A method and system for constructing a rock constitutive model

Abstract

The present invention provides a method and system for constructing a rock constitutive model, the method comprising: applying initial conditions and initial fitting parameter variables to the rock body according to actual mechanical results; iteratively updating the initial stress through stress increments to obtain updated predicted stress; obtaining elastic strain increments through initial conditions to update the initial elastic strain to predicted elastic strain; obtaining plastic strain increments through initial conditions to update the initial plastic strain to predicted plastic strain; obtaining predicted strains, comparing the final predicted stress and predicted strain with actual mechanical experimental results to obtain final fitting parameter variables, and constructing a final rock constitutive model. By distinguishing elastic deformation from plastic deformation, the evolution of elastic deformation and plastic deformation of the rock body under compression load can be accurately described, which is more in line with the actual deformation behavior of the rock body, thereby ensuring that subsequent predictions of complex rock behaviors are more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a method and system for constructing a rock constitutive model. Background Art

[0002] The rock constitutive model is a basic tool in rock engineering. Through this model, the deformation and failure behavior of rock under compressive load can be predicted, which provides the necessary basis for the numerical simulation of rock engineering, thereby helping engineers predict the mechanical behavior of rock under complex geological conditions. Accurate and reliable rock constitutive models play a vital role in the stability and disaster warning of rock engineering.

[0003] Generally speaking, the constitutive characteristics of rock include elastic deformation, plastic deformation, etc. The degree of realization of these factors determines the reliability of rock constitutive properties.

[0004] Traditional rock constitutive models are based on yield criteria, flow rules, and hardening or softening laws. They usually assume that the deformation of rock within the initial yield surface is purely elastic, which is different from the actual mechanical behavior of rock, and the relevant flow laws break the causal relationship between strain and stress. The rock constitutive model is constructed based on continuous damage mechanics and statistical methods to describe the damage process of rock through the distribution of damage variables, but there are still deficiencies in the three-dimensional strain of rock, especially the distinction between elastic deformation and plastic deformation. This will lead to certain errors in the model when predicting the complex deformation behavior of rock, and then lead to inaccurate prediction of the mechanical behavior of rock mass based on the constructed constitutive model. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method and system for constructing a rock constitutive model, aiming to solve the technical problem that the assumption of pure elastic behavior within the yield surface in the prior art is not accurate enough, or there are still deficiencies in the distinction between three-dimensional strain of rock, especially elastic deformation and plastic deformation, which will lead to certain errors in the model when predicting the complex deformation behavior of rock, and further lead to inaccurate prediction of the subsequent mechanical behavior of the rock mass.

[0006] In order to achieve the above objectives, in a first aspect, an embodiment of the present application provides a method for constructing a rock constitutive model, comprising the following steps:

[0007] Applying initial conditions to the rock body according to actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model;

[0008] Iteratively updating the initial stress by using the stress increment to obtain an updated predicted stress;

[0009] Obtaining an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and updating the initial elastic strain through the elastic strain increment to obtain a predicted elastic strain;

[0010] Obtaining the size and direction of the plastic strain increment by using the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and updating the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain;

[0011] The predicted strain is obtained based on the predicted elastic strain and the predicted plastic strain, the updated predicted stress and the predicted strain are compared with the actual mechanical experimental results to update the initial fitting parameter variables to final fitting parameter variables, and a final rock constitutive model is constructed based on the final fitting parameter variables.

[0012] Compared with the prior art, the beneficial effect of the present invention is that: by obtaining the predicted elastic strain and the predicted plastic strain, the elastic deformation and plastic deformation of the rock body are distinguished, and then the predicted strain, the updated predicted stress and the actual mechanical experimental results are compared to ensure that the final fitting parameter variables that are closer to the rock body are obtained, and then the construction of the final rock constitutive model is completed. Compared with the traditional constitutive model, the concept of traditional yield surface is abandoned, the improper assumption of the pure elastic deformation stage of rock and the limitation of the flow law that breaks the causal relationship between strain and stress are avoided, so that the obtained final rock constitutive model can accurately describe the evolution of elastic deformation and plastic deformation of the rock body under compression load, which is more in line with the actual deformation behavior of the rock body. On this basis, it can ensure that the prediction of complex rock behavior based on the final rock constitutive model is more accurate.

