A coal body mechanics and gas adsorption analysis method and system based on nanoindentation

Abstract

The present application relates to the technical field of gas adsorption analysis, and discloses a coal body mechanics and gas adsorption analysis method and system based on nanoindentation, which comprises the following steps: obtaining micro mechanics data by using pre-configured methane gas to perform adsorption-desorption treatment on a target coal body sample; collecting pressure term data of the methane gas in the pores of the target coal body sample and a change curve of the methane gas pressure over time to obtain a methane gas diffusion coefficient; combining the micro mechanics data, the methane gas diffusion coefficient and the pressure term data to construct a coupling relationship model between the micro mechanics data of the target coal body sample and the gas diffusion behavior of the target coal body sample, and calculating the adsorption-desorption capacity of the methane of the target coal body sample to obtain a correlation analysis result. The present application constructs a coupling correlation relationship between the micro mechanics parameters of the coal body, the pore gas pressure and the gas diffusion behavior, and realizes a leap from traditional static physical property testing to prediction of the dynamic process of coal body gas adsorption-desorption.

Description

Technical Field

[0001] This invention relates to the field of gas adsorption analysis technology, and more specifically, to a coal mechanics and gas adsorption analysis method and system based on nanoindentation. Background Technology

[0002] The adsorption and desorption processes of gas in coal are mainly controlled by the pore and fracture structure characteristics of the coal, including pore size, distribution, connectivity, and the degree of fracture development. These structural parameters directly affect the gas storage space and seepage channels, and are key factors determining the gas migration capacity.

[0003] However, with further research, increasing evidence suggests that the micromechanical properties of coal, such as hardness, elastic modulus, and compressive strength, also significantly influence gas adsorption and migration behavior. These mechanical parameters determine the deformation response and fracture mechanism of coal under stress, thereby regulating the dynamic evolution of the pore and fracture network. For example, elastic deformation of coal under gas pressure changes or external loads alters pore volume, while plastic deformation or brittle fracture may generate new fractures or expand existing ones, significantly affecting the gas desorption rate and seepage path. Currently, there is a lack of effective means to directly link micromechanics with gas dynamics.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0005] To address the problems in related technologies, this invention proposes a method and system for coal mechanics and gas adsorption analysis based on nanoindentation, in order to overcome the aforementioned technical problems existing in the existing related technologies.

[0006] Therefore, the specific technical solution adopted by the present invention is as follows: According to one aspect of the present invention, a method for coal mechanics and gas adsorption analysis based on nanoindentation is provided, comprising: The target coal sample was subjected to adsorption-desorption treatment using pre-configured methane gas to obtain initial data. The desorbed target coal sample was then subjected to indentation treatment to obtain micromechanical data. During the adsorption-desorption process, pressure data of methane gas in the pores of the target coal sample were collected using initial data. The pressure change curve of methane gas over time was obtained from this pressure data, and the diffusion coefficient of methane gas at the corresponding pressure was calculated using a diffusion theory model. A coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior was constructed by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on the coupling model, the adsorption-desorption capacity of methane in the target coal sample was calculated, and the correlation analysis results were obtained.

[0007] Preferably, the target coal sample is subjected to adsorption-desorption treatment using pre-configured methane gas to obtain initial data, and the desorbed target coal sample is then subjected to indentation treatment to obtain micromechanical data. The target coal sample is placed in a high-pressure test tank. A vacuum pump is used to extract all the gas from the high-pressure test tank. When the pressure inside the high-pressure test tank reaches 0 MPa, methane gas is injected into the high-pressure test tank to complete the adsorption of the coal sample. After adsorption is complete, free methane gas is released until the gas pressure inside the high-pressure experimental tank is the same as the external atmospheric pressure, and the adsorbed target coal sample is desorbed. Initial data were obtained by scanning and photographing the desorbed target coal sample using an atomic force microscope. The desorbed target coal sample was indented using a nanoindenter. After indentation to a preset depth, the indenter was lifted until it was completely removed from the target coal sample. The three-dimensional morphology data of the indented target coal sample were obtained by scanning and photographing the sample using an atomic force microscope. Repeat the above steps to obtain initial data and three-dimensional morphology data of different target coal samples, and analyze and process the initial data and three-dimensional morphology data to obtain micromechanical data.

