Layered electric penetration tomography method and system for detecting leakage of reservoir dam

Abstract

The application discloses a layered electric penetration detection method and system for reservoir dam leakage, and the method comprises the following steps: sending a power supply instruction to a power supply device arranged at the junction of a water-facing slope and a water level line, and sending a collection instruction to a measuring device arranged in the longitudinal direction of different elevations of the water-facing slope; the power supply device supplies power after receiving the power supply instruction, a point power source electric field is formed in the dam, and power supply current data is collected; the measuring device measures the voltage of a stable underground electric field after receiving the collection instruction; the power supply current data and the voltage data are normalized, the abnormal transverse position is indicated, the resistivity cross-section graph is inverted based on the power supply current data and the voltage data, the range and trend of the abnormal area are obtained, the normalized potential data of different elevations and the inverted resistivity cross-section graph are constructed according to the spatial coordinates, and the spatial distribution of the leakage channel in the dam body is constructed, so that the leakage hidden danger in the dam body is accurately identified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reservoir dam safety detection, more particularly to a detection technology for soil and rock dam leakage hazards, and specifically to a layered electric penetration detection method and system for reservoir dam leakage. BACKGROUND

[0002] The leakage problem of reservoir dams is an important safety hazard related to the long-term operation of water conservancy projects. Some scholars have proposed many useful methods and complete technologies for dam detection, hazard detection and treatment, but due to the complex conditions of reservoir dam projects and the relatively long construction period, there are still some deficiencies in the precision detection of existing diagnostic techniques. For example, the document "High-resolution detection of geological radar for reservoir dam structure layers" mentions using geological radar to detect several dam bodies, although the ground penetrating radar instrument has the advantages of being light, fast detection speed, large amount of information collected, high resolution, etc., but the penetration depth of electromagnetic waves in the reservoir dam is limited, and the deep rock-soil body cannot be found out; the document "Application of microseismic technology in dam leakage detection" mentions using microseismic exploration to detect reservoir dam leakage, and shows the effect of frequency-wave number method microseismic linear array profile measurement for dam leakage detection. This technology extracts the frequency dispersion curve and visual S-wave velocity imaging to depict the velocity structure of the stratum and delineate the anomaly, which can realize rapid and accurate non-destructive detection of dam leakage, but the microseismic exploration precision is relatively low, and the two dam shoulder rock mass structure also affects the results, and there may be weak and non-convergent microseismic signals in actual application; resistivity method is a feasible method for identifying leakage channels, and the current high-density electrical method measurement line is mainly arranged on the surface of the dam to measure the two-dimensional geoelectric section information at a certain depth below the measurement line. Due to the electrode principle target body, the resolution and reliability of the resistivity are significantly reduced, and the range of the abnormal area is also expanded relative to the true geological body. On the other hand, a single measurement line reveals the vertical characteristics of the hidden hazards, but the leakage channel is distributed in a layered or similar layered manner in space. If the current observation system is used, multiple measurement lines need to be arranged, which to some extent causes low work efficiency. For three-dimensional electrical exploration, the observation system needs to be arranged according to certain rules, which can improve the detection accuracy, but a large number of electrodes need to be arranged on site, and the topography of the dam surface changes a lot. The complex terrain may have some impact on the results.

[0003] In summary, the current measurement line is far away from the target body and mainly detects the resistivity distribution in the depth direction, which has shortcomings in accurately outlining the trend, depth and spatial distribution of the leakage channel. Therefore, it is particularly important to invent an observation system that can approach the leakage hazard and a method that can layer detect the leakage channel for accurately identifying the internal leakage hazard of the dam. SUMMARY

[0004] Therefore, the layered electric penetration detection method and system for reservoir dam leakage are provided to accurately identify the leakage hidden danger in the dam.

[0005] To achieve the above object, the present application adopts the following technical scheme:

[0006] The layered electric penetration detection method for reservoir dam leakage comprises the following steps:

[0007] The power supply device arranged at the intersection of the water-facing slope and the water level line is sent a power supply instruction, and the measuring device arranged in the longitudinal direction of different elevations of the water-facing slope is sent a collection instruction;

[0008] After receiving the power supply instruction, the power supply device supplies power, forms a point power source electric field in the dam, and collects power supply current data; after receiving the collection instruction, the measuring device measures the voltage of the underground stable electric field;

[0009] The power supply current data and the voltage data are normalized, and the inversion resistivity cross-section map is obtained based on the power supply current data and the voltage data; and the normalized potential data of different elevations and the inversion resistivity cross-section map are constructed into the spatial distribution of the leakage channel in the dam body according to the spatial coordinates.

[0010] Preferably, the power supply device comprises a power supply cable, a power supply electrode, and a transmitter; the transmitter transmits power supply current and collects power supply current data to the power supply electrode through the power supply cable; the power supply electrodes adopt independent power supply loops with each other; the power supply electrodes are coupled and contacted with the ground through the water in the reservoir, and form a point power source electric field in the dam by injecting power supply current into the reservoir water;

[0011] The power supply electrode and the power supply cable jointly constitute a power supply electrode string, and the power supply electrode string is arranged at the intersection of the water-facing slope and the water level line.

