Method and device for pre-evaluating key parameters of operating conditions of resistance heating technology

Abstract

The present invention discloses a method and device for pre-evaluating key parameters of the operating conditions of resistance heating technology. The method includes: S1: Divide the area to be measured into different test blocks, and measure the soil moisture content and conductivity of each test block; S2: Construct a plurality of electrode wells in each test block according to an equilateral triangle or regular hexagon layout, and determine the depth of each electrode well; S3: Select the corresponding electrode wells, and group and bury a plurality of electrodes at the bottom of the selected electrode wells; S4: Connect each electrode to the output end of an isolation voltage regulator through a corresponding cable. After powering on the electrodes, measure the input current of each electrode with a clamp ammeter, calculate the corresponding average resistance of each group of electrode wells respectively and record it; S5: Calculate the maximum values of the input voltage and input current of each group that meet the requirement of the electrode input power; S6: Determine the models and specifications of the isolation voltage regulator, thyristor and cable required for actual electrothermal remediation.

Description

Technical Field

[0001] The present invention relates to the technical field of resistance heating, and in particular, to a method and device for pre-evaluating key parameters of the operating conditions of resistance heating technology. Background Art

[0002] Resistance heating technology is a mainstream technology that can be used for in-situ remediation of organic contaminated soil and groundwater. It has the advantages of short remediation cycle, high removal rate, wide application range, and controllable secondary pollution, and has been widely commercialized abroad. In recent years, resistance heating technology has gradually received attention and emphasis in China. However, at present, this technology is still in its infancy. Most of the research is indoor small-scale simulation research, and there are few actual engineering application cases, lacking relevant engineering experience.

[0003] Resistance heating is based on Joule's law (Q = I 2 Rt). By burying electrodes underground and allowing current to flow between the electrodes, the soil itself acts as a resistor to generate heat, raising the temperature of the soil and groundwater. By adjusting the magnitude of the input power of the electrodes, the heating rate of the soil can be controlled to meet the heating or heat preservation requirements. According to the power formula P = U*I, the input power of the electrodes depends on the input voltage and current. Therefore, the key parameters of the operating conditions of resistance heating technology are the input voltage and input current. These two parameters determine the specification selection of the equipment and materials required for resistance heating, such as isolation transformers, thyristors, and cables.

[0004] According to Ohm's law I = U / R, the input voltage and current of the electrodes are also related to the soil resistance in the circuit and the electrode layout (equivalent to multiple soil resistors in parallel). Table 1 is a reference value comparison table of the resistivity of different soils. As shown in Table 1, for different types of soils, the soil resistivity varies greatly, even differing by dozens to hundreds of times; the soil resistivity is also affected by the soil moisture content. For the same type of soil, if the moisture content is different, for example, located in the vadose zone and the saturated zone respectively, the resistance difference is also significant; in addition, for the soil at a contaminated site, its resistivity will also be affected by the discharged pollutants. For example, if the groundwater contains salts and alkalis, the pollutants themselves or their decomposition products will increase the conductivity of the soil.

[0005] Table 1 Reference value comparison table of the resistivity of different soils

[0006]

[0007] China has a vast territory, and there are significant differences in soil types and moisture contents between the north and the south. Especially for the soil at polluted sites, due to the diversity of pollution situations and production histories, it is very difficult to accurately grasp the soil resistance of each site. Furthermore, in the engineering scheme design of resistance heating, it is difficult to determine key operating condition parameters such as input voltage and input current, which easily leads to problems such as the selected specifications of equipment and materials not meeting the requirements, resulting in increased resource waste and costs or inability to meet the heating requirements. Therefore, there is an urgent need for a method and device that can pre-evaluate the key parameters of the operating conditions of resistance heating technology, so as to scientifically and reasonably select equipment and materials, while meeting the requirements and reducing the input costs. Summary of the Invention

[0008] To solve the above problems, the present invention provides a method and device for pre-evaluating the key parameters of the operating conditions of resistance heating technology. By dividing the test blocks, selecting electrode wells according to soil types and depth positions for resistance measurement, calculating the parameter values required for soil heating in the project, and more accurately determining the model specifications of each equipment and material, it can not only meet the requirements of on-site implementation but also avoid the situation of increased costs due to resource waste.

