A geomembrane leakage monitoring method

Abstract

The application discloses a geomembrane leakage monitoring method, which comprises the following steps: coating a first conductive layer and a second conductive layer on the front and back surfaces of a geomembrane respectively; arranging a plurality of first conductive wires on the first conductive layer at intervals and arranging a plurality of second conductive wires on the second conductive layer at intervals; connecting each first conductive wire to a positive electrode of a power supply / negative electrode of the power supply in sequence and connecting each second conductive wire to the negative electrode of the power supply / positive electrode of the power supply in sequence; measuring and recording current values in a circuit to obtain a current value data set; and determining the position of a leakage point of the geomembrane according to the current value data set. The application can accurately locate the position of the leakage point of the geomembrane, thereby reducing the replacement area of the geomembrane and lowering the maintenance cost of the geomembrane.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geomembrane leakage monitoring, and particularly relates to a geomembrane leakage monitoring method. BACKGROUND

[0002] The geomembrane is a waterproof barrier type material taking high molecular polymer as a basic raw material, has excellent corrosion resistance and cracking resistance, and is often used for tailing storage fields, channel seepage prevention, subway engineering, etc.

[0003] With the social development and the wide use of the geomembrane in engineering, people pay attention to the leakage point monitoring of the geomembrane, and the geomembrane monitoring gradually enters the research topics of various scientific research institutions.

[0004] The geomembrane monitoring mainly refers to the monitoring of the geomembrane after laying. When placing the equipment after laying, the dipole method in the electrical monitoring method is often used. The equipment used in the dipole method is flexible and portable, and the detection accuracy is high. The dipole method needs to insert a probe into the geomembrane. When it is found that the geomembrane is damaged, it is usually difficult to determine the accurate position of the leakage point. Therefore, the geomembrane in the region can only be replaced as a whole. However, the geomembrane is extremely expensive, and the replacement of the geomembrane in the region around the probe will greatly increase the maintenance cost. SUMMARY

[0005] The purpose of the application is to provide a geomembrane leakage monitoring method which can accurately monitor the leakage point position of the geomembrane, reduce the replacement area of the geomembrane, and reduce the maintenance cost.

[0006] The application adopts the following technical scheme: a geomembrane leakage monitoring method comprising the following steps:

[0007] A first conductive layer and a second conductive layer are respectively coated on the front and back surfaces of the geomembrane;

[0008] A plurality of first conductive wires are arranged on the first conductive layer at intervals, and a plurality of second conductive wires are arranged on the second conductive layer at intervals; wherein the conductivity of the first conductive wire is greater than the conductivity of the first conductive layer, the conductivity of the second conductive wire is greater than the conductivity of the second conductive layer, adjacent first conductive wires do not intersect, adjacent second conductive wires do not intersect, and the projection of the first conductive wire on the second conductive layer intersects the second conductive wire;

[0009] Each first conductive wire is connected to the positive electrode / negative electrode of the power supply in turn, and each second conductive wire is connected to the negative electrode / positive electrode of the power supply in turn, the current value in the circuit is measured and recorded, and a current value data set is obtained;

[0010] The leakage point position of the geomembrane is determined according to the current value data set.

[0011] Furthermore, determining the location of the geomembrane leakage point based on the current value data set includes:

[0012] The current value data set is processed by interpolation to obtain the processed current value data set.

[0013] Generate a current equipotential diagram based on the processed current value data set;

[0014] The location of the highest peak of the equipotential line in the current equipotential diagram on the geomembrane is taken as the location of the leakage point.

[0015] Further, sequentially connecting each first conductive wire to the positive / negative terminal of the power supply and sequentially connecting each second conductive wire to the negative / positive terminal of the power supply includes:

[0016] When the positive / negative terminal of the power supply is connected to the first conductive wire X (a) a At that time, the negative / positive terminals of the power supply are connected sequentially to the second conductive line Y1 to Y2. b Where a and b are both positive integers.

