A flexible triaxial discrete element model construction method, system and medium
By creating a flexible granular membrane in the EDEM platform and combining it with secondary development technology, the problem of inaccurate confining pressure application in flexible triaxial modeling was solved, improving computational efficiency and simulation accuracy. This method is suitable for simulating the shear mechanical behavior of silty clay.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF MECHANICS CHINESE ACAD OF SCI
- Filing Date
- 2025-08-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing flexible triaxial numerical simulation experiments involve complex modeling processes, performance bottlenecks when simulating a large number of particles, and the EDEM platform cannot accurately apply confining pressure, resulting in large errors in the simulation results.
By importing the geometric information of rubber mold particles into the EDEM platform, a flexible granular membrane is created using Python code. Combined with the RigidLink function of the granulation plant, it is rigidly connected to the axially loaded piston block. The triaxial consolidation and shearing process under confining pressure conditions is simulated using a secondary developed .dll dynamic link library file.
It achieves precise application of confining pressure, improves computational efficiency, ensures the accuracy and stability of simulation results, and can efficiently simulate the shear mechanical behavior of silty clay.
Smart Images
Figure CN120995815B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soil mechanical behavior. In particular, it relates to a method, system, and medium for constructing a flexible triaxial discrete element model. Background Technology
[0002] The Discrete Element Method (DEM) was first introduced into the field of rock mechanics research by American scholar Cundall in 1971. It has been widely used to study the mechanical behavior of complex discrete particle systems such as soil and powder. In the study of soil mechanical behavior, DEM mainly involves the simulation of typical scenarios such as triaxial experiments, shear experiments and static cone penetration tests.
[0003] In traditional indoor triaxial experiments, wrapping soil samples with a flexible rubber mold is a common practice. Early flexible membrane technologies used in DME triaxial numerical simulation experiments attempted to define the outermost particles of the soil sample as membrane particles. However, this method easily leads to the migration of membrane particles and inner soil particles during triaxial shearing, requiring repeated identification of membrane particles in numerical calculations, reducing computational efficiency, and making it difficult to accurately simulate the real mechanical behavior of the rubber membrane. Subsequent research proposed an innovative scheme to generate adhesive bonds between membrane particles. By simulating the elastic constraint characteristics of the rubber membrane, the migration of outer membrane particles and inner soil particles is effectively avoided. Simultaneously, to prevent soil particles from escaping during large deformation shearing, membrane particles are often arranged in a hexagonal, tightly packed pattern to enhance the constraint effect. Furthermore, some researchers have explored coupling techniques between DEM and FDM (Finite Difference Method) and FEM (Finite Element Method), using software platforms such as PFC-FLAC3D to achieve precise construction of flexible membranes. However, all of the above techniques have their own drawbacks. In flexible triaxial numerical experiments based on particulate membranes, the increase in the number of membrane particles leads to an exponential increase in the computational cost of bonding, severely limiting the expansion of model scale. Furthermore, current particulate membrane technologies largely rely on commercial PFC software, which only supports CPU multi-threaded parallel computing. As simulation complexity increases, its simulation performance bottleneck becomes increasingly apparent, making it difficult to meet the demands of large-scale, high-resolution numerical simulations. In the coupling technique approach, data transfer between different numerical methods faces challenges in matching spatiotemporal scales: for example, force-displacement conversion errors between FEM elements and DEM particles can easily lead to distorted simulation results. Moreover, the construction process of triaxial simulation models based on coupling techniques is more complex, further limiting the widespread adoption and application of this type of method.
[0004] The EDEM platform boasts significant application advantages thanks to its intuitive and user-friendly interface. However, the native interface of the EDEM platform software cannot directly apply confining pressure to cylindrical specimens. Typically, a square specimen of similar size is generated, and then a true triaxial stress state is applied to approximate the triaxial test of the cylindrical specimen in the laboratory. Specifically, this is achieved by precisely controlling the triaxial stress state of the DEM true triaxial model (…). ), and set standard dimensions (39.1mm×39.1mm×80mm) to equivalently simulate the triaxial stress state of a conventional triaxial test in the experiment ( The sample geometry (φ19.55mm × 80mm) is shown in Figure 1. Figure 1 (a) is the indoor triaxial experimental diagram, (b) is the force diagram of my true triaxial simulation of EDEM, and (c) is the geometric dimension diagram. Since this processing method has differences in boundary conditions compared with the experiment, errors will inevitably occur.
[0005] In summary, DEM triaxial simulation experiments based on EDEM software still have enormous room for technological innovation and optimization in the field of discrete element numerical simulation, and urgently need to be improved or further developed to achieve more accurate and efficient simulation results. Summary of the Invention
[0006] This invention provides a method, system, and medium for constructing a flexible triaxial discrete element model, in order to solve the performance bottlenecks that exist when the modeling process is complex and the number of simulation particles is large in flexible triaxial numerical simulation experiments.
