A method, medium and device for determining a creep parameter of a fractured rock mass based on an equivalent medium theory

Abstract

This invention discloses a method, medium, and equipment for determining creep parameters of fractured rock masses based on the equivalent medium theory. The method includes: constructing a random fracture network model of fractured rock masses containing multiple sets of structural planes, and generating numerical models of fractured rock masses of different sizes; embedding the viscoelastic-plastic constitutive model of the structural planes into discrete element numerical calculation software; applying constant loads to the numerical models of fractured rock masses of different sizes, conducting numerical creep tests on the fractured rock masses, and obtaining the creep deformation time history curves of each numerical model; performing parameter inversion on the creep curves of fractured rock mass models of different sizes to determine the size range of the CREV (Crew Characterization Equivalent Value) of the fractured rock mass creep characterization unit; obtaining the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass; and applying the obtained parameters to long-term slope deformation analysis. This method provides a more reliable theoretical basis for the long-term stability assessment and safety prediction of hydropower, mining, and tunnel projects.

Description

Technical Field

[0001] This invention relates to the fields of geotechnical engineering and rock mechanics, specifically to a method, medium, and equipment for determining creep parameters of fractured rock masses based on the equivalent medium theory. Background Technology

[0002] In the long-term stability assessment of rock mass engineering, accurately obtaining its creep parameters is crucial, but traditional methods face significant limitations. Laboratory tests are constrained by sample size and integrity, making it difficult to reproduce the actual behavior of rock masses controlled by numerous random fractures in engineering sites. Field tests, on the other hand, are costly and time-consuming. Especially for projects such as reservoir bank slopes, the periodic wet-dry cycles caused by reservoir water fluctuations continuously deteriorate the mechanical and creep properties of fractures, further complicating parameter determination.

[0003] The mechanical properties of fractured rock masses exhibit significant size effects: small-sized rock masses exhibit large property fluctuations, gradually stabilizing as their size increases. The creep characterization unit, or REV, represents the critical size at which rock mass properties transition from fluctuation to stability. Numerical simulation, due to its flexibility and repeatability, has become an important tool for studying REV. However, existing research largely focuses on REV for the geometric, instantaneous mechanical, and hydraulic parameters of rock masses, while creep characterization units (CREV) for their long-term deformation characteristics remain lacking. This results in a lack of equivalent creep parameters that can reasonably reflect the time-dependent evolution of fractured rock masses when analyzing long-term effects such as reservoir water fluctuations, making it difficult to effectively predict long-term engineering deformation.

[0004] Therefore, there is an urgent need to develop a method for determining the equivalent creep parameters of fractured rock masses that can comprehensively consider fracture networks and size effects. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a method, medium, and equipment for determining creep parameters of fractured rock masses based on the equivalent medium theory.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for determining creep parameters of fractured rock masses based on equivalent medium theory includes the following steps: Obtain the structural geometric parameters of the rock mass in the target engineering area, construct a stochastic fracture network model of fractured rock mass containing multiple sets of structural surfaces based on stochastic statistical methods, and generate numerical models of fractured rock mass of different sizes. By utilizing the secondary development interface of the discrete element numerical calculation software, the viscoelastic-plastic constitutive model of the structural surface is embedded into the discrete element numerical calculation software. Constant loads were applied to numerical models of fractured rock masses of different sizes, and numerical tests on the creep of fractured rock masses were carried out to obtain the creep deformation time history curves of each numerical model of fractured rock masses. The creep curves of fractured rock mass models of different sizes were parametrically inverted, and the stability of creep parameters as the size of the numerical model of the fractured rock mass was analyzed under different spatial orientations and different fracture development conditions. The size range of the CREV (creep characterization unit) of the fractured rock mass was determined. Under the determined CREV size, the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass are obtained; The obtained equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters were applied to the long-term deformation simulation of rock slope engineering, and were used to evaluate the long-term creep and stability of rock mass based on equivalent continuous media.

