A method and system for determining the vertical position of a low-position key layer in a coal mining face

Abstract

This application proposes a method and system for determining the vertical strata of key strata in low-lying areas of a coal mining face. The method includes: using borehole stress gauges arranged in coal pillars at predetermined locations in the auxiliary haulage roadway of the working face to acquire in real time the stress of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; determining the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; using a microseismic monitoring system both above and below ground to monitor in real time the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period; and determining the vertical strata of key strata in low-lying areas of the working face based on the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights. The scheme proposed in this application can accurately and quantitatively determine the strata of key strata in low-lying areas.

Description

Technical Field

[0001] This application relates to the field of coal mining technology, and in particular to a method and system for determining the vertical strata of key low-level strata in a coal mining face. Background Technology

[0002] The fracturing of low-to-medium level key strata is a major cause of sudden surges in mine pressure at the working face. Existing coal mining theories define key strata as those that control the activity of local or even all strata above the working face, with the former called sub-key strata and the latter main key strata. There may be multiple sub-key strata in the overlying strata, but only one main key strata. The roof is the lower sub-key stratum that influences the mine pressure manifestation at the working face. Furthermore, based on the vertical distance of the key strata from the coal seam, those closest to the coal seam are designated as low-level key strata. As the vertical distance increases, the overlying layers of low-level key strata are successively designated as intermediate-level and high-level key strata. The fracturing of low-to-medium level key strata is the main cause of sudden surges in mine pressure at the working face. The vertical height of the key strata has a negative correlation with the degree of influence on mine pressure manifestation at the working face; the fracturing and instability of low-to-medium level key strata have a more direct and significant impact on the pressure exerted on the working face. The reason is that, after the rock strata between the key layer and the working face fracture, they possess a certain load-bearing structure, capable of absorbing and dispersing the fracture stress and energy of the "key layer," ultimately weakening its impact on the vertical load on the working face. Therefore, as the vertical distance between the "key layer" and the coal seam increases, and the number and thickness of fractured rock strata increase, the impact of the "key layer" fracture on the rate of increase and peak value of the stope support pressure will weaken. Therefore, compared to "high-level key layers," "mid-to-low-level key layers" have a more direct and significant impact on the manifestation of mining pressure at the working face, and accurate identification of their spatial strata is a necessary condition for precise and efficient control of mining pressure in the stope.

[0003] Current technologies cannot accurately and comprehensively obtain vertical stratigraphic information of "mid-to-low-level key strata." Existing methods for identifying and determining "key strata" include theoretical analysis, numerical calculation, and borehole displacement gauge measurement. However, the reliability of theoretical analysis and numerical calculations is reduced due to the difficulty in accurately obtaining the physical and mechanical parameters of each roof stratum. Borehole displacement gauge measurement, which involves deploying displacement sensors in each roof stratum and capturing and analyzing the collapse and subsidence characteristics of each stratum during mining, identifies the spatial distribution of "key strata." While this method has relatively good reliability, it suffers from high construction costs, long construction periods, limited visibility (based on a single borehole), and inability to reflect regional strata movement patterns, making it difficult to efficiently and quickly obtain the regional distribution characteristics of "key strata." In summary, the lack of a reliable quantitative method for determining "key strata" severely restricts roof strata control and mine pressure regulation in coal mining faces. Therefore, there is an urgent need to propose a scheme that can accurately and quantitatively determine the location of mid-to-low-level key strata. Summary of the Invention

[0004] This application provides a method and system for determining the vertical strata of key strata in low-level coal mining faces, so as to at least solve the technical problem that the lack of a reliable quantitative determination scheme for "key strata" in the existing technology has seriously restricted the control of roof strata and mine pressure regulation in coal mining faces.

[0005] The first aspect of this application proposes a method for determining the vertical strata of a low-lying key stratum in a coal mining face, the method comprising:

[0006] The stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress are obtained in real time by using borehole stress gauges arranged in coal pillars at preset positions in the auxiliary haulage roadway of the working face.

[0007] The mining-affected area and mining-affected period are determined based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress.

[0008] The microseismic energy at the preset location during the mining process is monitored in real time using a surface and underground microseismic monitoring system, and the microseismic energy at different heights in the mining-affected area at different times during the mining-affected period is also monitored.