[0009] To achieve the above object, the present invention provides a method for pre-evaluating the key parameters of the operating conditions of resistance heating technology, which includes:

[0010] Step S1: Divide the overall area to be measured into different test blocks according to the vadose zone and the saturated zone, and further according to different soil types, and measure the soil moisture content and conductivity of each test block;

[0011] Step S2: Construct multiple electrode wells in each test block according to an equilateral triangle or regular hexagon layout, and determine the depth of each electrode well according to the lower boundary position of the range to be heated and repaired;

[0012] Step S3: Select corresponding electrode wells according to the soil moisture content and conductivity measured in different test blocks, and bury multiple electrodes at the bottom of the selected electrode wells respectively. Specifically:

[0013] Only according to the soil type to be heated and repaired, select at least 3 electrode wells as a group in each type of soil, and bury the same number of electrodes as the selected electrode wells at the bottom of the selected electrode wells respectively; and

[0014] According to the depth of the soil position to be heated and repaired, select at least 3 electrode wells as a group in the vadose zone and the saturated zone of the same soil type respectively, and bury the same number of electrodes as the selected electrode wells at the bottom of the selected electrode wells respectively;

[0015] Step S4: Each electrode is connected to the output terminal of the isolation regulator through the corresponding cable. After powering on the electrode, the input current of each electrode is measured by a clamp ammeter, and the average resistance value R of each group of electrode wells is calculated respectively. 平均值n And record it, where n is a positive integer greater than 0;

[0016] Step S5: According to the results of all the average resistance values, and in combination with the following formulas (1) - (2), calculate the input voltage U required for heating and repairing each area where the demand for the electrode input power P is satisfied. n And the maximum value of the input current I n , where the electrode input power P is a preset value.

[0017] P = I n 2 *R 平均值n (1)

[0018] U n = I n *R n (2)

[0019] Step S6: Determine the models and specifications of the isolation regulator, thyristor, and cable required during the actual electrothermal repair according to the maximum values of the input voltage U n and the input current I n .

[0020] In an embodiment of the present invention, the diameter of each electrode well in step S2 is 10 - 30 cm, and the distance between every two electrode wells is 3 - 10 m.

[0021] In an embodiment of the present invention, a switch is provided on each cable connecting the electrodes, and the output of the isolation regulator is alternating current.

[0022] In an embodiment of the present invention, the preset value of the electrode input power P in step S5 is 1 - 5 kW / m.

[0023] To achieve the above object, the present invention provides a device for pre - evaluating key parameters of the operating conditions of the resistance heating technology, which is used to execute the foregoing method, and includes:

[0024] An isolation regulator, whose input terminal is electrically connected to the external 380V AC power supply line;

[0025] Multiple electrodes, which are used to be inserted into the soil of the formation to be repaired;

[0026] Multiple cables, which are respectively connected between each electrode and an output terminal of the isolation regulator;

[0027] Multiple switches, which are respectively arranged on each cable.

[0028] In one embodiment of the present invention, the output voltage range of the isolation regulator is 0 to 800V; the maximum current load of each cable is 0 to 92A.

[0029] In one embodiment of the present invention, each electrode is a tubular splicable electrode made of metal. An external thread is provided at the top of each electrode, and an internal thread is provided at the bottom of each electrode. The two electrodes can be connected together by screwing the corresponding internal thread and external thread; a cable fixing bolt is provided on the side wall of each electrode for connecting and fixing the cable joint.

[0030] In one embodiment of the present invention, the electrode is further provided with an electrode cap. A lifting ring is provided at the top of the electrode cap for lifting the electrode during construction. An internal thread corresponding to the external thread of the electrode is also provided inside the electrode cap for covering the top of the electrode.

