Construction method of anisotropic de-structured elastic-plastic model of soft clay

Abstract

The invention discloses a construction method of a soft clay anisotropy de-structured elastic-plastic model, and relates to the technical field of geotechnical engineering. The method comprises the following steps: taking an anisotropic elastic-plastic constitutive model S-CLAY1 as a first soft clay anisotropic de-structured elastic-plastic model; constructing a calculation formula of effective stress increment and introducing the first soft clay anisotropy de-structured elastic-plastic model to obtain a second soft clay anisotropy de-structured elastic-plastic model; introducing a size hardening rule into the second soft clay anisotropy de-structured elastic-plastic model to obtain a third soft clay anisotropy de-structured elastic-plastic model; determining conventional parameters and partial softening parameters; and determining the soft clay anisotropy de-structured elastic-plastic model based on the plastic body strain conventional parameter, the plastic body strain partial softening parameter and the plastic body strain third soft clay anisotropy de-structured elastic-plastic model. According to the method, bonding does not need to be considered when soft clay is modeled, so that the modeling difficulty is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering, and particularly relates to a construction method of a soft clay anisotropic destructuration elastoplastic model. BACKGROUND

[0002] Soft clay is a complex engineering material with high compressibility, and the design and construction of buildings and structures on soft clay have become increasingly common. However, due to the complex characteristics of the material, including anisotropy, structure and creep behavior, it is still a challenge to accurately predict the settlement of structures on soft clay. The volumetric hardening law assumes that the expansion of the yield surface is completely driven by the plastic volumetric strain, and ignores the effect of the plastic deviatoric strain. However, soft clay samples at a higher stress ratio seem to exhibit higher compressibility compared to soft clay samples at a lower stress ratio. This indicates that the plastic deviatoric strain may play a certain role in the evolution of soft clay. With the increase of plastic deviatoric strain, the compressibility of soft clay is amplified, and this phenomenon is called deviatoric softening.

[0003] A common method to consider deviatoric softening is to introduce bonding. Soil structure is generated by the arrangement and combination of soil components, and the loss of bonding causes soft clay to change from an undisturbed state to a restructured state, resulting in a decrease in the size of the yield surface. The bonding degradation in the constitutive model is based on the intrinsic compression index rather than the conventional compression index. The intrinsic compression index must be estimated from the linear segment of the compression curve at a high stress level, at which the soil structure is almost completely removed. However, the stress level required to obtain the intrinsic compression index is particularly high, resulting in difficulties in designing an anisotropic destructuration elastoplastic model. SUMMARY

[0004] Therefore, it is necessary to provide a construction method of a soft clay anisotropic destructuration elastoplastic model in view of the above technical problems.

[0005] The present application adopts the following technical scheme: The present application provides a construction method of a soft clay anisotropic destructuration elastoplastic model, comprising: taking an anisotropic elastoplastic constitutive model S-CLAY1 as a first soft clay anisotropic destructuration elastoplastic model; According to the additive decomposition principle of the total strain increment, a calculation formula of the effective stress increment is constructed, the calculation formula of the effective stress increment is introduced into the first soft clay anisotropic destructuration elastoplastic model, and a second soft clay anisotropic destructuration elastoplastic model is obtained; the calculation formula of the effective stress increment is used to describe the elastic behavior of the first soft clay anisotropic destructuration elastoplastic model; The size hardening rule is introduced into the anisotropic destructured elastoplastic model of the plastic strain second soft clay to obtain an anisotropic destructured elastoplastic model of the third soft clay; the size hardening rule of the plastic strain is constructed according to the hardening parameter determining the size of the yield surface and simultaneously depending on the plastic strain and the plastic shear strain; the size hardening rule includes a partial softening parameter; the partial softening parameter of the plastic strain includes the peak plastic shear strain at the beginning of the partial softening, the size hardening parameter and the softening rate parameter; The conventional parameters of the anisotropic destructured elastoplastic model of the third soft clay are determined, and the partial softening parameters of the anisotropic destructured elastoplastic model of the third soft clay are determined through the triaxial undrained test; the conventional parameters of the plastic strain include the compression index, the rebound index, the critical state stress ratio, the Poisson's ratio and the initial specific volume; Based on the conventional parameters of the plastic strain, the partial softening parameters of the plastic strain and the anisotropic destructured elastoplastic model of the third soft clay of the plastic strain, the anisotropic destructured elastoplastic model of the soft clay is determined.

[0006] Preferably, the calculation formula of the plastic strain effective stress increment is: ; Wherein, is the effective stress increment, is the effective stress vector, , is x to the effective normal stress, is y to the effective normal stress, is z to the effective normal stress, is xy to the shear stress, is yz to the shear stress, is zx to the shear stress, is the total stress vector, , is x to the normal strain, is y to the normal strain, is z to the normal strain, is xy to the shear strain, is yz to the shear strain, is zx to the shear strain, is the plastic strain vector, , is x to the plastic normal strain, For y to the plastic positive strain, For z to the plastic positive strain, For xy to the plastic shear strain, For yz to the plastic shear strain, For zx to the plastic shear strain, is the elastic stiffness matrix; The plastic bulk strain elastic stiffness matrix is: ; where, is the elastic stiffness matrix, is the shear modulus, is the Lame constant, , , , is the Poisson's ratio, is the average effective pressure, is the specific volume, is the rebound index, is the elastic bulk modulus.

[0007] Preferably, the formula corresponding to the size hardening law is: ; where, is the increment of , is the hardening parameter that determines the size of the yield surface, , , is the residual size hardening parameter, is the initial size hardening parameter, is the specific volume, is the plastic bulk strain, is the bias softening parameter including the peak plastic shear strain at the onset of bias softening, is the bias softening parameter including the peak plastic shear strain at the onset of bias softening, is the initial size hardening parameter, is the compression index, is the rebound index, is the parameter that controls the rate of softening of the yield surface, is the Heaviside step function, is the shear strain, is the plastic shear strain at which the soft clay starts to exhibit bias softening, is the residual size hardening parameter, , , , for x Towards plastic normal strain, for y Towards plastic normal strain, for z Towards plastic normal strain, For the plastic deviatoric strain vector, For plastic strain, for xy Towards plastic shear strain, for yz Towards plastic shear strain, for zx Towards plastic shear strain.

[0008] Preferably, the plastic body strain compression index and the plastic body strain springback index are both generated by unloading-loading cycle measurement in an isotropic consolidation test; The formula for calculating the stress ratio at the critical strain state of a plastic body is: ; in, The critical stress ratio. This is the critical internal friction angle.

[0009] Preferably, the peak plastic shear strain at the onset of strain softening in the plastic body The results were obtained from the triaxial undrained test and the measurement of the shear band within the triaxial specimen. The formula for calculating the strain softening rate parameter of plastic bodies is: ; in, For softening rate parameters, The softening parameters include the peak plastic shear strain at the onset of softening. This represents the residual plastic shear strain. For when The tolerance between the actual dimensional hardening parameters and the residual dimensional hardening parameters at that time. For shear strain, For residual size hardening parameters, These are the initial size hardening parameters.

[0010] Preferably, the anisotropic destructured elastoplastic model of plastic volume strain soft clay further includes a yield function and a plastic potential function; the formulas corresponding to the plastic volume strain yield function and the plastic volume strain plastic potential function are as follows: ; in, Let be the yield function. Let be the plastic potential function. , hardening parameter for determining the size of the yield surface, critical state stress ratio, geometrically stress ratio line average effective stress at the intersection with the yield surface, hardening parameter for controlling the inclination of the yield surface, component of satisfies the relationship x to the effective normal stress, y to the effective normal stress, z to the effective normal stress, xy to the shear stress, yz to the shear stress, zx to the shear stress, dimensionless bias fabric vector x to the component, dimensionless bias fabric vector y to the component, dimensionless bias fabric vector z to the component, dimensionless bias fabric vector xy to the component, dimensionless bias fabric vector yz to the component, dimensionless bias fabric vector zx to the component.