[0008] Preferably, in the adsorption-desorption process, the pressure data of methane gas in the pores of the target coal sample is collected using the initial data, and the pressure change curve of methane gas over time is obtained using the pressure data. The diffusion coefficient of methane gas at the corresponding pressure is obtained by calculating the change curve using a diffusion theory model. Based on the initial data, the pressure data of methane gas in the pores of the target coal sample and the data of methane gas changing over time in the high-pressure experimental tank were collected in real time using a preset pressure sensor. The collected pressure data and methane gas change data over time were processed to construct a methane gas pressure-time change curve. The variation curve is input into a preset diffusion theory model for fitting calculation to obtain the methane gas diffusion coefficient under the corresponding experimental conditions.

[0009] Preferably, a coupling relationship model between the micromechanical data of the target coal sample and the gas diffusion behavior is constructed by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on the coupling relationship model, the adsorption-desorption capacity of methane in the target coal sample is calculated to obtain the correlation analysis results. Mechanical parameters reflecting the structural stability of the target coal sample were extracted from micromechanical data. Among them, mechanical parameters include elastic modulus, hardness, and fracture toughness; The mechanical parameters were correlated with the methane gas diffusion coefficient and the pore gas pressure to establish the correlation between the mechanical parameters and the gas diffusion. Based on the correlation, the adsorption-desorption capacity of methane and gas in target coal samples under different mechanical parameters and different pore gas pressure values ​​is characterized, and a coupling relationship model between the micromechanical data of the target coal samples and the gas diffusion behavior is constructed.

[0010] Preferably, the mechanical parameters are correlated with the methane gas diffusion coefficient and the pore gas pressure to establish a correlation between the mechanical parameters and the gas diffusion. The mathematical expression characterizing the correlation between the mechanical parameters and the gas is as follows: ; In the formula, D The diffusion coefficient (m) of methane in the sample. 2 / s), E This represents the elastic modulus (GPa) of the target coal sample. H Indicates the hardness (GPa) of the target coal sample. Indicates the fracture toughness (MPa·m) of the target coal sample. 0.5 ), P The pressure (MPa) of methane gas in the pores is measured directly by a pressure sensor in real time from the methane pressure in the pores of the coal sample. The reference diffusion coefficient (m) is represented under the reference state. 2 / s), Reference value for elastic modulus (GPa). Reference value for hardness (GPa). The optimal reference value for fracture toughness (MPa·m) 0.5 ), The reference value (MPa) represents the pressure of methane gas in the pores. exp This represents the natural exponential function. a, b, d as well as c All of these represent empirical coefficients for experimental fit.

[0011] Preferably, the expression for inputting the change curve into a preset diffusion theory model for fitting is: ; In the formula, M t The amount of desorbed gas at time t (ml or mol). M ∞ This indicates the total amount of gas that can be desorbed (ml or mol). This represents the dimensionless desorption fraction. n Indicates the modal number, D Indicates the diffusion coefficient of methane gas. t Indicates diffusion time. R This represents the equivalent spherical radius (m) of the target coal sample particles. exp This represents the natural exponential function.

[0012] According to another aspect of the present invention, a coal mechanics and gas adsorption analysis system based on nanoindentation is provided, including a data logger consisting of a micromechanical data module, a coefficient calculation module, and a correlation analysis module forming a closed-loop control loop, so as to realize the correlation analysis between coal and gas adsorption. The micromechanical data module is used to perform adsorption-desorption treatment on the target coal sample using pre-configured methane gas to obtain initial data, and to perform indentation treatment on the desorbed target coal sample to obtain micromechanical data. The coefficient calculation module is used to collect the time-varying curve of methane gas pressure during the adsorption-desorption process, and use the diffusion theory model to calculate the curve to obtain the methane gas diffusion coefficient at the corresponding pressure. The correlation analysis module is used to construct a coupling relationship model between the micromechanical data of the target coal sample and the gas diffusion behavior by combining micromechanical data, gas diffusion coefficient and gas pressure data, and to calculate the adsorption-desorption capacity of methane in the target coal sample based on the coupling relationship model to obtain the correlation analysis results.

