Coordinated mining method for deep high-stress steeply inclined coal seam group

Abstract

The invention discloses a coordinated mining method for a deep high-stress steeply-inclined coal seam group, and efficient coordinated mining of the coal seam group is realized through optimization of working face arrangement and mining sequence of a system. A coal seam is divided into upper sections and lower sections, mining roadways are arranged in order, and a specific mining sequence is adopted, namely the first coal seam upper section is firstly mined, then the third coal seam upper section is mined, then the first coal seam lower section, the second coal seam upper section and the third coal seam lower section are sequentially mined, and finally the second coal seam lower section is mined. The length of the working face or the height of the section is adjusted according to the coal seam distance, mutual interference in the mining process is effectively reduced, operation safety is improved, meanwhile, roadway arrangement is optimized, the roadway surrounding rock stress environment is improved, the mining cost is reduced, and the mining efficiency is improved. And an innovative solution is provided for solving the technical problems in steeply inclined coal seam group mining.

Description

Technical Field

[0001] The present application relates to the field of mine mining technology, and in particular to a coordinated mining method for a deep, high-stress, steeply inclined coal seam group. Background Art

[0002] In my country's coal resource reserves, steeply inclined coal seams with a dip angle of more than 45° account for a significant proportion, accounting for about 15% to 20% of my country's total coal reserves. Such coal seams are rich in coking coal, anthracite and some rare coal species, and these resources are of vital strategic significance for promoting my country's industrial development and regional economic growth. However, as the resources of shallow coal seams that are easy to mine are gradually exhausted, the mining industry has begun to focus on steeply inclined coal seams with more complex geological conditions and greater technical mining difficulties. Therefore, exploring how to achieve efficient and safe mining technology for such coal seams has a far-reaching impact on improving the efficiency of my country's coal resource utilization, ensuring national energy security, and leading technological innovation and long-term development in the coal mining industry.

[0003] However, the mining technology of steeply inclined coal seams faces a series of scientific challenges. Especially in deep and high-stress environments, the mining of coal seams in close proximity will lead to complex interactions among multiple factors such as the mining face, roof movement, roof collapse, and gangue movement. This interaction not only increases the complexity of the mining process, but also significantly increases safety risks. Traditional mining technology often appears inefficient and has frequent safety hazards when dealing with these scientific problems.

[0004] In addition, when the coal seam is buried more than 300 meters deep, the deformation problem of soft coal tunnels becomes particularly serious, maintenance work becomes extremely difficult, and the stability and durability of the support structure are seriously affected. This not only increases the economic cost of mining, but also poses a potential threat to the life safety of operators.

[0005] In view of this, it is urgent to develop a new type of mining technology for the mining conditions of deep, high-stress, steeply inclined coal seams. This technology needs to be able to effectively coordinate the various complex factors in the mining of coal seams, aiming to improve mining efficiency while ensuring operational safety, thereby promoting technological progress and sustainable development of my country's coal mining industry. Summary of the invention

[0006] The embodiment of the present application provides a coordinated mining method for a group of deep, high-stress, steeply inclined coal seams, which can effectively coordinate the mining activities of each coal seam, reduce mutual influence during the mining process, improve mining efficiency, and ensure the safety of operations.

[0007] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0008] In a first aspect, an embodiment of the present invention provides a coordinated mining method for a deep, high-stress, steeply inclined coal seam group, which is applied to a steeply inclined coal seam group, wherein the steeply inclined coal seam group includes a first coal seam, a first composite rock layer, a second coal seam, a second composite rock layer, and a third coal seam sandwiched between an immediate roof and a floor, wherein the three coal seams are all thick coal seams with an inclination angle greater than 45°, and the method includes: dividing the first coal seam, the second coal seam, and the third coal seam into upper and lower sections, arranging mining lanes at both ends of the sections, the mining lanes are all arranged along the direction of the coal seams, and the section transport lanes of each section are connected to the section return air lanes through a working face;

[0009] According to the coal seam occurrence, firstly mine the upper section of the first coal seam, then mine the upper section of the third coal seam, and then mine the lower section of the first coal seam;

[0010] At the end of mining the lower section of the first coal seam, two lanes of the upper section of the second coal seam are excavated and maintained, and after mining of the two working faces of the first coal seam is completed, the upper section of the second coal seam is mined;

[0011] After mining the upper section working face of the second coal seam, the lower section working face of the third coal seam is mined, and finally the lower section working face of the second coal seam is mined.

