Double-pseudo-inclined continuous mining and continuous filling mining method for steeply inclined short-distance coal seam group

Abstract

The invention discloses a double-pseudo-inclined continuous mining and continuous filling mining method for a steeply inclined close-distance coal seam group, which comprises the following steps of: selecting a proper working face mining roadway system according to the condition of a coal seam; the transportation roadway, the air return roadway and the stope face are all arranged in a pseudo-inclined mode; a boundary air guide way is arranged between the transportation way and the air return way in an inclination adjusting mode; according to the gradeability of the equipment, the false dip angle eta of the transportation roadway and the return airway and the false dip angle gamma of the working face are determined; determining the width of the interval coal pillars; the working face is divided into a plurality of branch roadways according to a certain width in the direction parallel to the boundary air guide roadway; and coal mining is carried out on the working face in a continuous mining and continuous filling mode. According to the mining method, the working face air return way, the transportation way and the boundary air guide way are arranged in a pseudo-inclined mode, and a full-negative-pressure ventilation system is formed. By optimizing the roadway included angle, mining and filling parallel operation is achieved, equipment moving and secondary operation are reduced, and the tunneling efficiency and the coal productivity are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mining, and relates to a steeply inclined coal seam mining method, and in particular to a double pseudo-inclined continuous mining and filling mining method for a steeply inclined close-range coal seam group. Background Art

[0002] Steeply inclined coal seams, defined as those with an inclination greater than 45°, account for 10-20% of China's total coal reserves. Due to the effects of gravity and the complex coal-forming environment, their mining is challenging, resulting in low safety and productivity benefits. They are recognized as difficult-to-mine coal seams by the mining community both domestically and internationally. Mining of steeply inclined coal seams in my country began in the 1950s, primarily using non-mechanized methods such as silo mining, reverse bench mining, horizontal layered mining, horizontal layered top coal caving, and single-stage full-height layered mining. After the 1970s, mines in the Huaibei and Huainan regions with better conditions began to experiment with conventional mechanized mining of steeply inclined coal seams, exemplified by the pseudo-inclined flexible shield mining method. These methods subsequently matured through widespread adoption. While flexible, simple, and highly targeted, these methods have yet to fully address the fundamental issues of low productivity and poor safety and efficiency in steeply inclined coal seams. From the late 1980s to the early 21st century, the strike longwall comprehensive mechanized mining method and the strike longwall comprehensive mechanized top coal caving mining method, which are suitable for steeply inclined medium-thick coal seams with an inclination of less than 60°, were proposed respectively; and the horizontal segmented comprehensive mechanized top coal caving mining method, which is suitable for coal thickness of more than 20m and an inclination of more than 60°, was proposed and quickly promoted, further improving coal production capacity and safety benefits.

[0003] Currently, comprehensive mechanized mining has been achieved in steeply inclined, thin, medium-thick, and extra-thick coal seams with inclinations below 60°, and is gradually evolving towards automated and intelligent mining. Since 2015, the Xi'an University of Science and Technology's safe and efficient mining theory and technology team for complex and difficult-to-mine coal seams has innovatively proposed a horizontally segmented coordinated mining method and a shortwall fully mechanized top-coal caving combined mining method for steeply inclined, close-packed, and extra-thick coal groups. They have conducted system layout, mining process design, and related experimental research, and have completed industrial trials. However, with increasingly stringent environmental standards and requirements for mining area development, as well as the implementation of relevant environmental laws such as the "Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Wastes," traditional waste rock disposal methods no longer meet the requirements for green and efficient mining in modern mines. Existing mining methods and technologies are unable to address the waste rock problem generated by mining. To further meet the country's urgent need for efficient development of scarce coal resources, innovative mining methods for steeply inclined, close-packed coal seams are urgently needed to achieve green, safe, and efficient mining of these seams.

