A test method for unequal density soil unit body suitable for high and low consolidation stress

Abstract

The application discloses a kind of unequal density soil unit test methods suitable for high-low consolidation stress.The method includes soil sampling and obtaining the basic physical parameters such as porosity ratio and specific gravity of soil sample, whether the soil sample meets the requirement of triaxial consolidation test according to the basic physical parameters, if it meets, triaxial consolidation test under different consolidation pressure is carried out, critical state porosity ratio-average effective stress curve is obtained and fitting parameter is determined;According to the given stress ratio and fitting parameter, prepare soil unit sample, carry out triaxial consolidation test on soil unit sample, obtain the initial physical parameters of soil unit sample;The initial physical parameters are corrected using stress ratio, and the final mechanical property results of soil unit sample are obtained.The application can expand the test capacity of existing unit test instrument, reduce the difficulty of unit test under high-low consolidation pressure condition, and accurately determine the mechanical properties of unequal density soil unit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geotechnical engineering unit test theory, and particularly relates to a unit test method for soil with different densities under high and low consolidation stresses. BACKGROUND

[0002] A large number of earth-rock dam projects planned and constructed in the southwest region of China are often built in high-intensity seismic areas, and the dam foundation often has a hundred-meter-thick deep overburden layer. Under the action of strong earthquakes, the overburden layer is prone to liquefaction, and a large pore water pressure is generated, which reduces the stiffness of the dam foundation and causes excessive deformation, which has a significant impact on the stability and normal operation of the earth-rock dam. In order to obtain the response law of the dam and the dam foundation under the action of earthquakes and evaluate the liquefaction risk, it is necessary to carry out unit tests.

[0003] The overburden layer refers to various loose accumulations and sediments deposited on the bedrock. In engineering, it is generally considered that the overburden layer with a depth greater than 30m is a deep overburden layer. Soil liquefaction refers to the decrease in effective stress due to the rise in pore water pressure of saturated soil under the action of earthquakes or other dynamic loads, resulting in the loss of shear strength and carrying capacity of the soil. Unit test refers to a test for studying the properties of soil at the scale of soil unit, such as stress-strain relationship, stiffness characteristics, etc. Through research, it is found that the upper limit of the test capacity of most dynamic triaxial apparatuses, hollow cylinder torsional shear apparatuses or cyclic simple shear apparatuses is about 1MPa, and only a small number of tests are carried out under the working condition of 1-2MPa, which is far from the overburden pressure of 4-5MPa of the foundation after dam construction. It is almost impossible to test using existing instruments.

[0004] The critical state refers to the state of soil in the process of shear test, when the strain of the soil gradually develops to a large deformation level, at a certain moment, the shear strain continues to develop, but the volume strain and deviatoric stress no longer develop but tend to be flat. At this time, it can be considered that the soil has entered the critical state. The difference between the void ratio of the soil under a certain consolidation pressure and the critical state void ratio of the soil after entering the critical state controls the strength and deformation parameters of the soil to some extent. Therefore, in the unit test, controlling the same difference in the void ratio can ensure that the physical and mechanical responses between the two samples are similar.

[0005] However, in the existing technology, when carrying out unit tests of dam body or dam foundation soil materials, it is often difficult to produce low-density samples with high accuracy or the instrument range cannot reach the required high consolidation pressure of 4-5MPa. In the case that existing instruments and test technologies generally do not meet the actual requirements, it is necessary to develop a new unit test method to obtain the mechanical properties of low-density samples or high-consolidation-pressure soil using the performance of existing instruments, and to provide a theoretical basis for the seismic safety evaluation of high earth-rock dams represented by the earth-rock dam projects in the southwest region. SUMMARY

[0006] To address the problems existing in the unit cell testing techniques for geotechnical engineering under different densities and consolidation pressures in the background art, this invention discloses a unit cell testing method for unequal-density soils with high and low consolidation stresses. By controlling the difference Δe between the consolidation void ratio and the critical void ratio to be the same in both the target and the test, the stress-strain relationship of soil units with different densities under different consolidation pressures is made similar. This expands the testing capabilities of existing unit cell testing instruments and reduces the difficulty of unit cell testing under high and low consolidation pressure conditions.

