Prediction method for undisturbed loess consolidation drainage shear strength parameter based on structure

Abstract

The invention discloses a structural-based undisturbed loess consolidation drainage shear strength parameter prediction method, belongs to the technical field of geotechnical engineering investigation, and can solve the problems of long time consumption, complex operation and relatively high cost of an existing mode. The method comprises the following steps: firstly, determining initial structural characterization parameter data, consolidation drainage shear strength parameter data and plasticity index data of undisturbed loess in a plurality of test areas, and respectively constructing a first quantitative relationship and a second quantitative relationship between the initial structural characterization parameter and the consolidation drainage shear strength parameter and between the initial structural characterization parameter and the plasticity index; then determining an initial structural characterization parameter predicted value of the undisturbed loess in the target area according to the plasticity index measured value of the undisturbed loess in the target area and the second quantitative relation; and finally, according to the initial structural representation parameter predicted value and the first quantitative relationship, determining a consolidation drainage shear strength parameter predicted value of the undisturbed loess in the target area. The method is used for predicting the consolidation drainage shear strength parameter of the undisturbed loess.

Description

Technical Field

[0001] This invention relates to a method for predicting the consolidated drainage shear strength parameters of undisturbed loess based on structural characteristics, belonging to the field of geotechnical engineering investigation technology. Background Technology

[0002] Uncirculated loess is widely distributed in Northwest my country and serves as the core bearing medium in engineering projects such as highways, railways, and building foundations. Due to the rugged terrain of the western region, infrastructure construction often requires layering and remolding loess on top of the uncirculated loess layer in gully areas to create a level construction site. During this construction process, the deep uncirculated loess undergoes long-term consolidation and drainage. It is important to note that in such projects, the consolidated drained shear strength parameters (cohesion and internal friction angle) of the uncirculated loess are crucial design bases for calculating foundation bearing capacity and analyzing the stability of fill slopes, directly affecting the safety, stability, and economic efficiency of the project. Therefore, how to quickly and accurately determine these strength parameters has always been a research hotspot in geotechnical and geological engineering, and a core issue of concern for engineering designers and construction personnel.

[0003] To obtain the consolidated drained shear strength parameters (cohesion and internal friction angle) of undisturbed loess, the commonly used test method is the indoor consolidated drained triaxial shear test. Although this method can directly measure the strength parameters, it has significant limitations: on the one hand, the test cycle is long, often requiring several days to several weeks to complete a single test on a single specimen, which is difficult to meet the efficiency requirements of large-scale engineering surveys; on the other hand, this test relies on a sophisticated triaxial shear apparatus, which is complex to operate and has high equipment and labor costs, making it less applicable to small-scale projects or preliminary survey stages. Summary of the Invention

[0004] This invention provides a method for predicting the consolidated drainage shear strength parameters of undisturbed loess based on structure, which can solve the problems of long time consumption, complex operation, and high equipment and labor costs of existing methods.

[0005] This invention provides a method for predicting the consolidated drained shear strength parameters of undisturbed loess based on its structure, the method comprising:

[0006] S1. Based on the one-dimensional consolidation test results of undisturbed loess and remolded loess in multiple test areas, the initial structural characterization parameters of undisturbed loess in multiple test areas were determined.

[0007] S2. Determine the consolidation drained shear strength parameter data of undisturbed loess in multiple test areas, and construct a first quantitative relationship between the initial structural characterization parameter data and the consolidation drained shear strength parameter data of undisturbed loess.

[0008] S3. Determine the plasticity index data of undisturbed loess in multiple test areas, and construct a second quantitative relationship between the plasticity index of undisturbed loess and the initial structural characterization parameters based on the plasticity index data and the initial structural characterization parameter data.

[0009] S4. Determine the measured value of the plasticity index of the original loess in the target area, and determine the predicted value of the initial structural characterization parameters of the original loess in the target area based on the measured value of the plasticity index and the second quantitative relationship.

[0010] S5. Based on the predicted values ​​of the initial structural characterization parameters and the first quantitative relationship, determine the predicted values ​​of the consolidated drained shear strength parameters of the undisturbed loess in the target area.

