Method for evaluating contribution rate of conductive path to saturated soil conductivity
By establishing a saturated soil conductivity model of mixed soil, the contribution of the conductive path to the conductivity of saturated soil is solved, and the problem of inability to evaluate the contribution of the conductive path in the existing technology is solved, and the conductivity under different conditions is achieved Quantitative study of changing trends.
Patent Information
- Application Number
- CN202411229576.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2024-12-31
AI Technical Summary
The prior art cannot effectively evaluate the contribution of conductive paths to the conductivity of saturated soil, especially the influence of the conductivity and porosity conditions of different pore fluids, which makes it difficult to achieve quantitative research on the microstructure changes of clay soils.
A saturated soil conductivity model of mixed soils was established, including parallel conductive paths at the same depth. By measuring and calculating the conductive path contribution rate at different pore fluid conductivity and porosity, the model parameters were fitted using formulas to obtain conductivity. The contribution rate of paths to the conductivity of saturated soils.
The quantitative evaluation of the contribution of multiple conductive paths to the conductivity of saturated mixed soil under different conditions is achieved, providing an important basis for the changes in the fine structure of the soil inside.
Smart Images
Figure CN119230004A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of rock and soil mechanics and engineering, and specifically relates to a method for evaluating the contribution rate of a conductive path to the electrical conductivity of a saturated soil. The method is applicable to, but not limited to, testing the contribution of a conductive path in saturated clay to the electrical conductivity of the saturated soil under different conditions, so as to assist in characterizing the microstructure state of the soil. Background Art
[0002] Soil resistivity is a measure of the degree to which soil blocks the current in the soil. It is one of the basic properties of soil. Soil conductivity is the reciprocal of soil resistivity. Soil conductivity is related to soil composition (particle size distribution, mineralogy), pore structure (porosity, pore distribution and connectivity), water content, and temperature. In order to understand the characteristics of oil and gas reservoirs in rock matrices, Archie (1942) proposed Archie's law, which correlated the resistivity of sandstone with the resistivity of pore fluid, but did not consider the role of surface charge in the conductivity of clay soil; Waxman (1968) et al. proposed a double parallel resistance model, which correlated the conductivity of saturated mudstone with the surface conductivity and pore fluid conductivity, but the model did not consider the joint influence of the surface conductivity and pore fluid conductivity in series; Rhoades (1989) et al. proposed a three-path current flow model for soil conductivity, which assumes that in addition to the paths in the two parallel resistance models, there is also a path in series with the flow along the particle surface and the flow of pore fluid. However, the model focuses on how to fit the data well over the full range of pore fluid conductivity, and does not fully consider the contribution of the conductive path to the overall soil conductivity.
[0003] In cohesive mixed soils, which path is the most important contributing path to the mixed soil conductivity and how the contribution of the conductive path varies with the changes in pore fluid conductivity and different porosities remains a knowledge gap, and it is impossible to quantitatively evaluate the impact of the conductive path on the conductivity of saturated soils under different pore fluid conductivity or different porosity conditions. Summary of the invention
[0004] The object of the present invention is to provide a method for evaluating the contribution rate of a conductive path to the electrical conductivity of a saturated soil body in view of the above-mentioned problems existing in the prior art.
[0005] The above-mentioned purpose of the present invention is achieved by the following technical means:
[0006] A method for evaluating the contribution of conductive paths to the electrical conductivity of saturated soil comprises the following steps:
[0007] Step 1: Establish the saturated soil conductivity model of mixed soil.