[0031] The method and device for pre-evaluating key parameters of the operating conditions of the resistance heating technology provided by the present invention, compared with the prior art, its main advantages include:

[0032] (1) The operating condition parameters obtained by the pre-evaluation method are measured results, eliminating the interference of various factors such as soil type, moisture content, and circuit layout. The results are highly accurate, effectively overcoming the problem of inaccurate theoretical calculations. The results are more instructive, making the subsequent resistance heating scheme design and equipment material selection more scientific and reasonable;

[0033] (2) The pre-evaluation method is easy to operate, requires low equipment cost, and is easy to promote;

[0034] (3) The electrodes used are splicable electrodes, whose length is adjustable, which can meet the needs of different thickness strata. Their transportation, storage, use, and maintenance are more convenient, and the electrodes can be recycled, facilitating repeated use, energy conservation, and environmental protection. Brief Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is a flowchart of the method according to an embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the electrode structure according to an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the electrode cover structure according to an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the electrode layout according to an embodiment of the present invention;

[0040] Figure 5 Structural diagram of the device according to an embodiment of the present invention.

[0041] Description of reference numerals: 201 - external thread; 202 - internal thread; 203 - cable fixing bolt; 301 - lifting ring; 501 - electrode; 502 - cable; 503 - switch; 504 - isolating voltage regulator. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] Figure 1 For the method flowchart according to an embodiment of the present invention, as Figure 1 shown, this embodiment provides a method for pre - evaluating key parameters of the operating conditions of the resistance heating technology, which includes:

[0044] Step S1: Divide the overall area to be measured into different test blocks according to the vadose zone and the saturated zone, and further according to different soil types, and measure the soil moisture content and electrical conductivity of each test block; generally, according to different water - holding conditions, the rock and soil layers below the ground surface can be divided into the vadose zone and the saturated zone. Among them, below the ground surface, above the stable groundwater table is the vadose zone, and below the stable groundwater table is the saturated zone. In this embodiment, dividing each test block according to the vadose zone, the saturated zone, and different soil types can better test different soils separately;

[0045] Among them, the soil types include clay, sand, miscellaneous / filled soil, etc.

[0046] Step S2: Construct a plurality of electrode wells in each test block according to a spatial layout such as an equilateral triangle or a regular hexagon, and determine the depth of each electrode well according to the lower boundary position of the range to be heated and repaired; among them, the lower boundary position of the range to be heated and repaired can also be regarded as the distribution range of soil pollutants. That is to say, the deeper the pollutant distribution, the deeper the depth setting of the electrode well;

[0047] In this embodiment, the diameter of each electrode well in step S2 is 10 to 30 centimeters (cm) (10 cm ≤ diameter ≤ 30 cm), and the distance between every two electrode wells is 3 to 10 meters (m), that is, 3 m ≤ the distance between the centers of every two electrode wells ≤ 10 m.

[0048] Step S3: Select corresponding electrode wells according to the soil moisture content and conductivity measured in different test blocks, and bury multiple electrodes at the bottoms of the selected electrode wells respectively. Specifically:

[0049] Only according to the type of soil to be heated and repaired, select at least 3 electrode wells as a group in each type of soil, and bury the same number of electrodes as the selected electrode wells at the bottoms of the selected electrode wells respectively; and

[0050] According to the depth of the soil to be heated and repaired, select at least 3 electrode wells as a group in the vadose zone and saturated zone of the same soil type respectively, and bury the same number of electrodes as the selected electrode wells at the bottoms of the selected electrode wells respectively;

[0051] Since the depth of each electrode well is determined according to the lower boundary position of the range to be heated and repaired, in engineering, it is generally the clay layer formation position within the pollution range, where pollutants are likely to accumulate; or a certain depth interval that needs to be heated. For example, the pollution depth of a certain site is 0 to 35 m, and the underground burial depth is 32 m, mainly sand layer; among them, the clay layer is at 9 to 11 m, and the pollutants are concentrated. In addition, the capillary zone is at 31 to 32 m, which is also a pollutant accumulation area. Conventional extraction methods are difficult to completely remove the pollutants in these two formations. Therefore, it is necessary to heat these two specific depths of 9 to 11 m and 31 to 32 m. To ensure the heating effect, these two depths can also be appropriately extended, such as 8.5 to 11.5 m, 30 to 33 m, etc.

[0052] Step S4: Each electrode is connected to the output terminal of the isolation regulator through a corresponding cable. After powering on the electrode, measure the input current of each electrode with a clamp ammeter, and calculate the average resistance R of each group of electrode wells respectively 平均值n and record, where n is a positive integer greater than 0;

[0053] In this embodiment, a switch is provided on each cable connecting the electrodes to facilitate controlling the power on and off of the corresponding electrode, and the output of the isolation regulator is alternating current.