[0013] Furthermore, the initial fitting parameter variables include a first initial variable, a second initial variable, a third initial variable, a fourth initial variable, a fifth initial variable, a sixth initial variable, a seventh initial variable, an eighth initial variable and a ninth initial variable, and the actual mechanical experimental results include actual stress and actual strain.

[0014] Furthermore, the step of iteratively updating the initial stress by using the stress increment to obtain an updated predicted stress includes:

[0015] superimposing the stress increment and the initial stress to obtain an updated stress;

[0016] It is determined whether the updated stress is greater than the material peak stress; if the updated stress is greater than the material peak stress, the updated stress is determined to be the updated predicted stress.

[0017] Furthermore, the step of obtaining the elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable includes:

[0018] Determine the elastic modulus and Poisson's ratio of the rock body through the vector value of the initial plastic strain and the initial fitting parameter variable;

[0019] Obtaining a stiffness matrix based on the elastic modulus and the Poisson's ratio;

[0020] The elastic strain increment is obtained through the stiffness matrix and the stress increment.

[0021] Furthermore, the formula for obtaining the elastic modulus is:

[0022] ,

[0023] in, represents the elastic modulus, represents the first initial variable, represents the second initial variable, represents the third initial variable, The vector value representing the initial plastic strain;

[0024] The formula for obtaining the Poisson's ratio is:

[0025] ,

[0026] in, represents Poisson's ratio, represents the fourth initial variable, represents the fifth initial variable;

[0027] The expression of the stiffness matrix is:

[0028] ,

[0029] in, represents the stiffness matrix.

[0030] Furthermore, the step of obtaining the size and direction of the plastic strain increment by updating the predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable includes:

[0031] Obtaining equivalent stress based on a first stress component, a second stress component, and a third stress component of the updated predicted stress in a three-dimensional coordinate system, and determining an equivalent stress increment through the equivalent stress and a first stress increment component, a second stress increment component, and a third stress increment component of the stress increment in a three-dimensional coordinate system;

[0032] Obtaining the size of the plastic strain increment based on the sixth initial variable, the seventh initial variable, the vector value of the initial plastic strain and the equivalent stress increment;

[0033] The expansion angle is determined by the eighth initial variable, the ninth initial variable and the vector value of the initial plastic strain to obtain a conical surface corresponding to the plastic strain increment, and the direction of the plastic strain increment is determined by the coplanarity of the stress increment, the elastic strain increment and the plastic strain increment.

[0034] Furthermore, the formula for obtaining the equivalent stress increment is:

[0035] ,

[0036] in, represents the equivalent stress increment, represents the equivalent stress, represents the first stress component, represents the second stress component, represents the third stress component, represents the first stress increment component, represents the second stress increment component, represents the third stress increment component.

[0037] Furthermore, the step of comparing the updated predicted stress and the predicted strain with the actual mechanical test results to update the initial fitting parameter variables to final fitting parameter variables includes:

[0038] Comparing the predicted strain corresponding to the updated predicted stress and the actual stress at the same level with the actual strain to obtain a strain error;

[0039] Determining whether the strain error is less than a strain error threshold;

[0040] If the strain error is less than the strain error threshold, the initial fitting parameter variable is determined as the final fitting parameter variable.

[0041] In a second aspect, an embodiment of the present application provides a system for constructing a rock constitutive model, which is applied to the method for constructing a rock constitutive model as described in the first aspect above, and the system includes:

[0042] A prediction module is used to apply initial conditions to the rock body according to actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model;

[0043] A judgment module, used for iteratively updating the initial stress through the stress increment to obtain an updated predicted stress;

[0044] A first analysis module is used to obtain an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and the initial elastic strain is updated through the elastic strain increment to obtain a predicted elastic strain;

[0045] A second analysis module is used to obtain the size and direction of the plastic strain increment through the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and update the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain;

[0046] A construction module is used to obtain the predicted strain based on the predicted elastic strain and the predicted plastic strain, compare the updated predicted stress and the predicted strain with the actual mechanical experimental results to update the initial fitting parameter variables to the final fitting parameter variables, and construct a final rock constitutive model based on the final fitting parameter variables.

[0047] In a third aspect, an embodiment of the present application provides a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for constructing a rock constitutive model as described in the first aspect above is implemented.