[0008] The soil conductivity model consists of parallel conductive paths P at the same depth.u , conductive path P s , conductive path P w and an air path, wherein the conductive path P u The first solid particle module and the first pore fluid module are sequentially included from top to bottom in the depth direction, and the conductive path P s For the second solid particle module, the conductive path P w is a second pore fluid module, and the air path is an air module;
[0009] Step 2: Configure the same porosity n and different pore fluid conductivity σ w Various mixed soils;
[0010] Step 3: Measure the conductivity σ of pore fluids with the same porosity n and different pore fluid conductivity σ w The electrical conductivity of the mixed soil corresponding to each mixed soil is σ0, and then the pore fluid conductivity σ w and porosity n, calculate the conductivity σ of the first solid particle module and the second solid particle module s ,
[0011]
[0012] Among them, σ w is the conductivity of the first pore fluid module and the second pore fluid module, CF is the clay content in the mixed soil, G s1 is the specific gravity of clay in the mixed soil, G s2 is the proportion of sand in the mixed soil. is the mass density of water at 4°C, n is the porosity of the mixed soil, CEC is the cation exchange capacity,
[0013] Step 4: According to different pore fluid conductivity σ w And the corresponding conductivity σ0, fit the following formula to obtain σ s and L w ,
[0014]
[0015] According to L u ·L' w +L w =n,L u +L s +L w =1, get L u , L s , L' w , according to L' s +L' w =1, obtain L' s ,
[0016] Among them, L u is the cross-sectional width of the first solid particle module and the first pore fluid module, L w is the cross-sectional width of the second pore fluid module, L' w is the depth of the first pore fluid module, L s is the cross-sectional width of the second solid particle module, L' s is the depth of the first solid particle module;
[0017] Step 5: Calculate the conductive path P u , P s , P w Contribution to the electrical conductivity of saturated soil,
[0018]
[0019]
[0020]
[0021] In the formula, CP u is the conductive path P u Contribution to the electrical conductivity of saturated soil, CP s is the conductive path P s Contribution to the electrical conductivity of saturated soil, CP w is the conductive path P w Contribution rate to the electrical conductivity of saturated soil.
[0022] A method for evaluating the contribution of conductive paths to the electrical conductivity of saturated soil, further comprising step 6: changing the porosity n, and repeating steps 2-5 to analyze the contribution of P under different porosity n. u , P s , P w The contribution rate and changing trend of the conductive path to the electrical conductivity of saturated soil.
[0023] As described above, when the clay content CF in the mixed soil is ≤30%, the method for preparing the mixed soil includes the following steps:
[0024] Clay and sand with set clay content CF are placed in flasks respectively and mixed with salt solution. The clay slurry and sand slurry in the flask are boiled to degas. After cooling, the clay slurry is poured into a cylindrical preparation tube. After the clay slurry settles to the bottom of the preparation tube, the sand slurry is poured in. The preparation tube is sealed and rotated to mix evenly, and then poured into the consolidator to consolidate to obtain a uniform mixed soil body without segregation.
[0025] As described above, when the clay content CF in the mixed soil is ≥ 40% and the clay content in the mixed soil is 30% < CF < 40%, the preparation method of the mixed soil includes the following steps:
[0026] After mixing clay and sand according to the clay content CF, and then mixing with a salt solution at a predetermined water content and mixing evenly, pour it into a consolidometer and consolidate to obtain the mixed soil.
[0027] As described above, the salt solution is a sodium chloride solution.
[0028] As described above, a conductive sheet for measuring the conductivity σ0 of the mixed soil is provided in the consolidation chamber of the consolidometer.
[0029] The present invention has the following beneficial effects compared with the prior art:
[0030] A saturated soil conductivity model is established, and a contribution equation for the conduction path is proposed. The contribution size and change trend of the conduction path to the conductivity of the fully saturated mixed soil under multiple different conditions can be obtained through one implementation; at the same time, experiments can also be carried out under conditions such as different particle size distributions of the test objects, different saturated soil mixed with clay test objects, different pore fluid conductivities, different porosities, and different clay contents, to obtain the contribution rate size and change trend of the conduction path, which can provide an important basis for quantitatively studying the changes in the fine and microscopic structure inside the saturated soil. Description of the Drawings
[0031] Figure 1 is a flowchart of the present invention;
[0032] Figure 2 is a graph of the size and change trend of the contribution rate of the conduction path to the conductivity of the saturated soil when the porosity n is 0.41 and the pore fluid conductivity σ w is 0.013, 0.038, 0.061, 0.119, 0.234, 1.064, 2.043, 3.356 respectively; u P s P w is a graph of the size and change trend of the contribution rate of the conduction path to the conductivity of the saturated soil;
[0033] Figure 3 is a graph of the size and change trend of the contribution rate of the conduction path to the conductivity of the saturated soil when the pore fluid conductivity σ w is 3.356 and the porosity n is 0.41, 0.46, 0.50, 0.53, 0.56 respectively; u P s P w is a graph of the size and change trend of the contribution rate of the conduction path to the conductivity of the saturated soil;
[0034] Figure 4is the parallel conductive path P at the same depth in the soil conductivity model u , conductive path P s , conductive path P w and a stereogram of the air path. DETAILED DESCRIPTION
[0035] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below with reference to examples. The implementation examples described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.
