Structural filling mining method using combined stone masonry, grouting and shotcreting behind gabion

Abstract

The present invention discloses a structured filling and mining method combining gabion masonry, grouting and shotcreting behind the working face, which belongs to the technical field of coal mining. The present invention processes the loose gangue generated by the working face into a standardized box-shaped gabion gangue masonry body, stacks and lays it into a dry stone strip wall through the lifting and stacking device of the filling-specific hydraulic support, and simultaneously adopts the combined reinforcement method of "external shotcreting + internal grouting" to consolidate the dry stone strip wall into a whole, forming several parallel strip-type filling walls behind the working face. The present invention proposes a continuous mining and filling mining method with a high degree of mechanization and integration. During the advancement of the working face, the gangue is not lifted to the well and is recycled. The filling method is partial filling, which can simultaneously solve the two technical problems of high filling cost and gangue solid waste pollution in the context of green mines; various carbon storage and negative carbon materials can be thrown and stacked in the formed underground space for comprehensive utilization, helping to realize "zero carbon" mines and make secondary use of the goaf.

Description

Technical Field

[0001] The invention relates to a continuous mining and filling coal mine structural filling mining method, in particular to a structure filling mining method combining stone masonry, grouting and spraying behind a frame, and belongs to the technical field of coal mining. Background Art

[0002] Under the "dual carbon" goal, green mine construction has put forward higher requirements for the filling of waste rock and solid waste in underground coal mining, as well as surface subsidence. In this context, waste rock filling mining has gradually become an effective path for green mine construction. The existing full mining and full filling mining method has a good effect in controlling overburden deformation and surface subsidence. However, paste filling and other methods require a large amount of cement and other cementing materials, which are expensive and seriously restrict the large-scale application of filling mining. In addition, the proportion of solid waste generated by coal mines themselves is relatively small. The amount of coal gangue generated is only 15% to 20% of the amount of coal mined, and the amount of fly ash generated by power plants is only 20% to 30% of the amount of coal burned. The overall filling potential is less than 50% (Xu Jialin, Xuan Dayang, Zhu Weibing, et al. Research and practice of partial filling coal mining technology [J]. Journal of China Coal Society, 2015, 40(6): 1303-1312.). In addition, full filling requires filling the entire goaf. Due to different geological conditions and coal mining methods, the filling effect is difficult to guarantee. In this context, some researchers have proposed a structural filling approach (Feng Guorui, Du Xianjie, Guo Yuxia, et al. Basic Theory of Structural Filling Mining and Concept of Underground Space Utilization [J]. Journal of China Coal Society, 2019, 44(01):74-84.) to solve the problem of high cost caused by excessive demand for filling materials and excessively high requirements for natural strength indicators during the entire filling process. Structural filling is based on the distribution of coal seams and the characteristics of their surrounding rocks. Through pre-mining planning and solid waste resource utilization, structural filling bodies such as column (pier), strip (wall) or box shapes are arranged in key locations of the goaf to achieve the goal of controlling rock stratum movement and surface subsidence. Structural filling has proposed a new technical approach for efficiently utilizing solid waste resources in mining areas, reducing filling costs, improving filling materials and processes, and realizing the reuse of underground mining space.

[0003] In the development of mining technology, the fully mechanized caving and mining processes and technical equipment for thick coal seams have become increasingly mature and complete, but the development of mechanized equipment specifically for backfilling has been slow. In addition, most existing local backfilling mining methods require the construction of additional partition walls, which wastes manpower and material resources, is costly, inefficient, and also affects the backfilling effect. In particular, the mechanized "continuous mining and backfilling" technology system related to structural backfilling needs further improvement and development. At present, the premise of mining design is to ensure the backfilling effect while the waste rock is not lifted up to the surface during mining, and to achieve efficient support for the roof rock layer of the goaf. Therefore, it is urgent to propose a cost-effective and highly mechanized "continuous mining and backfilling" technology system based on waste rock solid waste. Summary of the Invention

[0004] The present invention aims to provide a structural filling mining method that combines post-mount gabion masonry, grouting, and shotcreting. This method is guided by the principle of structural filling and uses gangue generated at the working face as the primary aggregate. The loose coal gangue is loaded into a designed box-type structural gabion box and sealed. The loaded gabions are then stacked to form a dry-stone strip wall. Simultaneously, the loose gangue in the dry-stone strip wall is consolidated into a whole through a combined reinforcement method of "external shotcreting + internal grouting," forming several parallel strip filling bodies behind the working face. The filling effect is ensured while the gangue is not lifted up the shaft, thereby achieving efficient support for the roof rock strata of the goaf.