[0007] To achieve the above objectives, in a first aspect, the present invention relates to a method for constructing a flexible triaxial discrete element model for modeling flexible triaxial numerical simulation experiments of EDEM, comprising:
[0008] The microscopic contact parameters of silty clay and rubber mold are obtained through calibration experiments or literature. Silty clay material and rubber mold material are created in EDEM, and the microscopic contact parameters of the silty clay material and the rubber mold material are set.
[0009] Based on the EDEM element particle function, the geometric information of rubber mold particles is imported from the outside using Python code to create a flexible particle film, wherein the geometric information includes at least spatial coordinates and physical radius;
[0010] A geometric boundary model of the flexible granular membrane with the same size as the indoor triaxial instrument is constructed. The generated geometric boundary model is positioned in virtual space corresponding to the position of the real experimental device by using the spatial coordinate adjustment function, thus completing the positioning of the flexible granular membrane.
[0011] The flexible granular membrane is generated using the static generation method of the granulation plant. Based on the RigidLink function of the granulation plant, the flexible granular membrane is rigidly connected to the axially loaded piston block. After the flexible granular membrane is formed, the volume filling function of the granulation plant is called to generate a set of silty clay sample particles with specified gradation characteristics.
[0012] Import a .dll dynamic link library file based on secondary development into the particle contact model and the particle volume force calculation model of the EDEM to realize the simulation of triaxial consolidation and shear process under preset confining pressure conditions.
[0013] To achieve the above objectives, in a second aspect, the present invention relates to a flexible triaxial discrete element model construction system for modeling and simulating flexible triaxial numerical simulation experiments of EDEM, comprising:
[0014] The material creation and parameter setting module is used to obtain the microscopic contact parameters of silty clay and rubber mold through calibration experiments or literature, create silty clay material and rubber mold material in EDEM, and set the microscopic contact parameters of the silty clay material and the rubber mold material.
[0015] The flexible particle mold creation module is used to create a flexible particle film by importing the geometric information of rubber mold particles from an external source using Python code based on the EDEM element particle function. The geometric information includes at least spatial coordinates and physical radius.
[0016] The geometric model generation module is used to construct a geometric boundary model of the flexible granular membrane with the same size as the indoor triaxial instrument. The generated geometric boundary model is positioned in the virtual space corresponding to the position of the real experimental device through the spatial coordinate adjustment function, thereby completing the positioning of the flexible granular membrane.
[0017] The sample generation module is used to generate the flexible granular membrane using the static generation method of the particle factory. Based on the Rigid Link function of the particle factory, the flexible granular membrane is rigidly connected to the axially loaded piston block. After the flexible granular membrane is formed, the volume filling function of the particle factory is called to generate a set of silty clay sample particles with specified gradation characteristics.
[0018] The secondary development simulation module is used to import .dll dynamic link library files based on secondary development into the particle contact model and particle volume force calculation model of the EDEM, so as to realize the simulation of triaxial consolidation and shear process under preset confining pressure conditions.
[0019] To achieve the above objectives, in a third aspect, the present invention also relates to a computer-readable storage medium storing instructions that, when executed, perform the above-described method for constructing a flexible triaxial discrete element model.
[0020] The present invention relates to a flexible triaxial discrete element model construction method, system, and medium, which has the following advantages compared with the prior art:
[0021] It provides a secondary development interface, enabling precise application of confining pressure. This solves the challenges of flexible triaxial modeling and simulation and precise application of confining pressure on the EDEM platform, and significantly improves the computational efficiency of flexible triaxial simulation.
[0022] In the geometric model parameter setting stage, not only were parameters assigned to each component consistent with actual material properties, but the contact parameters between the components and soil particles and the rubber membrane were also meticulously defined to realistically simulate the interactions between materials. To ensure the stability of the rubber membrane particle generation process, a boundary wall structure was added to the outermost layer of the model. This boundary wall effectively guides the stress release during the initial generation of the rubber membrane particles, preventing the particles from collapsing due to uneven initial stress and ensuring the reliability of the simulation model. The creation and assembly of the flexible membrane and silty clay sample were successfully completed, resulting in a triaxial model that ensures both accuracy in simulating mechanical behavior and high modeling efficiency.
[0023] Based on the flexible triaxial technology proposed in this invention, a simulated indoor triaxial test was conducted on silty clay, which is widely used in engineering construction. This method can effectively simulate the shear mechanical behavior of silty clay in indoor triaxial experiments. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of an indoor triaxial experiment simulated using EDEM software in the existing technology.
[0025] Figure 2 This is a flowchart illustrating a method for constructing a flexible triaxial discrete element model in Example 1.
