CN109188090A - The nonlinear test method of different humidity electric resistance of soil in vertical demixing soil - Google Patents
The nonlinear test method of different humidity electric resistance of soil in vertical demixing soil Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 192
- 238000010998 test method Methods 0.000 title claims abstract description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052802 copper Inorganic materials 0.000 claims abstract description 39
- 239000010949 copper Substances 0.000 claims abstract description 39
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- 230000002262 irrigation Effects 0.000 claims abstract description 14
- 238000003973 irrigation Methods 0.000 claims abstract description 14
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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Abstract
The nonlinear test method of different humidity electric resistance of soil in vertical demixing soil, including the nonlinear pilot system of different humidity electric resistance of soil in vertical demixing soil is built, system soil chamber interior wall is provided with drip irrigation appliance, and left and right side walls are provided with left and right copper electrode；Impulse current generator is connected to the high-voltage end of divider, and the high-voltage end of divider is connected to left copper electrode；Right copper electrode is connected to the ground terminal of impulse current generator；Further include insulating barrier, when insulating barrier is inserted into soil case, soil case is divided into multiple spaces from bottom to up；Filling soil simultaneously controls water content；Measure voltage and electric current of the pedotheque in current water content percentage accounting H；Assess electric resistance of soil nonlinear characteristic；Electric resistance of soil nonlinear characteristic under different humidity of testing and assessing.The present invention carries out vertical demixing to soil, can effective analogue ground system surrounding soil vertical demixing operating condition, accurate evaluation is carried out to vertical demixing electric resistance of soil nonlinear characteristic.
Description
Technical Field
The invention belongs to the technical field of power system grounding, and particularly relates to a method for testing the nonlinearity of resistance of soil with different humidity in vertically layered soil.
Background
When the power transmission line tower is struck by lightning, a very high potential can be generated on the tower body due to the existence of the tower grounding resistance, and the over-high potential can cause the tower to impact the power transmission line, so that the power transmission line is short-circuited, and the stability and the reliability of a power system are reduced. The main function of the grounding device of the transmission line tower is to effectively discharge lightning current into the ground when the tower top or the lightning conductor is struck by lightning, so that the current flowing through the grounding device is mainly lightning impulse current. The lightning current amplitude is large, so that local breakdown of soil around the grounding body is easy to occur, the conductivity of the soil is increased, the resistivity of the soil is reduced, and in addition, when the electric field intensity generated by the scattered current in the soil exceeds the critical breakdown field intensity of the soil, a spark discharge process similar to air breakdown can occur in the soil around the grounding body. The potential of each point on the grounding body and the potential difference between each point of the grounding body can be obviously reduced by the soil spark discharge, and the grounding device has obvious effects on reducing the tower top potential of a transmission line tower and the transient potential rise on a grounding grid of a power generation substation and a transformer substation.
Therefore, the research on the lightning impulse characteristics of the grounding device of the power transmission and distribution tower has important significance for establishing an advanced and reliable power transmission and distribution network and a power supply system in an intelligent power grid and perfecting a power grid safety guarantee and defense system.
Because the grounding electrode of the power transmission line tower is buried in the soil, the impact characteristic of the grounding electrode is closely related to the impact characteristic of the soil around the grounding body. At present, the domestic research on the nonlinear characteristics of soil resistance mainly simulates the dynamic ionization process and the spark discharge phenomenon of soil through computer simulation, and the nonlinear characteristics of the soil resistance under the impact current are influenced by a plurality of factors, such as: the impact current amplitude, soil composition and structure, soil density, moisture content, temperature, external electric field intensity and the like, which cause the nonlinear characteristics of the soil to become more complex when the high-frequency large impact current acts on the soil, wherein the soil moisture content often affects the nonlinear characteristics of the soil to a great extent, and the impact transient characteristics of the whole grounding system are greatly affected.
Disclosure of Invention
In order to accurately estimate the nonlinear characteristics of the soil, an intelligent measurement and control device is urgently needed to analyze and test the nonlinear characteristics of the soil resistance, and comprehensively consider the influences of soil humidity and vertical soil layering so as to evaluate the safety of a power transmission and distribution system. The invention aims to provide a nonlinear test method for soil resistance of different humidity in vertically layered soil, accurately establish a transient calculation model of a grounding body under the action of an impact current and provide theoretical support for effectively designing a grounding device.