[0011] The application provides a construction device of a soft clay anisotropic destructuration elastoplastic model, comprising: a first construction module, which is used for taking an anisotropic elastoplastic constitutive model S-CLAY1 as a first soft clay anisotropic destructuration elastoplastic model; a second construction module, which is used for constructing a calculation formula of an effective stress increment according to a principle of additive decomposition of a total strain increment, introducing the calculation formula of the effective stress increment into the first soft clay anisotropic destructuration elastoplastic model, and obtaining a second soft clay anisotropic destructuration elastoplastic model; the calculation formula of the effective stress increment is used for describing an elastic behavior of the first soft clay anisotropic destructuration elastoplastic model; ​​​​​​​​​The third construction module is used for introducing a size hardening rule into the second soft clay anisotropic destructuration elastoplastic model to obtain a third soft clay anisotropic destructuration elastoplastic model; the plastic body strain size hardening rule is constructed according to a hardening parameter that determines the size of a yield surface and simultaneously depends on a plastic body strain and a plastic shear strain; the size hardening rule includes a partial softening parameter; the plastic body strain partial softening parameter includes a peak plastic shear strain at the beginning of partial softening, a size hardening parameter and a softening rate parameter; The first determination module is used for determining conventional parameters of the third soft clay anisotropic destructuration elastoplastic model, and determining partial softening parameters of the third soft clay anisotropic destructuration elastoplastic model through a triaxial undrained test; the plastic body strain conventional parameters include a compression index, a rebound index, a critical state stress ratio, a Poisson's ratio and an initial specific volume; The second determination module is used for determining a soft clay anisotropic destructuration elastoplastic model based on the plastic body strain conventional parameters, the plastic body strain partial softening parameters and the plastic body strain third soft clay anisotropic destructuration elastoplastic model.

[0012] The present application provides a computer readable storage medium, the storage medium stores a computer program, the computer program is executed by a processor to realize the construction method of the soft clay anisotropic destructuration elastoplastic model.

[0013] The present application provides a computer device, including memory, processor and computer program stored in the memory and can run on the processor, the processor executes the program to realize the construction method of the soft clay anisotropic destructuration elastoplastic model.

[0014] The above-mentioned at least one technical scheme adopted by the present application can achieve the following beneficial effects: According to the additive decomposition principle of total strain increment, a calculation formula of effective stress increment is constructed, the calculation formula of effective stress increment is introduced into the anisotropic destructuration elastoplastic model of the first soft clay, and the anisotropic destructuration elastoplastic model of the second soft clay is obtained; the calculation formula of effective stress increment is used to describe the elastic behavior of the anisotropic destructuration elastoplastic model of the first soft clay; the size hardening rule is introduced into the anisotropic destructuration elastoplastic model of the second soft clay, and the anisotropic destructuration elastoplastic model of the third soft clay is obtained; the size hardening rule of the plastic body strain is constructed according to the hardening parameter that determines the size of the yield surface and depends on the plastic body strain and the plastic shear strain; the size hardening rule includes a partial softening parameter; the conventional parameters of the anisotropic destructuration elastoplastic model of the third soft clay are determined, and the partial softening parameter of the anisotropic destructuration elastoplastic model of the third soft clay is determined through the triaxial undrained test; based on the conventional parameter of the plastic body strain, the partial softening parameter of the plastic body strain and the anisotropic destructuration elastoplastic model of the third soft clay of the plastic body strain, the anisotropic destructuration elastoplastic model of the soft clay is determined. The method does not need to consider the bonding when modeling the soft clay, thereby reducing the modeling difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0016] Figure 1 A flowchart of a construction method of an anisotropic destructuration elastoplastic model of soft clay provided by the present application is shown in the figure; Figure 2 The ADSM model provided by the present application is used to simulate the triaxial test of the soft clay in A schematic diagram of the yield surface in the plane; Figure 3 A schematic diagram of the radial regression method provided by the present application is shown in the figure; Figure 4 A flowchart of the implementation of the ADSM model in ABAQUS provided by the present application is shown in the figure; Figure 5 A schematic diagram of determining the initial size of the MCC yield surface provided by the present application is shown in the figure; Figure 6 Schematic diagrams of the simulation results of the CAD2251 test based on MCC, S-CLAY1, S-CLAY1S and ADSM provided by the present application are shown in the figures, wherein, (a) is a change curve diagram of - (b) is a change curve diagram of - ; Figure 7Fig. 1 is a schematic diagram of simulation results of the CAE2544 test based on MCC, S-CLAY1, S-CLAY1S and ADSM provided by the present application, wherein, (a) is a change curve diagram of - (b) is a change curve diagram of - ; Figure 8 Fig. 2 is a schematic diagram of simulation results of the CAD2277 test based on MCC, S-CLAY1, S-CLAY1S and ADSM provided by the present application, wherein, (a) is a change curve diagram of - (b) is a change curve diagram of - ; Figure 9 Fig. 3 is a schematic diagram of the influence of the ADSM simulation results on the CAD2251 provided by the present application, wherein, (a) is a change curve diagram of - (b) is a change curve diagram of - ; Fig. 4 is a schematic diagram of the influence of the ADSM simulation results on the CAD2251 provided by the present application, wherein, (a) is a change curve diagram of Figure 10 - (b) is a change curve diagram of - ; Fig. 5 is a schematic diagram of the Murro test embankment and the underlying sediment layer provided by the present application; Figure 11 Fig. 6 is a schematic diagram of the Murro test embankment monitoring instrument provided by the present application; Figure 12 Fig. 7 is a schematic diagram of the boundary conditions of the finite element model provided by the present application; Figure 13 Fig. 8 is a comparison diagram of the predicted settlement amount and the observed settlement amount under the center line of the roadbed provided by the present application; Figure 14 Fig. 9 is a comparison diagram of the surface observed settlement amount and the predicted settlement amount at different times provided by the present application; Figure 15 Fig. 10 is a comparison diagram of the observed value and the predicted value of the horizontal displacement at different depths provided by the present application; Figure 16 Fig. 11 is a diagram of the settlement at different depths under the center of the embankment changing with time provided by the present application; Figure 17 Fig. 12 is a diagram of the settlement at different depths under the center of the embankment changing with time provided by the present application; Figure 18 ​The distribution of values at different times at the surface The distribution of values at different times at the surface Figure 19 The distribution of values at different times at the surface The distribution of values at different times at the surface Figure 20 The cloud at different times in the soil layer under the embankment provided by the present application , wherein, (a) is the cloud at different times in the soil layer under the embankment , (b) is the cloud at different times in the soil layer under the embankment , (c) and (d) are the clouds in the soil layer under the embankment toe when bubbles are formed ; Figure 21 The construction device schematic diagram of a soft clay anisotropic de-structural elastic-plastic model provided by the present application Figure 22 The computer equipment schematic diagram of a soft clay anisotropic de-structural elastic-plastic model construction method provided by the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below by combining the specific embodiments of the present application with the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] Devices such as desktop computers, servers and notebook computers can execute the scheme of the present application. For the convenience of description, only servers are taken as the execution subjects for description below.

[0019] Soft clay is a complex engineering material with high compressibility. With the continuous development of cities, the design and construction of buildings and structures on soft clay have become more and more common. However, due to the complex characteristics of soft clay, such as anisotropy, structural property and creep behavior, it is still a challenge to accurately predict the settlement of structures on soft clay.