[0011] Optionally, S1 specifically includes:

[0012] One-dimensional consolidation tests were conducted on undisturbed loess and remolded loess in each test area. The compression curves of undisturbed loess and remolded loess in each test area were obtained. The abscissa value of the initial intersection point of the two compression curves was recorded as the initial stress, and the abscissa value of the inflection point of the compression curve of undisturbed loess was recorded as the yield stress.

[0013] Based on the initial stress and the yield stress, the initial structural characterization parameters of the undisturbed loess in the corresponding test area are determined.

[0014] Optionally, based on the initial stress and the yield stress, the initial structural characterization parameters of the undisturbed loess in the corresponding test area are determined, specifically including:

[0015] The difference between the yield stress and the initial stress is calculated, and the ratio of the difference to the yield stress is used as the initial structural characterization parameter data of the undisturbed loess in the corresponding test area.

[0016] Optionally, the determination of consolidated drained shear strength parameter data of undisturbed loess in multiple test areas in S2 specifically includes:

[0017] Consolidated drained shear tests were conducted on undisturbed loess from multiple test areas to obtain consolidated drained shear strength parameters for undisturbed loess from each test area.

[0018] Optionally, the consolidated drainage shear strength parameter data includes cohesion data and internal friction angle data;

[0019] The first quantitative relationship between the initial structural characterization parameters and the consolidated drained shear strength parameters of undisturbed loess, constructed in step S2 based on the initial structural characterization parameter data and the consolidated drained shear strength parameter data, specifically includes:

[0020] Based on the initial structural characterization parameter data and the cohesion data, a first relationship between the initial structural characterization parameters and cohesion of undisturbed loess is constructed, and based on the initial structural characterization parameter data and the internal friction angle data, a second relationship between the initial structural characterization parameters and the internal friction angle of undisturbed loess is constructed.

[0021] Optionally, based on the initial structural characterization parameter data and the cohesion data, a first relationship between the initial structural characterization parameters and cohesion of undisturbed loess is constructed, specifically including:

[0022] Linear fitting is performed on the initial structural characterization parameter data and the cohesion data to obtain the first relationship between the initial structural characterization parameters and cohesion of the undisturbed loess; the first relationship is a univariate linear regression equation.

[0023] Optionally, based on the initial structural characterization parameter data and the internal friction angle data, a second relationship between the initial structural characterization parameters and the internal friction angle of undisturbed loess is constructed, specifically including:

[0024] Polynomial fitting is performed on the initial structural characterization parameter data and the internal friction angle data to obtain a second relationship between the initial structural characterization parameters and the internal friction angle of the undisturbed loess. The second relationship is a quadratic equation in one variable.

[0025] Optionally, determining the plasticity index data of undisturbed loess in multiple test areas in S3 specifically includes:

[0026] Liquid limit and plastic limit tests were conducted on undisturbed loess from multiple test areas to obtain plasticity index data for undisturbed loess from each test area.

[0027] Optionally, the second quantitative relationship between the plasticity index and the initial structural characterization parameters of undisturbed loess, constructed in step S3 based on the plasticity index data and the initial structural characterization parameter data, specifically includes:

[0028] Linear fitting is performed on the plasticity index data and the initial structural characterization parameter data to obtain a second quantitative relationship between the plasticity index and the initial structural characterization parameter of the undisturbed loess; the second quantitative relationship is a univariate linear regression equation.

[0029] Optionally, the predicted value of the consolidated drainage shear strength parameter includes the predicted value of cohesion and the predicted value of internal friction angle;

[0030] S5 specifically includes:

[0031] Substituting the predicted values ​​of the initial structural characterization parameters into the first relational expression yields the predicted cohesion value of the undisturbed loess in the target area. Substituting the predicted values ​​of the initial structural characterization parameters into the second relational expression yields the predicted internal friction angle value of the undisturbed loess in the target area.

