Quantitative methods for differentiating collapsible soils under different pressures and for determining collapsibility.

Abstract

This invention discloses a method for quantitatively distinguishing between collapsibility and solution collapse in wet-dissolvable soils under different pressures, comprising the following steps: 1. Sampling and preparing undisturbed soil samples using a ring cutter; 2. Immersion and saturated consolidation tests with different solutions; 3. Correcting the settlement stability height under various pressures in the consolidation tests with saturated distilled water and saturated NaCl solution; 4. Calculating the additional settlement per unit thickness of the undisturbed soil sample under various pressures; 5. Quantitatively calculating the solution collapse per unit thickness of the undisturbed soil sample under various pressures using the difference method; 6. Determining the dominance of collapsibility and solution collapse under various pressures. This invention is highly operable and has a short testing cycle. By using different solutions to test undisturbed soil samples, it separates collapsibility and quantitatively distinguishes between collapsibility and solution collapse. By setting intervals for the collapsibility coefficient, solution collapse coefficient, and total settlement coefficient, it qualitatively determines the dominance of collapsibility and solution collapse, effectively solving the problem of quantitatively distinguishing between collapsibility and solution collapse in wet-dissolvable soils in geotechnical engineering.

Description

Technical Field

[0001] This invention belongs to the field of soil layer characteristic research technology, specifically relating to a method for quantitatively distinguishing between wet collapse and solution collapse of soil under different pressures. Background Technology

[0002] Currently, the methods used in building technical specifications for saline soil areas at home and abroad to obtain the collapse coefficient are basically the same as those used in collapsibility tests. However, it is impossible to qualitatively and quantitatively determine whether the collapse of saline soil contains collapsibility. In recent years, most domestic and foreign studies have focused on independent research on collapsibility and solution using salt washing and remolding test samples. However, these studies suffer from problems such as long test cycles, large errors in test results, and the inability to provide objective evaluation. Qualitatively and quantitatively distinguishing between collapsibility and solution in collapsible soil has become a difficult problem in the geotechnical engineering field.

[0003] Therefore, there is an urgent need for a method that is simple in procedure, short in cycle, and reasonably designed to qualitatively and quantitatively distinguish between collapsibility and solution collapse under different pressures in wet collapsible soils, and to solve the problem that existing technologies cannot directly use undisturbed soil samples to qualitatively and quantitatively determine collapsibility and solution collapse under different pressures in wet collapsible soils. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for quantitatively distinguishing between wet collapse and solution collapse in collapsible soil under different pressures. The method is simple, using distilled water and saturated NaCl solution to conduct immersion and saturated consolidation tests under different pressures to separate the wet collapse. Simultaneously, the saturated settlement stability height under different pressures in the saturated consolidation test is corrected to the immersion stability height, thus quantitatively distinguishing between wet collapse and solution collapse under different pressures. Based on this quantitative distinction, by setting intervals for the wet collapse coefficient, solution collapse coefficient, and total settlement coefficient, the dominance of wet collapse and solution collapse under each pressure can be qualitatively determined. Furthermore, the method proposes a method for determining whether to use the total settlement calculation as the amount of solution collapse or wet collapse, effectively solving the problem of quantitatively distinguishing between wet collapse and solution collapse in collapsible soil in geotechnical engineering.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for quantitatively distinguishing between wet collapsible soil and the determination of collapse under different pressures, characterized in that the method includes the following steps: Step 1: Sampling and Preparation of Uncircular Soil Samples: Take one undisturbed soil sample from the soil layer to be evaluated and prepare four samples at heights of [missing information]. The undisturbed soil samples from the ring cutter are the first ring cutter undisturbed soil sample, the second ring cutter undisturbed soil sample, the third ring cutter undisturbed soil sample, and the fourth ring cutter undisturbed soil sample. Step 2: Immersion and Consolidation Tests with Different Solutions: Using distilled water as the solution, an immersion and consolidation test was conducted on the undisturbed soil sample of the first ring cutter under the rated pressure P. The stable settling height of the undisturbed soil sample of the first ring cutter under the rated pressure P was obtained. Simultaneously, saturated distilled water consolidation tests were conducted on the undisturbed soil samples of the second ring cutter under pressure levels 1 to n, obtaining the stable saturated water settlement height of the undisturbed soil samples of the second ring cutter under pressure levels 1 to n. , … Where n is a positive integer and n>2, the nth pressure level is equal to the rated pressure P; Using saturated NaCl solution as the solution, a consolidation test was conducted on the undisturbed soil sample of the third ring cutter under the rated pressure P by immersion in saturated NaCl solution. The stable settling height of the undisturbed soil sample of the third ring cutter under the rated pressure P was obtained. Simultaneously, saturated NaCl solution consolidation tests were conducted on the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n, obtaining the saturated settlement stability height of the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n. , … ; Step 3: Correcting the settling stability height under various pressures in the consolidation tests of saturated distilled water and saturated NaCl solution: Using the settling stability height under immersion as a benchmark, respectively, through correction factors... and The saturated water settling stability heights under various pressures within the rated pressure range of saturated distilled water and saturated NaCl solution were corrected to obtain the immersion settling stability heights under pressures of levels 1 to n with distilled water as the solution. , … And the stable immersion sinking height under the first to nth pressures using saturated NaCl solution as the solution. , … ; Step 4: Calculate the additional settlement per unit thickness of the undisturbed soil sample under various pressures. The process is as follows: According to the formula The calculations yielded the results for the first and second ring cutter undisturbed soil samples using distilled water as the solution at the [missing information]. Additional subsidence per unit thickness under pressure ,in, are positive integers and ≤n, For the undisturbed soil sample from the ring cutter, at the first The stable sinking height of the unsubmerged unit under pressure; According to the formula Calculations were performed on the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution in the [missing information]. Additional subsidence per unit thickness under pressure ; Step 5: Quantitatively calculate the solution collapse per unit thickness of the undisturbed soil sample under various pressures using the difference method: According to the formula... The calculations yielded the undisturbed soil sample at the [number]th [year]. Dissolution volume per unit thickness under high pressure ; Step 6: Determining the dominance of wet collapse and solution collapse under various pressures, the process is as follows: when <0.01 and If the pressure is ≥0.015, the soil layer is determined to be collapsible saline soil under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; when <0.005, 0.01≤ <0.015 and When the pressure is ≥0.015, the soil layer is determined to be saline soil that can be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; When 0.005≤ <0.01, <0.01 and 0.01≤ If the value is less than 0.015, the soil layer is determined to be saline soil that can be considered as collapsible under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; when ≥0.01 and If the pressure is less than 0.015, the soil layer is determined to be saline soil with collapsibility under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; When 0.005≤ <0.01, 0.005< <0.015, and 0.015≤ When <0.025, the soil layer is determined to be saline soil that can be considered as collapsible and soluble under this pressure; when ≥0.01、 When the pressure is ≥0.015, the soil layer is determined to be saline soil with collapsibility and solubility under that pressure. when <0.01, <0.01, and If the pressure is less than 0.01, the soil layer is determined to be saline soil that does not exhibit collapsibility or solubility under that pressure, and is classified as ordinary saline soil. It is used as a deformation coefficient to calculate the deformation of the soil layer it represents.