[0020] The development of numerical techniques represented by the finite element method (FEM) has greatly improved the ability to solve this problem, but the accuracy of these numerical techniques depends largely on the constitutive model used. In recent decades, researchers have proposed various constitutive models to capture the basic behavior of soft clay. However, the development of these models inevitably involves a series of simplifications and assumptions.

[0021] Early constitutive models are generally based on a simplification of the isotropic elastoplastic behavior of soft clays, such as the Modified Cam-Clay (MCC). However, due to the asymmetry of clay platelets and the anisotropic stress conditions during the process of sedimentation and consolidation, natural soft clays often exhibit a clear anisotropy. The lack of anisotropy in constitutive models can lead to highly unrealistic predictions of the mechanical response of soft clays. A common approach to consider anisotropy within the standard elastoplastic framework is to introduce a tilted yield surface in the constitutive model. In addition, the anisotropic model should consider the evolution of the yield surface, including rotation and dilatancy, such as the S-CLAY1 model.

[0022] In Cam-Clay family anisotropic models and some others, the dilatancy of the yield surface is generally described by a volumetric hardening law. The volumetric hardening law assumes that the expansion of the yield surface is entirely driven by the plastic volumetric strain, while the effect of the plastic deviatoric strain is ignored. However, soft clay samples seem to exhibit higher compressibility when the stress ratio is high compared to samples at lower stress ratios. This suggests that the plastic deviatoric strain can play a role in the evolution of soft clays. With the increase of plastic deviatoric strain, the compressibility of soft clay is amplified, which is known as deviatoric softening. To consider the effect of deviatoric softening on the evolution of the yield surface, a common approach is to introduce a bonding parameter related to the plastic deviatoric and volumetric strains, typically as in the S-CLAY1S model.

[0023] It is generally accepted that soil structure is generated by the arrangement and bonding of soil constituents. One advantage of introducing bonding is that it can describe the destructuration of soft clays. The loss of bonding transforms soft clays from an undisturbed state to a restructured state, leading to a reduction in the size of the yield surface. It is important to note that the degradation of bonding in destructuration models is based on the intrinsic compression index rather than the conventional compression index. This parameter must be estimated from the linear segment of the compression curve at high stress levels, where the soil structure is almost completely removed. However, obtaining this parameter is challenging because the required stress level can be particularly high, which can cause difficulties during testing.

[0024] The application provides a new anisotropic destructuration softening model (ADSM) of soft clay containing partial softening. The ADSM is an anisotropic destructuration elastoplastic model of soft clay. The model aims to capture the anisotropy, destructuration and partial softening behavior of soft clay. A key advantage of the ADSM is that the destructuration is not represented based on bonding, thereby eliminating the need for an intrinsic compression index. All model parameters can be obtained through standard triaxial drained and undrained tests and consolidation tests, and the parameter determination process is outlined. A numerical implementation of the ADSM is developed based on the finite element software ABAQUS. The effectiveness of the model is verified through numerical simulation of the Otaniemi clay drained triaxial test and settlement prediction of the Murro test embankment.

[0025] The technical solutions provided by the embodiments of the application are described in detail below with reference to the drawings.

[0026] Figure 1 The application provides a construction method of a soft clay anisotropic destructuration elastoplastic model, and the method comprises the following steps. S101: Taking the anisotropic elastoplastic constitutive model S-CLAY1 as a first soft clay anisotropic destructuration elastoplastic model.

[0027] The soft clay anisotropic destructuration elastoplastic model provided by the application is based on the anisotropic elastoplastic constitutive model S-CLAY1. The model is suitable for normally consolidated or slightly overconsolidated soft clay, is consistent with S-CLAY1, and the anisotropy of the soft clay in the ADSM model is defined by a fabric tensor and combined with rotation and size hardening to describe the evolution of the anisotropy. Unlike S-CLAY1, the ADSM model adds partial softening to the size hardening rule to capture the destructuration of the soft clay.

[0028] S102: According to the additive decomposition principle of the total strain increment, a calculation formula of the effective stress increment is constructed, the calculation formula of the effective stress increment is introduced into the first soft clay anisotropic destructuration elastoplastic model, and a second soft clay anisotropic destructuration elastoplastic model is obtained. The calculation formula of the effective stress increment is used to describe the elastic behavior of the first soft clay anisotropic destructuration elastoplastic model.

[0029] According to the additive decomposition principle of the total strain increment, the formula corresponding to the effective stress increment is formula (1): (1) wherein, is the effective stress increment, is the effective stress vector, , isx to the effective normal stress, is y to the effective normal stress, is z to the effective normal stress, is xy to the shear stress, is yz to the shear stress, is zx to the shear stress, is the total stress vector, , is x to the normal strain, is y to the normal strain, is z to the normal strain, is xy to the shear strain, is yz to the shear strain, is zx to the shear strain, is the plastic strain vector, , is x to the plastic normal strain, is y to the plastic normal strain, is z to the plastic normal strain, is xy to the plastic shear strain, is yz to the plastic shear strain, is zx to the plastic shear strain, is the elastic stiffness matrix.

[0030] The elastic stiffness matrix is given by equation (2): (2); where, is the elastic stiffness matrix, is the shear modulus, is the Lame constant, , , , is the Poisson's ratio, is the average effective pressure, is the specific volume, is the rebound index, is the elastic bulk modulus.

[0031] S103: Introducing the size hardening rule in the second soft clay anisotropic destructuration elastoplastic model to obtain a third soft clay anisotropic destructuration elastoplastic model; the plastic strain size hardening rule is constructed according to the hardening parameter determining the size of the yield surface and depending on the plastic strain and plastic shear strain; the size hardening rule includes a partial softening parameter; the plastic strain partial softening parameter includes the peak plastic shear strain at the beginning of partial softening, the size hardening parameter and the softening rate parameter.

[0032] The ASDM model adopts the same yield function as S-CLAY1. Figure 2 The ADSM model provided by the application has the advantages that The in-plane yield surface is shown in Fig. 1. Figure 2 As shown in the figure, the yield function is an inclined ellipse in the stress space, the ASDM model combines the size hardening and rotational hardening two hardening rules, and considers the change of the natural anisotropy of clay with subsequent loading. The associated flow rule is followed.

[0033] The yield function and the plastic potential function correspond to formula (3): (3); wherein, is the yield function, is the plastic potential function, , , , is the hardening parameter determining the size of the yield surface, is the critical state stress ratio, is the average effective stress at the intersection of the stress ratio line and the yield surface, is the hardening parameter controlling the inclination of the yield surface, The components of satisfy the relationship , is the x effective normal stress, is the y effective normal stress, is the z effective normal stress, is the xy shear stress, is the yz shear stress, is the zx shear stress, is the dimensionless partial fabric vector x toward the component, is the dimensionless partial fabric vector y toward the component, is the dimensionless partial fabric vector z toward the component, dimensionless bias fabric vector xy to components, dimensionless bias fabric vector yz to components, dimensionless bias fabric vector zx to components.

[0034] Two hardening rules are introduced in ADSM. First is the size hardening rule, the size of the yield surface is changed by changing the value of . The S-CLAY1 constitutive model assumes only depends on plastic volumetric strain, similar to the Modified Cam-Clay (MCC). Different from S-CLAY1 and MCC, in ADSM, it is assumed that depends on both plastic volumetric strain and plastic shear strain.

[0035] The formula corresponding to the size hardening rule is formula (4): (4); where, is the increment of , is the hardening parameter that determines the size of the yield surface, , , , is the residual size hardening parameter, is the initial size hardening parameter, is the specific volume, is the plastic volumetric strain, is the bias softening parameter including the peak plastic shear strain at the beginning of bias softening, is the bias softening parameter including the peak plastic shear strain at the beginning of bias softening, is the initial size hardening parameter, is the compression index, is the rebound index, is the parameter that controls the rate of yield surface softening, is the Heaviside step function, is the shear strain, is the plastic shear strain at which the soft clay starts to show bias softening, is the residual size hardening parameter, , , , is the increment of x to plastic normal strain, is the increment of y to plastic normal strain, is the increment of z to plastic normal strain, for the plastic deviatoric strain vector, for the plastic bulk strain, for xy the plastic deviatoric shear strain, for yz the plastic deviatoric shear strain, for zx the plastic deviatoric shear strain.

