Shear creep parameter acquisition method and system based on low constant shear rate test

Abstract

The invention provides a shear creep parameter acquisition method and system based on a low constant shear rate test, and the method comprises the steps: applying a constant shear rate to a rock sample to carry out a constant shear rate test, and solving to obtain a first shear creep parameter; applying constant shear stress to the rock sample to perform a constant shear stress test, and solving to obtain a second shear creep parameter; and correcting the first shear creep parameter based on the second shear creep parameter to obtain a correction coefficient. According to the device and the method, relatively accurate shear creep parameters can be obtained through a long-term partial constant shear stress test, the shear creep parameters obtained through a short-term constant shear rate test are corrected to obtain a correction coefficient, and the shear creep parameters of the rock to be tested can be obtained through a relatively short-time constant shear rate test subsequently; and performing correction based on the correction coefficient to obtain an accurate shear creep parameter.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, and more specifically, to a method and system for obtaining shear creep parameters based on low constant shear rate tests. Background Technology

[0002] In the field of rock engineering, shear creep testing is a key method for studying the long-term stability of rocks, and shear creep parameters of rocks can be obtained through shear creep testing.

[0003] Traditional shear creep testing methods typically obtain creep parameters through creep tests under constant stress, but these tests are time-consuming (even taking several months) and cannot obtain the shear creep parameters of rocks in the short term. Summary of the Invention

[0004] This invention addresses the technical problems existing in the prior art by providing a method and system for obtaining shear creep parameters based on low constant shear rate tests, which can quickly and accurately obtain the shear creep parameters of rocks.

[0005] According to a first aspect of the present invention, a method for obtaining shear creep parameters based on a low constant shear rate test is provided, comprising: Prepare rock specimens that meet the standards, and mount the rock specimens on the rock mechanics testing machine for testing; A constant shear rate test was conducted by applying a constant shear rate to the rock sample, and the shear stress of the rock sample at different time points was recorded to obtain multiple sets of time-shear stress data. Substituting multiple sets of time-shear stress data into the constitutive equation under constant shear strain rate conditions, the first shear creep parameter is obtained based on nonlinear regression fitting. A constant shear stress test was conducted by applying a constant shear stress to the rock sample and recording the shear strain of the rock sample at different time points to obtain multiple sets of time-shear strain data. Among them, one shear stress was selected as the constant shear stress from the shear stresses recorded at different time points in the constant shear rate test. Substituting multiple sets of time-shear strain data into the creep equation, the second shear creep parameter is obtained based on nonlinear regression fitting; The first shear creep parameter is corrected based on the second shear creep parameter, and the correction coefficient is obtained; The first shear creep parameter of the rock is obtained based on the constant shear rate test, and the first shear creep parameter is corrected using the correction coefficient to obtain the rock shear creep parameter.

[0006] Based on the above technical solution, the present invention can also be improved as follows.

[0007] Optionally, the step of substituting multiple sets of time-point shear stress data into the constitutive equation under constant shear strain rate conditions, and obtaining the first shear creep parameter based on nonlinear regression fitting, includes: Based on the Hooke-Kelvin model, the constitutive equation under constant shear strain rate conditions is constructed as follows: in, To apply a constant shear rate to the rock sample, t represents the length of the rock sample in the shear direction, and t is the time point of the test. Let be the shear stress at time t. For a constant strain rate, G1 is the elastic modulus of the elastic Hooke element in the Hooke-Kelvin model, G2 is the elastic modulus of the Kelvin element in the Hooke-Kelvin model, η is the viscosity coefficient of the Kelvin element in the Hooke-Kelvin model, and G1, G2 and η are shear creep parameters. Substituting multiple sets of time-shear stress data into the constitutive equation under constant shear strain rate conditions, the first shear creep parameter corresponding to the constant shear rate is obtained by fitting using the nonlinear least squares method.

[0008] Optionally, the step of substituting multiple sets of time-point shear strain data into the creep equation and obtaining the second shear creep parameter based on nonlinear regression fitting includes: Based on long-term actual creep tests, a creep equation is constructed. These tests were conducted under different shear stresses on the rock. The constructed creep equation is as follows: Where τ0 is the constant shear stress applied to the rock sample, and t is the test time point. G1 is the shear strain at time t, G2 is the elastic modulus of the elastic Hooke element in the Hooke-Kelvin model, G2 is the elastic modulus of the Kelvin element in the Hooke-Kelvin model, η is the viscosity coefficient of the Kelvin element in the Hooke-Kelvin model, and G1, G2 and η are shear creep parameters. Substituting multiple sets of time-point shear strain data into the creep equation, the second shear creep parameter corresponding to the constant shear stress is obtained by fitting using the nonlinear least squares method.