[0009] The vertical strata of the low-level key strata in the coal mining face are determined based on the microseismic event energy at the preset location and the microseismic energy at different heights.

[0010] Preferably, the determination of the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress includes:

[0011] Based on the stresses of the surrounding rock at the preset location during the mining process and the distance between the preset location and the working face, a stress curve of the auxiliary transport roadway coal pillar during the mining period is constructed.

[0012] The mining-affected area and mining-affected period are determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress.

[0013] Furthermore, determining the vertical stratum of the low-level key strata in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations includes:

[0014] The energy accumulation area is determined based on the energy of microseismic events at the preset locations during the mining process;

[0015] The sum of the energy of microseismic events at different heights from the coal seam during the mining-affected period was determined.

[0016] The vertical height of the energy accumulation area is determined based on the sum of the microseismic events corresponding to the different height positions.

[0017] The vertical height of the energy accumulation area is taken as the vertical stratum of the low-level key layer in the coal mining face.

[0018] Furthermore, the step of constructing the stress curve of the auxiliary haulage roadway coal pillar during mining based on the stresses of the surrounding rock at the preset position during the mining process and the distance between the preset position and the working face includes:

[0019] Using the distances between the preset position and the working face during the mining process as the X-axis and the stresses of the surrounding rock at the preset position during the mining process as the Y-axis, a stress curve of the auxiliary transport roadway coal pillar is constructed during the mining period.

[0020] Furthermore, the determination of the mining-affected area and mining-affected period based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress includes:

[0021] The area before the impact of mining and where the stress change amplitude is less than the first threshold is defined as the area before the impact of mining.

[0022] The region affected by mining and whose stress change amplitude is less than the first threshold is defined as the region affected by mining.

[0023] The distance range between the preset position and the working face in the stress curve of the auxiliary transport roadway coal pillar during the mining period, between the region before and after the mining impact, is taken as the mining impact area.

[0024] Based on the stress curve of the auxiliary transport roadway coal pillar during the mining period, the stress corresponding to the maximum distance and the stress corresponding to the minimum distance within the mining-affected area are obtained;

[0025] The time corresponding to the stress at the maximum distance is taken as the start time of the mining-affected period, and the time corresponding to the stress at the minimum distance is taken as the end time of the mining-affected period.

[0026] The mining impact period is defined by the start time and the end time of the mining impact period.

[0027] Furthermore, determining the energy accumulation area based on the microseismic event energy at the preset location during mining includes:

[0028] The distance between the preset location and the working face when acquiring the energy of each microseismic event at the preset location during the mining process;

[0029] The energy of each microseismic event at the preset location during the mining process is sorted from left to right in ascending order of distance between the preset location and the working face to form a microseismic event energy sequence.

[0030] Find the maximum energy value of the microseismic event in the microseismic event energy sequence, then determine the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface, and take the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface as the starting position of the energy accumulation area;

[0031] Calculate the difference between the maximum energy value of the microseismic event in the microseismic event energy sequence and the energy value of the i-th microseismic event to its right. When the difference is less than or equal to a second threshold, calculate the difference between the energy value of the i-th microseismic event to its right and the energy value of the (i-1)-th microseismic event to its right, until the difference is greater than the second threshold. Take the distance between the preset position corresponding to the energy value of the i-th microseismic event and the working surface as the end position of the energy accumulation area, where i is equal to 1, 2, 3, ..., 1 in sequence.

[0032] The energy gathering region is defined as the starting and ending positions of the energy gathering region.

[0033] Furthermore, determining the vertical height of the energy accumulation area based on the sum of the microseismic event energies corresponding to the different height positions includes:

[0034] The height position corresponding to the maximum sum of microseismic event energies at each different height position is selected.

[0035] The vertical height of the energy accumulation area is determined based on a preset floating threshold and the height position corresponding to the maximum sum of the energy of the microseismic events.

[0036] Furthermore, the method also includes:

[0037] The stress acceleration increase region is determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period.

[0038] The spatial overlap coefficient is determined based on the stress acceleration expansion region and the energy accumulation region.

[0039] When the spatial overlap coefficient is greater than 90%, the vertical stratum position of the low-level key layer in the coal mining face is determined to be correct; otherwise, the vertical stratum position of the low-level key layer in the coal mining face is determined to be incorrect.