The technical scheme for realizing the purpose of the invention is as follows:
the first step is as follows: constructing a nonlinear test system of the resistance of the soil with different humidity in the vertical layered soil, which comprises a soil box (06); a drip irrigation device (09) is arranged on the upper wall of the soil box (06); the left side wall of the soil box (06) is provided with a left copper electrode (05) and an operating mechanism (04) for controlling the left copper electrode (05) to move transversely; the right side wall of the soil box (06) is also provided with a right copper electrode (07); the left copper electrode (05) and the right copper electrode (07) are both circular and are vertically arranged; the left upper part, the right upper part, the left lower part and the right lower part of the soil box are respectively provided with a first humidity sensor (01a), a second humidity sensor (01b), a third humidity sensor (01c) and a fourth humidity sensor (01d),
wherein the first humidity sensor (01a), the second humidity sensor (01b), the third humidity sensor (01c) and the fourth humidity sensor (01d) are respectively connected to the input end of a moisture analyzer (14), and the output end of the moisture analyzer (14) is respectively connected to the digital controller (15) and the upper computer (18); the digital controller (15) is connected to the drip irrigation device (09);
the device also comprises a surge current generator (12) and a voltage divider (13), wherein the output end of the surge current generator (12) is connected to the high-voltage end of the voltage divider (13), and the high-voltage end of the voltage divider (13) is connected to the left copper electrode (05) through a high-voltage cable (19); the grounding end of the impulse current generator (12) and the right copper electrode (07) are also connected to the grounding device (11), and the grounding device (11) is grounded; the voltage measuring end of the voltage divider (13) is connected to the upper computer (18), and the grounding end is grounded; the test end of the current acquisition module (17) is connected to the copper wire (20) and is used for measuring the current flowing through the left copper electrode (05) and the right copper electrode (07);
the soil box also comprises more than one insulation partition plate (08), and the insulation partition plates (08) can be horizontally inserted into or drawn out of the soil box (06); when the insulating partition plate (08) is inserted into the soil box (06), the soil box (06) is divided into two or more spaces from the bottom to the top.
The second step is that: soil filling and controlling water content: opening an upper panel of the soil box (06), and controlling the distance between the left copper electrode (05) and the right copper electrode (07) through a control mechanism (04); according to the thickness ratio of the soil to be tested, the soil box (06) is layered by an insulating partition plate (08) and then is filled with a soil sample; removing the insulating partition (08) to enable the soil samples to be attached together; signals collected by the first humidity sensor (01a), the second humidity sensor (01b), the third humidity sensor (01c) and the fourth humidity sensor (01d) are transmitted to a moisture analyzer (14), the moisture content of a soil sample in the soil box (06) is monitored, and the moisture analyzer (14) calculates the average moisture content H1; setting the experimental water content H0, and if the average water content H1 is lower than the set water content H0, starting a drip irrigation device (09) through a digital controller (15) to uniformly and slowly inject distilled water into the soil, and controlling the total water content percentage H of the soil sample in the soil box (06) to be within the allowable error range of the set value H0.