[0009] Optionally, the step of correcting the first shear creep parameter based on the second shear creep parameter and obtaining a correction coefficient includes: A correction factor is determined, and the first shear creep parameter is corrected based on the correction factor so that the deviation between the corrected first shear creep parameter and the second shear creep parameter is minimized.

[0010] Optionally, the first shear creep parameter includes the elastic modulus G. 1c G 2c and viscosity coefficient η c The second shear creep parameter includes G 1cr G 2cr and viscosity coefficient η cr ; The step of determining the correction coefficient and correcting the first shear creep parameter based on the correction coefficient to minimize the deviation between the corrected first shear creep parameter and the second shear creep parameter includes: Initialize correction coefficients α, β, and γ. The step of correcting the first shear creep parameter based on these correction coefficients includes: Based on the initial correction coefficients α, β, and γ, the first shear creep parameter is corrected using a linear correction function to obtain the corrected first shear creep parameter. Construct the objective function: min Σ[(η' - η cr ) 2 + (G1' - G 1cr ) 2 + (G2'- G 2cr ) 2 ] Where η', G1', and G2' are the corrected first shear creep parameters, η cr G 1cr G 2cr This is the second shear creep parameter; By continuously adjusting the correction coefficients α, β, and γ to minimize the objective function, the correction coefficients α, β, and γ are determined.

[0011] Optionally, the step of correcting the first shear creep parameter based on the initialized correction coefficients α, β, and γ using a linear correction function to obtain the corrected first shear creep parameter includes: η' = αη c G1' = βG 1c G2' = γG 2c Where G1' and G2' are the corrected elastic moduli, and η' is the corrected viscosity coefficient.

[0012] Optionally, the step of correcting the first shear creep parameter based on the initialized correction coefficients α, β, and γ using a linear correction function to obtain the corrected first shear creep parameter further includes: Based on the initialized correction coefficients α, β, and γ, the first shear creep parameter is corrected using a nonlinear correction function to obtain the corrected first shear creep parameter. The nonlinear correction function includes a polynomial function, an exponential function, or a logarithmic function.

[0013] According to a second aspect of the present invention, a system for obtaining shear creep parameters based on a low constant shear rate test is provided, comprising: The first test module is used to apply a constant shear rate to the rock sample to conduct a constant shear rate test, record the shear stress of the rock sample at different time points, and obtain multiple sets of time point-shear stress data. The first fitting and solving module is used to substitute multiple sets of time-point shear stress data into the constitutive equation under constant shear strain rate conditions, and obtain the first shear creep parameter based on nonlinear regression fitting. The second test module is used to apply constant shear stress to the rock sample to conduct a constant shear stress test, record the shear strain of the rock sample at different time points, and obtain multiple sets of time-shear strain data. Among them, a shear stress is selected as the constant shear stress from the shear stresses recorded at different time points in the constant shear rate test. The second fitting and solving module is used to substitute multiple sets of time-point shear strain data into the creep equation and obtain the second shear creep parameters based on nonlinear regression fitting. The correction module is used to correct the first shear creep parameter based on the second shear creep parameter and obtain the correction coefficient; The acquisition module is used to acquire the first shear creep parameter of the rock based on a constant shear rate test, and to correct the first shear creep parameter using the correction coefficient to acquire the rock shear creep parameter.

[0014] According to a third aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the processor is configured to execute a computer management program stored in the memory to implement the steps of a method for obtaining shear creep parameters based on a low constant shear rate test.

[0015] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer management program stored thereon, which, when executed by a processor, implements the steps of a method for obtaining shear creep parameters based on a low constant shear rate test.

[0016] This invention provides a method and system for obtaining shear creep parameters based on low constant shear rate tests. The method involves applying a constant shear rate to a rock sample to conduct a constant shear rate test and solving for a first shear creep parameter; then applying a constant shear stress to the rock sample to conduct a constant shear stress test and solving for a second shear creep parameter; finally, the first shear creep parameter is corrected based on the second shear creep parameter to obtain a correction coefficient. This invention allows for obtaining relatively accurate shear creep parameters through long-term partial constant shear stress tests, correcting the shear creep parameters obtained from short-term constant shear rate tests to obtain correction coefficients. Subsequently, relatively short-term constant shear rate tests can be used to obtain the shear creep parameters of the rock sample, and accurate shear creep parameters can be obtained by correcting the parameters based on the correction coefficients. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a method for obtaining shear creep parameters based on a low constant shear rate test, as provided in one embodiment of the present invention; Figure 2 This is a schematic diagram of the Hooke-Kelvin model. Figure 3 A schematic diagram of a shear creep parameter acquisition system based on a low constant shear rate test provided in one embodiment of the present invention; Figure 4 A schematic diagram of the hardware structure of a possible electronic device provided by the present invention; Figure 5 This is a schematic diagram of the hardware structure of a possible computer-readable storage medium provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined with each other to form feasible technical solutions. Such combinations are not constrained by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0019] Figure 1A flowchart illustrating a method for obtaining shear creep parameters based on a low constant shear rate test, as provided in one embodiment of the present invention, is shown below. Figure 1 As shown, the method includes the following steps: Step 1: Prepare rock samples that meet the standards and install the rock samples on the rock mechanics testing machine for testing.