[0007] The technical solution adopted in this invention is as follows, specifically including the following steps:

[0008] Step S1: First, soil samples are taken from the site to obtain soil samples. The consolidation pressure (σ′) of the soil sample is determined based on the sampling depth. tar Soil mechanics tests were conducted on soil samples indoors to obtain the basic physical parameters of the soil samples; these basic physical parameters included void ratio and specific gravity G. s and relative density;

[0009] Step S2: Determine whether the soil sample meets the initial triaxial consolidation test requirements based on the basic physical parameters obtained in Step S1. If it does, proceed to Step S3; otherwise, return to Step S1 and select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements.

[0010] Step S3: Conduct initial triaxial consolidation tests under different consolidation pressures to obtain the critical state void ratio e of soil samples under different consolidation pressures. c and average effective stress p c The fitting parameters were determined by fitting the critical state porosity-average effective stress curve.

[0011] Step S4: Design the stress ratio N corresponding to the triaxial consolidation test target. σ According to the stress ratio N σ The target dry density ρ of the soil element sample was determined by fitting parameters. dt and with the target dry density ρ dt The soil unit sample was prepared by using the actual dry density of the soil unit sample.

[0012] Step S5: Conduct a target triaxial consolidation test on the soil unit sample to obtain the initial physical parameters of the soil unit sample during the target triaxial consolidation test; the initial physical parameters include physical parameters to be corrected and physical parameters not to be corrected.

[0013] Step S6: Correct the physical parameters to be corrected for the soil unit sample to obtain the target physical parameters, and use the target physical parameters of the soil unit sample as the final mechanical property results of the soil unit sample.

[0014] The specific method for obtaining the basic physical parameters of the soil sample in step S1 is as follows:

[0015] First, soil mechanics tests were conducted on the soil samples indoors to obtain the maximum void ratio e of the soil samples. max Minimum porosity e min Specific gravity G s According to the porosity (e0) after consolidation. tar ;

[0016] Next, the dry density ρ of the soil sample is obtained according to the following formula. d and relative density D r :

[0017]

[0018] Among them, (e0) tar D represents the void ratio of the soil sample after consolidation. r e represents the relative density of the soil sample after consolidation. max e represents the maximum void ratio of the soil sample. min G represents the minimum void ratio of the soil sample. s This represents the specific gravity of the soil sample.

[0019] The specific steps of S2 are as follows:

[0020] Based on the relative density D of the soil sample r and consolidation pressure (σ′) tar Determine whether the soil sample meets the initial requirements for triaxial consolidation testing:

[0021] If the relative density D of the soil sample r <40%, or the consolidation pressure (σ′) of the soil sample. tar Greater than the given consolidation stress threshold σ max If the soil sample meets the initial triaxial consolidation test requirements, proceed to step S3.

[0022] Otherwise, it indicates that the soil sample does not meet the initial triaxial consolidation test requirements, and the process returns to step S1 to select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements.

[0023] The specific steps of step S3 are as follows:

[0024] Step S3.1: Conduct a triaxial consolidation test on the soil sample. During the test, monitor the volumetric strain, strain, and deviatoric stress of the soil sample in real time. Simultaneously generate the "volume strain-strain" and "deviatoric stress-strain" curves of the soil sample. When both the "volume strain-strain" and "deviatoric stress-strain" curves are horizontal, it indicates that the soil sample has entered the critical state. Record the average effective stress p of the soil sample at the critical state. c ′, and based on the volume change under critical conditions, the critical state porosity e of the soil sample is obtained. c Critical porosity e c Specifically, it is obtained by processing according to the following formula:

[0025] e c =(e0) tar +ε v (1+(e0) tar )

[0026]

[0027] Among them, (e0) tar ε represents the void ratio of the soil sample after consolidation. v V represents the volumetric strain of a soil sample when it reaches a critical state. w ′ represents the volume of water drained or infiltrated into the soil sample during the triaxial consolidation test, and V represents the total volume of the soil sample.