[0005] The present invention provides a structural filling mining method combining stone masonry, grouting and spraying behind a gabion, which specifically comprises the following steps:

[0006] (1) According to the geological conditions of the working face, the thickness of the coal seam, the amount of gangue at the working face, the movement of the roof rock layer and the advancement speed of the working face, the height h of the filling body, the width a of the filling body, the spacing b between the filling bodies and the filling rate V of the goaf strip filling are determined; at the same time, a filling chamber is arranged underground, and the coal gangue produced after the underground sorting is piled in the filling chamber.

[0007] (2) Design the length L1, width a1 and height h1 of the box-shaped gabion according to the parameters determined in step (1); determine the material, mesh size and wire diameter of the box-shaped gabion according to the strength, average particle size and shape of the sorted gangue.

[0008] Preferably, the width of the box-shaped gabion mesh is h1=H / n (n is an integer, ensuring that the strip filling body is fully connected to the top after masonry), and h1=0.5*a1=0.25*L1.

[0009] (3) With the completion of the construction of the coal seam transport tunnel, the return air tunnel and the opening of the cutting hole, the coal mining machine, the hydraulic support and the special hydraulic support for filling are transported to the working face for arrangement and erection, wherein the hydraulic support at the position of the strip filling body designed in step (1) is the special hydraulic support for filling; when the width of the filling body is greater than the width of the special hydraulic support for filling, multiple special hydraulic supports for filling are arranged in parallel; when the width of the filling body is less than the width of a single special hydraulic support for filling, one special hydraulic support for filling is arranged.

[0010] (4) The gabion mesh is transported to the underground filling tunnel and processed into a box-shaped gabion mesh of the size designed in step (2) underground. The waste rock sorted underground is loaded into the gabion mesh and sealed.

[0011] (5) The gabion mesh filled with gangue is transported to the rear of the hydraulic support of the mining working face by a belt conveyor, and the gabion mesh masonry blocks are transported to the position of the filling special hydraulic support arranged in step (3) by the gabion mesh masonry block transfer belt conveyor arranged behind the hydraulic support;

[0012] The special hydraulic support for filling is moved while mining, and the space after mining is filled with blocks.

[0013] (6) Under the protection of the special hydraulic support for filling, the loaded gabion masonry blocks are lifted and stacked neatly through the lifting and stacking device of the special hydraulic support for filling to form a dry stone strip wall.

[0014] (7) During the stacking of the gabion masonry blocks filled in step (6), a grouting pipe is left at the center of the dry stone strip wall parallel to the coal mining working face. As the mining working face advances, the dry stone strip wall is stacked and extended, and the grouting pipe is connected and extended at the same time. Generally, the working face is hundreds of meters long, so the grouting pipe is designed to be connected in short pipes, which are connected and extended according to the length of the working face.

[0015] (8) Cement mortar is sprayed on both sides of the dry stone strip wall formed by stacking by filling the special hydraulic support with a spraying pipe. The purpose is to form a thin cement mortar sealing layer on the surface of the dry stone strip wall. At the same time, compressed air is used to spray cement mortar into the surface of the dry stone strip wall and the pores of the surface broken gangue, so as to consolidate the surface loose gangue into a whole and form preliminary support on both sides of the dry stone strip wall.

[0016] (9) After the sprayed cement mortar solidifies, grouting is performed through the grouting pipe connected in step (7) into the interior of the dry stone strip wall formed by stacking the loaded gabion masonry blocks. The grouting liquid diffuses from the center outwards and gradually fills the pores, consolidating the dry stone strip wall into a whole. The cement mortar sealing layer formed by spraying on both sides of the dry stone strip wall ensures the airtightness during the grouting process and avoids problems such as slurry leakage. At the same time, the slurry can diffuse into the gap between the top of the dry stone strip wall and the top plate, ensuring the top connection effect of the stone strip wall.