[0048] In a fourth aspect, an embodiment of the present application provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for constructing a rock constitutive model as described in the first aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flow chart of the method for constructing a rock constitutive model in the first embodiment of the present invention;

[0050] Figure 2 is a structural block diagram of a system for constructing a rock constitutive model in a second embodiment of the present invention;

[0051] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0053] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0055] See also Figure 1 The method for constructing a rock constitutive model provided in the first embodiment of the present invention comprises the following steps:

[0056] S10: applying initial conditions to the rock body according to actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model;

[0057] In this embodiment, the rock body for the actual mechanical experiment is a granite block with a height of 100 mm and a diameter of 50 mm. By applying confining pressure and axial pressure, triaxial loading is completed on the rock body until the rock body is damaged, and the actual mechanical experiment results are obtained, which include actual stress and actual strain. Through the actual stress and the actual strain, the actual stress-strain curve of the rock body can be obtained.

[0058] The initial fitting parameter variables include a first initial variable, a second initial variable, a third initial variable, a fourth initial variable, a fifth initial variable, a sixth initial variable, a seventh initial variable, an eighth initial variable and a ninth initial variable. In the construction of a conventional constitutive model, it is necessary to determine the initial fitting parameter quantity, that is, nine variables are required, and the construction principle thereof will not be repeated here.

[0059] S20: iteratively updating the initial stress by using the stress increment to obtain an updated predicted stress;

[0060] The step S20 comprises:

[0061] S210: superimposing the stress increment and the initial stress into an updated stress;

[0062] S220: Determine whether the updated stress is greater than the material peak stress; if the updated stress is greater than the material peak stress, determine the updated stress as the updated predicted stress.

[0063] If the updated stress is less than the material peak stress, the stress increment is superimposed on the updated stress again, that is, the stress increment is iteratively increased on the basis of the initial stress. It should be noted that the stress increment is a fixed value. Assuming that the initial stress is 0Pa and the stress increment is 5Pa, after one superposition, the updated stress is 5Pa, and after another superposition, the updated stress is 10Pa.

[0064] S30: obtaining an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and updating the initial elastic strain through the elastic strain increment to obtain a predicted elastic strain;

[0065] The step S30 comprises:

[0066] S310: determining the elastic modulus and Poisson's ratio of the rock body through the vector value of the initial plastic strain and the initial fitting parameter variable;

[0067] The formula for obtaining the elastic modulus is:

[0068] ,

[0069] in, represents the elastic modulus, represents the first initial variable, represents the second initial variable, represents the third initial variable, The vector value representing the initial plastic strain;

[0070] The formula for obtaining the Poisson's ratio is:

[0071] ,

[0072] in, represents Poisson's ratio, represents the fourth initial variable, Represents the fifth initial variable.

[0073] S320: Acquire a stiffness matrix based on the elastic modulus and the Poisson's ratio;

[0074] The expression of the stiffness matrix is:

[0075] ,

[0076] in, represents the stiffness matrix.

[0077] S330: Obtaining an elastic strain increment through the stiffness matrix and the stress increment;

[0078] The relationship between the stress increment and the elastic strain increment is:

[0079] ,

[0080] in, Represents the first stress increment component of the stress increment in the three-dimensional coordinate system, The second stress increment component representing the stress increment in the three-dimensional coordinate system, Represents the third stress increment component of the stress increment in the three-dimensional coordinate system, Represents the first elastic strain increment component of the elastic strain increment in the three-dimensional coordinate system, Represents the second elastic strain increment component of the elastic strain increment in the three-dimensional coordinate system, Represents the third elastic strain increment component of the elastic strain increment in the three-dimensional coordinate system.

[0081] The predicted elastic strain is obtained by superimposing the elastic strain increment with the initial elastic strain. It should be noted that the predicted elastic strain can be formed by iteratively superimposing the initial elastic strain with the elastic strain increment.

[0082] S40: obtaining the size and direction of the plastic strain increment by using the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and updating the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain;

[0083] The step S40 comprises:

[0084] S410: Obtaining an equivalent stress based on a first stress component, a second stress component, and a third stress component of the updated predicted stress in a three-dimensional coordinate system, and determining an equivalent stress increment through the equivalent stress and a first stress increment component, a second stress increment component, and a third stress increment component of the stress increment in a three-dimensional coordinate system;

[0085] The calculation formula of the equivalent stress is:

[0086] ,

[0087] in, represents the equivalent stress, represents the first stress component, represents the second stress component, represents the third stress component.