[0026] Figure 3 This is a flowchart illustrating the construction and secondary development process of a flexible triaxial discrete element model based on a granular membrane structure, as described in Example 1 of the flexible triaxial discrete element model construction method in Embodiment 1.
[0027] Figure 4 This is a schematic diagram of the granular structure of the flexible membrane in the flexible triaxial discrete element model construction method of Example 1.
[0028] Figure 5 This is a schematic diagram of the imported geometric model for a flexible triaxial discrete element model construction method in Example 1.
[0029] Figure 6This is a schematic diagram of the generation of a flexible membrane, the generation of a silty clay sample, and the corresponding DEM triaxial numerical model in Example 1, which is a method for constructing a flexible triaxial discrete element model.
[0030] Figure 7 This is a schematic diagram of the secondary development technology path of the confining pressure loading module in the DEM triaxial numerical simulation of a flexible triaxial discrete element model construction method in Example 1.
[0031] Figure 8 This is a flowchart of the isotropic consolidation operation in the DEM triaxial numerical simulation of a flexible triaxial discrete element model construction method in Example 1.
[0032] Figure 9 This is a flowchart of the shearing operation in the DEM triaxial numerical simulation of Example 1 of the flexible triaxial discrete element model construction method in Embodiment 1.
[0033] Figure 10 This study compares the indoor triaxial test results of Example 1 of the flexible triaxial discrete element model construction method in Embodiment 1 with the shear mechanical behavior of the flexible triaxial test results of the present invention.
[0034] Figure 11 This is a flowchart illustrating the simulation of a flexible triaxial discrete element model based on a granular membrane structure, as described in Example 1 of the flexible triaxial discrete element model construction method in Embodiment 1.
[0035] Figure 12 This is a schematic diagram of a flexible triaxial discrete element model construction system in Example 2. Detailed Implementation
[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention and not the entire structure.
[0037] Example 1
[0038] A method for constructing a flexible triaxial discrete element model; please refer to [link / reference]. Figure 2-11 As shown, this invention provides a method for constructing a flexible triaxial discrete element model, used for modeling flexible triaxial numerical simulation experiments of EDEM, such as... Figure 2-3 As shown, the procedure includes the following steps: S101 to S105.
[0039] S101 obtains the microscopic contact parameters of silty clay and rubber mold through calibration experiments or literature. Then, it creates silty clay material and rubber mold material in EDEM and sets the microscopic contact parameters of the silty clay material and the rubber mold material.
[0040] In this embodiment, taking a conventional indoor triaxial experiment (sample size φ19.55mm×80mm) as an example, discontinuous graded silty clay (density 1.4g / cm³, moisture content 0%) under a confining pressure of 100kPa is used to create silty clay material and rubber mold material in EDEM. Specifically, the parameters for creating the silty clay material include at least Poisson's ratio, true density, and shear modulus (which can be determined based on the experimental results of the granular material properties). The parameters for creating the rubber mold material include at least normal stiffness per unit area, tangential stiffness per unit area, critical normal strength, and critical tangential strength. These parameters need to be determined through targeted calibration. The contact model of the rubber mold material needs to call the Bonding V2 model. The Bonding V2 model binds particles together with finite-sized "glue" bonds. These bonds resist tangential and normal motion until the maximum normal and tangential shear stresses are reached, at which point the bonds break, and the particles will interact like hard spheres. This model can be used for modeling flexible particles such as fibers / straw.
[0041] The microscopic contact parameters of silty clay materials and rubber mold materials should include at least the coefficient of restitution, the static friction coefficient, and the rolling friction coefficient (which need to be obtained through calibration experiments).
[0042] Setting the microscopic contact parameters for silty clay materials and rubber mold materials also includes:
[0043] The process involves adding particles and setting parameters for both silty clay and rubber mold materials. This includes defining the initial physical radius, contact radius, and particle size distribution of the particles. For discontinuously graded silty clay particles, the percentage content of each particle size is set based on particle size scaling and particle size distribution experimental results. Alternatively, the particle size distribution data from an Excel spreadsheet can be imported using the "Import" function to achieve precise matching with the actual particle size distribution characteristics of the material. The physical diameter of the rubber mold particles is set by converting the actual thickness of the indoor rubber mold into an equivalent particle diameter. Based on calibration experiments, the contact diameter of the rubber mold particles is set as a multiple of the physical radius.
[0044] The particle size scaling is as follows: First, based on the sampled silty clay, the actual particle size distribution is obtained using a particle size analyzer. If simulation is performed according to the actual particle size distribution, the required number of particles would be in the tens of millions (hundreds of millions), which is beyond the capabilities of current computer performance. Therefore, in conjunction with relevant literature, such as MacDonald's (2012) particle refinement method, the particle size is scaled up proportionally by about 20 to 50 times based on the original particle size distribution. This results in a simulation accuracy that is acceptable to researchers. This invention employs a 20-fold particle size scaling, and its computational efficiency is also acceptable for current ordinary workstations.