[0004] As an important development direction of green mining, continuous mining and backfilling technology has achieved remarkable results in the mining of gently inclined coal seams in my country. This technology effectively controls surrounding rock deformation and surface subsidence through parallel mining and backfilling operations, significantly improving resource recovery rates. Currently, industrial applications are mainly concentrated in near-horizontal and gently inclined coal seams with an inclination of less than 35° (such as the Xingtai and Huaibei mining areas). Its core advantage lies in the rapid advancement of continuous coal miners, combined with highly fluid backfilling materials to achieve immediate support of the goaf, significantly improving the manifestation of mine pressure. However, this technology has not yet been applied in engineering in the field of steeply inclined coal seams, especially for close-range coal seam groups with inclinations of 55-75° and interlayer thicknesses of 5-8m. There are bottlenecks such as poor adaptability of equipment to large inclination angles, tunnel system layout, and mining and backfilling coordination obstacles. Traditional continuous mining and backfilling methods face severe challenges such as failure of surrounding rock control in the stope and insufficient recovery rates. Therefore, it is urgent to break through the existing technical framework and build a new green mining model that is suitable for steeply inclined and close-range coal seam groups. Summary of the Invention

[0005] In order to solve the shortcomings of the existing mining process in terms of poor adaptability of equipment to large inclination angles, tunnel system layout, and mining and filling coordination obstacles, the present invention aims to provide a double pseudo-inclination continuous mining and filling method for steeply inclined and close-range coal seam groups. By determining the pseudo-inclination, improving the layout of the working face mining tunnel system, and optimizing the mining and filling process flow, the purpose of safe, green and efficient mining of steeply inclined and close-range coal seam groups with a single coal seam thickness of 1.5 to 3.5 meters and an interval rock layer thickness of 5 to 8 meters can be achieved.

[0006] The present invention provides a double pseudo-inclined continuous mining and filling mining method for a group of steeply inclined and closely spaced coal seams, comprising the following steps:

[0007] According to the coal seam conditions, select a suitable continuous mining and continuous filling working face mining tunnel system;

[0008] The transport tunnel, return air tunnel, and mining working face are all arranged in a pseudo-inclined manner;

[0009] Determine the pseudo inclination angle η of the transport lane and the return air lane, and the pseudo inclination angle γ of the working surface according to the climbing ability of the equipment;

[0010] Determine the width of the interval coal pillars; divide the working face into a number of parallel branch lanes according to a certain width;

[0011] Coal mining at the working face is carried out using the continuous mining and filling method.

[0012] Furthermore, the transport tunnel and the return air tunnel are arranged in a downward pseudo-inclined manner, with the main body being downward mining; or they are arranged in an upward pseudo-inclined manner, with the main body being upward mining; downward mining is suitable for coal seams with complex hydrogeological conditions, groundwater threats, thin upper coal seam oxidation zones and low risk of filling paste sliding; upward mining is suitable for coal seams with low gas content and simple hydrogeological conditions, which require deep mining or have a tendency to rock burst.

[0013] Furthermore, a boundary air guide tunnel is arranged between the transport tunnel and the return air tunnel in parallel with the working face; and a protective coal pillar is left between the boundary air guide tunnel and the working face.

[0014] Furthermore, the pseudo inclination angle γ of the working surface is:

[0015] γ=arcsin(sinαcos(ω+θ))

[0016] Among them, γ is the pseudo-inclination angle of the working face, (°); α is the true inclination angle of the steeply inclined coal seam, (°); θ is the inclination adjustment angle of the first type of boundary air guide tunnel, (°); ω is the inclination adjustment angle of the second type of double pseudo-inclination mining working face, (°); (ω+θ) is the plane angle of the boundary air guide tunnel.

[0017] Furthermore, the working face forms full negative pressure ventilation of the entire working face with the transport tunnel and the return air tunnel; full negative pressure ventilation and local fans are used for ventilation during coal mining.

[0018] Furthermore, theoretical calculation is used to determine the reasonable range of interval coal pillar width, and numerical simulation is used to determine the optimal interval coal pillar width based on the stability of the surrounding rock.

[0019] Furthermore, according to the Obert-Duvall / Wang Formula coal pillar ultimate strength formula and safety factor comparison method, we can obtain:

[0020]

[0021] Where σ p is the ultimate strength of the coal pillar; P max is the maximum load on the top plate; σ c is the uniaxial compressive strength of the coal body; w is the width of the coal pillar; h is the height of the coal pillar; r is the bulk density of the overlying rock layer, KN / m 3 ; H is the depth of coal seam, m; is the internal friction angle of the coal seam; E is the elastic modulus of the coal seam; α is the inclination angle of the coal seam;

[0022] And according to the above formula, the reasonable range of the width w of the interval coal pillar is obtained.