[0036] Embodiment 1:
[0037] A method for evaluating the contribution of conductive paths to the electrical conductivity of saturated soil comprises the following steps:
[0038] Step 1, establishing a saturated soil conductivity model for mixed soil;
[0039] The soil conductivity model is determined as follows:
[0040] According to the Rhoades hypothesis mentioned in the background technology, there are three conductive paths in the mixed soil to establish the soil conductivity model of the mixed soil;
[0041] like Figure 4 As shown in Figure 2, the soil conductivity model includes parallel conductive paths P at the same depth. u , conductive path P s , conductive path P w and an air path, wherein the conductive path P u The first solid particle module and the first pore fluid module are sequentially included from top to bottom in the depth direction, and the conductive path P s For the second solid particle module, the conductive path P w is the second pore fluid module, and the air path is the air module.
[0042] like Figure 4 As shown, the conductive path P u , conductive path P s , conductive path P w The depth of the air path is the same as that of the soil conductivity model, and the conductive path P u , conductive path P s , conductive path P w The sum of the cross-sectional widths of the conductive path P and the air path P is the cross-sectional width of the soil conductivity model. u , conductive path P s , conductive path P w and the cross-sectional length of the air path is the same as the cross-sectional length of the soil conductivity model, Lu is the cross-sectional width of the first solid particle module and the first pore fluid module, L s is the cross-sectional width of the second solid particle module, L w is the cross-sectional width of the second pore fluid module, L a is the cross-sectional width of the air module, L' s is the depth of the first solid particle module, L' w is the depth of the first pore fluid module, the depth of the second solid particle module, the second pore fluid module and the air module are all L' s +L' w In this embodiment, it is assumed that L u +L s +L w +L a =1,L' s +L' w =1, the cross-sectional lengths of the first solid particle module, the first pore fluid module, the second solid particle module, the second pore fluid module and the air module are all 1.
[0043] According to the equivalent circuit of mixed soil and Ohm's law, the expression of the total resistance R0 of the soil can be obtained as follows:
[0044]
[0045] Where R0 is the total resistance of the mixed soil, R w is the resistance of the second pore fluid module, R s is the resistance of the second solid particle module, R' s is the resistance of the first solid particle module, R' w The resistance of the first pore fluid module, R a is the resistance of air. When the soil is fully saturated, 1 / R a Close to zero.
[0046] The relationship between resistance R and resistivity ρ is as follows:
[0047]
[0048] Where R is the resistance, ρ is the resistivity, l is the height of the mixed soil after consolidation, and A is the cross-sectional area of the mixed soil after consolidation.
[0049] Combining the expression of the total resistance R0 of the soil, i.e., equation (1), and the relationship between resistance R and resistivity ρ, i.e., equation (2), the expression of the resistivity of the mixed soil is obtained as follows:
[0050]
[0051] Where ρ0 is the resistivity of the mixed soil, ρ s is the resistivity of the first solid particle module and the second solid particle module, ρ w is the resistivity of the first pore fluid module and the second pore fluid module.
[0052] Conductivity σ is the reciprocal of resistivity ρ, that is, σ0 = 1 / ρ0, σ s =1 / ρ s , σ w =1 / ρ w , substituting into formula (3), we get the expression of saturated soil conductivity of mixed soil as formula (4):
[0053]
[0054] Where σ0 is the saturated soil conductivity of the mixed soil, that is, the conductivity of the mixed soil, σ s is the conductivity of the first solid particle module and the second solid particle module, that is, the solid particle conductivity of the mixed soil, σ w It is the conductivity of the first pore fluid module and the second pore fluid module, that is, the pore fluid conductivity of the mixed soil.
