Transient electromagnetic leakage detection system and method for concrete dam

Abstract

The invention discloses a transient electromagnetic leakage detection system and method for a concrete dam, and relates to the field of transient electromagnetic method detection, the transient electromagnetic leakage detection system comprises a forward modeling system, an auxiliary device system, an acquisition system and an inversion system, and three concrete transient electromagnetic instrument response characteristics of ultralow water content, high water content and crack water saturation and electric signal differences are obtained through forward modeling; a self-made variable-angle anti-interference rapid survey concrete dam transient electromagnetic instrument auxiliary device with automatic distance measurement is adopted to carry out nondestructive testing on the dam; and integrating the collected data and carrying out inversion, drawing a dam apparent resistivity quasi-section diagram of apparent resistivity-detection depth, identifying the moisture distribution condition of the concrete dam, determining abnormal points, and finally realizing nondestructive detection of the internal leakage of the concrete dam. The detection system and method are convenient to operate, and can integrally move, automatically measure the distance and change important parameters such as the detection angle and the distance, so that the transient electromagnetic instrument can detect the leakage of the concrete dam in a lossless, flexible and anti-interference manner.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive detection of concrete dam leakage, and in particular provides a transient electromagnetic leakage detection system and method. Background Art

[0002] my country has a large population and little water resources, and the water resources are unevenly distributed in time and space. Based on this, my country has built countless water conservancy projects to alleviate this problem. With the rapid development of materials science, concrete dams came into being and played an important role in my country's water conservancy system. However, due to technical limitations during the construction period, over time, affected by water pressure, temperature changes, chemical erosion, etc., concrete dams gradually developed cracks, leakage and other problems, endangering the safe operation of the dam.

[0003] At present, the common methods for concrete dam leakage detection are: capacitive sensor method, which is greatly affected by the temperature and type of the dam, and the data is complex and cumbersome to operate; thermal infrared imaging method and microwave scanning method, both of which have the disadvantage of poor penetration and can only measure the surface of the dam.

[0004] Transient electromagnetic method is an artificial source time domain electromagnetic method that has matured in recent years. Its detection process is simple and efficient, with a wide detection range. It is often used in scenes such as geological water flushing structures around tunnels, karst fissures, and leakage surveys of earth-rock dams. Because the good conductors such as steel bars in concrete dams affect the detection accuracy of transient electromagnetic instruments, transient electromagnetic method has not yet been promoted in the field of concrete dam leakage detection. Therefore, it is urgent to further improve the existing transient electromagnetic detection devices and methods. Summary of the invention

[0005] The present invention solves the problem of detecting concrete dam leakage with existing transient electromagnetic instruments, and the detection system and method of the present invention are easy to operate, can be moved as a whole, automatically measure distance, and change important parameters such as detection angle and spacing, so as to realize non-destructive, flexible and interference-proof detection of concrete dam leakage with transient electromagnetic instruments.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical scheme:

[0007] A transient electromagnetic leakage detection system for concrete dams, comprising a forward modeling system, an auxiliary device system, a collection system, and an inversion system;

[0008] The forward modeling system obtains the transient electromagnetic instrument response characteristics and electrical signal differences of three types of concrete with ultra-low water content, high water content, and crack saturation by forward modeling, and stores them as a database for inversion comparison of transient electromagnetic instrument data for dams;

[0009] The auxiliary device system includes a support part and a platform part, wherein the platform part is a support platform and an instrument host platform of an integrated structure, and the support part is mounted on the support platform;

[0010] The acquisition system is composed of a transmitting and receiving coil placed on the support part and a transient electromagnetic instrument host placed on the instrument host platform, and the transmitting and receiving coil and the transient electromagnetic instrument host are connected through a data transmission line;

[0011] The inversion system converts the collected electrical signals into resistivity data, draws a pseudo-section diagram of apparent resistivity and detection depth, identifies the moisture distribution of the concrete dam, converts the apparent resistivity data into moisture content data, and determines abnormal points.

[0012] Further technology of the present invention:

[0013] Preferably, the support portion includes a telescopic rod for adjusting the angle of the transmission and reception coil and measuring the distance, and a frame for supporting the transmission and reception coil.

[0014] Preferably, the auxiliary device system further comprises a distance measuring part arranged on the platform part, and the distance measuring part consists of a distance measuring wheel and a display.

[0015] Preferably, the data is collected in sequence at equal intervals, and the main process is to supply a stable current into the sending loop to generate a stable primary magnetic field, and generate a decaying secondary magnetic field after power failure. The "good conductor" affects the secondary magnetic field and generates different electrical signals.