[0088] The formula for obtaining the equivalent stress increment is:

[0089] ,

[0090] in, represents the equivalent stress increment, represents the equivalent stress, represents the first stress component, represents the second stress component, represents the third stress component, represents the first stress increment component, represents the second stress increment component, represents the third stress increment component.

[0091] S420: Obtaining a size of a plastic strain increment based on the sixth initial variable, the seventh initial variable, the vector value of the initial plastic strain, and the equivalent stress increment;

[0092] The formula for obtaining the size of the plastic strain increment is:

[0093] ,

[0094] in, represents the size of the plastic strain increment, represents the peak stress of the material, represents the sixth initial variable, represents the seventh initial variable, represents the exponential function, represents the vector value of the initial plastic strain, Represents the equivalent stress increment.

[0095] S430: Determine the expansion angle through the eighth initial variable, the ninth initial variable and the vector value of the initial plastic strain to obtain a conical surface corresponding to the plastic strain increment, and determine the direction of the plastic strain increment through the coplanarity of the stress increment, the elastic strain increment and the plastic strain increment.

[0096] The formula for obtaining the expansion angle is:

[0097] ,

[0098] in, represents the expansion angle, represents the eighth initial variable, Represents the ninth initial variable.

[0099] By obtaining the expansion angle, the pressure point can be taken as the axis to expand to form a conical surface. It can be understood that the elastic strain increment also corresponds to a conical surface, and the angles of the two conical surfaces are different.

[0100] It should be noted that the initial plastic strain may be iteratively superimposed via the plastic strain increment to form the predicted plastic strain.

[0101] S50: obtaining predicted strain based on the predicted elastic strain and the predicted plastic strain, comparing the updated predicted stress and the predicted strain with the actual mechanical test results to update the initial fitting parameter variables to final fitting parameter variables, and constructing a final rock constitutive model based on the final fitting parameter variables;

[0102] The updated predicted stress and the predicted strain may also form a predicted stress-strain curve.

[0103] The step S50 comprises:

[0104] S510: comparing the predicted strain corresponding to the updated predicted stress and the actual stress at the same level with the actual strain to obtain a strain error;

[0105] It should be noted that the same level means that in the actual stress-strain curve and the predicted stress-strain curve, the updated predicted stress and the actual stress have the same value. When the updated predicted stress and the actual stress have the same value, the strain error is formed between the predicted strain and the actual strain respectively corresponding to them.

[0106] S520: Determine whether the strain error is less than a strain error threshold;

[0107] S530: If the strain error is less than the strain error threshold, determining the initial fitting parameter variable as the final fitting parameter variable;

[0108] If the strain error is greater than the strain error threshold, the initial fitting parameter variables are updated by a genetic algorithm. Specifically, the initial fitting parameter variables are encoded into a format used in a genetic algorithm, the actual stress-strain curve is compared with the predicted stress-strain curve, and the sum of squares of strain errors at each point is calculated to obtain target values ​​of several fitness functions, and the minimum value is selected from the target values ​​of several fitness functions to obtain the optimal fitness individual, and the optimal fitness individual is substituted into the next generation, and the selected individuals are cross-operated to generate a new generation of individuals, the genetic information of the parent generation is mixed, the diversity of the population is increased, and the population is gradually purified through multiple generations of iterations, and finally the parameter combination with the highest fitness is obtained, that is, the final fitting parameter variables. By introducing a genetic algorithm to update the initial fitting parameter variables, the final fitting parameter variables can be quickly obtained by relying only on monotonically loaded data, which significantly reduces the complexity of experiments and calculations and improves the efficiency of building the final rock constitutive model.

[0109] By obtaining the predicted elastic strain and the predicted plastic strain, the elastic deformation and plastic deformation of the rock body are distinguished, and then the predicted strain, the updated predicted stress and the actual mechanical experimental results are compared to ensure that the final fitting parameter variables that are closer to the rock body are obtained, and then the construction of the final rock constitutive model is completed. Compared with the traditional constitutive model, the concept of traditional yield surface is abandoned, the improper assumption of the pure elastic deformation stage of rock and the limitation of the flow law that breaks the causal relationship between strain and stress are avoided, so that the obtained final rock constitutive model can accurately describe the evolution of elastic deformation and plastic deformation of the rock body under compression load, which is more in line with the actual deformation behavior of the rock body. On this basis, it can ensure that the prediction of complex rock behavior based on the final rock constitutive model is more accurate.