[0006] The above-mentioned method for quantitatively distinguishing between wet collapsible soil and its collapsibility determination under different pressures is characterized in that: in step two, before conducting the immersion consolidation test on the first ring cutter undisturbed soil sample under the rated pressure P, the first ring cutter undisturbed soil sample is pressurized step by step until the rated pressure is reached, thereby obtaining the settlement stability height of the ring cutter undisturbed soil sample under the first to nth pressure levels without immersion. , … .

[0007] The above-mentioned quantitative method for distinguishing between collapsible and wet-dissolution soils under different pressures is characterized in that: in step three, according to the formula... The correction factor for correcting the results of the consolidation test of the second ring cutter undisturbed soil sample with saturated distilled water was calculated. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the immersion in distilled water and consolidation tests with saturated distilled water. The second ring cutter undisturbed soil sample should be tested on the [date missing]. Corrected immersion sinking stability height under pressure ; According to the formula The correction factor was calculated to correct the results of the consolidation test of the undisturbed soil sample in saturated NaCl solution for the fourth ring cutter. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the consolidation tests with saturated NaCl solution and saturated NaCl solution. The fourth ring cutter undisturbed soil sample was tested on the [missing information - likely a date or time]. Corrected immersion sinking stability height under pressure .

[0008] The above-mentioned quantitative method for distinguishing between collapsible and solution-prone soils under different pressures is characterized in that: in step six, when the undisturbed soil sample is saline soil that can be considered as collapsible and solution-prone under that pressure, the saline soil that can be considered as collapsible and solution-prone under that pressure is classified into saline soil that can be considered as collapsible and saline soil that can be considered as solution-prone according to the degree of dominance of collapsibility and solution-proneness in settlement deformation, that is, when 1.5 ≤ At that time, the soil layer was determined to be saline soil that could be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the representative soil layer; when 1.5 > At that time, the soil layer was determined to be saline soil that could be considered as collapsible under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

[0009] The above-mentioned method for quantitatively distinguishing between collapsible and solution-prone soils under different pressures is characterized in that: in step six, when the undisturbed soil sample is saline soil exhibiting both collapsibility and solution-proneness under that pressure, the saline soil is classified into collapsibility-dominated saline soil and solution-dominated saline soil based on the degree of dominance of collapsibility and solution-proneness in settlement deformation, i.e., when 1.5... ≤ At that time, the soil layer was determined to be saline soil dominated by collapsibility under that pressure. The collapse amount is calculated using the collapse coefficient; when 1.5 > At that time, the soil layer was determined to be saline soil dominated by dissolution under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

[0010] 1. The method of the present invention has simple steps, does not require salt washing, is highly operable, has a short experimental cycle, and is novel in design and easy to promote and use.

[0011] 2. This invention uses undisturbed soil samples for testing, and the test is completed without disturbing the undisturbed soil samples. The data obtained is more objective and consistent with reality, and solves the error caused by the damage to the original structure in the remodeling test.

