A three-dimensional electrical observation system combined with metal structures in earth-rock dams

Abstract

The present invention discloses a three-dimensional electrical observation system combined with metal structures in earth-rock dams. The system uses the metal structure in the dam body and the three-dimensional electrical observation system composed of ground electrodes to detect hidden dangers in the dam body. A number of electrodes are arranged on the surface of the dam body to form a three-dimensional observation system, wherein the arrangement of the electrodes is not strictly limited and can be in any form, and the number of electrodes is densely arranged at key parts of the dam such as the shoulder contact zone or serious leakage area, and the arranged electrodes are connected in series with the metal pressure measuring tube or siphon tube and other metal structures in the dam body to the observation system, forming a three-dimensional electrical observation system inside and outside the dam body composed of the "long electrode" of the metal structure inside the dam body and the ground electrode. Then, data collection of the full three-dimensional electrical observation system is carried out.

Description

Technical Field

[0001] The present invention relates to the field of geophysical detection in the work of detecting hidden dangers of leakage in dams, and specifically to a three-dimensional electrical observation system combined with a metal structure in an earth-rock dam, which is a three-dimensional electrical observation system for the inside and outside of a structure that uses a metal pressure measuring tube or a siphon tube inside the dam body itself as a long electrode combined with electrodes arranged on the surface of the dam body to form a combination of electrodes inside the dam body and ground electrodes. Background Art

[0002] As an important water conservancy facility, the safe operation of earth-rock dam plays an important role in ensuring agricultural irrigation and protecting the lives and property of the people. The water storage and water diversion of the reservoir can ensure agricultural irrigation and the safety of the lives and property of the people downstream during the flood season. The main problem affecting the safety of the reservoir is the reservoir leakage problem.

[0003] At present, geophysical methods have been widely used as a non-destructive testing method, but due to the limitations of test conditions of different methods, their sensitivity to the target body is different. For the evaluation of dam foundation stability caused by dam leakage, the DC resistivity method has strong applicability. Through comprehensive comparison and judgment of the electrical parameters of the dam body, the abnormal area can be better determined, providing effective technical parameters for drilling construction. Under the influence of water pressure, the leakage position of the dam is generally in the lower part of the dam body, the contact zone of the dam shoulder and even the dam foundation, which is far away from the surface of the dam body. The current DC electrical detection technology in the detection of reservoir earth-rock dams mostly uses multiple two-dimensional survey lines on the dam surface or three-dimensional survey lines on the ground, or drilling + ground survey lines for three-dimensional electrical exploration of the borehole. The electrode arrangement of the three-dimensional electrical observation system is: the electrodes are arranged according to a certain grid, that is, the distance between the front and rear electrodes is the same. The electrode arrangement in the hole is: a string of electrodes is arranged, and there is a certain distance between the electrodes. However, for safety reasons, drilling is generally not allowed in water conservancy facilities such as reservoir dams, making it difficult to arrange holes for installing electrodes. Electrodes are basically arranged on the ground, which means that the electrodes are relatively far away from the leakage location, making it difficult to measure abnormal signals and obtain good detection results. At the same time, since the dam shoulders and other locations are often not straight lines but irregular shapes, it is difficult to arrange regular electrode grids.

[0004] There are some metal structures with certain functions inside the dam, such as pressure gauges and siphons. The pressure gauge is used to detect the water head height inside the dam, and the siphon is used for automatic flood discharge. These metal structures have no other use except to perform their own functions. Summary of the invention

[0005] In order to realize the three-dimensional electrical method of boreholes and ground, and at the same time not to drill holes on the dam body to destroy the dam body structure, there is no relevant report on the full and reasonable use of the metal structure of the dam body itself for detection. For small and medium-sized reservoir dams, the common metal structures are siphons and pressure gauges. These two structures are generally made of metal. The siphon is a metal pipe along the upper surface of the dam body, and is completely buried in the dam body at the top of the dam. The pressure gauge is generally a galvanized pipe, perpendicular to the dam body, from the surface of the dam body to the dam foundation, with a large depth, and generally there are several uniformly distributed in the dam body. If these two structures are used to excite and receive electrical signals, the signal source is closer to the abnormality, which is more conducive to the reception of abnormal signals. The present invention uses metal structures such as siphons or pressure gauges in the dam body as "long electrodes" to transmit and receive electrical signals, and combines the electrodes on the surface of the dam to form a full-space three-dimensional electrical observation system on the surface and in the dam body. The current three-dimensional electrical data inversion grid can be divided with an unstructured grid, and there is no strict restriction on the spacing of the electrodes, and the electrodes can be arranged arbitrarily.

