End slope mining coal pillar stability testing method, device, equipment, medium and product

Abstract

The invention belongs to the technical field of end slope mining stability detection, and aims to solve the problems of destructiveness and difficulty in real-time testing of an existing coal pillar stability testing method. The invention provides an end slope mining coal pillar stability testing method, device and equipment, a medium and a product. The method comprises the following steps: determining a voxel density defect of a coal pillar; acquiring the frequency of a micro-seismic event of a slope step above the coal pillar; solving a coal pillar stability coefficient based on the voxel density defect, the micro-seismic event frequency, the equivalent compressive strength of the coal pillar and the actual coal pillar load; the rigidity ratio of the equivalent rigidity of the system to the shear rigidity of the coal pillar is used as a parameter for representing the rigidity stability margin of the coal pillar; and the stability of the end slope mining coal pillar is judged based on strength-rigidity double criteria formed by the stability coefficient and the rigidity ratio of the coal pillar. According to the method, non-contact and online evaluation of the end slope mining coal pillar strength can be realized, and meanwhile, the stability of the coal pillar is judged by combining an improved local mine stiffness theory.

Description

Technical Field

[0001] This invention belongs to the field of end-face mining stability testing technology, specifically relating to a method, apparatus, equipment, medium, and product for testing the stability of coal pillars in end-face mining. Background Technology

[0002] The stability of the coal pillar in end-face mining is the primary factor for safe mining in end-face mining areas. The evolution of stress-fracture-density within the coal pillar between mining chambers cannot be captured by a single method.

[0003] Existing contact stress gauges or anchor strain gauges require drilling and installation, which damages the integrity of the coal pillar, is difficult to maintain, and poses a permanent risk. If the end-face mining tunnels are not supported, personnel cannot enter the tunnels. Monitoring slope stability mainly relies on ground-based interferometric synthetic aperture radar (SAR) outside the mining tunnel to observe the slope surface, but it can only observe the slope surface and cannot solve the problem of internal crack propagation. In addition, ground-based SAR observations are refreshed every 20 minutes, which has insufficient real-time performance. Microseismic or acoustic emission arrays can sense energy release, but the event location error increases with slope obstruction.

[0004] Therefore, existing methods for testing the stability of coal pillars in end-face mining still suffer from destructiveness and difficulty in real-time testing. Summary of the Invention

[0005] In order to solve at least one of the above-mentioned technical problems in the prior art, the present invention provides a method, apparatus, equipment, medium and product for testing the stability of coal pillars in end-face mining.

[0006] This invention is achieved using the following technical solution: a method for testing the stability of coal pillars in end-face mining, comprising the following steps: Multi-view cross-scanning of the coal pillar using muon tomography was employed to reconstruct the voxel density field within the pillar and determine its voxel density defects. The frequency of microseismic events on the slope steps above the pillar was obtained. Coal strength parameters were acquired through indoor rock compression tests, and these parameters were reduced using the Hoek-Brown criterion and combined with the pillar's dimensions to obtain the equivalent compressive strength. The actual coal pillar load was obtained using dependent area theory and the effective bearing area of ​​the overlying load. Based on the voxel density defects, microseismic event frequencies, equivalent compressive strength, and actual load, the coal pillar stability coefficient, characterizing the strength stability margin, was calculated. An improved local mine stiffness theory was introduced, using the ratio of the system's equivalent stiffness to the pillar's shear stiffness as a parameter characterizing the pillar's stiffness stability margin. The stability of the end-face mining coal pillar was assessed using a strength-stiffness dual criterion based on the stability coefficient and the stiffness ratio.

[0007] Preferably, the expression for the coal pillar stability coefficient is: In the formula, The stability coefficient of the coal pillar; The equivalent compressive strength of the coal pillar; This represents the actual coal pillar load. This is a voxel density defect; This is the microseismic attenuation factor; Frequency of microseismic events; It is a natural constant.