[0055] Mixed soil conductivity model parameter L u , L s , L w , L' w , L' s The method of determining is as follows:
[0056] Through experimental measurement, it is found that when σ w >0.234S / m, L u , L s With σ w The increase of remains basically unchanged, then formula (4) can be derived as follows:
[0057]
[0058] Based on the above derivation, formula (4) is transformed into formula (5):
[0059]
[0060] In the formula, σ w is the independent variable, σ0 is the dependent variable, and multiple pore fluid conductivity σ w Mixed soil, and then measure each σ w The corresponding mixed soil conductivity σ0 is used to fit a straight line. The slope of the straight line fitted by formula (5) is σ s is the intercept of the straight line fitted by equation (5) on the σ0 axis.
[0061] According to the definition of porosity n and saturation, we can get:
[0062] L u ·L' w +L w =n (6)
[0063] When the soil is fully saturated, L u , L s , L w The relationship between them is as shown in formula (7):
[0064] L u +L s +L w =1 (7)
[0065] The conductivity σ of the first solid particle module and the second solid particle module s and surface cation mobility B and ion concentration Q v Connect them as formula (8):
[0066] σ s =BQ v (8)
[0067] Where B is the mobility of surface cations, which can be calculated by formula (9):
[0068] B=0.046·[1-0.6·exp(-σ w / 0.013)] (9)
[0069] In formula (8), Q v is the ion concentration per unit pore volume and can be expressed as a function of the cation exchange capacity CEC, as shown in formula (10):
[0070]
[0071] Where D p is the mass density of the first solid particle module and the second solid particle module, D p It can be calculated by the following formula (11):
[0072]
[0073] Where CF is the clay content in the mixed soil (the weight of clay divided by the total weight of the mixed soil), G s1 is the specific gravity of clay in the mixed soil, G s2 It is the specific gravity of sand in the mixed soil. The specific gravity can be measured in the laboratory by the pycnometer method. is the mass density of water at 4°C.
[0074] Combining equations (8), (9), (10) and (11), we can obtain the conductivity σ of the first solid particle module and the second solid particle module: s The expression of is as follows:
[0075]
[0076] In the formula, σ s is the conductivity of the first solid particle module and the second solid particle module, σ w is the conductivity of the first pore fluid module and the second pore fluid module, CF is the clay content in the mixed soil, G s1 is the specific gravity of clay in the mixed soil, G s2 is the proportion of sand in the mixed soil. is the mass density of water at 4°C, n is the porosity of the mixed soil, and CEC is the cation exchange capacity.
[0077] In the formula, σ w , CF, G s1 , G s2 The mixed soil is prepared according to the requirements. n, CEC is measured according to the experiment, then σ s It can be obtained.
[0078] Step 2: Configure the same porosity n and different pore fluid conductivity σ w Various mixed soils;
[0079] Step 3: Measure the conductivity σ of pore fluids with the same porosity n and different pore fluid conductivity σ w The electrical conductivity of the mixed soil corresponding to each mixed soil is σ0, and then the pore fluid conductivity σ w and porosity n, calculate σ according to formula (12) s ;
[0080] Step 4: According to different pore fluid conductivity σ w and the corresponding conductivity σ0, and the intercept is obtained by fitting the straight line using formula (5) σ s and slope L w ; Combine equation (6) and equation (7) to obtain the model parameter L u , L s , L' w , according to the relation L' s +L' w =1, we can get L' s , so that all model parameters L are obtained u , L s , L w , L' w , L' s ;
[0081] Step 5: Use the pore fluid conductivity σ w and the corresponding mixed soil conductivity σ0, mixed soil solid particle conductivity σ s , model parameter L u , L s , L w , L' w , L' s , according to P u , P s , P w The contribution model of conductive path to saturated soil conductivity is used to obtain the contribution rate;
[0082] According to the first term in formula (4) The second term L is associated with the conductivity of the first solid particle and the first pore fluid in series. s σ s Associated with the second solid particles that are in close enough contact with each other, the third term L w σ w Associated with the second pore fluid conductivity, define P u , P s , P w The contribution model of conductive path to saturated soil conductivity is as follows:
[0083]
[0084] In the formula, CP u YesP u Contribution of conductive path to saturated soil conductivity, CP s YesP s Contribution of conductive path to saturated soil conductivity, CP w YesP w Contribution of conductive paths to the electrical conductivity of saturated soil;
[0085] Step 6: Change the porosity n and repeat steps 2-5 to analyze the conductivity σ of different pore fluids w And P under different porosity n u , P s , P w The contribution rate and changing trend of the conductive path to the electrical conductivity of saturated soil.