[0110] See also Figure 2 The second embodiment of the present invention provides a system for constructing a rock constitutive model, which is applied to the method for constructing a rock constitutive model in the above-mentioned embodiment, and will not be repeated here. As used below, the terms "module", "unit", "subunit", etc. can be a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, the implementation in hardware, or a combination of software and hardware, is also possible and conceivable.

[0111] The system comprises:

[0112] The prediction module 10 is used to apply initial conditions to the rock body according to the actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model;

[0113] A judgment module 20, configured to iteratively update the initial stress by using the stress increment to obtain an updated predicted stress;

[0114] The judging module 20 comprises:

[0115] A first unit is used for superimposing the stress increment and the initial stress into an updated stress;

[0116] The second unit is used to determine whether the updated stress is greater than the material peak stress, and if the updated stress is greater than the material peak stress, the updated stress is determined as the updated predicted stress;

[0117] A first analysis module 30 is used to obtain an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and the initial elastic strain is updated through the elastic strain increment to obtain a predicted elastic strain;

[0118] The first analysis module 30 includes:

[0119] The third unit is used to determine the elastic modulus and Poisson's ratio of the rock body through the vector value of the initial plastic strain and the initial fitting parameter variable;

[0120] A fourth unit is used to obtain a stiffness matrix based on the elastic modulus and the Poisson's ratio;

[0121] A fifth unit, used for obtaining an elastic strain increment through the stiffness matrix and the stress increment;

[0122] A second analysis module 40 is used to obtain the size and direction of the plastic strain increment through the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and update the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain;

[0123] The second analysis module 40 includes:

[0124] A sixth unit is used to obtain an equivalent stress based on the first stress component, the second stress component and the third stress component of the updated predicted stress in the three-dimensional coordinate system, and determine an equivalent stress increment through the equivalent stress and the first stress increment component, the second stress increment component and the third stress increment component of the stress increment in the three-dimensional coordinate system;

[0125] A seventh unit, used for obtaining the size of the plastic strain increment based on the sixth initial variable, the seventh initial variable, the vector value of the initial plastic strain and the equivalent stress increment;

[0126] an eighth unit, configured to determine an expansion angle by using the eighth initial variable, the ninth initial variable and the vector value of the initial plastic strain to obtain a conical surface corresponding to the plastic strain increment, and determine a direction of the plastic strain increment by using the coplanarity of the stress increment, the elastic strain increment and the plastic strain increment;

[0127] A construction module 50 is used to obtain a predicted strain based on the predicted elastic strain and the predicted plastic strain, compare the updated predicted stress and the predicted strain with the actual mechanical test results to update the initial fitting parameter variables to final fitting parameter variables, and construct a final rock constitutive model based on the final fitting parameter variables;

[0128] The building block 50 comprises:

[0129] A ninth unit is used for comparing the predicted strain corresponding to the updated predicted stress and the actual stress at the same level with the actual strain to obtain a strain error;

[0130] A tenth unit, used for judging whether the strain error is less than a strain error threshold;

[0131] The eleventh unit is configured to determine the initial fitting parameter variable as the final fitting parameter variable if the strain error is less than the strain error threshold.

[0132] The present invention also provides a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for constructing a rock constitutive model as described in the above technical solution is implemented.

[0133] The present invention also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the method for constructing a rock constitutive model as described in the above technical solution is implemented.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for constructing a rock constitutive model, characterized in that: The following steps are involved: Applying initial conditions to the rock body according to actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model; Iteratively updating the initial stress by using the stress increment to obtain an updated predicted stress; Obtaining an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and updating the initial elastic strain through the elastic strain increment to obtain a predicted elastic strain; Obtaining the size and direction of the plastic strain increment by using the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and updating the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain; The predicted strain is obtained based on the predicted elastic strain and the predicted plastic strain, the updated predicted stress and the predicted strain are compared with the actual mechanical experimental results to update the initial fitting parameter variables to final fitting parameter variables, and a final rock constitutive model is constructed based on the final fitting parameter variables.

2. The method for constructing a rock constitutive model according to claim 1, characterized in that: The initial fitting parameter variables include a first initial variable, a second initial variable, a third initial variable, a fourth initial variable, a fifth initial variable, a sixth initial variable, a seventh initial variable, an eighth initial variable and a ninth initial variable, and the actual mechanical experimental results include actual stress and actual strain.