[0040] The second aspect of this application provides a system for determining the vertical stratigraphic position of a low-lying key stratum in a coal mining face, comprising:

[0041] The acquisition module is used to acquire in real time the stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress by using the borehole stress gauge arranged in the coal pillar at the preset position in the auxiliary haulage roadway of the working face.

[0042] The first determining module is used to determine the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress.

[0043] The monitoring module is used to monitor the energy of microseismic events at the preset location during the mining process and to monitor the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period using the surface and underground microseismic monitoring system.

[0044] The second determining module is used to determine the vertical stratum of the low-level key layer in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations.

[0045] A third aspect of this application provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the method described in the first aspect.

[0046] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects:

[0047] This application proposes a method and system for determining the vertical strata of key strata in the middle and lower reaches of a coal mining face. The method includes: using borehole stress gauges arranged in coal pillars at predetermined locations in the auxiliary haulage roadway of the working face to acquire in real time the stress of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; determining the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; using a microseismic monitoring system both above and below ground to monitor the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period; and determining the vertical strata of key strata in the middle and lower reaches of the coal mining face based on the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights. The technical solution proposed in this application can accurately and quantitatively determine the strata of key strata in the middle and lower reaches.

[0048] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0049] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0050] Figure 1 This is a flowchart illustrating a method for determining the vertical stratum of a low-lying key stratum in a coal mining face, according to an embodiment of this application.

[0051] Figure 2 This is a schematic diagram of a borehole stress gauge arrangement according to an embodiment of this application;

[0052] Figure 3 This is a schematic diagram of the stress curve of the auxiliary transport roadway coal pillar during mining, according to an embodiment of this application.

[0053] Figure 4 This is a schematic diagram of a surface and underground microseismic monitoring system provided according to an embodiment of this application at the working face;

[0054] Figure 5 This is a schematic diagram of the directional energy distribution characteristics provided according to an embodiment of this application;

[0055] Figure 6 This is a schematic diagram of vertical energy distribution characteristics according to an embodiment of this application;

[0056] Figure 7 This is a structural diagram of a system for determining the vertical stratum of a low-level key stratum in a coal mining face, according to an embodiment of this application. Detailed Implementation

[0057] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0058] This application proposes a method and system for determining the vertical strata of key strata in the middle and lower reaches of a coal mining face. The method includes: using borehole stress gauges arranged in coal pillars at predetermined locations in the auxiliary haulage roadway of the working face to acquire in real time the stress of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; determining the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the predetermined location, the distance between the predetermined location and the working face, and the time corresponding to each stress during mining; using a microseismic monitoring system both above and below ground to monitor the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period; and determining the vertical strata of key strata in the middle and lower reaches of the coal mining face based on the energy of microseismic events at the predetermined location and the energy of microseismic events at different heights. The technical solution proposed in this application can accurately and quantitatively determine the strata of key strata in the middle and lower reaches.

[0059] The following description, with reference to the accompanying drawings, illustrates a method and system for determining the vertical strata of a low-lying key stratum in a coal mining face, according to an embodiment of this application.

[0060] Example 1

[0061] Figure 1 This is a flowchart illustrating a method for determining the vertical stratigraphic position of a low-lying key stratum in a coal mining face, according to an embodiment of this application. Figure 1 As shown, the method includes:

[0062] It should be noted that the roof strata within a range of 4 times the mining thickness above the coal seam are considered "low-lying strata," while those within a range of 4-8 times the mining thickness are considered "intermediate strata." Extensive practical experience shows that when these "intermediate-low-lying key strata" fracture, it inevitably triggers the rotation and subsidence of a larger area of ​​overlying strata, a surge in surrounding rock stress in the mining area, and a significant release of fracture energy from the roof strata. Therefore, continuous monitoring of "surrounding rock stress in the mining area + fracture energy of the roof overlying strata" can be used to conduct a correlation analysis of vertical strata fracture energy activity and changes in surrounding rock stress in the mining area. Ultimately, this allows for accurate and reliable identification and determination of the vertical strata of the "intermediate-low-lying key strata" that have a significant impact on mining pressure in the mining area.

[0063] Step 1: Use borehole stress gauges placed in coal pillars at preset positions in the auxiliary haulage roadway of the working face to obtain in real time the stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress during the mining process.