[0086] Embodiment 2:
[0087] Using the method described in Example 1 to evaluate the contribution of the conductive path to the conductivity of saturated soil, taking kaolin-sand mixed soil as an example, combined with electrical tests, the conductivity σ of different pore fluids was obtained. w, and the contribution rate of the conductive path to the electrical conductivity σ0 of the kaolin-sand mixed soil under the condition of different porosities n. The specific implementation process is as follows:
[0088] Step 1: Establish a saturated soil electrical conductivity model for the mixed soil in the same way as in Example 1;
[0089] Step 2: In the same way as step 2 in Example 1, prepare each mixed soil with the same porosity n and different pore fluid electrical conductivities σ w . In this example, kaolin is taken as an example of clay to make kaolin-sand mixed soil, and the clay content (CF = clay weight / total weight of clay + sand) is controlled to be the same. In this example, the clay content is 60%.
[0090] The parameters of kaolin and sand are as follows:
[0091] The average specific gravity of kaolin is 2.52, the particle size is less than 0.075 mm, the coefficient of uniformity is 6.51, and the characteristic particle size d 50 is 0.004 mm, and the liquid limit and plastic limit are 36.4% and 23.6% respectively. The specific gravity of sand is 2.65, the coefficient of uniformity is 1.52, the characteristic particle size d 50 is 0.470 mm, and the maximum and minimum porosities are 1.04 and 0.66 respectively.
[0092] The preparation methods of low clay content mixed soil (CF ≤ 30%), high clay content mixed soil (CF ≥ 40%), and mixed soil with clay content of 30% < CF < 40% are as follows:
[0093] The low clay content mixed soil (CF ≤ 30%) is prepared by the slurry deposition method. Kaolin and sand are respectively placed in flasks and mixed with the test salt solution (such as sodium chloride solution), boiled for 15 minutes to degas the kaolin slurry and sand slurry in the flasks. After cooling, pour the kaolin slurry into a cylindrical preparation tube. When the kaolin slurry settles to the bottom of the preparation tube, pour the sand slurry into it, seal the preparation tube and rotate it vigorously for 20 minutes. After mixing evenly, pour it into an oedometer to consolidate and obtain a uniform and non-segregating low clay content mixed soil;
[0094] The mixed soil with clay content of 30% < CF < 40% and the high clay content mixed soil (CF ≥ 40%) are prepared by the slurry mixing method. The soil body obtained by mixing kaolin and sand according to the clay content CF is mixed evenly with the test salt solution (such as sodium chloride solution) at a predetermined water content, and then poured into an oedometer to consolidate and obtain a high clay content mixed soil;
[0095] As a preferred method, the consolidation chamber is made of non-conductive material, such as plexiglass. A conductive sheet with a conductive wire welded to it can be attached to the consolidation chamber, and the conductive wire can be led out of the consolidation chamber. This not only facilitates the subsequent measurement of the electrical conductivity σ0 of the mixed soil, but also avoids taking the consolidated mixed soil out of the consolidation chamber and avoiding the deformation of the shape of the consolidated mixed soil after taking it out, which will affect the accuracy of the measurement data, thereby ensuring the accuracy of the measurement data.
[0096] The pore fluid conductivity traversal step is implemented. In this embodiment, the clay content is controlled to be a fixed value of 60%, and the pore fluid conductivity σ is prepared. w The mixed soils are 0.013, 0.038, 0.061, 0.119, 0.234, 1.064, 2.043 and 3.356 respectively. These eight mixed soils are consolidated to the same height in an instrumented consolidation meter. The cross-sectional area after consolidation is the cross-sectional area of the consolidation meter, thus obtaining mixed soils with the same porosity n.