[0017] (10) After the coal cutter completes a round of coal cutting, the hydraulic support moves forward and the transfer belt conveyor behind the support moves forward accordingly. Under the cover of the cantilever plate structure formed by the roof, steps (5) to (10) are repeated to gradually complete the extension of the gabion masonry wall and the "internal grouting + external spraying" combination reinforcement of the dry stone strip wall. A strip filling body is formed behind the hydraulic support, and the filling work of the goaf is gradually completed.

[0018] (11) After the slurry inside the strip filling solidifies, several parallel strip fillings are formed in the goaf. After the overlying roof collapses periodically, timely attention should be paid to the compression and bearing capacity of the strip filling.

[0019] When the compression of the filling body in the roof collapse area is too high and the bearing capacity is insufficient, during the subsequent strip filling body construction process, during the stacking of the loaded gabion masonry blocks, tension anchor rods are arranged every 2m~10m along the length direction of the filling body; specifically, tension anchor rods are set in the middle of the gabion masonry blocks, that is, in the width direction of the dry stone strip wall, through the entire wall, and the deformation of the strip filling body in the width direction is constrained by the trays at both ends of the tension anchor rods (the trays are set on the side of the wall), and at the same time, the area of the anchor rod trays on both sides of the wall is increased to further control the deformation of the formed strip filling body and enhance the bearing capacity.

[0020] In the above method, the filling-specific hydraulic support includes a hydraulic support body, a lifting and stacking device, a grouting device and a baffle. The support top beam is extended backward on the basis of the hydraulic support body to protect the transportation of gabion masonry blocks during on-site construction; a lifting and stacking device, a grouting device and a support baffle are arranged behind the hydraulic support body, and the lifting and stacking device moves along the filling direction through the lifting and stacking device slide rail arranged below the support top beam; the grouting device includes a shotcrete pipe and a shotcrete pipe slide rail; a support baffle is provided in the vertical direction behind the hydraulic support body, a shotcrete pipe slide rail is provided on the support baffle in the vertical direction, and a shotcrete pipe is provided in the vertical direction along the shotcrete pipe slide rail; the shotcrete pipe is arranged in the horizontal direction.

[0021] In the above method, after the box-shaped gabion is processed into the designed size, it is lined with a layer of dense nylon mesh before filling the gangue underground to ensure that small-sized particles generated by the bite friction of the internal loose gangue leak out of the gabion.

[0022] In the above method, in step (1), the height of the strip filling body is determined comprehensively based on the gangue production of the working face and the height of the goaf, so as to ensure that all the gangue produced by the working face is utilized and the purpose of preventing the gangue from being lifted into the well is achieved.

[0023] Specifically, the amount of gangue at the working face was estimated based on coal production, assuming gangue production was 15% to 20% of the coal extraction rate. The gangue volume was estimated using a coefficient of expansion of 1.5. The height h, width a, and spacing b between the goaf strip fillings were determined based on the goaf height H and the goaf width A, i.e., H = h, with a / (a + b) = 0.2-0.3. The filling rate V was determined based on the working face advance speed, which was required to be consistent with the working face advance speed.

[0024] In the above method, in step (2), the size of the box-shaped gabion is determined according to the size and shape of the gangue generated by the underground sorting, ensuring that the size of the gangue filled in the box-shaped gabion is greater than 1.5 times the mesh size; during the mechanical filling process, the proportion of loose gangue of various sizes should be screened and controlled to ensure that the aggregate is well graded and the filling gangue does not leak out or exceed the mesh.

[0025] In the above method, the length L1, width a1 and height h1 of the box-shaped gabion are determined according to the filling body width a and the goaf height H determined in step (1), and the requirements are: the goaf height H is equal to the goaf strip filling body height h, and the goaf strip filling body height h / gabion height h1 is an integer; the filling body width a / gabion width a1 is an integer; the length L1 of the gabion is determined according to the determined gabion height h1 and gabion width a1, and the requirement is that the gabion length L1: width a1: height h1 = 4:2:1, to ensure the feasibility of staggered stacking during the stacking of the filled gabion masonry blocks.