[0017] Furthermore, several first conductive lines are parallel to each other, and the first spacing between any two adjacent first conductive lines is equal.

[0018] Furthermore, several second conductive lines are parallel to each other, and the second spacing between any two adjacent second conductive lines is equal.

[0019] Furthermore, both the first and second conductive lines are straight lines, and the first spacing is equal to the second spacing.

[0020] The beneficial effects of this invention are as follows: By coating the front and back sides of the geomembrane with a first conductive layer and a second conductive layer respectively, and combining the first and second conductive wires, the geomembrane is effectively divided into several small areas. By measuring the current values ​​in the circuits formed by different first and second conductive wires, and in conjunction with the current equipotential diagram, the leakage point of the geomembrane can be accurately located, thereby reducing the area of ​​geomembrane replacement and lowering the maintenance cost of the geomembrane. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the geomembrane structure after the conductive layer and conductive wires are provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the equivalent circuit after adding a conductive layer and conductive lines in an embodiment of the present invention;

[0023] Figure 3 This is a current flow diagram after applying voltage across the same conductive line in an embodiment of the present invention;

[0024] Figure 4A current trend graph after adding voltage at both ends of the different conductive lines in the embodiment of the present application;

[0025] Figure 5 A current trend graph when the positive and negative poles of the power supply are connected to the first and second conductive lines respectively and the geomembrane has no leakage in the embodiment of the present application;

[0026] Figure 6 A current trend graph when the positive and negative poles of the power supply are connected to the first and second conductive lines respectively and the geomembrane has leakage in the embodiment of the present application;

[0027] Figure 7 A top view structural schematic diagram of the geomembrane in the monitoring experiment in the embodiment of the present application;

[0028] Figure 8 A side view structural schematic diagram of one surface of the geomembrane in the monitoring experiment in the embodiment of the present application;

[0029] Figure 9 A circuit schematic diagram in the monitoring experiment in the embodiment of the present application;

[0030] Figure 10 A circuit schematic diagram after adding leakage points in the monitoring experiment in the embodiment of the present application;

[0031] Figure 11 A current equipotential diagram corresponding to Table 1 in the embodiment of the present application;

[0032] Figure 12 A circuit schematic diagram when two leakage points in the monitoring experiment in the embodiment of the present application;

[0033] Figure 13 A current equipotential diagram corresponding to Table 2 in the embodiment of the present application;

[0034] Figure 14 A current flow direction schematic diagram on the geomembrane when there is no leakage point in the embodiment of the present application;

[0035] Figure 15 A current trend graph when the leakage point of the geomembrane contacts the upper high-resistance conductive layer in the embodiment of the present application;

[0036] Figure 16 A current trend graph when the leakage point of the geomembrane does not contact both the upper and lower high-resistance conductive layers in the embodiment of the present application;

[0037] Figure 17 A current trend graph when the leakage point of the geomembrane contacts the lower high-resistance conductive layer in the embodiment of the present application. DETAILED DESCRIPTION

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0039] This invention discloses a method for monitoring geomembrane leakage, comprising the following steps: coating a first conductive layer and a second conductive layer on the front and back sides of the geomembrane respectively; arranging a plurality of first conductive lines at intervals on the first conductive layer and a plurality of second conductive lines at intervals on the second conductive layer; wherein the conductivity of the first conductive lines is greater than the conductivity of the first conductive layer, the conductivity of the second conductive lines is greater than the conductivity of the second conductive layer, adjacent first conductive lines do not intersect, adjacent second conductive lines do not intersect, and the projection of the first conductive lines on the second conductive layer intersects with the second conductive lines; sequentially connecting each first conductive line to the positive / negative terminal of a power supply and sequentially connecting each second conductive line to the negative / positive terminal of a power supply, measuring and recording the current value in the circuit to obtain a current value dataset; and determining the location of the geomembrane leakage point based on the current value dataset.