[0012] In some possible implementations, when the distance between the second coal seam and the third coal seam is relatively large, the length of the working face or the height of the section is increased according to the roof movement law of steeply inclined coal seam mining, in which the range of roof damage during mining of the lower coal seam will not affect the mining range of the upper coal seam; increasing the length of the working face or the height of the section needs to meet the following principles:

[0013] H1·sin(90-α)≥d2;

[0014] Among them, H1 is the height of the upper section of the first coal seam, d2 is the distance between the second coal seam and the third coal seam, and α is the inclination angle of the coal seam;

[0015] When the distance between the second coal seam and the third coal seam is small, the section height is adjusted according to the above calculation principle, and the length of the longwall working face is made greater than a preset threshold to ensure mining efficiency.

[0016] In some possible implementations, during the tunnel layout process, a combination of flexible support and rigid support is used to ensure the long-term stability of the tunnel and avoid stress concentration areas in the goaf.

[0017] In some possible implementations, during the mining process, tunnel surrounding rock stress sensors and displacement monitoring devices are arranged to continuously monitor the tunnel top pressure, displacement and surrounding rock deformation, so as to grasp the stress distribution of the tunnel surrounding rock and the movement law of the roof in real time.

[0018] In some possible implementations, during the tunnel excavation process, a combination of bolt support and cable support is used to form a multiple support system, and the length and spacing of the cable anchors are adjusted according to the strength and stress distribution of the tunnel surrounding rock.

[0019] In some possible implementations, during the mining process, the support system is flexibly adjusted according to the mine pressure monitoring results to ensure the safety of the mining operation.

[0020] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] In the embodiment of the present invention, the efficient and coordinated mining of coal seam groups is achieved through the optimization of the working face arrangement and mining sequence of the system. The coal seam is divided into upper and lower sections, and the mining tunnels are arranged in an orderly manner. A specific mining sequence is adopted, that is, the upper section of the first coal seam is mined first, followed by the upper section of the third coal seam, and then the lower section of the first coal seam, the upper section of the second coal seam, the lower section of the third coal seam, and finally the lower section of the second coal seam. The working face length or section height is adjusted according to the coal seam spacing, which effectively reduces mutual interference in the mining process and improves the safety of the operation. At the same time, the tunnel layout is optimized, the stress environment of the surrounding rock of the tunnel is improved, the mining cost is reduced, and the mining efficiency is improved, which provides an innovative solution to the technical problems in the mining of steeply inclined coal seam groups. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0023] Figure 1 A schematic flow chart of an embodiment of a coordinated mining method for deep, high-stress, steeply inclined coal seams provided for the implementation of the present invention;

[0024] Figure 2 It is a structural schematic diagram of a steeply inclined coal seam group in an embodiment of the present invention;

[0025] Figure 3 This is a numerical simulation model diagram of an actual engineering example;

[0026] Figure 4a This is the distribution cloud diagram of the inclined stress during mining in Scheme 1;

[0027] Figure 4b This is the stress distribution cloud diagram during mining in Scheme 1;

[0028] Figure 5aThis is the distribution cloud diagram of the inclined stress during mining in Scheme 2;

[0029] Figure 5b This is the stress distribution cloud map during mining in Plan 2. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In the relevant description of this embodiment, the terms "including, containing, having" and the like are open terms and are generally understood to include but not be limited to; the term "at least one" is generally understood to mean one or more, where "plurality" refers to two or more; the term "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items, for example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively; the symbol "A / B" is used to describe the selection relationship of associated objects, generally indicating an "or" relationship before and after.

