Transverse isotropic rock mass discrete element model parameter checking method and system

Abstract

The application relates to the technical field of coal mining, and provides a transversely isotropic rock mass discrete element model parameter checking method and system. In the analysis method, a complete matrix model Matrix of a layered rock mass is generated based on a parallel combination model, the matrix modulus of the matrix model Matrix is calibrated by adjusting the bonding stiffness of the bonded particles of the matrix model Matrix, and the compressive strength of the matrix model Matrix is calibrated by adjusting the strength parameter of the bonded particles; a smooth contact interface for simulating the contact between the bedding planes and weak planes of the layered rock mass is inserted into the matrix model Materix based on a smooth contact model, so that a rock mass model Mass of the layered rock mass is generated; when the inclination angle of the bedding planes of the rock mass model Mass is (0°, 90°), the compressive strength of the rock mass model Mass is adjusted by adjusting the strength parameter of the smooth contact interface, so that the calibration process of the layered rock mass model is repeatable.

Description

Technical Field

[0001] This application relates to the field of coal mining technology, and in particular to a method and system for verifying parameters of a discrete element model of transversely isotropic rock mass. Background Technology

[0002] The Discrete Element Method (DEM) has a long history of application in geological materials and rock mechanics, especially in simulating the propagation of cracks in granular materials and rocks. It is widely used to simulate and study the mechanical behavior of materials such as rocks and soils, with the Bound Particle Model (BPM) being the most widely used.

[0003] Existing calibration methods for composite materials based on the discrete element method (DEM) using parallel bonded models (PBMs), especially those using both constitutive models and smooth joint models (SJMs), typically require extensive trial-and-error processes. The relationship between the model's microscopic parameters and macroscopic behavior is complex and linear, necessitating repeated adjustments to multiple parameters. This is particularly problematic when the model involves material stiffness and strength in different directions, significantly increasing the number of trials. Furthermore, this trial-and-error approach is not only complex and time-consuming but also difficult to systematize. During calibration, the coupling relationships between parameters mean that adjusting one parameter often affects others, increasing the complexity of the calibration and compromising repeatability and efficiency.

[0004] Therefore, there is an urgent need to provide a technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this application is to provide a method and system for verifying the parameters of a discrete element model of transversely isotropic rock mass, so as to solve or alleviate the problems existing in the prior art.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] This application provides a method for verifying the parameters of a discrete element model of a transversely isotropic rock mass, including: step S101, generating a complete matrix model of the layered rock mass based on a parallel bonding model, calibrating the matrix modulus of the matrix model matrix by adjusting the bonding stiffness of the bonding particles of the matrix model matrix, and calibrating the compressive strength of the matrix model matrix by adjusting the strength parameters of the bonding particles.

[0008] Step S102: Based on the smooth contact model, insert a smooth contact interface into the matrix model Matrix to simulate the contact between the bedding planes and weak surfaces of the layered rock mass, and generate the rock mass model Ms of the layered rock mass;

[0009] Step S103: In response to the bedding plane dip angle of the rock mass model Mass being (0°, 90°), the compressive strength of the rock mass model Mass is adjusted by adjusting the strength parameters of the smooth contact interface.

[0010] Preferably, in step S101, calibrating the matrix modulus of the matrix model Matrix by adjusting the bonding stiffness between the bonding particles of the matrix model Matrix specifically involves adjusting the normal stiffness k of the bonding particles in the matrix model Matrix. n,pbm and shear stiffness k s,pbm The effective modulus E of the matrix model Matrix pbm Perform calibration.

[0011] Preferably, in step S101, calibrating the compressive strength of the matrix model by adjusting the strength parameters of the bonding particles specifically involves adjusting the tensile strength σ of the bonding particles in the matrix model. t,pbm Cohesion c pbm and friction angle μ pbm The compressive strength of the matrix model is calibrated.