[0012] 3. This invention uses saturated NaCl solution to conduct immersion and saturated consolidation tests, successfully inhibiting the dissolution of crystalline salts and salt solutions in saline soil during the test. It directly and completely separates the subsidence without disturbing the original structure of the saline soil, resulting in more objective and realistic data, and solving a problem that has restricted the geotechnical engineering community.

[0013] 4. This invention corrects the saturated water settlement stability height under different pressures in the consolidation test of saturated distilled water and saturated NaCl solution to the immersion stability height, quantitatively distinguishes between wet collapse and solution collapse under different pressures, and provides calculation formulas for the total settlement coefficient, wet collapse coefficient and solution collapse coefficient under each pressure after separation. This facilitates the quantitative acquisition of wet collapse and solution collapse under different pressures, and makes it easier to achieve an objective evaluation of soil layers.

[0014] 5. Based on the quantitative differentiation of collapsibility and solution collapse under various pressures, this invention can qualitatively determine the dominance of collapsibility and solution collapse under various pressures by setting the range of collapsibility coefficient, solution collapse coefficient and total settlement coefficient. It also proposes a method to determine whether to use total settlement as the amount of solution collapse or collapsibility collapse when calculating. This can effectively solve the problem of quantitatively differentiating between collapsibility and solution collapse in collapsible soils in geotechnical engineering, and thus effectively avoid engineering quality problems, engineering cost problems and operation-period problems in saline soil areas.

[0015] In summary, the method of this invention is simple in its steps. It separates collapsibility by using distilled water and saturated NaCl solution to conduct immersion and saturated consolidation tests under different pressures. At the same time, it corrects the saturated settlement stability height under different pressures in the saturated consolidation test to the immersion stability height, quantitatively distinguishing between collapsibility and solution collapse under different pressures. Based on the quantitative distinction between collapsibility and solution collapse under each pressure, it can qualitatively determine the dominance of collapsibility and solution collapse under each pressure by setting the range of collapsibility coefficient, solution collapse coefficient and total settlement coefficient. It also proposes a method to determine whether to use total settlement as the amount of solution collapse or collapsibility collapse when calculating, which can effectively solve the problem of quantitatively distinguishing between collapsibility and solution collapse in collapsible soils in geotechnical engineering.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention.

[0018] Figure 2 This is a schematic diagram of the installation structure of the undisturbed soil sample using the ring cutter of the present invention.

[0019] Figure 3 This is a graph showing the relationship between the height of the first and second ring cutter undisturbed soil samples and the loading pressure, using distilled water as the solution in this invention.

[0020] Figure 4 This is a graph showing the relationship between the height and loading pressure of the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution as the solution in this invention.

[0021] Figure 5 This is a comparison of the relationship between the height and loading pressure of the second and fourth ring cutter undisturbed soil samples of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1—Retaining ring; 2—Lower permeable stone; 3—First thin filter paper; 4—Uncircular soil sample from a ring cutter; 5—Guide ring; 6—Second thin filter paper; 7—Permeable stone. Detailed Implementation

[0023] like Figures 1 to 5 The method shown is a quantitative method for distinguishing between wet collapsibility and solution collapse under different pressures. This method includes the following steps: Step 1: Sampling and Preparation of Uncircular Soil Samples: Take one undisturbed soil sample from the soil layer to be evaluated and prepare four samples at heights of [missing information]. The undisturbed soil samples from the ring cutter are the first ring cutter undisturbed soil sample, the second ring cutter undisturbed soil sample, the third ring cutter undisturbed soil sample, and the fourth ring cutter undisturbed soil sample. It should be noted that when preparing undisturbed soil samples using ring cutters, an ultra-thin soil sampler with authorization announcement number CN214793911 U is used for sampling; alternatively, other soil samplers or manual cutting methods can be used to collect one undisturbed soil sample from the soil layer to be determined. Then, a soil cutting knife and four ring cutters are used to cut the undisturbed soil sample to prepare four ring cutter undisturbed soil samples. The four ring cutter undisturbed soil samples have the same structure and dimensions. The height of the ring cutter used is 20.00 mm, the inner diameter is φ79.8 mm, and the area is 5000 mm². 2 The maximum permissible density difference range for the four undisturbed soil samples obtained by ring cutter is ±0.015 g / cm³. 3 The maximum permissible difference in moisture content is ±1%.

[0024] Step 2: Immersion and Consolidation Tests with Different Solutions: Using distilled water as the solution, an immersion and consolidation test was conducted on the undisturbed soil sample of the first ring cutter under the rated pressure P. The stable settling height of the undisturbed soil sample of the first ring cutter under the rated pressure P was obtained. Simultaneously, saturated distilled water consolidation tests were conducted on the undisturbed soil samples of the second ring cutter under pressure levels 1 to n, obtaining the stable saturated water settlement height of the undisturbed soil samples of the second ring cutter under pressure levels 1 to n. , … Where n is a positive integer and n>2, the nth pressure level is equal to the rated pressure P; Using saturated NaCl solution as the solution, a consolidation test was conducted on the undisturbed soil sample of the third ring cutter under the rated pressure P by immersion in saturated NaCl solution. The stable settling height of the undisturbed soil sample of the third ring cutter under the rated pressure P was obtained. Simultaneously, saturated NaCl solution consolidation tests were conducted on the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n, obtaining the saturated settlement stability height of the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n. , … ; It should be noted that the rated pressure P is 200 kPa, and the value of n is 6. The six pressure levels are 25 kPa, 50 kPa, 75 kPa, 100 kPa, 150 kPa, and 200 kPa, respectively.

