Mudstone fatigue softening simulation device and method

Abstract

The invention discloses a mudstone fatigue softening simulation device and method. The device comprises a parameter setting module, a data acquisition module, a central control module, a fluid circulation simulation module, a loading control module, a sample clamping device, a monitoring module, a data analysis module and a display module. The method comprises the following steps: S1, setting parameters through a parameter setting module; acquiring and recording data through a data acquisition module; s2, the central control module simulates a circulation process through a fluid circulation simulation module; s3, applying an alternating or continuous load through a loading control module; s4, clamping the to-be-detected mudstone sample through a sample clamping device, and monitoring in real time through a monitoring module; and S5, processing and analyzing the data through a data analysis module to obtain fatigue softening characteristics, and displaying a simulation result through a display module. The device has the beneficial effects that the fatigue softening process of the mudstone under the cyclic loading action of the pore fluid under the actual geological condition can be accurately simulated.

Description

Technical Field

[0001] The invention relates to the technical field of mudstone fatigue softening simulation, and in particular to a mudstone fatigue softening simulation device and method. Background Art

[0002] Geological engineering is an engineering science that studies the engineering properties of geological bodies, engineering surveys, design, construction and monitoring. In geological engineering, rock is the main material that constitutes the earth's crust, and its mechanical properties are crucial to engineering construction and the stability of the geological environment. Mudstone, as a common sedimentary rock, often exhibits fatigue softening characteristics in geological engineering due to its low strength and high plasticity. Therefore, studying the fatigue softening behavior of mudstone under pore fluid cyclic loading is of great significance for evaluating the stability and safety of geological engineering. Rock mechanics is a discipline that studies the deformation and failure laws of rocks under stress. In rock mechanics, the mechanical properties of rocks are affected by many factors, including the composition, structure, temperature, pressure of rocks, and the presence of pore fluids. The presence of pore fluids in rocks can change the stress state of rocks, reduce the effective stress of rocks, and thus affect the mechanical behavior of rocks. Therefore, the fatigue softening simulation technology of mudstone under pore fluid cyclic loading needs to fully consider the relevant theories and methods of rock mechanics. However, the existing fluid simulation is not realistic, resulting in inaccurate simulation data; at the same time, the analysis of simulation data is inaccurate, and it is not visualized, which is not easy to observe.

[0003] Existing technology involves static pressure testing of mudstone using traditional rock mechanics testing equipment. This technology mainly uses standard rock mechanics testing instruments in physical laboratories to apply static pressure to mudstone samples and measure their stress-strain response and crack formation process. During the test, physical parameters such as compressive strength and elastic modulus of mudstone are usually recorded, and the mechanical properties of mudstone are evaluated based on these parameters.

[0004] 1) Lack of dynamic loading simulation: Existing technologies mainly focus on testing the mechanical properties of mudstone under static pressure, but lack simulation and analysis of mudstone behavior under dynamic loads (such as pore fluid cyclic loading). Under actual formation conditions, mudstone is often affected by complex dynamic loads, and it is difficult to fully evaluate its mechanical properties and stability by static testing alone.

[0005] 2) Multi-field coupling effects are not fully considered: Traditional mechanical testing equipment usually fails to simulate the influence of the coupling effects of multi-field factors such as temperature, pressure and fluid on mudstone properties. In practical applications, these multi-field coupling effects have an important influence on the mechanical behavior and permeability of mudstone.

[0006] 3) Data collection and analysis limitations: Although traditional technologies can collect basic mechanical parameters of mudstone, they are limited in real-time data collection, efficient data processing, and complex data analysis. In particular, for more complex analyses such as fatigue softening characteristics and permeability changes, existing technologies often fail to provide in-depth insights.

[0007] 4) Limited ability to display and explain experimental results: Existing technologies are relatively limited in terms of intuitive display and in-depth explanation of experimental results, making it difficult to provide researchers with intuitive and easy-to-understand explanations of the results, which affects the application and promotion of experimental results.

[0008] Although existing technologies provide basic testing methods for the mechanical properties of mudstone, they have obvious technical defects in dynamic loading simulation, multi-field coupling effect analysis, efficient data processing and result display, etc. In contrast, the mudstone fatigue softening simulation system based on mathematical formulas and algorithms can more comprehensively simulate actual formation conditions, provide more accurate mudstone mechanical and permeability performance evaluation, and more efficient data analysis and result display capabilities. Summary of the invention

[0009] The purpose of the present invention is to provide a mudstone fatigue softening simulation device, which can accurately simulate the fatigue softening process of mudstone under actual geological conditions when subjected to cyclic loading of porous fluid. Through this device, researchers can have a deeper understanding of the mechanical behavior of mudstone in a complex geological environment, and provide a more reliable engineering design and safety assessment basis for the exploitation of underground resources such as oil and natural gas.