[0054] After power is supplied to the electrodes, since alternating current is provided, the magnitude and direction of the current change with time and there is a phase difference. Therefore, the phases of adjacent electrodes are different, and a current loop can be formed. The input voltage of each electrode in the circuit is adjusted by an isolating regulator, and then the input current of each electrode in the circuit is measured using a clamp ammeter. Then, the average value R of the circuit resistance corresponding to each region is calculated separately. 平均值n For a specific example, please refer to Table 2. For example, in the first group, which is the area with sandy soil, taking 3 electrodes as an example, when the input voltage of the isolating regulator is set to U1, the measured input currents of each electrode are I11, I12, and I13 respectively. According to R = U / I, the resistances of the circuits of the 3 electrodes are calculated as R11, R12, and R13 respectively. Then, the average resistance value of the first group is calculated as R 平均值1 =(R11 + R12 + R13) / 3. Similarly, the average resistance values of each region such as the clay area (such as the second group), the vadose zone of sandy soil (such as the (n - 1)th group), and the saturated zone of sandy soil (such as the nth group) are calculated respectively. The specific calculation process will not be elaborated here.

[0055] Table 2 Test values of key operating parameters for resistance heating in different regions

[0056]

[0057] Step S5: According to the results of all average resistance values and combined with the following formulas (1) - (2), calculate the input voltage U n and the input current I n required for heating and repairing each region that meets the requirement of the electrode input power P, where the electrode input power P is a preset value.

[0058] P = I n 2 *R 平均值n (1)

[0059] U n = I n *R n (2)

[0060] In this embodiment, the preset value of the electrode input power P in step S5 is 1 - 5 kW / m, that is, 1 kW ≤ the input power per unit length (m) of the electrode ≤ 5 kW.

[0061] Step S6: According to the input voltage U n and the input current I nThe maximum value determines the models and specifications of equipment and materials such as isolation regulators, thyristors, and cables required during actual electrothermal remediation. Through the determined model specifications in the selected area, it can not only meet the heating power requirements for soil remediation but also ensure the optimization of equipment and material costs.

[0062] Figure 2 Schematic diagram of the electrode structure according to an embodiment of the present invention, as Figure 2 shown. In this embodiment, the electrode is a tubular (hollow) splicable electrode, and its material is metal. An external thread 201 is provided at the top of each electrode, and an internal thread 202 is provided at the bottom of each electrode. Two electrodes can be connected together by screwing the internal thread 202 and the external thread 201 respectively to meet the requirements of different lengths. For example, multiple electrodes can be threaded together through the internal and external threads to obtain electrodes of different lengths; a cable fixing bolt 203 is provided on the side wall of each electrode for connecting and fixing a cable joint, such as a joint in the form of a wire nose. The cable joint (wire nose) can be fixedly connected to the electrode by tightening the cable fixing bolt 203.

[0063] Among them, the material of the electrode can be a metal material such as carbon steel, and the diameter can be selected as DN50 - DN200 (DN is the English abbreviation of nominal diameter, which is the standardized diameter of containers and pipelines, etc., and the value is larger than the inner diameter but smaller than the outer diameter). The length of a single electrode can be uniformly selected as 1 - 3m. The present invention does not strictly limit its size and material.

[0064] Figure 3 Schematic diagram of the electrode cap structure according to an embodiment of the present invention, as Figure 3 shown. In this embodiment, the electrode is further configured with an electrode cap. A lifting ring 301 is provided at the top of the electrode cap for hoisting the electrode during construction. An internal thread corresponding to the external thread 201 of the electrode is also provided inside the electrode cap for covering the top end of the electrode. The electrode cap can also be made of carbon steel like the electrode. The present invention does not strictly limit it.

[0065] In an embodiment of the present invention, according to the preliminary investigation of a certain site where resistance heating remediation is to be carried out, the pollutants are mainly concentrated in the vadose zone 2 - 5m sand layer and the saturated zone 9 - 11m fine sand layer. Therefore, it is necessary to focus on depth - specific heating of these two strata. Figure 4 Schematic diagram of the electrode layout according to an embodiment of the present invention, as Figure 4As shown, in this embodiment, referring to the subsequent actual engineering design, with an equilateral triangle layout, the well spacing is set to 5 m, and three electrode wells are constructed, each with a depth of 11 m. According to needs, the electrodes are field-spliced into two length specifications of 3 m (for example, splicing three 1-m single rods) and 2 m (for example, splicing two 1-m single rods). Cable joints are fixed on each spliced electrode, and the electrodes are respectively buried into two specified depth positions of 2 - 5 m and 9 - 11 m through hoisting.