[0008] Preferably, the logic for judging the stability of the end-face mining coal pillar based on the strength-stiffness dual criterion composed of the coal pillar stability coefficient and stiffness ratio is as follows: When the stability coefficient of the coal pillar is greater than or equal to a preset safety threshold and the stiffness ratio is greater than 1, the coal pillar is determined to be in a stable state; when the stability coefficient of the coal pillar is greater than or equal to a preset safety threshold and the stiffness ratio is less than or equal to 1, the coal pillar is determined to be in a stiffness-controlled unstable state; when the stability coefficient of the coal pillar is less than a preset safety threshold and the stiffness ratio is greater than 1, the coal pillar is determined to be in a strength-controlled unstable state; when the stability coefficient of the coal pillar is less than a preset safety threshold and the stiffness ratio is less than or equal to 1, the coal pillar is determined to be in a critical instability state, and mining is forcibly stopped or control measures are taken.

[0009] Preferably, the coal pillar is scanned from multiple angles using muon tomography, and the detector used is a self-powered plastic scintillator-silicon photomultiplier flat panel detector. A gantry is set at the entrance of the mining chamber, and a set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors are installed on the gantry. At the same time, a folding telescopic track is laid at the entrance of the mining chamber, and another set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors are sent into a preset position inside the mining chamber by a pulley set on the folding telescopic track.

[0010] Preferably, the voxel density field inside the coal pillar is reconstructed by PoCA-SART inversion, and the density field is converted into a defect field to obtain the voxel density defects of the coal pillar; The expression for the voxel density defect of the coal pillar is: In the formula, This is a voxel density defect; To reconstruct voxel units within the region; The voxel reference density is obtained from the reconstruction at the baseline time. For time windows The estimated voxel density obtained from the reconstruction.

[0011] Preferably, multiple three-component seismographs are installed on the slope steps above the coal pillar by excavating holes or placing mortar bases, and then leveled and oriented. The three-component seismographs are used to obtain the frequency of the microseismic events, and distributed vibration fiber optic sensors are used in conjunction to remotely pick up microseismic events.

[0012] In a second aspect, the present invention also provides a stability testing device for end-slope mining coal pillars, comprising a voxel density defect determination module, a microseismic event frequency acquisition module, an equivalent compressive strength acquisition module for the coal pillar, an actual coal pillar load acquisition module, a coal pillar stability coefficient solution module, a stiffness ratio solution module, and a coal pillar stability combination judgment module; the voxel density defect determination module is used to determine the voxel density defects of the coal pillar based on muon tomography and inversion reconstruction; the microseismic event frequency acquisition module is used to acquire the frequency of microseismic events on the slope steps above the coal pillar based on a three-component seismograph; the equivalent compressive strength acquisition module is used to acquire coal body strength parameters through indoor rock compression tests, and to convert the coal body strength parameters into Hoek-Brew parameters. The equivalent compressive strength of the coal pillar is obtained by subtracting the coal pillar size parameters using the own criterion; the actual coal pillar load acquisition module is used to obtain the actual coal pillar load through the dependent area theory and the effective bearing area of ​​the overlying load on the coal pillar; the coal pillar stability coefficient solution module is used to solve the coal pillar stability coefficient, which characterizes the strength stability margin of the coal pillar, based on voxel density defects, microseismic event frequency, the equivalent compressive strength of the coal pillar, and the actual coal pillar load; the stiffness ratio solution module is used to solve the stiffness ratio of the system equivalent stiffness to the coal pillar shear stiffness based on the improved local mine stiffness theory; the coal pillar stability combination judgment module is used to judge the stability of the end-face mining coal pillar based on the strength-stiffness dual criterion composed of the coal pillar stability coefficient and stiffness ratio.

[0013] In a third aspect, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to implement the end-face mining coal pillar stability testing method.

[0014] In a fourth aspect, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the end-face coal pillar stability testing method.

[0015] In a fifth aspect, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the end-face mining coal pillar stability testing method.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention employs multi-view cross-scanning of a coal pillar using muon tomography to invert and reconstruct the voxel density field within the coal pillar, thereby determining the voxel density defects. It also acquires the frequency of microseismic events on the slope steps above the coal pillar; obtains coal body strength parameters through indoor rock compression tests, and reduces these parameters using the Hoek-Brown criterion and coal pillar size parameters to obtain the equivalent compressive strength of the coal pillar; obtains the actual coal pillar load using dependent area theory and the effective bearing area of ​​the overlying load; solves for the coal pillar stability coefficient, characterizing the strength stability margin, based on the voxel density defects, microseismic event frequencies, equivalent compressive strength, and actual coal pillar load; introduces an improved local mine stiffness theory, using the stiffness ratio of the system's equivalent stiffness to the coal pillar's shear stiffness as a parameter characterizing the coal pillar's stiffness stability margin; and judges the stability of end-face mining coal pillars based on the strength-stiffness dual criterion constructed from the coal pillar stability coefficient and stiffness ratio.