[0010] Another object of the present invention is to provide a mudstone fatigue softening simulation method, which can accurately simulate the fatigue softening process of mudstone under actual geological conditions when subjected to cyclic loading of porous fluid. Through this method, researchers can have a deeper understanding of the mechanical behavior of mudstone in a complex geological environment, and provide a more reliable engineering design and safety assessment basis for the exploitation of underground resources such as oil and natural gas.

[0011] The present invention is implemented as follows: a mudstone fatigue softening simulation device, comprising:

[0012] Parameter setting module, used to set the temperature and pressure parameters during the simulation;

[0013] Data acquisition module, used to collect and record temperature, pressure, flow rate, stress, strain, and permeability in real time during the simulation process;

[0014] A central control module, which is electrically connected to the parameter setting module and the data acquisition module;

[0015] A fluid circulation simulation module, which is electrically connected to the central control module and is used to inject fluid into the mudstone sample to be tested to simulate the circulation process of pore fluid in the actual formation;

[0016] A loading control module, which is electrically connected to the central control module and is used to accurately apply and control the load to the fluid circulation simulation module;

[0017] A sample clamping device, which is used to fix and clamp the mudstone sample to be tested;

[0018] A monitoring module, which is electrically connected to the central control module and is used to monitor the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time;

[0019] A data analysis module, which is electrically connected to the central control module and is used to calculate the stress-strain relationship, fatigue softening rate, and permeability change parameters of the mudstone under pore fluid cyclic loading to obtain the fatigue softening characteristics of the mudstone;

[0020] The display module is electrically connected to the central control module and is used to display the simulation results.

[0021] Preferably, the fluid circulation simulation module comprises:

[0022] a high-precision pump connected to a storage tank containing formation fluid;

[0023] The pipeline system has two ends connected to the high-precision pump and the storage tank respectively, and the middle of the pipeline system is connected to the mudstone sample to be tested.

[0024] A temperature control system, comprising a heater and a cooler, which are respectively arranged on the pipeline system and are used to simulate temperature conditions of formations at different depths;

[0025] A pressure monitoring and regulating system, which is arranged on the pipeline system and is used to monitor the pressure changes of the fluid in real time to ensure the simulated pressure conditions;

[0026] Wherein, a sensor is arranged in the storage tank for real-time monitoring of changes in the properties of the fluid.

[0027] Preferably, the loading control module includes:

[0028] Pressurizing device: It is an electric pressurizing device or a hydraulic pressurizing device, used to apply alternating or continuous load to the mudstone sample to be tested;

[0029] Sensor system: It uses force sensors and displacement sensors to monitor the load and deformation of the mudstone sample in real time to ensure accurate application of the load;

[0030] Control system: It is electrically connected to the pressurizing device and the sensor system, and is used to control the frequency, size and time of loading, and simulate the stress state of mudstone in the formation.

[0031] Preferably, the monitoring module includes a deformation sensor, a stress sensor, a temperature sensor and a fluid pressure sensor, which are used to monitor the parameter changes of the mudstone sample to be tested during the experiment in real time; the monitoring module is connected to the data acquisition module through a data transmission interface to ensure real-time transmission and recording of monitoring data.

[0032] A method for simulating fatigue softening of mudstone, the device for simulating fatigue softening of mudstone described in any one of the above, comprising the following steps:

[0033] S1. Setting the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading through the parameter setting module; collecting and recording the data in the experimental process through the data acquisition module;

[0034] S2, the central control module simulates the circulation process of pore fluid in the actual formation through the fluid circulation simulation module;

[0035] S3, applying alternating or continuous loads to the mudstone sample to be tested through a loading control module to simulate the stress state of the mudstone in the actual formation;

[0036] S4, clamping the mudstone sample to be tested by a sample clamping device, and then monitoring the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time by a monitoring module;

[0037] S5. Process and analyze the data through the data analysis module to obtain the fatigue softening characteristics of mudstone under pore fluid cyclic loading, and display the simulation results through the display module.