[0032] In the following description of the present embodiment, the terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0033] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0034] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as also specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0035] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to these may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0037] Figure 1 A schematic flow chart of an embodiment of a coordinated mining method for a deep, high-stress, steeply inclined coal seam group provided for the implementation of the present invention. The method can be applied to a steeply inclined coal seam group. The steeply inclined coal seam group may include a first coal seam, a first composite rock layer, a second coal seam, a second composite rock layer, and a third coal seam sandwiched between the immediate roof and the floor. The three coal seams are all thick coal seams with an inclination angle greater than 45°. Figure 1 As shown, the above method may include:

[0038] S101, the first coal seam, the second coal seam and the third coal seam are divided into two sections, an upper section and a lower section, and mining tunnels are arranged at both ends of the sections. The mining tunnels are arranged along the direction of the coal seams, and the section transport tunnel of each section is connected with the section return air tunnel through the working face;

[0039] For example, Figure 2 FIG. 1 is a schematic diagram of the structure of a steeply inclined coal seam group in an embodiment of the present invention, see Figure 2 As shown, the rock layers are arranged from top to bottom as follows: basic roof 3, direct roof 4, first coal seam 5, first composite rock layer 6, second coal seam 7, second composite rock layer 8, third coal seam 9 and floor 10. In addition, it also includes an upper section working face return air level tunnel 11 and a lower section working face transport level tunnel 12.

[0040] Among them, these three coal seams are all thick coal seams with an inclination greater than 45°. Therefore, their mining difficulty and technical requirements are relatively high.

[0041] In some embodiments, based on the geological survey results, the occurrence conditions of the first coal seam, the second coal seam, and the third coal seam can be first determined, including parameters such as the inclination angle, thickness, burial depth, roof and floor properties, and coal seam spacing. To ensure the stability and efficiency of mining operations, each coal layer can be divided into two sections, namely, an upper section and a lower section (e.g., Figure 2 The specific segment division not only considers the geological conditions of the coal seam, but also can be combined with the characteristics of the mine pressure distribution, stress concentration areas and the stability of the roadway in actual mining.

[0042] In some embodiments, in the section layout, the mining tunnels are arranged along the direction of the coal seam, that is, the transport tunnels and return air tunnels of the working face are arranged at both ends of the working face, respectively, to form a mining operation system. The section transport tunnel of each section is connected to the section return air tunnel through the working face to ensure the smooth operation of the ventilation system and the transportation system. In the process of tunnel layout, it is also necessary to reasonably design the support scheme according to the properties of the surrounding rock and the distribution of mine pressure. Due to the stress concentration of deep coal seams, the tunnels are prone to large deformation, so the support system must be strong enough. In the process of tunnel layout, a combination of flexible support and rigid support can be adopted.

[0043] In addition, in the process of roadway layout, special attention should be paid to the relative position of the roadways and the mutual influence between coal seams. Due to the particularity of steeply inclined coal seams, the layout of roadways cannot rely solely on conventional methods, but needs to be combined with the geometric form of coal seams and the law of stress transfer. In order to reduce the mutual interference between coal seams, the stress concentration area of ​​the goaf should be avoided as much as possible during the layout of the roadways to ensure the stability and safety of the roadways during the mining process.

[0044] S102, according to the occurrence of coal seams, first exploit the upper section of the first coal seam, then exploit the upper section of the third coal seam, and then exploit the lower section of the first coal seam;

[0045] S103, in the later stage of mining the lower section working face of the first coal seam, two lanes of the upper section working face of the second coal seam are excavated and maintained, and after the mining of the two working faces of the first coal seam is completed, the upper section working face of the second coal seam is mined;

[0046] S104, after mining the upper section working face of the second coal seam, mine the lower section working face of the third coal seam, and finally mine the lower section working face of the second coal seam.

[0047] It should be noted that, according to the occurrence conditions and engineering requirements of different coal seams, the present invention proposes a phased and layered mining sequence to effectively reduce the impact of roof damage on adjacent coal seams, and reasonably coordinate the mining activities of each layer of coal to ensure safe and efficient mining. The design of this mining sequence takes into account the complexity of the deep high-stress environment, especially the disturbance effect of mining on the surrounding tunnels and coal seams, and adopts a series of optimization measures.

[0048] For details, see Figure 2 As shown, the upper section working face (1# working face) of the first coal seam 5 is mined first. During the mining process of the 1# working face, tunnel surrounding rock stress sensors can be arranged to focus on monitoring the stress changes of the tunnel surrounding rock. Through real-time monitoring, the support plan should be adjusted in time to ensure the stability of the tunnel. If it is found that the tunnel surrounding rock has a tendency to be damaged, the support should be strengthened in time, and the supporting capacity of the surrounding rock should be improved by means such as grouting reinforcement.

