure 7 shown.

[0047] The present invention utilizes the characteristic that the total magnetic field intensity generated by the leakage channel under artificial source excitation is inversely proportional to the distance to calculate the buried depth of the leakage channel, locate the leakage channel, and combine the located leakage channel with the leakage outlet on the back water surface to find the water inlet of the leakage channel, thus making up for the deficiency of the traditional pseudo-flow field method that can only locate the leakage inlet and outlet.

[0048] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for quickly locating leakage channels in dams based on total magnetic field gradient measurement, characterized in that: The following steps are involved: Step S101: Power supply electrodes are respectively arranged at the outlet of the leakage channel on the back side of the dam and at a certain distance away from the front side of the dam, and current signals of different frequencies are applied to establish a current loop, thereby forming a current channel in the leakage channel; Step S102: Design a gradient observation device based on a magnetic sensor, where the observed height difference of the magnetic sensor is Δ h , observing the magnetic field component generated by the current channel using the gradient observation device; Step S103: Arranging an observation profile in a direction perpendicular to the leakage channel, and performing three-component magnetic anomaly observation using the gradient observation device; Step S104: Calculating the total magnetic field anomaly values ​​at different observation heights using the three-component magnetic anomaly values ​​observed in step S103, and calibrating the lateral position of the leakage channel based on the total magnetic field anomaly intensity; Step S105: calculating the longitudinal depth of the leakage channel based on the total magnetic field anomaly values ​​at different observation heights corresponding to the lateral position of the leakage channel in step S104, and calibrating the longitudinal position of the leakage channel; The steps for calibrating the lateral position of the leakage channel are specifically as follows: According to the extreme values ​​of the total magnetic field anomaly corresponding to different frequencies H max Corresponding spatial coordinates, marking the lateral position of the current channel; The longitudinal position calibration steps of the leakage channel are specifically as follows: According to the total magnetic field strength value corresponding to the lateral position H low and H high The longitudinal buried depth of the leakage channel is calculated using the following formula: ， Where: is the longitudinal height difference between the two magnetic sensors, h is the buried depth of the leakage channel, is the total magnetic field strength measured at the higher position, is the total magnetic field strength measured at the lower position; Step S106: Combining the transverse calibrated position of the leakage channel in step S104 and the longitudinal calibrated position of the leakage channel in step S105, the water inlet position of the leakage channel is determined to achieve accurate positioning of the leakage channel.

2. The method for rapidly locating leakage channels in dams based on total magnetic field gradient measurement according to claim 1, characterized in that: Also includes: Simultaneous transmission and reception technologies are used to improve data anti-interference capabilities and the positioning accuracy of leakage channels.

3. The method for rapidly locating leakage channels in dams based on total magnetic field gradient measurement according to claim 1, characterized in that: Also includes: The leakage inlet is determined by combining the lateral position and the longitudinal position of the leakage channel with the leakage outlet.

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