[0025] It should be noted that during the saturation consolidation test, the solution was added to carry out the saturation consolidation test up to the rated pressure only after the sedimentation had stabilized under the first-level pressure.

[0026] It should be noted that the stable height of the first ring cutter undisturbed soil sample after immersion in water under rated pressure P refers to the sample height after the first ring cutter undisturbed soil sample has undergone immersion consolidation test and stabilized under rated pressure P.

[0027] Step 3: Correcting the settling stability height under various pressures in the consolidation tests of saturated distilled water and saturated NaCl solution: Under rated pressure, the saturated water settling stability height is equal to the theoretical value of the immersion water settling stability height, and the value directly obtained from the immersion consolidation test... and To ensure that the theoretical values ​​of wet collapse and solution collapse mechanisms are consistent with objective realities, the stable subsidence height under water immersion is used as the benchmark, and correction factors are applied accordingly. and The saturated water settling stability heights under various pressures within the rated pressure range of saturated distilled water and saturated NaCl solution were corrected to obtain the immersion settling stability heights under pressures of levels 1 to n with distilled water as the solution. , … And the stable immersion sinking height under the first to nth pressures using saturated NaCl solution as the solution. , … ; Step 4: Calculate the additional settlement per unit thickness of the undisturbed soil sample under various pressures. The process is as follows: The method for calculating the additional subsidence under various pressure levels is to subtract the corrected submerged subsidence stability height from the unsubmerged subsidence stability height. Therefore, according to the formula... The calculations yielded the results for the first and second ring cutter undisturbed soil samples using distilled water as the solution at the [missing information]. Additional subsidence per unit thickness (unit height) under pressure It can also be said that the first and second ring cutter undisturbed soil samples, which used distilled water as a solution, were in the first... The total subsidence coefficient under pressure level, where, are positive integers and ≤n, For the undisturbed soil sample from the ring cutter, at the first The stable sinking height of the unsubmerged unit under pressure; According to the formula Calculations were performed on the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution in the [missing information]. Additional subsidence per unit thickness under pressure , It should be noted that the saturated NaCl solution, as an soaking or saturated aqueous solution, inhibits the dissolution and migration of crystalline salts in collapsible soil. Therefore, the additional subsidence per unit thickness calculated for the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution as the solution is the collapsible amount per unit thickness under each pressure, i.e., the collapsibility coefficient.

[0028] Step 5: Quantitatively calculate the solution collapse per unit thickness of the undisturbed soil sample under various pressures using the difference method: The additional settlement and total settlement coefficient obtained and corrected from the immersion and saturated consolidation tests using distilled water as the solution for the first and second ring cutter undisturbed soil samples are a combination of wet collapse and solution collapse. The additional settlement and wet collapse coefficient separated from the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution are the wet collapse additional settlement and wet collapse coefficient, according to the formula... The calculations yielded the undisturbed soil sample at the [number]th [year]. Dissolution volume per unit thickness under high pressure This can also be referred to as the solution trap coefficient; Step 6: Determining the dominance of wet collapse and solution collapse under various pressures, the process is as follows: when <0.01 and If the pressure is ≥0.015, the soil layer is determined to be collapsible saline soil under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; when <0.005, 0.01≤ <0.015 and When the pressure is ≥0.015, the soil layer is determined to be saline soil that can be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; When 0.005≤ <0.01, <0.01 and 0.01≤ If the value is less than 0.015, the soil layer is determined to be saline soil that can be considered as collapsible under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; when ≥0.01 and If the pressure is less than 0.015, the soil layer is determined to be saline soil with collapsibility under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; When 0.005≤ <0.01, 0.005< <0.015, and 0.015≤ When <0.025, the soil layer is determined to be saline soil that can be considered as collapsible and soluble under this pressure; when ≥0.01、 When the pressure is ≥0.015, the soil layer is determined to be saline soil with collapsibility and solubility under that pressure. when <0.01, <0.01, and If the pressure is less than 0.01, the soil layer is determined to be saline soil that does not exhibit collapsibility or solubility under that pressure, and is classified as ordinary saline soil. It is used as a deformation coefficient to calculate the deformation of the soil layer it represents; In practice, due to the unique three-phase composition of saline soil, its liquid phase is not water but a saturated salt solution, and the solid phase contains unstable crystalline salts in addition to the solid particles of the soil. The liquid phase can transform into each other due to changes in external conditions. The collapsibility and dissolution mechanisms in saline soil with wet collapsibility are as follows: Collapse mechanism - Under certain pressure, when soil is wetted by water, the soil structure (skeletal particle morphology, connection form and arrangement) is rapidly destroyed, resulting in significant additional settlement; Solution subsidence mechanism - Under certain pressure, due to the dissolution and migration of salts in the soil by water, the crystalline salt particles in the soil are dissolved in the form of solute by the seepage water and carried away with the seepage, resulting in additional subsidence.