[0032] The beneficial effects that this invention can produce include:

[0033] The present invention provides a method for predicting the consolidated drained shear strength parameters of undisturbed loess based on structural characteristics. This method is simple, convenient, and highly practical. In actual prediction, only conventional liquid and plastic limit tests of undisturbed loess samples from the target area are required to determine the liquid limit of the undisturbed loess. ) and plastic limit ( ). To obtain the plasticity index ( ) of the original loess in the target area. After that, the consolidated drained shear strength parameters of undisturbed loess can be calculated by substituting them into the constructed quantitative relationship. This method has a detailed derivation process, clear physical and mechanical concepts, and a high degree of formula refinement, thus exhibiting high accuracy in calculating the consolidated drained shear strength parameters of undisturbed loess. Simultaneously, this method significantly shortens the experimental time and substantially reduces experimental costs, thereby lowering project costs and shortening the construction period. Attached Figure Description

[0034] Figure 1 The flowchart shows the method for predicting the structurally based, drained shear strength parameters of undisturbed loess consolidation required for embodiments of the present invention.

[0035] Figure 2 This is a schematic diagram illustrating the original loess structure required for embodiments of the present invention;

[0036] Figure 3 A schematic diagram illustrating the acquisition of initial structural characterization parameters for undisturbed loess in Xi'an and Yan'an, provided for embodiments of the present invention;

[0037] Figure 4 A schematic diagram illustrating the acquisition of cohesion and internal friction angle of undisturbed loess in Xi'an and Yan'an, provided for embodiments of the present invention;

[0038] Figure 5 A schematic diagram illustrating the relationship between initial structural characterization parameters and cohesion and internal friction angle provided for embodiments of the present invention;

[0039] Figure 6 A schematic diagram illustrating the relationship between initial structural characterization parameters and plasticity index provided in an embodiment of the present invention;

[0040] Figure 7 A comparison diagram of the measured and predicted values ​​of the consolidated drained shear strength parameters of undisturbed loess provided in an embodiment of the present invention. Detailed Implementation

[0041] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0042] The consolidated drained shear strength parameters (including cohesion and internal friction angle) of undisturbed loess mainly depend on its natural structure, which can be described and expressed by simple and rapid one-dimensional consolidation test results. Therefore, this invention attempts to propose initial structural characterization parameters for undisturbed loess based on one-dimensional consolidation test results, and establish a quantitative relationship between these initial structural characterization parameters and the consolidated drained shear strength parameters of undisturbed loess, in order to achieve a shear strength parameter prediction method that balances efficiency and accuracy. This method can overcome the limitations of traditional triaxial shear tests and provide technical support for the efficient conduct of geotechnical engineering investigations and the scientific design of foundations.

[0043] Specifically, embodiments of the present invention provide a method for predicting the consolidated drained shear strength parameters of undisturbed loess based on its structure, such as... Figure 1 As shown, the method includes:

[0044] S1. Based on the one-dimensional consolidation test results of undisturbed loess and remolded loess in multiple test areas, the initial structural characterization parameters of undisturbed loess in multiple test areas were determined.

[0045] Specifically, it includes:

[0046] (1) One-dimensional consolidation tests were conducted on the original loess and remolded loess in each test area to obtain the compression curves of the original loess and remolded loess in each test area. The abscissa value of the initial intersection point of the two compression curves was recorded as the initial stress, and the abscissa value of the inflection point of the compression curve of the original loess was recorded as the yield stress.

[0047] (2) Based on the initial stress and yield stress, determine the initial structural characterization parameters of the original loess in the corresponding test area.

[0048] Specifically, the difference between the yield stress and the initial stress is calculated, and the ratio of the difference to the yield stress is used as the initial structural characterization parameter data of the undisturbed loess in the corresponding test area.

[0049] Uncirculated loess from multiple test areas was carefully cut into consolidated specimens with a diameter of 6.18 cm and a height of 2 cm. During specimen preparation, the moisture content, specific gravity, and mass of the uncirculated loess were measured (since the volume was known, the specimen density could be obtained). Based on these parameters, the initial void ratio of the uncirculated loess could be calculated. The prepared uncirculated loess specimens were placed on a consolidation apparatus for a one-dimensional consolidation test. During the test, the uncirculated loess specimens were subjected to staged loading, and the deformation of the specimens was measured during each loading stage (the change in void ratio could be calculated from the change in deformation). Finally, the compression curve of the uncirculated loess specimens, i.e., the curve between void ratio and load, was obtained.