[0016] Preferably, the process of determining the abnormal point includes: first identifying the possible range of the abnormal point, generating a fine measurement plan within this range, shortening the spacing, adjusting the telescopic rod to measure at multiple angles, and repeating the above steps until the precise position of the abnormal point is obtained.

[0017] The present invention also provides a method for transient electromagnetic leakage detection of concrete dams, the method comprising the following steps:

[0018] S1 forward modeling: forward modeling obtains the transient electromagnetic instrument response characteristics of concrete with ultra-low water content, high water content, and crack saturation;

[0019] S2 parameter selection: determine the survey line direction, number of survey lines, pulse width and spacing according to the scope of the concrete dam to be measured;

[0020] S3 Data Collection: Adjust the telescopic rod of the auxiliary device according to the selected height and angle parameters, and collect data at equal intervals in sequence;

[0021] S4 Inversion: Integrate data and perform inversion, draw a pseudo-section of apparent resistivity and detection depth, identify the moisture distribution of the concrete dam, determine the possible range of the abnormal point, and repeat the above steps through a detailed measurement plan to obtain the precise location of the abnormal point.

[0022] The beneficial effects of the present invention are:

[0023] The auxiliary device disclosed in the present invention can automatically measure distance in conjunction with a transient electromagnetic instrument and move as a whole. Only one person is required to operate and complete the detection task, thereby greatly improving the detection efficiency.

[0024] The auxiliary device disclosed in the present invention can adjust the measuring angle of the transient electromagnetic instrument's transmitting and receiving coil and the distance from the concrete dam surface, and can reduce the error caused by inaccurate placement of the transmitting and receiving coil compared with manual operation, thereby achieving high stability, multi-angle and multi-distance detection.

[0025] The concrete dam transient electromagnetic leakage detection system and method disclosed in the present invention improve detection accuracy and detection efficiency compared with the detection method before modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is the transient electromagnetic instrument auxiliary device in the patent of this invention

[0028] Figure 2 Schematic diagram of three measurement planes of the transient electromagnetic instrument auxiliary device in the present invention

[0029] Figure 3 Schematic diagram of different spacing measurements of the transient electromagnetic instrument auxiliary device in the present invention

[0030] Figure 4 Leakage detection results of concrete dam before improvement

[0031] Figure 5 Improved concrete dam leakage detection results

[0032] Among them: 1. receiving and transmitting coil, 2. telescopic rod, 3. frame, 4. rubber wheel, 5. bracket platform, 6. distance measuring wheel, 7. display instrument, 8. instrument host platform, 9. transient electromagnetic instrument host, 10. handle, 11. data transmission line. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be further described in detail below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention but not all. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] like Figure 1 , the present invention provides a transient electromagnetic leakage detection system for concrete dams, including a forward modeling system, an auxiliary device system, a collection system, and an inversion system;

[0035] The forward modeling system obtains the transient electromagnetic instrument response characteristics and electrical signal differences of three types of concrete with ultra-low water content, high water content, and crack saturation by forward modeling, and stores them as a database for inversion comparison of transient electromagnetic instrument data for dams;

[0036] The auxiliary device system includes a support part and a platform part, wherein the platform part is a support platform 5 and an instrument host platform 8 of an integrated structure, and the support part is mounted on the support platform 5;

[0037] The support part includes a telescopic rod 2 for adjusting the angle and distance of the transmission and reception coil 1 and a frame 3 for supporting the transmission and reception coil 1. By adjusting the length of the telescopic rod 2, the transmission and reception coil 1 can be measured horizontally, vertically or at a certain angle and at different distances.

[0038] The auxiliary device system further comprises a distance measuring part arranged on the platform part, and the distance measuring part is composed of a distance measuring wheel 6 and a display instrument 7, so that the distance measurement and data collection are carried out synchronously.

[0039] The platform part is also provided with a handle 10 and a rubber wheel 4 for pushing the auxiliary device to move as a whole.

[0040] The acquisition system is composed of a receiving and transmitting coil 1 placed on the support part and a transient electromagnetic instrument host 9 placed on the instrument host platform 8. The receiving and transmitting coil 1 and the transient electromagnetic instrument host 9 are connected through a data transmission line 11. The direction of the measuring line, the number of measuring lines, the pulse width and the spacing are determined according to the range of the concrete dam to be measured, and data are collected in sequence at equal spacing;

[0041] The data is collected in sequence at equal intervals. The main process is to supply a stable current into the sending loop to generate a stable primary magnetic field, and generate a decaying secondary magnetic field after power failure. The "good conductor" affects the secondary magnetic field and generates different electrical signals.

[0042] The inversion system converts the collected electrical signals into resistivity data, draws a pseudo-section diagram of apparent resistivity and detection depth, identifies the moisture distribution of the concrete dam, converts the apparent resistivity data into moisture content data, and determines abnormal points.