[0012] Preferably, in step S103, in response to the dip angle of the bedding plane of the rock mass model Mass being (0°, 90°), the compressive strength of the rock mass model Mass is adjusted by adjusting the strength parameters of the smooth contact interface. Specifically, this is achieved by adjusting the normal stiffness k of the smooth contact interface. n,sj and tangential stiffness k s,sj The matrix modulus E0 parallel to the bedding plane and the rock mass modulus E1 perpendicular to the bedding plane in the rock mass model Mass are... 90 Make adjustments;

[0013] Adjusting the tensile strength σ of the smooth contact interface t,sj Cohesion c sj and friction angle μ sj The uniaxial compressive strength in the rock mass model Mass.

[0014] Preferably, the step of adjusting the normal stiffness k of the smooth contact interface... n,sj and tangential stiffness k s,sjThe matrix modulus E0 parallel to the bedding plane and the rock mass modulus E1 perpendicular to the bedding plane in the rock mass model Mass are... 90 Adjustments are made, including: in response to the error between the matrix modulus E0 in the rock mass model Mass parallel to the bedding plane and the matrix modulus E0 in the layered rock mass parallel to the bedding plane greater than a preset first threshold, the tangential stiffness k of the smooth contact interface is adjusted. s,sj Make adjustments;

[0015] In response to the rock mass modulus E perpendicular to the bedding plane in the rock mass model Mass 90 The rock mass modulus E perpendicular to the bedding plane in the aforementioned rock mass 90 If the error is greater than a preset second threshold, then the normal stiffness k of the smooth contact interface is... n,sj Adjustments will be made.

[0016] Preferably, the tensile strength σ of the smooth contact interface is adjusted. t,sj Cohesion c sj and friction angle μ sj The uniaxial compressive strength in the rock mass model Mass includes: responding to the error between the uniaxial compressive strength UCS0 parallel to the loading direction in the rock mass model Mass and the uniaxial compressive strength UCS0 parallel to the loading direction in the layered rock mass being greater than a preset third threshold, then maintaining the friction angle μ of the smooth contact interface in the rock mass model Mass. sj The tensile strength σ remains unchanged. t,si Cohesion c sj Adjustments will be made.

[0017] This application also provides a parameter verification system for a discrete element model of transversely isotropic rock mass, including:

[0018] The matrix model and matrix stiffness adjustment unit are configured to generate the matrix model Matrix of the layered rock mass based on the parallel bonding model, and to calibrate the matrix modulus of the matrix model Matrix by adjusting the bonding stiffness of the bonding particles of the matrix model Matrix, and to calibrate the compressive strength of the matrix model Matrix by adjusting the strength parameters of the bonding particles.

[0019] The rock mass model generation unit is configured to insert a smooth contact interface into the matrix model Matrix based on a smooth contact model to simulate the contact between the bedding planes and weak surfaces of the layered rock mass, thereby generating the rock mass model Mass of the layered rock mass.

[0020] The bedding plane stiffness adjustment unit is configured to adjust the compressive strength of the rock mass model Mass by adjusting the strength parameters of the smooth contact interface in response to the bedding plane dip angle of the rock mass model Mass being (0°, 90°).

[0021] Beneficial effects:

[0022] In the parameter verification method of the transversely isotropic rock mass discrete element model provided in this application embodiment, firstly, a complete matrix model Matrix of the layered rock mass is generated based on the parallel bonding model, and the matrix modulus of the matrix model Matrix is ​​calibrated by adjusting the bonding stiffness of the bonding particles of the matrix model Matrix, and the compressive strength of the matrix model Matrix is ​​calibrated by adjusting the strength parameters of the bonding particles; then, a smooth contact interface simulating the contact between the bedding plane and the weak surface of the layered rock mass is inserted into the matrix model Matrix based on the smooth contact model to generate the rock mass model Mass of the layered rock mass; when the dip angle of the bedding plane of the rock mass model Mass is (0°, 90°), the compressive strength of the rock mass model Mass is adjusted by adjusting the strength parameters of the smooth contact interface.