[0040] This invention coats the front and back of the geomembrane with a first conductive layer and a second conductive layer, respectively, and combines them with first and second conductive wires. This is equivalent to dividing the geomembrane into several small areas. By measuring the current values ​​in the circuits formed by different first and second conductive wires and using the current equipotential diagram, the leakage point of the geomembrane can be accurately located, thereby reducing the area of ​​geomembrane replacement and lowering the maintenance cost of the geomembrane.

[0041] Specifically, coating the geomembrane with a first conductive layer and a second conductive layer on both sides means coating the geomembrane with the first conductive layer on the front side and the second conductive layer on the back side. Alternatively, the first conductive layer can be coated on the back side of the geomembrane, and the second conductive layer on the front side.

[0042] In practice, the first conductive layer and the second conductive layer can be made of the same or different materials. For ease of description, they are simply referred to here as the first conductive layer and the second conductive layer, also known as the high-resistivity conductive layer. Similarly, the first conductive wire and the second conductive wire can also be made of the same or different materials, provided that the resistivity of the first conductive wire is much greater than the resistivity of the first conductive layer, and the resistivity of the second conductive wire is much greater than the resistivity of the second conductive layer. Preferably, the resistivity of the second conductive wire is also much greater than the resistivity of the first conductive layer, and vice versa. This ensures that the applied current flows in the circuit according to a predetermined rule.

[0043] like Figure 1 The diagram shows a geomembrane structure with conductive layers and conductive lines. The upper high-resistivity conductive layer (i.e., the first conductive layer) has a low-resistivity longitudinal conductive line (i.e., the first conductive line) embedded in it. The middle layer is a conventional non-conductive geomembrane layer. The lower high-resistivity conductive layer (i.e., the second conductive layer) has a low-resistivity transverse conductive line (i.e., the second conductive line) embedded in it.

[0044] In the upper layer high resistance conductive layer, delta is the thickness of the upper layer high resistance conductive layer, the thickness is thin and can be ignored, L1 represents the length of the upper layer measured high resistance conductive layer in the current direction, and D represents the length perpendicular to the upper layer high resistance conductive layer. According to the formula of the resistance law, the resistance of the high resistance conductive layer is:

[0045]

[0046] In the formula, p represents the resistivity of the high resistance conductive layer, L1 represents the resistance length in the current direction, and S represents the cross-sectional area of the high resistance conductive layer perpendicular to the current direction (assuming that the high-conductive material is coated very thick, it is approximately in the form of a cuboid, and the cross-sectional area of the high resistance conductive layer perpendicular to the current direction is S). According to formula (1), when L1=D, that is, the plan view of the geomembrane is a square, the surface resistance is only related to the material thickness delta, and is independent of the other values, that is:

[0047]

[0048] In one embodiment, determining the leakage point position of the geomembrane according to the current value data set comprises: processing the current value data set by an interpolation method to obtain a processed current value data set; generating a current equipotential map according to the processed current value data set; and taking the position corresponding to the highest peak (referring to the maximum current) of the equipotential line on the geomembrane as the leakage point position.

[0049] By generating a current equipotential map according to the processed current value data set, the position of the highest peak of the equipotential line can be observed, so as to determine the specific position of each leakage, and the positioning accuracy can be improved.

[0050] In the embodiment of the application, sequentially connecting each first conductive wire to the positive / negative electrode of the power supply and sequentially connecting each second conductive wire to the negative / positive electrode of the power supply comprises: when the positive / negative electrode of the power supply is connected to the a-th first conductive wire X a , the negative / positive electrode of the power supply is sequentially connected to the second conductive wire Y1 to Y b ; wherein a and b are positive integers.

[0051] By this connection method, the geomembrane is equivalent to being divided into a plurality of small areas, and the measured current value is based on the current value at the vertex of each small area, which facilitates providing accurate current value and positioning for the current equipotential map, and can greatly reduce the range of the leakage point.

