Method and device for confirming stress critical value of shallow base point coal body of rock burst

Abstract

The present application relates to the technical field of coal mining, and more particularly to a method and device for confirming a stress critical value of shallow base point coal body under rock burst, comprising: processing target rock burst mine samples to obtain a first sample model and a second sample model; loading the first sample model using a stress control method to obtain first sample model parameters; Hopkinson impact processing of the second sample model to obtain dynamic parameters of the second sample model and state information of coal blocks of different particle sizes; based on the state information of the coal blocks, using sphericity fractal dimension to classify the impact damage strength of the coal body to obtain damage classification indicators; dynamic and static combined loading processing of the second sample model using the first sample model parameters and the dynamic parameters of the second sample model; and based on the damage classification indicators, obtaining a stress value of the shallow base point coal body. The present application realizes scientific guidance for setting a critical value of shallow base point coal body stress monitoring, and provides a theoretical basis for setting a critical value of a shallow base point coal body stress monitoring index.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method and apparatus for confirming the critical stress value of coal body at shallow foundation points of rockburst. Background Technology

[0002] Although various measures have been taken in recent years to prevent and control rockbursts, rockburst accidents still occur frequently, indicating that rockbursts have become one of the problems restricting the safe development of coal mines in my country.

[0003] For monitoring the static load of coal, production units mostly use borehole stress gauges to monitor the stress within the coal body. However, there is a lack of unified understanding and scientific guidance on determining the critical values ​​of coal stress monitoring indicators, and a quantitative solution has not yet been provided from a theoretical perspective. As a result, the setting of critical values ​​for coal stress monitoring indicators can only rely on the experience of technical personnel. In many cases, only the relative change in coal stress during the monitoring process is used as the basis, and the depth of utilization of the absolute value of coal stress data is insufficient. This can lead to distortion of coal stress monitoring results to a certain extent, affecting the early warning effect of rockburst and the selection of stress control measures. This brings a certain degree of uncertainty to the safe mining of mines prone to rockbursts.

[0004] Borehole stress gauges typically detect significant stress changes only after substantial borehole deformation. This means that gauges closer to the roadway surface provide richer and more pronounced stress data. Currently, stress detection in shallow coal seams relies on dynamic adjustments based on technicians' experience, lacking scientific rigor and inherent uncertainty. Therefore, proposing a method for determining the critical values ​​of stress monitoring indicators in shallow coal seams, with theoretical support, could improve the accuracy and reliability of rockburst monitoring and early warning systems.

[0005] In conclusion, designing an accurate and reliable method for determining the critical stress value of coal bodies at shallow foundation points is a problem that urgently needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a method for confirming the critical stress value of coal body at shallow base points of rockburst, so as to solve the problems of low accuracy and poor effect of existing monitoring of the critical stress value of coal body at shallow base points of rockburst.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for confirming the critical stress value of coal body at shallow foundation points of rockburst, comprising:

[0008] Obtain a target rockburst mine sample, process the target rockburst mine sample to obtain a first sample model and a second sample model;

[0009] The first sample model is loaded using a stress control method to obtain the parameters of the first sample model;

[0010] The second sample model was subjected to Hopkinson impact processing to obtain the dynamic parameters of the second sample model and the state information of coal blocks of different particle sizes.

[0011] Based on the state information of coal blocks with different particle sizes, the impact damage intensity of the coal body is classified using the sphericity fractal dimension to obtain a damage classification index.

[0012] The second sample model is subjected to dynamic and static combined loading using the parameters of the first sample model and the dynamic parameters of the second sample model. Based on the damage classification index, the stress value of the coal body at the shallow base point is obtained.

[0013] Preferably, the step of obtaining a target rockburst mine sample and processing the target rockburst mine sample to obtain a first sample model and a second sample model includes:

[0014] The target rockburst mine samples were processed into cylindrical specimens of varying volumes. The cylindrical specimens were randomly selected for size measurement, weight measurement, and ultrasonic testing to obtain a first sample model and a second sample model.

[0015] Preferably, the loading process of the first sample model using the stress control method to obtain the parameters of the first sample model includes:

[0016] The first sample model is subjected to uniaxial compression and loaded using a stress control method to obtain a stress-strain curve. The parameters of the first sample model are obtained by analyzing the stress-strain curve based on the mechanical parameters of the coal sample.