[0023] Therefore, in the process of simulating layered rock masses, the calibration process of the layered rock mass model parameters is divided into multiple independent calibration steps by combining the parallel bonding model and the smooth contact model. In each independent calibration step, different parameters of the layered rock mass model are calibrated independently in sequence. The calibration process has multi-scale and multi-directional adaptability, so that the calibration of the layered rock mass model is no longer affected by the size of the model. At the same time, it effectively avoids parameter coupling during the calibration of layered rock mass models in the prior art, which not only simplifies the parameter adjustment process of the model and improves the model calibration efficiency, but also makes the calibration process of the layered rock mass model repeatable. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0025] in:

[0026] Figure 1 This is a flowchart illustrating a method for verifying parameters of a discrete element model of transversely isotropic rock mass according to some embodiments of this application;

[0027] Figure 2 This is a schematic diagram of a mechanical constitutive model of a smooth contact surface in a transversely isotropic rock mass, provided according to some embodiments of this application.

[0028] Figure 3This is a schematic diagram of a smooth contact surface model in a discrete element model of transversely isotropic rock mass provided according to some embodiments of this application;

[0029] Figure 4 This is a schematic diagram of the structure of a parameter verification system for a discrete element model of transversely isotropic rock mass provided according to some embodiments of this application. Detailed Implementation

[0030] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will understand that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0031] Existing calibration processes for incorporating particle (i.e., binder particle) models in geological material simulations are only applicable to single contact models (such as parallel bonded models or soft contact models). However, for transversely isotropic materials (such as shale), multiple contact models are typically required to simulate complex mechanical behaviors, such as the strength and stiffness within layers. When a model includes multiple contact models (such as parallel bonded models and smooth contact models), existing numerical simulation techniques can usually only be applied to a single contact model and cannot simultaneously consider the different mechanical properties of the material within the layers. This is especially true when dealing with transversely isotropic materials (such as shale and coal seams), where accurately calibrating multiple parameters in the model is difficult when handling the isotropy of the material.

[0032] Based on this, embodiments of this application provide a parameter verification method for a discrete element model of transversely isotropic rock mass. By dividing the calibration process into multiple independent steps and adjusting different parameters in each step, the method ensures that parameter changes in each step have minimal impact on parameters in other steps, simplifying the model parameter tuning process and improving calibration efficiency. Figures 1 to 3 As shown, the parameter verification method for the discrete element model of the transversely isotropic rock mass includes:

[0033] Step S101: Generate a complete matrix model Matrix of the layered rock mass based on the parallel bonding model, and calibrate the matrix model Matrix by adjusting the bonding stiffness of the bonding particles of the matrix model Matrix, and calibrate the compressive strength of the matrix model Matrix by adjusting the strength parameters of the bonding particles.

[0034] In the parallel bonding model, the simulated materials of the layered rock mass are connected by bonding particles to simulate the formation and propagation of rock cracks. However, the parallel bonding model can only simulate a single contact and cannot simultaneously simulate and calibrate the properties of the material matrix and bedding planes. Here, using the parallel bonding model, the elastic modulus and stiffness of the material matrix are simulated through the bonding relationship between particles (simulated materials), generating a complete matrix model of the layered rock mass. The matrix model of the matrix model is calibrated by adjusting the bonding stiffness of the bonding particles in the matrix model, thus retaining the advantage of matrix stiffness in the parallel bonding model.

[0035] Specifically, adjust the normal stiffness k of the bonding particles in the matrix model. n,pbm and shear stiffness k s,pbm The effective modulus E of the matrix model pbm Calibration is performed to lay the foundation for subsequent calibration of the bedding planes. Simultaneously, the strength parameters of the bonding particles (tensile strength σ) are adjusted. t,pbm Cohesion c pbm and friction angle μ pbm The compressive strength of the matrix model is calibrated. That is, the tensile strength σ of the bonding particles is calibrated. t,pbm Cohesion c pbm and friction angle μ pbm The adjustment is used to calibrate the uniaxial compressive strength of the matrix model.