[0028] Step S3.2: Change the consolidation pressure during the triaxial consolidation test and repeat step S3.1 multiple times to obtain the average effective stress p of the soil sample under different consolidation pressures. c ′ and critical state porosity e c The average effective stress p is obtained according to the following formula. c ′ and critical state porosity e c Perform a fitting operation to obtain the fitting parameters:

[0029]

[0030] Where a, b, and c are all fitting parameters.

[0031] The specific steps of S4 are as follows:

[0032] Step S4.1: First, design a stress ratio N corresponding to a target triaxial consolidation test. σ Stress ratio N σ The following formula is used to obtain it:

[0033]

[0034] Where, (σ′) tar Let σ′ be the consolidation pressure of the soil sample.test The consolidation pressure for the pre-set target triaxial consolidation test;

[0035] Step S4.2, based on the stress ratio N σ The target void ratio (e0) of the soil unit sample is obtained according to the following formula. test and target dry density ρ dt :

[0036]

[0037] (p c ′) tar =(σ′) tar

[0038] In the formula, b and c are both fitting parameters, (e0) tar The void ratio of the soil sample after consolidation (p) c ′) tar This represents the average effective stress of the soil sample after consolidation.

[0039] Step S4.3: Finally, the target dry density ρ dt The soil unit sample was prepared using the actual dry density of the soil unit sample to be tested.

[0040] The specific method of step S6 is as follows:

[0041] Multiply the physical parameters to be corrected of the soil unit sample by the stress ratio N. σ The product obtained by multiplication is used as the target physical parameter of the soil unit sample, and the corrected target physical parameter of the soil unit sample is used as the final mechanical property result of the soil unit sample.

[0042] The physical parameters to be corrected include average effective stress, shear stress, peak strength, instability strength, and excess pore water pressure, while the physical parameters not to be corrected include strain, peak friction angle, and liquefaction resistance.

[0043] The beneficial effects of the method of the present invention are as follows:

[0044] 1. In unit cell testing, by controlling the difference between the consolidated void ratio and the critical void ratio of the sample to be the same, the stress-strain relationship of soil units with different densities under different consolidation pressures is made similar. This can expand the testing capabilities of existing unit cell testing instruments, obtain approximate test results beyond the instrument's capabilities, and reduce the difficulty of unit cell testing under high consolidation pressure conditions.

[0045] 2. When the required density is too low to prepare samples and conduct successful tests, a conversion method is provided to transform the low-stress, low-density sample into a sample with stress and density within a reasonable test range and conduct the test, thereby reducing the difficulty of unit cell testing under low consolidation pressure and low density conditions.

[0046] 3. This invention can qualitatively analyze the relative accuracy of test results by comparing the similarity of unit cell tests under different consolidation pressures under specific conditions. Attached Figure Description

[0047] Figure 1 This is a flowchart of the method of the present invention;

[0048] Figure 2 This is a schematic diagram of the Critical State Line (CSL) of the soil in the embodiment.

[0049] Figure 3 This is a schematic diagram of the stress-strain relationship transformation of specimen A in the example. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0051] The method of the present invention includes the following steps:

[0052] Step S1: First, soil samples are taken from the sandy site to obtain soil samples. The consolidation pressure (σ′) of the soil sample is determined based on the sampling depth. tar Soil mechanics tests were conducted on soil samples indoors to obtain the basic physical parameters of the soil samples; these basic physical parameters included void ratio and specific gravity G. s and relative density;

[0053] Step S2: Determine whether the soil sample meets the initial triaxial consolidation test requirements based on the basic physical parameters obtained in Step S1. If it does, proceed to Step S3; otherwise, return to Step S1 and select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements.

[0054] Step S3: Conduct initial drained or undrained triaxial consolidation tests under different consolidation pressures to obtain the critical state void ratio e of soil samples under different consolidation pressures. c and average effective stress p c The fitting parameters were determined by fitting the critical state porosity-average effective stress curve.