[0017] This invention enables non-contact imaging of internal density defects. By coupling voxel density defects, microseismic event frequency, equivalent compressive strength of coal pillar, and actual coal pillar load, it solves the blind spot of single-source monitoring and realizes non-contact, online assessment of the strength of end-side mining coal pillars. At the same time, combined with the improved local mine stiffness theory, it proposes an innovative theory for judging the stability of end-side mining coal pillars based on the strength-stiffness dual criteria composed of coal pillar stability coefficient and stiffness ratio. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a flowchart of the end-face mining coal pillar stability test method of the present invention; Figure 2 This is a schematic diagram of the functional modules of the end-face mining coal pillar stability testing device of the present invention; Figure 3 This is a schematic diagram of the structure of a computer device according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should fall within the scope of the technical content disclosed in the present invention. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0022] This invention provides an embodiment: like Figure 1 As shown, a method for testing the stability of coal pillars in end-face mining includes the following steps: S1: Multi-view cross-scanning of the coal column is performed by muon tomography to invert and reconstruct the voxel density field inside the coal column, and to determine the voxel density defects of the coal column.

[0023] The steps for determining voxel density defects in a coal pillar include: S101: Determine the object to be tested and the reconstruction space (voxel mesh).

[0024] The coal pillar and its adjacent surrounding rock are defined as a three-dimensional reconstruction region and discretized into a uniform voxel grid (each voxel is a fixed small cubic unit, and all subsequent data will fall on these voxels).

[0025] S102: Deploy detectors and establish multi-view penetration observations.

[0026] In this embodiment, the coal column is scanned from multiple angles using muon tomography. The detector used is a self-powered plastic scintillator-silicon photomultiplier flat panel detector, which is used to convert the weak light pulses generated when muons pass through the scintillator into electrical signals.

[0027] The deployment method for a self-powered plastic scintillator-silicon photomultiplier flat panel detector is as follows: A gantry is installed at the entrance of the mining chamber, and a set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors are mounted on the gantry. The set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors is set up on the outer edge of the mining chamber entrance, without entering the coal pillar body, which fully complies with the "non-contact" principle (no drilling, no burial, no damage to the coal pillar). The line of sight of the set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors passes through the coal pillar, which can obtain a sufficient number of muon events, and the gantry can be quickly assembled and disassembled.

[0028] Simultaneously, a folding telescopic track is laid at the entrance of the mining chamber. A trolley mounted on this track sends another set of self-powered plastic scintillator-silicon photomultiplier flat panel detectors into the chamber. In-chamber observation requires access to adjacent mining chambers on both sides of the same target coal pillar, with one observation line deployed in each chamber. Four self-powered plastic scintillator-silicon photomultiplier flat panel detectors are staggered along each observation line. These detectors are pre-installed at preset angles and positions on a plate-like structure connected to the front of the trolley, ensuring no mechanical contact with the coal pillar sidewall. Each detector has an effective area of ​​approximately 0.8 m², aligned with the coal pillar at a designed effective fixed angle (approximately 45°). Adjacent detectors maintain a preset baseline and angle, forming a "cross-fan-shaped line of sight," and are scanned from multiple angles for 3–5 hours.

[0029] The relative positions and attitudes of the self-powered plastic scintillator-silicon photomultiplier plate detectors on the gantry and the self-powered plastic scintillator-silicon photomultiplier plate detectors inside the chamber are pre-calibrated so that the effective line-of-sight cone of the self-powered plastic scintillator-silicon photomultiplier plate detectors on the gantry and the self-powered plastic scintillator-silicon photomultiplier plate detectors inside the chamber together form a detector array of "chamber entrance-deep coal pillar", and its effective penetration path covers the entire target coal pillar.

[0030] S103: Collect muon events and reconstruct the incident and exit trajectories (muon paths) for each muon event.

[0031] A muon event includes: the incident trajectory of a muon entering a self-powered plastic scintillator-silicon photomultiplier flat panel detector; the exit trajectory of a muon leaving the detector; and related timestamps, channel IDs, scattering angles, attenuation defects, etc. In other words, each time a cosmic ray muon passes through the detector array and is simultaneously recorded at both the entrance and exit, it constitutes a muon event.