[0007] Furthermore, the random fracture network model of the fractured rock mass is constructed by statistically analyzing the dip angle, trace length, and spacing parameters of the structural surfaces to reflect the spatial distribution characteristics of the actual rock mass structural surfaces.

[0008] Furthermore, the viscoelastic-plastic constitutive model of the structural surface is a viscoelastic creep model.

[0009] Furthermore, the viscoelastic creep model is the Nishihara creep model, which is divided into viscoplastic and viscoelastic bodies to describe the mechanical behavior of the structural surface in the elastic deformation stage and the plastic deformation stage, respectively. When the structural surface is in an elastic state, that is, when the contact force f Less than yield strength f s ( f < f s When the tangential force is applied, the viscoplastic body does not deform. f＇ The expression is: , in, X and Y They are represented as follows: , ; When the structural surface enters the plastic stage, that is, when the contact force... f Not less than yield strength f s ( f ≥ f s When the tangential force occurs, the Hooke body, Kelvin body, and viscoplastic body all deform, and the tangential force... f＇ The expression is: , in, X＇ and Y＇ They are represented as follows: , ; In the formula, u＇ and u 0 These represent the displacements at the new time step and the old time step, respectively. E M This represents the elastic modulus of a Maxwell body. E k This represents the elastic modulus of the Kelvin body. η k This represents the viscosity coefficient of Kelvin volume. η p The viscosity coefficient of the viscoplastic material is represented by Δt, which represents the time step. f 0 Indicates the contact force in the previous step. This indicates the displacement of the Kelvin body at the previous time step.

[0010] The tangential force on the structural surface is calculated according to the Nishihara model. Its displacement increment is the sum of the displacements of the Hooke body, the Kelvin body, and the viscoplastic body. When the structural surface is in an elastic state, i.e., when the contact force is less than the yield strength, the viscoplastic body does not deform. In this case, the Nishihara model degenerates into the generalized Kelvin model, and the total displacement increment consists of two parts: the displacement increment of the Hooke body and the displacement increment of the Kelvin body. , In the formula, u 1 and u 2 These represent the displacements of the Hooke body and the Kelvin body, respectively, with the superscripts ' and 0 indicating the calculated values ​​at the current and previous time steps, respectively.

[0011] Furthermore, the numerical test of creep in the fractured rock mass is a uniaxial compression creep test.

[0012] Furthermore, when the creep parameters of the fractured rock mass tend to stabilize as the size of the numerical model of the fractured rock mass changes, the corresponding size of the numerical model of the fractured rock mass is determined as the size of the CREV (Crew Characterization Unit) of the fractured rock mass.

[0013] Furthermore, by changing the spatial orientation of the numerical model of the fractured rock mass, creep response curves in different directions are obtained to analyze the directional differences in the creep parameters of the fractured rock mass, and thereby determine the stability of the CREV (creep characterization unit) of the fractured rock mass.

[0014] Furthermore, multiple sets of numerical models of fractured rock masses were constructed based on different degrees of fracture development. By comparing and analyzing the variation of creep parameters with the size of the numerical models of fractured rock masses under different fracture development conditions, the size range of the CREV (creep characterization unit) of fractured rock masses was determined.

[0015] A computer-readable storage medium comprising a stored program that, when executed by a processor, implements the method for determining creep parameters of fractured rock mass based on equivalent medium theory as described above.

