Rock fracture mechanical property prediction method and system based on multi-scale coupling

Abstract

This invention provides a method and system for predicting the mechanical properties of rock fractures based on multi-scale coupling, relating to the fields of rock mechanics and numerical simulation. The method includes: establishing an initial micro-crack network; extracting the stress state at the crack tip from the micro-crack network, calculating the fracture force, and determining the initiation, propagation, penetration, and branching of cracks based on propagation criteria, while updating the crack geometric boundary in real time; mapping the updated crack density, equivalent flexibility, and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and feeding back the macroscopic far-field stress boundary to the micro-crack network for bidirectional coupling iteration until convergence; extracting the macroscopic stress-strain response and mechanical property parameters of the rock mass. This invention, by initializing a micro-scale crack network, simulates the propagation, penetration, and interaction of cracks under different loading conditions, achieving coupled analysis at the micro and macro scales, and improving the accuracy and reliability of rock mechanics simulations.

Description

Technical Field

[0001] This invention relates to the fields of rock mechanics and numerical simulation, specifically to a method and system for predicting the mechanical properties of rock fractures based on multi-scale coupling. Background Technology

[0002] With the rapid development of geotechnical engineering, the demand for prediction of the mechanical properties and stability analysis of rock masses is increasing. In rock mechanics, the morphology, distribution and interaction of fracture networks have a decisive influence on the mechanical behavior of rock masses. However, existing numerical simulation methods have significant limitations in simulating the multi-scale behavior of fracture networks.

[0003] Traditional methods often rely on single-scale models, making it difficult to simultaneously capture the localized behavior of micro-fractures and the overall response of macro-rock masses. This is especially true under complex geological conditions, where the generation, propagation, and interaction of fractures are extremely complex, involving multiple mechanical mechanisms and scale effects. For example, fracture propagation at the micro-scale can lead to stress concentration and structural instability at the macro-scale. Furthermore, interactions between fractures, such as penetration, branching, and network formation, further increase the difficulty of simulation.

[0004] Existing technologies typically cannot fully consider the above factors, making it difficult to accurately simulate the generation, propagation, and interaction of rock fractures, especially their complex behavior under multi-scale conditions, resulting in significant deviations between simulation results and actual conditions. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method and system for predicting the mechanical properties of rock fractures based on multi-scale coupling. By initializing a microscale fracture network, the method simulates the expansion, penetration, and interaction of fractures under different loading conditions, thereby achieving coupled analysis of micro and macro scales and improving the accuracy and reliability of rock mechanics simulation.

[0006] According to some embodiments, the present invention adopts the following technical solution: A method for predicting the mechanical properties of rock fractures based on multi-scale coupling includes: The three-dimensional crack identification results of rock samples were obtained, an initial micro-crack network was established, and rock matrix parameters and crack interface parameters were obtained. Based on the rock matrix parameters and fracture interface parameters, the stress state at the fracture tip is extracted from the micro fracture network, the fracture force is calculated, and the initiation, propagation, penetration and branching of the fracture are determined according to the propagation criterion, and the fracture geometric boundary is updated in real time. A multi-scale coupling technique is used to map the updated crack density, equivalent flexibility and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and the macroscopic far-field stress boundary is fed back to the microscopic crack network for bidirectional coupling iteration until convergence. Based on the converged multi-scale coupling results, the macroscopic stress-strain response and mechanical property parameters of the rock mass are extracted, enabling the prediction of the macroscopic mechanical properties of the rock mass.

[0007] According to some embodiments, the present invention adopts the following technical solution: A multi-scale coupled system for predicting the mechanical properties of rock fractures includes: The module is configured to: acquire the three-dimensional crack identification results of rock samples, establish an initial micro-crack network, and acquire rock matrix parameters and crack interface parameters; The update module is configured to: extract the stress state at the crack tip in the micro-crack network based on the rock matrix parameters and crack interface parameters, calculate the fracture force, and determine the crack initiation, propagation, penetration and branching according to the propagation criterion, and update the crack geometric boundary in real time. The coupling module is configured to: use multi-scale coupling technology to map the updated crack density, equivalent flexibility and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and feed back the macroscopic far-field stress boundary to the microscopic crack network for bidirectional coupling iteration until convergence; The prediction module is configured to extract the macroscopic stress-strain response and mechanical property parameters of the rock mass based on the converged multi-scale coupling results, thereby predicting the macroscopic mechanical properties of the rock mass.