[0036] First, the tensile strength σ of the bonding particles is determined. t,pbm Cohesion c pbm and friction angle μ pbm Using theoretical laboratory data, the compressive strength of the matrix model is compared with the actual laboratory strength. If the compressive strength of the matrix model is greater than the actual laboratory strength, the tensile strength σ of the binder particles is calculated based on the ratio of the compressive strength of the matrix model to the actual laboratory strength. t,pbm Cohesion c pbm and friction angle μ pbm The value is reduced proportionally; conversely, if the compressive strength of the matrix model is less than the actual laboratory strength, then the tensile strength σ of the bonding particles is reduced proportionally according to the ratio of the compressive strength of the matrix model to the actual laboratory strength. t,pbm Cohesion c pbm and friction angle μ pbm The value is increased proportionally.

[0037] Step S102: Based on the smooth contact model, insert a smooth contact interface in the matrix model Matrix to simulate the contact between the bedding planes and weak planes of the layered rock mass, and generate the rock mass model Mass of the layered rock mass.

[0038] In this application, the elasticity and strength of the material matrix are simulated through the bonding relationship between the bonding particles in the parallel bonding model. The matrix modulus is adjusted through the parallel bonding model, while retaining the matrix stiffness advantage of the parallel bonding model. Then, a smooth contact model is inserted into the parallel bonding model to simulate the contact between bedding planes and weak surfaces in the layered rock mass. This allows for the handling of the normal stiffness and shear stiffness on the weak surfaces of the layered rock mass, enabling the generated rock mass model (Mass) to more accurately reflect the isotropic behavior of the material, thereby achieving precise control over the mechanical properties in different directions (parallel to the bedding plane and perpendicular to the bedding plane).

[0039] Step S103: In response to the dip angle of the bedding plane of the rock mass model Mass being (0°, 90°), the compressive strength of the rock mass model Mass is adjusted by adjusting the strength parameters of the smooth contact interface.

[0040] When the bedding plane dip angle of the rock mass model Mass is in the interval (0°, 90°), the normal stiffness k of the smooth contact surface is adjusted. n,sj and tangential stiffness k s,sj For the matrix modulus E0 parallel to the bedding plane and the rock mass modulus E1 perpendicular to the bedding plane in the rock mass model Mass, 90 Adjustments are made. Specifically, when the error between the matrix modulus E0 parallel to the bedding plane in the rock mass model Mass and the matrix modulus E0 parallel to the bedding plane in the layered rock mass exceeds a preset first threshold, the tangential stiffness k of the smooth contact interface is adjusted. s,sj Adjustments are made; when the rock mass modulus E in the rock mass model Mass is perpendicular to the bedding plane... 90 Rock modulus E perpendicular to the bedding plane in the layered rock mass 90 If the error is greater than a preset second threshold, then the normal stiffness k of the smooth contact interface... n,sj Adjustments will be made.

[0041] Therefore, the interaction between normal stiffness and shear stiffness was fully considered during the model calibration process, enabling the model to not only perform well in the bedding plane directions at 0° (parallel to the bedding plane direction) and 90° (perpendicular to the bedding plane direction), but also to exhibit relatively accurate mechanical behavior at other bedding plane dip angles (such as 45° and 60°), effectively improving the model's predictive performance and practicality, and making it more reliable in engineering applications.

[0042] Furthermore, when the bedding planes of the rock mass model Mass dip within the range (0°, 90°), the tensile strength σ of the smooth contact interface can be adjusted. t,sj Cohesion c sj and friction angle μ sj The uniaxial compressive strength in the rock mass model Mass is considered. Specifically, if the error between the uniaxial compressive strength UCS0 parallel to the loading direction in the rock mass model Mass and the uniaxial compressive strength UCS0 parallel to the loading direction in the layered rock mass is greater than a preset third threshold, then the friction angle μ of the smooth contact interface in the rock mass model Mass is maintained. sj Unchanged, for tensile strength σ t,si Cohesion c sj Adjustments will be made.