[0020] Understandably, the first step is test preparation, specifically preparing standard-compliant rock specimens to ensure their geometry and surface quality meet test requirements. A high-precision servo-controlled rock mechanics testing machine is used, equipped with precise deformation and stress measurement devices.

[0021] Step 2: Apply a constant shear rate to the rock sample to conduct a constant shear rate test, record the shear stress of the rock sample at different time points, and obtain multiple sets of time-shear stress data.

[0022] Understandably, a constant shear rate test is conducted by applying a constant shear rate to a rock sample, and the stress changes over time are recorded to obtain multiple sets of time-shear stress data, forming multiple data pairs.

[0023] Step 3: Substitute multiple sets of time-point shear stress data into the constitutive equation under constant shear strain rate conditions, and obtain the first shear creep parameter based on nonlinear regression fitting.

[0024] Understandably, since the experiment in step 2 was conducted under conditions of constant shear rate, the creep equation was transformed into an equation applicable to conditions of low constant shear rate to describe the characteristics of shear stress variation. The experimental data were then substituted into the transformed equation, and the parameters in the equation were fitted using numerical methods (such as nonlinear least squares). These parameters are the parameters of the creep equation.

[0025] See Figure 2 Taking the Hooke-Kelvin model as an example, this model consists of elastic Hooke elements connected in series with Kelvin elements. Its constitutive equation under constant compressive stress and constant shear rate conditions is derived as follows: 1. When t=0, the shear stress on the model is zero, and the corresponding shear strain is also zero.

[0026] 2. When t>0, shear force is applied to the model, and a constant shear rate v is maintained. The model is in the viscoelastic stage and has not yet entered the plastic stage. The three-parameter model is the primary agent, and the model satisfies the following stress-strain relationship: (1) in, This represents the shear stress of the elastic Hooke element. It is the elastic modulus of the elastic Hooke element. This represents the strain of the elastic Hooke element. This represents the shear stress of the Kelvin element. It is the elastic modulus of the Kelvin element. This indicates the strain of the Kelvin element. It is the strain rate of the Kelvin element.

[0027] From equation (1) above, the rheological equation can be obtained as follows: (2) In the formula: , These represent the derivatives of stress and strain with respect to time, respectively. , This is the shear modulus.

[0028] When t=0, the stress acting on the model is zero. (3) After t=0, a load is applied to the model while maintaining a constant shear rate v, i.e., a constant strain rate. Let the constant shear rate be v, and the length of the specimen in the shear direction be l, then the shear strain... shear strain rate It is a constant.

[0029] (4) Strain increases linearly with time (5) To maintain a constant strain rate The internal stress of the model gradually increases from zero. Substituting the strain conditions (4) and (5) into equation (2), and then according to the initial condition (3), the analytical equation of the shear stress is obtained as follows: (6) Substituting the time-shear stress data obtained in step 2 into the constitutive equation (6) under constant shear strain rate conditions, the first shear creep parameter is obtained based on nonlinear regression fitting. The shear creep parameter includes G1, G2 and η, where G1 is the elastic modulus of the elastic Hooke element in the Hooke-Kelvin model, G2 is the elastic modulus of the Kelvin element in the Hooke-Kelvin model, and η is the viscosity coefficient of the Kelvin element in the Hooke-Kelvin model. G1, G2 and η are the shear creep parameters.

[0030] It should be noted that the embodiments of the present invention use the Hooke-Kelvin model, but other models, such as Maxwell, Kelvin, Burgers, etc., can also be used.

[0031] Step 4: Apply constant shear stress to the rock sample to conduct a constant shear stress test, record the shear strain of the rock sample at different time points, and obtain multiple sets of time-shear strain data. Among them, select one shear stress from the shear stresses recorded at different time points in the constant shear rate test as the constant shear stress.

[0032] Understandably, a partial creep test is performed concurrently with step 2. The so-called creep test is a constant shear stress test in which a constant shear stress is applied to the rock sample. Here, the constant shear stress applied to the rock sample is the shear stress generated by applying a constant shear rate to the rock sample in step 2.