[0008] According to some embodiments, the present invention adopts the following technical solution: A computer program product includes a computer program that, when executed by a processor, implements the method for predicting the mechanical properties of rock fractures based on multi-scale coupling.

[0009] According to some embodiments, the present invention adopts the following technical solution: A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement the aforementioned method for predicting the mechanical properties of rock fractures based on multi-scale coupling.

[0010] According to some embodiments, the present invention adopts the following technical solution: An electronic device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to implement the method for predicting the mechanical properties of rock fractures based on multi-scale coupling.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention combines a detailed microscale fracture model with a macroscale continuous medium model to effectively simulate the evolution of rock fracture networks at different scales, achieving comprehensive simulation of the fracture network. Furthermore, the use of advanced multi-scale coupling technology enables information transfer between different scales, ensuring the consistency and accuracy of simulation results, improving simulation accuracy and computational efficiency, and making the method applicable to complex rock mechanics problems and large-scale geotechnical engineering projects. Attached Figure Description

[0012] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0013] Figure 1 This is a flowchart of the rock fracture mechanical property prediction method based on multi-scale coupling in Example 1.

[0014] Figure 2 This is a schematic diagram of the microcrack network in Example 1. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] Example 1 One embodiment of the present invention provides a method for predicting the mechanical properties of rock fractures based on multi-scale coupling. By initializing a microscale fracture network, the method simulates the propagation, penetration, and interaction of fractures under different loading conditions, achieving coupled analysis of micro and macro scales, and improving the accuracy and reliability of rock mechanics simulation. Specific steps include: Step S1: Based on the three-dimensional crack identification results of the rock sample, establish an initial micro-crack network and obtain the rock matrix parameters and crack interface parameters.

[0019] Furthermore, the specific methods for obtaining the three-dimensional crack identification results of the rock sample include: using one or more combinations of laser scanning, industrial CT scanning, microscopic observation, scanning electron microscopy observation, digital image processing, or thin section identification methods to identify and extract cracks inside and on the surface of the rock sample, and obtain information on crack length, aperture, dip angle, orientation, density, connectivity, fractal characteristics, and spatial distribution.

[0020] In a specific embodiment, the specific steps for obtaining microscale crack data information are as follows: 1.1 Rock Selection and Sample Collection Rock masses with complex fracture networks were selected as the research object. Sampling locations were determined through engineering survey data, and core or block samples were taken from the target rock mass to obtain rock samples that could characterize the in-situ fracture features.

[0021] 1.2 Acquisition of Microscopic Crack Network Information Multi-source testing and characterization were carried out on the collected rock samples. Methods such as laser scanning, industrial CT scanning, microscopic observation, scanning electron microscopy, digital image processing or thin section identification were used to identify and extract cracks inside and on the surface of the rock samples, and to obtain information on crack length, aperture, dip angle, orientation, density, connectivity, fractal characteristics and spatial distribution.

[0022] 1.3 Initial Crack Network Parametric Characterization The identified cracks are located by coordinates, extracted by boundaries, and analyzed by topological relationships. A crack geometric database is established, and the crack feature parameters are uniformly converted into input parameters that can be used for numerical modeling, including crack location, length, spacing, dip, dip angle, width, morphological features, and crack intersection relationships.

[0023] 1.4 Construction of Microscopic Crack Network A micro-fracture network matching the actual rock structure was established using modeling and simulation software. The micro-fracture network includes at least rock matrix units and initial fracture units embedded in the rock matrix, wherein the fracture units characterize the geometry and initial state of natural fractures or micro-defects, such as... Figure 2 As shown.