[0045] Based on specific calibration experiments, the contact diameter in this embodiment can be set to 1.5 times the physical radius. The source of this multiple of the physical radius is mainly based on the range given by EDEM, approximately 120% to 150%; the specific value needs to be determined according to the physical properties of the rubber membrane used in the experiment. A larger contact radius will make the simulated flexible membrane exhibit more flexible mechanical behavior. The contact radius and microscopic parameters are determined based on actual rubber membrane stretching and shearing experiments.
[0046] S102 uses the EDEM meta-particle function to import the geometric information of rubber mold particles from the outside using Python code to create a flexible granular membrane. The geometric information includes at least spatial coordinates and physical radius.
[0047] Specifically, the spatial coordinates of the rubber membrane particles, obtained from indoor triaxial experiments, are generated using Python code. The spatial coordinates of these particles are then imported into the EDEM (Electronic Derivative Module) using the Meta-Particle function. This creates a flexible membrane with the rubber membrane particles as the basic particle unit. The flexible particle membrane of this invention is entirely composed of spherical particles, with no irregularly shaped particles. The particles are arranged in a hexagonal pattern. No adhesive bonds are currently formed between the constituent particles of this flexible membrane. To prevent the escape of soil particles during triaxial consolidation and shearing processes, the flexible membrane particles are arranged in a hexagonal pattern. For example, with a rubber membrane thickness of 1 mm, a total of 14375 basic particles are generated. Figure 4 As shown.
[0048] S103 constructs a geometric boundary model of a flexible granular membrane of the same size as the indoor triaxial instrument. By adjusting the spatial coordinates, the generated geometric boundary model is positioned in virtual space to correspond to the position of the real experimental device, thus completing the positioning of the flexible granular membrane.
[0049] S104 uses the static generation method of the particle factory to generate a flexible particle membrane. Based on the RigidLink function of the particle factory, the flexible particle membrane is rigidly connected to the axially loaded piston block. After the flexible particle membrane is formed, the volume filling function of the particle factory is called to generate a set of silty clay sample particles with specified gradation characteristics.
[0050] Specifically, when constructing the triaxial experimental model in the EDEM simulation environment, the required geometric model is accurately imported into the system using the Add Geometry function of the Creator Tree module. Before importing, the length unit is uniformly set to mm to ensure that the model size strictly corresponds to the actual indoor triaxial experiment. Subsequently, the generated geometric model is precisely positioned using the spatial coordinate adjustment function, so that its layout in virtual space highly matches the real experimental setup.
[0051] In the geometric model parameter setting stage, not only were parameters assigned to each component that conformed to the actual material properties, but the contact parameters between them and the soil particles and rubber membrane were also meticulously defined to realistically simulate the interaction between materials. To ensure the stability of the rubber membrane particle generation process, a boundary wall structure was added to the outermost layer of the model. This boundary wall can effectively guide the stress release during the initial generation of the rubber membrane particles, preventing the particles from collapsing due to uneven initial stress and ensuring the reliability of the simulation model. The model architecture after completing the above operations is shown in Figure 5.
[0052] When constructing a triaxial model using EDEM, considering that the flexible membrane particle structure had already been created in step S102, a static generation method using a particle factory was adopted for both the flexible membrane and the silty clay sample to ensure modeling efficiency and structural stability. For the flexible membrane, the Rigid Link function of the particle factory was enabled, and it was rigidly connected to the axially loaded piston block. This fixed constraint mechanism ensures that the flexible membrane moves synchronously with the piston block during the test loading process, avoiding simulation errors caused by relative displacement. The generation of the silty clay sample was based on pre-designed key physical parameters such as density and particle size. To simplify the operation process, a static generation mode of volume packing was selected. This method can quickly fill particles in a specified space based on set parameters, accurately restoring the physical properties of the silty clay sample, such as... Figure 6 The diagrams are shown as follows: (a) the formation of the flexible membrane, (b) the formation of the silty clay sample, and (c) the triaxial numerical model of the DEM.
[0053] S105 imports a .dll dynamic link library file based on secondary development into the particle contact model and particle volume force calculation model of EDEM to realize the simulation of triaxial consolidation and shear processes under preset confining pressure conditions.
[0054] In this embodiment, before S105 and after S104, the following is also included:
[0055] Based on the secondary development interface of EDEM, a custom library CM_UDL for particle contact model based on EDEM and a user-defined library PBF_UDL for particle volume force based on EDEM are generated as dynamic link library .dll files. Among them, CM_UDL stores the contact pairs and particle coordinate information of particles in the flexible membrane, so as to provide PBF_UDL to obtain particle information. PBF_UDL mainly implements the application of particle force in the flexible particle membrane under a preset confining pressure.