[0066] Close the switch to connect the electrodes to the isolating voltage regulator through the cable to form a circuit loop.

[0067] Adjust the input voltage of the isolating voltage regulator, and successively measure the resistance heating operation condition parameters of two different depth formations. Record the input current at different input voltages, and calculate the average value of the corresponding circuit resistance. For specific measured values, please refer to Table 3.

[0068] Table 3 Resistance Heating Operation Parameter Test Table

[0069]

[0070] According to the test results in Table 3, the following can be obtained according to the aforementioned formulas (1) - (3):

[0071] For the unsaturated fine sand layer, the average resistance is about 9 Ω. According to the empirical value (input power per unit length of the electrode is 1 - 2 kW / m), the target input power of the electrode is set to 3 - 6 kW (the electrode length in this area is 3 m). The maximum value of the live wire voltage input for the key operation parameter of resistance heating is about 330 V, and the maximum value of the input current is about 36 A;

[0072] For the saturated fine sand layer, the average resistance is about 3.5 Ω. According to the empirical value (input power per unit length of the electrode is 1 - 2 kW / m), the target input power of the electrode is set to 2 - 4 kW (the electrode length in this area is 2 m). The maximum value of the live wire voltage input for the key operation parameter of resistance heating is about 204 V, and the maximum value of the input current is about 59 A.

[0073] Taking the above results into consideration, to meet the power demand of resistance heating at this site, for recoverable or shared equipment materials such as isolating voltage regulators and thyristors, the model specifications of voltage and current should be appropriately greater than 380 V and 60 A respectively; for non-recoverable or dedicated equipment materials such as cables buried underground, the current specifications for the unsaturated zone and the saturated zone can be respectively selected as models appropriately greater than 36 A and 59 A to reduce costs. The load conditions of different cable models can be referred to in Table 4.

[0074] Table 4 Load of Different Cable Models

[0075] <![CDATA[Line number (mm 2 )]]> Maximum current (A) Maximum load (kW) 1.5 18 3.96 2.5 26 5.72 4 32 7.04 6 47 10.34 10 66 14.52 16 92 20.24 25 120 26.4 35 150 33

[0076] Figure 5 The structural diagram of the device according to an embodiment of the present invention is as follows Figure 5 As shown, this embodiment provides a device for pre-evaluating key parameters of the operating conditions of the resistance heating technology, which is used to implement the method of the foregoing embodiment, and includes:

[0077] An isolation regulator 504, whose input end is electrically connected to the external 380V AC power supply line;

[0078] Multiple electrodes 501, which are used to be inserted into the soil of the formation to be repaired;

[0079] Multiple cables 502 are respectively connected between each electrode 501 and an output end of the isolation regulator 504;

[0080] Multiple switches 503 are respectively arranged on each cable 502.

[0081] In this embodiment, the output voltage range of the isolation regulator 504 is 0-800V, which can meet the voltage requirements for resistance heating repair of most formation types such as clay, silt, sand, and gravel, as well as the voltage requirements under different soil moisture contents in the vadose zone or saturated zone; the maximum current load of each cable 502 can be 0-92A, which can meet the current load requirements in most cases.

[0082] The main advantages of the method and device for pre-evaluating key parameters of the operating conditions of the resistance heating technology provided by the present invention include:

[0083] (1) The operating condition parameters obtained through the pre-evaluation method are measured results, eliminating the interference of various factors such as soil type, moisture content, and circuit layout. The results are highly accurate, effectively overcoming the problem of inaccurate theoretical calculations. The results are more instructive, making the subsequent resistance heating scheme design and equipment material selection more scientific and reasonable;

[0084] (2) The pre-evaluation method is easy to operate, requires low equipment cost, and is easy to promote;

[0085] (3) The electrodes used are spliced electrodes, whose length is adjustable, which can meet the needs of different thickness formations. Their transportation, storage, use, and maintenance are more convenient, and the electrodes can be recycled, facilitating repeated use, energy conservation, and environmental protection.