[0012] Preferably, the measuring device comprises a measuring cable, a measuring electrode, and a receiver; the measuring electrodes adopt independent measuring loops with each other; the measuring electrodes are in contact with the clay of the dam slope, so as to measure the potential at different positions; and the receiver receives the potential difference at the position of the measuring electrode through the measuring cable.

[0013] The measuring electrode and the measuring cable jointly constitute a measuring electrode string; and the measuring electrode string is arranged at the water-facing slope.

[0014] Preferably, the collected power supply current data and voltage data are as follows:

[0015]

[0016] In the formula, I n is the power supply current of the electric field formed by the n number power supply electrodem,n is the potential measured by the mth measuring electrode when the nth power supply electrode is powered, n represents the number of power supply electrodes, and m represents the number of measuring electrodes.

[0017] Preferably, the normalization process specifically includes:

[0018] Extracting the power supply current and the measured voltage of all power supply electrodes and measuring electrodes with the same x-axis coordinate;

[0019] Calculating the normalized potential data by taking the ratio of the measured voltage and the power supply current at the same x-axis measuring point;

[0020] According to the multiple of the distance between the power supply electrodes, the x-axis coordinate of each normalized potential recording point is calculated, and the z-axis coordinate of the normalized potential recording point is calculated according to the distance between the power supply electrodes and the dam crest central axis and the dam crest;

[0021] Obtaining the curve of the normalized potential with the x-axis, and determining the abnormal potential point on the dam axis;

[0022] Repeating the above steps to obtain the normalized potential curves corresponding to multiple measuring devices on the water-back slope, and representing the multiple normalized potential curves according to different recording point depths based on the z-axis coordinates of the normalized potential recording points, to obtain the normalized potential at different depths below the dam crest central axis.

[0023] Preferably, the distribution of resistivity is calculated based on the least square method algorithm with smooth constraint:

[0024] (J T J+λF)Δq k =J T g-λFq k

[0025] In the formula, F is a two-dimensional smoothing filter matrix; q k is a vector formed by taking the logarithm of the resistivity value of the model, J is a Jacobian partial derivative matrix; J T is the transpose matrix of J; λ is a damping factor; q is a resistivity model modification vector; k is the iteration number; g is a residual vector of the measured resistivity and the simulated resistivity.

[0026] A layered electrical penetration detection system for reservoir dam leakage, comprising: a power supply device, a measuring device, a collection unit and a processing unit;

[0027] The power supply device is arranged at the intersection of the water-facing slope and the water level line, and is used to supply power after receiving a power supply instruction, to form a point power source electric field in the dam and collect power supply current data;

[0028] The measuring device is arranged on the water-back slope in different elevation longitudinal directions, and is used to measure the voltage of the underground stable electric field after receiving a collection instruction;

[0029] The collecting unit is used for issuing power supply instruction to the power supply device and the measuring device, realizing synchronous power supply and measurement, and receiving power supply current data and voltage data;

[0030] The processing unit is used for normalizing the power supply current data and the voltage data, and inverting the resistivity cross section based on the power supply current data and the voltage data, and constructing the spatial distribution of the internal leakage channel of the dam body according to the spatial coordinates of the normalized potential data of different elevations and the inverted resistivity cross section.

[0031] Preferably, the power supply device comprises a power supply cable, power supply electrodes and a transmitter; the transmitter transmits power supply current to the power supply electrodes through the power supply cable, and collects power supply current data; the power supply electrodes adopt independent power supply loops; the power supply electrodes are coupled with the earth through water in the reservoir, and form a point power source electric field in the dam through the power supply current injected into the reservoir water.

[0032] The power supply electrodes and the power supply cable jointly form a power supply electrode string; the power supply electrode string is arranged at the junction of the water-facing slope and the water level line.

[0033] Preferably, the measuring device comprises a measuring cable, measuring electrodes and a receiver; the measuring electrodes adopt independent measuring loops; the measuring electrodes are in contact with the clay of the dam slope, so as to measure the potential at different positions; and the receiver receives the potential difference at the position of the measuring electrodes through the measuring cable.

[0034] The measuring electrodes and the measuring cable jointly form a measuring electrode string; the measuring electrode string is arranged at the water-backing slope.

[0035] Advantages of the present application:

[0036] (1) The present application can not only avoid the shortcoming that the detection accuracy of the conventional high-density electrical method decreases with the increase of depth, but also more accurately depict the change of the leakage hidden danger in the cross section, and the detection line is closer to the leakage hidden danger body, thereby obviously improving the detection accuracy.

[0037] (2) The present application greatly reduces the field work amount, realizes the penetration detection of the water-facing slope and the water-backing slope, and realizes the joint detection of different elevation observation systems, and can also show the spatial characteristics of the internal hidden danger of the dam body.