[0013] Preferably, it further includes a gas delivery device, a check valve device, a gas pipe device, a testing device, and a data logger; the gas delivery device is connected through the gas pipe device, and a check valve device is provided on the outside of the gas pipe device; the testing device is located inside the gas delivery device, and the data logger is located outside the gas delivery device.

[0014] Preferably, the gas delivery device includes a methane high-pressure tank, a desorption measuring cylinder, a buffer tank, a vacuum pump, and a high-pressure experimental tank; The endotracheal device includes a first pressurized endotracheal tube, a second pressurized endotracheal tube, and a third pressurized endotracheal tube; The high-pressure methane tank is connected to the buffer tank via the first pressurized gas pipe, the buffer tank is connected to the high-pressure experimental tank via the second pressurized gas pipe, and the high-pressure experimental tank, the desorption measuring cylinder, and the vacuum pump are connected via the third pressurized gas pipe.

[0015] Preferably, the testing device includes a first pressure sensor, a second pressure sensor, a connecting platform, a pressure head, an atomic force microscope, a stage, a clamping arm, an adjusting block, a pressure bearing, and a horizontal platform. The check valve device includes a first check valve, a second check valve, a third check valve, a fourth check valve, and a fifth check valve. The first pressure sensor is mounted on the second pressurized gas pipe. The connecting platform is located at the top of the interior of the high-pressure experimental tank. The pressure head and the atomic force microscope are mounted at the bottom of the connecting platform. The pressure bearing is fixedly mounted at the bottom of the high-pressure experimental tank. The adjusting block is located at the top of the pressure bearing. The horizontal platform is located at the top of the adjusting block. The stage is located at the middle of the top of the horizontal platform. The second pressure sensor is located at the top of the horizontal platform and on one side of the stage. The clamping arm is located at the middle of the top of the stage. The first check valve is installed on the first pressurized gas pipe, the second check valve is installed on the second pressurized gas pipe, the third check valve is installed on the third pressurized gas pipe, and the fourth and fifth check valves are installed on the inlet and outlet pipes of the high-pressure test tank.

[0016] The beneficial effects of this invention are as follows: by introducing nanoindentation and atomic force microscopy testing methods under a controlled methane and gas adsorption-desorption experimental environment, micromechanical data of coal body at the nanoscale are obtained, and data on gas pressure changes over time are collected simultaneously during the adsorption-desorption process. Combined with diffusion theory model inversion, the gas diffusion coefficient is obtained, and then the coupling correlation between coal body micromechanical parameters, pore gas pressure and gas diffusion behavior is constructed, realizing the leap from traditional static property testing to prediction of the dynamic process of coal body gas adsorption-desorption. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Fig. 1 This is a flowchart of a coal mechanics and gas adsorption analysis method based on nanoindentation according to an embodiment of the present invention; Fig. 2 This is a schematic diagram of a coal mechanics and gas adsorption analysis system based on nanoindentation according to an embodiment of the present invention; Fig. 3 This is a three-dimensional morphological data image of coal at the nanoscale in a coal mechanics and gas adsorption analysis system based on nanoindentation according to an embodiment of the present invention. Fig. 4 This is a three-dimensional coal body morphology data map at the micrometer scale in a coal body mechanics and gas adsorption analysis system based on nanoindentation according to an embodiment of the present invention.

[0019] In the picture: 1. Methane high-pressure tank; 2. Desorption graduated cylinder; 3-1. First check valve; 3-2. Second check valve; 3-3. Third check valve; 3-4. Fourth check valve; 3-5. Fifth check valve; 4-1. First pressurized gas pipe; 4-2. Second pressurized gas pipe; 4-3. Third pressurized gas pipe; 5. Buffer tank; 6. Vacuum pump; 7-1. First pressure sensor; 7-2. Second pressure sensor; 8. Connecting platform; 9. Pressure head; 10. Atomic force microscope; 11. Stage; 12. Clamping arm; 13. Adjusting block; 14. Pressure vessel; 15. Horizontal platform; 16. High-pressure experimental tank; 17. Data logger. Detailed Implementation

[0020] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0021] According to embodiments of the present invention, a method and system for coal mechanics and gas adsorption analysis based on nanoindentation are provided.