[0043] In this application, the matrix stiffness of the layered rock mass matrix model is adjusted by simulating the elastic modulus and strength of the material matrix through the bonding relationship between the bonding particles in the parallel bonding model. A smooth contact interface is inserted into the matrix model matrix to simulate the contact between the bedding planes and weak surfaces of the layered rock mass. Furthermore, the bedding plane stiffness of the rock mass model is adjusted by measuring the normal and shear stiffness on the weak surfaces at the smooth contact interface. This makes parameter adjustments more targeted, reduces the coupling effects of parameter interactions during complex model calibration, improves the transparency of parameter adjustments, reduces unnecessary parameter iterations, and enhances model stability. By simultaneously adjusting the matrix parameters in the parallel bonding model and the weak surface parameters in the smooth contact model, the model exhibits more consistent behavior under different directions and stress conditions.

[0044] By combining parallel bonding and smooth contact models, the calibration process of the layered rock mass model parameters is divided into multiple independent calibration steps. Within each independent calibration step, different parameters of the layered rock mass model are calibrated independently in sequence. This calibration process is adaptable to multiple scales and directions, making the calibration of the layered rock mass model independent of the model's scale. Simultaneously, it effectively avoids parameter coupling during layered rock mass model calibration in existing technologies, simplifying the model parameter tuning process, improving calibration efficiency, and ensuring repeatability. This significantly enhances the model's adaptability. Compared to traditional trial-and-error methods, it shortens calibration time, improves calibration efficiency, and makes the model calibration repeatable and standardized, reducing the influence of human experience.

[0045] This application also provides a parameter verification system for a discrete element model of transversely isotropic rock mass, such as... Figure 4 As shown, the system includes:

[0046] The matrix model and matrix stiffness adjustment unit 401 are configured to generate a matrix model Matrix of the layered rock mass based on the parallel bonding model, and to calibrate the matrix modulus of the matrix model Matrix by adjusting the bonding stiffness of the bonding particles of the matrix model Matrix, and to calibrate the compressive strength of the matrix model Matrix by adjusting the strength parameters of the bonding particles.

[0047] Rock mass model generation unit 402 is configured to insert a smooth contact interface into the matrix model Matrix based on a smooth contact model to simulate the contact between the bedding planes and weak surfaces of the layered rock mass, thereby generating the rock mass model Mass of the layered rock mass.

[0048] The bedding stiffness adjustment unit 403 is configured to respond to the bedding dip angle of the rock mass model Mass as (0°, 90°) and adjust the compressive strength of the rock mass model Mass by adjusting the strength parameters of the smooth contact interface.

[0049] The parameter verification system for the discrete element model of transverse isotropic rock mass provided in this application embodiment can realize the steps and process of the parameter verification method for the discrete element model of transverse isotropic rock mass in any of the above embodiments, and achieve the same technical effect, which will not be described in detail here.

[0050] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0052] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for verifying parameters of a discrete element model of transversely isotropic rock mass, characterized in that, The calibration process for model parameters is divided into multiple independent calibration steps, and in each independent calibration step, different parameters of the layered rock mass model are independently calibrated in sequence. The method includes: Step S101: Generate a complete matrix model of the layered rock mass based on the parallel bonding model. And by adjusting the matrix model The bonding stiffness of the bonding particles on the matrix model The matrix modulus was calibrated, and the matrix model was adjusted by modifying the strength parameters of the bonding particles. The compressive strength was calibrated. Step S102: Based on the smooth contact model in the matrix model A smooth contact interface is inserted to simulate the contact between the bedding planes and weak surfaces of the layered rock mass, thereby generating a rock mass model of the layered rock mass. ; Step S103, in response to the rock mass model The dip angle of the bedding plane is By adjusting the strength parameters of the smooth contact interface, the rock mass model... Adjust the compressive strength; in, In response to the rock mass model Matrix modulus parallel to the bedding plane The matrix modulus parallel to the bedding plane in the rock mass If the error is greater than a preset first threshold, then the tangential stiffness of the smooth contact interface is... Make adjustments; In response to the rock mass model Rock mass modulus perpendicular to the bedding plane The rock mass modulus perpendicular to the bedding plane in the aforementioned rock mass If the error is greater than a preset second threshold, then the normal stiffness of the smooth contact interface is... Adjustments will be made.