[0017] Preferably, the step of performing Hopkinson impact processing on the second sample model to obtain coal block state information of different particle sizes includes:

[0018] The second sample model was subjected to impact operations with different incident gas pressures to obtain the dynamic strength of coal with different strain rates;

[0019] Based on the dynamic strength of coal at different strain rates, the morphology of coal fragments after impact under different strain rates is analyzed to obtain surface morphology information of coal blocks with different particle sizes.

[0020] Three-dimensional structure reconstruction is performed based on three-dimensional coordinates, and sphericity data of coal blocks are obtained based on the surface morphology information of coal blocks with different particle sizes.

[0021] Fractal statistics were used to analyze the sphericity data of coal blocks with different strain rates to obtain the state information of coal blocks with different particle sizes.

[0022] Preferably, the method of classifying the impact damage intensity of coal body based on the state information of coal blocks of different particle sizes using the sphericity fractal dimension to obtain damage classification indicators includes:

[0023] Based on the severity of the impact damage to coal, a classification system is established using the sphericity fractal dimension. The classification index for the degree of coal impact damage is established by the sphericity fractal dimension of the broken coal blocks, namely no impact manifestation, weak impact manifestation, and strong impact manifestation.

[0024] Preferably, the step of performing dynamic and static combined loading processing on the second sample model using the parameters of the first sample model, and obtaining the stress value of the shallow foundation point coal body based on the damage classification index, includes:

[0025] A dynamic-static combined loading experiment was conducted on the second sample model. Based on the parameters of the first sample model, different dynamic load incident air pressures were set to obtain the surface morphology information of coal blocks of different particle sizes, thereby obtaining their sphericity. By analyzing the sphericity within different particle size ranges, the fractal dimension of the sphericity of the coal under the dynamic-static combined loading condition was determined. The impact manifestation intensity caused by the combined conditions was determined by referring to the damage classification index, and the critical value of coal stress was obtained.

[0026] Preferably, the first sample model and the second sample model use similar coal samples with consistent physical properties.

[0027] The present invention also provides a device for confirming the critical stress value of coal body at shallow foundation points of rockburst, comprising:

[0028] The model building module acquires target rockburst mine samples, processes the target rockburst mine samples, and obtains a first sample model and a second sample model.

[0029] The first sample module uses a stress control method to load the first sample model and obtain the parameters of the first sample model.

[0030] The Hopkinson impact module is used to perform Hopkinson impact processing on the second sample model to obtain the dynamic parameters of the second sample model and the state information of coal blocks of different particle sizes.

[0031] The grading index module, based on the state information of coal blocks of different sizes, uses the sphericity fractal dimension to classify the impact damage intensity of the coal body, and obtains the damage grading index.

[0032] The coal stress value module uses the parameters of the first sample model and the dynamic parameters of the second sample model to perform dynamic and static combined loading processing on the second sample model, and obtains the shallow base point coal stress value based on the damage classification index.

[0033] This invention also provides a device for confirming the critical stress value of coal body at shallow foundation points of rockburst, comprising:

[0034] Memory, used to store computer programs;

[0035] A processor is used to execute the computer program to implement the steps of the method for confirming the critical value of coal body stress at shallow base points in rockburst.

[0036] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and the computer program, when executed by a processor, performs the steps of the above-described method for confirming the critical value of coal body stress at shallow base points in rockburst.

[0037] The present invention provides a method for confirming the critical value of coal body stress at shallow base points in rockburst. By processing the target rockburst mine sample, a first sample model and a second sample model are obtained. Based on the sphericity fractal dimension, the state information of coal blocks of different particle sizes is classified. By performing uniaxial compression operation and dynamic-static combined loading operation on the second sample model, the method achieves scientific guidance for setting the critical value of coal body stress monitoring index at shallow base points, thereby improving the scientific nature of rockburst monitoring and early warning effects. Attached Figure Description

[0038] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0039] Figure 1 A flowchart of a first specific embodiment of a method for confirming the critical stress value of coal body at shallow foundation points of rockburst provided by the present invention;

[0040] Figure 2 This is a structural block diagram of a device for confirming the critical value of coal body stress at shallow foundation points in rockburst, provided in an embodiment of the present invention. Detailed Implementation

[0041] The core of this invention is to provide a method for confirming the critical value of coal body stress at shallow base points of rockburst. By performing uniaxial compression operation and dynamic-static combined loading operation on a second sample model, the critical value of coal body stress monitoring index can be accurately and reliably set.