[0033] After applying constant shear stress to the rock sample and conducting the test, the shear strain of the rock sample at different time points is recorded, and multiple sets of time-shear strain data are obtained to form data pairs.

[0034] Step 5: Substitute multiple sets of time-point shear strain data into the creep equation and obtain the second shear creep parameter based on nonlinear regression fitting.

[0035] Understandably, step 4 records multiple sets of time-shear strain data from the constant shear stress test, substitutes them into the creep equation, and fits and solves for the shear creep parameters.

[0036] Based on long-term actual creep tests, a creep equation is constructed. These tests were conducted under different shear stresses on the rock. The constructed creep equation is as follows: Where τ0 is the constant shear stress applied to the rock sample, and t is the test time point. G1 is the shear strain at time t, G2 is the elastic modulus of the elastic Hooke element in the Hooke-Kelvin model, G2 is the elastic modulus of the Kelvin element in the Hooke-Kelvin model, η is the viscosity coefficient of the Kelvin element in the Hooke-Kelvin model, and G1, G2 and η are shear creep parameters. Substituting multiple sets of time-point shear strain data into the creep equation, the second shear creep parameter corresponding to the constant shear stress is obtained by fitting using the nonlinear least squares method.

[0037] Step 6: Correct the first shear creep parameter based on the second shear creep parameter and obtain the correction coefficient.

[0038] Understandably, the shear creep parameters of the rock sample are obtained by fitting different test conditions through steps 3 and 5 above. The shear creep parameters obtained under constant shear rate test are called the first shear creep parameters, and the shear creep parameters obtained under constant shear stress test are called the second shear creep parameters.

[0039] Since the creep equation (7) is derived from long-term actual creep tests, the second shear creep parameter obtained by solving the creep equation (7) is relatively accurate.

[0040] Based on this, in this embodiment of the invention, the first shear creep parameter is corrected based on the second shear creep parameter.

[0041] In one embodiment of the present invention, the step of correcting the first shear creep parameter based on the second shear creep parameter and obtaining a correction coefficient includes: A correction factor is determined, and the first shear creep parameter is corrected based on the correction factor so that the deviation between the corrected first shear creep parameter and the second shear creep parameter is minimized.

[0042] The first shear creep parameter includes the elastic modulus G. 1c G 2c and viscosity coefficient η c The second shear creep parameter includes G 1cr G 2cr and viscosity coefficient η cr .

[0043] Specifically, the process of determining the correction factor includes: Initialize correction coefficients α, β, and γ. Based on the initial correction coefficients α, β, and γ, and using a linear correction function, correct the first shear creep parameter to obtain the corrected first shear creep parameter. Construct the objective function: min Σ[(η' - η cr ) 2 + (G1' - G 1cr ) 2 + (G2'- G 2cr ) 2 ] Where η', G1', and G2' are the corrected first shear creep parameters, η cr G 1cr G 2cr This is the second shear creep parameter; By continuously adjusting the correction coefficients α, β, and γ, the objective function is minimized, and the final correction coefficients α, β, and γ are determined.

[0044] Specifically, based on the initialized correction coefficients α, β, and γ, the first shear creep parameter is corrected using a linear correction function to obtain the corrected first shear creep parameter. The correction formula is as follows: η' = αη c G1' = βG 1c G2' = γG 2c Where G1' and G2' are the corrected elastic moduli, and η' is the corrected viscosity coefficient.

[0045] It should be noted that, based on the correction coefficients α, β, and γ, the first shear creep parameter can be corrected using either a linear correction function or a nonlinear correction function. The nonlinear correction function includes polynomial functions, exponential functions, or logarithmic functions.

[0046] Step 7: Obtain the first shear creep parameter of the rock based on the constant shear rate test, and correct the first shear creep parameter using the correction coefficient to obtain the rock shear creep parameter.

[0047] Understandably, after obtaining the corrected parameters through step 6, the shear creep parameters of the rock under test can be solved by constant shear rate test. Then, the correction coefficient can be used to correct the shear creep parameters solved by constant shear rate test. Thus, accurate rock shear creep parameters can be obtained through short-term constant shear rate test.

[0048] The following example illustrates the method for obtaining shear creep parameters based on low constant shear rate tests provided in this embodiment of the invention.