[0024] 1.5 Acquisition of Mechanical Parameters of Rock Matrix and Fractures To obtain the material parameters required for the model, mechanical parameters of the rock matrix and fracture interface are obtained through uniaxial compression tests, triaxial compression tests, Brazilian splitting tests, direct shear tests, and elastic wave tests. These parameters include elastic modulus, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, residual strength parameters, and interface stiffness parameters.

[0025] Step S2: In the microcrack network, extract the stress state in the neighborhood of the crack tip according to the calculation step, calculate the fracture force at the crack tip, determine the crack initiation, propagation, penetration and branching according to the preset propagation criterion, and update the crack geometric boundary in real time.

[0026] Furthermore, the specific steps for determining the initiation, propagation, penetration, and branching of cracks based on the propagation criterion include: solving for the stress intensity factor or equivalent fracture driving force parameter corresponding to mode I cracking, mode II slip, and mode III tearing, and making a judgment in combination with the fracture toughness, interface strength, and critical energy release rate of the rock material; when at least one fracture mode reaches a preset threshold, it is determined that the corresponding crack tip has entered the propagation state.

[0027] Furthermore, the real-time update of the crack geometric boundary adopts dynamic mesh update technology: by automatically identifying the cell boundaries crossed by the crack propagation path, performing a mesh splitting operation on the newly formed crack surface, generating mutually detached node or interface cells on both sides of the crack, and locally re-dividing the mesh in the affected area, so that the updated computational mesh is consistent with the actual physical boundary of the crack.

[0028] In a specific embodiment, the specific steps for simulating rock fracture propagation and interaction are as follows: 2.1 Extraction of stress state at crack tip and calculation of fracture parameters Based on the micro-crack network constructed in step S1, in each calculation step, the neighboring cells of the crack tip are traversed using the software's built-in programming language or script to extract the unit stress tensor, strain state, and displacement response of the crack, and the fracture mechanical parameters of the crack tip are calculated accordingly. The stress intensity factor or equivalent fracture driving force parameter corresponding to mode I cracking, mode II slip, and mode III tearing are solved respectively, and the fracture toughness, interface strength, and critical energy release rate of the rock material are combined to determine whether the current crack tip meets the crack initiation conditions. When at least one fracture mode reaches a preset threshold, the corresponding crack tip is determined to enter the propagation state.

[0029] 2.2. Determination of Rock Fracture Propagation Based on Multi-Mode Criteria Once the crack tip meets the propagation conditions, the preferred propagation direction and propagation step size are determined based on a multi-mode coupled fracture criterion: First, based on the combination relationship of fracture parameters in Modes I, II, and III, the maximum circumferential stress criterion is used to obtain the crack propagation direction. Crack propagation is determined based on the comparison between the equivalent fracture driving force at the crack tip and a preset critical fracture threshold. When the equivalent fracture driving force is greater than or equal to the critical fracture threshold, the crack tip is determined to have propagated. Then, based on the current step's loading increment, local stress level, energy release rate, and material fracture resistance, the propagation length or propagation speed of the crack tip is determined, and the crack geometry is updated in real time. The updated crack information includes the new coordinates of the crack tip, the new morphology of the crack trace or crack surface, the propagation direction, and the corresponding propagation rate data.

[0030] 2.3 Logical Determination of Rock Fracture Connections, Intersections, and Branches During crack propagation, the software uses a built-in programming language or script to traverse crack elements and monitor the spatial distance relationships between adjacent crack tips, between crack tips and existing crack surfaces, and between crack tips and model boundaries in real time. When the minimum spatial distance between adjacent crack tips is less than a preset breakthrough distance threshold, and the angle between the direction of the line connecting adjacent crack tips and the direction of local principal stress is less than a preset angle threshold, it is determined that adjacent cracks have achieved breakthrough. Simultaneously, the local energy release rate, stress redistribution characteristics, and path deflection trend at the crack tip are analyzed. When these exceed a preset branch threshold or meet the branching criteria, a new branch crack topology is generated on the current main crack propagation path. Its initial direction can be determined based on the direction of local principal stress, the direction of maximum circumferential stress, or the tangential disturbance direction of the crack surface.