[0056] Among them, BF_UDL mainly implements the application of particle force to the flexible particulate membrane under a preset confining pressure, so as to provide PBF_UDL with particle information; the specific development process is as follows: Figure 7 As shown; the API for applying triaxial confining pressure in this invention is mainly compiled based on Microsoft's Visual Studio 2022 tool.
[0057] In this embodiment, the formula for applying particle force in the flexible particulate membrane is: ;
[0058] In the formula: It is represented as the radial force vector acting on a single particle in a flexible particulate membrane; Represents the magnitude of the confining pressure; The cross-sectional area representing a spherical particle: Represents the radius of the particle; Represents the direction of radial force (unit vector).
[0059] In this embodiment, S105 includes:
[0060] Import the .dll file into the particle contact model and particle volume force calculation model of EDEM respectively, set the force magnitude of the upper axial loading plate to achieve triaxial isotropic consolidation operation; import the .dll file into the particle contact model and particle volume force calculation model of EDEM respectively, switch the force control mode of the upper axial loading plate to constant speed loading, and simulate the shear process by setting the axial displacement rate to induce axial deformation of the silty clay sample under the preset confining pressure.
[0061] In this embodiment, isotropic consolidation is an indispensable fundamental step in the triaxial test, the core purpose of which is to uniformly apply confining pressure ( This allows the specimen to reach an initial stress equilibrium state, providing standardized initial conditions for subsequent shear tests. Therefore, after step (4) is completed, the .dll file is imported into the EDEM contact model module and the particle volume force module respectively, and the force magnitude of the upper axial loading plate (geometry upper-L) is set to achieve triaxial isotropic consolidation, such as... Figure 8 As shown. In the triaxial numerical simulation of DEM, the shearing operation process is similar to that of isotropic consolidation, both achieving loading by setting boundary conditions. However, the core difference lies in the change of the loading control mode. In the shearing stage, the force control mode of the upper axial loading plate is switched to constant velocity loading, that is, by setting the axial displacement rate (e.g., v = 0.03 mm / s), the sample is subjected to a fixed confining pressure ( Axial deformation is generated while maintaining the same temperature (i.e., the temperature remains constant) to simulate the shear failure behavior of silty clay. The specific operation procedure is as follows: Figure 9 As shown.
[0062] To better illustrate the solution of the present invention, an example is given below, such as... Figure 10 As shown, Figure 10 (a) is an indoor triaxial experimental diagram, (b) is a flexible triaxial numerical simulation diagram established by this invention, and (c) is a comparative analysis diagram of stress-strain curves during shearing, including the following steps:
[0063] Taking a conventional indoor triaxial test (sample size φ19.55mm×80mm) of discontinuous graded silty clay (density 1.4g / cm³, moisture content 0%) under a confining pressure of 100kPa as an example, the specific implementation procedure is as follows:
[0064] Based on the flexible triaxial technology proposed in this invention, a simulated indoor triaxial test was conducted on silty clay, which is widely used in engineering construction. The test used standard specimen sizes (19.55 mm in diameter and 80 mm in height) and simulated the shear mechanical behavior of silty clay specimens under a confining pressure of 200 kPa. Simultaneously, to evaluate the computational performance of this technology, two modes were used on a portable computer (CPU: 13th Intel i7-13700H; GPU: NVIDIA GeForce RTX 4060 Laptop; number of cores: 14; number of threads: 20); CPU parallel computing and CPU+GPU heterogeneous parallel computing were employed respectively (total number of particles: 5010). By comparing the computational efficiency, the application potential and advantages of the flexible triaxial technology in the field of numerical computation were verified. The results show that this method can well simulate the shear mechanical behavior of silty clay in indoor triaxial experiments, such as... Figure 9 As shown.
[0065] By combining the CPU+GPU parallel computing architecture of the EDEM software, the computational efficiency is improved by 2 to 3 times compared to the pure CPU parallel computing mode, as shown in Table 1. Therefore, this invention enables the rapid construction of flexible triaxial numerical experiments of DEM and the precise application of confining pressure, effectively solving the problem of reduced computational efficiency caused by flexible particulate membrane technology.
[0066] Table 1. Comparison of computational efficiency based on EDEM software:
[0067]
[0068] Example 2
[0069] A flexible triaxial discrete element model construction system is provided for modeling and simulation experiments of flexible triaxial numerical simulation of EDEM. It is implemented by electronic device hardware with a central processing unit, such as a personal computer, smart terminal, local area network, or server. For implementation details in this example, please refer to [link to relevant documentation]. Figure 12 It includes a material creation and parameter setting module 61, a flexible particle mold creation module 62, a geometric model generation module 63, a sample generation module 64, and a secondary development simulation module 65. It includes:
[0070] The material creation and parameter setting module 61 is used to obtain the microscopic contact parameters of silty clay and rubber mold through calibration experiments or literature, create silty clay material and rubber mold material in EDEM, and set the microscopic contact parameters of silty clay material and rubber mold material.