[0016] An electronic device, characterized in that the electronic device includes at least one processor and at least one memory connected to the processor; wherein the processor is used to call program instructions in the memory to execute the method for determining the creep parameters of fractured rock mass based on the equivalent medium theory as described above.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: 1. This method for determining creep parameters of fractured rock masses based on equivalent medium theory effectively solves the problem of lack of calculation basis for this key parameter through the above-mentioned steps, thus providing a more reliable theoretical basis for long-term stability assessment and safety prediction of hydropower, mining, tunnel and other projects, filling the gap in existing technologies in this regard; 2. This method integrates and improves existing theories and methods, equivalentizes complex fracture networks in theoretical models, and extracts key influencing parameters. While overcoming the limitations of traditional homogeneous assumptions, it integrates the advantages of equivalent medium theory and creep constitutive relations, and innovatively establishes a set of efficient and reasonable parameter determination models; 3. This method also has the advantages of simple logic and low computational workload. The calculation steps provided are concise and clear, and the calculation parameters involved can be directly obtained or measured by conventional on-site equipment, greatly reducing the implementation threshold. At the same time, the calculation process is clear, the results are accurate and repeatable, and it is easy to quickly promote and apply in actual engineering, providing direct support for related design and analysis. It has high practical value and promotion value in the field of rock engineering technology. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the process of embedding the Nishihara creep model into the discrete element numerical calculation software of this invention. Figure 2 This is a fracture network model diagram of the three types of rock masses in this invention; Figure 3 This is a schematic diagram showing the dimensions and rotation angles of the random fracture network model for fractured rock mass of the present invention; Figure 4 For the present invention E M , E K , η K A schematic diagram showing the relationship between stable strain and model side length; Figure 5 This is a schematic diagram showing the anisotropy of creep parameters and stable strain of rock masses of various sizes according to the present invention; Figure 6 For the present invention η P A schematic diagram showing the relationship between the rate of change of difference and the side length of the model; Figure 7 For rock masses of various sizes in this invention η P Anisotropy diagram; Figure 8 (a) and (b) are the FLAC3D models of PD66 numerical simulation, and (c) are the field detection results and simulation results of in-situ creep tests conducted at the monitoring points under pressures of 1 MPa and 2 MPa. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] A method for determining creep parameters of fractured rock masses based on equivalent medium theory includes the following steps: Step 1: Obtain the structural geometric parameters of the rock mass in the target engineering area, construct a stochastic fracture network model of fractured rock mass containing multiple sets of structural planes based on stochastic statistical methods, and generate numerical models of fractured rock mass of different sizes. Step 2: Using the secondary development interface of the discrete element numerical calculation software, embed the viscoelastic-plastic constitutive model of the structural surface into the discrete element numerical calculation software; Step 3: Apply constant load to the numerical models of fractured rock masses of different sizes, conduct numerical tests on the creep of fractured rock masses, and obtain the creep deformation time history curves of each numerical model of fractured rock masses. Step 4: Perform parameter inversion on the creep curves of fractured rock mass models of different sizes, and analyze the stability of creep parameters as the size of the fractured rock mass numerical model changes under different spatial orientations and different fracture development conditions, and determine the size range of the CREV (creep characterization unit) of the fractured rock mass. Step 5: Under the determined CREV dimensions, obtain the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass; Step 6: Apply the obtained equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters to the long-term deformation simulation of rock slope engineering, for the evaluation of long-term creep and stability of rock mass based on equivalent continuous medium.

[0021] In step 1, the random fracture network model of the fractured rock mass is constructed by statistically analyzing the dip angle, trace length, and spacing parameters of the structural surfaces to reflect the spatial distribution characteristics of the actual rock mass structural surfaces.

[0022] In step 2, the viscoelastic-plastic constitutive model of the structural surface is a viscoelastic creep model, preferably the Nishihara creep model. The Nishihara creep model is divided into viscoplastic body and viscoelastic body, which are used to describe the mechanical behavior of the structural surface in the elastic deformation stage and the plastic deformation stage, respectively.

[0023] In step 3, the numerical test of creep in the fractured rock mass is a uniaxial compression creep test.

[0024] In step 4, when the creep parameters of the fractured rock mass tend to stabilize as the size of the numerical model of the fractured rock mass changes, the corresponding size of the numerical model of the fractured rock mass is determined as the size of the CREV (Crew Characterization Unit) of the fractured rock mass.