[0023] Furthermore, according to the width of the interval coal pillars and the cross-sectional width of the excavation branch tunnels, several branch tunnels are divided into one group, with 3 groups as parallel mining and filling areas, and a skip mining method is adopted during the excavation and filling process.

[0024] The present invention is beneficial in that:

[0025] 1. The present invention provides a double pseudo-inclined continuous mining and filling method for a group of steeply inclined and close-range coal seams. The working face return air lane, transport lane, boundary air guide lane and mining and filling branch lane are all arranged in a pseudo-inclined manner, which reduces the angle of the mining and filling branch lanes and improves coal recovery efficiency and coal production capacity. Through parallel mining and filling operations, filling gangue replaces the coal seam, achieving safe and efficient mining and solid waste disposal, improving the recovery rate and taking into account both intensive resource utilization and environmental protection.

[0026] 2. The double pseudo-inclined continuous mining and filling mining method for steeply inclined and close-range coal seam groups provided by the present invention proposes two continuous mining and filling working face tunnel arrangements for different coal seam occurrence conditions: a double downward pseudo-inclined downward mining tunnel arrangement suitable for coal seams with complex hydrogeological conditions, groundwater threats, thin upper coal seam oxidation zones and low risk of filling paste sliding; and a double upward pseudo-inclined upward mining tunnel arrangement suitable for coal seams with low gas content, simple hydrogeological conditions, deep mining requirements or rock burst tendency.

[0027] 3. The dual-pseudo-inclined continuous mining and backfilling method for steeply inclined, closely spaced coal seams provided by this invention demonstrates excellent overall performance in terms of technology, economy, safety, and environmental protection. It provides a practical and feasible technical solution for efficient and green mining in mines and has excellent prospects for widespread application. While ensuring safe and efficient mining, this technology is expected to be applied to many steeply inclined coal seam mines, providing valuable experience and technical support for the development of steeply inclined coal seam mining and backfilling mining technologies in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] For a more complete understanding of the present invention, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 This is a schematic diagram of the layout of the tunnels in the double-down pseudo-inclined continuous mining and continuous filling downward mining working face of a group of steeply inclined and close-spaced coal seams according to the present invention;

[0030] Figure 2 This is a schematic diagram of the layout of the roadway in the double-upward pseudo-inclined continuous mining and continuous filling upward mining working face of a group of steeply inclined and close-spaced coal seams according to the present invention;

[0031] Figure 3 This is a comparison diagram of two types of boundary air guide tunnel layouts for double pseudo-inclined continuous mining and continuous filling mining of steeply inclined and close-spaced coal seams in the present invention;

[0032] Figure 4This is a schematic diagram of the arrangement of double pseudo-inclined continuous mining and filling working face tunnels in a coal seam for a group of steeply inclined and close-spaced coal seams according to the present invention;

[0033] Figure 5 This is a schematic diagram of the ventilation route for the double pseudo-inclined continuous mining and filling working face of a steeply inclined and close-range coal seam group according to the present invention.

[0034] Figure 6 This is a schematic diagram of the grouping of branch lanes in the double pseudo-inclined continuous mining and filling working face of a steeply inclined and close-distance coal seam group according to the present invention.

[0035] In the figure: 1. Transport tunnel; 2. Return air tunnel; 3. First-class boundary air guide tunnel; 4. Second-class boundary air guide tunnel; 5. Section transport stone gate; 6. Section return air stone gate; 7. Coal seam; 8. Floor; 9. Roof; 10. Filling branch tunnel; 11. Coal mining branch tunnel; 12. Fresh air flow; 13. Exhaust air flow; 14. Local ventilation; 15. Coal seam inclination; 16. Protective coal pillar. DETAILED DESCRIPTION

[0036] To clearly illustrate the purpose, technical details, and effective applications of the present invention and to facilitate understanding and implementation by those skilled in the art, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings. Obviously, the embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not intended to limit the present invention.

[0037] The present invention provides a double pseudo-inclined continuous mining and filling mining method for a group of steeply inclined and closely spaced coal seams, which is suitable for steeply inclined medium-thick coal seams with a coal seam inclination angle greater than 45°, a coal seam thickness of 1.5 to 3.5 meters, and an intervening rock layer thickness of less than 5 to 8 meters. The mining method specifically includes the following steps:

[0038] Step S01: Select a suitable working face mining tunnel system based on the conditions of the steeply inclined close-range coal seam; wherein the transport tunnel 1, the return air tunnel 2, and the mining working face are all arranged in a pseudo-inclined manner; and the boundary air guide tunnel 4 is arranged in an inclined manner between the transport tunnel 1 and the return air tunnel 2.