[0049] Taking granite as an example, a complete rock sample from a granite mass was selected and prepared into a cubic specimen with sides of 50mm × 50mm × 50mm. The surface of the specimen was polished to ensure that the surface flatness error was controlled within 0.01mm, and the geometric dimensions of the specimen were accurately measured. The prepared granite specimen was mounted on a rock shear testing machine and subjected to a shear test at a constant shear rate of 0.001mm / min. The shear stress versus time curve from the start of shearing to failure was recorded. The Hooke-Kelvin model was selected to describe the shear creep behavior of granite. The shear stress at different time points was substituted into the constitutive equation under constant shear strain rate conditions, and the model parameters were fitted using the nonlinear least squares method to obtain the model parameter values ​​corresponding to the constant shear rate, including the elastic modulus G1, G2 and the viscosity coefficient η.

[0050] Then, a small number of existing granite samples were selected for actual shear creep tests. The actual shear creep test involves applying a constant shear stress to the rock sample, recording the shear strain at different time points, and substituting it into the creep equation to obtain the creep parameters.

[0051] The creep parameters obtained from constant shear rate tests are compared with those obtained from actual creep tests. If discrepancies exist, the model parameter fitting method is modified by introducing a weighting factor to weight the parameters under different shear rates, redetermining the model parameters, and then validating them again. This allows the modified model parameters to more accurately describe the shear creep behavior of granite.

[0052] The following is a detailed explanation of the relationship between parameters such as viscosity coefficient η and elastic modulus G1 and G2 in shear creep tests and constant shear rate tests, as well as the correction methods.

[0053] Relationship between parameters (1) From a physical perspective: Whether it is a shear creep test or a constant shear rate test, the obtained parameters such as viscosity coefficient η and elastic modulus G1 and G2 are macroscopic manifestations of the internal microstructure and mechanical properties of the rock. For the same rock material (such as granite), its internal mineral composition, grain structure, degree of fracture development and other factors are relatively stable, so there should be an inherent correlation between these parameters.

[0054] (2) From the perspective of rheological models: Taking the Hooke-Kelvin model as an example, this model is composed of elastic Hooke elements and Kelvin elements connected in series. Under different loading conditions (whether it is a creep test with constant shear stress or a test with constant shear rate), both the elastic and viscous elements in the model participate in the deformation process, but their contribution ratios and manifestations are different. In the shear creep test, when a constant shear stress is applied, the deformation of the rock develops over time, mainly reflecting the viscous flow characteristics of the viscous elements under continuous stress, so that the viscosity coefficient η and elastic modulus G1, G2 and other parameters can be obtained; while in the constant shear rate test, when loaded at a certain shear rate, the shear stress on the rock will gradually adjust over time. At this time, the instantaneous deformation of the elastic element and the rate-dependent deformation of the viscous element work together to reflect the parameters of the rock such as η, G1, G2, etc., but these parameters are manifested under specific shear rate conditions.

[0055] 2. A method for correcting constant shear rate test parameters using partial shear creep test parameters: (1) Establish parameter comparison relationship Comparison parameters were selected: the viscosity coefficient η and elastic modulus G1 and G2 obtained from the shear creep test were compared with the corresponding parameters obtained from the constant shear rate test at different shear rates.

[0056] Analyze the deviation patterns: Through comparative analysis, determine the degree and trend of deviation between the parameters obtained from the two test methods. For example, it may be found that the viscosity coefficient η obtained from the constant shear rate test is generally slightly higher or lower than that from the shear creep test at certain shear rates, and this deviation shows a certain pattern with the change of shear rate or stress level, such as the deviation of η gradually increasing or decreasing with the increase of shear rate; similar deviation patterns may also exist for the elastic modulus G1 and G2.

[0057] (2) Constructing a modified model The modified model based on linear combination: It is assumed that the modified viscosity coefficient η' and elastic moduli G1' and G2' can be expressed as a linear combination of shear creep test parameters and constant shear rate test parameters, that is: η' = αη c G1' = βG 1c G2' = γG 2c Where, η c G 1c G 2c The parameters are obtained from constant shear rate tests. α, β, and γ are weighting coefficients, with values ​​ranging from 0 to 1. They are determined based on the results of parameter comparison analysis so that the corrected parameters η', G1', and G2' can better reflect the actual rheological behavior of rocks.

[0058] Introducing nonlinear correction functions: If the deviation relationship between parameters is complex and exhibits nonlinear characteristics, nonlinear functions can be used to construct the correction model. For example, polynomial, exponential, or logarithmic functions can be used to describe the relationship between constant shear rate test parameters and shear creep test parameters. By fitting the test data, the coefficients and form of the function can be determined, thereby achieving the correction of the constant shear rate test parameters.