[0025] In step 4, by changing the spatial orientation of the numerical model of the fractured rock mass, creep response curves in different directions are obtained to analyze the directional differences of the creep parameters of the fractured rock mass, and thereby determine the stability of the CREV of the creep characterization unit of the fractured rock mass.

[0026] In step 4, multiple sets of numerical models of fractured rock masses are constructed based on different degrees of fracture development. By comparing and analyzing the variation of creep parameters with the size of the numerical models of fractured rock masses under different fracture development conditions, the size range of the CREV (creep characterization unit) of fractured rock masses is determined.

[0027] This method for determining creep parameters in fractured rock masses based on the equivalent medium theory effectively solves the problem of lacking calculation basis for this key parameter through the above steps. This provides a more reliable theoretical basis for long-term stability assessment and safety prediction of hydropower, mining, tunnel and other projects, filling the gap in existing technology in this area.

[0028] This method integrates and improves existing theories and methods, equivalentizes complex fracture networks in theoretical models, and extracts key influencing parameters. While overcoming the limitations of the traditional homogeneous assumption, it integrates the advantages of equivalent medium theory and creep constitutive relations, and innovatively establishes a set of efficient and reasonable parameter determination models.

[0029] This method also boasts advantages such as simple logic and minimal computational workload. The provided calculation steps are concise and clear, and all calculation parameters involved can be directly obtained or measured using conventional on-site equipment, greatly lowering the implementation threshold. Furthermore, the calculation process is well-defined, the results are highly accurate and repeatable, facilitating rapid application in practical engineering projects and providing direct support for related design and analysis. It possesses high practical and promotional value in the field of rock engineering technology.

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below in conjunction with the accompanying drawings and Embodiment 1.

[0031] Example 1: Taking the left bank slope project of a certain hydropower station as an example.

[0032] (1) Establish a viscoelastic-plastic creep constitutive model for the structural surface, wherein the creep constitutive model is the Nishihara creep model (e.g., Figure 1 (As shown). In the Nishihara creep model, the structural surface is divided into viscoelastic elements and viscoplastic elements to describe the creep mechanical behavior of the structural surface in the elastic deformation stage and the plastic deformation stage, respectively.

[0033] Using the secondary development interface of the discrete element numerical calculation software UDEC, the viscoelastic-plastic constitutive model of the structural surface is embedded into the software. The embedding process is described in [link to embedding procedure]. Figure 1 This enables the fractured rock mass model to simulate the creep deformation process of structural surfaces under long-term loads.

[0034] Combination Figure 1 As shown, the embedding process includes at least the following steps: Input material parameters and read the contact force, displacement, and displacement increment of the previous time step; Obtain the time step Δt, and calculate the normal force at the current time step according to the elastic calculation method; Determine contact force f Is it greater than or equal to the yield strength? f s ; If yes, calculate the tangential force at the current time step according to elastic-viscosity; otherwise, calculate the tangential force at the current time step according to plasticity. Return the calculated tangential and normal forces, and calculate the displacement and displacement increment; Then, the equilibrium is calculated to determine whether the creep time has been reached. If so, the calculation ends; otherwise, the process returns to the step of inputting material parameters.

[0035] When the structural surface is in an elastic state, that is, when the contact force f Less than yield strength f s ( f < f sWhen the tangential force is applied, the viscoplastic body does not deform. f＇ The expression is: , in, , ; When the structural surface enters the plastic stage, that is, when the contact force... f Not less than yield strength f s ( f ≥ f s When the tangential force occurs, the Hooke body, Kelvin body, and viscoplastic body all deform, and the tangential force... f＇ The expression is: , in, , ; In the formula, u＇ and u 0 These represent the displacements at the new time step and the old time step, respectively. E M This represents the elastic modulus of a Maxwell body. E k This represents the elastic modulus of the Kelvin body. η k This represents the viscosity coefficient of Kelvin volume. η p The viscosity coefficient of the viscoplastic material is represented by Δt, which represents the time step. f 0 Indicates the contact force in the previous step. This indicates the displacement of the Kelvin body at the previous time step.