[0036] When , When , .

[0037] A second hardening law is introduced to describe the rotation of the yield surface, which is related to the evolution of the soil anisotropy. The same hardening law as in S-CLAY1 is adopted in ADSM, which is derived from the observations of a certain Otaniemi clay. The formula corresponding to the hardening law is given in equation (5):

[0038] (5); where , , , and are constants, and the Macaulay brackets ensure the reasonableness of the model predictions when the soil yields on the dry side of the critical state line , is the absolute value of the plastic deviatoric shear strain.

[0039] As the plastic bulk strain increases, approaches the target value , while as the plastic deviatoric shear strain increases, approaches the target value . controls the absolute rate of approaching the current target value, controls the relative effectiveness of the plastic deviatoric shear strain and the plastic bulk strain in approaching the overall target value of , and the Macaulay brackets ensure the reasonableness of the model predictions when the soil yields on the dry side of the critical state line . Thus when , , and when , .

[0040] S104: Determine the conventional parameters of the third soft clay anisotropic destructuration elastoplastic model, and determine the bias softening parameters of the third soft clay anisotropic destructuration elastoplastic model through triaxial undrained test; the plastic body strain conventional parameters include compression index, resilience index, critical state stress ratio, Poisson's ratio, initial specific volume.

[0041] The parameters required by the ADSM can be determined as follows. The conventional parameters are the same as those of the Modified Cam-clay Model (MCC) model, including compression index , resilience index , critical state stress ratio , Poisson's ratio , and initial specific volume .

[0042] In an exemplary embodiment, the compression index and the resilience index are generated by measuring the unload-load cycle of the isotropic consolidation test.

[0043] The anisotropic parameters of the ADSM include the initial size hardening parameter , the initial rotation hardening parameter , and two constants related to the evolution process of the soil and . and can be determined according to the initial conditions of one-dimensional normal consolidation.

[0044] The calculation formula of the initial rotation hardening parameter is formula (6): (6); is formula (7): (7); wherein , for normal consolidation, the value of the static earth pressure coefficient can be estimated by the Jack formula, , is the critical internal friction angle.

[0045] Substituting into , the critical state stress ratio is formula (8): (8); wherein is the critical state stress ratio, is the critical internal friction angle.

[0046] Another soil constant Estimated by empirical formulas proposed by researchers, The estimated range of values ​​and related, The range of values ​​for is given by formula (9): (9); Parameters related to partial softening in ADSM include: peak plastic shear strain at the onset of partial softening. Residual size hardening parameters and softening rate parameter Suitable for soft clay that is normally consolidated or slightly over-consolidated. , and This was determined through a triaxial undrained test. During the triaxial drained test, the load was continuously increased... Reduce and Increase, therefore The value increases under normal consolidation conditions. Eventually, the critical state line (CSL) is reached. Subsequently, the stress path remains aligned with the CSL line; at this point, according to the yield function... .after The evolution is only affected by plastic deviatoric strain. Therefore, it is assumed that once Upon reaching the CSL (Combined Shear Line), softening begins, and shear bands start to appear. (Ignore) The impact at this time The evolutionary law formula (4) is simplified to formula (10):

[0047] (10); The integral form of formula (10) is derived as formula (11): (11); in, It is an undetermined constant. Under triaxial drainage conditions, before partial softening occurs, Assuming it is constant, and maintaining the initial size hardening parameters. Therefore, and Substitute into equation (11), It was determined to be formula (12):

[0048] (12); Once softening occurs It decreases as it increases. When the softening ends... Residual plastic shear strain ,and Simultaneously attaining the residual size hardening parameter . Therefore, substituting and equation (12) into equation (11), the softening rate parameter is derived as equation (13):

[0049] (13) ; where, , is the actual size hardening parameter when and is the tolerance between

[0050] and The values of and can be measured directly from the results of triaxial undrained tests and the measurements of shear band within triaxial specimens. For triaxial specimens, the vertical total strain and can be measured directly. When is at the maximum, the peak vertical total strain is measured. When reaches the residual value, the residual vertical total strain is measured. When the shear band is fully developed, the thickness of the shear band and the inclination of the shear band (the angle between the vertical line and the shear band) are measured. Therefore, the difference between

[0051] and is calculated as equation (14): where, is the height of the triaxial specimen, and according to the Rankine theory, is approximated as , is the residual vertical total strain, is the peak vertical total strain, and is the thickness of the shear band.

[0052] In practice, the stress condition based on normally consolidated or overconsolidated soils is usually required. In the normally consolidated state, the stress is just on the yield surface. Therefore, the yield condition equation (3) is expressed as equation (15):

[0053] (15) ; where, , and are the mean effective stress, the deviatoric stress vector, and the dimensionless deviatoric fabric vector in the normally consolidated state, respectively.

[0054] Then, The value of is obtained by equation (16) (16); Let y The axis is vertical direction, and can be determined and are formula (17) and formula (18): (17); (18); Wherein, and are Vertical effective stress and horizontal effective stress under normal consolidation condition.

[0055] Therefore, according to formula (17) and formula (18), the value of is calculated as formula (19): (19); Substitute formula (19) into formula (16), the value of can be obtained as formula (20) based on initial state parameters (20); S105: determining the soft clay anisotropic destructuration elastoplastic model based on the plastic body strain conventional parameter, the plastic body strain partial softening parameter and the plastic body strain third soft clay anisotropy destructuration elastoplastic model. In an exemplary embodiment, the present application provides an elastoplastic framework and numerical implementation of ADSM. The elastoplastic framework of ADSM:

[0056] Since the consistency condition requires that the increment of yield function , formula (21) is satisfied:

[0057] (21); Substitute formula (3) into formula (21), formula (22), formula (23) and formula (24) are obtained: (22); (23); (24); Wherein, , , , , .

[0058] ​According to the associated flow rule and the orthogonality assumption, formula (25) is obtained as: (25) where is the plastic multiplier.

[0059] Substituting formula (25) into formula (4) and formula (5), formula (26) and formula (27) are obtained as: (26) (27) where , .

[0060] H is the Heaviside step function, which is the same as formula (4).

[0061] Using the additive decomposition of the total strain increment formula (1), formula (25), formula (26) and formula (27) are substituted into formula (21), and formula (28) is obtained as: (28) where is the elastic stiffness matrix.

[0062] Therefore, Formula (29) is derived from formula (28) as: (29) Substituting formula (29) into formula (1), the effective stress increment calculation is formula (30) as: (30) where , is the elastoplastic stiffness matrix.

[0063] In an exemplary embodiment, the ADSM is numerically implemented in ABAQUS.

[0064] The ADSM model is implemented in the commercial finite element software ABAQUS by using the UMAT and SDVINI subroutines. The forward Euler explicit integration scheme with automatic incremental step is adopted. After one time step , the effective stress at time is first predicted as formula (31) as:

[0065] (31) where is the effective stress predicted by the first time using the forward Euler explicit integration method, and the superscripts and Indicates time. Then in The solution at time t is given by formula (32):

[0066] (32); in, , .