[0052] In one embodiment, the first conductive lines are parallel to each other, and the first spacing between any two adjacent first conductive lines is equal. The second conductive lines are parallel to each other, and the second spacing between any two adjacent second conductive lines is equal. The first conductive lines and the second conductive lines are straight lines, and the first spacing is equal to the second spacing.

[0053] The present application studies a set of digital grid geomembrane monitoring methods to locate the leakage point position. The method measures current instead of potential and other parameters, so that the detection process is easier to measure, and the detection result is more accurate. By using the interpolation algorithm in Matlab, the range and experimental accuracy of the current equipotential diagram can be adjusted. When used, the required range and accuracy can be adjusted according to actual needs.

[0054] In the actual monitoring process, the upper high-resistance conductive layer and the lower high-resistance conductive layer are separated by a non-conductive geomembrane. The upper layer is separated by a longitudinal low-resistance line (i.e. the first conductive line) as the positive electrode of the power supply, and the lower layer is separated by a transverse low-resistance line (i.e. the second conductive line) as the negative electrode of the power supply. The longitudinal lines are sequentially powered, and the longitudinal line with the lowest voltage is found. Conversely, the lower layer is powered by the transverse line, and the upper layer is grounded. The transverse grid is sequentially powered, and the transverse line with the lowest voltage is found, which can obtain the leakage point coordinates.

[0055] In the embodiment of the present application, first conductive lines and second conductive lines with a conductivity much greater than that of the first conductive layer and the second conductive layer are added to the first conductive layer and the second conductive layer. For example, the resistivity of the conductive line is 100 times that of the conductive layer. The equivalent circuit diagram is as shown in Figure 2 , wherein the white line is the conductive line. When a power supply is added to both ends of the conductive line, the current trend on the geomembrane can be simulated as Figure 4 , which is the right side of the simulation circuit diagram. In the diagram, R 导电层 = 100 x R 高导层 , where R 导电层 is the resistance of the conductive layer, and R 高导层 is the resistance of the conductive line.

[0056] The conductivity of the low-resistance conductive line is much higher than that of the conductive layer, so most of the current on the geomembrane flows into the low-resistance conductive line, and a small part flows into the high-resistance conductive layer.

[0057] Therefore, adding positive and negative electrodes to both ends of a certain low-resistance conductive line will produce a current trend as shown in the current trend diagram of Figure 3 . The current on the low-resistance conductive line gradually decreases in the Figure 3 median value with the consumption of resistance, and because the resistance value of the high-resistance conductive layer is much higher than that of the low-resistance conductive grid, the current value in the dashed line part is almost 0 mA.

[0058] In the Figure 3The block diagram marked in the middle serves as a partial schematic diagram of the geomembrane. When the current flows from the positive pole to the negative pole and passes through the low-resistance conductive wire, its principle can be seen from the simulation circuit diagram on the far right: as shown in equation (3), although the conductivity of the high-resistance conductive material is much lower than that of the low-resistance conductive wire, there will still be current flowing to the conductive layer.

[0059] ρ 导电 <<ρ 高导 (3)

[0060] like Figure 4 As shown, positive and negative terminals of a power source are added to different ends of the low-resistivity conductive wire. Current flows from the positive terminal through the low-resistivity conductive wire and the high-resistivity conductive layer to the negative terminal. Because the conductivity of the high-resistivity conductive layer and the low-resistivity conductive wire differs significantly, current preferentially flows towards the low-resistivity conductive wire when flowing on the geomembrane.

[0061] In one embodiment, assuming the geomembrane has no leaks, the positive terminal of the power supply is applied to X. 10 At point Y1, the negative terminal of the power supply is applied, and the current distribution is as follows: Figure 12 As shown, when there are no leaks in the geomembrane, current will not flow from the upper layer to the lower layer.