[0071] In the process of creating silty clay material and rubber mold material in EDEM, the parameters to be set for creating silty clay material and rubber material must include at least Poisson's ratio, true density and shear modulus.
[0072] The microscopic contact parameters of silty clay materials and rubber mold materials both include at least the coefficient of restitution, the coefficient of static friction, and the coefficient of rolling friction. The microscopic contact parameters of rubber mold materials also include at least the normal stiffness per unit area, the tangential stiffness per unit area, the critical normal strength, and the critical tangential strength.
[0073] Setting the microscopic contact parameters for silty clay materials and rubber mold materials also includes:
[0074] Particle addition and parameter settings were performed for silty clay and rubber mold materials, respectively: including the definition of initial particle physical radius, contact radius, and particle size distribution; for discontinuously graded silty clay particles, the percentage content of each particle size was set based on particle size scaling and particle size distribution experimental results; the physical diameter of the rubber membrane particles was set by converting the actual thickness of the indoor rubber mold into an equivalent particle diameter, and the contact diameter of the rubber membrane particles was set as a multiple of the physical radius based on calibration experiments.
[0075] The flexible particle mold creation module 62 is used to create a flexible particle film by importing the geometric information of rubber mold particles from an external source using Python code based on the EDEM meta-particle function. The geometric information includes at least spatial coordinates and physical radius.
[0076] In this embodiment, the flexible particle mold creation module 62 is specifically used for:
[0077] Using Python code to import the sample dimensions and physical radii of the rubber membrane particles obtained from indoor triaxial experiments, the spatial coordinate information of the rubber membrane particles that make up the rubber membrane is generated. Then, the element-particle function of EDEM is used to import the spatial coordinate information generated in Python into EDEM to create a flexible membrane with the rubber membrane particles as the basic particle unit. The flexible membrane particles are arranged in a hexagonal pattern.
[0078] The geometric model generation module 63 is used to construct a geometric boundary model of a flexible granular membrane of the same size as the indoor triaxial instrument. The generated geometric boundary model is positioned in the virtual space corresponding to the position of the real experimental device through the spatial coordinate adjustment function, thus completing the positioning of the flexible granular membrane.
[0079] The sample generation module 64 is used to generate a flexible granular membrane using the static generation method of the particle factory. Based on the Rigid Link function of the particle factory, the flexible granular membrane is rigidly connected to the axially loaded piston block. After the flexible granular membrane is formed, the volume filling function of the particle factory is called to generate a set of silty clay sample particles with specified gradation characteristics.
[0080] The secondary development simulation module 65 is used to import .dll dynamic link library files based on secondary development into the particle contact model and particle volume force calculation model of EDEM to realize the simulation of triaxial consolidation and shear processes under preset confining pressure conditions.
[0081] In this embodiment, before the secondary development simulation module 65 and after the sample generation module 64, a dynamic link library generation module 66 is also included: a custom library CM_UDL for generating a particle contact model based on EDEM and a user-defined library PBF_UDL for particle volume force of EDEM as dynamic link library .dll files, which is used to generate a particle contact model based on EDEM and a particle volume force of EDEM based on the secondary development interface. CM_UDL stores the contact pairs and particle coordinate information of particles in the flexible membrane, so as to provide PBF_UDL with particle information to be obtained. PBF_UDL mainly implements the application of particle force in the flexible particle membrane under a preset confining pressure.
[0082] In this embodiment, the formula for applying particle force in the flexible particulate membrane is as follows: ;
[0083] In the formula: It is represented as the radial force vector acting on a single particle in a flexible particulate membrane; Represents the magnitude of the confining pressure; The cross-sectional area representing a spherical particle: Represents the radius of the particle; Represents the direction of radial force
[0084] Secondary development simulation module 65, specifically used for:
[0085] Import the .dll file into the particle contact model and particle volume force calculation model of EDEM respectively, set the force of the upper axial loading plate, and realize the triaxial isotropic consolidation operation.
[0086] Import the .dll file into the particle contact model and particle volume force calculation model of EDEM respectively. Switch the force control mode of the upper axial loading plate to constant speed loading. By setting the axial displacement rate, the silty clay sample is made to undergo axial deformation under the preset confining pressure to simulate the shearing process.
[0087] The flexible triaxial discrete element model construction system of this embodiment is implemented in the same way as the flexible triaxial discrete element model construction method described in Embodiment 1, and will not be repeated here.
[0088] Example 3
[0089] This invention relates to a computer-readable storage medium storing instructions that, when executed, produce a flexible triaxial discrete element model construction method according to Embodiment 1. The execution process and effects are the same as those described in Embodiment 1, and will not be repeated here.