[0039] The pseudo-inclined arrangement means that there is an angle between the direction of the roadway or the direction of the working face and the direction of the coal seam.

[0040] According to the conditions of the steeply inclined coal seam, the working face mining tunnel system can be arranged in two ways, namely, the downward mining method and the upward mining method, such as Figure 1 、 Figure 2 shown.

[0041] Figure 1 The figure shows the downward mining method, that is, the transport tunnel 1 and the return air tunnel 2 are arranged in a downward pseudo-inclined manner, and the main mining method is downward mining; Figure 2 The figure shows the upward mining method, that is, the transport tunnel 1 and the return air tunnel 2 are arranged upward and obliquely, and the main body is upward mining.

[0042] use Figure 1 The engineering advantages of the downward mining method shown are: ① convenient drainage, allowing groundwater to be drained in advance after mining above, reducing the risk of water inrush during mining below; ② the mining sequence conforms to conventional processes (such as longwall face advancement), the technology is mature, and it is easy to manage; ③ the haulage lanes are inclined downward, making transportation easier. The engineering disadvantages are: ① the branch lanes are arranged along the uphill slope, and when excavating even-numbered branch lanes, there is a risk of vertical slippage of the filling paste in the odd-numbered filling lanes; ② the branch lanes are arranged along the uphill slope, with the upper part being a wind-oxidized coal seam, and the mineable coal seam reserves are limited.

[0043] use Figure 2 The engineering advantages of the upward mining method are: ① The risk of vertical slippage of the paste filling in the branch tunnel is reduced; ② Mining the lower coal seam first can preemptively release stress in the upper coal and rock layers, reducing the risk of ground pressure surges during upper mining. The engineering disadvantages are: ① The transport tunnel is inclined upward, making it prone to water accumulation; ② Insufficient gas release during mining can lead to gas-rich areas in the lower layers, increasing safety risks.

[0044] The specific method of adopting downward mining or upward mining can be based on the actual situation of the coal mine and a comprehensive comparative analysis can be conducted to select a better mining plan.

[0045] In order to clearly illustrate the method provided by the present invention, a coal mine with an annual output of 600,000 tons is taken as an example to introduce the specific application of the method provided by the present invention.

[0046] The mine operates 330 days a year, with 9 daily cycles. The shearer cuts 0.63m deep and the mining height is 3m. The upper coal seam is 2.69m thick, with an interval rock layer 7.11m thick. The coal seam has a dip of 54°, belonging to a group of steeply inclined, close-packed coal seams. The apparent density of the coal is 1.37g / cm 3 , the recovery rate is 75%.

[0047] For the coal mine described in this embodiment, based on the current development status of the coal mine and the occurrence characteristics of the upper coal seam within the mining area, combined with the requirements for the layout of the continuous mining and continuous filling working face system, in order to ensure the smooth application of the continuous mining and continuous filling technology in steeply inclined coal seams, taking into account the safety risks that may be caused when excavating branch tunnels in the downward mining method, the limited reserves of mineable coal seams in the uphill direction and other inevitable shortcomings, the upward mining method was selected through preliminary comparison, that is, the double-upward pseudo-inclined continuous mining and continuous filling upward mining tunnel system layout was adopted.

[0048] Specifically, the working face mining tunnel adopts a double-tunnel, double-upright pseudo-inclined layout, that is, the transport tunnel 1 and return air tunnel 2 are arranged upright pseudo-inclined along both sides of the working face; the transport tunnel 1 serves as the coal transportation channel and also serves as the working face air intake tunnel; the return air tunnel 2 serves as the main transportation channel for equipment and materials and also serves as the working face return air tunnel.

[0049] A boundary air guide tunnel 4 is arranged between the transport tunnel 1 and the return air tunnel 2 to pass through the transport tunnel 1 and the return air tunnel 2; a protective coal pillar 16 is left between the boundary air guide tunnel 4 and the mining working face.