[0064] It should be noted that, as Figure 2 As shown, borehole stress gauges are installed in the coal pillar of the auxiliary haulage roadway of the working face to continuously monitor the stress of the coal pillar throughout the entire process affected by the mining activities of the working face.

[0065] Step 2: Determine the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress.

[0066] In this embodiment of the disclosure, step 2 specifically includes:

[0067] 2.1 Based on the stresses of the surrounding rock at the preset location during the mining process and the distance between the preset location and the working face, construct the stress curve of the auxiliary transport roadway coal pillar during the mining period;

[0068] In the embodiments disclosed herein, such as Figure 3 As shown, the stress curve of the auxiliary transport roadway coal pillar during mining is constructed by taking the distance between the preset position and the working face during mining as the X-axis and the stress of the surrounding rock at the preset position during mining as the Y-axis.

[0069] 2.2 Determine the mining-affected area and mining-affected period based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress.

[0070] In this embodiment of the disclosure, determining the mining-affected area and mining-affected period based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress includes:

[0071] The area before the impact of mining and where the stress change amplitude is less than a first threshold is defined as the area before the impact of mining, wherein the first threshold can be five percent.

[0072] The region affected by mining and whose stress change amplitude is less than the first threshold is defined as the region affected by mining.

[0073] The distance range between the preset position and the working face in the stress curve of the auxiliary transport roadway coal pillar during the mining period, between the region before and after the mining impact, is taken as the mining impact area.

[0074] Based on the stress curve of the auxiliary transport roadway coal pillar during the mining period, the stress corresponding to the maximum distance and the stress corresponding to the minimum distance within the mining-affected area are obtained;

[0075] The time corresponding to the stress at the maximum distance is taken as the start time of the mining-affected period, and the time corresponding to the stress at the minimum distance is taken as the end time of the mining-affected period.

[0076] The mining impact period is defined by the start time and the end time of the mining impact period.

[0077] It should be noted that by monitoring the stress in the coal pillar, the evolution law of the stress in the coal pillar during the working face advance can be obtained, such as... Figure 3 As shown.

[0078] According to general patterns, the changes in coal pillar stress monitoring results can be categorized into three stages: Stage 1, before mining impact (stress change amplitude is less than 5% based on the initial coal pillar stress value); Stage 2, during mining impact (stress change amplitude is greater than or equal to 5% based on Stage 1); and Stage 3, after mining impact (stress amplitude is less than 5% based on Stage 2, gradually stabilizing). Within Stage 2, the "during mining impact" stage, the coal pillar stress change, based on the monitoring curve trend, includes both a "slow rise" and an "accelerated increase." Based on the movement pattern of the "key stratum" after fracture and its impact on mine pressure, it is preliminarily determined that the "accelerated increase" stage is strongly correlated with the fracture of the "low-to-medium level key stratum."

[0079] Among them, for Figure 3 The stress curves of the coal pillars shown are the stress curves of the coal pillars in the auxiliary transport roadway during mining. The following points need to be added: A. The position and time of "starting to rise" are X1 and t1, respectively; B. The position and time of "accelerated rise" are X2 and t2, respectively; C. The position and time of "stable position" are X3 and t3, respectively.

[0080] Step 3: Use the surface and underground microseismic monitoring system to monitor the energy of microseismic events at the preset location during the mining process and monitor the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period;

[0081] It should be noted that, as Figure 4 As shown, the surface and underground microseismic monitoring system includes: a surface ARP monitoring station, a downhole seismic pickup, and a downhole probe; the surface and underground microseismic monitoring system is used to perform three-dimensional monitoring of overburden activity.

[0082] Step 4: Determine the vertical stratum of the low-level key layer in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations.

[0083] In this embodiment of the disclosure, step 4 specifically includes:

[0084] 4.1 Determine the energy accumulation area based on the microseismic event energy at the preset location during the mining process;

[0085] In the embodiments disclosed herein, such as Figure 5 As shown, determining the energy accumulation area based on the microseismic event energy at the preset location during mining includes:

[0086] The distance between the preset location and the working face when acquiring the energy of each microseismic event at the preset location during the mining process;

[0087] The energy of each microseismic event at the preset location during the mining process is sorted from left to right in ascending order of distance between the preset location and the working face to form a microseismic event energy sequence.