[0026] In the above method, in step (2), the bearing capacity requirements of the gangue strip wall are determined based on the strength of the underground sorted gangue and the migration of the overlying rock strata. Combined with the strength of the single gabion gangue block after grouting determined by laboratory tests, the type of gabion and the wire diameter of the gabion are adjusted. The gabion type can be selected from low-carbon steel wire, lead wire gabion, plastic-coated gabion, galvanized gabion, etc. When there is a high demand for the strength of the strip filling, reinforced gabion is selected.

[0027] In the above method, the gangue in step (4) is loaded by mechanical equipment, and the gabion mesh is vibrated during the loading process to ensure that the gangue filler inside is fully contacted. It is required that after the gangue filler is filled and sealed, the internal void ratio is less than 35% to avoid excessive slurry demand during the subsequent grouting process, ensuring the bearing capacity of the strip filling body while improving its economy as much as possible. Because the gangue is mostly polygonal crushed stone, it can fit well with each other in the box-shaped gabion mesh, and the bearing capacity of the filling body is enhanced by the bite and friction between the loose gangue blocks.

[0028] In the above method, during the bulk gangue filling process in step (4), large gangue pieces that are too large to fit into the box-shaped gabion mesh are transported to the goaf and thrown into the goaf between the strip filling bodies for processing.

[0029] In the above method, the length of the grouting pipeline in step (7) is comprehensively determined based on the working face advancement speed, the top control distance and the initial setting time of the grouting material, to ensure that as the working face advances, the grouting work is completed before the overlying roof periodically collapses and the slurry is completely solidified and has the bearing capacity. At the same time, the safety distance between the grouting area and the dry masonry strip area being stacked and placed is required to match the grouting pressure to avoid slurry running along the direction of the strip filling or insufficient slurry diffusion; specifically, when the safety distance between the grouting area and the dry masonry strip area being stacked and placed is too long, the space required for grouting is too large, and the grouting pressure is too small, which will make it difficult for the slurry to diffuse into every pore; when the safety distance is too short, the space required for grouting is too small, and the grouting slurry will run from the stacked masonry blocks.

[0030] In the above method, when the grouting efficiency of a grouting pipe arranged inside the dry stone strip wall does not match the working surface advancement efficiency, or the slurry cannot be completely diffused to the dead corner of the designed grouting area, the number of grouting pipes should be increased, that is, multiple grouting pipes should be evenly arranged along the center line of the dry stone strip wall parallel to the working surface direction.

[0031] In the above method, the aggregate in the cement mortar during the shotcrete process is gangue debris and powder with a particle diameter of less than 1 cm from underground gangue. The mass ratio of the cement mortar is: cement: aggregate: water = 1-1.2: 3-3.5: 0.5-0.6. The accelerator dosage is 3%-5% of the total slurry mass. The operating air pressure during the shotcrete process is greater than 0.5 MPa, and the shotcrete thickness is greater than 40 mm.

[0032] In the above method, the box-shaped gabion mesh and nylon mesh lining act as hanging nets during the shotcrete process, ensuring the adhesion of the surface grout during the shotcrete process. After shotcrete grouting, the loose rock within a depth of 3 cm on the surface of the dry stone strip wall solidifies into a single piece, with good interlocking and interlocking between the rock blocks. Together with the solidified cement mortar layer on the wall surface, it acts as a "template" for the side surface of the wall, providing a confined space for internal grouting and preventing grout from running along the sides of the wall during the shotcrete construction process.

[0033] In the above method, combined with existing mining experience, the amount of coal gangue produced is 15% to 20% of the coal mining volume. The volume of gangue at the working face is estimated with a crushing expansion coefficient of 1.5. It is estimated that the volume of the strip filling body formed after grouting in step (9) and spraying in step (8) accounts for 25% to 35% of the volume of the entire goaf. That is, the goaf filling rate after continuous mining and filling using this method is 25% to 35%. At the same time, regular underground spaces separated by strip filling bodies are formed in the goaf, accounting for 65% to 75% of the volume of the entire mined space. Various carbon storage and negative carbon materials can be thrown and piled in the formed underground spaces for utilization, helping to achieve "zero carbon" mines.