[0049] Then, after completing the mining of the upper section of the first coal seam 5, continue to mine the upper section working face (3# working face) of the third coal seam 9. At this time, since the 1# working face has been mined, the stress of the original goaf is redistributed, so special attention needs to be paid to the support design of the upper section roadway of the third coal seam 9. Since the coal seam is in a high-stress environment and support is difficult, the use of a flexible support system (such as anchor rods, anchor cables and shotcrete technology) can effectively improve the support effect. In addition, since the upper section of the third coal seam 9 is relatively far away, the mining of the first coal seam 5 will not cause obvious disturbance to the roadway of the third coal seam 9, avoiding the support pressure caused by premature mining of the lower section coal seam.

[0050] After that, after the upper section of the third coal seam 9 is mined, the lower section working face (4# working face) of the first coal seam 5 is mined. At this time, while the lower section of the first coal seam 5 is mined, it is necessary to advance the tunnel of the upper section of the second coal seam 7. When digging the tunnel of the upper section of the second coal seam 7, attention must be paid to the influence of the stress of the goaf of the first coal seam 5 on the stability of the tunnel, and the support scheme must be adjusted appropriately to ensure the stability of the tunnel.

[0051] After the lower section working face of the first coal seam 5 is completed, the upper section working face (2# working face) of the second coal seam 7 is mined. Since the first coal seam 5 has been mined and a goaf has been formed, it has a greater impact on the pressure of the roof of the second coal seam 7. Therefore, when mining the second coal seam 7, it is necessary to monitor the changes in the surrounding rock stress of the tunnel in real time, and dynamically adjust the support plan based on the monitoring results to ensure the stability of the roof.

[0052] After the mining of the upper section of the second coal seam 7 is completed, the mining of the lower section of the third coal seam 9 (working face 6) is started. At this time, the mining of the lower section of the third coal seam 9 needs to lag behind the excavation of the lower section of the second coal seam 7 to avoid excessive disturbance of the upper goaf to the lower tunnel. By reasonably adjusting the mining sequence and reducing the interference between coal seams, the safety of the tunnel is guaranteed.

[0053] Finally, after the mining of the lower section of the third coal seam 9 is completed, the mining of the lower section working face (5# working face) of the second coal seam 7 begins. At this time, since the impact of the goaf of the upper coal seam has been effectively controlled, the mining disturbance of the lower section is small and the support difficulty is relatively low.

[0054] In some embodiments, since support is difficult in a high-stress environment, a reasonable mining sequence can minimize disturbances between coal seams. By first mining the upper section working face and then mining the lower section working face, the impact of mining the lower section on the upper section roadway that has been mined is effectively avoided, and the instability of the roadway surrounding rock is reduced. The mining sequence of different coal seams can adjust the support scheme according to the actual situation of each working face. For example, when mining the first coal seam 5 and the third coal seam 9, the mining sequence arrangement avoids excessive mining interference and contributes to the stability of the support system. Especially in high-stress sections, the use of flexible support technology effectively improves the stability of the roadway. By avoiding excessive interference between the upper and lower sections of the same coal seam, the concentration of roof pressure is reduced, and the risk of roof damage is reduced. The mining of each coal seam is appropriately adjusted according to the stress distribution to ensure the stability of the roof, and the support scheme is adjusted in real time through the monitoring of the surrounding rock of the roadway to avoid the occurrence of safety accidents such as roof collapse. This mining sequence not only ensures the safety of mining, but also improves the overall mining efficiency. By rationally arranging the mining sequence and support design between coal seams, unnecessary interference and risks are minimized, resource utilization is improved, and mine operating costs are reduced.