[0086] Those of ordinary skill in the art can understand that the drawings are only schematic diagrams of an embodiment, and the modules or processes in the drawings are not necessarily essential for implementing the present invention.

[0087] Those of ordinary skill in the art can understand that the modules in the device in the embodiments can be distributed in the device in the embodiments as described in the embodiments, or can be correspondingly changed to be located in one or more devices different from the present embodiments. The modules in the above embodiments can be combined into one module, or can be further split into multiple sub-modules.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for pre-evaluating key parameters of the operating conditions of resistance heating technology, characterized in that, Including: Step S1: Divide the overall area to be measured into different test blocks according to the vadose zone and the saturated zone, and further according to different soil types, and measure the soil moisture content and electrical conductivity of each test block; Step S2: Construct multiple electrode wells in each test block according to an equilateral triangle or regular hexagon layout, and determine the depth of each electrode well according to the lower boundary position of the range to be heated and repaired; Step S3: Select corresponding electrode wells according to the soil moisture content and electrical conductivity measured in different test blocks, and bury multiple electrodes at the bottom of the selected electrode wells respectively. Specifically: Only according to the soil type to be heated and repaired, at least 3 electrode wells are selected as a group in each type of soil, and the same number of electrodes as the selected electrode wells are buried at the bottom of the selected electrode wells respectively; And According to the depth of the soil position to be heated and repaired, at least 3 electrode wells are selected as a group in the vadose zone and the saturated zone of the same soil type respectively, and the same number of electrodes as the selected electrode wells are buried at the bottom of the selected electrode wells respectively; Step S4: Each electrode is connected to the output terminal of the isolation regulator through the corresponding cable. After powering on the electrodes, the input current of each electrode is measured by a clamp ammeter, and the corresponding average resistance value R of each group of electrode wells is calculated respectively 平均值n and recorded, where n is a positive integer greater than 0; Step S5: According to the result of the average value of all resistances, and in combination with the following formulas (1) - (2), calculate the input voltage U required for heating and repairing each group in the area that meets the requirement of the electrode input power P n and the maximum value of the input current I n where the electrode input power P is a preset value P = I n 2 *R 平均值n (1) U n = I n * R n (2) Step S6: Determine the model and specification of the isolation regulator, thyristor, and cable required for actual electric heating repair according to the maximum value of the input voltage U n and the input current I n .

2. The method according to claim 1, wherein The diameter of each electrode well in Step S2 is 10 - 30 cm, and the distance between every two electrode wells is 3 - 10 m.

3. The method according to claim 1, characterized in that, A switch is arranged on each cable connecting the electrodes, and the output of the isolation voltage regulator is alternating current.

4. The method according to claim 1, characterized in that, The preset value of the input power P of the electrode in Step S5 is 1 - 5 kW / m.

5. A device for pre-evaluating key parameters of the operating conditions of a resistance heating technology, which is used to execute the method described in any one of claims 1 to 4, and is characterized in that, Including: An isolation voltage regulator, whose input end is electrically connected to the external 380V AC power supply line; Multiple electrodes, used for inserting into the soil of the formation to be repaired; Multiple cables, respectively connected between each electrode and an output end of the isolation voltage regulator; Multiple switches, respectively arranged on each cable.

6. The device according to claim 5, characterized in that, Each electrode is a tubular splicable electrode, whose material is metal. An external thread is provided at the top of each electrode, and an internal thread is provided at the bottom of each electrode. Two electrodes can be connected together by screwing the corresponding internal thread and external thread; A cable fixing bolt is provided on the side wall of each electrode for connecting and fixing the cable joint.

7. The device according to claim 6, characterized in that, The electrode is also equipped with an electrode cap. A lifting ring is provided at the top of the electrode cap for hoisting the electrode during construction. An internal thread corresponding to the external thread of the electrode is also provided inside the electrode cap for covering the top end of the electrode.

8. The device according to claim 5, characterized in that, The output voltage range of the isolation voltage regulator is 0 - 800V, and the maximum current load of each cable is 0 - 92A.

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