[0059] (3) Determine the corrected weights or function coefficients Numerical methods such as least squares are used: data from shear creep tests and constant shear rate tests are substituted into the modified model. The objective function is to minimize the error between the modified parameters and the actual experimental data. Numerical optimization methods such as nonlinear least squares and genetic algorithms are employed to solve for the weight coefficients or function coefficients in the modified model. For example, when determining the weight coefficients α, β, and γ of the linear combination modified model, this can be achieved by minimizing the following objective function: min Σ[(η' i - η i_cr ) 2 + (G1' i - G 1i_cr ) 2 + (G2' i - G 2i_cr ) 2 ] Where, η' i G1' i G2' i For the corrected parameters, η i_cr G 1i_cr G 2i_cr The actual parameters obtained through shear creep tests (which can be used as a reference standard) are represented by i, which indicates different test conditions or data points.

[0060] Based on mechanical analysis and empirical judgment, and combining the mechanical properties of the rock with experimental phenomena, the weighting coefficients or function coefficients are reasonably estimated and adjusted. For example, if the parameters of the shear creep test are considered more accurate under low stress levels, the weight of the shear creep test parameters in the correction model can be appropriately increased; conversely, under high stress or high shear rate, if the parameters of the constant shear rate test are more reliable, the weights can be adjusted accordingly to make the correction results more reasonably reflect the rheological behavior of the rock under different conditions.

[0061] (4) Verify the corrected parameters The corrected parameters are applied to experimental data or practical engineering problems that were not involved in the correction process to predict the shear rheological behavior of rocks, and then compared with actual observation results or existing research findings. For example, the corrected parameters can be used to predict the deformation response of granite under a new shear stress or shear rate. If the predicted results are consistent with actual experimental results or results obtained by other reliable methods, the effectiveness and scientific validity of the correction method can be further verified.

[0062] Using the above methods, the viscosity coefficient η and elastic modulus G1 and G2 obtained from partial shear creep tests can be used to scientifically and reasonably correct the parameters obtained from constant shear rate tests, thereby improving the accuracy and reliability of the parameters and better describing the shear creep characteristics of granite.

[0063] See Figure 3 This invention provides a system for obtaining shear creep parameters based on a low constant shear rate test, according to one embodiment of the present invention. The system includes: The first test module 301 is used to apply a constant shear rate to the rock sample to conduct a constant shear rate test, record the shear stress of the rock sample at different time points, and obtain multiple sets of time point-shear stress data. The first fitting and solving module 302 is used to substitute multiple sets of time-point shear stress data into the constitutive equation under constant shear strain rate conditions, and obtain the first shear creep parameter based on nonlinear regression fitting. The second test module 303 is used to apply constant shear stress to the rock sample to conduct a constant shear stress test, record the shear strain of the rock sample at different time points, and obtain multiple sets of time-shear strain data. Among them, a shear stress is selected as the constant shear stress from the shear stresses recorded at different time points in the constant shear rate test. The second fitting and solving module 304 is used to substitute multiple sets of time-point shear strain data into the creep equation and obtain the second shear creep parameter based on nonlinear regression fitting. The correction module 305 is used to correct the first shear creep parameter based on the second shear creep parameter and obtain the correction coefficient.

[0064] The acquisition module 306 is used to acquire the first shear creep parameter of the rock based on the constant shear rate test, and to correct the first shear creep parameter using the correction coefficient to acquire the rock shear creep parameter.

[0065] It is understood that the shear creep parameter acquisition system based on low constant shear rate test provided by the present invention corresponds to the shear creep parameter acquisition method based on low constant shear rate test provided in the foregoing embodiments. The relevant technical features of the shear creep parameter acquisition system based on low constant shear rate test can be referred to the relevant technical features of the shear creep parameter acquisition method based on low constant shear rate test, and will not be repeated here.

[0066] Please see Figure 4 , Figure 4 This is a schematic diagram illustrating an embodiment of the electronic device provided in this invention. For example... Figure 4 As shown, an embodiment of the present invention provides an electronic device 400, including a memory 410, a processor 420, and a computer program 411 stored in the memory 410 and executable on the processor 420. When the processor 420 executes the computer program 411, it performs the following steps: A constant shear rate test was conducted by applying a constant shear rate to the rock sample, and the shear stress of the rock sample at different time points was recorded to obtain multiple sets of time-shear stress data. Substituting multiple sets of time-shear stress data into the constitutive equation under constant shear strain rate conditions, the first shear creep parameter is obtained based on nonlinear regression fitting. A constant shear stress test was conducted by applying a constant shear stress to the rock sample and recording the shear strain of the rock sample at different time points to obtain multiple sets of time-shear strain data. Among them, one shear stress was selected as the constant shear stress from the shear stresses recorded at different time points in the constant shear rate test. Substituting multiple sets of time-shear strain data into the creep equation, the second shear creep parameter is obtained based on nonlinear regression fitting; The first shear creep parameter is corrected based on the second shear creep parameter, and the correction coefficient is obtained; The first shear creep parameter of the rock is obtained based on the constant shear rate test, and the first shear creep parameter is corrected using the correction coefficient to obtain the rock shear creep parameter.