[0036] (2) Obtain the geometric parameters of the structural planes in the rock mass of the target engineering area, including the dip angle, trace length and spacing of the structural planes, and perform statistical analysis on the geometric parameters of the structural planes. Based on the statistical results, the rock mass of the research object is divided into three types of rock mass with different degrees of fracture development: Class III, Class IV1 and Class IV2. The statistical results of the geometric parameters of the structural planes corresponding to the three types of rock mass are shown in Table 1.

[0037] Table 1: Geometric parameters of structural planes in three rock mass calculation models

[0038] Based on the aforementioned structural surface geometric parameters, a stochastic fracture network model of fractured rock mass containing multiple sets of structural surfaces is constructed using a stochastic statistical method to reflect the spatial distribution characteristics of actual rock mass structural surfaces. Typical fracture network models corresponding to the three rock mass types are shown below. Figure 2 As shown in the figure. Furthermore, multiple numerical models of fractured rock masses of different sizes were generated for subsequent analysis of the creep characteristics of fractured rock masses.

[0039] (3) Numerical tests on the creep of fractured rock masses were carried out for the different sizes of fractured rock masses generated in (2) to reflect the spatial distribution characteristics of the actual rock mass structure.

[0040] In this embodiment, the numerical creep test of the fractured rock mass adopts the uniaxial compression creep test method, and the creep deformation time history curves of each fractured rock mass model are obtained by calculation. The relevant parameter values ​​of the rock block and structural surface are shown in Table 2.

[0041] Table 2: Parameter Values ​​for Rock Blocks and Structural Surfaces

[0042] During implementation, by changing the spatial orientation of the fractured rock mass model, creep response curves in different directions were obtained. These curves were used to analyze the directional differences in the creep characteristics of the fractured rock mass, thereby characterizing the anisotropic features of the creep behavior of the fractured rock mass. The dimensions and rotation angles of the fracture network model are as follows: Figure 3 As shown, by comparing the creep response curves of fractured rock masses under different rotation directions, the directional differences in the creep characteristics of fractured rock masses can be analyzed, thereby characterizing the anisotropic characteristics of the creep behavior of fractured rock masses.

[0043] (4) Based on the creep deformation time history curves of fractured rock mass models of different sizes obtained in (3), the creep parameters of the fractured rock mass are inverted and calculated. By comparing and analyzing the creep parameters with the model size under different degrees of fracture development, different sizes, and different rotation angles, when the creep parameters tend to be stable with the model size under various conditions, the corresponding model size is determined as the size range of the CREV characterization unit of the fractured rock mass. Based on the creep deformation time history curves of fractured rock mass models of different sizes obtained in step (3), the viscoelastic creep parameters and viscoplastic creep parameters of the fractured rock mass are inverted and calculated.

[0044] By studying the viscoelastic creep parameters of fractured rock masses under different model size conditions E M , E K , η K The analysis of the variation of stable strain with the side length of the model is as follows: Figure 4 As shown.

[0045] Further comparative analysis was conducted on the creep parameters of fractured rock masses of different sizes under different rotational directions to reveal the anisotropic characteristics of creep parameters and stability strain of fractured rock masses. The results are as follows: Figure 5 As shown, based on the variation law of creep parameters under different rotation directions, the relationship between the representative volume element REV of viscoelastic creep parameters and stable strain of fractured rock mass and the rotation direction is obtained.

[0046] Meanwhile, the viscoplastic creep parameters of fractured rock mass η P Perform inversion analysis to obtain η P The relationship between the rate of change of variation and the side length of the model, such as Figure 6 As shown, rock masses with fractures of different sizes are further analyzed. η P The anisotropic characteristics, such as Figure 7 As shown.

[0047] By comprehensively comparing and analyzing the stability of creep parameters with model size under different degrees of fracture development, different sizes, and different rotation angles, when the creep parameters tend to be stable with model size under multiple conditions, the corresponding model size is determined as the size of the CREV (Crew Characterization Unit) of fractured rock mass, i.e., 6.0m.