[0088] Find the maximum energy value of the microseismic event in the microseismic event energy sequence, then determine the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface, and take the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface as the starting position of the energy accumulation area;

[0089] Calculate the difference between the maximum energy value of the microseismic event in the microseismic event energy sequence and the energy value of the i-th microseismic event to its right. When the difference is less than or equal to a second threshold, calculate the difference between the energy value of the i-th microseismic event to its right and the energy value of the (i-1)-th microseismic event to its right, until the difference is greater than the second threshold. Take the distance between the preset position corresponding to the energy value of the i-th microseismic event and the working surface as the end position of the energy accumulation area, where i is equal to 1, 2, 3, ..., 1 in sequence.

[0090] The energy gathering region is defined as the starting and ending positions of the energy gathering region.

[0091] 4.2 Determine the sum of the energy of microseismic events at different heights from the coal seam during the mining-affected period;

[0092] 4.3 Determine the vertical height of the energy accumulation area based on the sum of the microseismic event energies corresponding to the different height locations;

[0093] In the embodiments disclosed herein, such as Figure 6 As shown, determining the vertical height of the energy accumulation area based on the sum of the microseismic event energies corresponding to the different height positions includes:

[0094] The height position corresponding to the maximum sum of microseismic event energies at each different height position is selected.

[0095] The vertical height of the energy accumulation area is determined based on a preset floating threshold and the height position corresponding to the maximum sum of the energy of the microseismic events.

[0096] Wherein, the vertical height refers to the vertical height; the floating threshold is determined based on the microseismic monitoring accuracy, for example: the microseismic monitoring accuracy is approximately 20 meters. Figure 6 The energy concentration zone is 50 meters, and the fluctuation range is 10 meters, which is the fluctuation threshold, so it is 40-60 meters.

[0097] 4.4 The vertical height of the energy accumulation area is taken as the vertical stratum of the low-level key layer in the coal mining face.

[0098] It should be noted that, according to Figure 3 The time nodes t1→t3 of the entire stress evolution process of the A→C coal pillar were used to screen and obtain the vertical and directional spatial distribution characteristics of the roof overburden fracture energy during the stress evolution process, such as... Figure 5 and Figure 6 As shown. Based on the movement and energy release patterns after the "key layer" fractures, it is preliminarily determined that there is a strong correlation between the vertical and horizontal "energy accumulation zones" and the fracture of the "middle and low-level key layers".

[0099] It should be noted that, Figure 5 and Figure 6 The spatial distribution characteristics of energy are the cross-sectional projection results of the "energy release process" of rock strata fracturing within the same range on the strike and vertical spatial profiles. The "energy accumulation zone" involved is the result of "energy accumulation release" caused by rock strata fracturing within the same range of objects at the same time period.

[0100] In this embodiment of the disclosure, the method further includes:

[0101] The stress acceleration increase region is determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period.

[0102] The spatial overlap coefficient is determined based on the stress acceleration expansion region and the energy accumulation region.

[0103] When the spatial overlap coefficient is greater than 90%, the vertical stratum position of the low-level key layer in the coal mining face is determined to be correct; otherwise, the vertical stratum position of the low-level key layer in the coal mining face is determined to be incorrect.

[0104] It should be noted that... Figure 3 The beginning and end positions of the "accelerated increase" stage of coal pillar stress, which is strongly correlated with the failure of the "key layer," and... Figure 5 The spatial overlap coefficient φ is compared between the start and end positions of the "energy distance" trajectories of the top plate fracture that are strongly correlated with the "critical layer" fracture. When the overlap coefficient φ is high (greater than 90%), it can be considered as... Figure 6 The "energy accumulation vertical height H1-H2" is the distribution layer of the "middle and low key layer".

[0105] Among them, the spatial overlap coefficient of the characteristics of "energy accumulation" during roof fracture and "accelerated increase" in coal pillar stress is... The calculation formula is as follows:

[0106]

[0107] In the formula, Y1 is the starting position of the accumulation of "top plate fracture energy", and Y2 is the ending position of the accumulation of "top plate fracture energy".

[0108] This marks the starting point of the accelerated increase in "coal pillar stress". This marks the end of the accelerated increase in "coal pillar stress".