[0067] Please see Figure 5 , Figure 5 This is a schematic diagram illustrating an embodiment of a computer-readable storage medium provided by the present invention. (See diagram below.) Figure 5 As shown, this embodiment provides a computer-readable storage medium 500 on which a computer program 511 is stored. When the computer program 511 is executed by a processor, it performs the following steps: A constant shear rate test was conducted by applying a constant shear rate to the rock sample, and the shear stress of the rock sample at different time points was recorded to obtain multiple sets of time-shear stress data. Substituting multiple sets of time-shear stress data into the constitutive equation under constant shear strain rate conditions, the first shear creep parameter is obtained based on nonlinear regression fitting. A constant shear stress test was conducted by applying a constant shear stress to the rock sample and recording the shear strain of the rock sample at different time points to obtain multiple sets of time-shear strain data. Among them, one shear stress was selected as the constant shear stress from the shear stresses recorded at different time points in the constant shear rate test. Substituting multiple sets of time-shear strain data into the creep equation, the second shear creep parameter is obtained based on nonlinear regression fitting; The first shear creep parameter is corrected based on the second shear creep parameter, and the correction coefficient is obtained; The first shear creep parameter of the rock is obtained based on the constant shear rate test, and the first shear creep parameter is corrected using the correction coefficient to obtain the rock shear creep parameter.

[0068] This invention provides a method and system for obtaining shear creep parameters based on a low constant shear rate test. The method involves applying a constant shear rate to a rock sample to conduct a constant shear rate test and obtaining a first shear creep parameter; then applying a constant shear stress to the rock sample to conduct a constant shear stress test and obtaining a second shear creep parameter; finally, the first shear creep parameter is corrected based on the second shear creep parameter to obtain a correction coefficient. This invention allows for the acquisition of relatively accurate shear creep parameters through long-term partial constant shear stress tests. The shear creep parameters obtained from short-term constant shear rate tests are then corrected using correction coefficients. Subsequently, relatively short-term constant shear rate tests can be used to obtain the shear creep parameters of the rock sample, and accurate shear creep parameters can be obtained by correcting the parameters using the correction coefficients.

[0069] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0070] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0071] 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 computer, 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. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0072] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0073] 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.

[0074] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. A method for obtaining shear creep parameters based on a low constant shear rate test, characterized by, The method comprises the following steps: a rock sample meeting a standard is prepared, and the rock sample is installed on a rock mechanics testing machine for testing; a constant shear rate test is performed on the rock sample, and shear stresses of the rock sample at different time points are recorded to obtain a plurality of sets of time point-shear stress data; the plurality of sets of time point-shear stress data are substituted into a constitutive equation under a constant shear strain rate condition, and a first shear creep parameter is obtained based on nonlinear regression fitting; a constant shear stress test is performed on the rock sample, and shear strains of the rock sample at different time points are recorded to obtain a plurality of sets of time point-shear strain data, wherein a shear stress selected from the shear stresses of the rock sample at different time points recorded in the constant shear rate test is used as the constant shear stress; the plurality of sets of time point-shear strain data are substituted into a creep equation, and a second shear creep parameter is obtained based on nonlinear regression fitting; the first shear creep parameter is corrected based on the second shear creep parameter, and a correction coefficient is obtained; a first shear creep parameter of a rock is obtained based on a constant shear rate test, and the first shear creep parameter is corrected based on the correction coefficient, so that a shear creep parameter of the rock is obtained.

2. The method of claim 1, wherein, The step of substituting the plurality of sets of time point-shear stress data into the constitutive equation under the constant shear strain rate condition and obtaining the first shear creep parameter based on nonlinear regression fitting comprises the following steps: a constitutive equation under the constant shear strain rate condition is constructed based on a Hooke-Kelvin model; wherein, is a constant shear rate applied to the rock sample, is a length of the rock sample in the shear direction, t is a test time point, is a shear stress at the t time point, is a constant strain rate, G1 is an elastic modulus of an elastic Hooke element in the Hooke-Kelvin model, G2 is an elastic modulus of a Kelvin element in the Hooke-Kelvin model, η is a viscous coefficient of the Kelvin element in the Hooke-Kelvin model, G1, G2, and η are shear creep parameters; the plurality of sets of time point-shear stress data are substituted into the constitutive equation under the constant shear strain rate condition, and a first shear creep parameter corresponding to the constant shear rate is obtained by fitting based on a nonlinear least square method.