[0034] In the above method, the length of the tension anchor rods left inside the wall in step (11) matches the width a of the filling body designed in step (1). Generally, the length of the tension anchor rods is set to be 1.05 to 1.15 times the width a of the filling body. The installation size of the anchor rod tray is reserved to ensure that the lateral deformation of the strip gangue can be effectively restrained under the constraint of the large-area anchor rod trays at both ends, thereby enhancing the integrity of the gabion gangue wall after grouting. The side length of the designed rectangular anchor rod tray is similar to the height of the box-shaped gabion mesh, ensuring that the rectangular anchor rod tray can restrain the sliding and dislocation of the filled gabion mesh masonry blocks that the anchor rods directly contact, thereby enhancing the integrity and bearing performance of the strip filling body.

[0035] Beneficial effects of the present invention:

[0036] (1) The present invention processes the loose gangue generated on the working surface into a standardized box-shaped gabion gangue masonry body, giving full play to the interlocking friction between the irregular loose gangue blocks to strengthen the bearing capacity of the strip filling body, and stacking them into a dry stone strip wall through the lifting and stacking device of the filling-specific hydraulic support. At the same time, the dry stone strip wall is consolidated into a whole through the combined reinforcement method of "external spraying + internal grouting", forming several parallel strip filling walls behind the working surface.

[0037] (2) The present invention proposes a continuous mining and filling method with a high degree of mechanization and integration. During the advancement of the working face, the waste rock is not lifted up to the well and is recycled. The construction process is connected reasonably, which can effectively save manpower and material resources and simplify the construction method. The filling work follows the mining working face, and the two are promoted in coordination to fill the entire section at one time, strictly controlling the settlement of the overlying rock strata and effectively controlling surface subsidence.

[0038] (3) The present invention realizes the continuous mining and filling of waste rock without lifting it to the well during the coal mining process, which can significantly save the cost of lifting the waste rock to the well and discharging it to the outside. The filling method is partial filling, and the coarse aggregate used for filling is mainly underground waste rock and collapsed direct roof and false roof, and the filling rate is only 25%~35%. It can simultaneously solve the two technical problems of high filling cost and waste rock solid waste pollution in the context of green mining.

[0039] (4) For coal seams with good rock conditions, the goaf that has been filled can obtain neat underground spaces divided by strip filling bodies. Various carbon storage and negative carbon materials can be thrown and piled in the formed underground space for comprehensive utilization, helping to realize "zero carbon" mines and make secondary use of the goaf. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the special hydraulic support for filling used in the present invention;

[0041] Figure 2 This is a schematic diagram of the raw materials and processing process of gabion masonry blocks;

[0042] Figure 3 This is a schematic diagram of the implementation process of the structural filling mining method combining stone masonry, grouting and shotcreting behind the gabion;

[0043] Figure 4 It is a cross-sectional schematic diagram of the completed strip filling body parallel to the coal mining working face;

[0044] Figure 5 This is a schematic cross-sectional view of a dry stone wall under construction parallel to the coal mining face;

[0045] Figure 6 It is a schematic diagram of the arrangement of the filling mining working face during the advancement process;

[0046] In the figure: 1-special hydraulic support for filling, 2-lifting and stacking device, 3-lifting and stacking device slide rail, 4-grouting pipe, 5-grouting pipe slide rail, 6-support baffle, 7-bulk gangue, 8-box-shaped gabion, 9-box-shaped gabion lined with nylon mesh, 10-filled gabion masonry blocks, 11-tension anchor tray, 12-tension anchor, 13-spraying layer on the surface of dry stone wall, 14-grouting pipe, 15-transfer belt conveyor, 16-goaf, 17-strip filling body, 18-hydraulic support, 19-coal mining working face. DETAILED DESCRIPTION

[0047] The following examples are intended to illustrate and explain the present invention, but are not intended to limit the scope of the present invention.

[0048] In order to have a clearer understanding of the technical objectives, features and effects of the present invention, the method of freezing the accumulated water between the coal pillars in the goaf and re-mining the goaf coal seam will be further described in detail with reference to the accompanying drawings.

[0049] This embodiment provides a structural filling mining method combining stone masonry, grouting, and shotcreting behind the gabion, specifically comprising the following steps:

[0050] (1) According to the geological conditions of the working face, the thickness of the coal seam, the amount of gangue at the working face, the movement of the roof rock layer and the advancement speed of the working face, the height h of the filling body, the width a of the filling body, the spacing b between the filling bodies and the filling rate V of the goaf strip filling are determined; at the same time, a filling chamber is arranged underground, and the coal gangue produced after the underground sorting is piled in the filling chamber.