[0006] To achieve the above purpose, the present invention adopts the following technical solution: a three-dimensional electrical observation system combining ground survey lines with metal structures in the dam body:

[0007] A three-dimensional electrical observation system combined with metal structures in earth-rock dams, wherein a plurality of electrodes are arranged on the surface of the earth-rock dam body, and a survey line connects the electrodes and the metal structures in the dam body in series in any order to form a complete three-dimensional electrical survey line; wherein the electrodes are densely arranged at the shoulder position or the key leakage position of the dam body;

[0008] The electrodes are arranged in a grid shape or in any irregular form; the electrode spacing between the electrodes arranged densely at the abutment position or leakage focus of the dam body is smaller than the electrode spacing at other positions of the dam body;

[0009] The metal structure in the dam body is a metal pressure measuring tube or a metal siphon, or a drill rod for drilling construction of the dam body;

[0010] The electrode is connected to a metal pressure measuring tube, or the electrode is connected to a metal siphon, or the electrode is connected to the metal siphon and the metal pressure measuring tube at the same time, so as to collect three-dimensional data.

[0011] Furthermore, the system also includes a parallel electrical method instrument or a high-density electrical method instrument;

[0012] When performing the three-dimensional data acquisition, the measuring line is connected to a parallel electrical instrument or a high-density electrical instrument to measure the electrical data of a single-point power field or a dipole field, and the emission current I emitted by each electrode and the measured voltage difference ΔU between any two electrodes are recorded.

[0013] Furthermore, the three-dimensional data acquisition also includes positioning measurement of the position of each electrode, and the pressure measuring tube and / or the siphon tube and / or the drill pipe for data processing.

[0014] Furthermore, the three-dimensional electrical observation system pre-processes and inverts the collected data to obtain the three-dimensional electrical distribution characteristics of the detection area, and interprets them in combination with geological data.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. The present invention utilizes the metal structure existing in the dam body to carry out three-dimensional electrical exploration, and no drilling is required on the dam body, thus saving on-site construction time and economic costs.

[0017] 2. Since drilling damages the dam body itself, it will affect the safety of the dam body to a certain extent. The present invention belongs to the real non-destructive testing;

[0018] 3. The present invention uses the metal structure existing in the dam body as a long electrode. The long electrode goes deep into the dam body and is closer to the abnormal position, which is more conducive to the electrode receiving the abnormal signal;

[0019] 4. The ground electrode arrangement of the present invention can be in any form, and there is no requirement for the spacing between electrodes, which is more convenient for on-site construction and is conducive to encrypting measurements of key locations, making the electrode arrangement more reasonable and flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the three-dimensional arrangement of the three-dimensional electrical observation system combining the piezometer and the siphon in the dam body according to the present invention;

[0021] Figure 2 It is an observation system combination of electrode + siphon;

[0022] Figure 3 It is an observation system combination of electrode + pressure tube;

[0023] Figure 4 A grid division diagram of three-dimensional inversion in a specific embodiment;

[0024] Figure 5 is a resistivity distribution map obtained by three-dimensional inversion in a specific embodiment;

[0025] Figure 6 and Figure 7 These are the horizontal and vertical profiles of the three-dimensional resistivity inversion results.

[0026] In the figure: 1-piezometer; 2-electrode; 3-dam shoulder; 4-siphon; 5-electrical instrument. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] Embodiment 1

[0029] This embodiment is a three-dimensional electrical observation system composed of ground electrodes + siphons + pressure measuring tubes.

[0030] In conjunction with the instruction manual Figure 1 , electrodes 2 are randomly arranged on the dam body to be tested, wherein the electrodes are densely arranged at the dam shoulder 3, and the electrode spacing at the dam shoulder 3 is relatively small;

[0031] Connect the electrodes in a certain order, and connect the pressure measuring tube 1 and the siphon tube 4 into the measuring line to form a complete measuring line, which is then connected to the electrical instrument 5 to complete the layout of the on-site three-dimensional observation system;

[0032] There is no particular order restriction for connecting the electrodes;

[0033] After the observation system is arranged, the coordinates of each electrode are located and recorded for data processing. The electrode number and coordinate recording format are shown in Table 1.

[0034] Table 1 Electrode number and coordinate recording format

[0035] Electrode No. X Y Z 1 <![CDATA[x 1 ]]> <![CDATA[y 1 ]]> <![CDATA[z 1 ]]> 2 <![CDATA[x 2 ]]> <![CDATA[y 2 ]]> <![CDATA[z 2 ]]> 3 <![CDATA[x 3 ]]> <![CDATA[y 3 ]]> <![CDATA[z 3 ]]> ...... x... y... z...

[0036] The dipole-dipole electrical data of this observation system are collected, and the numbers of the transmitting electrode and the receiving electrode and the corresponding current and potential difference are recorded. The recording form is shown in Table 2;

[0037] Table 2 Dipole-dipole power supply measurement data record table

[0038] A B M N V / I(ohm) I(mA) 3 4 2 1 3.817082 83.36306 4 5 3 2 2.656164 70.75729 5 6 4 3 1.627295 94.12132 5 4 3 1 1.071288 94.12132 6 7 5 4 1219146 100.3073 6 8 4 2 0.9965 100.3073 7 8 6 5 1.12652 88.3104 7 9 5 3 0.794906 88.3104 7 10 4 1 0.857096 88.3104 ...... ...... ...... ...... ...... ......