2. The parameter verification method for the discrete element model of transversely isotropic rock mass according to claim 1, characterized in that, In step S101, the matrix model is adjusted. The bonding stiffness between the bonding particles on the matrix model The matrix modulus was calibrated, specifically as follows: Adjust the matrix model Normal stiffness of medium-bonded particles and shear stiffness For the matrix model effective modulus Perform calibration.

3. The parameter verification method for the discrete element model of transversely isotropic rock mass according to claim 1, characterized in that, In step S101, the matrix model is adjusted by modifying the strength parameters of the bonding particles. The compressive strength is calibrated as follows: Adjust the matrix model Tensile strength of medium-bonded particles Cohesion and friction angle For the matrix model The compressive strength is calibrated.

4. The parameter verification method for the discrete element model of transversely isotropic rock mass according to claim 1, characterized in that, In step S103, the response to the rock mass model The dip angle of the bedding plane is By adjusting the strength parameters of the smooth contact interface, the rock mass model... Adjustments to compressive strength also include: Adjusting the tensile strength of the smooth contact interface Cohesion and friction angle For the rock mass model The uniaxial compressive strength is adjusted.

5. The parameter verification method for the discrete element model of transversely isotropic rock mass according to claim 4, characterized in that, The tensile strength of the smooth contact interface is adjusted. Cohesion and friction angle For the rock mass model The uniaxial compressive strength in the sample is adjusted, including: In response to the rock mass model Uniaxial compressive strength parallel to the loading direction Uniaxial compressive strength parallel to the loading direction in the rock mass If the error is greater than a preset third threshold, then the rock mass model is maintained. The friction angle of the smooth contact interface described in the text The tensile strength remains unchanged. Cohesion Adjustments will be made.

6. A parameter verification system for a discrete element model of transversely isotropic rock mass, characterized in that, The calibration process for model parameters is divided into multiple independent calibration steps. In each independent calibration step, different parameters of the layered rock mass model are independently calibrated in sequence. The system includes: The matrix model and matrix stiffness adjustment unit are configured to generate a matrix model of layered rock masses based on a parallel combined model. And by adjusting the matrix model The bonding stiffness of the bonding particles on the matrix model The matrix modulus was calibrated, and the matrix model was adjusted by modifying the strength parameters of the bonding particles. The compressive strength was calibrated. The rock mass model generation unit is configured to be based on the smooth contact model in the matrix model. A smooth contact interface is inserted to simulate the contact between the bedding planes and weak surfaces of the layered rock mass, thereby generating a rock mass model of the layered rock mass. ; The bedding plane stiffness adjustment unit is configured to respond to the rock mass model. The dip angle of the bedding plane is By adjusting the strength parameters of the smooth contact interface, the rock mass model... Adjust the compressive strength; in, In response to the rock mass model Matrix modulus parallel to the bedding plane The matrix modulus parallel to the bedding plane in the rock mass If the error is greater than a preset first threshold, then the tangential stiffness of the smooth contact interface is... Make adjustments; In response to the rock mass model Rock mass modulus perpendicular to the bedding plane The rock mass modulus perpendicular to the bedding plane in the aforementioned rock mass If the error is greater than a preset second threshold, then the normal stiffness of the smooth contact interface is... Adjustments will be made.

Images