[0029] Based on the mechanisms of wet collapse and dissolution, under certain pressure, the salt and saturated salt solution in saline soil with wet collapse properties can be prevented from dissolving and migrating during the immersion process, thus allowing the wet collapse portion to be directly separated.

[0030] The salts in saline soil that dissolve in water are mainly soluble and moderately soluble salts, with the main ion being Na+. + K + Ca 2+ Mg 2+ NH4 + SO4 2- Cl - CO3 2- HCO3 - Based on the solubility and molecular weight of readily soluble and moderately soluble salts, the Na+ concentration per unit volume of water in readily soluble and moderately soluble salt solutions under saturated conditions is... + NH4 + and Cl -The ions account for the largest number, so easily soluble and moderately soluble salts cannot dissolve in saturated NaCl and NH4Cl solutions. Since saturated NH4Cl solutions are unstable and easily decomposed, using saturated NaCl solution as the soaking solution can inhibit the dissolution of easily soluble and moderately soluble salt crystals in saline soil and the conversion between liquid salt solution and crystals in saline soil.

[0031] Therefore, by using saturated NaCl solution as the solution to conduct immersion and consolidation tests on saline soil under a certain pressure, the amount of collapsibility can be directly separated, and the additional settlement deformation per unit thickness obtained is the collapsibility coefficient. Similarly, by using distilled water as the solution to conduct immersion and consolidation tests on saline soil under a certain pressure, the additional settlement deformation per unit thickness, i.e., the total deformation, is defined as the total collapse coefficient, which includes all the dissolution amounts per unit thickness. The dissolution coefficient in wet collapsible soil is obtained using the difference method, thus completing the qualitative and quantitative differentiation between collapsibility and dissolution in wet collapsible soil under a certain pressure. Based on the results of immersion and consolidation tests under a certain pressure, the different collapsibility coefficients and dissolution coefficients under various pressures are calculated, thereby completing the qualitative and quantitative differentiation of collapsibility and dissolution in wet collapsible soil under different pressures.

[0032] It should be noted that by using undisturbed soil samples for testing, the data obtained are more objective and consistent with reality, thus solving the error caused by the damage to the original structure in the remodeling test.

[0033] It should be noted that by using saturated NaCl solution to conduct immersion and saturated consolidation tests, the dissolution of crystalline salts and salt solutions in saline soil during the test was successfully suppressed. This ensured that the original structure of the saline soil was not disturbed and that the collapse was completely separated directly. The data is more objective and consistent with reality, and it solves a problem that has been restricting the geotechnical engineering community.

[0034] It should be noted that by correcting the saturated water settlement stability height under different pressures in the consolidation tests of saturated distilled water and saturated NaCl solution to the immersion stability height, the wet collapse and solution collapse under different pressures were quantitatively distinguished. Formulas for calculating the total settlement coefficient, wet collapse coefficient, and solution collapse coefficient under each pressure after separation were given, which facilitates the quantitative determination of wet collapse and solution collapse under different pressures. Salt washing is not required, the operation is highly operable, the test cycle is short, and it is convenient to achieve objective evaluation of undisturbed soil samples.

[0035] It should be noted that, based on the quantitative distinction between collapsibility and solution collapse under various pressures, the range setting of the collapsibility coefficient, solution collapse coefficient, and total settlement coefficient enables a qualitative determination of the dominance of collapsibility and solution collapse under various pressures. Furthermore, it proposes a method for determining whether to use the total settlement calculation as the amount of solution collapse or collapsibility collapse. This effectively solves the problem of quantitatively distinguishing between collapsibility and solution collapse in collapsible soils in geotechnical engineering, and can thus effectively avoid engineering quality problems, engineering cost problems, and operational problems in saline soil areas.