[0042] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please refer to Figure 1 , Figure 1 The flowchart illustrates a first specific embodiment of the method for confirming the critical stress value of coal seam at shallow foundation points in rockburst, provided by the present invention; the specific operation steps are as follows:

[0044] Step S101: Obtain a target rockburst mine sample, process the target rockburst mine sample to obtain a first sample model and a second sample model;

[0045] The target rockburst mine samples were processed into cylindrical specimens of varying volumes. The cylindrical specimens were randomly selected for size measurement, weight measurement and ultrasonic testing to obtain the first sample model and the second sample model.

[0046] The first sample model and the second sample model use similar coal samples with consistent physical properties.

[0047] Step S102: Load the first sample model using the stress control method to obtain the parameters of the first sample model;

[0048] The first sample model is subjected to uniaxial compression and loaded using a stress control method to obtain a stress-strain curve. The parameters of the first sample model are obtained by analyzing the stress-strain curve based on the mechanical parameters of the coal sample.

[0049] Step S103: Perform Hopkinson impact processing on the second sample model to obtain the dynamic parameters of the second sample model and the state information of coal blocks of different particle sizes;

[0050] The second sample model was subjected to impact operations with different incident gas pressures to obtain the dynamic strength of coal with different strain rates;

[0051] Based on the dynamic strength of coal at different strain rates, the morphology of coal fragments after impact under different strain rates is analyzed to obtain surface morphology information of coal blocks with different particle sizes.

[0052] Three-dimensional structure reconstruction is performed based on three-dimensional coordinates, and sphericity data of coal blocks are obtained based on the surface morphology information of coal blocks with different particle sizes.

[0053] Fractal statistics were used to analyze the sphericity data of coal blocks with different strain rates to obtain the state information of coal blocks with different particle sizes.

[0054] Step S104: Based on the state information of coal blocks with different particle sizes, the impact damage intensity of the coal body is classified using the sphericity fractal dimension to obtain the damage classification index;

[0055] Based on the severity of the impact damage to coal, a classification system is established using the sphericity fractal dimension. The classification index for the degree of coal impact damage is established by the sphericity fractal dimension of the broken coal blocks, namely no impact manifestation, weak impact manifestation, and strong impact manifestation.

[0056] Step S105: Using the parameters of the first sample model and the dynamic parameters of the second sample model, perform dynamic and static combined loading processing on the second sample model, and obtain the stress value of the shallow base point coal body based on the damage classification index.

[0057] A dynamic-static combined loading experiment was conducted on the second sample model. Based on the parameters of the first sample model, different dynamic load incident air pressures were set to obtain the surface morphology information of coal blocks of different particle sizes, thereby obtaining their sphericity. By analyzing the sphericity within different particle size ranges, the fractal dimension of the sphericity of the coal under the dynamic-static combined loading condition was determined. The impact manifestation intensity caused by the combined conditions was determined by referring to the damage classification index, and the critical value of coal stress was obtained.

[0058] This embodiment provides a method for confirming the critical value of stress in coal bodies at shallow foundation points for rockburst. By conducting uniaxial compression tests, Hopkinson impact tests, and combined static and dynamic loading tests on coal, it scientifically guides the setting of critical values ​​for stress monitoring indicators in coal bodies at shallow foundation points. This improves the scientific rigor of rockburst monitoring and early warning, deepens the understanding of the rockburst disaster mechanism, clarifies the effects of static and dynamic loads on rockburst disasters, and identifies the critical static load level or range affecting the intensity of rockburst manifestation, providing a theoretical basis for setting the critical values ​​of stress monitoring indicators in coal bodies at shallow foundation points.

[0059] Based on the above embodiments, this embodiment describes the method for confirming the critical stress value of coal body at shallow foundation points of rockburst, as follows:

[0060] Sampling was conducted at the target rockburst mine, and the sampling methods and specifications were in accordance with the requirements of the national standard "Methods for Determination of Physical and Mechanical Properties of Coal and Rock Part 1: General Sampling Requirements" (GB / T 23561.1-2009).