[0050] According to the mining equipment and filling conditions, the working face is divided into several branch tunnels of a certain width in a direction parallel to the boundary air guide tunnel 4. Generally, two mining tunnels are arranged, and a belt is arranged on the side of the transport tunnel 1 near the coal seam.

[0051] Step S02: Determine the pseudo inclination angle η of the transport tunnel 1 and the return air tunnel 2, and the pseudo inclination angle γ of the working surface according to the climbing ability of the equipment.

[0052] Figure 3 Two arrangements of the boundary air guide tunnel 4 are shown, namely the first type of double-inclined mining: the boundary air guide tunnel 3 is arranged vertically with the transport tunnel 1 and the return air tunnel 2; and the second type of double-inclined mining: the boundary air guide tunnel 4 is arranged obliquely with the transport tunnel 1 and the return air tunnel 2.

[0053] In a continuous mining and continuous filling working face, the excavation branch tunnels are parallel to the 3 / 4 boundary ventilation tunnel. Therefore, compared with the first type of double-incline mining, the second type of double-incline mining with the boundary ventilation tunnel can significantly reduce the tunnel inclination angle, making it more convenient for tunneling equipment to operate in steeply inclined coal seams. Therefore, the present invention prefers the second type of double-incline mining with the boundary ventilation tunnel arrangement.

[0054] First, the pseudo-inclination angle η of the transport tunnel 1 and the return air tunnel 2 is selected based on the climbing ability of equipment such as fully mechanized excavation equipment and continuous coal mining machines.

[0055] Specifically in this embodiment, considering that the maximum climbing ability of the comprehensive excavation equipment is generally 16° and the maximum climbing ability of the continuous coal mining machine is generally 18°, in order to ensure the smooth construction of the excavation equipment in the continuous mining and filling working face of the steeply inclined coal seam, it is preliminarily determined that the pseudo-inclination angle η of the continuous mining and filling working face transport tunnel 1 and return air tunnel 2 is 15°.

[0056] Secondly, the pseudo-inclination angle γ of the boundary air guide tunnel 4 is determined based on the equipment's climbing ability.

[0057] refer to Figure 3 According to the geometric relationship, the pseudo-inclination angle γ of the boundary air guide tunnel 4 can be determined as:

[0058] γ=arcsin(sinαcos(ω+θ))

[0059] Among them, γ is the pseudo-inclination angle of the boundary air guide tunnel 4, which is also the pseudo-inclination angle of the double-inclination mining working face, (°); α is the true inclination angle of the steeply inclined coal seam, (°); θ is the adjustment angle of the first type of boundary air guide tunnel, (°); ω is the adjustment angle of the second type of double-inclination mining working face, (°); (ω+θ) is the plane angle of the boundary air guide tunnel.

[0060] Specifically in this embodiment, combined with the average inclination angle of the upper coal seam of the mine (α=54°), different surface angles (ω+θ) of the boundary air guide tunnel 4 are set. After inverse calculation, the pseudo inclination angle γ of the boundary air guide tunnel 4 under different surface angles is obtained as shown in Table 1.

[0061] Table 1 Pseudo-inclination angle of the lower boundary air guide tunnel 4 at different layer angles (unit: °)

[0062]

[0063] Combining Table 1 with the gradeability of the tunneling equipment, when the surface angle of Boundary Air Guide Tunnel 4 is 70°–75°, the pseudo-inclination angle of Boundary Air Guide Tunnel 4 is 16.06°–12.09°, meeting the gradeability requirements of the tunneling equipment. Based on this, the surface angle (ω+θ) of Boundary Air Guide Tunnel 4 is preliminarily determined to be 71°, and the pseudo-inclination angle γ of Boundary Air Guide Tunnel 4 is 15.27°. At this point, the angle between Boundary Air Guide Tunnel 4 and the working face transport tunnel 1 is 34°, and the angle between Boundary Air Guide Tunnel 4 and the working face return air tunnel 2 is 146°.

[0064] Step S03: Determine the length of the working surface and the shape and size of the tunnel section.

[0065] The following factors are mainly considered in determining the length of the continuous mining and filling working face:

[0066] ① To reduce the number of turns required by the excavation equipment, the length of the branch tunnel should be increased as much as possible; if the branch tunnel is too short, the excavation equipment will need to be moved too often, affecting production and work efficiency;

[0067] ② Ensure that the continuous transport system at the rear of the tunneling equipment has a certain length to increase tunneling efficiency;

[0068] ③The length of the branch tunnel affects the cost per ton of coal, including excavation fees, maintenance fees, and transportation fees.