[0097] The mixed soil is consolidated to the same height, i.e., corresponding to l in formula (2) in Example 1. The cross-sectional area of the consolidator is fixed, i.e., the cross-sectional areas of all the mixed soils are the same, corresponding to A in formula (2) in Example 1. This ensures that the volumes of all the mixed soils are the same, i.e., the porosity n is the same.
[0098] Step 3, same as step 3 in Example 1, measuring the conductivity σ of the pore fluid with the same porosity n and different pore fluids w The mixed soil conductivity σ0 corresponding to each mixed soil.
[0099] The measurement method of mixed soil conductivity σ0 is as follows:
[0100] The conductivity σ0 of the mixed soil is measured using an instrumented consolidation meter and an LCR meter (L is inductance, C is capacitance, and R is resistance). The consolidation chamber is made of a non-conductive material (such as plexiglass). In this embodiment, four electrodes are provided in the consolidation chamber for connecting the LCR meter, and the size of the consolidation chamber is Φ100mm×87mm. During the test, the current flows between the high current electrode and the low current electrode, and the resistance of the high potential electrode and the low potential electrode is measured using the LCR meter. After the LCR meter obtains the resistance of the mixed soil, it converts the mixed soil conductivity σ0 according to the relationship between the resistance and conductivity of the mixed soil.
[0101] Step 4: σ s The pore fluid conductivity σ of the configured mixed soil is used w and porosity n, calculated according to formula (12) in Example 1; and then using eight different pore fluid conductivity σ w and the measured electrical conductivity σ0 of the corresponding mixed soil, a straight line is fitted according to equation (5) of Example 1, L wis the slope of the fitted straight line, σ s is the intercept of the fitted straight line on the σ0 axis; L u , L s , L' w Use formula (6) and formula (7) in Example 1 to obtain; L' s Using the relation L' in Example 1 s +L' w =1 to obtain.
[0102] Step 5: Use the pore fluid conductivity σ w and the corresponding mixed soil conductivity σ0, the contribution rate is obtained according to formula (13) in step 5 of Example 1, and the contribution rate is analyzed at different pore fluid conductivity σ w Under the condition of P u , P s , P w The contribution rate of the conductive path to the conductivity of saturated soil and its changing trend are shown in Figure 2 .
[0103] Step 6: Same as step 6 of Example 1, changing the porosity n, so as to analyze the P under different porosity n conditions. u , P s , P w The contribution rate and changing trend of the conductive path to the electrical conductivity of saturated soil.
[0104] The porosity traversal step is implemented. In this embodiment, the consolidation porosity n is 0.41, 0.46, 0.50, 0.53, and 0.56, and the pore fluid conductivity traversal step is implemented respectively. Then, steps 2-5 in embodiment 1 are repeated, and finally the pore fluid conductivity σ is selected. w The same mixed soil is used to explore the contribution rate and change trend of the conductive path to the conductivity of the mixed soil under different porosity n conditions. Figure 3 is the pore fluid conductivity σ w When the porosity n is 0.41, 0.46, 0.50, 0.53, and 0.56, the P u , P s , P w The contribution rate and changing trend of the conductive path to the electrical conductivity of saturated soil.
[0105] Embodiment 3:
[0106] The clay content CF in step 2 of Example 2 is replaced by 0%, 20%, 40%, 80%, 100%, and the pore fluid conductivity σ wThe test was conducted in the range of 0.013-0.356 S / m and consolidated to the same porosity n, and steps 1 to 6 of Example 2 were repeated to obtain the contribution rate and change trend of the conductive path to the saturated soil conductivity under different clay contents CF.
[0107] Embodiment 4:
[0108] By using different particle gradations for the kaolin-sand mixed soil in step 2 of Example 2 and repeating steps 1 to 6 of Example 2, the contribution rate and variation trend of the conductive path to the saturated soil conductivity under soil conditions with different particle gradations can be obtained.
[0109] Embodiment 5:
[0110] Replace the kaolin-sand mixed soil in step 2 of Example 2 with other saturated clay-sand mixtures, and repeat steps 1 to 6 of Example 2 to obtain the contribution rate and change trend of the conductive path to the electrical conductivity of the saturated soil under different saturated mixed soil conditions.