[0061] The coal collected on site was processed into two types of cylindrical specimens: φ50mm×100mm (first sample model) and φ50mm×50mm (second sample model). The processed coal samples were randomly sampled to carry out size measurement, weight measurement and ultrasonic testing to ensure that the coal samples of the same type used are similar in terms of physical properties, and to reduce the dispersion of experimental results caused by coal anisotropy and heterogeneity.

[0062] Referring to the standard GB / T 25217.2-2010, "Methods for Measurement, Monitoring and Prevention of Rockburst Part 2: Classification of Rockburst Tendency and Determination of Index of Coal" to obtain characterization parameters such as uniaxial compressive strength, dynamic failure time, impact energy index, elastic energy index, residual strength, elastic modulus, Poisson's ratio, acoustic emission ring count, amplitude, and surface strain field of coal, a uniaxial compression experiment was conducted on the first sample model. The loading was carried out using a stress-controlled method (0.5MPa / s-1.0MPa). During the process, a stress-strain monitoring instrument and a non-contact full-field strain measurement system were used to analyze the stress-strain curve, surface strain, and acoustic emission events of the coal sample throughout the uniaxial compression process, and mechanical parameters such as uniaxial compressive strength, residual strength, elastic modulus, Poisson's ratio, and internal friction angle were obtained.

[0063] SHPB impact experiments with different incident gas pressures were conducted on the second sample model to obtain the dynamic strength of coal under different strain rates. The process was recorded by a high-speed camera, and the morphology of coal fragments after impact was analyzed under different strain rates. The surface morphology information of coal blocks with different particle sizes was obtained by a 3D scanner. The obtained surface 3D coordinates were used as the basis for reconstructing the 3D structure to obtain its sphericity. Fractal statistics were used to statistically analyze the sphericity characteristics of coal fragments under different strain rates.

[0064] Based on the severity of the impact damage to coal during the experiment, the intensity of the impact damage to coal is classified according to the obtained sphericity fractal dimension. In other words, the grading index of the degree of coal impact damage is established by the sphericity fractal dimension of the broken coal block, namely no impact manifestation, weak impact manifestation, and strong impact manifestation. The specific grading index needs to be determined according to the severity of the damage shown by the coal under impact in the field.

[0065] A dynamic-static combined loading experiment was conducted on the second sample model. First, the static load was set to 20% of the uniaxial compressive strength, and the incident gas pressure of the dynamic load was 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, and 0.8MPa. Five dynamic-static combined loading experiments were conducted for each combination mode. During the experiment, a high-speed camera was used to record the coal impact damage process, and a 3D scanner was used to obtain the surface morphology information of coal blocks of different sizes to obtain their sphericity. By analyzing the sphericity within different particle size ranges, the fractal dimension value of the sphericity of the coal under the dynamic-static combined loading condition was determined. The impact manifestation intensity caused by the combined condition was determined by referring to the previously obtained grading index characterizing the degree of coal impact damage.

[0066] Repeat the above dynamic and static load combination experiment on coal. The static load is 30%, 40%, 50%, 60%, 70%, and 80% of the uniaxial compressive strength. The dynamic load corresponding to each static load level is set to 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, and 0.8MPa. Five loading experiments are carried out for each dynamic and static load combination mode. Analyze the sphericity fractal dimension value of coal after load failure under different dynamic and static load combination modes. Refer to the previously obtained grading index characterizing the degree of coal impact failure to determine the impact manifestation intensity caused by the combination conditions.

[0067] The uniaxial compressive strength and the dynamic load settings are not limited to the above settings and can be of different gradients. In this embodiment, no limitation is made.

[0068] Therefore, a total of 56 dynamic and static load combination modes are formed by 7 static load levels and 8 dynamic load levels, thereby finding the critical level or range (SW, SS) of static load that causes weak impact and strong impact to appear in coal. That is to say, when the static load reaches the critical level (SW) or range, coal will show significant dynamic damage when subjected to a small dynamic load; when the static load reaches the critical level (SS) or range, coal will induce strong dynamic damage when subjected to a small dynamic load.

[0069] Different criteria are used for different rockburst hazard zones. Specifically, in a high-risk rockburst zone, the SW criterion is used for rockburst early warning; in a low-risk rockburst zone, the SS criterion is used. Therefore, the critical level of static load obtained from the above experiments can be used as the basis for setting the critical value of the stress monitoring index for shallow foundation coal seams.