[0109] It should be noted that the "key stratum" refers to the strata whose activity locally or even extends to the entire surface of the overlying rock layer in the mining area plays a controlling role. Furthermore, the failure and instability of the "middle and low-level key strata" have a more direct and significant impact on the working face and mining pressure. Therefore, accurate vertical stratigraphic measurements of the "middle and low-level key strata" are of significant practical importance for the development and application of relevant theories on "key strata" and for the control of mining pressure in the mining area. This application also has the following advantages:

[0110] 1. Based on the essential spatiotemporal correlation between the failure of the "mid-to-low key strata" and the pressure from the working face, the conclusions are scientific and highly reliable. Based on the fundamental causal relationship that the failure of the "mid-to-low key strata" leads to further failure and subsidence in the overlying layer of the working face, ultimately inducing a surge in coal pillar stress, a systematic approach using microseismic monitoring and coal pillar stress monitoring techniques is employed. By examining the spatial correlation between roof failure energy and pressure from the working face, the vertical distribution of the "mid-to-low key strata" can be accurately and scientifically determined.

[0111] 2. The equipment boasts low operating costs and high reusability, facilitating research on the mechanisms of surrounding rock control and the movement of "key strata" in mining areas, as well as the implementation of remediation projects. Microseismic and coal pillar stress monitoring equipment are the main inputs in the implementation of this invention. These monitoring systems do not experience direct wear and tear during data acquisition and can be reused as the working face moves. Therefore, the implementation of this invention features high equipment reusability, low operating costs, and ease of large-scale, repeated use in mines, thereby contributing to a comprehensive understanding of the location of "mid-to-low-level key strata" in different geological blocks and at different mining stages of the same working face.

[0112] In summary, the method for determining the vertical strata of key strata in the middle and lower levels of a coal mining face proposed in this embodiment can accurately and quantitatively determine the strata of key strata in the middle and lower levels.

[0113] Example 2

[0114] Figure 7 This is a structural diagram of a vertical stratum determination system for low-level key strata in a coal mining face, according to an embodiment of this application. Figure 7 As shown, the system includes:

[0115] The acquisition module 100 is used to acquire in real time the stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress during the mining process using a borehole stress gauge arranged in a coal pillar at a preset position in the auxiliary haulage roadway of the working face.

[0116] The first determining module 200 is used to determine the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset position during the mining process, the distance between the preset position and the working face, and the time corresponding to each stress.

[0117] The monitoring module 300 is used to monitor the energy of microseismic events at the preset location during the mining process and to monitor the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period using a surface and underground microseismic monitoring system.

[0118] The second determining module 400 is used to determine the vertical stratum of the low-level key layer in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations.

[0119] In this embodiment of the disclosure, the first determining module 200 is further configured to:

[0120] Based on the stresses of the surrounding rock at the preset location during the mining process and the distance between the preset location and the working face, a stress curve of the auxiliary transport roadway coal pillar during the mining period is constructed.

[0121] The mining-affected area and mining-affected period are determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress.

[0122] In this embodiment of the disclosure, the second determining module 400 is further configured to:

[0123] The energy accumulation area is determined based on the energy of microseismic events at the preset locations during the mining process;

[0124] The sum of the energy of microseismic events at different heights from the coal seam during the mining-affected period was determined.

[0125] The vertical height of the energy accumulation area is determined based on the sum of the microseismic events corresponding to the different height positions.

[0126] The vertical height of the energy accumulation area is taken as the vertical stratum of the low-level key layer in the coal mining face.

[0127] Furthermore, the first determining module 200 is also used for:

[0128] Using the distances between the preset position and the working face during the mining process as the X-axis and the stresses of the surrounding rock at the preset position during the mining process as the Y-axis, a stress curve of the auxiliary transport roadway coal pillar is constructed during the mining period.

[0129] Furthermore, the first determining module 200 is also used for:

[0130] The area before the impact of mining and where the stress change amplitude is less than the first threshold is defined as the area before the impact of mining.

[0131] The region affected by mining and whose stress change amplitude is less than the first threshold is defined as the region affected by mining.

[0132] The distance range between the preset position and the working face in the stress curve of the auxiliary transport roadway coal pillar during the mining period, between the region before and after the mining impact, is taken as the mining impact area.