[0050] During the preparation of undisturbed loess samples, many broken soil samples are generated. These broken soil samples are collected and thoroughly crushed using a small hammer to eliminate their structural defects. An equal mass of reconstituted loess is weighed and filled into a specific mold (6.18 cm in diameter and 2 cm in height), then slowly compacted to prepare the reconstituted loess sample. Since the density, specific gravity, and moisture content of the undisturbed and reconstituted loess samples are identical, their initial void ratios are the same. The prepared reconstituted loess sample is placed on a consolidation apparatus, and a one-dimensional consolidation test is performed to obtain the compression curve of the reconstituted loess sample, i.e., the curve between void ratio and load.

[0051] Figure 2 Compression curves for undisturbed and remolded loess samples from Xi'an are presented. Due to space limitations, compression curves for undisturbed and remolded loess from Yan'an, Qinghai, and Yulin are not provided in this invention. Figure 2 It can be seen that under low stress conditions (i.e., initial stress) Under these conditions, the compression curves of undisturbed loess and remolded loess in Xi'an intersect at point A (the initial intersection point). As the overlying stress increases, the void ratio of undisturbed loess in Xi'an gradually decreases in the early stages. However, when the stress exceeds a critical value, the void ratio rapidly decreases. In geotechnical and geological engineering, the Casagrande method is used to determine this critical value: two straight lines are plotted on the early and late compression curves, respectively, which intersect at point B (the inflection point of the compression curve of undisturbed loess). The vertical stress (the value on the horizontal axis) corresponding to point B is the yield stress of the soil sample. When the overlying stress is less than At stage AB, the undisturbed soil sample is in the elastic stage; when the upper stress exceeds the yield stress... Afterwards (BF stage), the structure of the undisturbed loess begins to collapse and break down, after which it begins to undergo plastic deformation. For remolded loess, due to the lack of structure, the compressibility index remains almost constant under overlying stress, resulting in a straight line (AF curve) until it intersects with the undisturbed loess compression curve at point F. It should be noted that at point F, the internal structure of the undisturbed loess is completely destroyed, exhibiting the characteristics of remolded loess.

[0052] This invention defines initial structural characterization parameters based on the vertical stresses corresponding to points A (i.e., the initial intersection point) and B (i.e., the inflection point of the compression curve of the undisturbed loess). (Similar to the length of line segment AB), the calculation formula is formula (1). When the stress exceeds the yield stress... Afterwards (vertical stress corresponding to point B), assuming that the undisturbed loess and the remolded loess will exhibit the same amount of deformation. To achieve this deformation, the effective stress required to be applied to the remolded loess is: (Vertical stress corresponding to point C). For undisturbed loess, assuming it lacks structure, its occurrence... The effective stress required for deformation is the effective stress corresponding to point E. However, due to the structural nature of the undisturbed loess, it will rapidly deteriorate, resulting in significant deformation of the soil sample. Therefore, only the effective stress corresponding to point D needs to be applied to the sample. That is, it will appear Deformation. Based on the effective stresses corresponding to points C and D, parameters for characterizing the post-deformation structure of loess were defined. (Similar to the length of the straight line segment CD), see formula (2).

[0053] (1)

[0054] (2)

[0055] The structural description method and constructed characterization parameters proposed in this invention have clear physical meanings: the structural characterization parameters of undisturbed loess are at their maximum values ​​in stage AB, corresponding to the maximum straight-line distance between AB. As the applied stress gradually increases (stage BF), the structure of the undisturbed loess gradually deteriorates, and the values ​​of the structural characterization parameters gradually decrease until they reach 0 (corresponding to the complete destruction of the undisturbed loess structure at point F, exhibiting remodeled loess characteristics). It is important to emphasize that during the shearing process, the consolidation drained shear stress of the undisturbed loess first gradually increases to a peak value, and then gradually decreases. The magnitude of the shear stress is often determined by the structure of the undisturbed loess. The change process of shear stress is equivalent to the destruction process of the natural structure: when the structural characterization parameters of the undisturbed loess are at their maximum, they correspond to the peak value of the consolidation drained shear stress of the undisturbed loess. As the structure of the undisturbed loess deteriorates, the structural characterization parameters gradually decrease, thus the shear stress of the undisturbed loess gradually decreases in the later stages of shearing. Based on the consolidated drained shear data of undisturbed loess, a Mohr stress circle can be plotted. The intersection of the tangent of the stress circle and the Mohr stress circle is the peak shear stress. Therefore, the slope (internal friction angle) and intercept (cohesion) of the tangent are necessarily closely related to the initial structural characterization parameters (i.e., the maximum values) of the undisturbed loess.