[0038] Preferably, the parameter setting module sets the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading by Miner criterion or Palmgren-Miner linear cumulative damage model;

[0039] Miner's criteria are;

[0040]

[0041] D represents the total damage accumulation;

[0042] N i represents the number of cyclic loading in stage i;

[0043] N f，if It represents the fatigue life of the material under the stress level in stage i;

[0044] n represents the total number of loading stages;

[0045] When D = 1, the material reaches fatigue failure;

[0046] The Palmgren-Miner linear cumulative damage model is;

[0047]

[0048] D represents the total damage accumulation;

[0049] S i represents the stress amplitude at stage i;

[0050] S max represents the maximum stress bearing capacity of stage i;

[0051] k represents the damage sensitivity constant of the material, which is determined experimentally;

[0052] N i represents the number of cyclic loading in stage i;

[0053] N f，if It represents the fatigue life of the material under the stress level in stage i;

[0054] n represents the total number of loading stages;

[0055] A platform for comprehensively simulating the fatigue softening behavior of mudstone under pore fluid cyclic loading conditions, based on the permeability model of effective stress principle or the permeability model considering damage evolution;

[0056] The permeability model based on the effective stress principle describes the change of mudstone permeability under the action of interstitial fluid, as shown below;

[0057] k=k0exp(-ασ')

[0058] k is the current permeability;

[0059] k0 is the initial permeability;

[0060] α is the permeability attenuation constant;

[0061] σ' is the effective stress, which is the total stress minus the void pressure;

[0062] The formula for calculating effective stress is:

[0063] σ'=σ-βp

[0064] σ is the total pressure;

[0065] p is the pore pressure;

[0066] β is the Biot coefficient;

[0067] Permeability model formulation considering damage evolution;

[0068]

[0069] k is the current permeability;

[0070] k0 is the initial permeability;

[0071] D represents the total damage accumulation;

[0072] D max is the maximum amount of damage accumulation until failure occurs;

[0073] m is a parameter related to the permeability characteristics of the material.

[0074] Preferably, the data analysis module performs real-time processing on the data during data collection, including filtering, smoothing, and calibration;

[0075] In the filtering algorithm, the state prediction formula;

[0076]

[0077] In the filtering algorithm, the state update formula;

[0078]

[0079] in, For the predicted state, To update the status, K k is the Kalman gain matrix, y k is the observed value, A, B, C are the system matrices respectively;

[0080] Smoothing algorithm formula;

[0081]

[0082] Among them, y(t) is the smoothed data point, and x(i) is the original data;

[0083] Calibration algorithm formula;

[0084] Y=aX+b

[0085] Among them, X is the original signal output by the sensor, Y is the corresponding physical quantity, and a and b are calibration coefficients, which are preset according to the characteristic parameters of the sensor.

[0086] Preferably, in S5, the data analysis module further performs in-depth statistics, comparison and trend analysis on the fact-processed data to obtain fatigue softening laws of mudstone under pore fluid cyclic loading;

[0087] The trend analysis method is to use multiple linear regression to perform trend analysis on stress, strain, and permeability parameters;

[0088] The multiple linear regression model was;

[0089] Y=β0+β1X1+β2X2+...+β n X n

[0090] Among them, Y is the predictor variable, X1, X2, ..., X n For different input variables, β0, β1, β2, …, β n is the regression coefficient.

[0091] The beneficial effect of the present invention is that it can accurately simulate the fatigue softening process of mudstone under actual geological conditions when subjected to pore fluid cyclic loading. Through this device, researchers can have a deeper understanding of the mechanical behavior of mudstone in complex geological environments, providing a more reliable basis for engineering design and safety assessment for the exploitation of underground resources such as oil and natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 It is a schematic diagram of a mudstone fatigue softening simulation device of the present invention.

[0093] Figure 2 The present invention is a flow chart of a mudstone fatigue softening simulation method. DETAILED DESCRIPTION

[0094] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0095] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or other elements or combinations thereof.

[0096] like Figure 1-2 As shown, a mudstone fatigue softening simulation device of the present invention comprises:

[0097] The parameter setting module 1 is used to set the temperature and pressure parameters during the simulation process.

[0098] The data acquisition module 2 is used to collect and record the temperature, pressure, flow rate, stress, strain and permeability in real time during the simulation process.

[0099] The central control module 3 is electrically connected to the parameter setting module 1 and the data acquisition module 2 .