[0031] 2.4 Real-time updating of crack network based on dynamic mesh As cracks continue to extend, penetrate, and branch, the original computational mesh may fail to accurately describe the newly generated crack boundaries. Therefore, a dynamic mesh update technique is employed to locally reconstruct the region adjacent to the crack. By using a built-in programming language or script, the software automatically identifies the cell boundaries traversed by the crack propagation path, performs mesh splitting operations on the newly formed crack surface, generates detached node or interface cells on both sides of the crack, and locally re-partitions the triangular mesh, tetrahedral mesh, or other discrete cells in the affected area, ensuring that the updated computational mesh remains consistent with the actual physical boundaries of the crack.

[0032] 2.5 Crack Interaction and Multi-Scale Coupling Analysis A crack network interaction analysis mechanism is established. First, the stress disturbance zones at the crack tips and near the crack surfaces in the current calculation step are identified. The stress shielding effect, stress enhancement effect, and crack co-propagation characteristics between cracks are calculated, and the local driving force parameters at the crack tips are corrected accordingly. Then, a coupling interface between the microcrack network and the macroscopic continuous medium is established. The strain energy release, local damage variables, or crack density increments generated by microcrack propagation are transformed into equivalent damage loads, equivalent stiffness reduction coefficients, or stress correction terms for macroscopic elements to update the stress and deformation fields of the macroscopic continuous medium model. Simultaneously, the stress concentration coefficient, boundary disturbance, or local strain concentration information caused by crack evolution in the macroscopic model is fed back to the microcrack model as boundary inputs for crack initiation and propagation in the next calculation step.

[0033] 2.6 Statistical Analysis and Results Output of Crack Network Evolution Characteristics After each computational step, the current crack network is statistically analyzed and quantitatively evaluated. Using a built-in programming language or script, the total length, area, or number of cracks per unit volume or area is statistically analyzed to obtain the crack density evolution pattern. A network topology graph is constructed based on crack nodes and their connections. Graph theory methods are used to calculate the connectivity, clustering coefficient, and main channel characteristics of the crack network to assess its connectivity and overall fragmentation. Furthermore, crack direction rose diagrams or direction frequency distribution maps are generated based on the spatial orientation information of the cracks to obtain the statistical law of crack number variation with azimuth angle. Mathematical statistics methods are then used to fit the crack size distribution function, direction distribution function, and connectivity distribution function.

[0034] Step S3: Map the crack density, equivalent flexibility, and local damage variables obtained in step S2 to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and feed back the far-field stress boundary calculated by the macroscopic continuum model to the microscopic crack network to perform bidirectional coupling iteration until the coupling interface meets the preset convergence condition.

[0035] Furthermore, the specific implementation of the bidirectional coupling iteration is as follows: an information mapping and transmission mechanism is constructed between the micro-scale model and the macro-scale model. The equivalent flexibility coefficient, equivalent damage variable or equivalent modulus degradation value caused by the propagation of micro-cracks are mapped to the macro-unit through spatial interpolation, volume averaging, energy equivalence or homogenization methods. At the same time, the far-field stress, strain or displacement boundary calculated by the macro-model is transmitted to the micro-model according to the coordinate mapping relationship, forming a bidirectional information transmission closed loop of "macro-scale response feedback to micro-cracks and micro-damage reverse correction of macro-stiffness".

[0036] In a specific embodiment, the specific steps of multi-scale coupled rock fracture propagation analysis are as follows: 3.1 Constructing Microscale and Macroscale Models Based on the development density, spatial distribution characteristics of cracks in the rock mass, and engineering analysis requirements, the applicable scope of microscale and macroscale models is clarified. The microscale model is mainly used to characterize the micromechanical behavior of cracks and their surrounding localized damage zones, while the macroscale model is mainly used to characterize the overall stress, deformation, and stability response of the rock mass within the main engineering structure. Microscale and macroscale models are constructed separately in a unified spatial coordinate system. The microscale model contains a crack network, and its geometry and crack parameters are constructed based on the crack size distribution function, direction distribution function, and connectivity statistics obtained in step 2. The macroscale model is a continuous medium model that does not explicitly characterize individual cracks, used to describe the stress, strain, and displacement field distributions within a large-scale engineering area.