[0070] This invention provides a method for confirming the critical stress value of coal body at shallow foundation points in response to rockburst. It utilizes stress control methods to obtain static mechanical parameters. Based on these parameters, a dynamic load experiment is conducted by applying different dynamic load incident air pressures to a coal body model. The resulting static load critical level serves as the basis for setting the critical value of the stress monitoring index for coal body at shallow foundation points. This scientifically guides the setting of the critical value of the stress monitoring index for coal body at shallow foundation points, thereby improving the scientific validity of rockburst monitoring and early warning effects. It identifies the critical static load level or range that affects the intensity of rockburst manifestation, providing a theoretical basis for setting the critical value of the stress monitoring index for coal body at shallow foundation points.

[0071] Please refer to Figure 2 , Figure 2 This invention provides a structural block diagram of a device for confirming the critical stress value of coal seam at shallow foundation points of rockburst; the specific device may include:

[0072] The model building module 100 acquires a target rockburst mine sample, processes the target rockburst mine sample, and obtains a first sample model and a second sample model.

[0073] The first sample module 200 uses a stress control method to load the first sample model and obtain the parameters of the first sample model.

[0074] The Hopkinson impact module 300 is used to perform Hopkinson impact processing on the second sample model to obtain the dynamic parameters of the second sample model and the state information of coal blocks of different particle sizes.

[0075] The grading index module 400, based on the state information of coal blocks of different particle sizes, uses the sphericity fractal dimension to classify the impact damage intensity of the coal body, and obtains the damage grading index.

[0076] The coal stress value module 500 uses the parameters of the first sample model and the dynamic parameters of the second sample model to perform dynamic and static combined loading processing on the second sample model, and obtains the shallow base point coal stress value based on the damage classification index.

[0077] This embodiment of the device for confirming the critical value of coal body stress at shallow base points of rockburst is used to implement the aforementioned method for confirming the critical value of coal body stress at shallow base points of rockburst. Therefore, the specific implementation of the device for confirming the critical value of coal body stress at shallow base points of rockburst can be found in the embodiment section of the aforementioned method for confirming the critical value of coal body stress at shallow base points of rockburst. For example, the model construction module 100, the first sample module 200, the Hopkinson impact module 300, the grading index module 400, and the coal body stress value module 500 are respectively used to implement steps S101, S102, S103, S104, and S105 in the aforementioned method for confirming the critical value of coal body stress at shallow base points of rockburst. Therefore, the specific implementation can be referred to the description of the corresponding embodiments, which will not be repeated here.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0080] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of the invention pertain.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0082] The above provides a detailed description of the method and apparatus for confirming the critical stress value of coal seam at shallow foundation points in rockburst, as provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

[0083] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any of the following techniques known in the art, or a combination thereof: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0084] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0085] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

Claims

1. A method for confirming the critical stress value of coal body at shallow foundation points of rockburst, characterized in that, include: A target rockburst mine sample is obtained, and the target rockburst mine sample is processed to obtain a first sample model and a second sample model with different volumes. The first sample model and the second sample model are made of the same type of coal sample with consistent physical properties. The first sample model is loaded using a stress control method to obtain a stress-strain curve. The parameters of the first sample model are obtained by analyzing the stress-strain curve based on the mechanical parameters of the coal sample. The second sample model was subjected to Hopkinson impact processing to obtain dynamic parameters of the second sample model and state information of coal blocks of different particle sizes; including: The second sample model was subjected to impact operations with different incident gas pressures to obtain the dynamic strength of coal with different strain rates; Based on the dynamic strength of coal at different strain rates, the morphology of coal fragments after impact under different strain rates is analyzed to obtain surface morphology information of coal blocks with different particle sizes. Three-dimensional structure reconstruction is performed based on three-dimensional coordinates, and sphericity data of coal blocks are obtained based on the surface morphology information of coal blocks with different particle sizes. Fractal statistical methods were used to statistically analyze the sphericity data of coal blocks with different strain rates to obtain the state information of coal blocks with different particle sizes; Based on the state information of coal blocks with different particle sizes, the impact damage intensity of the coal body is classified using the sphericity fractal dimension to obtain a damage classification index. Using the parameters of the first sample model and the dynamic parameters of the second sample model, the second sample model is subjected to dynamic and static combined loading processing. Based on the damage classification index, the stress value of the shallow foundation point coal body is obtained, including: A dynamic-static combined loading experiment was conducted on the second sample model. Based on the parameters of the first sample model, static loads of different intensities were set. The static loads were set according to the uniaxial compressive strength and the incident air pressure of the dynamic loads of different intensities. The surface morphology information of coal blocks of different particle sizes was obtained to obtain their sphericity. By analyzing the sphericity in different particle size ranges, the fractal dimension of the sphericity of the coal under the dynamic-static combined loading condition was determined. The impact manifestation intensity caused by the combined conditions was determined by referring to the failure classification index, and the critical value of coal stress was obtained.