[0100] The fluid circulation simulation module 4 is electrically connected to the central control module 3 and is used to inject fluid into the mudstone sample to be tested to simulate the circulation process of the pore fluid in the actual formation. As a preferred embodiment, the fluid circulation simulation module 4 includes: a high-precision pump connected to a storage tank, in which formation fluid is contained; a pipeline system, whose two ends are respectively connected to the high-precision pump and the storage tank, and the middle of the pipeline system is connected to the mudstone sample to be tested; a temperature control system, which includes a heater and a cooler, which are respectively arranged on the pipeline system to simulate the temperature conditions of formations at different depths; a pressure monitoring and regulation system, which is arranged on the pipeline system to monitor the pressure changes of the fluid in real time to ensure the simulated pressure conditions; wherein a sensor is arranged in the storage tank to monitor the property changes of the fluid in real time.

[0101] The loading control module 5 is electrically connected to the central control module 3 and is used to accurately apply and control the load to the fluid circulation simulation module 4. Preferably, the loading control module 5 includes: a pressurizing device: an electric pressurizing device or a hydraulic pressurizing device, used to apply an alternating or continuous load to the mudstone sample to be tested; a sensor system: a force sensor and a displacement sensor are used to monitor the load and the deformation of the mudstone sample to be tested in real time to ensure accurate application of the load; a control system: a control system is electrically connected to the pressurizing device and the sensor system, used to control the frequency, size and time of the loading, and simulate the stress state of the mudstone in the formation.

[0102] A sample clamping device 6, which is used to fix and clamp the mudstone sample to be tested;

[0103] The monitoring module 7 is electrically connected to the central control module 3 and is used to monitor the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time. As a preferred embodiment, the monitoring module 7 includes a deformation sensor, a stress sensor, a temperature sensor and a fluid pressure sensor, which are used to monitor the parameter changes of the mudstone sample to be tested in real time during the experiment; the monitoring module is connected to the data acquisition module through a data transmission interface to ensure the real-time transmission and recording of the monitoring data.

[0104] A data analysis module 8, which is electrically connected to the central control module 3, and is used to calculate the stress-strain relationship, fatigue softening rate, and permeability change parameters of mudstone under pore fluid cyclic loading to obtain the fatigue softening characteristics of the mudstone;

[0105] The display module 9 is electrically connected to the central control module 3 and is used to display the simulation results.

[0106] A method for simulating fatigue softening of mudstone, the device for simulating fatigue softening of mudstone described in any one of the above, comprising the following steps:

[0107] S1, setting the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading through parameter setting module 1; collecting and recording the data in the experimental process through data acquisition module 2;

[0108] The parameter setting module 1 sets the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading through the Miner criterion or the Palmgren-Miner linear cumulative damage model;

[0109] Miner's criteria are;

[0110]

[0111] D represents the total damage accumulation;

[0112] N i represents the number of cyclic loading in stage i;

[0113] N f，if It represents the fatigue life of the material under the stress level in stage i;

[0114] n represents the total number of loading stages;

[0115] When D = 1, the material reaches fatigue failure;

[0116] The Palmgren-Miner linear cumulative damage model is;

[0117]

[0118] D represents the total damage accumulation;

[0119] S i represents the stress amplitude at stage i;

[0120] S max represents the maximum stress bearing capacity of stage i;

[0121] k represents the damage sensitivity constant of the material, which is determined experimentally;

[0122] N i represents the number of cyclic loading in stage i;

[0123] N f，if It represents the fatigue life of the material under the stress level in stage i;

[0124] n represents the total number of loading stages;

[0125] A platform for comprehensively simulating the fatigue softening behavior of mudstone under pore fluid cyclic loading conditions, based on the permeability model of effective stress principle or the permeability model considering damage evolution;

[0126] The permeability model based on the effective stress principle describes the change of mudstone permeability under the action of interstitial fluid, as shown below;

[0127] k=k0exp(-ασ')

[0128] k is the current permeability;

[0129] k0 is the initial permeability;

[0130] α is the permeability attenuation constant;

[0131] σ' is the effective stress, which is the total stress minus the void pressure;

[0132] The formula for calculating effective stress is:

[0133] σ'=σ-βp

[0134] σ is the total pressure;

[0135] p is the pore pressure;

[0136] β is the Biot coefficient;

[0137] Permeability model formulation considering damage evolution;

[0138]

[0139] k is the current permeability;

[0140] k0 is the initial permeability;

[0141] D represents the total damage accumulation;

[0142] D max is the maximum amount of damage accumulation until failure occurs;

[0143] m is a parameter related to the permeability characteristics of the material.