The third step: measuring the voltage and the current of the soil sample when the current water content percentage is H: when the total water content percentage H of the soil sample is within the allowable error range of a set value H0, starting an impulse current generator (12), measuring the voltage between a left copper electrode (05) and a right copper electrode (07) through a voltage divider (13) and transmitting the voltage to an upper computer (18), measuring the current flowing through the left copper electrode (05) and the right copper electrode (07) through a current acquisition module (17) and transmitting the current to the upper computer (18);
the fourth step: evaluating the nonlinear characteristic of soil resistance: obtaining a voltage and current obtained by an upper computer to obtain an impulse resistance full time domain R (t) waveform curve, and extracting R (t)min，R(t)maxEffective ionization time t1And effective recovery time t2Calculating the average descending speed k of the soil under the impact current,
wherein R (t)minIs the minimum value of resistance in the R (t) waveform curve, R (t)maxIs the maximum value of resistance in the R (t) waveform curve, t1Denotes R (t) from the maximum value R (t)maxDown to a minimum value R (t)minThe time interval of (c);
calculation of R (t)minComposite evaluation factor q with k1：
Calculation of R (t)minAnd t1Composite judgment factor q of2：
Calculating a correction coefficient k1：
Wherein H is the percentage of water content and gamma is the minimum radius of curvature, calculated by the following formula:
wherein,
in the formula, tm∈[ta+0.1,tb)，taIs R (t)maxCorresponding time tbIs R (t)minCorresponding to the time, the above formula shows that the R (t) wave curve is calculated in the descending time period from taCalculating the curvature radius of each time at +0.1 time at intervals of 0.1 mus, and calculating the minimum curvature radius;
calculating judgment remainders:
q3＝0.01741log(0.424t1+0.391t2-40.11)
-0.0627log(R(t)min+1.322)
in the formula, t2Denotes R (t) from R (t)minResume to R (t)effThe time of (d); r (t)eff＝0.2R(t)min+0.8R(t)max；R(t)effCharacterization from R (t)minRestoration of 80% reduction (R (t)max-R(t)min) The resistance value of (1);
calculating the nonlinear characteristic evaluation factor q of the soil resistance of the soil under the impact voltage and the moisture content,
q＝k1(q1+q2)+q3
when q belongs to (0, 0.25), the nonlinear characteristic of the characteristic soil resistance is weak, when q belongs to (0.25, 0.65), the nonlinear characteristic of the characteristic soil resistance is general, when q belongs to (0.65, 0.9), the nonlinear characteristic of the characteristic soil resistance is strong, and when q belongs to (0.9, 1), the nonlinear characteristic of the characteristic soil resistance is strong.
The fifth step: soil resistance non-linear tests at different humidities: and (4) setting different humidity of the soil according to the test requirements, repeating the third step and the fourth step, and evaluating the nonlinear characteristic of the resistance of the vertically layered soil with different humidity.
The beneficial effect of the invention is that,
1) the soil is vertically layered, and the resistance nonlinearity of the vertically layered soil is measured, so that the vertical layering working condition of the soil around the grounding system can be effectively simulated;
2) the full-time-domain change waveform curve of the vertical stratification soil resistance under the action of the impact current can be effectively obtained, and the nonlinear characteristic of the vertical stratification soil resistance can be accurately evaluated by using the evaluation factor;
3) the main operation and control are completed by an upper computer, the accurate control of the moisture content of the vertically layered soil is realized by combining a digital controller and a drip irrigation device, and the nonlinear characteristic test of the resistance of the vertically layered soil with different moisture contents can be effectively carried out;
4) the experimental device is convenient to operate, safe and reliable, and has universality for testing vertical multilayer soil.
Drawings
FIG. 1 is a schematic view of the overall structure of a test system according to the present invention;
FIG. 2 is a schematic view showing the structure of a soil box according to the present invention;
FIG. 3 is a flow chart of the test method of the present invention;
FIG. 4 is a graphical illustration of a shock resistance full time domain variation waveform reflecting soil shock resistance non-linear characteristics.
Detailed Description
The invention will be further explained with reference to the drawings.
The first step is as follows: test system for building non-linearity of resistance of soil with different humidity in vertical layered soil
As shown in fig. 1 and fig. 2, a test system for testing the resistance nonlinearity of soil with different humidity in vertically layered soil is disclosed, which is used for simulating the resistance nonlinearity of vertically layered soil with different humidity, and mainly comprises a current collection module 17, an upper computer 18, a humidity analyzer 14, a high-voltage cable 19, a surge current generator 12, a grounding device 11, a high-voltage divider 13, a digital controller 15, an ac 220V power supply 16, a cable connector 03, a first humidity sensor 01a, a second humidity sensor 01b, a third humidity sensor 01c, a fourth humidity sensor 01d, a soil box 06, a drip irrigation device 09, an insulating partition 08, a left copper electrode 05, an operating mechanism 04, a right copper electrode 07 and a straight groove screw 02, wherein:
the current outflow end of the impulse current generator 12 is connected to the high-voltage end of the voltage divider 13, the left copper electrode 05 connected with the soil box 06 through the high-voltage cable 19, the right copper electrode 07 is connected with the grounding ends of the voltage divider 13 and the impulse current generator 12 through the high-voltage cable 19, the grounding ends are connected with the grounding device 11, when the impulse current generator 12 sends current, the voltage divider 13 measures voltage signals at two ends of the soil box 06, the current acquisition module 17 measures current signals flowing through the soil box 06 and transmits the current signals to the upper computer 18, and the nonlinear test and analysis of the soil resistance are realized on the upper computer.