[0055] Step S4: Design the stress ratio N corresponding to the triaxial consolidation test target. σ According to the stress ratio N σ The target dry density ρ of the soil element sample was determined by fitting parameters. dt Parameters, and with the target dry density ρ dt The soil unit sample was prepared by using the actual dry density of the soil unit sample.

[0056] In practice, if the relative density D of the soil sample r If <40%, then (e0) test Less than (e0) tar Stress ratio N σ <1, the void ratio of the soil unit sample relative to the soil mass sample decreases, the consolidation pressure increases, and the difficulty of model preparation decreases; if the consolidation pressure (σ′) of the soil mass sample... tar Greater than the given consolidation stress threshold (p) c ′) max Then (e) test Greater than (e) tar Stress ratio N σ >1. Consolidation stress is reduced to the stress that the experimental instrument can provide. Under normal circumstances, soil samples will not simultaneously meet both of these requirements. Under relatively high consolidation pressure, the soil will be consolidated to a density not required for the test; otherwise, an unstable state will generally not exist.

[0057] Step S5, under consolidation pressure (σ′) test Under the following conditions, a target triaxial consolidation test is carried out on the soil unit sample to obtain the initial physical parameters of the soil unit sample during the target triaxial consolidation test; the initial physical parameters include physical parameters to be corrected and physical parameters not to be corrected.

[0058] Step S6: Correct the physical parameters to be corrected for the soil unit sample to obtain the target physical parameters, and use the target physical parameters of the soil unit sample as the final mechanical property results of the soil unit sample.

[0059] The specific method for obtaining the basic physical parameters of the soil sample in step S1 is as follows:

[0060] First, soil mechanics tests were conducted on the soil samples indoors to obtain the maximum void ratio e of the soil samples. max Minimum porosity e min Specific gravity G s According to the porosity (e0) after consolidation. tar ;

[0061] Next, the dry density ρ of the soil sample is obtained according to the following formula. d and relative density D rFor use in subsequent triaxial consolidation tests:

[0062]

[0063] Among them, (e0) tar D represents the void ratio of the soil sample after consolidation. r e represents the relative density of the soil sample after consolidation. max e represents the maximum void ratio of the soil sample. min G represents the minimum void ratio of the soil sample. s This represents the specific gravity of the soil sample.

[0064] The specific method for step S2 is as follows:

[0065] Based on the relative density D of the soil sample r and consolidation pressure (σ′) tar Determine whether the soil sample meets the initial requirements for triaxial consolidation testing:

[0066] If the relative density D of the soil sample r <40%, or the consolidation pressure (σ′) of the soil sample. tar Greater than the given consolidation stress threshold (p) c ′) max If the soil sample meets the initial triaxial consolidation test requirements, proceed to step S3.

[0067] Otherwise, it indicates that the soil sample does not meet the initial triaxial consolidation test requirements, and the process returns to step S1 to select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements.

[0068] Among them, the consolidation stress threshold (p c ′) max The maximum consolidation stress value that the test instrument can achieve during the initial triaxial consolidation test is used.

[0069] In specific implementation, step S3 is as follows:

[0070] Step S3.1: Conduct a triaxial consolidation test on the soil sample. During the test, monitor the volumetric strain, strain, and deviatoric stress of the soil sample in real time. Simultaneously generate the "volume strain-strain" and "deviatoric stress-strain" curves of the soil sample. When both the "volume strain-strain" and "deviatoric stress-strain" curves gradually flatten or become horizontal, it indicates that the soil sample has entered the critical state. Record the average effective stress p of the soil sample at the critical state. c ′, and based on the volume change under critical conditions, the critical state porosity e of the soil sample is obtained. c Critical porosity e c Specifically, it is obtained by processing according to the following formula:

[0071] e c =(e0) tar +ε v (1+(e0) tar )

[0072]

[0073] Among them, (e0) tar The void ratio of the soil sample after consolidation is obtained from step S1, ε. v V represents the volumetric strain of a soil sample when it reaches a critical state. w ′ represents the volume of water drained or infiltrated into the soil sample during the triaxial consolidation test, and V represents the total volume of the soil sample.