[0037] In the microscale model, parameters such as normal stiffness, tangential stiffness, friction coefficient, bond strength, residual strength, and contact state are defined for the crack. Fracture toughness, critical energy release rate, or equivalent damage evolution criteria are defined for the crack tip to drive crack initiation, propagation, closure, slippage, and penetration. In the macroscale model, constitutive relations of the rock mass are established based on continuum mechanics theory, including linear elastic constitutive, elastoplastic constitutive, damage constitutive, or equivalent continuum constitutive considering anisotropy. These are used to simulate the overall mechanical response of engineering rock masses under external loads, boundary constraints, and crack evolution.

[0038] 3.2 Establish an information mapping and transmission mechanism A mechanism for information mapping and transmission between microscale and macroscale models is constructed. By traversing crack elements using a built-in programming language or script, equivalent compliance coefficients, equivalent damage variables, and equivalent modulus degradation values ​​caused by crack propagation, crack opening and closing, crack slip, and local damage evolution at the microscale are obtained. These are then mapped to the corresponding macroscale elements using spatial interpolation, volume averaging, energy equivalence, or homogenization methods to correct the stiffness matrix, constitutive parameters, or damage state variables of the macroscale elements. Simultaneously, far-field stress, strain, and displacement boundaries calculated from the macroscale model are transmitted to the microscale model according to coordinate mapping relationships, serving as boundary loading conditions for the next calculation step of the microscale crack model. This forms a two-way information transmission mechanism where "macroscale response is fed back to microscale cracks, and microscale damage inversely corrects macroscale stiffness."

[0039] 3.3 Multi-scale coupled simulation of rock fracture propagation After completing the multi-scale coupled analysis, the simulation results combining the micro-crack behavior and macro-rock mass response are output, including: the overall stress field, strain field and displacement field distribution of the rock mass; the local damage evolution process in the crack concentration area; the spatial variation law of the equivalent elastic modulus, equivalent stiffness and flexibility parameters of the rock mass; and the location and extent of potential failure zone, stress concentration zone and deformation concentration zone in the engineering area.

[0040] Step S4: Based on the converged multi-scale coupling results, extract the macroscopic stress-strain response, equivalent elastic modulus, equivalent Poisson's ratio, peak strength, residual strength, and potential failure zone distribution of the rock mass to predict the macroscopic mechanical properties of the rock mass.

[0041] Furthermore, the extraction of macroscopic stress-strain response and mechanical property parameters of the rock mass specifically includes: equivalent elastic modulus, deformation modulus, and unloading modulus calculated based on the slope of the linear segment, secant slope, or tangent slope of the stress-strain curve; equivalent Poisson's ratio calculated based on the ratio of transverse strain to axial strain; peak strength, residual strength, and yield strength extracted based on the stress, plasticity range, damage variables, and displacement characteristics of the elements in the macroscopic model; and the potential failure zone range, main fracture channel location, and instability initiation region determined by combining microscopic crack evolution information with the spatial correspondence between macroscopic damage concentration areas.

[0042] In a specific embodiment, the specific steps for predicting rock mechanical properties are as follows: 4.1 Data Extraction from Multi-Scale Coupled Simulation Results Based on step 3, data such as displacement vector, velocity, acceleration, strain tensor, stress tensor, plastic zone distribution, damage variables, and unbalanced forces of each monitoring node or target area are extracted from the macro-scale model; data such as crack width, normal opening, tangential slip displacement, crack length, crack area, crack three-dimensional coordinates, crack penetration relationship, crack density, crack direction distribution, and crack network connectivity are extracted from the micro-scale model.