[0062] like Figure 5 The diagram shows the front and back of the geomembrane. The conductive wires of the upper layer of the geomembrane are connected to the positive terminal of the power supply, and the conductive wires of the lower layer are connected to the negative terminal. When there are no leaks, because the positive and negative terminals of the power supply are not on the same plane, no conductive loop is formed. Therefore, no current flows. The digital geomembrane shown in the diagram is the geomembrane after the addition of the conductive layer and conductive wires.

[0063] like Figure 6 The current flow diagram simulating the presence of a leak shows that when a leak exists in the geomembrane, the current flows from the positive terminal of the power supply through the leak into the negative terminal.

[0064] Current trend on geomembrane and Figure 4 The current flow diagrams after applying voltage to different terminals are similar in principle. At this time, Figure 4 In the current flow diagram after applying voltage to different terminals, the negative electrode moves to the lower conductive layer: that is, the current flows out from the positive electrode, passes through the drain point, and then flows into the negative electrode. Because the drain point is on a low-resistance conductive line near the negative electrode, most of the current flows from the drain point through the low-resistance conductive line into the negative electrode, while the current in the remaining part of the high-resistance conductive layer is relatively weak. The schematic diagram is similar to... Figure 3 The circuit diagram on the right is similar, therefore it is drawn... Figure 6 When simulating the current trend diagram when there is a leakage point, the main current is emphasized and the weak current is omitted, but the weak current still exists. Figure 6The effect of the leakage point on the upper low-resistance conductive line is different. The upper low-resistance conductive line is sequentially scanned, and when the last two lines are measured, the potential change is the largest near the leakage point. According to the analysis of the potential difference distribution law of the dipole with different power supplies, it can be obtained that the power supply is closest to the leakage point, and the right side suction current is the smallest, and it can be determined that the leakage point is between the two lines.

[0065] From the above analysis, it can be seen that the current on the geomembrane will produce different flow directions according to the different resistivity. When the geomembrane does not have a leakage point, the current cannot pass through the geomembrane from the upper conductive layer to the lower layer; when the geomembrane has a leakage point, the current will flow from the positive electrode to the negative electrode through the leakage point to form a loop, and the maximum current is at the leakage point.

[0066] In addition, when the geomembrane has a leakage point, it can be divided into three cases: the leakage point contacts the upper high-resistance conductive layer (the current flow diagram is as shown in Figure 15 ), the leakage point does not contact the upper and lower high-resistance conductive layers (the current flow diagram is as shown in Figure 16 ), and the leakage point contacts the lower high-resistance conductive layer (the current flow diagram is as shown in Figure 17 ), in which the current will flow into the negative electrode along the direction of the leakage point to form a closed circuit, and the highest value in the entire current flow diagram is the leakage point.

[0067] In a verification test, the geomembrane leakage point monitoring experiment steps are as follows:

[0068] 1. Determine the scheme. At the beginning, the row and column voltage size is determined to be 10V, the distance between the rows (row means the first conductive line, represented by X) and the columns (column means the second conductive line, represented by Y) of the geomembrane is 10cm, the leakage point is simulated by using a conductive wire to connect, and different leakage point measurements are completed at the same time to ensure the same experimental environment.

[0069] The top view structural diagram of the geomembrane after adding the conductive layer and the conductive line is as shown in Figure 7 , and the side view structural diagram of the geomembrane on one surface is as shown in Figure 8 , wherein the conductivity of the conductive line is set to be 100 times the resistivity of the conductive layer.

[0070] 2. Build the circuit, conduct the experiment, and transmit the current data to the upper computer through the high-precision digital display meter.

[0071] As shown in Figure 9 , in the case of no leakage point, 10V voltage is applied to one end of X (X1-X9), and the current output value of Y (Y1-Y9) is detected.

[0072] Because it is an open circuit at this time, the voltmeter will find that the current here is 0mA.