[0074] Step S3.2: Change the consolidation pressure during the triaxial consolidation test and repeat step S3.1 multiple times to obtain the average effective stress p of the soil sample under different consolidation pressures. c ′ and critical state porosity e c The average effective stress p is obtained according to the following formula. c ′ and critical state porosity e c Perform a fitting operation to obtain the fitting parameters:

[0075]

[0076] Where a, b, and c are all fitting parameters.

[0077] The specific steps of step S4 are as follows:

[0078] Step S4.1: First, design a stress ratio N corresponding to a target triaxial consolidation test. σ Stress ratio N σ The following formula is used to obtain it:

[0079]

[0080] Where, (σ′) tar Let (σ′) be the consolidation pressure of the soil sample determined based on depth. test The consolidation pressure for the pre-set target triaxial consolidation test;

[0081] Step S4.2, based on the stress ratio N σ The target void ratio (e0) of the soil unit sample is obtained according to the following formula. test and target dry density ρ dt :

[0082]

[0083] (p c ′)tar =(σ′) tar

[0084] In the formula, b and c are both fitting parameters, (e0) tar The void ratio of the soil sample after consolidation (p) c ′) tar This represents the average effective stress of the soil sample after consolidation.

[0085] Step S4.3: Finally, the target dry density ρ dt The soil unit sample was prepared using the actual dry density of the soil unit sample to be tested.

[0086] The specific method of step S6 is as follows:

[0087] Multiply the physical parameters to be corrected of the soil unit sample by the stress ratio N. σ The product obtained by multiplication is used as the target physical parameter of the soil unit sample, and the corrected target physical parameter of the soil unit sample is used as the final mechanical property result of the soil unit sample.

[0088] The physical parameters to be corrected include average effective stress, shear stress, peak strength, instability strength, and excess pore water pressure, while the physical parameters not to be corrected include strain, peak friction angle, and liquefaction resistance. These physical parameters do not require any correction and can be kept at their original values.

[0089] In this embodiment, the prototype is simplified to a 100m deep horizontal overburden sandy soil site. Two sets of consolidated drained triaxial tests are to be conducted on the soil at depths of 2m and 80m, referred to as soil samples A and B, respectively. The maximum consolidation stress (p) that the triaxial tests used can provide is... c ′) max =600 kPa. The set void ratio (e0) of the two groups of soil samples after consolidation. tar The consolidation pressures (σ′) are 0.715 and 0.560, respectively. tar The values ​​are 20 kPa and 800 kPa.

[0090] The overall implementation process is as follows: Figure 1 As shown.

[0091] The first step is to conduct soil mechanics tests according to the "Industry Standard of the People's Republic of China: Geotechnical Testing Procedures (SL237-1999)" to determine the maximum void ratio e of the soil sample. max =0.870, minimum void ratio e min =0.472, the specific gravity G of the soil sample s =2.644; The relative density D of the two groups of soil samples was obtained using the formula. r The figures are 38.9% and 77.9%;

[0092] The second step is to check whether soil samples A and B meet the requirements of the initial triaxial consolidation test in step 2. Soil sample A meets the relative density D. r <40%, the consolidation pressure of soil sample B is 800 kPa, which is greater than the given consolidation stress threshold σ. max =500kPa;

[0093] The third step is to conduct initial triaxial consolidation drainage tests, designed to be performed under different consolidation pressures:

[0094] Static compression tests can be conducted in this embodiment at effective consolidation pressures of 25 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, and 600 kPa. The critical state porosity e under different consolidation pressures is determined. c and average effective stress p c The critical state line (CSL) of the soil sample was fitted. In this embodiment, the values ​​of a, b, and c for soil sample A are approximately 0.783, -0.035, and 0.776, respectively; the resulting CSL curve of the test soil is shown below. Figure 2 As shown.