[0043] 4.2 Calculation of macroscopic deformation parameters In a macroscopic continuous medium model, representative measuring points, lines, and surfaces are selected, and the average strain response of the rock mass is calculated based on their displacement changes during loading. Axial strain, transverse strain, and volumetric strain are calculated using the relative displacement of adjacent monitoring points within a unit gauge length, and the stress-strain curve of the rock mass is determined by combining this with the macroscopic stress components at the corresponding locations. Based on the slope of the linear segment, secant slope, or tangent slope of the stress-strain curve, the equivalent elastic modulus, deformation modulus, and unloading modulus of the rock mass are calculated; the equivalent Poisson's ratio of the rock mass is calculated based on the ratio of transverse strain to axial strain.

[0044] 4.3 Prediction of Macroscopic Intensity Parameters and Instability Characteristics Based on the coupled results of macroscopic and microscopic models, the overall bearing capacity and failure characteristics of rock masses are predicted. Based on the stress, plasticity range, damage variables, and displacement characteristics of elements in the macroscopic model, the initial yield point, peak bearing state, post-peak softening stage, and final instability state of the rock under given boundary conditions and loading paths are determined, and parameters such as peak strength, residual strength, and yield strength are extracted. Simultaneously, by combining the evolution results of crack propagation, penetration, branching, and connectivity networks in the microscopic crack model, the dominant failure modes of the rock mass are identified, including tensile failure, shear failure, combined tensile-shear failure, local dilatational instability, or overall instability modes controlled by penetrating cracks. By spatially mapping the microscopic crack evolution information with the macroscopic damage concentration area, the potential failure zone range, the location of the main fracture channel, and the instability initiation region can be further determined.

[0045] 4.4 Output of Macroscopic Mechanical Property Prediction Results Output the predicted results of the macroscopic mechanical properties of the rock mass, which include at least: equivalent elastic modulus, equivalent Poisson's ratio, peak strength, residual strength, plastic zone range, damage concentration zone range, and potential main fracture channel location.

[0046] Example 2 One embodiment of the present invention provides a rock fracture mechanical property prediction system based on multi-scale coupling, comprising: The module is configured to: acquire the three-dimensional crack identification results of rock samples, establish an initial micro-crack network, and acquire rock matrix parameters and crack interface parameters; The update module is configured to: extract the stress state at the crack tip in the micro-crack network based on the rock matrix parameters and crack interface parameters, calculate the fracture force, and determine the crack initiation, propagation, penetration and branching according to the propagation criterion, and update the crack geometric boundary in real time. The coupling module is configured to: use multi-scale coupling technology to map the updated crack density, equivalent flexibility and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and feed back the macroscopic far-field stress boundary to the microscopic crack network for bidirectional coupling iteration until convergence; The prediction module is configured to extract the macroscopic stress-strain response and mechanical property parameters of the rock mass based on the converged multi-scale coupling results, thereby predicting the macroscopic mechanical properties of the rock mass.

[0047] Example 3 One embodiment of the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the rock fracture mechanical property prediction method based on multi-scale coupling.

[0048] Example 4 In one embodiment of the present invention, a non-transitory computer-readable storage medium is provided for storing computer instructions. When the computer instructions are executed by a processor, the method for predicting the mechanical properties of rock fractures based on multi-scale coupling is implemented.

[0049] Example 5 One embodiment of the present invention provides an electronic device, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to implement the rock fracture mechanical property prediction method based on multi-scale coupling.

[0050] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0051] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0052] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for predicting the mechanical properties of rock fractures based on multi-scale coupling, characterized in that, include: The three-dimensional crack identification results of rock samples were obtained, an initial micro-crack network was established, and rock matrix parameters and crack interface parameters were obtained. Based on the rock matrix parameters and fracture interface parameters, the stress state at the fracture tip is extracted from the micro fracture network, the fracture force is calculated, and the initiation, propagation, penetration and branching of the fracture are determined according to the propagation criterion, and the fracture geometric boundary is updated in real time. A multi-scale coupling technique is used to map the updated crack density, equivalent flexibility and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and the macroscopic far-field stress boundary is fed back to the microscopic crack network for bidirectional coupling iteration until convergence. Based on the converged multi-scale coupling results, the macroscopic stress-strain response and mechanical property parameters of the rock mass are extracted, enabling the prediction of the macroscopic mechanical properties of the rock mass.