[0144] The data analysis module 2 performs real-time processing on the data during the data collection process, including filtering, smoothing, and calibration;

[0145] In the filtering algorithm, the state prediction formula;

[0146]

[0147] In the filtering algorithm, the state update formula;

[0148]

[0149] in, For the predicted state, To update the status, K k is the Kalman gain matrix, yk is the observed value, A, B, C are the system matrices respectively;

[0150] Smoothing algorithm formula;

[0151]

[0152] Among them, y(t) is the smoothed data point, and x(i) is the original data;

[0153] Calibration algorithm formula;

[0154] Y=aX+b

[0155] Among them, X is the original signal output by the sensor, Y is the corresponding physical quantity, and a and b are calibration coefficients, which are preset according to the characteristic parameters of the sensor.

[0156] S2, the central control module 3 simulates the circulation process of pore fluid in the actual formation through the fluid circulation simulation module 4;

[0157] S3, applying an alternating or continuous load to the mudstone sample to be tested through the loading control module 5 to simulate the stress state of the mudstone in the actual formation;

[0158] S4, clamping the mudstone sample to be tested by the sample clamping device 6, and then monitoring the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time by the monitoring module 7;

[0159] S5, the data is processed and analyzed by the data analysis module 8 to obtain the fatigue softening characteristics of mudstone under the pore fluid circulation loading, and the simulation results are displayed by the display module 9. In S5, the data analysis module further performs in-depth statistics, comparison and trend analysis on the data after fact processing to obtain the fatigue softening law of mudstone under the pore fluid circulation loading;

[0160] The trend analysis method is to use multiple linear regression to perform trend analysis on stress, strain, and permeability parameters;

[0161] The multiple linear regression model was;

[0162] Y=β0+β1X1+β2X2+...+β n X n

[0163] Among them, Y is the predictor variable, X1, X2, ..., X n For different input variables, β0, β1, β2, …, β n is the regression coefficient.

[0164] In summary, the present invention can accurately simulate the fatigue softening process of mudstone under actual geological conditions when subjected to cyclic loading of porous fluids. It can enable researchers to have a deeper understanding of the mechanical behavior of mudstone in complex geological environments, and provide a more reliable basis for engineering design and safety assessment for the exploitation of underground resources such as oil and natural gas.

Claims

1. A mudstone fatigue softening simulation device, characterized in that: include: Parameter setting module, used to set the temperature and pressure parameters during the simulation; Data acquisition module, used to collect and record temperature, pressure, flow rate, stress, strain, and permeability in real time during the simulation process; A central control module, which is electrically connected to the parameter setting module and the data acquisition module; A fluid circulation simulation module, which is electrically connected to the central control module and is used to inject fluid into the mudstone sample to be tested to simulate the circulation process of pore fluid in the actual formation; A loading control module, which is electrically connected to the central control module and is used to accurately apply and control the load to the fluid circulation simulation module; A sample clamping device, which is used to fix and clamp the mudstone sample to be tested; A monitoring module, which is electrically connected to the central control module and is used to monitor the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time; A data analysis module, which is electrically connected to the central control module and is used to calculate the stress-strain relationship, fatigue softening rate, and permeability change parameters of the mudstone under pore fluid cyclic loading to obtain the fatigue softening characteristics of the mudstone; The display module is electrically connected to the central control module and is used to display the simulation results.

2. The intelligent device for simulating fatigue softening of mudstone under pore fluid cyclic loading according to claim 1, characterized in that: The fluid circulation simulation module includes: a high-precision pump connected to a storage tank containing formation fluid; The pipeline system has two ends connected to the high-precision pump and the storage tank respectively, and the middle of the pipeline system is connected to the mudstone sample to be tested. A temperature control system, comprising a heater and a cooler, which are respectively arranged on the pipeline system and are used to simulate temperature conditions of formations at different depths; A pressure monitoring and regulating system, which is arranged on the pipeline system and is used to monitor the pressure changes of the fluid in real time to ensure the simulated pressure conditions; Wherein, a sensor is arranged in the storage tank for real-time monitoring of changes in the properties of the fluid.

3. The intelligent device for simulating mudstone fatigue softening under pore fluid cyclic loading as claimed in claim 2, characterized in that: The loading control module comprises: Pressurizing device: It is an electric pressurizing device or a hydraulic pressurizing device, used to apply alternating or continuous load to the mudstone sample to be tested; Sensor system: It uses force sensors and displacement sensors to monitor the load and deformation of the mudstone sample in real time to ensure accurate application of the load; Control system: It is electrically connected to the pressurizing device and the sensor system, and is used to control the frequency, size and time of loading to simulate the stress state of mudstone in the formation.