3. The method of claim 1, wherein, The step of substituting the plurality of sets of time point-shear strain data into the creep equation and obtaining the second shear creep parameter based on nonlinear regression fitting comprises the following steps: a creep equation is constructed based on a long-term actual creep test, wherein the long-term actual creep test is performed under different shear stresses of the rock, and the constructed creep equation is: wherein τ0 is a constant shear stress applied to the rock sample, t is a test time point, is a shear strain at the t time point, G1 is an elastic modulus of an elastic Hooke element in the Hooke-Kelvin model, G2 is an elastic modulus of a Kelvin element in the Hooke-Kelvin model, η is a viscous coefficient of the Kelvin element in the Hooke-Kelvin model, G1, G2, and η are shear creep parameters; the plurality of sets of time point-shear strain data are substituted into the creep equation, and a second shear creep parameter corresponding to the constant shear stress is obtained by fitting based on a nonlinear least square method.

4. The method of claim 1, wherein, The step of correcting the first shear creep parameter based on the second shear creep parameter and obtaining the correction coefficient comprises the following steps: a correction coefficient is determined, and the first shear creep parameter is corrected based on the correction coefficient, so that a deviation between the corrected first shear creep parameter and the second shear creep parameter is minimized.

5. The method of claim 4, wherein, The first shear creep parameters include an elastic modulus G 1c , 2c and a viscosity coefficient η c , and the second shear creep parameters include G 1cr , G 2cr and a viscosity coefficient η cr ; The step of determining the correction coefficient and correcting the first shear creep parameter based on the correction coefficient, so that a deviation between the corrected first shear creep parameter and the second shear creep parameter is minimized, comprises the following steps: initialization is performed on correction coefficients α, β and γ, and the step of correcting the first shear creep parameter based on the correction coefficient comprises the following steps: the first shear creep parameter is corrected based on a linear correction function according to the initialized correction coefficients α, β and γ, and a corrected first shear creep parameter is obtained; a target function is constructed: min Σ[(η' - η cr ) 2 + (G1' - G 1cr ) 2 + (G2' - G 2cr ) 2 ] wherein η', G1', G2' are the corrected first shear creep parameters, η cr , G 1cr , G 2cr are the second shear creep parameters; By continuously adjusting the correction coefficients α, β, γ, the target function is minimized to determine the correction coefficients α, β, γ.

6. The method of claim 5, wherein, The first shear creep parameter is corrected based on a linear correction function according to the initialized correction coefficients α, β, γ, to obtain a corrected first shear creep parameter, including: η' = aη c G1' = βG 1c G2' = γG 2c Wherein, G1', G2' are the corrected elastic modulus, η' is the corrected viscosity coefficient.

7. The method of claim 5, wherein, The first shear creep parameter is corrected based on a linear correction function according to the initialized correction coefficients α, β, γ, to obtain a corrected first shear creep parameter, further including: The first shear creep parameter is corrected based on a nonlinear correction function according to the initialized correction coefficients α, β, γ, to obtain a corrected first shear creep parameter, wherein the nonlinear correction function includes a polynomial function, an exponential function or a logarithmic function.

8. A shear creep parameter acquisition system based on a low constant shear rate test, characterized by, Including: The first test module is used for applying a constant shear rate to the rock sample to perform a constant shear rate test, recording the shear stress of the rock sample at different time points, and obtaining multiple sets of time point-shear stress data; The first fitting solving module is used for substituting the multiple sets of time point-shear stress data into the constitutive equation under the condition of constant shear strain rate, and obtaining the first shear creep parameter based on nonlinear regression fitting; The second test module is used for applying a constant shear stress to the rock sample to perform a constant shear stress test, recording the shear strain of the rock sample at different time points, and obtaining multiple sets of time point-shear strain data, wherein one shear stress is selected from the shear stress recorded at different time points in the constant shear rate test as the constant shear stress; The second fitting solving module is used for substituting the multiple sets of time point-shear strain data into the creep equation, and obtaining the second shear creep parameter based on nonlinear regression fitting; The correction module is used for correcting the first shear creep parameter based on the second shear creep parameter, and obtaining a correction coefficient; The acquisition module is used for acquiring the first shear creep parameter of the rock based on the constant shear rate test, correcting the first shear creep parameter using the correction coefficient, and acquiring the shear creep parameter of the rock.

9. An electronic device, comprising: The memory, the processor, the processor is used for executing the computer management class program stored in the memory, realizes the step of the shear creep parameter acquisition method based on the low constant shear rate test of any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer management class program is stored on the memory, and the computer management class program is executed by the processor to realize the steps of the shear creep parameter acquisition method based on the low constant shear rate test of any one of claims 1-7.

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