[0036] In specific implementation, in step two, the four undisturbed soil samples were subjected to immersion and consolidation tests using distilled water and saturated NaCl solution as the solution. The process is as follows: Step 201: Level the consolidation apparatus and simultaneously move the dial indicator head to ensure that the dial indicator pointer can rotate freely and the measuring rod can slide freely. Step 202: Conduct undisturbed soil tests on the four ring cutter specimens, such as... Figure 2 As shown, the consolidation container is first placed in the following order at the bottom: retaining ring 1, lower permeable stone 2, first thin filter paper 3, ring cutter undisturbed soil sample 4, guide ring 5, second thin filter paper 6, upper permeable stone 7, and pressure cover plate. The consolidation container is then placed on the consolidation apparatus platform, and the bottom of the crossbeam of the consolidation apparatus is attached to the top of the pressure cover plate. A dial gauge is then installed at the center of the crossbeam. Step 203: Apply a pre-pressure of 1 kPa to make the four undisturbed soil samples of the ring cutter fully contact their corresponding first bottom permeable stone and first top permeable stone, and adjust the dial gauges corresponding to the four undisturbed soil samples of the ring cutter to the initial reading. Step 204: Apply the first level of pressure to the four undisturbed soil samples from the ring cutter, and read the deformation reading of each undisturbed soil sample from the ring cutter every 30 minutes until the deformation of the four undisturbed soil samples from the ring cutter is stable. When the dial gauge reading of the second undisturbed soil sample after deformation stabilization is inconsistent with the dial gauge reading of the first undisturbed soil sample, the dial gauge reading of the second undisturbed soil sample after deformation stabilization is adjusted to the dial gauge reading of the first undisturbed soil sample; when the dial gauge reading of the fourth undisturbed soil sample after deformation stabilization is inconsistent with the dial gauge reading of the third undisturbed soil sample, the dial gauge reading of the fourth undisturbed soil sample after deformation stabilization is adjusted to the dial gauge reading of the third undisturbed soil sample. Step 205: Perform immersion consolidation tests under rated pressure on the first and third ring cutter undisturbed soil samples according to the method in step a; perform saturated consolidation tests under pressure levels 1 to n on the second and fourth ring cutter undisturbed soil samples according to the method in step b. Step a: Continue to pressurize the first and third ring cutter undisturbed soil samples step by step according to the method in step 204 until the rated pressure is reached. After the deformation of the first and third ring cutter undisturbed soil samples stabilizes under the rated pressure, inject distilled water into the water tank where the first ring cutter undisturbed soil sample is located, up to the height of the top surface of the permeable stone, until the deformation of the first ring cutter undisturbed soil sample stabilizes; inject saturated NaCl solution into the water tank where the third ring cutter undisturbed soil sample is located, up to the height of the top surface of the permeable stone, until the deformation of the third ring cutter undisturbed soil sample stabilizes. Step b: Pour distilled water into the water tank of the consolidation container for the second ring cutter undisturbed soil sample until it reaches the height of the top permeable stone. Pour saturated NaCl solution into the water tank of the consolidation container for the fourth ring cutter undisturbed soil sample until it reaches the height of the top permeable stone. Read the deformation reading of each ring cutter undisturbed soil sample every 30 minutes until the deformation of the ring cutter undisturbed soil sample stabilizes. Gradually increase the pressure of the second ring cutter undisturbed soil sample to the rated pressure until the deformation of the second ring cutter undisturbed soil sample stabilizes. During each pressure increase reading, replace the distilled water in the water tank of the consolidation container for the second ring cutter undisturbed soil sample until it reaches the height of the top permeable stone. Gradually increase the pressure of the fourth ring cutter undisturbed soil sample to the rated pressure until the deformation of the fourth ring cutter undisturbed soil sample stabilizes. During each pressure increase reading, replace the saturated NaCl solution in the water tank of the consolidation container for the fourth ring cutter undisturbed soil sample until it reaches the height of the top permeable stone. Step 206: After the immersion and saturation consolidation tests are completed, remove the four undisturbed soil samples with ring cutters.

[0037] In specific implementation, in step 204, the stabilization condition for the deformation stability of each ring cutter undisturbed soil sample is that the deformation per hour is no more than 0.01 mm.

[0038] In specific implementation, in step a, in order to ensure that the crystalline salt and salt solution contained in the first ring cutter undisturbed soil sample are completely dissolved, and in order to ensure that the crystalline salt and salt solution contained in the third ring cutter undisturbed soil sample are not dissolved, after the solution is injected into the water tank where the first ring cutter undisturbed soil sample and the third ring cutter undisturbed soil sample are located, the solution in the water tank where each ring cutter undisturbed soil sample is located is replaced at set intervals until the test ends. In step b, to ensure that the crystalline salt and salt solution contained in the second ring cutter undisturbed soil sample are completely dissolved, and to ensure that the crystalline salt and salt solution contained in the fourth ring cutter undisturbed soil sample are not dissolved, after the first stage of pressurization of the second and fourth ring cutter undisturbed soil samples and after the solution is injected into their respective water tanks, the solution in the water tanks of each ring cutter undisturbed soil sample is replaced at set intervals until the end of the test.

[0039] In practice, when replacing the solution in the water tank containing the undisturbed soil sample of the ring cutter, the solution in the water tank containing the undisturbed soil sample of the ring cutter is first drained. When the water level in the water tank containing the undisturbed soil sample of the ring cutter drops to the top surface of the ring cutter, a new solution is injected into the water tank containing the undisturbed soil sample of the ring cutter, so that the water head in the water tank containing the undisturbed soil sample of the ring cutter and the top of the permeable stone are always kept at the same level.

[0040] In specific implementation, before conducting the immersion consolidation test at the rated pressure P on the undisturbed soil sample of the first ring cutter in step two, the undisturbed soil sample of the first ring cutter is pressurized step by step until the rated pressure is reached. This allows us to obtain the settlement stability height of the undisturbed soil sample of the ring cutter under the first to nth pressure levels without immersion. , … .

[0041] In actual use, the stable settlement height of the un-water-immersed soil sample was measured after the undisturbed soil sample under pressure and deformation stabilized.