[0022] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Fig. 1 As shown in one embodiment of the present invention, a method for coal mechanics and gas adsorption analysis based on nanoindentation is provided, comprising: The target coal sample was subjected to adsorption-desorption treatment using pre-configured methane gas to obtain initial data. The desorbed target coal sample was then subjected to indentation treatment to obtain micromechanical data. In a preferred embodiment, the step of using pre-configured methane gas to perform adsorption-desorption treatment on the target coal sample to obtain initial data, and then performing indentation treatment on the desorbed target coal sample to obtain micromechanical data, includes: placing the target coal sample in a high-pressure experimental vessel, using a vacuum pump to extract all the gas from the high-pressure experimental vessel, and injecting methane gas into the high-pressure experimental vessel when the pressure inside the vessel reaches 0 MPa to complete the adsorption of the coal sample; after adsorption is complete, releasing the free methane gas until the gas pressure inside the high-pressure experimental vessel matches the external atmospheric pressure, and then indenting the target coal sample after adsorption. The standard coal sample was desorbed; the desorbed target coal sample was scanned and photographed using an atomic force microscope to obtain initial data; the desorbed target coal sample was indented using a nanoindenter, and the indenter was lifted after being indented to a preset depth until it was completely removed from the target coal sample; the indented target coal sample was scanned and photographed using an atomic force microscope to obtain three-dimensional morphological data of the target coal sample; the above steps were repeated to obtain initial data and three-dimensional morphological data of different target coal samples, and the initial data and three-dimensional morphological data were analyzed and processed to obtain micromechanical data.

[0023] During the adsorption-desorption process, pressure data of methane gas in the pores of the target coal sample and the time-varying curve of methane gas pressure were collected. The diffusion theory model was used to calculate the curve to obtain the methane gas diffusion coefficient at the corresponding pressure. As a preferred embodiment, during the adsorption-desorption process, the pressure term data of methane gas in the pores of the target coal sample is collected using the initial data, and the time-varying curve of methane gas pressure is obtained using the pressure term data. The diffusion coefficient of methane gas under the corresponding pressure is obtained by calculating the curve using a diffusion theory model. This includes: based on the initial data, real-time collection of pressure term data of methane gas in the pores of the target coal sample and data on the time-varying methane gas in the high-pressure experimental tank using a preset pressure sensor; processing the collected pressure term data and data on the time-varying methane gas to construct a methane gas pressure-time variation curve; and inputting the variation curve into a preset diffusion theory model for fitting calculation to obtain the methane gas diffusion coefficient under the corresponding experimental conditions.

[0024] It should be noted that the diffusion theory model can be either a single-pore diffusion model or a dual-pore diffusion model.

[0025] A coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior was constructed by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on the coupling model, the adsorption-desorption capacity of methane in the target coal sample was calculated, and the correlation analysis results were obtained.

[0026] It should be noted that the pressure data is obtained by directly measuring the real-time pressure of methane in the pores of the target coal sample using the second pressure sensor.

[0027] In a preferred embodiment, the process involves constructing a coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on this coupling model, the adsorption-desorption capacity of methane in the target coal sample is calculated, yielding correlation analysis results including: extracting mechanical parameters reflecting the structural stability of the target coal sample from the micromechanical data, whereby the mechanical parameters include elastic modulus, hardness, and fracture toughness; correlating the mechanical parameters with the methane gas diffusion coefficient and pore gas pressure values ​​to establish a correlation between the mechanical parameters and gas diffusion; and characterizing the adsorption-desorption capacity of methane and gas in the target coal sample under different mechanical parameters and pore gas pressure values, thereby constructing a coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior.