[0055] In some embodiments, the present invention focuses on the monitoring of tunnel pressure and surrounding rock deformation in the mining process of steeply inclined coal seams under deep high-stress conditions. In a high-stress environment, the mining of steeply inclined coal seams may cause roof instability, which in turn affects the safety of the entire mining process. Therefore, timely grasping the stress changes and deformation of the tunnel surrounding rock, especially the stability of the roof, is the key to ensuring safe mining. In the actual mining process, the activity pattern of the coal seam roof is relatively complex. The collapse of the roof will not only affect the stability of the current coal seam, but may also have a secondary impact on the mining of adjacent coal seams. Therefore, the use of advanced mine pressure monitoring technology to monitor the roof in real time is an important measure in the scheme of the present invention. In order to ensure the stability of the tunnel during the mining process, the present invention also proposes the following monitoring measures:

[0056] (1) Arrangement of pressure and displacement monitoring equipment: Stress sensors and displacement monitoring devices are arranged above each working surface. Through continuous monitoring of the pressure, displacement and deformation of the surrounding rock at the top of the tunnel, the stress distribution of the tunnel surrounding rock and the movement law of the roof can be grasped in real time. When the stress sensor detects abnormal changes, especially in areas of stress concentration, the system will issue an early warning in time to indicate possible safety hazards.

[0057] (2) Analysis of stress and deformation monitoring data: The monitoring data will be transmitted to the mine monitoring center in real time, and after professional analysis, the stability of the surrounding rock will be evaluated. If the monitoring results show that the roof is at risk of damage or collapse, timely measures will be taken, such as strengthening support, adjusting support plans, or using local grouting reinforcement to control the deformation of the tunnel and reduce the occurrence of accidents.

[0058] (3) Support and reinforcement measures: By analyzing the monitoring data, the deformation degree of the tunnel surrounding rock and the trend of roof activity can be determined. When potential damage trends are found, remedial measures such as grouting reinforcement, tunnel advance support, and isolation coal pillars can be implemented.

[0059] During the mining process, the force changes of the coal body can be simplified by the moment expression. The calculation formula can be expressed as:

[0060]

[0061] Among them, M is the moment, the unit is N·m; G is the force on the coal body, which can generally be calculated at the neutral position of each layer, the unit is N; L 纵 is the length of the longitudinal slope, in meters; α is the inclination of the coal seam. This moment calculation formula is used to evaluate the stress of the coal body during mining, help analyze the relationship between roof activity and moment, and thus provide theoretical support for tunnel support and reinforcement.

[0062] In some embodiments, during tunneling, the stability of the tunnel is particularly critical due to the special geometry of the steeply inclined coal seam. Stress concentration and surrounding rock deformation in deep coal seams are the main factors leading to tunnel instability. Therefore, the present invention needs to focus on the optimization design of tunneling and support systems.

[0063] When excavating a tunnel, a combination of bolt support and cable support can be used to form a multiple support system. In specific operations, bolts are first installed on the tunnel wall to form a primary support system with the surrounding rock. Cables are then arranged to further strengthen the support of the tunnel roof and side walls. The selection of anchor cables should be based on the strength and stress distribution of the tunnel surrounding rock, and the length and spacing of the anchor cables should be adjusted to ensure the stability of the support system.

[0064] In addition, when the spacing between coal seams is small, the difficulty of supporting the tunnel excavation increases. For this reason, it is recommended to use advanced support technology to prepare support in advance before tunnel excavation to reduce the deformation of the tunnel surrounding rock. After the tunnel excavation is completed, the surrounding rock surface can be further reinforced in combination with shotcrete technology to improve the overall stability of the tunnel.

[0065] In some embodiments, when mining steeply inclined coal seams, changes in mine pressure are an important factor affecting mining safety and efficiency. The present invention also proposes a dynamic support adjustment scheme, which flexibly adjusts the support system according to the mine pressure monitoring results.

[0066] For example, when the coal seam is buried more than 300 meters deep, the risk of roof collapse in the goaf increases due to concentrated ground pressure, and traditional support methods may not be sufficient to cope with complex changes in mine pressure. In this case, the safety of mining operations can be ensured by increasing support strength and extending support range.