[0032] S104: Extract two types of key information from muon events and convert the muon events into observations that can be used for chromatography.

[0033] For each time window Two key types of information are extracted from muon events: 1. Decaying deficit: the reduction in the number of coal pillars crossed from a certain perspective relative to the clearing field or prior (reflecting the trend of mass thickness crossed); where the clearing field is the baseline measurement without the object to be measured, and the prior is the known information constraint introduced in the inversion. 2. Scattering angle: large-angle scattering events are more likely to correspond to inhomogeneous structures such as internal cracks and cavities. (Fluid deficit + scattering angle are used as the two types of data for reconstruction input).

[0034] S105: Use PoCA (Approximate Point Method) to locate the scattering information to a spatial voxel.

[0035] For each muon event, the closest point between the incident trajectory and the outgoing trajectory is calculated, and this point is taken as the most likely main scattering location; then, a cluster of voxels near this point is weighted to generate an event-level weighted voxel cloud.

[0036] S106: Problems related to assembling geometric relationships and reconstructing observation data.

[0037] The system's geometric relationship matrix is ​​formed by combining the overlap relationships (overlap length, weight) between each muon path and voxels, and the observation vector is formed by combining the flux deficit and scattering angle. Simultaneously, the event-level weights corresponding to the voxel clouds of PoCA are incorporated into the geometric or observation weights, making the reconstruction more sensitive to "small defects." The event-level weights of PoCA serve as input correction terms for subsequent SART (Simultaneous Algebraic Reconstruction Technique), and in subsequent iterative updates, they not only depend on the flux deficit but also consider local weighting of the scattering angle. This approach leverages the rapid localization capability of PoCA while preserving the global consistency of SART, achieving a complementary effect.

[0038] S107: Iterative reconstruction using SART or PoCA-SART (Approximate Point Method - Synchronous Algebraic Reconstruction Technique) to obtain the time window. Voxel density estimates obtained from reconstruction .

[0039] Input the "observation vector + system geometric relationship matrix" from S106 into SART or PoCA-SART iterations to make the prediction results gradually approximate the actual observations and converge, outputting the three-dimensional voxel parameter field inside the coal pillar. Here, the three-dimensional voxel parameter field can be taken as the time window. Voxel density estimates obtained from reconstruction .

[0040] S108: Establish a benchmark reference.

[0041] In engineering practice, an initial reference is needed: typically, the voxel reference density reconstructed at the reference time is used. This is used for subsequent rolling comparisons; the baseline time refers to the time of the first round of chromatography.

[0042] S109: Define voxel density defects The density field is transformed into a damage or defect field.

[0043] When both the voxel reference density reconstructed at the baseline time are available (Baseline scan) and time window Voxel density estimates obtained from reconstruction (Current time window scan) allows the density field to be converted into a damage or defect field. The expression for voxel density defects is: In the formula, This is for reconstructing voxel units within the region. The intuitive interpretation of the above expression is: if cracks, voids, or loosening occur within a voxel, it usually manifests as a decrease in the estimated voxel density at the current moment.

[0044] Voxel density defects It is not a one-dimensional number, but a three-dimensional distribution field, which is suitable for key area identification; it also has a time dimension, which allows the network to capture early signs of defect expansion or acceleration.

[0045] S2: Obtain the frequency of microseismic events on the slope steps above the coal pillar.

[0046] In this embodiment, multiple three-component seismographs are installed on the slope steps above the coal pillar by excavating shallow holes or placing mortar bases, and are leveled and oriented to avoid mechanical seismic sources and strong radio frequency interference. The three-component seismographs are used to acquire the frequency of the microseismic events, and distributed vibration fiber optic sensors are used in conjunction to remotely pick up microseismic events.

[0047] The specific functions of a three-component seismograph are as follows: 1. The propagation of microcracks induced by mining disturbance will turn into microseismic events. The three-component seismograph can distinguish between P-waves (longitudinal waves) and S-waves (transverse waves), and pick up and locate microseismic events through polarization analysis.

[0048] 2. The three-component seismograph array is set up and integrates a 24-bit low-noise front end, with a detection threshold that can reach the micro / micro seismic level, forming a complementary coverage with the distributed vibration fiber optic sensor.