2. The method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in claim 1, characterized in that, The specific methods for obtaining the three-dimensional crack identification results of rock samples include: using one or more combinations of laser scanning, industrial CT scanning, microscopic observation, scanning electron microscopy observation, digital image processing, or thin section identification methods to identify and extract cracks inside and on the surface of the rock sample, and obtain information on crack length, aperture, dip angle, direction, density, connectivity, fractal characteristics, and spatial distribution.

3. The method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in claim 1, characterized in that, The specific steps for determining the initiation, propagation, penetration, and branching of cracks based on the propagation criterion include: solving for the stress intensity factor or equivalent fracture driving force parameter corresponding to Mode I cracking, Mode II slip, and Mode III tearing, and making a judgment based on the fracture toughness, interface strength, and critical energy release rate of the rock material; when at least one fracture mode reaches a preset threshold, it is determined that the corresponding crack tip has entered the propagation state.

4. The method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in claim 1, characterized in that, The real-time update of the crack geometry boundary adopts dynamic mesh update technology: by automatically identifying the cell boundaries crossed by the crack propagation path, performing a mesh splitting operation on the newly formed crack surface, generating mutually detached node or interface cells on both sides of the crack, and locally re-dividing the mesh in the affected area, so that the updated computational mesh is consistent with the actual physical boundary of the crack.

5. The method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in claim 1, characterized in that, The specific implementation of the bidirectional coupling iteration is as follows: an information mapping and transmission mechanism is constructed between the micro-scale model and the macro-scale model. The equivalent flexibility coefficient, equivalent damage variable or equivalent modulus degradation value caused by the propagation of micro-cracks are mapped to the macro-unit through spatial interpolation, volume averaging, energy equivalence or homogenization methods. At the same time, the far-field stress, strain or displacement boundary calculated by the macro-model is transmitted to the micro-model according to the coordinate mapping relationship, forming a bidirectional information transmission closed loop of "macro-scale response feedback to micro-cracks and micro-damage reverse correction of macro-stiffness".

6. The method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in claim 1, characterized in that, The extracted macroscopic stress-strain response and mechanical property parameters of the rock mass specifically include: the equivalent elastic modulus, deformation modulus, and unloading modulus calculated based on the slope of the linear segment, secant slope, or tangent slope of the stress-strain curve; the equivalent Poisson's ratio calculated based on the ratio of transverse strain to axial strain; the peak strength, residual strength, and yield strength extracted based on the stress, plastic range, damage variables, and displacement characteristics of the elements in the macroscopic model; and the potential failure zone range, the location of the main fracture channel, and the instability initiation region determined by combining the microscopic crack evolution information with the spatial correspondence of the macroscopic damage concentration area.

7. A rock fracture mechanical property prediction system based on multi-scale coupling, characterized in that, include: The module is configured to: acquire the three-dimensional crack identification results of rock samples, establish an initial micro-crack network, and acquire rock matrix parameters and crack interface parameters; The update module is configured to: extract the stress state at the crack tip in the micro-crack network based on the rock matrix parameters and crack interface parameters, calculate the fracture force, and determine the crack initiation, propagation, penetration and branching according to the propagation criterion, and update the crack geometric boundary in real time. The coupling module is configured to: use multi-scale coupling technology to map the updated crack density, equivalent flexibility and local damage variables to the stiffness reduction parameters of the corresponding elements in the macroscopic continuum model, and feed back the macroscopic far-field stress boundary to the microscopic crack network for bidirectional coupling iteration until convergence; The prediction module is configured to extract the macroscopic stress-strain response and mechanical property parameters of the rock mass based on the converged multi-scale coupling results, thereby predicting the macroscopic mechanical properties of the rock mass.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in any one of claims 1-6.

9. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in any one of claims 1-6.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform the method for predicting the mechanical properties of rock fractures based on multi-scale coupling as described in any one of claims 1-6.

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