[0067] Is The effective stress at time t is given by formula (33): (33); However, a forward increment step generated by the explicit integration scheme will result in Outside the yield surface. Plastic modification is required to... The stress at any given time is returned to the yield surface, preventing the result from drifting away from the yield surface. A radial regression method is used for plastic correction. Figure 3 This is a schematic diagram of the radial regression method provided by the present invention. Figure 3 The Current yield surface in the text refers to the current yield surface, such as... Figure 3 As shown, this method always performs plastic correction at the center of the yield surface. Assuming the hardening parameters remain constant during the plastic correction process, then... The yield condition at that time is required by formula (34):

[0068] (34); The yield condition is not met, but according to the radial regression method, The solution at time t can be scaled uniformly to satisfy the yield conditions as shown in formulas (35) and (36): (35); (36); in, and For the first prediction of the explicit integration scheme The mean effective pressure and deviatoric stress vector at time t. It is a scaling factor.

[0069] Then, substituting formulas (35) and (36) into the yield condition formula (34), we obtain... For formula (37): (37); use The stress can be updated using formulas (35) and (36), while ensuring that... The yield condition is always met.

[0070] In one exemplary embodiment, the present application provides a method for simulating the behavior of a soil sample in a triaxial test, comprising the steps of: Figure 4 The implementation flowchart of the ADSM model in ABAQUS is shown in FIG. 1, and the flowchart of the implementation of the ADSM model in ABAQUS is shown in FIG. 2. Figure 4 The SDVINI is a user subroutine in ABAQUS, in which the initialization of , , and are performed, the UMART is a user material subroutine in ABAQUS, in which , , , , and are obtained, and and are calculated according to and , when is satisfied, the is obtained, and , , and are calculated, and and are calculated, the Radial return is a radial return algorithm, in which it is judged whether is satisfied, when is satisfied, the is calculated, and the is calculated when is not satisfied. Finally, the is returned.

[0071] In one exemplary embodiment, the present application verifies the performance of the ADSM model.

[0072] The performance of the ADSM is tested by simulating a series of drained triaxial tests on Otaniemi clay. Otaniemi clay is a soft clay whose main mineral components include illite, chlorite and kaolinite. Otaniemi clay has been shown to exhibit significant anisotropy. Undisturbed soil samples for triaxial tests were collected from depths of 3.5-4.7 meters underground.

[0073] Table 1 collects the initial values of the regular parameters of Otaniemi clay required for simulation. These parameters are the same as those used by researchers to simulate Otaniemi clay using the S-CLAY1 model for comparison. It should be noted that the initial values of different samples and are slightly different, although they are the same clay. and The values of are determined based on the normal consolidation state of . The optimal values selected by the researchers in the S-CLAY1 study.

[0074] Based on the undrained test results of the slightly overconsolidated Otaniemi clay specimen CAUC 2238, the related parameters of the partial softening in the ADSM are estimated. The initial anisotropic consolidation stress of the CAUC 2238 specimen is and . The measured maximum deviatoric stress and the residual deviatoric stress are and , respectively. The peak vertical total strain and the residual vertical total strain . The value of can be estimated as . The height of the specimen is 100 mm, but the shear band thickness of the CAUC 2238 sample is not reported. However, the experimental study of the researchers on strain localization shows that the shear band thickness of sensitive clays is between 6.0 ~ 8.0 mm at slow displacement rates. Based on this, the value of is calculated to be 0.48 ~ 0.36 according to Equation (14), where the shear band inclination is estimated using the Rankine theory and . Therefore, a more reasonable value of is used in the subsequent simulations. The initial values of the partial softening parameters in the ADSM are shown in Table 2. Since the value of in CAD2277 is different from that in CAD2251 and CAE2544, the estimated values of and in CAD2277 are also different from the corresponding values in CAD2251 and CAE2544.

[0075] Table 1 Table 2 Each test consists of two loading stages and an unloading stage. The first loading stage is performed at a constant stress ratio until the final stress is reached. The stress ratio is 2-3 times the yield stress observed in this loading stage. The unloading is then performed at the same stress ratio . After the unloading is completed, the second loading is performed at a different constant stress ratio until the final stress is greater than 2-3 times the yield stress at the second loading. The triaxial test program for the three drainage tests is shown in Table 3.

[0076] Table 3 The triaxial tests were simulated using single 8-node linear solid elements (C3D8) in ABAQUS Standard, and the MCC, S-CLAY1 and S-CLAY1S were used for comparison. S-CLAY1 is a degenerated version of ADSM, which does not consider destructuration. MCC is a further degenerated version of S-CLAY1, which cancels anisotropy and rotational hardening. S-CLAY1S is an improved version of S-CLAY1, which considers bonding and partial softening. ADSM, S-CLAY1 and S-CLAY1S have the same initial yield surface when simulated. The initial size of MCC yield surface can be determined when the intersection of MCC yield surface and ADSM yield surface is located on the line (initial soil state is online. . . Figure 5 The initial size of MCC yield surface is determined by the schematic diagram provided by the present application, as shown in Figure 5 . The other parameters required for S-CLAY1S simulation are the same as those selected by the researchers when studying Otaniemi clay (including = 8, = 0.26, = 10 and = 0.2), which are detailed in Koskinen.

[0077] The simulation results of CAD2251 are shown in Figure 6 . CAD2251 includes the first loading stage and the second loading stage . As can be seen from (a) in Figure 6 , MCC, S-CLAY1, S-CLAY1S and ADSM have good prediction effect on the yield stress of the first loading stage, but the yield stress prediction value of MCC is slightly higher than that of S-CLAY1, S-CLAY1S and ADSM. The compressibility can be characterized by the gradient . The compressibility predicted by ADSM and S-CLAY1S in the first loading stage is higher than that predicted by S-CLAY1 and MCC, which is more consistent with the measured results. However, compared with S-CLAY1 and MCC, ADSM and S-CLAY1S can better predict the yield stress in the second loading stage. In the triaxial test, the yield stress prediction value of MCC is the largest difference from the measured value, and the performance is the worst. Figure 6 (b) in . The strain path can be represented by the gradient . From Figure 6As shown in Figure (b), the strain paths predicted by ADSM, S-CLAY1S, and S-CLAY1 are close to the measured values ​​and far superior to those predicted by MCC. However, compared to S-CLAY1S and S-CLAY1, ADSM exhibits lower strain during the unloading-loading cycle. and The predicted values ​​are closer to the measured values. In comparison, MCC performs the worst in strain prediction.

[0078] Figure 7 This is a schematic diagram illustrating the simulation results of the CAE2544 test using MCC, S-CLAY1, S-CLAY1S, and ADSM. The first loading stage of CAE2544 is a stress ratio... The triaxial stretching stage, the second loading stage is The triaxial compression stage. Compared with MCC and S-CLAY1, ADSM and S-CLAY1S predict... - The curves agree well with the measured curves, especially in the first loading stage and the unloading-loading cycle. The yield stresses predicted by ADSM and S-CLAY1S in the first and second loading stages are basically consistent with the measured values. Figure 7 As shown in Figure (b), the strain paths predicted by ADSM, S-CLAY1S, and S-CLAY1 during the first loading stage are similar and close to the strain paths observed in the triaxial test. ADSM and S-CLAY1S predict strain paths during the unloading-loading cycle. and The value is closer to the measured value than the S-CLAY1 prediction. In contrast, the MCC prediction... - The curves differed significantly from the observed results. ADSM and S-CLAY1S showed similar predictive performance for the CAE2544 experiment, but ADSM was significantly better than S-CLAY1 and MCC.

[0079] The simulation results for CAD2277 are as follows: Figure 8 As shown. The stress ratio of CAD2277 in the first loading stage is... Approaching the critical stress ratio The stress ratio in the second loading stage is a constant value. In the first loading stage, all three models predicted the yield stress relatively well. However, in the second loading stage, only the ADSM model predicted a yield stress close to the observed value. Figure 8As shown in Figure (a), S-CLAY1S, S-CLAY1, and MCC all performed poorly in the simulation of the second loading stage, with the yield stress predicted by all three models being underestimated by more than 40%. Triaxial tests indicate that the compressibility of Otaniemi clay differs between the two loading stages, with the stress in the first loading stage being higher than that in the second loading stage. The compressibility is also relatively high. This result demonstrates the influence of plastic deviatoric strain on the compressibility of soft soil. Figure 8 As shown in Figure (b), however, only ADSM and S-CLAY1S accurately captured the different compression ratios in the two loading stages, while S-CLAY1 and MCC predicted similar compression ratios in the two loading stages.