[0095] The fourth step is to design the consolidation pressure (σ′) of the soil element specimen in the triaxial consolidation test. test =100kPa, the stress ratio N of soil sample A is obtained. σ =0.2; Consolidation pressure (σ′) of soil sample B. test =200kPa, stress ratio N σ =4, and then calculate the target void ratio (e0) of the soil unit samples corresponding to soil samples A and B respectively. test The values ​​are 0.690 and 0.676, respectively, for the target dry density ρ. dt It is 1.564 g / cm³ 3 and 1.578 g / cm 3 ; with target dry density ρ dt As the actual dry density of the soil unit sample, the soil unit sample was prepared in accordance with the "Industry Standard of the People's Republic of China: Geotechnical Testing Procedure (SL237-1999)".

[0096] The fifth step involves conducting a target triaxial consolidation test on the soil unit specimen to obtain its initial physical parameters. Taking the stress-strain relationship of soil unit specimen A corresponding to soil sample A as an example, the conversion of the test results into target unit test results is explained. Figure 3 As shown, the solid line represents the soil element sample A at a void ratio (e0). test =0.69, consolidation pressure (σ′) testThe stress-strain curve obtained from a triaxial consolidated drained test under a pressure of 100 kPa. To obtain the target physical parameter value, i.e. (e0) tar =0.715, consolidation pressure (σ′) tar The stress-strain relationship at 20 kPa, according to the transformation relationship in Table 1, requires keeping the strain constant and multiplying the deviatoric stress coefficient by the stress ratio N. σ =0.2 is sufficient.

[0097] Table 1. Criteria for converting the results of the target triaxial consolidation test.

[0098]

[0099] The final target stress-strain relationship is as follows: Figure 3 As shown by the dashed line. Based on Table 1 and the stress ratio N... σ The initial physical parameters of the soil unit sample can be transformed into target physical parameters, and the corresponding effect can be seen. The target physical parameters are the final mechanical properties of the soil unit sample.

Claims

1. A test method for unequal-density soil elements suitable for high and low consolidation stresses, characterized in that, Includes the following steps: Step S1: First, soil samples are taken from the site to obtain soil samples. The consolidation pressure (σ′) of the soil sample is determined based on the sampling depth. tar Soil mechanics tests were conducted on soil samples indoors to obtain the basic physical parameters of the soil samples; these basic physical parameters included void ratio and specific gravity G. s and relative density; Step S2: Determine whether the soil sample meets the initial triaxial consolidation test requirements based on the basic physical parameters obtained in Step S1. If it does, proceed to Step S3; otherwise, return to Step S1 and select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements. Step S3: Conduct initial triaxial consolidation tests under different consolidation pressures to obtain the critical state void ratio e of soil samples under different consolidation pressures. c and average effective stress p c The fitting parameters were determined by fitting the critical state porosity-average effective stress curve. Step S4: Design the stress ratio N corresponding to the triaxial consolidation test target. σ According to the stress ratio N σ The target dry density ρ of the soil element sample was determined by fitting parameters. dt and with the target dry density ρ dt The soil unit sample was prepared by using the actual dry density of the soil unit sample. Step S4.1: First, design a stress ratio N corresponding to a target triaxial consolidation test. σ Stress ratio N σ The following formula is used to obtain it: Where, (σ′) tar Let σ′ be the consolidation pressure of the soil sample. test The consolidation pressure for the pre-set target triaxial consolidation test; Step S4.2, based on the stress ratio N σ The target void ratio (e0) of the soil unit sample is obtained according to the following formula. test and target dry density ρ dt : (p c ′)tar=(σ′)tar In the formula, b and c are both fitting parameters, (e0) tar The void ratio of the soil sample after consolidation (p) c ′) tar This represents the average effective stress of the soil sample after consolidation. Step S4.3: Finally, the target dry density ρ dt The soil unit sample was prepared by using the actual dry density of the soil unit sample to be tested. Step S5: Conduct a target triaxial consolidation test on the soil unit sample to obtain the initial physical parameters of the soil unit sample during the target triaxial consolidation test; the initial physical parameters include physical parameters to be corrected and physical parameters not to be corrected. Step S6: Correct the physical parameters to be corrected for the soil unit sample to obtain the target physical parameters, and use the target physical parameters of the soil unit sample as the final mechanical property results of the soil unit sample.