The humidity sensors 01a, 01d, 01b and 01c collect signals which are transmitted to the humidity analyzer 14, the humidity analyzer 14 calculates average water content H1, the water content in the box is measured in real time, the water content values are fed back to the digital controller 15 and the upper computer 18 respectively, the water content of the device cannot be constant, therefore, the moisture content error is within +/-1%, the requirement is considered to be met, if the average water content H1 exceeds the upper limit of a set value, the drip irrigation device 09 is controlled to be disconnected through the digital controller 15, if the water content is lower than the lower limit of the set value, the drip irrigation device 09 is started through the digital controller 15, the water content in the soil box 06 is guaranteed to be within the error allowable range, the digital controller 15 is powered by an alternating current 220V power supply 16, and the internal water content of the soil box 06 is adjusted through the control device 09 with the.
The soil sample is vertically layered through an insulating partition plate 08, and the interface of each layer of soil in the soil box 06 is parallel to the upper surface and the lower surface of the soil box 06; the number of layers is the limited number of layers of actual soil, and if the actual soil is divided into 3 layers, each layer is limited in thickness, the thickness ratio of the soil can be obtained, the insulating partition 08 separates the soil in the soil box 06 according to the thickness ratio in the direction parallel to the surface of the electrode, and after the soil sample is filled, the insulating partition 08 is drawn out, and each layer of soil is tightly attached.
The second step is that: soil filling and humidity setting of soil box
The upper panel of the soil box 06 is opened, the distance between the left copper electrode 05 and the right copper electrode 07 is controlled through the control mechanism 04, the soil box 06 is vertically layered by the insulating partition 08 according to the thickness ratio of actual soil, a soil sample is filled, and then the insulating partition 08 is removed, so that different layers of soil are tightly attached.
If the soil in a certain area is vertically layered, the thickness of the first layer of soil is 12m, the soil resistivity is 500 omega m, the thickness of the second layer of soil is 24m, the soil resistivity is 1000 omega m, the thickness of the third layer of soil is 40m, the soil resistivity is 500 omega m, and a soil area with infinite thickness is arranged outside the third layer; the thickness ratio of the vertically stratified soil is 12: 24: and 40, setting the distance between the upper inner surface and the lower inner surface of the soil box as L, dividing the distance according to the thickness ratio, layering the distance by using an insulating partition plate 08, putting a soil sample into the soil box, and setting the resistivity of each layer of the soil sample to be the same as the resistivity of the actual soil layer.
The panel is covered and the slotted screw 02 is screwed. The method comprises the steps of turning on an alternating current 220V power supply 16 and humidity sensors 01a, 01b, 01c and 01d, transmitting collected signals to a humidity analyzer 14, monitoring the moisture content in a soil box 06, feeding the moisture content value back to a digital controller 15 and an upper computer 18 respectively, disconnecting a drip irrigation device 09 if the moisture content exceeds a set moisture content H0, starting the drip irrigation device 09 if the moisture content is lower than a set moisture content H0, and uniformly injecting distilled water into soil, so that the moisture content of the soil filled in the soil box 06 is controlled to be stabilized near H0 (+ -1%).
The third step: voltage signals at two ends of soil box and current signals flowing through soil box when different water contents are measured
Through the first step, soil is filled, the first humidity sensor 01a, the second humidity sensor 01b, the third humidity sensor 01c and the fourth humidity sensor 01d are all stabilized at a set water content H0, the impact current generator 12 is turned on to emit current, the voltage divider 13 measures voltage signals at two ends of the soil box 06, the current acquisition module 17 measures current signals flowing through the soil box 06 and transmits the current signals to the upper computer 18; then, the digital controller 15 and the upper computer 18 are used for controlling the drip irrigation device 09 to be switched on and off so as to change the water content of the soil box 06, and the voltage signal and the current signal are repeatedly measured.
The fourth step: assessing soil resistance nonlinearity
The voltage and current waveform obtained by the upper computer can obtain an impact resistance full time domain R (t) waveform curve, and extract R (t)min(in units of. omega., R (t))max(in Ω), effective ionization time t1(in μ s) and effective recovery time t2(in μ s) and the average rate of fall k of the soil at the impact current was calculated.