[0028] In a preferred embodiment, the mechanical parameters are correlated with the methane gas diffusion coefficient and the pore gas pressure to establish a correlation between the mechanical parameters and the gas diffusion. The mathematical expression characterizing the correlation between the mechanical parameters and the gas is as follows: ; In the formula, D The diffusion coefficient (m) of methane in the sample. 2 / s), E This represents the elastic modulus (GPa) of the target coal sample. H Indicates the hardness (GPa) of the target coal sample. Indicates the fracture toughness (MPa·m) of the target coal sample. 0.5 ), P The pressure (MPa) of methane gas in the pores is measured directly by a pressure sensor in real time from the methane pressure in the pores of the coal sample. The reference diffusion coefficient (m) is represented under the reference state. 2 / s), Reference value for elastic modulus (GPa). Reference value for hardness (GPa). The optimal reference value for fracture toughness (MPa·m) 0.5 ), The reference value (MPa) represents the pressure of methane gas in the pores. exp This represents the natural exponential function. a, b, d as well as c All of these represent empirical coefficients for experimental fit.

[0029] In a preferred embodiment, the expression for inputting the change curve into a preset diffusion theory model for fitting is as follows: ; In the formula, M t The amount of desorbed gas at time t (ml or mol). M ∞ This indicates the total amount of gas that can be desorbed (ml or mol). This represents the dimensionless desorption fraction. n Indicates the modal number, D Indicates the diffusion coefficient of methane gas. t Indicates diffusion time. R This represents the equivalent spherical radius (m) of the target coal sample particles. exp This represents the natural exponential function.

[0030] According to another embodiment of the invention, such as Fig. 2 As shown, a coal mechanics and gas adsorption analysis system based on nanoindentation is provided, including a data logger composed of a micromechanical data module, a coefficient calculation module, and a correlation analysis module forming a closed-loop control loop, so as to realize the correlation analysis between coal and gas adsorption. The micromechanical data module is used to perform adsorption-desorption treatment on the target coal sample using pre-configured methane gas to obtain initial data, and to perform indentation treatment on the desorbed target coal sample to obtain micromechanical data. The coefficient calculation module is used to collect the time-varying curve of methane gas pressure during the adsorption-desorption process, and use the diffusion theory model to calculate the curve to obtain the methane gas diffusion coefficient at the corresponding pressure. The correlation analysis module is used to construct a coupling relationship model between the micromechanical data of the target coal sample and the gas diffusion behavior by combining micromechanical data, gas diffusion coefficient and gas pressure data, and to calculate the adsorption-desorption capacity of methane in the target coal sample based on the coupling relationship model to obtain the correlation analysis results.

[0031] As a preferred embodiment, it also includes a gas delivery device, a check valve device, a gas pipe device, a testing device, and a data logger 17; The gas delivery device is connected through the gas pipe device, and a check valve device is provided on the outside of the gas pipe device. The testing device is located inside the gas delivery device, and the data logger 17 is located outside the gas delivery device.

[0032] In a preferred embodiment, the gas delivery device includes a methane high-pressure tank 1, a desorption measuring cylinder 2, a buffer tank 5, a vacuum pump 6, and a high-pressure experimental tank 16. The tracheal device includes a first pressurized air tube 4-1, a second pressurized air tube 4-2, and a third pressurized air tube 4-3; The high-pressure methane tank is connected to the buffer tank 5 via the first pressurized gas pipe 4-1. The buffer tank 5 is connected to the high-pressure experimental tank 16 via the second pressurized gas pipe 4-2. The high-pressure experimental tank 16, the desorption measuring cylinder 2, and the vacuum pump 6 are connected via the third pressurized gas pipe 4-3.