[0069] Generally speaking, when the inclination angle of the branch tunnel is 8-12°, it is more reasonable to choose 100-160m for the calculated branch tunnel length.

[0070] Specifically in this embodiment, the length of the working face return air tunnel 2 is about 236m, the length of the working face transport tunnel 1 is about 306m, and the length of the boundary air guide tunnel 4 is about 190m.

[0071] Regarding the cross-sectional shape of the tunnel, in view of the difficulty in construction of special-shaped tunnel sections, poor surrounding rock stability, complex support methods, and the need for special tunneling equipment, the branch tunnels are selected with rectangular cross-sections, such as Figure 4 As shown in the figure, the height of the tunnel section is h and the width is l.

[0072] Specifically for this example, based on the monthly excavation progress of the fully mechanized tunneling equipment and relevant data, the width of the tunneling equipment (such as the EBZ260 roadheader and LWS600 continuous miner) is generally 3.0 to 3.8 meters, and sufficient support space is required. Therefore, the designed roadway width l is 4 meters. Based on this data, and taking into account factors such as the annual production of the working face, tunneling equipment size, coal loss rate, and safety risks, a 4×5 meter rectangular roadway cross-section is recommended. At this point, the ratio of the rock cross-sectional area in the branch roadway to the total cross-sectional area, n1, is 29.1%, and the ratio of the coal mass lost within the branch roadway mining height to the total coal mass within the branch roadway mining height, μ1, is 18.3%. Based on a monthly excavation progress of 400 to 450 meters for the fully mechanized tunneling equipment in the coal seam, the production capacity of the continuous mining and filling working face under the operating conditions of a single fully mechanized tunneling equipment set is approximately 117,000 to 131,000 tons / year. The filling is fully bonded to the surrounding rock of the roadway, and the risk of filling slippage is essentially non-existent.

[0073] Step S04: Arrange the working surface ventilation system.

[0074] Specifically, the working face forms full negative pressure ventilation with transport lane 1 and return air lane 2. Figure 5 During coal mining, full negative pressure ventilation and local fans 14 are used for ventilation. The continuous mining and filling working face ventilation system includes a fresh air flow route and an exhaust air flow route: the fresh air flow 12 passes through the section transport stone gate 5 and flows into the working face from the transport tunnel 1; the exhaust air 13 flows from the working face through the return air tunnel 2 to the section return air stone gate 6, and finally flows out from the return air shaft.

[0075] Figure 5 In addition, a branch tunnel 10 being filled and a branch tunnel 11 being excavated are shown.

[0076] Step S05: Determine the width of the interval coal pillars.

[0077] When the continuous mining and filling process described in the present invention is used, it is necessary to determine the width of the interval coal pillars of the working face, that is, the width of the interval area between the driving branch tunnel and the filling branch tunnel.

[0078] Firstly, the reasonable range of the width of the interval coal pillars is determined by theoretical calculation.

[0079] Assuming that the filling strength meets the stability requirements, it is only necessary to analyze the coal pillar width from the perspective of coal pillar bearing, that is, to analyze the above-mentioned coal pillar bearing stage.

[0080] According to the Obert-Duvall / Wang Formula coal pillar ultimate strength formula:

[0081]

[0082] Where, σ p is the ultimate strength of the coal pillar, MPa; σc is the uniaxial compressive strength of the coal body, MPa; w is the width of the coal pillar, m; h is the height of the coal pillar, m.

[0083] According to the safety factor comparison method:

[0084]

[0085] Where, P max is the maximum load on the top plate.

[0086] Right now:

[0087]

[0088] Where r is the bulk density of the overlying rock, KN / m 3 ; H is the depth of coal seam, m; is the internal friction angle of the coal seam; E is the elastic modulus of the coal seam; α is the inclination angle of the coal seam.

[0089] According to the above formula, the theoretical calculation value of the width of the interval coal pillar can be obtained.

[0090] Specifically in this embodiment, σ c The uniaxial compressive strength of the coal pillar is 15 MPa; h is the thickness of the coal seam, which is 2.72 m; r is the bulk density of the overlying rock layer, which is 25 kN / m 3 ; H is the depth of coal seam, which is 190m; is the internal friction angle of the coal seam, which is taken as 35°; E is the elastic modulus of the coal seam, which is taken as 0.5. Considering safety conditions, the above values ​​are all critical values.