[0042] In specific implementation, in step three, because the saturated settlement stability height of the undisturbed soil sample under the first level of pressure is equal to its theoretical value of the submerged settlement stability height, that is... equal , equal ; Therefore, according to the formula The correction factor for correcting the results of the consolidation test of the second ring cutter undisturbed soil sample with saturated distilled water was calculated. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the immersion in distilled water and consolidation tests with saturated distilled water. The second ring cutter undisturbed soil sample should be tested on the [date missing]. Corrected immersion sinking stability height under pressure ; According to the formula The correction factor was calculated to correct the results of the consolidation test of the undisturbed soil sample in saturated NaCl solution for the fourth ring cutter. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the consolidation tests with saturated NaCl solution and saturated NaCl solution. The fourth ring cutter undisturbed soil sample was tested on the [missing information - likely a date or time]. Corrected immersion sinking stability height under pressure .

[0043] It should be noted that, = , = .

[0044] In specific implementation, in step six, when the undisturbed soil sample is saline soil that can be considered as collapsible and soluble under this pressure, the saline soil that can be considered as collapsible and soluble under this pressure is divided into saline soil that can be considered as collapsible and saline soil that can be considered as soluble, based on the degree to which collapsibility and soluble deformation dominate the settlement deformation. That is, when 1.5 ≤ At that time, the soil layer was determined to be saline soil that could be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the representative soil layer; when 1.5 > At that time, the soil layer was determined to be saline soil that could be considered as collapsible under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

[0045] In specific implementation, in step six, when the undisturbed soil sample is saline soil exhibiting collapsibility and solution collapse under this pressure, the saline soil is classified into collapsibility-dominated saline soil and solution-dominated saline soil according to the degree of dominance of collapsibility and solution collapse in settlement deformation, i.e., when 1.5 ≤ At that time, the soil layer was determined to be saline soil dominated by collapsibility under that pressure. The collapse amount is calculated using the collapse coefficient; when 1.5 > At that time, the soil layer was determined to be saline soil dominated by dissolution under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

[0046] like Figure 3 As shown in this embodiment, the horizontal axis represents the loading pressure, and the vertical axis represents the height value. , , , , , This refers to the stable settlement height of the undisturbed soil sample from the first ring cutter under various pressure levels without being submerged in water. , , , , , This refers to the stable settling height of the undisturbed soil sample from the second ring cutter under various pressure levels saturated with distilled water. , , , , , This refers to the stable sinking height of the modified second ring cutter undisturbed soil sample immersed in distilled water under various pressure levels.

[0047] like Figure 4 As shown in this embodiment, the horizontal axis represents the loading pressure, and the vertical axis represents the height value. , , , , , This refers to the stable settling height of the undisturbed soil sample from the third ring cutter under various pressure levels without being submerged in water. , , , , , This refers to the stable settling height of the undisturbed soil sample from the fourth ring cutter under various pressure levels in a saturated NaCl solution. , , , , , This refers to the stable settling height of the modified fourth ring cutter undisturbed soil sample immersed in saturated NaCl solution under various pressure levels.

[0048] like Figure 5 As shown in this embodiment, the horizontal axis represents the loading pressure, and the vertical axis represents the height value. Figure 5 The diagram clearly illustrates the relationship between the additional settlement of wet subsidence, subsidence, and solution subsidence, making it easy for people to see intuitively.