[0049] S3: Obtain coal strength parameters through indoor rock compression tests. Subtract the coal strength parameters from the coal pillar size parameters using the Hoek-Brown criterion to obtain the equivalent compressive strength of the coal pillar. This step is existing technology and will not be described in detail here.

[0050] S4: Obtain the actual coal pillar load through the subordinate area theory and the effective bearing area of ​​the coal pillar overburden load. This step is existing technology and will not be elaborated here.

[0051] S5: The voxel density defects, microseismic event frequency, equivalent compressive strength of the coal pillar, and actual coal pillar load are input into a GNN-Transformer (Graph Neural Network-Pure Attention Mechanism Deep Learning Network) fusion network to obtain the coal pillar stability coefficient, which characterizes the strength stability margin of the coal pillar. In this fusion network, the role of voxel density defects is to provide evidence of the deterioration of the internal structure of the coal pillar and determine the spatial source of risk; the microseismic event frequency provides the fracturing activity. The two, together with the equivalent compressive strength and actual coal pillar load, jointly determine the magnitude and level of the coal pillar stability coefficient.

[0052] The expression for the stability coefficient of the coal pillar is: In the formula, The stability coefficient of the coal pillar; The equivalent compressive strength of the coal pillar; This represents the actual coal pillar load. This is a voxel density defect; This is the microseismic attenuation factor; Frequency of microseismic events; It is a natural constant.

[0053] In the formula, the microseismic attenuation factor is a pre-calibrated value. The process of obtaining the equivalent compressive strength of the coal pillar and the actual coal pillar load are existing technologies and will not be described in detail here.

[0054] The GNN-Transformer fusion network combines voxel density defects, microseismic event frequencies, and other data into a multimodal graph, transmits messages on the graph, and uses self-attention to create a framework for cross-domain or global aggregation, emphasizing the fusion of "physical priors + multi-field features" and online reasoning capabilities.

[0055] S6: Introduce an improved local mine stiffness theory, using the stiffness ratio of the system's equivalent stiffness to the coal pillar's shear stiffness as a parameter characterizing the coal pillar's stiffness stability margin.

[0056] The expression for stiffness ratio is: In the formula, Stiffness ratio; For the shear stiffness of the coal pillar; In response to the situation; The system's equivalent stiffness is defined as follows: when the stiffness ratio is greater than 1, the system is considered stiffly stable; when the stiffness ratio is less than or equal to 1, the shear stiffness of the coal pillar is insufficient to provide reaction force-displacement balance, and the system is considered stiffly unstable.

[0057] The improved local mine stiffness theory is existing technology. The calculation methods and formulas for coal pillar shear stiffness and system equivalent stiffness are also existing technologies and will not be described in detail here.

[0058] S7: The stability of the end-face mining coal pillar is judged based on the strength-stiffness dual criterion composed of the coal pillar stability coefficient and stiffness ratio.

[0059] In this embodiment, the logic for judging the stability of the end-face mining coal pillar based on the strength-stiffness dual criterion composed of the coal pillar stability coefficient and stiffness ratio is as follows: When the stability coefficient of the coal pillar is greater than or equal to the preset safety threshold and the stiffness ratio is greater than 1, the coal pillar is determined to be in a stable state, and small disturbances will not trigger sudden instability.

[0060] When the stability coefficient of the coal pillar is greater than or equal to the preset safety threshold and the stiffness ratio is less than or equal to 1, the coal pillar is determined to be in a stiffness-controlled unstable state. Although the coal pillar has not reached the strength failure condition, the system is in a stiffness-controlled unstable state, and there is a risk of sudden instability triggered by small disturbances. The warning level should be raised and measures such as reinforcement or adjustment of mining pace should be taken.

[0061] When the stability coefficient of the coal pillar is less than the preset safety threshold and the stiffness ratio is greater than 1, the coal pillar is determined to be in a strength-controlled unstable state. The coal pillar is in a progressive damage stage with insufficient strength. It may still maintain quasi-static equilibrium in the short term, but its stability will continue to decline as damage accumulates, and control measures need to be taken.

[0062] When the stability coefficient of the coal pillar is less than the preset safety threshold and the stiffness ratio is less than or equal to 1, the coal pillar is determined to be in a critical instability state, and mining is forcibly stopped or control measures are taken.

[0063] In this embodiment, the safety threshold value of the coal pillar stability coefficient is set in the range of 1.05-1.2, based on the on-site geological conditions.