[0091]

[0092] Calculations show that when the backfill is not connected to the top and the coal pillar bears the entire load, a coal pillar width of approximately 6m meets the stability requirements. Considering a safety factor of 1.5 to 3, the width of the interval coal pillar is preliminarily determined to be 9 to 18m.

[0093] Secondly, numerical simulation method is used to obtain the optimal value of the width of the interval coal pillars based on the stability of the surrounding rock.

[0094] Specifically in this embodiment, FLAC is used 3D Finite-difference numerical simulation software was used to study the stress and displacement evolution characteristics of the surrounding rock in different areas under three continuous mining and continuous filling modes with interval coal pillar widths of 8m, 12m, and 16m. The results showed that a 16m interval coal pillar width is more conducive to the synergistic bearing characteristics of the filling body and interval coal pillar structure. The filling body's bearing effect is more significant after the stope is filled, which is more conducive to further improving the stability of the stope and ensuring the safety of the roof and floor. Therefore, 16m was selected as the interval coal pillar width.

[0095] Step S06: adopt the method of continuous mining and continuous filling to carry out coal mining on the working face.

[0096] The working face adopts a double-slant layout. To improve the efficiency of coal mining and paste filling in the continuous mining and filling working face and prevent the paste setting time from affecting tunneling efficiency, the tunneling branch lanes are designed to be arranged parallel to the boundary air guide lanes and grouped. Based on the interval coal pillar width determined in the above steps and the cross-sectional width of the tunneling branch lanes, several branch lanes are divided into groups. Three groups form parallel mining and filling areas, and skip mining is used during tunneling and filling.

[0097] Take 5 branch lanes divided into a group as an example, Figure 6 As shown, first excavate a group of 1# tunnels (abbreviated as 1-1# tunnels, and the tunnels in other groups are named similarly to 1-1# tunnels). After the excavation of 1-1# tunnels is completed, excavate 2-1# tunnels and fill 1-1# tunnels at the same time; after the excavation of 2-1# tunnels is completed, excavate 3-1# tunnels and fill 2-1# tunnels at the same time, and so on, to carry out safe and efficient mining of the continuous mining and filling working face.

[0098] Specifically in this embodiment, for each excavation branch tunnel, the continuous mining and filling steps are as follows:

[0099] (1) Branch tunnel mining and bottom mining: First, a 4m×4m mining strip is excavated along the roof using a fully-mechanized tunneling machine, and a connecting tunnel is excavated to connect the return air tunnel and the transport tunnel. The second step is to extract the 1m thick bottom coal from the bottom plate by bottom mining. After mining and bottom mining, the total cross-section is 4m×5m.

[0100] (2) After the first branch tunnel is mined, the tunnel boring machine moves from the first branch tunnel through the transport tunnel 1 to the next branch tunnel separated by a certain width of coal pillars to continue mining. The two ends of the mined branch tunnel are promptly blocked and isolated using lightweight isolation brackets, and the entire space of the mined strip is filled with paste. After the filling solidifies for 28 days, the second round of filling mining is carried out. The branch tunnels on the sides of the separated coal pillars are mined and completely filled. The remaining coal pillars are mined and filled in three rounds, and the interval between each mining round is not less than 28 days.

[0101] by Figure 6 Taking the three excavation and filling groups divided in the middle as an example, the excavation order is: 1-1# branch lane → 2-1# branch lane → 3-1# branch lane → 1-2# branch lane → 2-2# branch lane → 3-2# ​​branch lane → 1-3# branch lane → 2-3# branch lane → 3-3# branch lane → 1-4# branch lane → 2-4# branch lane → 3-4# branch lane → 1-5# branch lane → 2-5# branch lane → 3-5# branch lane → 4-1# branch lane...; the order of filling branch lanes is the same as the order of excavating branch lanes, but filling needs to be carried out after the excavation of each branch lane is completed.