[0033] In a preferred embodiment, the testing device includes a first pressure sensor 7-1, a second pressure sensor 7-2, a connecting platform 8, a pressure head 9, an atomic force microscope 10, a stage 11, a clamping arm 12, an adjusting block 13, a pressure bearing 14, and a horizontal platform 15. The check valve device includes a first check valve 3-1, a second check valve 3-2, a third check valve 3-3, a fourth check valve 3-4, and a fifth check valve 3-5; The first pressure sensor 7-1 is mounted on the second pressurized gas pipe 4-2. The connecting platform 8 is located at the top inside the high-pressure experimental tank 16. The bottom end of the connecting platform 8 is provided with the pressure head 9 and the atomic force microscope 10. The pressure bearing 14 is fixedly mounted at the bottom inside the high-pressure experimental tank 16. The adjusting block 13 is located at the top of the pressure bearing 14. The horizontal platform 15 is located at the top of the adjusting block 13. The loading stage 11 is located at the middle of the top of the horizontal platform 15. The second pressure sensor 7-2 is located at the top of the horizontal platform 15 and is located on one side of the loading stage 11. The clamping arm 12 is located at the middle of the top of the loading stage 11. The first check valve 3-1 is installed on the first pressurized gas pipe 4-1, the second check valve 3-2 is installed on the second pressurized gas pipe 4-2, the third check valve 3-3 is installed on the third pressurized gas pipe 4-3, and the fourth check valve 3-4 and the fifth check valve 3-5 are installed on the inlet and outlet pipes of the high-pressure test tank.

[0034] It should be noted that the data logger 17 is located on the outside of the high-pressure experimental tank 16 and is electrically connected to the pressure head 9 and the atomic force microscope 10.

[0035] Specifically, before the analysis experiment begins, the target coal sample is first fixed on the stage 11 using the clamping arm 12, and the adjusting block 13 is controlled to make the horizontal platform 15 and the high-pressure experimental tank 16 at the same level. Then, the vacuum pump 6 is used to extract all the gas in the high-pressure experimental tank 16, so that the experimental environment is in an initial vacuum state. The vacuum pump 6 is then turned off, and the first check valve 3-1 is opened, allowing the methane gas in the methane high-pressure tank 1 to enter the buffer tank 5 through the first pressurization pipe 4-1. The methane gas is then stabilized and regulated by the buffer tank 5 until the first pressure sensor... After the reading of the pressure sensor 7-1 stabilizes, the second check valve 3-2 is opened to allow methane gas to enter the high-pressure experimental tank 16 through the second pressurized gas pipe 4-2, thereby adsorbing the target coal sample held on the stage 11. When the adsorption is complete and the reading of the second pressure sensor 7-2 stabilizes, the fourth check valve 3-4 and the fifth check valve 3-5 are opened to release the free methane gas until the gas pressure inside the high-pressure experimental tank 16 is consistent with the external atmospheric pressure. Then, the external inlet and outlet pipes of the high-pressure experimental tank 16 are connected to the desorption measuring cylinder 2 for desorption treatment.

[0036] Next, as Fig. 3 to Fig. 4 As shown, the atomic force microscope 10 is controlled to scan and photograph the target coal sample; then the indenter 9 is moved to press into the target coal sample, and after reaching the maximum indentation depth, the indenter 9 is lifted and completely removed from the sample; then the atomic force microscope 10 is controlled to scan and photograph the target coal sample again. After the same test is performed on different coal samples, the data recorder 17 is used to perform statistics and calculations to obtain the correlation analysis results.

[0037] It should be noted that during the analysis, there is no need to move the target coal sample; only the indenter 9 and atomic force microscope 10 inside the nanoindenter need to be moved. In addition, vacuum pump 6 is required to evacuate the high-pressure experimental tank 16 and the third pressurized gas pipe 4-3 in each experiment to ensure the accuracy of the experimental data under the corresponding working environment.

[0038] Furthermore, under the action of the indenter 9 inside the nanoindenter, the hardness curve, elastic modulus curve, loading curve, contact stiffness curve, and contact area curve of the target coal sample under different gas pressures can be displayed in real time. The atomic force microscope 10 can clearly display the microscopic texture of the target coal sample surface, such as the arrangement and distribution of nanoparticles, as well as parameters such as pore structure and pore size distribution.

[0039] 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.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for coal mechanics and gas adsorption analysis based on nanoindentation, characterized in that, include: The target coal sample was subjected to adsorption-desorption treatment using pre-configured methane gas to obtain initial data. The desorbed target coal sample was then subjected to indentation treatment to obtain micromechanical data. During the adsorption-desorption process, the pressure term data of methane gas in the pores of the target coal sample is collected using the initial data, and the time-varying curve of methane gas pressure is obtained using the pressure term data. The diffusion theory model is used to calculate the curve and obtain the methane gas diffusion coefficient at the corresponding pressure. A coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior was constructed by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on the coupling model, the adsorption-desorption capacity of methane in the target coal sample was calculated, and the correlation analysis results were obtained.