[0038] (3) The normalized potential map has the advantage of quickly identifying the lateral position of the hidden danger, effectively avoids the complex forward and inverse calculation, and obviously improves the work efficiency.

[0039] (4) The layer resistivity inversion section can show the change of the abnormal body on the layer surface, and the penetration detection can more accurately depict the location, range and degree of the leakage hidden danger. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0041] Figure 1 The drawing is a flow chart of a layered electrical penetration detection method for reservoir dam leakage;

[0042] Figure 2 The drawing is a schematic diagram of a layered electrical penetration detection system for reservoir dam leakage;

[0043] Figure 3 The drawing is a processing flow chart of normalized potential;

[0044] Figure 4 The drawing is a spatial perspective view of the power supply device and the measuring device;

[0045] Figure 5 The drawing is a cross-sectional view of the power supply device and the measuring device;

[0046] Figure 6 The drawing is a plan view of the power supply device and the measuring device with equal intervals;

[0047] Figure 7 The drawing is a plan view of the power supply device and the measuring device with unequal intervals;

[0048] Figure 8 The drawing is a schematic diagram for calculating the depth of the normalized potential recording point;

[0049] Figure 9 The drawing is a three-dimensional model diagram of the power supply device and the measuring device;

[0050] Figure 10 The drawing is a plurality of normalized potential diagrams;

[0051] Figure 11 The drawing is an inversion resistivity cross-sectional view.

[0052] 1 - dam crest; 2 - water-facing slope; 3 - water-backing slope; 4 - water level line; 5 - leakage point; 6 - power supply electrode; 7 - power supply cable; 8 - measuring electrode; 9 - measuring cable; 10 - current field; 11 - transmitter; 12 - receiver; 13 - acquisition unit; 14 - processing unit; 15 - saturation line. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0054] The embodiments of the present application disclose a layered electric penetration detection method for reservoir dam leakage, as shown in the formula (I) : Figure 1 The formula (I) comprises the following steps:

[0055] The power supply device arranged at the junction of the water-facing slope and the water level line is sent a power supply instruction, and the measuring device arranged in the longitudinal direction of different elevations of the backwater slope is sent a collection instruction;

[0056] After the power supply device receives the power supply instruction, power supply is performed, a point power source electric field is formed in the dam, and power supply current data is collected; after the measuring device receives the collection instruction, the voltage of the underground stable electric field is measured;

[0057] The power supply current data and the voltage data are normalized, the abnormal transverse position is indicated, the resistivity cross-section graph is inverted based on the power supply current data and the voltage data, the range and trend of the abnormal area are obtained, and the normalized potential data of different elevations and the inverted resistivity cross-section graph are constructed according to the spatial coordinates to obtain the spatial distribution of the leakage channel in the dam body.

[0058] In the present embodiment, as shown in the formula (II) : Figure 2 The power supply device comprises a power supply cable 7, a power supply electrode 6 and a transmitter 11; the transmitter 11 transmits power supply current and collects power supply current data to the power supply electrode 6 through the power supply cable 7; the power supply voltage of the transmitter 11 is less than 36v; the single power supply time length of the transmitter 11 is 2s; the power supply electrodes 6 adopt independent power supply loops; the power supply electrodes 6 are coupled and contacted with the ground through the water in the reservoir, and form a point power source electric field in the dam through the power supply current injected into the reservoir water; the power supply electrode 6 and the power supply cable 7 jointly constitute a power supply electrode string, and the power supply electrode string is arranged at the junction of the water-facing slope and the water level line. The power supply cable 7 is subjected to sealing and waterproof treatment, so as to prevent the water in the reservoir from entering the power supply loop.

[0059] The measuring device comprises a measuring cable 9, a measuring electrode 8 and a receiver 12; the measuring electrodes 8 adopt independent measuring loops; the measuring electrodes 8 are in contact with the clay of the dam slope, so as to measure the potential at different positions; the receiver 12 receives the potential difference at the position of the measuring electrode through the measuring cable; the single measurement interval of the receiver is 0.5s; the measuring electrode 8 and the measuring cable 9 jointly constitute a measuring electrode string; and the measuring electrode string is arranged at the backwater slope 3.

[0060] The application sets the power supply device at the junction of the water-facing slope and the water level line, which is conducive to the full coupling of the power supply electrode and water, ensures that the current can be directly transmitted to the inside of the dam through water, improves the working efficiency, and fully utilizes this condition; the power supply electrode adopts a point power supply mode, the acquisition unit issues a power supply command to the transmitter, the transmitter transmits a rectangular pulse signal to one of the electrodes according to the power supply time, the current passes through the electrode and the water to form a balanced current field in the dam, and in the loop of the transmitter, the power supply electrode, the ground and the infinite electrode, the transmitter can collect the power supply current data, at the same time, the measuring electrode at the backwater slope collects the voltage signal; after the power supply time ends, the transmitter transmits pulses to other electrodes again, and the transmitter still obtains the power supply current data in the power supply loop, and the measuring electrode at the backwater slope also collects the voltage signal, and the power supply and acquisition are sequentially performed, and when all the power supply electrodes complete the power supply, the test of the observation system ends. If there are multiple measuring devices on the backwater slope, the above steps are repeated, wherein the measuring devices are independent between the measuring devices, and the measuring devices and the power supply devices form an observation system.