[0133] Based on the stress curve of the auxiliary transport roadway coal pillar during the mining period, the stress corresponding to the maximum distance and the stress corresponding to the minimum distance within the mining-affected area are obtained;

[0134] The time corresponding to the stress at the maximum distance is taken as the start time of the mining-affected period, and the time corresponding to the stress at the minimum distance is taken as the end time of the mining-affected period.

[0135] The mining impact period is defined by the start time and the end time of the mining impact period.

[0136] Furthermore, the second determining module 400 is also used for:

[0137] The distance between the preset location and the working face when acquiring the energy of each microseismic event at the preset location during the mining process;

[0138] The energy of each microseismic event at the preset location during the mining process is sorted from left to right in ascending order of distance between the preset location and the working face to form a microseismic event energy sequence.

[0139] Find the maximum energy value of the microseismic event in the microseismic event energy sequence, then determine the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface, and take the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface as the starting position of the energy accumulation area;

[0140] Calculate the difference between the maximum energy value of the microseismic event in the microseismic event energy sequence and the energy value of the i-th microseismic event to its right. When the difference is less than or equal to a second threshold, calculate the difference between the energy value of the i-th microseismic event to its right and the energy value of the (i-1)-th microseismic event to its right, until the difference is greater than the second threshold. Take the distance between the preset position corresponding to the energy value of the i-th microseismic event and the working surface as the end position of the energy accumulation area, where i is equal to 1, 2, 3, ..., 1 in sequence.

[0141] The energy gathering region is defined as the starting and ending positions of the energy gathering region.

[0142] Furthermore, the second determining module 400 is also used for:

[0143] The height position corresponding to the maximum sum of microseismic event energies at each different height position is selected.

[0144] The vertical height of the energy accumulation area is determined based on a preset floating threshold and the height position corresponding to the maximum sum of the energy of the microseismic events.

[0145] In this embodiment of the disclosure, the second determining module 400 is further configured to:

[0146] The stress acceleration increase region is determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period.

[0147] The spatial overlap coefficient is determined based on the stress acceleration expansion region and the energy accumulation region.

[0148] When the spatial overlap coefficient is greater than 90%, the vertical stratum position of the low-level key layer in the coal mining face is determined to be correct; otherwise, the vertical stratum position of the low-level key layer in the coal mining face is determined to be incorrect.

[0149] In summary, the vertical stratum determination system for low-to-medium key strata in coal mining faces proposed in this embodiment can accurately and quantitatively determine the stratum position of low-to-medium key strata.

[0150] Example 3

[0151] To implement the above embodiments, this disclosure also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in Embodiment 1.

[0152] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. 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.

[0153] 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 the preferred embodiments of this application 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 this application pertain.

[0154] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for determining the vertical stratigraphic position of a low-level key stratum in a coal mining face, characterized in that, The method includes: The stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress are obtained in real time by using borehole stress gauges arranged in coal pillars at preset positions in the auxiliary haulage roadway of the working face. The mining-affected area and mining-affected period are determined based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress. The microseismic energy at the preset location during the mining process is monitored in real time using a surface and underground microseismic monitoring system, and the microseismic energy at different heights in the mining-affected area at different times during the mining-affected period is also monitored. The vertical strata of the low-level key strata in the coal mining face are determined based on the microseismic event energy at the preset location and the microseismic energy at different heights.

2. The method as described in claim 1, characterized in that, The determination of the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress includes: Based on the stresses of the surrounding rock at the preset location during the mining process and the distance between the preset location and the working face, a stress curve of the auxiliary transport roadway coal pillar during the mining period is constructed. The mining-affected area and mining-affected period are determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress.

3. The method as described in claim 2, characterized in that, The step of determining the vertical stratum of the low-level key strata in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations includes: The energy accumulation area is determined based on the energy of microseismic events at the preset locations during the mining process; The sum of the energy of microseismic events at different heights from the coal seam during the mining-affected period was determined. The vertical height of the energy accumulation area is determined based on the sum of the microseismic events corresponding to the different height positions. The vertical height of the energy accumulation area is taken as the vertical stratum of the low-level key layer in the coal mining face.