2. The method for coal mechanics and gas adsorption analysis based on nanoindentation according to claim 1, characterized in that, The process of using pre-configured methane gas to adsorb and desorb the target coal sample to obtain initial data, and then performing indentation treatment on the desorbed target coal sample to obtain micromechanical data includes: The target coal sample is placed in a high-pressure test tank. A vacuum pump is used to extract all the gas from the high-pressure test tank. When the pressure in the high-pressure test tank reaches 0 MPa, methane gas is injected into the high-pressure test tank to complete the adsorption of the coal sample. After adsorption is complete, the free gas is released until the gas pressure inside the high-pressure test tank is the same as the external atmospheric pressure, and the adsorbed target coal sample is desorbed. Initial data were obtained by scanning and photographing the desorbed target coal sample using an atomic force microscope. The desorbed target coal sample was indented using a nanoindenter. After indentation to a preset depth, the indenter was lifted until it was completely removed from the target coal sample. The three-dimensional morphology data of the indented target coal sample were obtained by scanning and photographing the sample using an atomic force microscope. Repeat the above steps to obtain initial data and three-dimensional morphology data of different target coal samples, and analyze and process the initial data and three-dimensional morphology data to obtain micromechanical data.

3. The method for coal mechanics and gas adsorption analysis based on nanoindentation according to claim 1, characterized in that, In the adsorption-desorption process, initial data is collected on the pressure term of methane gas in the pores of the target coal sample. The pressure term data is then used to obtain a time-varying curve of the methane gas pressure. A diffusion theory model is used to calculate the curve, yielding the methane gas diffusion coefficient at the corresponding pressure. Based on the initial data, the pressure term data of methane gas in the pores of the target coal sample and the data of methane gas changing over time in the high-pressure experimental tank were collected in real time using a preset pressure sensor. The collected pressure data and methane gas change data over time were processed to construct a methane gas pressure-time change curve. The variation curve is input into a preset diffusion theory model for fitting calculation to obtain the methane gas diffusion coefficient under the corresponding experimental conditions.

4. The method for coal mechanics and gas adsorption analysis based on nanoindentation according to claim 1, characterized in that, A coupling model between the micromechanical data of the target coal sample and the gas diffusion behavior was constructed by combining micromechanical data, methane gas diffusion coefficient, and pressure term data. Based on the coupling model, the adsorption-desorption capacity of methane in the target coal sample was calculated, and the correlation analysis results included: Mechanical parameters reflecting the structural stability of the target coal sample were extracted from micromechanical data. Among them, mechanical parameters include elastic modulus, hardness, and fracture toughness; The mechanical parameters were correlated with the methane gas diffusion coefficient and the pore gas pressure to establish the correlation between the mechanical parameters and the gas diffusion. Based on the correlation, the adsorption-desorption capacity of methane and gas in target coal samples under different mechanical parameters and different pore gas pressure values ​​is characterized, and a coupling relationship model between the micromechanical data of the target coal samples and the gas diffusion behavior is constructed.

5. The method for coal mechanics and gas adsorption analysis based on nanoindentation according to claim 4, characterized in that, The mechanical parameters are correlated with the methane gas diffusion coefficient and the pore gas pressure to establish a correlation between the mechanical parameters and the gas diffusion. The mathematical expression characterizing this correlation is as follows: ； In the formula, D This represents the diffusion coefficient of methane in the sample. E This represents the elastic modulus of the target coal sample. H Indicates the hardness of the target coal sample. This indicates the fracture toughness of the target coal sample. P This indicates the pressure of methane gas in the pores. Represents the reference diffusion coefficient under reference conditions. This represents a reference value for the modulus of elasticity. Reference values ​​indicating hardness. The optimal reference value for fracture toughness. This represents a reference value indicating the pressure of methane gas in the pores. exp This represents the natural exponential function. a, b, d as well as c All of these represent empirical coefficients for experimental fit.