[0067] When the distance between coal seams is small, the present invention also proposes a suggestion for appropriate adjustment of the section height H1 or H2. By reducing the section height, the damage range of the roof during mining can be reduced and the risk of stress concentration areas can be reduced. It should be noted that we have made appropriate adjustments to the working face length (L) or section height (H1 or H2) based on the law of roof movement during the mining of steeply inclined coal seams, that is, the damage range of the roof during the mining of the lower coal layer will not affect the mining range of the upper coal layer. This adjustment follows strict mathematical calculation principles by appropriately increasing the working face length (L) or section height (H1 or H2) to ensure the safety and efficiency of the mining process. The mathematical calculation principle can be expressed as:

[0068] H1·sin(90-α)≥d2;

[0069] That is, H1·sinβ≥d2.

[0070] Among them, H1 is the upper section height of the first coal seam, d2 is the distance between the second coal seam and the third coal seam, α is the inclination angle of the coal seam, and β is the complementary angle of the inclination angle of the coal seam.

[0071] The application of the above formula enables the optimal section height and working face length to be accurately calculated based on specific coal seam conditions and mining requirements.

[0072] It should be noted that when the distance (d2) between the second coal seam 7 and the third coal seam 9 is small, the section height (H1 or H2) can be appropriately adjusted according to the above calculation basis. Among them, the length of the longwall working face needs to be greater than a preset threshold. The size of the preset threshold can be an empirical value, or it can be determined based on the needs in actual applications. For example, the length of the longwall working face can be greater than 80 meters to ensure the mining efficiency and output of the coal seam. In the case of insufficient working face length, the roof may collapse prematurely, thereby affecting the mining of the entire coal seam group.

[0073] In some embodiments, during coal seam mining, gangue treatment is an important link to ensure the smooth progress of mining operations. Due to the geological characteristics of steeply inclined coal seams, the movement and accumulation of gangue may pose a threat to the tunnel. Therefore, the present invention also proposes a gangue control scheme, which reduces the impact of gangue on the tunnel by arranging a gangue retaining wall in the tunnel. In addition, during tunnel excavation, combined with the physical properties of coal and rock, a reasonable gangue cleaning and transportation scheme is designed to ensure the smooth flow of the tunnel.

[0074] During the entire mining process, tunnel maintenance is also crucial. Due to the large stress changes in steeply inclined coal seams, tunnel deformation is prone to occur, so tunnels need to be inspected regularly and support adjustments or re-reinforced according to the deformation conditions. Tunnel maintenance work should be based on the mechanical properties of the tunnel surrounding rock and adopt flexible support measures, such as adding anchors, shotcrete reinforcement, etc., to ensure the long-term stability of the tunnel during the mining process.

[0075] In some embodiments, in order to better understand the advantages of the scheme of the present invention, numerical simulation calculations and analysis of stress cloud maps in the embodiments of the present invention can more intuitively and accurately reflect the advantages of the scheme of the present invention and provide more powerful support for it.

[0076] Exemplarily, the embodiment of the present invention adopts FLAC 3D The software performs numerical simulation calculations, and the simulation process is carried out in the following steps: Based on the actual geological conditions, a three-dimensional numerical simulation calculation model is established - according to the mechanical properties of the coal seam and surrounding rock, a suitable constitutive model is selected, and reasonable mechanical parameters are assigned to various materials in the model - through the analysis of the geological conditions of the mining area, reasonable boundary conditions and initial stress states are set - multiple measuring points are arranged in the simulation model to monitor the stress changes at different positions during the mining process - through the gradual mining and solution of the model, the changes in the stress field during the mining process of the working face are simulated - the changing laws of the stress distribution of the working face under different mining schemes are compared, especially the differences in the stress concentration areas of each scheme during the mining process.

[0077] Taking a typical deep high-stress steeply inclined coal seam group as an example, the mining scheme of the present invention and the conventional mining scheme are compared and analyzed by numerical simulation method. -1 (upper part), 15 -34 There are three steeply inclined coal seams, 18 (middle) and 18 (lower), with an average inclination of 45° and an average burial depth of 375m. The spacing between the three coal seams is 30m, which is consistent with the situation described in the present invention. Figure 3 This is a numerical simulation model diagram of an actual engineering example. Figure 3 As shown in the figure, the three coal layers are divided into two sections, upper and lower, and 15 -1 Coal seam upper section working face, 15 -34Coal seam upper section working face, 18 coal seam upper section working face, 15 -1 Coal seam lower section working face, 15 -34 The working faces of the lower section of the coal seam and the lower section of the 18th coal seam are named 1# working face to 6# working face. The mine adopts the pseudo-inclined longwall mining method, with a pseudo-inclined angle of 8°, a working face length of 135m, and a thrust length of 200m. According to the actual geological conditions of the target coal mine, a 430×320×320m numerical calculation model was established. Two mining schemes were determined according to different mining sequences and the stress distribution of the working face during the mining process of each scheme was compared, and finally the optimal scheme was determined.