[0080] Similar situations can occur in strain prediction. For example... Figure 8 As shown in Figure (b), the strain path predicted by ADSM is similar to the strain path observed in the triaxial test. ADSM performs well in predicting strain paths during the unloading-loading cycle. and The values ​​are different. In contrast, the strain paths predicted by S-CLAY1S, S-CLAY1, and MCC differ significantly from the observed results. The values ​​predicted by S-CLAY1S, S-CLAY1, and MCC are... The values ​​were underestimated by more than 40%, 50%, and 50%, respectively. S-CLAY1 predicted... The value was underestimated by approximately 30%, while the value predicted by MCC was... It was overestimated by about 50%. The results show that ADSM is better than S-CLAY1S, S-CLAY1 and MCC in predicting the mechanical behavior of soft clay under high stress ratios.

[0081] Based on the CAD2251 experiment, the influence of the partial softening parameter on ADSM prediction results was studied. Figure 9 Showing In the CAD2251 test - and - The influence of the curve. In the parametric study, ADSM used three different values. , and .like Figure 9 As shown in Figure (a), all three cases can predict the yield stress well during the first and second loading stages. However, when the yield stress is reached in the second loading stage, as... As the value increases, the corresponding volumetric strain decreases. This indicates that a higher value is used in ADSM. This value can achieve a lower compression ratio. With... The increase, and The predicted value has decreased significantly. The larger the value, the more it means The slower the rate at which the residual value is reached, the lower the compression ratio. For example... Figure 9 As shown in Figure (b), the predicted strain paths for the three cases are similar in the first and second loading stages, indicating that... The value of has little impact on the strain path.

[0082] Figure 10 Showing right - and - The influence of the predicted curve. Three different values ​​were used in this parameter study. , ,and .like Figure 10 As shown in Figure (a), when When it is a non-zero value ( and It can be observed that the compressibility of the soil reaches an inflection point during the first loading stage. This is because when The value exceeds nonzero. hour, The evolution pattern changes. All three cases can predict the yield stress in the first and second loading stages relatively well. For example... Figure 10 As shown in Figure (b), at the same loading level, with As the value increases, the predicted strain decreases. A higher value indicates that the soil softens later as loading progresses. In all three cases, ADSM predicted similar strain paths, with the strain paths nearly coinciding during the first loading stage, suggesting... The effect on the strain path is minimal.

[0083] The Murro test embankment was built in 1993 at a certain location. The main material of the test embankment was crushed stone, and the construction was completed in two days. Since its completion, researchers have conducted a series of studies on the embankment. Figure 11 This is a schematic diagram illustrating the geometric parameters of the Murro test embankment and the underlying sedimentary soil layer provided by the present invention. The diagram shows the geometry of the Murro test embankment and the sedimentary soil layer beneath it. Figure 11 As shown, the embankment is 2 meters high, 30 meters long, with a slope of 1:2, and the top width of the roadbed is 10 meters.

[0084] The embankment is built on a 23-m-deep deposit of moderately sensitive clay. The deposit can be roughly divided into six layers according to the properties of the clay. The first layer is an overconsolidated dry crust with a thickness of 1.6 m. The second to sixth layers are normally consolidated soft clays. The groundwater level is at 0.8 m below the ground surface. The properties of the layers in the deposit are listed in Table 2. The difference in permeability in the vertical and horizontal directions is considered in the numerical simulation.

[0085] The embankment has been monitored annually or semi-annually since 1993. Figure 12 A schematic diagram of the monitoring instrument layout for the Murro test embankment is provided in the present invention, as shown in Fig. 1. A number of settlement plates (L1-L7) are installed underneath the embankment to monitor the settlement at different locations of the embankment. In addition, an extensometer (E) is installed 2 m away from the centerline of the embankment to monitor the settlement at different depths. Two inclinometers (I1 and I2) are installed at the top and the toe of the embankment to monitor the horizontal displacement at different depths. Eight pore pressure probes (u1-u8) are installed near the center of the embankment to monitor the excess pore pressure at different depths in the deposit. Figure 12

[0086] ABAQUS standard modules are used to perform the plane strain finite element analysis of the construction and consolidation of the Murro test embankment. The embankment is modeled using simple elastic material with material parameters , and , while the deposit is modeled using different elastoplastic constitutive models, including MCC, S-CLAY1, S-CLAY1S and ADSM, for comparison, among which the simulation results of S-CLAY1S can be directly obtained from the research results of the researchers. The finite element mesh of the embankment consists of 108 four-node plane strain elements (CPE4), and the mesh of the clay layer consists of 1073 four-node plane strain pore pressure elements (CPE4P). The pre-conducted mesh sensitivity analysis shows that the mesh of this size is dense enough to obtain accurate results.

[0087] The boundary conditions of the finite element model are shown in Fig. 2. Considering the lateral symmetry of the model, only half of the embankment is modeled. The width of the finite element model is 35 m, which is about 4 times the width of the embankment, to avoid boundary effects. The vertical degrees of freedom of the bottom of the finite element model are fixed, and the horizontal degrees of freedom of the left and right boundaries of the finite element model are fixed. Since the permeability of the glacial till at the bottom of the deposit is much higher than that of the clay, drainage is allowed at the top and bottom boundaries. In ABAQUS, the drainage condition is simulated by setting the pore pressure of the top and bottom boundaries to zero. A suction of -8 kPa is set at the ground surface, and the suction increases linearly with depth until it is zero at the groundwater level. Figure 13

[0088] ​​The basic properties and parameters of the soils under the embankment in the Murro test are collected in Tables 4 and 5. The initial state parameters (including , , and ) are imported into the finite element model through the ABAQUS subroutine SDVINI. The values of at different depths are calculated in SDVINI according to the method in Section 3.3. When calculating the vertical effective stress , the overconsolidation pressure (POP) needs to be considered. Accordingly, the residual size hardening parameter values of the clay layer also vary with the depth. Table 4 lists the properties of the soils under the embankment in the Murro test, and Table 5 lists the parameters of the soils required for the numerical simulation.

[0089] Table 4 Table 5 The finite element simulation is performed in three steps. Step 1 is a “*Static, General” analysis step in the ABAQUS package, which is used to apply the weight of the soil layers and generate the initial geostress. It is noted that the keyword “*Element change, Remove” is used in this analysis step to deactivate the embankment model. The effective self-weight of the clay layer is applied through body forces.

[0090] Steps 2 and 3 are “*Soils, Transient consolidation” analysis steps. Step 2 is used to simulate the construction process of the embankment. In this step, the embankment model is activated using the keyword “*Element change, Add”. The self-weight of the embankment is applied linearly through volume forces in 2 days. Step 3 is used to simulate the consolidation process for 10 years after the construction is completed. Since the construction speed is fast, the nonlinear effects of large deformation are considered in the simulation of the last two steps, and the quasi-Newton solution technique is used to control the iterative balance search.

[0091] The predicted settlement under the centerline of the embankment is compared with the observed settlement over time as shown in Figure 14 . The settlement plates L2, L5, and L7 are arranged along the centerline as shown in Figure 11 . The largest settlement is observed at L7, which is about 0.8 m after 10 years of consolidation, and the smallest settlement is observed at L2, which is about 0.71 m after 10 years of consolidation. The results show that the settlement difference under the centerline of the embankment is about 0.1 m.