[0051] (2) Design the length L1, width a1 and height h1 of the box-shaped gabion according to the parameters determined in step (1); determine the material, mesh size and wire diameter of the box-shaped gabion according to the strength, average particle size and shape of the sorted gangue.

[0052] Preferably, the width of the box-shaped gabion mesh is h1=H / n (n is an integer, ensuring that the strip filling body is fully connected to the top after masonry), and h1=0.5*a1=0.25*L1.

[0053] (3) With the completion of the construction of the coal seam transport tunnel, the return air tunnel and the opening of the cutting hole, the coal mining machine, the hydraulic support and the special hydraulic support for filling are transported to the working face for arrangement and erection, wherein the hydraulic support at the position of the strip filling body designed in step (1) is the special hydraulic support for filling; when the width of the filling body is greater than the width of the special hydraulic support for filling, multiple special hydraulic supports for filling are arranged in parallel; when the width of the filling body is less than the width of a single special hydraulic support for filling, one special hydraulic support for filling is arranged.

[0054] (4) The gabion mesh is transported to the underground filling tunnel and processed into a box-shaped gabion mesh of the size designed in step (2) underground. The waste rock sorted underground is loaded into the gabion mesh and sealed.

[0055] (5) The gabion mesh filled with gangue is transported to the rear of the hydraulic support of the mining working face by a belt conveyor, and the gabion mesh masonry blocks are transported to the position of the filling special hydraulic support arranged in step (3) by the gabion mesh masonry block transfer belt conveyor arranged behind the hydraulic support;

[0056] The special hydraulic support for filling is moved while mining, and the space after mining is filled with blocks.

[0057] (6) Under the protection of the special hydraulic support for filling, the loaded gabion masonry blocks are lifted and stacked neatly through the lifting and stacking device of the special hydraulic support for filling to form a dry stone strip wall.

[0058] (7) During the stacking of the gabion masonry blocks filled in step (6), a grouting pipe is left at the center of the dry stone strip wall parallel to the coal mining working face. As the mining working face advances, the dry stone strip wall is stacked and extended, and the grouting pipe is connected and extended at the same time. Generally, the working face is hundreds of meters long, so the grouting pipe is designed to be connected in short pipes, which are connected and extended according to the length of the working face.

[0059] (8) Cement mortar is sprayed on both sides of the dry stone strip wall formed by stacking by filling the special hydraulic support with a spraying pipe. The purpose is to form a thin cement mortar sealing layer on the surface of the dry stone strip wall. At the same time, compressed air is used to spray cement mortar into the surface of the dry stone strip wall and the pores of the surface broken gangue, so as to consolidate the surface loose gangue into a whole and form preliminary support on both sides of the dry stone strip wall.

[0060] (9) After the sprayed cement mortar solidifies, grouting is performed through the grouting pipe connected in step (7) into the interior of the dry stone strip wall formed by stacking the loaded gabion masonry blocks. The grouting liquid diffuses from the center outwards and gradually fills the pores, consolidating the dry stone strip wall into a whole. The cement mortar sealing layer formed by spraying on both sides of the dry stone strip wall ensures the airtightness during the grouting process and avoids problems such as slurry leakage. At the same time, the slurry can diffuse into the gap between the top of the dry stone strip wall and the top plate, ensuring the top connection effect of the stone strip wall.

[0061] (10) After the coal cutter completes a round of coal cutting, the hydraulic support moves forward and the transfer belt conveyor behind the support moves forward accordingly. Under the cover of the cantilever plate structure formed by the roof, steps (5) to (10) are repeated to gradually complete the extension of the gabion masonry wall and the "internal grouting + external spraying" combination reinforcement of the dry stone strip wall. A strip filling body is formed behind the hydraulic support, and the filling work of the goaf is gradually completed.

[0062] (11) After the slurry inside the strip filling solidifies, several parallel strip fillings are formed in the goaf. After the overlying roof collapses periodically, timely attention should be paid to the compression and bearing capacity of the strip filling.