[0048] (5) Within the determined CREV size range, obtain the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass. Based on the equivalent creep parameters, establish an equivalent continuous medium creep model of the fractured rock mass to describe the long-term creep deformation behavior of the fractured rock mass at the engineering scale.

[0049] The viscoelastic-plastic models of the three types of rock masses were calculated, and their equivalent creep parameters are shown in Table 3.

[0050] Table 3: Equivalent creep parameters of three types of rock masses

[0051] (6) The obtained equivalent creep parameters are applied to engineering-scale numerical analysis and compared with the results of in-situ internal and surface creep monitoring. The simulation results of the point PD66 used in FLAC3D are as follows: Figure 8 (a) and Figure 8 As shown in (b), the in-situ creep test results of the exploration tunnel under pressure conditions of 1 MPa and 2 MPa are as follows: Figure 8 As shown in (c). The results show that the creep curves obtained by numerical simulation are in high agreement with the in-situ test results, verifying that the determined equivalent creep parameters are suitable for simulating the long-term deformation behavior of fractured rock masses.

[0052] Example 2: A medium is provided, which is a computer-readable storage medium, the computer-readable storage medium including a stored program, which, when executed by a processor, implements the method for determining the creep parameters of fractured rock mass based on the equivalent medium theory as described above.

[0053] An electronic device is also provided, comprising at least one processor and at least one memory connected to the processor; wherein the processor is configured to call program instructions in the memory to execute the method for determining the creep parameters of fractured rock mass based on the equivalent medium theory as described above.

[0054] The steps to be performed are as follows: Step 1: Obtain the structural geometric parameters of the rock mass in the target engineering area, construct a stochastic fracture network model of fractured rock mass containing multiple sets of structural planes based on stochastic statistical methods, and generate numerical models of fractured rock mass of different sizes. The random fracture network model of fractured rock mass is constructed by statistically analyzing the dip angle, trace length, and spacing parameters of structural surfaces to reflect the spatial distribution characteristics of actual rock mass structural surfaces. Step 2: Using the secondary development interface of the discrete element numerical calculation software, embed the viscoelastic-plastic constitutive model of the structural surface into the discrete element numerical calculation software; The viscoelastic-plastic constitutive model of the structural surface is the Nishihara creep model, which is divided into viscoplastic body and viscoelastic body to describe the mechanical behavior of the structural surface in the elastic deformation stage and the plastic deformation stage, respectively. Step 3: Apply constant load to the numerical models of fractured rock masses of different sizes, conduct numerical tests on the creep of fractured rock masses, and obtain the creep deformation time history curves of each numerical model of fractured rock masses. Step 4: Perform parameter inversion on the creep curves of fractured rock mass models of different sizes, and analyze the stability of creep parameters as the size of the fractured rock mass numerical model changes under different spatial orientations and different fracture development conditions, and determine the size range of the CREV (creep characterization unit) of the fractured rock mass. When the creep parameters of the fractured rock mass tend to stabilize as the size of the numerical model of the fractured rock mass changes, the corresponding size of the numerical model of the fractured rock mass is determined as the size of the CREV (creep characterization unit) of the fractured rock mass. By changing the spatial orientation of the numerical model of the fractured rock mass, creep response curves in different directions are obtained to analyze the directional differences of creep parameters in the fractured rock mass, and to determine the stability of the CREV of the creep characterization unit of the fractured rock mass. Multiple sets of numerical models of fractured rock masses were constructed based on different degrees of fracture development. By comparing and analyzing the law of creep parameter variation with the size of the numerical model of fractured rock mass under different fracture development conditions, the size range of the creep characterization unit CREV of fractured rock mass was determined. Step 5: Under the determined CREV dimensions, obtain the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass; Step 6: Apply the obtained equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters to the long-term deformation simulation of rock slope engineering.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for determining creep parameters of fractured rock masses based on equivalent medium theory, characterized in that, Includes the following steps: Obtain the structural geometric parameters of the rock mass in the target engineering area, construct a stochastic fracture network model of fractured rock mass containing multiple sets of structural surfaces based on stochastic statistical methods, and generate numerical models of fractured rock mass of different sizes. By utilizing the secondary development interface of the discrete element numerical calculation software, the viscoelastic-plastic constitutive model of the structural surface is embedded into the discrete element numerical calculation software. Constant loads were applied to numerical models of fractured rock masses of different sizes, and numerical tests on the creep of fractured rock masses were carried out to obtain the creep deformation time history curves of each numerical model of fractured rock masses. The creep curves of fractured rock mass models of different sizes were parametrically inverted, and the stability of creep parameters as the size of the numerical model of the fractured rock mass was analyzed under different spatial orientations and different fracture development conditions. The size range of the CREV (creep characterization unit) of the fractured rock mass was determined. Under the determined CREV size, the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass are obtained; The obtained equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters were applied to the long-term deformation simulation of rock slope engineering, and were used to evaluate the long-term creep and stability of rock mass based on equivalent continuous media.

2. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, The random fracture network model of fractured rock mass is constructed by statistically analyzing the dip angle, trace length, and spacing parameters of structural surfaces to reflect the spatial distribution characteristics of actual rock mass structural surfaces.

3. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, The viscoelastic-plastic constitutive model of the structural surface is a viscoelastic creep model.

4. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 3, characterized in that, The viscoelastic creep model selected is the Nishihara creep model, which is divided into viscoplastic and viscoelastic bodies to describe the mechanical behavior of the structural surface in the elastic deformation stage and the plastic deformation stage, respectively. When the structural surface is in an elastic state, that is, when the contact force f Less than yield strength f s At this time, the viscoplastic body does not deform, and the tangential force... f＇ The expression is: ， in, X and Y They are represented as follows: ， ； When the structural surface enters the plastic stage, that is, when the contact force... f Not less than yield strength f s At that time, the Hooke body, Kelvin body, and viscoplastic body all deformed, and the tangential force... f＇ The expression is: ， in, X＇ and Y＇ They are represented as follows: ， ； In the formula, u' and u 0 These represent the displacements at the new time step and the old time step, respectively. E M This represents the elastic modulus of a Maxwell body. E k This represents the elastic modulus of the Kelvin body. η k This represents the viscosity coefficient of Kelvin volume. η p The viscosity coefficient of the viscoplastic material is represented by Δt, which represents the time step. f 0 Indicates the contact force in the previous step. This indicates the displacement of the Kelvin body at the previous time step.

5. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, The numerical test of creep in the fractured rock mass was a uniaxial compression creep test.

6. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, When the creep parameters of the fractured rock mass tend to stabilize as the size of the numerical model of the fractured rock mass changes, the corresponding size of the numerical model of the fractured rock mass is determined as the size of the CREV (Crew Characterization Unit) of the fractured rock mass.

7. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, By changing the spatial orientation of the numerical model of the fractured rock mass, creep response curves in different directions are obtained to analyze the directional differences in creep parameters of the fractured rock mass, and to determine the stability of the CREV (creep response energy) of the fractured rock mass creep characterization unit.

8. The method for determining creep parameters of fractured rock mass based on equivalent medium theory according to claim 1, characterized in that, Multiple sets of numerical models of fractured rock masses were constructed based on different degrees of fracture development. By comparing and analyzing the variation of creep parameters with the size of the numerical models of fractured rock masses under different fracture development conditions, the size range of the creep characterization unit CREV of fractured rock masses was determined.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program that, when executed by a processor, implements the method for determining creep parameters of fractured rock mass based on the equivalent medium theory as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, The electronic device includes at least one processor and at least one memory connected to the processor; wherein the processor is used to call program instructions in the memory to execute the method for determining the creep parameters of fractured rock mass based on the equivalent medium theory as described in any one of claims 1 to 8.

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