[0090] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0091] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.
Claims
1. A method for constructing a flexible triaxial discrete element model, characterized in that, Modeling for flexible triaxial numerical simulation experiments of EDEM includes: The microscopic contact parameters of silty clay and rubber mold are obtained through calibration experiments or literature. Silty clay material and rubber mold material are created in EDEM, and the microscopic contact parameters of the silty clay material and the rubber mold material are set. Based on the EDEM element particle function, the geometric information of rubber mold particles is imported from the outside using Python code to create a flexible particle film, wherein the geometric information includes at least spatial coordinates and physical radius; A geometric boundary model of the flexible granular membrane with the same size as the indoor triaxial instrument is constructed. The generated geometric boundary model is positioned in virtual space corresponding to the position of the real experimental device by using the spatial coordinate adjustment function, thus completing the positioning of the flexible granular membrane. The flexible granular membrane is generated using the static generation method of the granulation plant. Based on the Rigid Link function of the granulation plant, the flexible granular membrane is rigidly connected to the axially loaded piston block. After the flexible granular membrane is formed, the volume filling function of the granulation plant is called to generate a set of silty clay sample particles with specified gradation characteristics. Import a .dll dynamic link library file based on secondary development into the particle contact model and the particle volume force calculation model of the EDEM to realize the simulation of triaxial consolidation and shear process under preset confining pressure conditions.
2. The method for constructing a flexible triaxial discrete element model according to claim 1, characterized in that, The creation of silty clay material and rubber mold material in EDEM specifically includes setting parameters for both the silty clay material and the rubber material, including at least Poisson's ratio, true density, and shear modulus. The microscopic contact parameters of the silty clay material and the microscopic contact parameters of the rubber mold material both include at least the coefficient of restitution, the coefficient of static friction, and the coefficient of rolling friction; the microscopic contact parameters of the rubber mold material also include at least the normal stiffness per unit area, the tangential stiffness per unit area, the critical normal strength, and the critical tangential strength. The setting of the fine contact parameters of the silty clay material and the fine contact parameters of the rubber mold material further includes: The silty clay material and the rubber mold material are respectively subjected to particle addition and particle parameter settings: including the definition of initial particle physical radius, contact radius and particle size distribution; for discontinuously graded silty clay particles, based on particle size scaling, the percentage content of each particle size is set according to the particle size distribution experiment results; the physical diameter of the rubber membrane particles is set by converting the actual thickness of the indoor rubber mold into an equivalent particle diameter, and the contact diameter of the rubber membrane particles is set as a multiple of the physical radius based on the calibration experiment.
3. The method for constructing a flexible triaxial discrete element model according to claim 2, characterized in that, The method of creating a flexible membrane based on EDEM element-level functionality, using Python code to import the geometric information of rubber mold particles from external sources, includes: Using Python code to import the sample dimensions and physical radii of the rubber membrane particles obtained from indoor triaxial experiments, the spatial coordinate information of the rubber membrane particles constituting the rubber membrane is generated. Then, the spatial coordinate information generated in Python is imported into EDEM using the element-particle function of EDEM to create a flexible membrane with the rubber membrane particles as the basic particle unit, wherein the flexible membrane particles are arranged in a hexagonal pattern.
4. The method for constructing a flexible triaxial discrete element model according to claim 1, characterized in that, Before importing a secondary-developed .dll dynamic link library file into the particle contact model and particle volume force calculation model of the EDEM to simulate the triaxial consolidation and shear process under the preset confining pressure conditions, the following steps are also included: Based on the secondary development interface of the EDEM, a custom library CM_UDL based on the particle contact model of the EDEM and a user-defined library PBF_UDL based on the particle volume force of the EDEM are generated as dynamic link library .dll files. Among them, CM_UDL stores the contact pairs and particle coordinate information of particles in the flexible membrane, so as to provide PBF_UDL to obtain particle information. PBF_UDL mainly implements the application of particle force in the flexible particle membrane under a preset confining pressure. The particle contact model and particle volume force calculation model of the EDEM are imported with a .dll dynamic link library file developed in a secondary manner to simulate triaxial consolidation and shear processes under preset confining pressure conditions, including: Import the .dll file into the particle contact model of the EDEM and the particle volume force calculation model of the EDEM respectively, set the force of the upper axial loading plate, and realize the triaxial isotropic consolidation operation; Import the .dll file into the particle contact model and the particle volume force calculation model of the EDEM respectively. Switch the force control mode of the upper axial loading plate to constant speed loading. By setting the axial displacement rate, the silty clay sample is made to undergo axial deformation under the preset confining pressure to simulate the shearing process.