6. The method for coal mechanics and gas adsorption analysis based on nanoindentation according to claim 3, characterized in that, The expression for inputting the change curve into the preset diffusion theory model for fitting calculation is as follows: ； In the formula, M t This represents the amount of desorbed gas at time t. M ∞ This indicates the total amount of gas that can be desorbed. This represents the dimensionless desorption fraction. n Indicates the modal number, D Indicates the diffusion coefficient of methane gas. t Indicates diffusion time. R This represents the equivalent spherical radius of the target coal sample particles. exp This represents the natural exponential function.

7. A coal mechanics and gas adsorption analysis system based on nanoindentation, used to implement the coal mechanics and gas adsorption analysis method based on nanoindentation as described in any one of claims 1-6, characterized in that, It includes a data logger consisting of a closed-loop control loop formed by a micromechanical data module, a coefficient calculation module, and a correlation analysis module, in order to realize the correlation analysis between coal body and gas adsorption; The micromechanical data module is used to perform adsorption-desorption treatment on the target coal sample using pre-configured methane gas to obtain initial data, and to perform indentation treatment on the desorbed target coal sample to obtain micromechanical data. The coefficient calculation module is used to collect the time-varying curve of methane gas pressure during the adsorption-desorption process, and use the diffusion theory model to calculate the curve to obtain the methane gas diffusion coefficient at the corresponding pressure. The correlation analysis module is used to construct a coupling relationship model between the micromechanical data of the target coal sample and the gas diffusion behavior by combining micromechanical data, gas diffusion coefficient and gas pressure data, and to calculate the adsorption-desorption capacity of methane in the target coal sample based on the coupling relationship model to obtain the correlation analysis results.

8. The coal mechanics and gas adsorption analysis system based on nanoindentation according to claim 7, characterized in that, It also includes gas delivery devices, check valve devices, gas tubing devices, testing devices, and data loggers; The gas delivery device is connected through the gas pipe device, and a check valve device is provided on the outside of the gas pipe device. The testing device is located inside the gas delivery device, and the data logger is located outside the gas delivery device.

9. The coal mechanics and gas adsorption analysis system based on nanoindentation according to claim 8, characterized in that, The gas delivery device includes a high-pressure methane tank, a desorption measuring cylinder, a buffer tank, a vacuum pump, and a high-pressure experimental tank; The endotracheal device includes a first pressurized endotracheal tube, a second pressurized endotracheal tube, and a third pressurized endotracheal tube; The high-pressure methane tank is connected to the buffer tank via the first pressurized gas pipe, the buffer tank is connected to the high-pressure experimental tank via the second pressurized gas pipe, and the high-pressure experimental tank, the desorption measuring cylinder, and the vacuum pump are connected via the third pressurized gas pipe.

10. The coal mechanics and gas adsorption analysis system based on nanoindentation according to claim 9, characterized in that, The testing device includes a first pressure sensor, a second pressure sensor, a connecting platform, a pressure head, an atomic force microscope, a stage, a clamping arm, an adjusting block, a pressure bearing, and a horizontal platform. The check valve device includes a first check valve, a second check valve, a third check valve, a fourth check valve, and a fifth check valve. The first pressure sensor is mounted on the second pressurized gas pipe. The connecting platform is located at the top inside the high-pressure experimental tank. The bottom end of the connecting platform is equipped with the pressure head and the atomic force microscope. The pressure bearing is fixedly mounted at the bottom inside the high-pressure experimental tank. The adjusting block is located at the top of the pressure bearing. The horizontal platform is located at the top of the adjusting block. The loading stage is located at the middle of the top of the horizontal platform. The second pressure sensor is located at the top of the horizontal platform and on one side of the loading stage. The clamping arm is located at the middle of the top of the loading stage. The first check valve is installed on the first pressurized gas pipe, the second check valve is installed on the second pressurized gas pipe, the third check valve is installed on the third pressurized gas pipe, and the fourth and fifth check valves are installed on the inlet and outlet pipes of the high-pressure test tank.

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