2. The method for confirming the critical stress value of coal body at shallow foundation points of rockburst as described in claim 1, characterized in that, The process of obtaining target rockburst mine samples and processing them to obtain a first sample model and a second sample model includes: The target rockburst mine samples were processed into cylindrical specimens of varying volumes. The cylindrical specimens were randomly selected for size measurement, weight measurement, and ultrasonic testing to obtain a first sample model and a second sample model.

3. The method for confirming the critical stress value of coal body at shallow foundation points of rockburst as described in claim 1, characterized in that, The loading process of the first sample model using the stress control method to obtain the parameters of the first sample model includes: The first sample model is subjected to uniaxial compression and loaded using a stress control method.

4. The method for confirming the critical stress value of coal body at shallow foundation points of rockburst as described in claim 1, characterized in that, Based on the state information of coal blocks with different particle sizes, the impact damage intensity of the coal body is classified using the sphericity fractal dimension, resulting in damage classification indices including: Based on the severity of the impact damage to coal, a classification system is established using the sphericity fractal dimension. The classification index for the degree of coal impact damage is established by the sphericity fractal dimension of the broken coal blocks, namely no impact manifestation, weak impact manifestation, and strong impact manifestation.

5. A device for confirming the critical stress value of coal seam at shallow foundation points of rockburst, characterized in that, include: The model building module acquires a target rockburst mine sample, processes the target rockburst mine sample, and obtains a first sample model and a second sample model with different volumes. The first sample model and the second sample model use the same type of coal sample with consistent physical properties. The first sample module uses a stress control method to load the first sample model to obtain a stress-strain curve. Based on the analysis of the coal sample mechanical parameters, the parameters of the first sample model are obtained. The Hopkinson impact module is used to perform Hopkinson impact processing on the second sample model to obtain dynamic parameters of the second sample model and state information of coal blocks of different particle sizes, including: The second sample model was subjected to impact operations with different incident gas pressures to obtain the dynamic strength of coal with different strain rates; Based on the dynamic strength of coal at different strain rates, the morphology of coal fragments after impact under different strain rates is analyzed to obtain surface morphology information of coal blocks with different particle sizes. Three-dimensional structure reconstruction is performed based on three-dimensional coordinates, and sphericity data of coal blocks are obtained based on the surface morphology information of coal blocks with different particle sizes. Fractal statistical methods were used to statistically analyze the sphericity data of coal blocks with different strain rates to obtain the state information of coal blocks with different particle sizes; The grading index module, based on the state information of coal blocks of different sizes, uses the sphericity fractal dimension to classify the impact damage intensity of the coal body, and obtains the damage grading index. The coal stress value module uses the parameters of the first sample model and the dynamic parameters of the second sample model to perform dynamic and static combined loading processing on the second sample model. Based on the failure classification index, it obtains the shallow base point coal stress value. This includes conducting dynamic and static combined loading experiments on the second sample model, setting static loads of different intensities based on the parameters of the first sample model. The static loads are set according to the uniaxial compressive strength and the incident air pressure of the dynamic load at different pressures. The surface morphology information of coal blocks of different particle sizes is obtained to obtain their sphericity. By analyzing the sphericity within different particle size ranges, the fractal dimension value of the sphericity of the coal under the dynamic and static combined loading conditions is determined. The impact manifestation intensity caused by the combined conditions is determined by referring to the failure classification index, and the critical value of coal stress is obtained.

6. A device for confirming the critical stress value of coal seam at shallow foundation points of rockburst, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the method for confirming the critical stress value of coal body at shallow base points of rockburst as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the method for confirming the critical stress value of coal body at shallow base points of rockburst as described in any one of claims 1 to 4.

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