[0056] refer to Figure 2 The method described herein involves conducting conventional one-dimensional consolidation tests on undisturbed loess from different regions (such as Yulin loess in northern Shaanxi, Yan'an loess, Bailuyuan loess in Xi'an, Lanzhou loess, Qinghai loess, and Luoyang loess), thereby determining their respective initial structural characterization parameters. (Maximum value of structural characterization parameter), see Figure 3 Due to space limitations, this invention only uses original loess data from Xi'an and Yan'an as examples.

[0057] S2. Determine the consolidated drained shear strength parameters of undisturbed loess in multiple test areas, and construct the first quantitative relationship between the initial structural characterization parameters and the consolidated drained shear strength parameters of undisturbed loess based on the initial structural characterization parameters and the consolidated drained shear strength parameters.

[0058] The above-mentioned determination of the consolidated drained shear strength parameters of undisturbed loess in multiple test areas is specifically as follows: consolidated drained shear tests were conducted on undisturbed loess in multiple test areas to obtain the consolidated drained shear strength parameters of undisturbed loess in each test area.

[0059] Consolidated drainage shear strength parameters include cohesion data and internal friction angle data.

[0060] The above-mentioned first quantitative relationship between the initial structural characterization parameters and the consolidated drained shear strength parameters of undisturbed loess, constructed based on initial structural characterization parameter data and consolidated drained shear strength parameter data, specifically includes:

[0061] (1) Based on the initial structural characterization parameter data and cohesion data, construct the first relationship between the initial structural characterization parameters and cohesion of the original loess.

[0062] Specifically, linear fitting is performed on the initial structural characterization parameter data and cohesion data to obtain the first relationship between the initial structural characterization parameters and cohesion of the undisturbed loess; the first relationship is a univariate linear regression equation.

[0063] (2) Based on the initial structural characterization parameter data and internal friction angle data, a second relationship between the initial structural characterization parameters and internal friction angle of undisturbed loess is constructed.

[0064] Specifically, polynomial fitting is performed on the initial structural characterization parameter data and internal friction angle data to obtain the second relationship between the initial structural characterization parameters and internal friction angle of the undisturbed loess. The second relationship is a quadratic equation in one variable.

[0065] Consolidated drained triaxial shear tests were conducted on undisturbed loess from different regions (Yulin loess in northern Shaanxi, Yan'an loess, Bailuyuan loess in Xi'an, Lanzhou loess, Qinghai loess, and Luoyang loess, etc.) using a GDS triaxial apparatus. Due to space limitations, this invention only uses data from undisturbed loess in Xi'an and Yan'an as examples. Based on the triaxial shear data, a Mohr's stress circle was plotted, and the consolidated drained shear strength parameters (cohesion data and internal friction angle data) of the undisturbed loess were obtained, as shown in [reference needed]. Figure 4 As shown.

[0066] Based on the initial structural characterization parameters and consolidated drained shear strength parameters, a first quantitative relationship was established between the initial structural characterization parameters and the consolidated drained shear strength parameters (cohesion and internal friction angle) of undisturbed loess samples. (See...) Figure 5 Formulas (3) and (4) are used. Among them, the relationship between cohesion and the initial structural characterization parameters is a linear regression equation; the relationship between the internal friction angle and the initial structural characterization parameters is a quadratic equation.

[0067] (3)

[0068] (4)

[0069] S3. Determine the plasticity index data of undisturbed loess in multiple test areas, and construct a second quantitative relationship between the plasticity index and the initial structural characterization parameters of undisturbed loess based on the plasticity index data and the initial structural characterization parameters data.

[0070] The above-mentioned determination of the plasticity index data of undisturbed loess in multiple test areas is specifically as follows: liquid limit and plastic limit tests were conducted on undisturbed loess in multiple test areas to obtain the plasticity index data of undisturbed loess in each test area.