[0039] Preprocess the measured 3D data volume: merge the coordinates of each electrode and the power supply measurement data into an inversion file and perform 3D inversion. The 3D inversion grid is divided into unstructured grids. The results of the division are shown in Figure 4 ;

[0040] The conjugate gradient algorithm is used to invert the 3D electrical data of the dam body to obtain the 3D electrical distribution characteristics in the dam body. Figure 5 Three-dimensional inversion resistivity distribution map of the dam body. Figure 5 This is the three-dimensional resistivity inversion result diagram. Figure 6 and Figure 7are the horizontal and vertical profiles of the three-dimensional resistivity inversion results, respectively. Figure 6 is a slice diagram along the axial center of the dam crest, Figure 7 The position is a slice diagram along the axial center perpendicular to the dam top. Figure 6 and Figure 7 From the slices along the top of the dam body and perpendicular to the top, it can be determined that the leakage hazards of the dam body are located 100m from the axis of the dam top and 80m in the horizontal direction.

[0041] Embodiment 2

[0042] This embodiment is a three-dimensional electrical observation system composed of ground electrodes + siphons.

[0043] In conjunction with the instruction manual Figure 2 , electrodes 2 are randomly arranged on the dam body to be tested, wherein the electrodes are densely arranged at the dam shoulder 3, and the electrode spacing at the dam shoulder 3 is relatively small;

[0044] Connect the electrodes in a certain order, and connect the siphon 4 to the measuring line to form a complete measuring line, which is then connected to the electrical instrument 5 to complete the arrangement of the on-site three-dimensional observation system.

[0045] There is no particular order restriction for connecting the electrodes;

[0046] After the observation system is arranged, the coordinates of each electrode are located and recorded for data processing, and then the dipole-dipole electrical data of this observation system are collected, and the numbers of the transmitting and receiving electrodes and the corresponding current and potential difference are recorded. The measured three-dimensional data body is preprocessed: the coordinates and power supply measurement data of each electrode are merged into an inversion file, and a three-dimensional inversion is performed. The three-dimensional electrical distribution characteristics in the dam body are obtained. Then the results are interpreted.

[0047] Embodiment 3

[0048] This embodiment is a three-dimensional electrical observation system composed of ground electrodes + pressure measuring tubes.

[0049] In conjunction with the instruction manual Figure 3 , electrodes 2 are randomly arranged on the dam body to be tested, wherein the electrodes are densely arranged at the dam shoulder 3, and the electrode spacing at the dam shoulder 3 is relatively small;

[0050] Connect the electrodes in a certain order, and connect the pressure measuring tube 1 to the measuring line to form a complete measuring line, which is then connected to the electrical instrument 5 to complete the layout of the on-site three-dimensional observation system.

[0051] There is no particular order restriction for connecting the electrodes;

[0052] After the observation system is arranged, the coordinates of each electrode are located and recorded for data processing. Then the dipole-dipole electrical data of this observation system are collected, the transmitting electrode and receiving electrode numbers and the corresponding current and potential difference are recorded, and the measured three-dimensional data body is preprocessed: the coordinates of each electrode and the power supply measurement data are merged into an inversion file, and a three-dimensional inversion is performed. The three-dimensional electrical distribution characteristics in the dam body are obtained. Then the results are interpreted.

Claims

1. A three-dimensional electrical observation system combined with metal structures in earth-rock dams, characterized by: A plurality of electrodes are arranged on the surface of the earth-rock dam body, and the measuring line connects the electrodes and the metal structure in the dam body in series in any order to form a complete three-dimensional electrical measuring line; wherein the electrodes are densely arranged at the shoulder position or the key leakage position of the dam body; The electrodes are arranged in a grid shape or in any irregular form; the electrode spacing between the electrodes arranged densely at the abutment position or leakage focus of the dam body is smaller than the electrode spacing at other positions of the dam body; The metal structure in the dam body is a metal pressure measuring tube or a metal siphon; The electrode is connected to a metal pressure measuring tube, or the electrode is connected to a metal siphon, or the electrode is connected to any of these two metal structures to perform three-dimensional data acquisition; The system also includes a parallel electrical method instrument or a high-density electrical method instrument; When performing the three-dimensional data acquisition, the measuring line is connected to a parallel electrical instrument or a high-density electrical instrument and electrical data measurement of a single-point power field or a dipole field is performed, and the emission current I emitted by each electrode and the measured voltage difference ΔU between any two electrodes are recorded; The three-dimensional data acquisition also includes positioning measurement of the position of each electrode, and the pressure measuring tube and / or the siphon tube for data processing; The three-dimensional electrical observation system pre-processes and inverts the collected data to obtain the three-dimensional electrical distribution characteristics of the detection area and interprets them in combination with geological data; The metal structure is used as a long electrode to transmit and receive electrical signals, and is combined with electrodes on the surface of the dam to form a full-space three-dimensional electrical observation system on the surface and inside the dam.

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