[0102] Regarding the support method for the excavated branch tunnels, specifically in this embodiment, the anchor bolt spacing at the top of the branch tunnel is 1.0m x 1.0m. Extended anchor bolts are used, with each bolt anchored with two resin anchors. When the side is in rock formation, the anchor bolt spacing can be appropriately increased to 1.2m. Airborne forward exploration beams are used for temporary support in the branch tunnels, while anchor mesh beams and anchor cables are used for permanent support. φ20 x 2000mm left-handed threaded steel anchors are used, with an anchoring force of no less than 105kN. The anchor bolt spacing is 1.0m x 1.0m, with each bolt anchored with two resin anchors. The anchor cable is a steel strand consisting of seven 7mm diameter steel wires, with a diameter of 18.9mm, a low relaxation grade, a strength of 1860MPa, a minimum breaking force of no less than 409kN, and a length of 6.5m. One MSCKb2360 cartridge and two MSZ2360 cartridges are used. Two anchor cables are installed in each row, with a spacing of 2.6m and a row spacing of 2m. The pre-tensioning force of the anchor cables shall not be less than 120kN, and the exposed length shall be 300mm.

[0103] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, no matter from which aspect, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the description of the embodiments described above, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the system claim may also be implemented by one unit or device through software or hardware. Words such as first, second, etc. are used to indicate names and do not indicate any particular order.

Claims

1. A method for continuous mining and backfilling of a group of steeply inclined and closely spaced coal seams with double pseudo-inclined slopes, comprising the following steps: According to the coal seam conditions, select a suitable continuous mining and continuous filling working face mining tunnel system; The transport tunnel, return air tunnel, and mining working face are all arranged in a pseudo-inclined manner; Determine the pseudo inclination angle η of the transport lane and the return air lane, and the pseudo inclination angle γ of the working surface according to the climbing ability of the equipment; Determine the width of the interval coal pillars; divide the working face into a number of parallel branch lanes according to a certain width; Coal mining at the working face is carried out using the continuous mining and filling method.

2. The method according to claim 1, characterized in that The transport tunnel and the return air tunnel are arranged in a downward pseudo-inclined manner, and the main mining method is downward mining; or they are arranged in an upward pseudo-inclined manner, and the main mining method is upward mining; downward mining is suitable for coal seams with complex hydrogeological conditions, groundwater threats, thin upper coal seam oxidation zones and low risk of filling paste sliding; upward mining is suitable for coal seams with low gas content and simple hydrogeological conditions, which require deep mining or have a tendency to rock burst.

3. The method according to claim 1, characterized in that A boundary air guide tunnel is arranged between the transport tunnel and the return air tunnel and parallel to the working face; a protective coal pillar is left between the boundary air guide tunnel and the working face.

4. The method according to claim 1, wherein The pseudo inclination angle γ of the working surface is: γ=arcsin(sinαcos(ω+θ)) Among them, γ is the pseudo-inclination angle of the working face, (°); α is the true inclination angle of the steeply inclined coal seam, (°); θ is the inclination adjustment angle of the first-type boundary air guide tunnel, (°); ω is the inclination adjustment angle of the second-type double-inclination mining working face, (°); (ω+θ) is the plane angle of the boundary air guide tunnel.

5. The method according to claim 1, characterized in that The working face uses the transport tunnel and return air tunnel to form full negative pressure ventilation for the entire working face; full negative pressure ventilation and local fans are used for ventilation during coal mining.

6. The method according to claim 1, characterized in that The reasonable range of interval coal pillar width is determined by theoretical calculation, and the optimal interval coal pillar width is determined according to the stability of the surrounding rock by numerical simulation.

7. The method according to claim 6, characterized in that According to the Obert-Duvall / Wang Formula coal pillar ultimate strength formula and safety factor comparison method, we can obtain: Among them, σ p is the ultimate strength of the coal pillar; P max is the maximum load on the top plate; σ c is the uniaxial compressive strength of the coal body; w is the width of the coal pillar; h is the height of the coal pillar; r is the bulk density of the overlying rock layer, KN / m 3 ; H is the depth of coal seam, m; is the internal friction angle of the coal seam; E is the elastic modulus of the coal seam; α is the inclination angle of the coal seam; And according to the above formula, the reasonable range of the width w of the interval coal pillar is obtained.

8. The method according to claim 1, characterized in that According to the width of the interval coal pillars and the cross-sectional width of the excavation branch tunnels, several branch tunnels are divided into one group, with 3 groups as parallel mining and filling areas, and a skip mining method is adopted during the excavation and filling process.

Images