[0092] The predicted settlement versus time curves from ADSM and S-CLAY1S agree well with the observed curves at L2. The predicted settlement from S-CLAY1S is slightly larger than that from ADSM. In contrast, the predicted settlements from MCC and S-CLAY1 are much smaller and deviate significantly from the observed settlements at 10 years of consolidation. The predicted settlement from MCC is the smallest, and that from S-CLAY1 is between the predicted settlements from MCC and ADSM. Due to the consideration of partial softening, the predictions of settlements from ADSM and S-CLAY1S are significantly better than those from MCC and S-CLAY1 for the Murro embankment.

[0093] Observed and predicted ground settlements at different times are compared in Figure 15 The settlement plates L1-L7 provide the observed settlements at different times and are compared with the predicted settlement curves along the length of the finite element model. Ground heave is predicted by all models after construction, at 210 days, and at 756 days. Ground heave is most pronounced at about 11 meters from the center of the embankment, near the toe of the embankment. Ground heave gradually disappears after 756 days of consolidation, and settlement increases with time. ADSM performs well in predicting ground settlements, especially at 1966 days and 3052 days. In contrast, both MCC and S-CLAY1 underestimate ground settlements. Among the three models, the MCC model performs the worst because its predictions deviate the most from the observed settlements.

[0094] Observed and predicted horizontal displacements versus depth below the crest and toe of the embankment are shown in Figure 16 The observed horizontal displacements from inclinometer I1 are at the soil layer below the crest of the embankment, and those from inclinometer I2 are at different depths below the toe of the embankment. As shown in Figure 16 (a) of ADSM, S-CLAY1S, and S-CLAY1 perform well in predicting the horizontal displacements within 5 m depth below the crest of the embankment after construction. MCC underestimates the horizontal displacements within 5 m depth. All models overestimate the horizontal displacements below the crest of the embankment at depths greater than 5 m.

[0095] After 8 years of consolidation, as shown in Figure 16 (b) of ADSM's predictions are closest to the observations, about 0.10 m, while S-CLAY1 and MCC underestimate the horizontal displacements, and S-CLAY1S significantly overestimates the horizontal displacements. As shown in Figure 16 (c) of All four models overestimate the horizontal displacements at the toe of the embankment after construction. After 8 years of consolidation, as shown in Figure 16As shown in Figure (d), the four models predicted the maximum horizontal displacement at a depth of approximately 2 m, while the observed maximum value was approximately 5 m. However, ADSM predicted the maximum horizontal displacement at the toe of the embankment most accurately after 8 years of consolidation, at approximately 0.12 m. MCC and S-CLAY1 both underestimated the magnitude of the maximum horizontal displacement, while S-CLAY1S overestimated it.

[0096] The settlement at different depths below the center of the embankment changes over time as follows: Figure 17 As shown. Figure 17 Figure (a) shows a comparison between observed and predicted settlement measured by the extensometer (E). At depths near the surface (Z=1m), the settlement predictions of ADSM and S-CLAY1S are closest to the measured values. In contrast, the MCC model predicts the lowest settlement, while the S-CLAY1 model predicts settlement values ​​between those of ADSM and MCC models.

[0097] As depth increases, such as Figure 17 Figure (c) in the middle and Figure 17 As shown in Figure (d), the settlement predictions of S-CLAY1 and MCC gradually approach those of ADSM and S-CLAY1S. At depths of 4.4 m and 6.4 m, ADSM, S-CLAY1S, and S-CLAY1 give almost identical settlement predictions, all underestimating the settlement values. However, within 6.4 m below the embankment, the MCC model underestimates the settlement after 10 years of consolidation by more than 30%. Overall, ADSM and S-CLAY1S exhibit similar performance in the Murro test embankment consolidation simulation, and outperform S-CLAY1 and MCC.

[0098] To demonstrate the effect of softening The influence of surface evolution in ADSM and S-CLAY1 simulations The change in value is as follows Figure 18 As shown. After construction is completed, The pressure decreases slightly at the toe of the embankment, to approximately 11.6 kPa, while it decreases in other parts of the surface. Maintain the initial value of 12.7 kPa. As time increases, at the center of the embankment... The value increases. After 219 days of consolidation, the ADSM-predicted embankment center... The value reached 18.7 kPa and has remained unchanged thereafter.

[0099] In contrast, S-CLAY1's prediction at the center of the embankment... The value continues to increase over time, eventually reaching its predicted value after 10 years of consolidation. The deviation from the initial value and the deviation from the ADSM prediction value showed a relative difference of approximately 12%. However, during the 10-year consolidation process, the toe of the embankment... The values ​​first decreased and then increased. At the toe of the embankment, ADSM and S-CLAY1 predicted... The values ​​all reached their lowest values ​​after 219 days of consolidation. After 10 years of consolidation, The value reached a maximum of 21.4 kPa. After 10 years of consolidation, The minimum value moves from the embankment to a position between the embankment toe and the embankment crest. Overall, the consolidation effect on the compressibility of soft soil is mainly concentrated below the embankment, with less impact on other parts of the surface.

[0100] Figure 19 Anisotropic parameters at different times in ADSM and S-CLAY1 simulations Distribution at the surface is used to demonstrate the effect of softening on value evolution. Near the embankment toe. The change was most pronounced at the toe of the embankment, while at other locations it remained close to its initial value. After the embankment construction was completed, the value first increased at the toe of the embankment. After 219 days of consolidation, the ADSM predicted value reached its maximum value of approximately 0.72 at a distance of 10 m from the center of the embankment.

[0101] Subsequently, ADSM predicted The value reached its minimum at 1131 days, at approximately 0.49. However, after 10 years of consolidation, The predicted value rose to 0.58. At 1131 days and 3066 days, S-CLAY1 predicted... The values ​​were significantly lower than those predicted by ADSM. After 1131 days and 10 years of consolidation, the values ​​predicted by both models were... The relative differences between the initial values ​​and the actual values ​​reached 19% and 83%, respectively. It can be found that, unlike the evolution process of compressibility, the growth and elimination of anisotropy in soft soil under consolidation only occur in a narrow area near the toe of the embankment.

[0102] like Figure 20 As shown, sedimentary soil layers The cloud map shows that the anisotropy of soft clay mainly occurs in the near-surface soil layer. In a certain area below the embankment, especially near the embankment toe, after construction is completed ( Figure 20 (Figure (a) in the middle) and after 219 days of consolidation ( Figure 20 After (b) in the middle, The value increases significantly. As consolidation progresses, a clear... "Bubble" gradually formed below the embankment toe. Figure 20 Figure (c) in the middle and Figure 20 (Figure d)). As bubbles form, the contents of the bubbles... The value decreases significantly. The consolidation process has a smaller impact on the anisotropy of soft soils in deeper soil layers or far from the embankment. Convex maps show that the soft clay in these areas... The value remains basically constant, similar to the initial value. =0.64 is close.

[0103] When applying the anisotropic unstructured elastoplastic model method for soft clay provided by this invention, it is not necessary to consider... Figure 1 The steps shown are executed in sequence. The specific execution order of each step can be determined as needed, and this invention does not impose any restrictions on it.

[0104] The above describes a method for constructing an anisotropic destructured model of soft clay containing softened material, provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for constructing an anisotropic destructured elastoplastic model of soft clay, such as... Figure 21 As shown.

[0105] Figure 21 A schematic diagram of an anisotropic destructured elastoplastic modeling device for soft clay provided by the present invention includes: The first building module 2101 is used to use the anisotropic elastoplastic constitutive model S-CLAY1 as the first anisotropic destructured elastoplastic model of soft clay.