[0071] The above-mentioned second quantitative relationship between the plasticity index and the initial structural characterization parameters of undisturbed loess is constructed based on the plasticity index data and the initial structural characterization parameter data. Specifically, the plasticity index data and the initial structural characterization parameter data are linearly fitted to obtain the second quantitative relationship between the plasticity index and the initial structural characterization parameters of undisturbed loess; the second quantitative relationship is a univariate linear regression equation.

[0072] Liquid limit and plastic limit tests were conducted on undisturbed loess in multiple test areas to determine the liquid limit (…). ) and plastic limit ( ), and thus the plasticity index of each undisturbed loess sample can be obtained ( )data.

[0073] Then, linear fitting was performed on the initial structural characterization parameter data and plasticity index data to obtain a second quantitative relationship between the plasticity index of undisturbed loess and the initial structural characterization parameters, as shown in [reference needed]. Figure 6 And formula (5); the second quantitative relationship is a univariate linear regression equation.

[0074] (5)

[0075] Based on formulas (3), (4) and (5), this invention finally establishes the relationship between the shear strength parameter and the plasticity index of undisturbed loess.

[0076] S4. Determine the measured value of the plasticity index of the original loess in the target area, and determine the predicted value of the initial structural characterization parameters of the original loess in the target area based on the measured value of the plasticity index and the second quantitative relationship.

[0077] In this embodiment of the invention, the measured value of the plasticity index of the original loess in the target area is determined by indoor liquid limit and plastic limit tests.

[0078] Substituting the measured value of the plasticity index into formula (5), the initial structural characterization parameters of the undisturbed loess can be determined. Predicted value.

[0079] S5. Based on the predicted values ​​of the initial structural characterization parameters and the first quantitative relationship, determine the predicted values ​​of the consolidated drained shear strength parameters of the undisturbed loess in the target area.

[0080] The predicted values ​​of shear strength parameters for consolidated drainage include predicted values ​​of cohesion and internal friction angle;

[0081] S5 specifically includes:

[0082] Substituting the predicted values ​​of the initial structural characterization parameters into the first relational expression yields the predicted value of the cohesion of the undisturbed loess in the target area. Substituting the predicted values ​​of the initial structural characterization parameters into the second relational expression yields the predicted value of the internal friction angle of the undisturbed loess in the target area.

[0083] Initial structural characterization parameters The predicted value is expressed as formula (3), and the cohesion of the original loess in the target area is obtained. Predicted values; initial structural characterization parameters Substituting the predicted value into formula (4), the internal friction angle of the undisturbed loess in the target area is obtained. Predicted value.

[0084] Figure 7 A comparison between measured and predicted values ​​of the consolidated drained shear strength parameters of undisturbed loess is presented. The figure shows a good agreement between the measured and predicted values, indicating that the strength parameter prediction method proposed in this invention has good technical effectiveness.

[0085] Based on the above-described invention and calculation steps, it can be seen that the present invention has the following advantages:

[0086] (1) The method for predicting the consolidated drainage shear strength parameters of undisturbed loess based on structural construction given in this invention has a detailed derivation process, clear physical and mechanical concepts, and a high degree of formula refinement. Therefore, it has high accuracy in calculating the consolidated drainage shear strength parameters of undisturbed loess.

[0087] (2) When using the formula in this invention, only the liquid limit test is required. After obtaining the plasticity index of the original loess, the consolidation drainage shear strength parameters of the original loess can be calculated. This greatly shortens the test time and significantly reduces the test cost, which can reduce the project cost and shorten the construction period to a certain extent.

[0088] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for predicting the consolidated drained shear strength parameters of undisturbed loess based on its structure, characterized in that, The method includes: S1. Based on the one-dimensional consolidation test results of undisturbed loess and remolded loess in multiple test areas, the initial structural characterization parameters of undisturbed loess in multiple test areas were determined. S2. Determine the consolidation drained shear strength parameter data of undisturbed loess in multiple test areas, and construct a first quantitative relationship between the initial structural characterization parameter data and the consolidation drained shear strength parameter data of undisturbed loess. S3. Determine the plasticity index data of undisturbed loess in multiple test areas, and construct a second quantitative relationship between the plasticity index of undisturbed loess and the initial structural characterization parameters based on the plasticity index data and the initial structural characterization parameter data. S4. Determine the measured value of the plasticity index of the original loess in the target area, and determine the predicted value of the initial structural characterization parameters of the original loess in the target area based on the measured value of the plasticity index and the second quantitative relationship. S5. Based on the predicted values ​​of the initial structural characterization parameters and the first quantitative relationship, determine the predicted values ​​of the consolidated drained shear strength parameters of the undisturbed loess in the target area.