In the formula R (t)min(in Ω) is the minimum resistance in the curve R (t), R (t)max(in Ω) is the maximum resistance in the R (t) waveform curve, t1Denotes R (t) from the maximum value R (t)maxDown to a minimum value R (t)minThe time interval of (c).
Step 1: calculation of R (t)minComposite evaluation factor q with k1：
Step 2: calculation of R (t)minAnd t1Composite judgment factor q of2：
And step 3: calculating a correction coefficient k1：
Wherein H is the percentage of water content and gamma is the minimum radius of curvature, calculated by the following formula:
wherein,
in the formula, tm∈[ta+0.1,tb)，taIs R (t)maxCorresponding time tbIs R (t)minCorresponding to the time, the above formula shows that the R (t) wave curve is calculated in the descending time period from taCalculating the curvature radius of each time at +0.1 time at intervals of 0.1 mus, and calculating the minimum curvature radius;
and 4, step 4: computing and judging remainder q3：
q3＝0.01741log(0.424t1+0.391t2-40.11)
-0.0627log(R(t)min+1.322)
In the formula, t2(in. mu.s) denotes R (t) from R (t)minResume to R (t)effTime of (d). Wherein R (t)eff＝0.2R(t)min+0.8R(t)max,R(t)effCharacterization from R (t)minRestoration of 80% reduction (R (t)max-R(t)min) The resistance value of (2).
And 5: calculating a resistance nonlinear evaluation factor q of the soil under the impact voltage and the humidity:
q＝k1(q1+q2)+q3
when q belongs to (0, 0.25), the nonlinear characteristic of the characteristic soil resistance is weak, when q belongs to (0.25, 0.65), the nonlinear characteristic of the characteristic soil resistance is general, when q belongs to (0.65, 0.9), the nonlinear characteristic of the characteristic soil resistance is strong, and when q belongs to (0.9, 1), the nonlinear characteristic of the characteristic soil resistance is strong.
The fifth step: test of nonlinear characteristic of soil resistance under different humidity
And (4) setting different humidity of the soil, namely different water content, according to the test requirements, repeating the third step and the fourth step, and performing nonlinear characteristic evaluation on the resistance of the vertical stratified soil under different humidity. If H2 and H3 vertical stratification soil resistance nonlinearity needs to be tested, after the H1 test is finished, setting the set water content of the moisture analyzer 14 to be H2 at intervals, repeating the third and fourth steps, testing the soil dynamic resistance nonlinearity of H2, and after the intervals are finished, testing the soil resistance nonlinearity under H3.
Claims (1)
1. The test method for the nonlinearity of the resistance of the soil with different humidity in the vertically layered soil is characterized by comprising the following steps,
the first step is as follows: constructing a nonlinear test system of the resistance of the soil with different humidity in the vertical layered soil, which comprises a soil box (06); a drip irrigation device (09) is arranged on the upper wall of the soil box (06); the left side wall of the soil box (06) is provided with a left copper electrode (05) and an operating mechanism (04) for controlling the left copper electrode (05) to move transversely; the right side wall of the soil box (06) is also provided with a right copper electrode (07); the left copper electrode (05) and the right copper electrode (07) are both circular and are arranged in the vertical direction; the left upper part, the right upper part, the left lower part and the right lower part of the soil box are respectively provided with a first humidity sensor (01a), a second humidity sensor (01b), a third humidity sensor (01c) and a fourth humidity sensor (01 d);
the humidity monitoring system comprises a first humidity sensor (01a), a second humidity sensor (01b), a third humidity sensor (01c) and a fourth humidity sensor (01d), wherein the first humidity sensor (01a), the second humidity sensor (01b), the third humidity sensor (01c) and the fourth humidity sensor (01d) are respectively connected to the input end of a moisture analyzer (14), and the output end of the moisture analyzer (14) is respectively connected to a digital controller (15) and an upper computer (18); the digital controller (15) is connected to the drip irrigation device (09);
the device also comprises a surge current generator (12) and a voltage divider (13), wherein the output end of the surge current generator (12) is connected to the high-voltage end of the voltage divider (13), and the high-voltage end of the voltage divider (13) is connected to the left copper electrode (05) through a high-voltage cable (19); the grounding end of the impulse current generator (12) and the right copper electrode (07) are also connected to the grounding device (11), and the grounding device (11) is grounded; the voltage measuring end of the voltage divider (13) is connected to the upper computer (18), and the grounding end is grounded; the current acquisition module (17) is connected to the upper computer (18), and the test end of the current acquisition module (17) is connected to the copper wire (20) and used for measuring the current flowing through the left copper electrode (05) and the right copper electrode (07);
the soil box also comprises an upper insulating partition plate (08), and the insulating partition plate (08) can be horizontally inserted into or pulled out of the soil box (06); when the insulating partition plate (08) is inserted into the soil box (06), the soil box (06) is divided into two or more spaces from the bottom to the top.