[0111] It should be noted that the specific embodiments described in the present invention are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.
Claims
1. A method for evaluating the contribution of conductive paths to the electrical conductivity of saturated soil, characterized in that: Including the following steps: Step 1, establish a saturated soil conductivity model for the mixed soil. The soil conductivity model consists of parallel conductive paths P at the same depth. u , conductive path P s , conductive path P w and an air path, wherein the conductive path P u The first solid particle module and the first pore fluid module are sequentially included from top to bottom in the depth direction, and the conductive path P s For the second solid particle module, the conductive path P w is a second pore fluid module, and the air path is an air module; Step 2: Configure the same porosity n and different pore fluid conductivity σ w Various mixed soils; Step 3: Measure the conductivity σ of pore fluids with the same porosity n and different pore fluid conductivity σ w The electrical conductivity of the mixed soil corresponding to each mixed soil is σ0, and then the pore fluid conductivity σ w and porosity n, calculate the conductivity σ of the first solid particle module and the second solid particle module s , Among them, σ w is the conductivity of the first pore fluid module and the second pore fluid module, CF is the clay content in the mixed soil, G s1 is the specific gravity of clay in the mixed soil, G s2 is the proportion of sand in the mixed soil. is the mass density of water at 4°C, n is the porosity of the mixed soil, CEC is the cation exchange capacity, Step 4: According to different pore fluid conductivity σ w And the corresponding conductivity σ0, fit the following formula to obtain and L w , According to L u ·L' w +L w =n,L u +L s +L w =1, get L u , L s , L' w , according to L' s +L' w =1, obtain L' s , Among them, L u is the cross-sectional width of the first solid particle module and the first pore fluid module, L w is the cross-sectional width of the second pore fluid module, L' w is the depth of the first pore fluid module, L s is the cross-sectional width of the second solid particle module, L' s is the depth of the first solid particle module; Step 5: Calculate the conductive path P u , P s , P w Contribution to the electrical conductivity of saturated soil, In the formula, CP u is the conductive path P u Contribution to the electrical conductivity of saturated soil, CP s is the conductive path P s Contribution to the electrical conductivity of saturated soil, CP w is the conductive path P w Contribution rate to the electrical conductivity of saturated soil.
2. A method for evaluating the contribution of a conductive path to the electrical conductivity of saturated soil according to claim 1, characterized in that: The process also includes step 6: changing the porosity n, and repeating steps 2-5 to analyze the P under different porosity n conditions. u , P s , P w The contribution rate and changing trend of the conductive path to the electrical conductivity of saturated soil.
3. A method for evaluating the contribution of a conductive path to the electrical conductivity of saturated soil according to claim 1, characterized in that: When the clay content CF in the mixed soil is ≤ 30%, the preparation method of the mixed soil includes the following steps: Put the clay and sand with the set clay content CF into flasks respectively and mix them with the salt solution. Boil to degas the clay slurry and sand slurry in the flasks. After cooling, pour the clay slurry into a cylindrical preparation tube. Wait for the clay slurry to precipitate to the bottom of the preparation tube, then pour the sand slurry. Seal and rotate the preparation tube to mix evenly, and then pour it into the consolidometer to obtain a homogeneous and non-segregated mixed soil through consolidation.
4. A method for evaluating the contribution of a conductive path to the electrical conductivity of saturated soil according to claim 3, characterized in that: When the clay content CF in the mixed soil is ≥ 40% and when the clay content in the mixed soil is 30% < CF < 40%, the preparation method of the mixed soil includes the following steps: Mix the clay and sand according to the clay content CF, then mix evenly with the salt solution according to the predetermined water content, and then pour it into the consolidometer to obtain the mixed soil through consolidation.
5. A method for evaluating the contribution of a conductive path to the electrical conductivity of saturated soil according to claim 4, characterized in that: The salt solution is sodium chloride solution.
6. A method for evaluating the contribution of a conductive path to the electrical conductivity of saturated soil according to claim 4, characterized in that: A conductive sheet for measuring the conductivity σ0 of the mixed soil is arranged in the consolidation cavity of the consolidometer.