[0073] Then, connect two points (to simulate the leakage point) in the same position (on the front and back) on the geomembrane, as shown in Figure 10 At this time, the current change is found. When the power supply voltage is 10 V, the simulated leakage point position is X = 1.5, Y = 2.5, and the detected current (mA) is shown in Table 1.

[0074] Table 1

[0075]

[0076] The current equipotential map generated by processing the data in Table 1 by the interpolation algorithm is shown in Figure 11 For actual operation, there are necessarily multiple leakage points, so two-point leakage point data analysis and detection are performed. On the basis of the original single leakage point, another wire is connected to make it a double leakage point, as shown in Figure 12 The connection in the figure is the two leakage points, and the above method is measured again. The power supply voltage is 10 V, the simulated leakage point X1 = 1.5, Y1 = 2.5, X2 = 7.5, Y2 = 8.5, and the obtained current (mA) data is shown in Table 2.

[0077] Table 2

[0078]

[0079] The current equipotential map generated by processing the data in Table 2 by the interpolation algorithm is shown in Figure 13 At this time, the current equipotential map can be observed to obtain the current drop trend of the two points, and it is analyzed that there are two leakage points, which will produce the same conclusion as the original hypothesis.

[0080] 3. In the interpolation algorithm of the host computer software, the equipotential line map of the recorded current data is drawn, and the maximum data point is located.

[0081] 4. Whether the maximum data point of the equipotential line is the same as the position of the connected wire on the geomembrane is checked. If they are the same, it is the leakage point (connected wire) of the geomembrane, which verifies the scientificity of the experiment.

[0082] 5. Single-point and two-point leakage point experiments are performed, respectively. If the verification result can satisfy the guess (the leakage point is the connected wire), the above data prove the correctness of the experimental method.

Claims

1. A geomembrane leak monitoring method characterized by, The method comprises the following steps: coating a first conductive layer and a second conductive layer on the front and back surfaces of the geomembrane respectively; arranging a plurality of first conductive wires on the first conductive layer at intervals and a plurality of second conductive wires on the second conductive layer at intervals; wherein the conductivity of the first conductive wires is greater than that of the first conductive layer, the conductivity of the second conductive wires is greater than that of the second conductive layer, adjacent first conductive wires do not intersect, adjacent second conductive wires do not intersect, and the projection of the first conductive wires on the second conductive layer intersects the second conductive wires; connecting each of the first conductive wires to the positive pole / negative pole of the power supply and each of the second conductive wires to the negative pole / positive pole of the power supply in sequence, measuring and recording the current value in the circuit to obtain a current value data set; determining the leakage point position of the geomembrane according to the current value data set; connecting each of the first conductive wires to the positive pole / negative pole of the power supply and each of the second conductive wires to the negative pole / positive pole of the power supply in sequence comprises: When the positive / negative terminal of the power supply is connected to the first a The first conductive line X a At that time, the negative / positive terminals of the power supply are connected sequentially to the second conductive line Y1 to Y2. b ;in, a Both b and b are positive integers.

2. A geomembrane leak monitoring method as claimed in claim 1, wherein, determining the leakage point position of the geomembrane according to the current value data set comprises: processing the current value data set by interpolation to obtain a processed current value data set; generating a current equipotential map according to the processed current value data set; taking the position corresponding to the highest peak of the equipotential line in the current equipotential map on the geomembrane as the leakage point position.

3. A geomembrane leak monitoring method as claimed in claim 2, wherein, The plurality of first conductive wires are parallel to each other, and the first spacing between adjacent two first conductive wires is equal.

4. A geomembrane leak monitoring method as claimed in claim 3, wherein, The plurality of second conductive wires are parallel to each other, and the second spacing between adjacent two second conductive wires is equal.

5. A geomembrane leak monitoring method as claimed in claim 4, wherein, The first conductive wires and the second conductive wires are straight lines, and the first spacing is equal to the second spacing.

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