4. The method as described in claim 3, characterized in that, The method of constructing the stress curve of the auxiliary haulage roadway coal pillar during mining based on the stresses of the surrounding rock at the preset position during the mining process and the distance between the preset position and the working face includes: Using the distances between the preset position and the working face during the mining process as the X-axis and the stresses of the surrounding rock at the preset position during the mining process as the Y-axis, a stress curve of the auxiliary transport roadway coal pillar is constructed during the mining period.

5. The method as described in claim 4, characterized in that, The determination of the mining-affected area and mining-affected period based on the stress curve of the auxiliary transport roadway coal pillar during the mining period and the time corresponding to each stress includes: The area before the impact of mining and where the stress change amplitude is less than the first threshold is defined as the area before the impact of mining. The region affected by mining and whose stress change amplitude is less than the first threshold is defined as the region affected by mining. The distance range between the preset position and the working face in the stress curve of the auxiliary transport roadway coal pillar during the mining period, between the region before and after the mining impact, is taken as the mining impact area. Based on the stress curve of the auxiliary transport roadway coal pillar during the mining period, the stress corresponding to the maximum distance and the stress corresponding to the minimum distance within the mining-affected area are obtained; The time corresponding to the stress at the maximum distance is taken as the start time of the mining-affected period, and the time corresponding to the stress at the minimum distance is taken as the end time of the mining-affected period. The mining impact period is defined by the start time and the end time of the mining impact period.

6. The method as described in claim 3, characterized in that, The determination of the energy accumulation area based on the microseismic event energy at the preset location during mining includes: The distance between the preset location and the working face when acquiring the energy of each microseismic event at the preset location during the mining process; The energy of each microseismic event at the preset location during the mining process is sorted from left to right in ascending order of distance between the preset location and the working face to form a microseismic event energy sequence. Find the maximum energy value of the microseismic event in the microseismic event energy sequence, then determine the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface, and take the distance between the preset position corresponding to the maximum energy value of the microseismic event and the working surface as the starting position of the energy accumulation area; Calculate the difference between the maximum energy value of the microseismic event in the microseismic event energy sequence and the energy value of the i-th microseismic event to its right. When the difference is less than or equal to a second threshold, calculate the difference between the energy value of the i-th microseismic event to its right and the energy value of the (i-1)-th microseismic event to its right, until the difference is greater than the second threshold. Take the distance between the preset position corresponding to the energy value of the i-th microseismic event and the working surface as the end position of the energy accumulation area, where i is equal to 1, 2, 3, ..., 1 in sequence. The energy gathering region is defined as the starting and ending positions of the energy gathering region.

7. The method as described in claim 3, characterized in that, Determining the vertical height of the energy accumulation area based on the sum of the microseismic event energies corresponding to the different height locations includes: The height position corresponding to the maximum sum of microseismic event energies at each different height position is selected. The vertical height of the energy accumulation area is determined based on a preset floating threshold and the height position corresponding to the maximum sum of the energy of the microseismic events.

8. The method as described in claim 7, characterized in that, The method further includes: The stress acceleration increase region is determined based on the stress curve of the auxiliary transport roadway coal pillar during the mining period. The spatial overlap coefficient is determined based on the stress acceleration expansion region and the energy accumulation region. When the spatial overlap coefficient is greater than 90%, the vertical stratum position of the low-level key layer in the coal mining face is determined to be correct; otherwise, the vertical stratum position of the low-level key layer in the coal mining face is determined to be incorrect.

9. A system for determining the vertical stratigraphic position of key low-level strata in a coal mining face, characterized in that, The system includes: The acquisition module is used to acquire in real time the stress of the surrounding rock at the preset position, the distance between the preset position and the working face, and the time corresponding to each stress by using the borehole stress gauge arranged in the coal pillar at the preset position in the auxiliary haulage roadway of the working face. The first determining module is used to determine the mining-affected area and mining-affected period based on the stresses of the surrounding rock at the preset location during the mining process, the distance between the preset location and the working face, and the time corresponding to each stress. The monitoring module is used to monitor the energy of microseismic events at the preset location during the mining process and to monitor the energy of microseismic events at different heights in the mining-affected area at different times during the mining-affected period using the surface and underground microseismic monitoring system. The second determining module is used to determine the vertical stratum of the low-level key layer in the coal mining face based on the microseismic event energy at the preset location and the microseismic energy at different height locations.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-8.

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