3. The method for constructing a rock constitutive model according to claim 2, characterized in that: The step of iteratively updating the initial stress by using the stress increment to obtain an updated predicted stress comprises: superimposing the stress increment and the initial stress to obtain an updated stress; It is determined whether the updated stress is greater than the material peak stress; if the updated stress is greater than the material peak stress, the updated stress is determined to be the updated predicted stress.

4. The method for constructing a rock constitutive model according to claim 3, characterized in that: The step of obtaining the elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable comprises: Determine the elastic modulus and Poisson's ratio of the rock body through the vector value of the initial plastic strain and the initial fitting parameter variable; Obtaining a stiffness matrix based on the elastic modulus and the Poisson's ratio; The elastic strain increment is obtained through the stiffness matrix and the stress increment.

5. The method for constructing a rock constitutive model according to claim 4, characterized in that: The formula for obtaining the elastic modulus is: ， in, represents the elastic modulus, represents the first initial variable, represents the second initial variable, represents the third initial variable, The vector value representing the initial plastic strain; The formula for obtaining the Poisson's ratio is: ， in, represents Poisson's ratio, represents the fourth initial variable, represents the fifth initial variable; The expression of the stiffness matrix is: ， in, represents the stiffness matrix.

6. The method for constructing a rock constitutive model according to claim 3, characterized in that: The step of obtaining the size and direction of the plastic strain increment by using the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable comprises: Obtaining equivalent stress based on a first stress component, a second stress component, and a third stress component of the updated predicted stress in a three-dimensional coordinate system, and determining an equivalent stress increment through the equivalent stress and a first stress increment component, a second stress increment component, and a third stress increment component of the stress increment in a three-dimensional coordinate system; Obtaining the size of the plastic strain increment based on the sixth initial variable, the seventh initial variable, the vector value of the initial plastic strain and the equivalent stress increment; The expansion angle is determined by the eighth initial variable, the ninth initial variable and the vector value of the initial plastic strain to obtain a conical surface corresponding to the plastic strain increment, and the direction of the plastic strain increment is determined by the coplanarity of the stress increment, the elastic strain increment and the plastic strain increment.

7. The method for constructing a rock constitutive model according to claim 6, characterized in that: The formula for obtaining the equivalent stress increment is: ， in, represents the equivalent stress increment, represents the equivalent stress, represents the first stress component, represents the second stress component, represents the third stress component, represents the first stress increment component, represents the second stress increment component, represents the third stress increment component.

8. The method for constructing a rock constitutive model according to claim 3, characterized in that: The step of comparing the updated predicted stress and the predicted strain with the actual mechanical test results to update the initial fitting parameter variables to final fitting parameter variables includes: Comparing the predicted strain corresponding to the updated predicted stress and the actual stress at the same level with the actual strain to obtain a strain error; Determining whether the strain error is less than a strain error threshold; If the strain error is less than the strain error threshold, the initial fitting parameter variable is determined as the final fitting parameter variable.

9. A system for constructing a rock constitutive model, applied to the method for constructing a rock constitutive model as claimed in any one of claims 1 to 8, characterized in that: The system comprises: A prediction module is used to apply initial conditions to the rock body according to actual mechanical experimental results, wherein the initial conditions include initial stress, initial elastic strain, initial plastic strain, material peak stress and stress increment, and initial fitting parameter variables for constructing an initial rock constitutive model; A judgment module, used for iteratively updating the initial stress through the stress increment to obtain an updated predicted stress; A first analysis module is used to obtain an elastic strain increment through the initial plastic strain, the stress increment and the initial fitting parameter variable, wherein the elastic strain increment includes a first elastic strain increment component, a second elastic strain increment component and a third elastic strain increment component in a three-dimensional coordinate system to characterize the size and direction of the elastic strain increment, and the initial elastic strain is updated through the elastic strain increment to obtain a predicted elastic strain; A second analysis module is used to obtain the size and direction of the plastic strain increment through the updated predicted stress, the initial plastic strain, the stress increment and the initial fitting parameter variable, and update the initial plastic strain based on the plastic strain increment to obtain the predicted plastic strain; A construction module is used to obtain the predicted strain based on the predicted elastic strain and the predicted plastic strain, compare the updated predicted stress and the predicted strain with the actual mechanical experimental results to update the initial fitting parameter variables to the final fitting parameter variables, and construct a final rock constitutive model based on the final fitting parameter variables.

10. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for constructing a rock constitutive model as described in any one of claims 1 to 8 is implemented.

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