[0043] The process of determining the abnormal point includes: firstly identifying the possible range of the abnormal point, generating a fine measurement plan within this range, shortening the spacing, adjusting the telescopic rod 2 to measure at multiple angles, and repeating the above steps until the accurate position of the abnormal point is obtained.

[0044] Example: Taking the vertical side of a concrete hyperbolic arch dam crest and measuring a depth of 100m as an example, the specific steps are as follows:

[0045] S1 forward: Figure 1 The auxiliary device shown detects concrete with ultra-low water content, high water content, and crack saturated concrete, and then stores the obtained different transient electromagnetic instrument response characteristics into a data set for future use.

[0046] S2 selects parameters: Determine the survey line direction as vertical according to the measurement range of the concrete dam, select 4 turns of 6m long transmitting and receiving coils and 40 turns of 6m long receiving and receiving coils to form a 1m*1m side length receiving and receiving coil and data transmission line, the number of survey lines is 30, the pulse width is 5ms, the spacing is 2m, and the vertical distance from the dam surface is 1m.

[0047] S3 Data collection: Adjust the telescopic rod of the auxiliary device according to the selected height and angle parameters, and collect data at equal intervals along the dam top.

[0048] S4 Inversion: Integrate data and perform inversion, draw a pseudo-section of apparent resistivity and detection depth, identify the moisture distribution of the concrete dam, determine the possible range of the abnormal point, and repeat the above steps through a detailed measurement plan to obtain the precise location of the abnormal point.

[0049] Comparison of the dam body test results before reconstruction (see Figure 4 ), the result after transformation (see Figure 5 ) eliminates the interference signals generated by good conductors such as steel bars, making the results closer to the actual situation.

[0050] It should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A transient electromagnetic leakage detection system for concrete dams, characterized in that: Including forward modeling system, auxiliary device system, acquisition system, inversion system; The forward modeling system obtains the transient electromagnetic instrument response characteristics and electrical signal differences of three types of concrete with ultra-low water content, high water content, and crack saturation by forward modeling, and stores them as a database for inversion comparison of transient electromagnetic instrument data for dams; The auxiliary device system includes a support part and a platform part, wherein the platform part is a support platform and an instrument host platform of an integrated structure, and the support part is mounted on the support platform; The acquisition system is composed of a transmitting and receiving coil placed on the support part and a transient electromagnetic instrument host placed on the instrument host platform, and the transmitting and receiving coil and the transient electromagnetic instrument host are connected through a data transmission line; The inversion system converts the collected electrical signals into resistivity data, draws a pseudo-section diagram of apparent resistivity and detection depth, identifies the moisture distribution of the concrete dam, converts the apparent resistivity data into moisture content data, and determines abnormal points.

2. According to the concrete dam transient electromagnetic leakage detection system described in claim 1, it is characterized in that: The support part comprises a telescopic rod for adjusting the angle and measuring the distance of the transmission and reception coil and a frame for supporting the transmission and reception coil.

3. A concrete dam transient electromagnetic leakage detection system according to claim 2, characterized in that: The auxiliary device system also includes a distance measuring part arranged on the platform part, and the distance measuring part is composed of a distance measuring wheel and a display instrument.

4. A concrete dam transient electromagnetic leakage detection system according to claim 3, characterized in that: The data is collected in sequence at equal intervals. The main process is to supply a stable current into the sending loop to generate a stable primary magnetic field, and generate a decaying secondary magnetic field after power failure. The "good conductor" affects the secondary magnetic field and generates different electrical signals.

5. A transient electromagnetic leakage detection system for concrete dams according to claim 4, characterized in that: The process of determining the abnormal point includes: firstly identifying the possible range of the abnormal point, generating a fine measurement plan within the range, shortening the spacing, adjusting the telescopic rod to measure at multiple angles, and repeating the above steps until the accurate position of the abnormal point is obtained.

6. The detection method of the transient electromagnetic leakage detection system for concrete dams according to claim 5, characterized in that: The method is implemented in the following steps: S1 forward modeling: forward modeling obtains the transient electromagnetic instrument response characteristics of concrete with ultra-low water content, high water content, and crack saturation; S2 parameter selection: determine the survey line direction, number of survey lines, pulse width and spacing according to the scope of the concrete dam to be measured; S3 Data Collection: Adjust the telescopic rod of the auxiliary device according to the selected height and angle parameters, and collect data at equal intervals in sequence; S4 Inversion: Integrate data and perform inversion, draw a pseudo-section of apparent resistivity and detection depth, identify the moisture distribution of the concrete dam, determine the possible range of the abnormal point, and repeat the above steps through a detailed measurement plan to obtain the precise location of the abnormal point.

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