[0061] In particular, the number of power supply electrodes 6 of the same group of power supply devices is equal to that of the measuring electrodes 8 in the measuring device;

[0062] In particular, the measuring device is arranged on the backwater slope in no less than two lines, and the spacing of the multiple measuring devices can be equal or not equal, and is arranged in the longitudinal direction of different elevations of the backwater slope, as shown in Figure 6 and Figure 7 .

[0063] In particular, the transmitter 11 sequentially supplies power to the power supply electrodes one by one according to the agreed power supply time, so that the power supply electrodes form a stable current field in the reservoir;

[0064] In particular, the clock of the receiver 12 is synchronized with the transmitter 11, and when the transmitter 11 supplies power to the underground through the power supply electrode 6, the receiver 12 obtains the potential difference of the dam measured by the measuring electrode in real time.

[0065] In this embodiment, the power supply and measurement form of the transmitter 11 and the receiver 12 is one transmission and multiple measurements, and the order of power supply and measurement is as follows: the power supply electrode is n, and all the power supply electrodes are sequentially sorted as 1, 2, 3…(n-2), (n-1), n according to the power supply electrode string order; when the measuring electrode is m, all the measuring electrodes are synchronously measured, and the current obtained is I1, the voltage obtained is U 1，1 , U 2，1 , U 3，1 ……U (m-2)，1 , U(m-1)，1 U m，1 When there are two power supply electrodes, all measuring electrodes simultaneously measure data, resulting in a current of I2 and voltages of U. 1，2 U 2，2 U 3，2 ...U (m-2)，2 U (m-1)，2 U m，2 When there is 3 power supply electrodes, all measuring electrodes simultaneously measure data, resulting in a current of I3 and voltages of U. 1，3 U 2，3 U 3，3 ...U (m-2)，3 U (m-1)，3 U m，3 Power supply and measurement are performed sequentially. When all power supply electrodes have been powered on (i.e., when there are n power supply electrodes), all measurement electrodes simultaneously measure data, and the obtained current is I. n The voltages are U 1,n U 2,n U 3,n ...U (m-2),n U (m-1),n U mn The acquisition unit collects current data from the transmitter; after all measuring electrodes have completed their measurements, the acquisition unit collects voltage data from the receiver; and then the acquisition unit uploads the coded current and voltage data to the processing unit.

[0066] The encoded current and voltage data formats are as follows:

[0067]

[0068] In the formula: I n U refers to the supply current U of the electric field formed by the power supply electrode n. m,n This refers to the potential measured by the measuring electrode m when the n-th power supply electrode is powered.

[0069] Normalize the supply current and voltage data to obtain a normalized potential diagram, and indicate the specific steps for identifying the lateral location of the anomaly, such as... Figure 3 As shown:

[0070] Extract the supply current and measurement voltage of all power supply electrodes and each measurement electrode that have the same x-axis coordinate;

[0071] The normalized potential data is obtained by comparing the measured voltage and the supply current at the same x-axis measuring point.

[0072] According to the multiple of the power supply electrode spacing, the x-axis coordinate of each normalized potential recording point is calculated, and the z-axis coordinate of the normalized potential recording point is calculated according to the distance between the power supply electrode and the dam crest middle axis and the distance of the dam crest;

[0073] The curve of the normalized potential changing with the x-axis is obtained, and the abnormal potential point on the dam axis is judged;

[0074] The above steps are repeated to obtain the normalized potential curves corresponding to multiple measuring devices on the backwater slope, and the normalized potential curves are expressed according to different recording point depths based on the z-axis coordinates of the normalized potential recording points, so as to obtain the normalized potential at different depths below the dam crest middle axis.

[0075] Specifically, a coordinate system is established: the starting point of the dam crest middle axis on the left bank is the coordinate origin, the direction along the dam axis is the x-axis direction, the right bank is the positive direction of the x-axis, the direction perpendicular to the dam axis is the y-axis direction, and the upstream is the positive direction of the y-axis; the vertical direction upward from the dam crest is the positive direction of the z-axis, wherein; the 1-time electrode spacing of the power supply electrode is a, the distance between the power supply electrode and the dam crest middle axis is b, and the elevation of the power supply electrode from the dam crest is c; the 1-time electrode spacing of the measuring electrode is a', the distance between the measuring electrode and the dam crest middle axis is b', and the elevation of the measuring electrode from the dam crest is c';

[0076] For the convenience of the definition of the x-axis length and depth later, the xyz coordinates are expressed according to their respective lengths relative to the origin, so that the coordinates of the 1-time power supply electrode with a supply electrode spacing are ((n-1)a, b, -c), and the coordinates of the 1-time measuring electrode with a measuring electrode spacing are ((m-1)a', -b', -c');

[0077] Integrate the data of all power supply electrodes and measuring electrodes with the same x-axis coordinates, that is, when (n-1)a=(m-1)a', the current and voltage data with the same coordinates are (I1, U 1，1 ), (I2, U 2，2 ), (I3, U 3，3 )……(I n-2 , U (m-2，n-2) ), (I n-1 , U (m-1,n-1) ), (I n , U m,n );

[0078] Thus, the normalized potential η is obtained:

[0079]

[0080] In the formula, η n is the normalized potential value corresponding to the nth power supply electrode, and U (m，n)is the potential collected by the mth electrode when the nth electrode is powered. n is the power supply current of the nth electrode.