[0063] When the compression of the filling body in the roof collapse area is too high and the bearing capacity is insufficient, during the subsequent strip filling body construction process, during the stacking of the loaded gabion masonry blocks, tension anchor rods are arranged every 2m~10m along the length direction of the filling body; specifically, tension anchor rods are set in the middle of the gabion masonry blocks, that is, in the width direction of the dry stone strip wall, through the entire wall, and the compression deformation of the strip filling body is constrained by the trays at both ends of the tension anchor rods (the trays are set on the side of the wall), and at the same time, the area of the anchor trays on both sides of the wall is increased to further control the deformation of the formed strip filling body and enhance the bearing capacity.

[0064] In the above method, after the box-shaped gabion is processed into the designed size, it is lined with a layer of dense nylon mesh before filling the gangue underground to ensure that small-sized particles generated by the bite friction of the internal loose gangue leak out of the gabion.

[0065] In the above method, in step (1), the height of the strip filling body is determined based on the gangue production of the working face and the height of the goaf, ensuring that all the gangue produced by the working face is utilized and achieving the goal of not bringing the gangue up to the wellbore. Specifically, based on the gangue production being 15% to 20% of the coal mining volume, the gangue volume of the working face is estimated based on the coal production of the working face; the gangue volume of the working face is estimated based on the expansion coefficient of 1.5. The filling body height h, filling body width a, and spacing b between filling bodies of the goaf strip filling are determined based on the goaf height H and the working face width A, that is, H = h, a / (a + b) = 0.2 to 0.3; the filling rate V is determined based on the working face advancement speed, and the filling rate is required to be consistent with the working face advancement speed.

[0066] In the above method, in step (2), the size of the box-shaped gabion is determined according to the size and shape of the gangue generated by the underground sorting, ensuring that the size of the gangue filled in the box-shaped gabion is greater than 1.5 times the mesh size; during the mechanical filling process, the proportion of loose gangue of various sizes should be screened and controlled to ensure that the aggregate is well graded and the filling gangue does not leak out or exceed the mesh.

[0067] In the above method, the length L1, width a1 and height h1 of the box-shaped gabion are determined according to the filling body width a and the goaf height H determined in step (1), and the requirements are: the goaf height H is equal to the goaf strip filling body height h, and the goaf strip filling body height h / gabion height h1 is an integer; the filling body width a / gabion width a1 is an integer; the length L1 of the gabion is determined according to the determined gabion height h1 and gabion width a1, and the requirement is that the gabion length L1: width a1: height h1 = 4:2:1, to ensure the feasibility of staggered stacking during the stacking of the filled gabion masonry blocks.

[0068] In the above method, in step (2), the bearing capacity requirements of the gangue strip wall are determined based on the strength of the underground sorted gangue and the migration of the overlying rock strata. Combined with the strength of the single gabion gangue block after grouting determined by laboratory tests, the type of gabion and the wire diameter of the gabion are adjusted. The gabion type can be selected from low-carbon steel wire, lead wire gabion, plastic-coated gabion, galvanized gabion, etc. When there is a high demand for the strength of the strip filling, reinforced gabion is selected.

[0069] In the above method, the length of the grouting pipeline in step (7) is comprehensively determined based on the working face advancement speed, the top control distance and the initial setting time of the grouting material, to ensure that as the working face advances, the grouting work is completed before the overlying roof periodically collapses and the slurry is completely solidified and has the bearing capacity. At the same time, the safety distance between the grouting area and the dry masonry strip area being stacked and placed is required to match the grouting pressure to avoid slurry running along the direction of the strip filling or insufficient slurry diffusion; specifically, when the safety distance between the grouting area and the dry masonry strip area being stacked and placed is too long, the space required for grouting is too large, and the grouting pressure is too small, which will make it difficult for the slurry to diffuse into every pore; when the safety distance is too short, the space required for grouting is too small, and the grouting slurry will run from the stacked masonry blocks. In the above method, when the grouting efficiency of a grouting pipe arranged inside the dry stone strip wall does not match the working surface advancement efficiency, or the slurry cannot be completely diffused to the dead corner of the designed grouting area, the number of grouting pipes should be increased, that is, multiple grouting pipes should be evenly arranged along the center line of the dry stone strip wall parallel to the working surface direction.