5. The method for constructing a flexible triaxial discrete element model according to claim 4, characterized in that, The formula for applying particle force in the flexible particulate membrane is as follows: ; In the formula: It is represented as the radial force vector acting on a single particle in a flexible particulate membrane; Represents the magnitude of the confining pressure; The cross-sectional area representing the spherical particle: Represents the radius of the particle; It represents the direction of the radial force.
6. A flexible triaxial discrete element model construction system, characterized in that, Modeling and simulation for flexible triaxial numerical simulation experiments of EDEM, including: The material creation and parameter setting module is used to obtain the microscopic contact parameters of silty clay and rubber mold through calibration experiments or literature, create silty clay material and rubber mold material in EDEM, and set the microscopic contact parameters of the silty clay material and the rubber mold material. The flexible particle mold creation module is used to create a flexible particle film by importing the geometric information of rubber mold particles from an external source using Python code based on the EDEM element particle function. The geometric information includes at least spatial coordinates and physical radius. The geometric model generation module is used to construct a geometric boundary model of the flexible granular membrane with the same size as the indoor triaxial instrument. The generated geometric boundary model is positioned in the virtual space corresponding to the position of the real experimental device through the spatial coordinate adjustment function, thereby completing the positioning of the flexible granular membrane. The sample generation module is used to generate the flexible granular membrane using the static generation method of the particle factory. Based on the Rigid Link function of the particle factory, the flexible granular membrane is rigidly connected to the axially loaded piston block. After the flexible granular membrane is formed, the volume filling function of the particle factory is called to generate a set of silty clay sample particles with specified gradation characteristics. The secondary development simulation module is used to import .dll dynamic link library files based on secondary development into the particle contact model and particle volume force calculation model of the EDEM, so as to realize the simulation of triaxial consolidation and shear process under preset confining pressure conditions.
7. The flexible triaxial discrete element model construction system according to claim 6, characterized in that, The creation of silty clay material and rubber mold material in EDEM specifically includes setting parameters for both the silty clay material and the rubber material, including at least Poisson's ratio, true density, and shear modulus. The microscopic contact parameters of the silty clay material and the microscopic contact parameters of the rubber mold material both include at least the coefficient of restitution, the coefficient of static friction, and the coefficient of rolling friction. The microscopic contact parameters of the rubber mold material also include at least the normal stiffness per unit area, the tangential stiffness per unit area, the critical normal strength, and the critical tangential strength. The setting of the fine contact parameters of the silty clay material and the fine contact parameters of the rubber mold material further includes: The silty clay material and the rubber mold material are respectively subjected to particle addition and particle parameter settings: including the definition of initial particle physical radius, contact radius and particle size distribution; for discontinuously graded silty clay particles, based on particle size scaling, the percentage content of each particle size is set according to the particle size distribution experiment results; the physical diameter of the rubber film particles is set by converting the actual thickness of the indoor rubber mold into an equivalent particle diameter, and the contact diameter of the rubber film particles is set as a multiple of the physical radius based on the calibration experiment.
8. The flexible triaxial discrete element model construction system according to claim 7, characterized in that: The flexible particle mold creation module is specifically used for: Using Python code to import the sample dimensions and physical radii of the rubber membrane particles obtained from indoor triaxial experiments, the spatial coordinate information of the rubber membrane particles constituting the rubber membrane is generated. Then, the spatial coordinate information generated in Python is imported into EDEM using the element-particle function of EDEM to create a flexible membrane with the rubber membrane particles as the basic particle unit, wherein the flexible membrane particles are arranged in a hexagonal pattern.
9. A flexible triaxial discrete element model construction system according to claim 6, characterized in that, Before the secondary development simulation module, a dynamic link library generation module is also included: The dynamic link library generation module is used to generate a custom library CM_UDL based on the particle contact model of the EDEM and a user-defined library PBF_UDL based on the particle volume force of the EDEM as the dynamic link library .dll file based on the secondary development interface of the EDEM. CM_UDL stores the contact pairs and particle coordinate information of particles in the flexible membrane, so as to provide PBF_UDL with particle information acquisition. PBF_UDL mainly implements the application of particle force in the flexible particle membrane under a preset confining pressure. The secondary development simulation module is specifically used for: Import the .dll file into the particle contact model of the EDEM and the particle volume force calculation model of the EDEM respectively, set the force of the upper axial loading plate, and realize the triaxial isotropic consolidation operation; Import the .dll file into the particle contact model and the particle volume force calculation model of the EDEM respectively. Switch the force control mode of the upper axial loading plate to constant speed loading. By setting the axial displacement rate, the silty clay sample is made to undergo axial deformation under the preset confining pressure to simulate the shearing process.
10. A computer-readable storage medium, characterized in that: The storage medium stores instructions that, when executed, perform a flexible triaxial discrete element model construction method as described in any one of claims 1-5.