[0081] Thus, the normalized potential data set varying in the x-axis direction is obtained.

[0082] When the power supply electrode spacing a is equal to the measurement electrode spacing a', that is, the power supply electrode spacing is 1 times the electrode spacing, the coordinates of the normalized potential recording points are:

[0083] (0, 0, -(c'-b'(c'-c) / (b+b'))), (1a, 0, -(c'-b'(c'-c) / (b+b'))), (2a, 0, -(c'-b'(c'-c) / (b+b')))...((n-2)a, 0, -(c'-b'(c'-c) / (b+b'))), ((n-2)a, 0, -(c'-b'(c'-c) / (b+b'))

[0084] When the power supply electrode spacing a is equal to the measurement electrode spacing a', that is, the power supply electrode spacing is k times the electrode spacing, the coordinates of the normalized potential recording points are:

[0085] (0, 0, -(c'-b'(c'-c) / (b+b'))), (k*1a, 0, -(c'-b'(c'-c) / (b+b'))), (k*2a, 0, -(c'-b'(c'-c) / (b+b')))...(k*(n-2)a, 0, -(c'-b'(c'-c) / (b+b'))), (k*(n-2)a, 0, -(c'-b'(c'-c) / (b+b'))

[0086] The position coordinates in the x-axis direction and the data set of the normalized potential are:

[0087] (0, η1), (1a, η2), (2a, η2)...((n-2)a, η (n-1) ), ((n-1)ax, η n ).

[0088] If the power supply electrode spacing is increased to k times the power supply electrode spacing of 1 times, the position coordinates in the x-axis direction and the data set of the normalized potential are:

[0089] (0, η1), (k*1a, η2), (k*2a, η2)...(k*(n-2)a, η (n-1) ), (k*(n-1)ax, η n ).

[0090] When there are multiple measuring devices on the upstream slope, repeat the above steps to finally obtain the normalized potential at different depths below the central axis of the dam crest.

[0091] The normalized potential map is normalized by the power supply current and the measured voltage obtained by the power supply electrode and the measuring electrode with the same abscissa. Since the calculation amount is small, the change in the height of the normalized potential at different abscissas can be seen, which quickly indicates the horizontal position and direction of the hidden danger. When the normalized potential map is a straight line along the x-axis direction, it indicates that the normalized potential changes little on the central axis of the dam, further indicating that the dam is uniform or in a normal seepage state everywhere. When the normalized potential appears a region with a significant decrease along the x-axis direction, there is an abnormal seepage at the site. When the normalized potential appears a region with a significant increase along the x-axis direction, there may be a cavity or rock mass at the site. If there are multiple measuring devices on the upstream slope, the changes of the resistivity at different depths in the dam body can be described, which further helps to track the seepage channel.

[0092] In the present embodiment, the specific steps of the inversion resistivity cross-section map are as follows:

[0093] When the power supply electrode supplies power to the underground, the voltage difference measured by any two measuring electrodes in all measuring electrodes is calculated, thereby forming the current and voltage difference data body under the power supply electric field of the power supply electrode. The current and voltage difference data body under the power supply of all power supply electrodes is sequentially compiled, thereby forming the (I, U) data format.

[0094] For layered resistivity inversion, the least square method algorithm based on smooth constraint is used to invert the resistivity:

[0095] (J T J+λF)Δq k =J T g-λFq k

[0096] In the formula, F is a two-dimensional smoothing filter matrix; q k is a vector formed by taking the logarithm of the resistivity value of the model. J is the Jacobian partial derivative matrix; J T is the transpose matrix of J; λ is the damping factor; q is the resistivity model modification vector; k is the iteration number; g is the residual vector of the measured resistivity and the simulated resistivity.

[0097] A group of resistivity slice maps are obtained by inversion calculation. When there are multiple measuring devices on the upstream slope, a plurality of oblique resistivity cross-section maps are obtained.

[0098] The cross-sectional view, obtained through resistivity inversion calculation, shows the resistivity on the plane formed by the measuring electrode string and the power supply electrode string. It clearly shows the path, range, and location of potential leakage from the upstream slope to the downstream slope. Since dam leakage occurs below the phreatic line, the basis for judging leakage is the low resistivity characteristic of the apparent resistivity. If the inverted resistivity cross-sectional view shows a low-resistivity anomaly from the upstream slope to the downstream slope, it indicates the presence of a leakage channel in that area. If the low-resistivity area on the inverted resistivity cross-sectional view does not show obvious connectivity from the upstream slope to the downstream slope, it indicates a potential seepage anomaly in that area. If the resistivity distribution on the inverted resistivity cross-sectional view is relatively uniform and the variation is small, then there is no potential leakage in that area.