[0064] like Figure 2 As shown, in a second aspect, the present invention provides a stability testing device for end-slope mining coal pillars, comprising a voxel density defect determination module, a microseismic event frequency acquisition module, an equivalent compressive strength acquisition module for the coal pillar, an actual coal pillar load acquisition module, a coal pillar stability coefficient solution module, a stiffness ratio solution module, and a coal pillar stability combination judgment module; the voxel density defect determination module is used to determine the voxel density defects of the coal pillar based on muon tomography and inversion reconstruction; the microseismic event frequency acquisition module is used to acquire the frequency of microseismic events on the slope steps above the coal pillar based on a three-component seismograph; the equivalent compressive strength acquisition module is used to acquire coal body strength parameters through indoor rock compression tests, and to convert the coal body strength parameters into Hoek-B... The equivalent compressive strength of the coal pillar is obtained by using the ROWN criterion and reducing the coal pillar size parameters; the actual coal pillar load acquisition module is used to obtain the actual coal pillar load through the dependent area theory and the effective bearing area of ​​the overlying load on the coal pillar; the coal pillar stability coefficient solution module is used to solve the coal pillar stability coefficient, which characterizes the strength stability margin of the coal pillar, based on voxel density defects, microseismic event frequency, the equivalent compressive strength of the coal pillar, and the actual coal pillar load; the stiffness ratio solution module is used to solve the stiffness ratio of the system equivalent stiffness to the coal pillar shear stiffness based on the improved local mine stiffness theory; the coal pillar stability combination judgment module is used to judge the stability of the end-face mining coal pillar based on the strength-stiffness dual criterion composed of the coal pillar stability coefficient and stiffness ratio.

[0065] like Figure 3As shown, in a third aspect, the present invention provides a computer device including a memory, a processor, an input / output interface, a communication interface, and a computer program stored in the memory and capable of running on the processor. The processor executes the computer program to implement the end-face coal pillar stability testing method. The processor, memory, and input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database, while the internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store end-face coal pillar stability test data. The input / output interface of the computer device is used for exchanging information between the processor and external devices. The communication interface of the computer device is used for communication with external terminals via a network connection.

[0066] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the implementation of the end-face mining coal pillar stability testing method described in the above embodiments. In a fifth aspect, the present invention provides a computer program product comprising a computer program, which, when executed by a processor, enables the implementation of the end-face mining coal pillar stability testing method described in the above embodiments.

[0067] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of testing the stability of a coal pillar for endwall mining, characterised by, The method comprises the following steps: performing multi-view cross scanning on the coal pillar by mu tomography, and determining the voxel density defect of the coal pillar by inverting and reconstructing the voxel density field inside the coal pillar; obtaining the microseismic event frequency of the slope step above the coal pillar; obtaining the equivalent compressive strength of the coal pillar by Hoek-Brown criterion and combining the size parameters of the coal pillar based on the coal body strength parameters obtained by the indoor rock compression test; obtaining the actual load of the coal pillar by the dependent area theory and the effective bearing area of the load above the coal pillar; solving the coal pillar stability coefficient for representing the strength stability margin of the coal pillar based on the voxel density defect, the microseismic event frequency, the equivalent compressive strength of the coal pillar and the actual load of the coal pillar; introducing the improved local mine stiffness theory to take the stiffness ratio between the system equivalent stiffness and the shear stiffness of the coal pillar as a parameter for representing the stiffness stability margin of the coal pillar; judging the stability of the coal pillar for end slope mining based on the strength-stiffness double criteria constituted by the coal pillar stability coefficient and the stiffness ratio.

2. A method of testing the stability of a coal pillar for endwall mining according to claim 1 characterised in that: The expression of the coal pillar stability coefficient is: wherein, is a coal pillar stability factor; is an equivalent compressive strength of the coal pillar; is an actual coal pillar load; is a voxel density defect; is a microseismic decay factor; is a microseismic event frequency; is a natural constant.