[0078] Among them, the upward or downward sequential mining may have an impact on each adjacent layer, and the stage vertical height h. When the upper layer is mined first, when the coal seam inclination angle α is greater than the bottom rock layer movement angle γ, and the interlayer spacing is less than M, the lower coal HSBC lane may be damaged; when the lower layer is mined first, when the coal seam inclination angle α is greater than the top rock layer movement angle β, and the interlayer spacing is less than M, the upper coal return air lane may be damaged.

[0079] Therefore, the conditions that should be met for descending sequential mining can be expressed as:

[0080]

[0081] The conditions that should be met for upward sequential mining can be expressed as:

[0082]

[0083] Specifically, by comparing the scheme of the present invention with the conventional mining scheme, the following two mining sequences are determined as mining schemes:

[0084] Plan 1: 1# working face → 4# working face → 2# working face → 5# working face → 3# working face → 6# working face (first mining 15 -1 Coal, then 15 -34 Coal, finally mining 18 coal, that is, mining in sequence from top to bottom);

[0085] Solution 2: 1# working face → 3# working face → 4# working face → 2# working face → 6# working face → 5# working face (mining sequence adopted in the embodiment of the present invention).

[0086] See also Figure 4a to Figure 4b , Figure 5a to Figure 5b As shown, Figure 4a This is the stress distribution cloud diagram of the first mining scheme. Figure 4b This is the stress distribution cloud diagram during mining in Scheme 1. Figure 5a This is the distribution cloud diagram of the inclined stress during mining in Scheme 2. Figure 5bThis is the stress distribution cloud diagram of the second mining scheme. The numerical simulation results are based on the stress distribution when the last working face is mined, and the two schemes are compared. Specifically, they include:

[0087] (1) Comparison of stress distribution: In terms of the distribution of dip stress, the stress cloud diagrams of the two schemes are basically similar, but the differences are still significant. When mining the 6# working face in Scheme 1, there is a large concentrated area of ​​dip stress distribution, especially in the upper area of ​​the working face, showing a higher stress value. In comparison, when mining the 5# working face in Scheme 2, although the magnitude of dip stress is similar to that of Scheme 1, and the stress value in the upper inclined part of the working face is higher, the distribution of its strike stress is more uniform, the concentrated area is smaller, and the overall stress influence range is smaller.

[0088] (2) Comparison of stress concentration areas: By comparing the stress concentration levels of the two schemes, it is found that the stress concentration area of ​​Scheme 2 is significantly smaller, which means that the stability of the surrounding rock is relatively better. In Scheme 2, the stress influence range is smaller, the impact on the surrounding coal seams and surrounding rocks is relatively limited, and the ground pressure activity generated during mining is smaller, which has better safety than Scheme 1.

[0089] (3) Mining safety analysis: In the mining process of Scheme 2, the stress distribution of the working face is more uniform, and the overall stress concentration area is relatively small, which has a positive effect on the safety of coal mining. The numerical simulation results show that the stress field of Scheme 2 changes more smoothly, the surrounding rock is more stable, and the ground pressure activity during the mining process is smaller, thereby reducing safety risks such as water inrush, wind inrush, and roof collapse.

[0090] based on Figure 4a to Figure 4b , Figure 5a to Figure 5b Comparing the stress concentration of the two schemes, it can be found that the stress concentration area of ​​Scheme 2 is relatively smaller, and the surrounding rock stability is relatively better; the stress influence range of Scheme 2 is smaller, and the impact on the surrounding coal seams and surrounding rocks is relatively small; at the same time, the stress distribution of Scheme 2 is more uniform, and the ground pressure activity may be smaller during the mining process, which is relatively safer. The numerical simulation calculation results show that the scheme of the present invention has significant advantages over conventional mining schemes. The stress distribution of Scheme 2 is more uniform, the surrounding rock stability is better, and the impact on the surrounding coal seams and surrounding rocks is smaller, thereby improving the safety and economy of mining.