[0099] In this embodiment, a layered electrical penetration detection system for reservoir dam leakage is disclosed, such as... Figure 2 As shown, it includes: a power supply device, a measuring device, a data acquisition unit 13, and a processing unit 14;

[0100] The power supply device is located at the junction of the water-facing slope 2 and the water level line. It is used to supply power after receiving the power supply command, form a point power electric field inside the dam and collect power supply current data.

[0101] The measuring device is set up in the longitudinal direction at different elevations of the back slope 3 to measure the voltage of the underground stable electric field after receiving the acquisition command;

[0102] The acquisition unit 13 is used to send supply and acquisition commands to the power supply device and the measuring device to realize synchronous power supply and measurement, as well as to receive power supply current data and voltage data;

[0103] The processing unit 14 is used to normalize the power supply current data and voltage data, obtain the lateral location of the anomaly, and retrieve the resistivity cross section based on the power supply current data and voltage data to obtain the range and direction of the anomaly area. It also constructs the spatial distribution of the seepage channels inside the dam body by combining the normalized potential data and the retrieved resistivity cross section at different elevations according to spatial coordinates.

[0104] In this embodiment, the power supply device includes a power supply cable 7, power supply electrodes 6, and a transmitter 11. The transmitter 11 transmits power supply current to the power supply electrodes 6 and collects power supply current data via the power supply cable 7. The power supply voltage of the transmitter 11 is less than 36V, and the duration of a single power supply by the transmitter 11 is 2 seconds. The power supply electrodes 6 are connected to each other via independent power supply circuits. The power supply electrodes 6 are coupled to the ground through the water in the reservoir, and a point power electric field is formed inside the dam by injecting power supply current into the reservoir water. The power supply electrodes 6 and the power supply cable 7 together form a power supply electrode string, which is arranged at the junction of the upstream slope and the water level line. The power supply cable 7 is sealed and waterproof to prevent water from the reservoir from entering the power supply circuit.

[0105] The measuring device includes a measuring cable 9, measuring electrodes 8, and a receiver 12. The measuring electrodes 8 are connected by independent measuring circuits. The measuring electrodes 8 are in contact with the clay on the dam slope to measure the potential at different locations. The receiver 12 receives the potential difference at the location of the measuring electrodes via the measuring cable. The interval between each measurement is 0.5s. The measuring electrodes 8 and the measuring cable 9 together form a measuring electrode string. The measuring electrode string is arranged at the back slope 3.

[0106] The working process of this invention is as follows: Figure 4 and Figure 5 As shown, based on the width of the dam crest 1, the upstream slope 2, the downstream slope 3, the dam seepage line 15, and the location of the seepage point 5, power supply electrodes 6 and power supply cables 7 are arranged at the intersection of the upstream slope 2 and the reservoir water level line 4. Multiple rows of measuring devices are arranged on the downstream slope, each row including measuring electrodes 8 and measuring cables 9. The power supply electrode strings and measuring electrode strings are connected to the transmitter 11 and receiver 12 respectively, and the transmitter 11 and receiver 12 are connected to the acquisition unit 13. The acquisition unit 13 is configured with power supply current, measurement time, and power supply voltage, and sends a power supply command to the transmitter 11 and a reception command to the receiver 12. A stable current field 10 is established on the dam by the power supply electrodes, and all measuring electrodes 8 synchronously acquire potential data. After all power supply electrodes 6 have been powered once, sampling stops, and the data is sent to the processing unit 14 via the acquisition unit 13. Data is processed and decompiled on the processing unit to obtain normalized potential maps and layered resistivity inversion slice maps. The lateral location of the leakage point can be quickly identified based on the normalized potential map, and the range and direction of the low-resistivity zone can be described based on the inversion resistivity cross-section map. Normalized potential data and inversion resistivity cross-section maps at different elevations can characterize the spatial location of the leakage channel.

[0107] The present invention will be further illustrated below through specific embodiments:

[0108] like Figure 9 As shown, nine measuring lines (numbered sequentially from the upstream slope a, b, c, d, e, f, g, h, i) are arranged on the dam surface. The power supply and each measuring device have a total of 64 electrodes. Three measuring lines (c, d, e) are set at the dam crest, with a line spacing of 2.5m. Two measuring lines (a and b) are set on the upstream side of the dam, with relative elevations of 3m and 5m from the crest, respectively. Four measuring lines (f, g, h, i) are set on the downstream side of the dam, with relative elevations of 3m, 5m, 8m, and 10m from the crest, respectively, with a point spacing of 1m. The excitation source is a 1A steady-state current, and the reservoir water level is 3m. The upstream and downstream slope ratios of the dam are both 1:2. Figure 8 The figure shown is a schematic diagram of the calculation of the normalized potential recording point depth.