3. A method of testing the stability of a coal pillar for endwall mining according to claim 2, characterised in that: The logic for judging the stability of the coal pillar for end slope mining based on the strength-stiffness double criteria constituted by the coal pillar stability coefficient and the stiffness ratio is: when the coal pillar stability coefficient is greater than or equal to the preset safety threshold and the stiffness ratio is greater than 1, it is determined that the coal pillar is in a stable state; when the coal pillar stability coefficient is greater than or equal to the preset safety threshold and the stiffness ratio is less than or equal to 1, it is determined that the coal pillar is in a stiffness-controlled unstable state; when the coal pillar stability coefficient is less than the preset safety threshold and the stiffness ratio is greater than 1, it is determined that the coal pillar is in a strength-controlled unstable state; when the coal pillar stability coefficient is less than the preset safety threshold and the stiffness ratio is less than or equal to 1, it is determined that the coal pillar is in a critical unstable state, and forced measures such as stopping mining or control measures are taken.

4. A method of testing the stability of a coal pillar for endwall mining according to claim 1 characterised in that: The detector used for the multi-view cross scanning of the coal pillar by mu tomography is a self-powered plastic flash-silicon photomultiplier flat panel detector; a gantry is arranged at the mouth of the mining chamber, and a group of self-powered plastic flash-silicon photomultiplier flat panel detectors are installed on the gantry; at the same time, a folding telescopic track is laid at the mouth of the mining chamber, and another group of self-powered plastic flash-silicon photomultiplier flat panel detectors are sent to the preset position inside the mining chamber through the trolley arranged on the folding telescopic track.

5. The coal pillar stability test method for end slope mining according to claim 1, characterized in that: the voxel density defect of the coal pillar is obtained by PoCA-SART inversion and reconstruction of the voxel density field inside the coal pillar, and the density field is converted into a defect field; the expression of the voxel density defect of the coal pillar is: In the formula, is a voxel density defect; is a voxel unit within the reconstruction region; is a voxel reference density obtained by reconstruction at the reference time; is a time window is a voxel density estimate obtained by reconstruction at the reference time.

6. A method of testing the stability of a coal pillar for endwall mining according to claim 1 characterised in that: a plurality of three-component seismographs are installed on the slope step above the coal pillar in the form of hole digging or mortar pedestal placement, and are leveled and oriented, and the three-component seismographs are used to obtain the microseismic event frequency, and a distributed vibration optical fiber sensor is used to remotely pick up microseismic events.

7. A coal pillar stability test device for end slope mining, which is used to implement the coal pillar stability test method for end slope mining according to any one of claims 1 to 6. The method comprises a voxel density defect determination module, a microseismic event frequency acquisition module, an equivalent compressive strength of the coal pillar acquisition module, an actual coal pillar load acquisition module, a coal pillar stability coefficient solving module, a stiffness ratio solving module, and a coal pillar stability combination determination module. The voxel density defect determination module is configured to determine the voxel density defect of the coal pillar based on mu tomography and inversion reconstruction. The microseismic event frequency acquisition module is configured to acquire the microseismic event frequency of the slope step above the coal pillar based on a three-component seismograph. The equivalent compressive strength of the coal pillar acquisition module is configured to acquire the coal body strength parameter through an indoor rock compression test, and obtain the equivalent compressive strength of the coal pillar by reducing the coal body strength parameter through the Hoek-Brown criterion and in combination with the coal pillar size parameter. The actual coal pillar load acquisition module is configured to acquire the actual coal pillar load through the dependent area theory and the effective bearing area of the overlying load of the coal pillar. The coal pillar stability coefficient solving module is configured to solve the coal pillar stability coefficient for representing the strength stability margin of the coal pillar based on the voxel density defect, the microseismic event frequency, the equivalent compressive strength of the coal pillar, and the actual coal pillar load. The stiffness ratio solving module is configured to solve the stiffness ratio of the system equivalent stiffness and the shear stiffness of the coal pillar based on the improved local mine stiffness theory. The coal pillar stability combination determination module is configured to determine the stability of the end slope mining coal pillar based on the strength-stiffness dual criterion constituted by the coal pillar stability coefficient and the stiffness ratio.

8. A computer device comprising a memory, a processor, and a computer program stored on the memory and capable of running on the processor, characterized in that: The processor executes the computer program to implement the end slope mining coal pillar stability test method according to any one of claims 1-6.

9. A computer readable storage medium storing a computer program, characterized in that: The computer program is executed by the processor to implement the end slope mining coal pillar stability test method according to any one of claims 1-6.

10. A computer program product comprising a computer program, characterized in that: The computer program is executed by the processor to implement the end slope mining coal pillar stability test method according to any one of claims 1-6.

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