2. The method according to claim 1, characterized in that, S1 specifically includes: One-dimensional consolidation tests were conducted on undisturbed loess and remolded loess in each test area. The compression curves of undisturbed loess and remolded loess in each test area were obtained. The abscissa value of the initial intersection point of the two compression curves was recorded as the initial stress, and the abscissa value of the inflection point of the compression curve of undisturbed loess was recorded as the yield stress. Based on the initial stress and the yield stress, the initial structural characterization parameters of the undisturbed loess in the corresponding test area are determined.

3. The method according to claim 2, characterized in that, Based on the initial stress and the yield stress, the initial structural characterization parameters of the undisturbed loess in the corresponding test area are determined, specifically including: The difference between the yield stress and the initial stress is calculated, and the ratio of the difference to the yield stress is used as the initial structural characterization parameter data of the undisturbed loess in the corresponding test area.

4. The method according to claim 1, characterized in that, The determination of consolidated drained shear strength parameters of undisturbed loess in multiple test areas in S2 specifically includes: Consolidated drained shear tests were conducted on undisturbed loess from multiple test areas to obtain consolidated drained shear strength parameters for undisturbed loess from each test area.

5. The method according to claim 1, characterized in that, The consolidated drainage shear strength parameter data includes cohesion data and internal friction angle data; The first quantitative relationship between the initial structural characterization parameters and the consolidated drained shear strength parameters of undisturbed loess, constructed in step S2 based on the initial structural characterization parameter data and the consolidated drained shear strength parameter data, specifically includes: Based on the initial structural characterization parameter data and the cohesion data, a first relationship between the initial structural characterization parameters and cohesion of undisturbed loess is constructed, and based on the initial structural characterization parameter data and the internal friction angle data, a second relationship between the initial structural characterization parameters and the internal friction angle of undisturbed loess is constructed.

6. The method according to claim 5, characterized in that, Based on the initial structural characterization parameter data and the cohesion data, a first relationship between the initial structural characterization parameters and cohesion of undisturbed loess is constructed, specifically including: Linear fitting is performed on the initial structural characterization parameter data and the cohesion data to obtain the first relationship between the initial structural characterization parameters and cohesion of the undisturbed loess; the first relationship is a univariate linear regression equation.

7. The method according to claim 5, characterized in that, Based on the initial structural characterization parameter data and the internal friction angle data, a second relationship between the initial structural characterization parameters and the internal friction angle of undisturbed loess is constructed, specifically including: Polynomial fitting is performed on the initial structural characterization parameter data and the internal friction angle data to obtain a second relationship between the initial structural characterization parameters and the internal friction angle of the undisturbed loess. The second relationship is a quadratic equation in one variable.

8. The method according to claim 1, characterized in that, The determination of plasticity index data for undisturbed loess in multiple test areas in S3 specifically includes: Liquid limit and plastic limit tests were conducted on undisturbed loess from multiple test areas to obtain plasticity index data for undisturbed loess from each test area.

9. The method according to claim 1, characterized in that, The second quantitative relationship between the plasticity index and the initial structural characterization parameters of undisturbed loess, constructed in step S3 based on the plasticity index data and the initial structural characterization parameter data, specifically includes: Linear fitting is performed on the plasticity index data and the initial structural characterization parameter data to obtain a second quantitative relationship between the plasticity index and the initial structural characterization parameter of the undisturbed loess; the second quantitative relationship is a univariate linear regression equation.

10. The method according to claim 5, characterized in that, The predicted values ​​of the consolidated drainage shear strength parameters include the predicted values ​​of cohesion and internal friction angle; S5 specifically includes: Substituting the predicted values ​​of the initial structural characterization parameters into the first relational expression yields the predicted cohesion value of the undisturbed loess in the target area. Substituting the predicted values ​​of the initial structural characterization parameters into the second relational expression yields the predicted internal friction angle value of the undisturbed loess in the target area.

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