[0109] If survey line a is used as the power supply device, and survey lines g, h, and i are used as the measuring devices, then layered electrical penetration observation systems a and g (first group), a and h (second group), and a and i (third group) can be formed. Figure 10 The normalized potential curves of the first, second, and third observation systems within the range of 0–30 m on the x-axis were extracted. From the curves, the normalized potential of the first group is higher, while the potentials of the second and third groups are relatively close. The difference between the two groups can also be seen from the depth. From the horizontal direction, the normalized potentials of the three groups all show that the normalized potential of the 0–10 m section of the measuring line is relatively low, indicating that there may be a low-resistivity leakage hazard in this area.

[0110] Figure 11 This is a cross-sectional view of the inverse resistivity of the power supply and measuring devices composed of measuring lines a and g. The distribution of resistivity at different locations can be seen from the figure, which also shows the location and direction of the leakage channel.

[0111] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0112] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A layered electro-penetration method for detecting seepage in a reservoir dam, comprising: The application relates to a method for detecting a leakage channel in a dam body. The method comprises the following steps: sending a power supply instruction to a power supply device arranged at the junction of a water-facing slope and a water level line, and sending a collection instruction to a measuring device arranged in a longitudinal direction at different elevations of a backwater slope; The power supply device receives the power supply instruction and supplies power, thereby forming a point power source electric field in the dam body and collecting power supply current data, and the measuring device receives the collection instruction and measures the voltage of a stable electric field underground; The power supply current data and the voltage data are normalized, and a resistivity cross-section graph is inverted based on the power supply current data and the voltage data, so that the normalized potential data at different elevations and the inverted resistivity cross-section graph are constructed according to spatial coordinates to show the spatial distribution of the leakage channel in the dam body; The power supply current data and the voltage data are normalized to obtain a normalized potential graph; The normalized potential graph is obtained by normalizing the power supply current and the measuring voltage of the power supply electrode and the measuring electrode with the same horizontal coordinate, and the normalized potential graph can quickly indicate the horizontal position and direction of the hidden danger due to the small amount of calculation. The power supply device comprises a power supply cable, a power supply electrode and a transmitter; the transmitter transmits power supply current and collects power supply current data to the power supply electrode through the power supply cable; the power supply electrodes are independent of each other; the power supply electrodes are coupled with the earth through water in the reservoir; and the power supply electrodes form a point power source electric field in the dam body through the power supply current injected into the reservoir water. The power supply electrode and the power supply cable jointly form a power supply electrode string, and the power supply electrode string is arranged at the junction of the water-facing slope and the water level line. The normalization process is as follows: The power supply current and the measuring voltage of all power supply electrodes and measuring electrodes with the same x-axis coordinate are extracted; The measuring voltage and the power supply current of the same x-axis measuring point are processed by ratio to obtain normalized potential data; The x-axis coordinate of each normalized potential recording point is calculated according to the multiple of the distance between the power supply electrodes, and the z-axis coordinate of the normalized potential recording point is calculated according to the distance between the power supply electrode and the dam top central axis and the distance between the power supply electrode and the dam top; The curve of the normalized potential changing with the x-axis is obtained, and the abnormal potential point on the dam axis is judged; The above steps are repeated to obtain the normalized potential curves corresponding to the multiple measuring devices on the backwater slope, and the multiple normalized potential curves are represented according to different recording point depths based on the z-axis coordinate of the normalized potential recording point, so that the normalized potential at different depths below the dam top central axis is obtained.

2. The layered electrical penetration detection method for detecting seepage of a reservoir dam according to claim 1, wherein, The measuring device comprises a measuring cable, a measuring electrode and a receiver; the measuring electrodes are independent of each other; the measuring electrodes are in contact with the dam slope clay, thereby measuring the potential at different positions; and the receiver receives the potential difference at the position of the measuring electrode through the measuring cable. The measuring electrode and the measuring cable jointly form a measuring electrode string, and the measuring electrode string is arranged at the backwater slope.

3. The layered electrical penetration probe method for detecting leakage of a reservoir dam according to claim 2, wherein The collected power supply current data and voltage data are as follows: ； In the formulae: I n is the power supply current of the electric field formed by the n number of power supply electrodes, U m,n is the potential measured by the m number of measuring electrodes when the n number of power supply electrodes are powered, n represents the number of power supply electrodes, and m represents the number of measuring electrodes.

4. The layered electrical penetration probe method for detecting seepage of a reservoir dam according to claim 1, wherein, The resistivity is inverted based on the least square method algorithm with a smooth constraint: ； where F is a two-dimensional smoothing filter matrix; q k is a vector formed by taking the logarithm of the resistivity values of the model, J is a Jacobian matrix of partial derivatives; J T is a vector of J is the transpose of The application relates to a method for detecting a leakage channel in a dam body. is a damping factor; q is a resistivity model modification vector; k is the number of iterations; g is a residual vector of the measured resistivity and the simulated resistivity.