[0106] The second construction module 2102 is used to construct a calculation formula for the effective stress increment based on the additive decomposition principle of the total strain increment, and to introduce the calculation formula for the effective stress increment into the first soft clay anisotropic destructured elastoplastic model to obtain the second soft clay anisotropic destructured elastoplastic model; the calculation formula for the effective stress increment is used to describe the elastic behavior of the first soft clay anisotropic destructured elastoplastic model.

[0107] The third building module 2103 is used to introduce size hardening laws into the second anisotropic destructured elastoplastic model of soft clay to obtain the third anisotropic destructured elastoplastic model of soft clay. The size hardening law of plastic body strain is constructed based on the hardening parameters that determine the yield surface size, which depend on both plastic body strain and plastic shear strain. The size hardening law includes a partial softening parameter. The partial softening parameter of plastic body strain includes the peak plastic shear strain at the beginning of partial softening, the size hardening parameter, and the softening rate parameter.

[0108] The first determining module 2104 is used to determine the conventional parameters of the anisotropic unstructured elastoplastic model of the third soft clay, and to determine the softening parameters of the anisotropic unstructured elastoplastic model of the third soft clay through triaxial undrained tests; the conventional parameters of plastic body strain include compression index, springback index, critical stress ratio, Poisson's ratio, and initial specific volume.

[0109] The second determining module 2105 is configured to determine the anisotropic destructured elastoplastic model of soft clay based on the plastic body strain conventional parameter, the plastic body strain softening parameter and the plastic body strain third soft clay anisotropic destructured elastoplastic model.

[0110] The specific limitation of the construction device of the anisotropic destructured elastoplastic model of soft clay can refer to the limitation of the construction method of the anisotropic destructured elastoplastic model of soft clay in the above, which will not be repeated here. Each module in the construction device of the anisotropic destructured elastoplastic model of soft clay can be realized by software, hardware and a combination thereof. The above-mentioned each module can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so as to call and execute the operation corresponding to each module by the processor.

[0111] The application further provides a computer readable storage medium, which stores a computer program, and the computer program can be used to execute the above-mentioned Figure 1 The construction method of the anisotropic destructured elastoplastic model of soft clay is provided.

[0112] The application further provides a computer readable storage medium, which stores a computer program, and the computer program can be used to execute the above-mentioned Figure 22 The structure diagram of the computer device is shown in the figure, and the computer device includes a processor, an internal bus, a network interface, a memory and a non-volatile memory. Figure 22 As shown in the figure, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory and a non-volatile memory, and of course can also include other hardware required by business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs to realize the above-mentioned Figure 1 The construction method of the anisotropic destructured elastoplastic model of soft clay is provided.

[0113] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments of the methods. In the embodiments of the present application, any reference to memory, storage, database or other medium can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0114] The technical features of the above embodiments can be combined in any way. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

Claims

1. A method for constructing an anisotropic unstructured elastoplastic model of soft clay, characterized in that, include: The anisotropic elastoplastic constitutive model S-CLAY1 was used as the first anisotropic destructured elastoplastic model for soft clay. Based on the additive decomposition principle of total strain increment, a calculation formula for effective stress increment is constructed. This formula is then introduced into the first anisotropic unstructured elastoplastic model of soft clay to obtain the second anisotropic unstructured elastoplastic model of soft clay. The calculation formula for effective stress increment is used to describe the elastic behavior of the first anisotropic unstructured elastoplastic model of soft clay. A size hardening law is introduced into the second anisotropic destructured elastoplastic model of soft clay to obtain a third anisotropic destructured elastoplastic model of soft clay. The size hardening law is constructed based on the hardening parameters that determine the yield surface size, which depend on both plastic strain and plastic shear strain. The size hardening law includes a partial softening parameter, which includes the peak plastic shear strain at the beginning of partial softening, the size hardening parameter, and the softening rate parameter. The conventional parameters of the anisotropic unstructured elastoplastic model of the third soft clay were determined, and the softening parameters of the anisotropic unstructured elastoplastic model of the third soft clay were determined by triaxial undrained tests. The conventional parameters include the compression index, the resilience index, the critical stress ratio, Poisson's ratio, and the initial specific volume. Based on the conventional parameters, the softening parameters, and the third anisotropic destructured elastoplastic model of soft clay, the anisotropic destructured elastoplastic model of soft clay is determined.

2. The method as described in claim 1, characterized in that, The formula for calculating the effective stress increment is: ； in, For the effective stress increment, For the effective stress vector, , for x Towards effective normal stress, for y Towards effective normal stress, for z Towards effective normal stress, for xy Towards shear stress, for yz Towards shear stress, for zx Towards shear stress, The total stress vector, , for x To adapt to change, for y To adapt to change, for z To adapt to change, for xy Shear strain, for yz Shear strain, for zx Shear strain, The plastic strain vector , for x Towards plastic normal strain, for y Towards plastic normal strain, for z Towards plastic normal strain, for xy Towards plastic shear strain, for yz Towards plastic shear strain, for zx Towards plastic shear strain, Here is the elastic stiffness matrix; The elastic stiffness matrix is: ； in, Here is the elastic stiffness matrix. Shear modulus Let Lamé constant be . , , , Poisson's ratio, For average effective pressure, For specific volume, The rebound index, It is the elastic bulk modulus.

3. The method as described in claim 1, characterized in that, The formula corresponding to the dimension hardening law is: ； in, for The increment, To determine the hardening parameters for the yield surface size, , , For residual size hardening parameters, These are the initial size hardening parameters. For specific volume, For plastic strain, The softening parameters include the peak plastic shear strain at the onset of softening. The softening parameters include the peak plastic shear strain at the onset of softening. These are the initial size hardening parameters. The compression index is... The rebound index, Parameters for controlling the softening rate of the yield surface, For Heaviside step function, For shear strain, This represents the plastic shear strain at which soft clay begins to soften. For residual dimensional hardening parameters, , , , for x Towards plastic normal strain, for y Towards plastic normal strain, for z Towards plastic normal strain, For the plastic deviatoric strain vector, For plastic strain, for xy Towards plastic shear strain, for yz Towards plastic shear strain, for zx Towards plastic shear strain.

4. The method as described in claim 1, characterized in that, Both the compression index and the springback index are generated by unloading-loading cycle measurement in an isotropic consolidation test. The formula for calculating the critical stress ratio is: ； in, The critical stress ratio. This is the critical internal friction angle.

5. The method as described in claim 1, characterized in that, The peak plastic shear strain at the onset of softening The results were obtained from the triaxial undrained test and the measurement of the shear band within the triaxial specimen. The formula for calculating the softening rate parameter is as follows: ； in, For softening rate parameters, The softening parameters include the peak plastic shear strain at the onset of softening. This represents the residual plastic shear strain. For when The tolerance between the actual dimensional hardening parameters and the residual dimensional hardening parameters at that time. For shear strain, For residual size hardening parameters, These are the initial size hardening parameters.

6. The method as described in claim 1, characterized in that, The anisotropic destructured elastoplastic model of soft clay further includes a yield function and a plastic potential function; the formulas corresponding to the yield function and the plastic potential function are as follows: ； in, Let be the yield function. Let be the plastic potential function. , , , To determine the hardening parameters for the yield surface size, The critical stress ratio. Geometrically, it is the stress ratio line. The average effective stress at the intersection with the yield surface, To control the hardening parameters of the yield surface inclination angle, The components satisfy the relation , for x Towards effective normal stress, for y Towards effective normal stress, for z Towards effective normal stress, for xy Towards shear stress, for yz Towards shear stress, for zx Towards shear stress, A dimensionless partial construction vector x To the component, A dimensionless partial construction vector y To the component, A dimensionless partial construction vector z To the component, A dimensionless partial construction vector xy To the component, A dimensionless partial construction vector yz To the component, A dimensionless partial construction vector zx Towards the component.

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