[0049] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for quantitatively distinguishing between the collapse and the dissolution of a wet collapsible soil under different pressures, characterized by, The method includes the following steps: Step 1: Sampling and Preparation of Uncircular Soil Samples: Take one undisturbed soil sample from the soil layer to be evaluated and prepare four samples at heights of [missing information]. The undisturbed soil samples from the ring cutter are the first ring cutter undisturbed soil sample, the second ring cutter undisturbed soil sample, the third ring cutter undisturbed soil sample, and the fourth ring cutter undisturbed soil sample. Step 2: Immersion and Consolidation Tests with Different Solutions: Using distilled water as the solution, an immersion and consolidation test was conducted on the undisturbed soil sample of the first ring cutter under the rated pressure P. The stable settling height of the undisturbed soil sample of the first ring cutter under the rated pressure P was obtained. Simultaneously, saturated distilled water consolidation tests were conducted on the undisturbed soil samples of the second ring cutter under pressure levels 1 to n, obtaining the stable saturated water settlement height of the undisturbed soil samples of the second ring cutter under pressure levels 1 to n. , … Where n is a positive integer and n>2, the nth pressure level is equal to the rated pressure P; Using saturated NaCl solution as the solution, a consolidation test was conducted on the undisturbed soil sample of the third ring cutter under the rated pressure P by immersion in saturated NaCl solution. The stable settling height of the undisturbed soil sample of the third ring cutter under the rated pressure P was obtained. Simultaneously, saturated NaCl solution consolidation tests were conducted on the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n, obtaining the saturated settlement stability height of the undisturbed soil samples of the fourth ring cutter under pressure levels 1 to n. , … ; Step 3: Correcting the settling stability height under various pressures in the consolidation tests of saturated distilled water and saturated NaCl solution: Using the settling stability height under immersion as a benchmark, respectively, through correction factors... and The saturated water settling stability heights under various pressures within the rated pressure range of saturated distilled water and saturated NaCl solution were corrected to obtain the immersion settling stability heights under pressures of levels 1 to n with distilled water as the solution. , … And the stable immersion height under the first to nth pressures using saturated NaCl solution as the solution. , … ; Step 4: Calculate the additional settlement per unit thickness of the undisturbed soil sample under various pressures. The process is as follows: According to the formula The calculations yielded the results for the first and second ring cutter undisturbed soil samples using distilled water as the solution at the [missing information]. Additional subsidence per unit thickness under pressure ,in, are positive integers and ≤n, For the undisturbed soil sample from the ring cutter, at the first The stable sinking height of the unsubmerged unit under pressure; According to the formula Calculations were performed on the third and fourth ring cutter undisturbed soil samples using saturated NaCl solution in the [missing information]. Additional subsidence per unit thickness under pressure ; Step 5: Quantitatively calculate the solution collapse per unit thickness of the undisturbed soil sample under various pressures using the difference method: According to the formula... The calculations yielded the undisturbed soil sample at the [number]th [year]. Dissolution volume per unit thickness under high pressure ; Step 6: Determining the dominance of wet collapse and solution collapse under various pressures, the process is as follows: when <0.01 and If the pressure is ≥0.015, the soil layer is determined to be collapsible saline soil under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; when <0.005, 0.01≤ <0.015 and When the pressure is ≥0.015, the soil layer is determined to be saline soil that can be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the soil layer it represents; When 0.005≤ <0.01, <0.01 and 0.01≤ If the value is less than 0.015, the soil layer is determined to be saline soil that can be considered as collapsible under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; when ≥0.01 and If the pressure is less than 0.015, the soil layer is determined to be saline soil with collapsibility under that pressure. It is used as a solution collapse coefficient to calculate the solution collapse amount of the representative soil layer; When 0.005≤ <0.01, 0.005< <0.015, and 0.015≤ When <0.025, the soil layer is determined to be saline soil that can be considered as collapsible and soluble under this pressure; when ≥0.01、 When the pressure is ≥0.015, the soil layer is determined to be saline soil with collapsibility and solubility under that pressure. when <0.01, <0.01, and If the pressure is less than 0.01, the soil layer is determined to be saline soil that does not exhibit collapsibility or solubility under that pressure, and is classified as ordinary saline soil. It is used as a deformation coefficient to calculate the deformation of the soil layer it represents; In step two, before conducting the immersion consolidation test at the rated pressure P on the undisturbed soil sample of the first ring cutter, the undisturbed soil sample of the first ring cutter is pressurized step by step until the rated pressure is reached. This allows us to obtain the settlement stability height of the undisturbed soil sample of the ring cutter under the first to nth pressure levels without immersion. , … ; In step three, according to the formula The correction factor for correcting the results of the consolidation test of the second ring cutter undisturbed soil sample with saturated distilled water was calculated. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the immersion in distilled water and consolidation tests with saturated distilled water. The second ring cutter undisturbed soil sample should be tested on the [date missing]. Corrected immersion sinking stability height under pressure ; According to the formula The correction factor was calculated to correct the results of the consolidation test of the undisturbed soil sample in saturated NaCl solution for the fourth ring cutter. Among them, when 0.8 < If the value is less than 1.2, the test data is acceptable; otherwise, repeat the consolidation tests with saturated NaCl solution and saturated NaCl solution. The fourth ring cutter undisturbed soil sample was tested on the [missing information - likely a date or time]. Corrected immersion sinking stability height under pressure ; The maximum allowable difference range of the density of the four-ring knife undisturbed soil sample is ±0.015 g / cm 3 The maximum allowable difference range of the moisture content is ±1%.

2. The method for quantitatively distinguishing between wet collapse and solution collapse of collapsible soil under different pressures according to claim 1, characterized in that: In step six, when the undisturbed soil sample is saline soil that can be considered as collapsible and soluble under this pressure, the saline soil is classified into saline soil that can be considered as collapsible and saline soil that can be considered as soluble based on the degree to which collapsibility and soluble collapse dominate the settlement deformation. That is, when 1.5 ≤ At that time, the soil layer was determined to be saline soil that could be considered collapsible under that pressure. It is used as a collapsibility coefficient to calculate the collapsibility of the representative soil layer; when 1.5 > At that time, the soil layer was determined to be saline soil that could be considered as collapsible under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

3. The method for quantitatively distinguishing between wet collapse and solution collapse of collapsible soil under different pressures according to claim 1, characterized in that: In step six, when the undisturbed soil sample is saline soil exhibiting collapsibility and solution collapse under this pressure, the saline soil is classified into collapsibility-dominated saline soil and solution-dominated saline soil according to the degree of dominance of collapsibility and solution collapse in settlement deformation, i.e., when 1.5 ≤ At that time, the soil layer was determined to be saline soil dominated by collapsibility under that pressure. The collapse amount is calculated using the collapse coefficient; when 1.5 > At that time, the soil layer was determined to be saline soil dominated by dissolution under that pressure. It is used as the solution collapse coefficient to calculate the solution collapse amount of the soil layer it represents.

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