[0091] In summary, the coordinated mining method for deep high-stress steeply inclined coal seams proposed by the present invention can effectively reduce the stress concentration area, reduce the risk of ground pressure activity, and improve the safety level of mine production compared with conventional mining schemes. Therefore, the present invention has important application value and promotion significance in the mining of deep high-stress steeply inclined coal seams.

[0092] In the embodiment of the present invention, the efficient and coordinated mining of coal seam groups is achieved through the optimization of the working face arrangement and mining sequence of the system. The coal seam is divided into upper and lower sections, and the mining tunnels are arranged in an orderly manner. A specific mining sequence is adopted, that is, the upper section of the first coal seam is mined first, followed by the upper section of the third coal seam, and then the lower section of the first coal seam, the upper section of the second coal seam, the lower section of the third coal seam, and finally the lower section of the second coal seam. The working face length or section height is adjusted according to the coal seam spacing, which effectively reduces mutual interference in the mining process and improves the safety of the operation. At the same time, the tunnel layout is optimized, the stress environment of the surrounding rock of the tunnel is improved, the mining cost is reduced, and the mining efficiency is improved, which provides an innovative solution to the technical problems in the mining of steeply inclined coal seam groups.

[0093] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0094] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A coordinated mining method for deep high-stress steeply inclined coal seams, characterized in that: The method is applied to a group of steeply inclined coal seams, which includes a first coal seam, a first composite rock layer, a second coal seam, a second composite rock layer, and a third coal seam sandwiched between an immediate roof and a floor, and all three coal seams are thick coal seams with an inclination angle greater than 45°. The method includes: The first coal seam, the second coal seam and the third coal seam are divided into two sections, an upper section and a lower section, and mining lanes are arranged at both ends of the sections. The mining lanes are arranged along the direction of the coal seams, and the section transport lane of each section is connected with the section return air lane through the working face; According to the coal seam occurrence, firstly mine the upper section of the first coal seam, then mine the upper section of the third coal seam, and then mine the lower section of the first coal seam; At the end of mining the lower section of the first coal seam, two lanes of the upper section of the second coal seam are excavated and maintained, and after mining of the two working faces of the first coal seam is completed, the upper section of the second coal seam is mined; After mining the upper section working face of the second coal seam, the lower section working face of the third coal seam is mined, and finally the lower section working face of the second coal seam is mined.

2. The method according to claim 1, characterized in that When the distance between the second coal seam and the third coal seam is large, the length of the working face or the height of the section is increased according to the roof movement law of steeply inclined coal seam mining, in which the range of roof damage during mining of the lower coal seam will not affect the mining range of the upper coal seam; wherein the calculation principles that need to be met for increasing the length of the working face or the height of the section include: H1·sin(90-α)≥d2; Among them, H1 is the height of the upper section of the first coal seam, d2 is the distance between the second coal seam and the third coal seam, and α is the inclination angle of the coal seam; When the distance between the second coal seam and the third coal seam is small, the section height is adjusted according to the calculation principle, and the length of the longwall working face is made greater than a preset threshold to ensure mining efficiency.

3. The method according to claim 2, characterized in that During the tunnel layout process, a combination of flexible support and rigid support is adopted to ensure the long-term stability of the tunnel and avoid stress concentration areas in the goaf.

4. The method according to claim 3, characterized in that During the mining process, tunnel surrounding rock stress sensors and displacement monitoring devices are arranged to continuously monitor the tunnel top pressure, displacement and surrounding rock deformation, so as to grasp the stress distribution of the tunnel surrounding rock and the movement law of the roof in real time.

5. The method according to claim 4, characterized in that During the tunnel excavation process, a combination of anchor support and anchor cable support is adopted to form a multiple support system, and the length and spacing of the anchor cables are adjusted according to the strength and stress distribution of the tunnel surrounding rock.

6. The method according to claim 5, characterized in that During the mining process, the support system is flexibly adjusted according to the mine pressure monitoring results to ensure the safety of mining operations.

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