2. The test method for unequal-density soil elements with high and low consolidation stress according to claim 1, characterized in that: The specific method for obtaining the basic physical parameters of the soil sample in step S1 is as follows: First, soil mechanics tests were conducted on the soil samples indoors to obtain the maximum void ratio e of the soil samples. max Minimum porosity e min Specific gravity G s According to the porosity (e0) after consolidation. tar ; Next, the dry density ρ of the soil sample is obtained according to the following formula. d and relative density D r : Among them, (e0) tar D represents the void ratio of the soil sample after consolidation. r e represents the relative density of the soil sample after consolidation. max e represents the maximum void ratio of the soil sample. min G represents the minimum void ratio of the soil sample. s This represents the specific gravity of the soil sample.

3. The test method for unequal-density soil elements with high and low consolidation stress according to claim 1, characterized in that: The specific steps of S2 are as follows: Based on the relative density D of the soil sample r and consolidation pressure (σ′) tar Determine whether the soil sample meets the initial requirements for triaxial consolidation testing: If the relative density D of the soil sample r <40%, or the consolidation pressure (σ′) of the soil sample. tar Greater than the given consolidation stress threshold σ max If the soil sample meets the initial triaxial consolidation test requirements, proceed to step S3. Otherwise, it indicates that the soil sample does not meet the initial triaxial consolidation test requirements, and the process returns to step S1 to select a new soil sample until the soil sample meets the initial triaxial consolidation test requirements.

4. The test method for unequal-density soil elements with high and low consolidation stress according to claim 1, characterized in that: The specific steps of step S3 are as follows: Step S3.1: Conduct a triaxial consolidation test on the soil sample. During the test, monitor the volumetric strain, strain, and deviatoric stress of the soil sample in real time. Simultaneously generate the "volume strain-strain" and "deviatoric stress-strain" curves of the soil sample. When both the "volume strain-strain" and "deviatoric stress-strain" curves are horizontal, it indicates that the soil sample has entered the critical state. Record the average effective stress p of the soil sample at the critical state. c ′, and based on the volume change under critical conditions, the critical state porosity e of the soil sample is obtained. c Critical porosity e c Specifically, it is obtained by processing according to the following formula: by c (e0) tar +ε v (1+(e0) tar ) Among them, (e0) tar ε represents the void ratio of the soil sample after consolidation. v V represents the volumetric strain of a soil sample when it reaches a critical state. w ′ represents the volume of water drained or infiltrated into the soil sample during the triaxial consolidation test, and V represents the total volume of the soil sample. Step S3.2: Change the consolidation pressure during the triaxial consolidation test and repeat step S3.1 multiple times to obtain the average effective stress p of the soil sample under different consolidation pressures. c ′ and critical state porosity e c The average effective stress p is obtained according to the following formula. c ′ and critical state porosity e c Perform a fitting operation to obtain the fitting parameters: Where a, b, and c are all fitting parameters.

5. The test method for unequal-density soil elements with high and low consolidation stress according to claim 1, characterized in that: The specific method of step S6 is as follows: Multiply the physical parameters to be corrected of the soil unit sample by the stress ratio N. σ The product obtained by multiplication is used as the target physical parameter of the soil unit sample, and the corrected target physical parameter of the soil unit sample is used as the final mechanical property result of the soil unit sample.

6. The test method for unequal-density soil elements with high and low consolidation stress according to claim 1, characterized in that: The physical parameters to be corrected include average effective stress, shear stress, peak strength, instability strength, and excess pore water pressure, while the physical parameters not to be corrected include strain, peak friction angle, and liquefaction resistance.

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