4. The intelligent device for simulating fatigue softening of mudstone under pore fluid cyclic loading as claimed in claim 2, characterized in that: The monitoring module includes a deformation sensor, a stress sensor, a temperature sensor and a fluid pressure sensor, which are used to monitor the parameter changes of the mudstone sample to be tested during the experiment in real time; the monitoring module is connected to the data acquisition module through a data transmission interface to ensure the real-time transmission and recording of the monitoring data.

5. A method for simulating mudstone fatigue softening, using the mudstone fatigue softening simulation device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Setting the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading through the parameter setting module; collecting and recording the data in the experimental process through the data acquisition module; S2, the central control module simulates the circulation process of pore fluid in the actual formation through the fluid circulation simulation module; S3, applying alternating or continuous loads to the mudstone sample to be tested through a loading control module to simulate the stress state of the mudstone in the actual formation; S4, clamping the mudstone sample to be tested by a sample clamping device, and then monitoring the deformation, stress, temperature and fluid parameters of the mudstone sample to be tested in real time by a monitoring module; S5. Process and analyze the data through the data analysis module to obtain the fatigue softening characteristics of mudstone under pore fluid cyclic loading, and display the simulation results through the display module.

6. The method for simulating fatigue softening of mudstone according to claim 5, characterized in that: In S1, the parameter setting module sets the temperature and pressure parameters in the simulation process of mudstone fatigue softening under pore fluid cyclic loading through the Miner criterion or the Palmgren-Miner linear cumulative damage model; Miner's criteria are; D represents the total damage accumulation; N i represents the number of cyclic loading in stage i; N f，if It represents the fatigue life of the material under the stress level in stage i; n represents the total number of loading stages; When D = 1, the material reaches fatigue failure; The Palmgren-Miner linear cumulative damage model is: D represents the total damage accumulation; S i represents the stress amplitude at stage i; S max represents the maximum stress bearing capacity of stage i; k represents the damage sensitivity constant of the material, which is determined experimentally; N i represents the number of cyclic loading in stage i; N f，if It represents the fatigue life of the material under the stress level in stage i; n represents the total number of loading stages; A platform for comprehensively simulating the fatigue softening behavior of mudstone under pore fluid cyclic loading conditions, based on the permeability model of effective stress principle or the permeability model considering damage evolution; The permeability model based on the effective stress principle describes the change of mudstone permeability under the action of interstitial fluid, as shown below; k=k0exp(-ασ') k is the current permeability; k0 is the initial permeability; α is the permeability attenuation constant; σ' is the effective stress, which is the total stress minus the void pressure; The formula for calculating effective stress is: σ'=σ-βp σ is the total pressure; p is the pore pressure; β is the Biot coefficient; Permeability model formulation considering damage evolution; k is the current permeability; k0 is the initial permeability; D represents the total damage accumulation; D max is the maximum amount of damage accumulation until failure occurs; m is a parameter related to the permeability characteristics of the material.

7. The method for simulating fatigue softening of mudstone according to claim 5, characterized in that: In S1, the data analysis module performs real-time processing on the data during the data collection process, including filtering, smoothing, and calibration; In the filtering algorithm, the state prediction formula; In the filtering algorithm, the state update formula; in, For the predicted state, To update the status, K k is the Kalman gain matrix, y k is the observed value, A, B, C are the system matrices respectively; Smoothing algorithm formula; Among them, y(t) is the smoothed data point, and x(i) is the original data; Calibration algorithm formula; Y=aX+b Among them, X is the original signal output by the sensor, Y is the corresponding physical quantity, and a and b are calibration coefficients, which are preset according to the characteristic parameters of the sensor.

8. The method for simulating fatigue softening of mudstone according to claim 7, characterized in that: In S5, the data analysis module further performs in-depth statistics, comparison and trend analysis on the fact-processed data to obtain the fatigue softening law of mudstone under pore fluid cyclic loading; The trend analysis method is to use multiple linear regression to perform trend analysis on stress, strain, and permeability parameters; The multiple linear regression model was; Y=β0+β1X1+β2X2+...+β n X n Among them, Y is the predictor variable, X1, X2, ..., X n For different input variables, β0, β1, β2, …, β n is the regression coefficient.

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