The second step is that: soil filling and controlling water content: opening an upper panel of the soil box (06), and controlling the distance between the left copper electrode (05) and the right copper electrode (07) through a control mechanism (04); according to the thickness ratio of the soil to be tested, the soil box (06) is layered by an insulating partition plate (08) and then is filled with a soil sample; removing the insulating partition (08) to enable the soil samples to be attached together; signals collected by the first humidity sensor (01a), the second humidity sensor (01b), the third humidity sensor (01c) and the fourth humidity sensor (01d) are transmitted to a moisture analyzer (14), the moisture content of a soil sample in the soil box (06) is monitored, and the moisture analyzer (14) calculates the average moisture content H1; setting an experimental water content H0, if the average water content H1 is lower than the set water content H0, starting a drip irrigation device (09) through a digital controller (15) to uniformly and slowly inject distilled water into the soil, and controlling the total water content percentage H of the soil sample in a soil box (06) to be within an allowable error range of a set value H0;
the third step: measuring the voltage and the current of the soil sample when the current water content percentage is H: when the total water content percentage H of the soil sample is within the allowable error range of a set value H0, starting an impulse current generator (12), measuring the voltage between a left copper electrode (05) and a right copper electrode (07) through a voltage divider (13) and transmitting the voltage to an upper computer (18), measuring the current flowing through the left copper electrode (05) and the right copper electrode (07) through a current acquisition module (17) and transmitting the current to the upper computer (18);
the fourth step: evaluating the nonlinear characteristic of soil resistance: obtaining a full time domain R (t) waveform curve of the impulse resistance through the voltage and the current obtained by the upper computer, and extracting R (t) min, R (t) max and effective ionization time t1And effective recovery time t2Calculating the average descending speed k of the soil under the impact current,
wherein R (t)minIs the minimum value of resistance in the R (t) waveform curve, R (t)maxIs the maximum value of resistance in the R (t) waveform curve, t1Denotes R (t) from the maximum value R (t)maxDown to a minimum value R (t)minThe time interval of (c);
calculation of R (t)minComposite evaluation factor q with k1：
Calculation of R (t)minAnd t1Composite judgment factor q of2：
Calculating a correction coefficient k1：
Wherein H is the percentage of water content and gamma is the minimum radius of curvature, calculated by the following formula:
wherein,
in the formula, tm∈[ta+0.1,tb)，taIs R (t)maxCorresponding time tbIs R (t)minCorresponding to the time, the above formula shows that the R (t) wave curve is calculated in the descending time period from taCalculating the curvature radius of each time at +0.1 time at intervals of 0.1 mus, and calculating the minimum curvature radius;
calculating judgment remainders:
q3＝0.01741log(0.424t1+0.391t2-40.11)
-0.0627log(R(t)min+1.322)
in the formula, t2Denotes R (t) from R (t)minResume to R (t)effThe time of (d); r (t)eff＝0.2R(t)min+0.8R(t)max，R(t)effCharacterization from R (t)minRestoration of 80% reduction (R (t)max-R(t)min) The resistance value of (1);
calculating the nonlinear characteristic evaluation factor q of the soil resistance of the soil under the impact voltage and the moisture content,
q＝k1(q1+q2)+q3
when q belongs to (0, 0.25), the nonlinear characteristic of the characteristic soil resistance is weak, when q belongs to (0.25, 0.65), the nonlinear characteristic of the characteristic soil resistance is general, when q belongs to (0.65, 0.9), the nonlinear characteristic of the characteristic soil resistance is strong, and when q belongs to (0.9, 1), the nonlinear characteristic of the characteristic soil resistance is strong.
The fifth step: soil resistance non-linear tests at different humidities: and setting different humidity of the soil according to test requirements, repeating the third step and the fourth step, and evaluating the nonlinear characteristic of the dynamic resistance of the horizontal stratum soil under different humidity.
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