5. A layered electro-penetration detection system for reservoir dam leakage, implementing the method of claim 1, characterized by, The method comprises the following steps: sending a power supply instruction to a power supply device arranged at the junction of a water-facing slope and a water level line, and sending a collection instruction to a measuring device arranged in a longitudinal direction at different elevations of a backwater slope; The power supply device receives the power supply instruction and supplies power, thereby forming a point power source electric field in the dam body and collecting power supply current data, and the measuring device receives the collection instruction and measures the voltage of a stable electric field underground; The power supply current data and the voltage data are normalized, and a resistivity cross-section graph is inverted based on the power supply current data and the voltage data, so that the normalized potential data at different elevations and the inverted resistivity cross-section graph are constructed according to spatial coordinates to show the spatial distribution of the leakage channel in the dam body; The power supply current data and the voltage data are normalized to obtain a normalized potential graph; The normalized potential graph is obtained by normalizing the power supply current and the measuring voltage of the power supply electrode and the measuring electrode with the same horizontal coordinate, and the normalized potential graph can quickly indicate the horizontal position and direction of the hidden danger due to the small amount of calculation. The power supply device comprises a power supply cable, a power supply electrode and a transmitter; the transmitter transmits power supply current and collects power supply current data to the power supply electrode through the power supply cable; the power supply electrodes are independent of each other; the power supply electrodes are coupled with the earth through water in the reservoir; and the power supply electrodes form a point power source electric field in the dam body through the power supply current injected into the reservoir water. The power supply electrode and the power supply cable jointly form a power supply electrode string, and the power supply electrode string is arranged at the junction of the water-facing slope and the water level line. The normalization process is as follows: The power supply current and the measuring voltage of all power supply electrodes and measuring electrodes with the same x-axis coordinate are extracted; The measuring voltage and the power supply current of the same x-axis measuring point are processed by ratio to obtain normalized potential data; The x-axis coordinate of each normalized potential recording point is calculated according to the multiple of the distance between the power supply electrodes, and the z-axis coordinate of the normalized potential recording point is calculated according to the distance between the power supply electrode and the dam top central axis and the distance between the power supply electrode and the dam top; The curve of the normalized potential changing with the x-axis is obtained, and the abnormal potential point on the dam axis is judged; The above steps are repeated to obtain the normalized potential curves corresponding to the multiple measuring devices on the backwater slope, and the multiple normalized potential curves are represented according to different recording point depths based on the z-axis coordinate of the normalized potential recording point, so that the normalized potential at different depths below the dam top central axis is obtained. The measuring device comprises a measuring cable, a measuring electrode and a receiver; the measuring electrodes are independent of each other; the measuring electrodes are in contact with the dam slope clay, thereby measuring the potential at different positions; and the receiver receives the potential difference at the position of the measuring electrode through the measuring cable. The measuring electrode and the measuring cable jointly form a measuring electrode string, and the measuring electrode string is arranged at the backwater slope. The collected power supply current data and voltage data are as follows: The resistivity is inverted based on the least square method algorithm with a smooth constraint: The power supply device is arranged at the junction of the water-facing slope and the water level line, and is used to supply power after receiving a power supply instruction, to form a point power source electric field inside the dam and collect power supply current data; The measuring device is arranged in the longitudinal direction of different elevations of the water-leaving slope, and is used to measure the voltage of the underground stable electric field after receiving a collection instruction; The collection unit is used to send a supply and collection instruction to the power supply device and the measuring device, to realize synchronous power supply and measurement, and to receive power supply current data and voltage data; The processing unit is used to normalize the power supply current data and the voltage data, and to invert the resistivity cross section based on the power supply current data and the voltage data, to construct the spatial distribution of the internal leakage channel of the dam body according to the spatial coordinates of the normalized potential data of different elevations and the inverted resistivity cross section.

6. A layered electro-penetration detection system for detecting seepage in a dam of a reservoir according to claim 5, wherein, The power supply device comprises a power supply cable, power supply electrodes and a transmitter; the transmitter transmits power supply current to the power supply electrodes through the power supply cable and collects power supply current data; the power supply electrodes adopt independent power supply loops; the power supply electrodes are coupled and contacted with the earth through the water in the reservoir, and form a point power source electric field inside the dam through the power supply current injected into the reservoir water; The power supply electrodes and the power supply cable jointly constitute a power supply electrode string, which is arranged at the junction of the water-facing slope and the water level line.

7. A layered electro-penetration detection system for detecting seepage in a dam of a reservoir according to claim 6, wherein, The measuring device comprises a measuring cable, measuring electrodes and a receiver; the measuring electrodes adopt independent measuring loops; the measuring electrodes are in contact with the clay of the dam slope, so as to measure the potential at different positions; and the receiver receives the potential difference at the position of the measuring electrodes through the measuring cable; The measuring electrodes and the measuring cable jointly constitute a measuring electrode string; The measuring electrode string is arranged at the water-leaving slope.

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