[0070] In the above method, combined with existing mining experience, the amount of coal gangue produced is 15% to 20% of the coal mining volume. The volume of gangue at the working face is estimated with a crushing expansion coefficient of 1.5. It is estimated that the volume of the strip filling body formed after grouting in step (9) and spraying in step (8) accounts for 25% to 35% of the volume of the entire goaf. That is, the goaf filling rate after continuous mining and filling using this method is 25% to 35%. At the same time, regular underground spaces separated by strip filling bodies are formed in the goaf, accounting for 65% to 75% of the volume of the entire mined space. Various carbon storage and negative carbon materials can be thrown and piled in the formed underground spaces for utilization, helping to achieve "zero carbon" mines.

[0071] The average thickness of the 8# coal seam in a certain mine is 5.25m. In response to the green mine construction goals of the competent authorities, it is required to effectively control surface subsidence and scientifically handle problems such as waste rock dumps. After scientific demonstration, the mining area expects to carry out backfill mining at the 18403 working face and make full use of the waste rock produced by the working face. The average advancement rate of the adjacent working face of the 8# coal seam is 4m / d, and the output of coal gangue after sorting is about 15% of the coal resource output. In view of the above situation, the implementation process of the present invention is further described in detail below with reference to the accompanying drawings. The specific implementation steps are as follows:

[0072] a. Based on the hydrogeological conditions and coal seam thickness of the 18403 working face, combined with the amount of gangue from the adjacent working face of the mined 8# coal seam, the movement of the roof rock layer, and the working face advancement speed, the height h of the strip filling body 17 is determined to be 5.25m, the filling body width a=9m, the spacing between the strip filling bodies b=30m, and the filling rate is consistent with the working face advancement speed, V=4m / d. Ensure that all the gangue generated by the working face is utilized to achieve the goal of not bringing the gangue up to the mine. During the working face advancement process, coal gangue is sorted underground, and the gangue generated by the sorting is transported to the filling chamber arranged underground;

[0073] b. According to the width of the strip filling body 17 and the filling rate in step a, the length L1=1.5m, width a1=0.75m and height h1=0.375m of the gabion are determined. The number of vertically stacked strip filling bodies is determined to be 14, which ensures the feasibility of staggered stacking in the process of stacking the gabion stones to form a strip wall. According to the strength, average particle size and shape of the sorted gangue, the material of the hexagonal gabion (with hexagonal mesh) is determined to be galvanized steel wire, the wire diameter of the gabion is 4.0mm, and the side length of the mesh of the hexagonal gabion is 0.12m. The processed gabion is built with a dense woven nylon mesh cushion layer to prevent the internal gangue from leaking out or exceeding the mesh body, and at the same time acts as a hanging net during the spraying process of the gangue strip wall after stacking;

[0074] c. With the completion of the construction of the coal seam transport tunnel, return air tunnel and opening of the cutting hole, the coal mining machine and the conventional hydraulic support 18 and the special hydraulic support 1 for filling are transported to the working face for arrangement and erection. The support at the position of the strip filling body 17 designed in step a is the special hydraulic support 1 for filling, such as Figure 1 As shown. The dedicated filling hydraulic support 1 comprises a hydraulic support body, a lifting and stacking device 2, a grouting device, and a support baffle 6. The support top beam extends backward from the hydraulic support body to protect the transportation of gabion masonry blocks during on-site construction. The lifting and stacking device 2, the grouting device, and the support baffle 6 are arranged behind the hydraulic support body. The lifting and stacking device 2 moves in the filling direction via a lifting and stacking device slide 3 provided below the support top beam. The grouting device comprises a shotcrete pipe 4 and a shotcrete pipe slide 5. A support baffle 6 is provided vertically behind the hydraulic support body. A shotcrete pipe slide 5 is provided vertically on the support baffle 6. A shotcrete pipe 4 is provided vertically along the shotcrete pipe slide 5. The shotcrete pipe 4 is arranged horizontally.

[0075] d. Process the gabion mesh into a box-shaped gabion mesh 8 of the size designed in step b on the ground, transport it to the underground filling chamber, line the inner part of the box-shaped gabion mesh 8 transported to the underground with a dense nylon mesh, and process it into a box-shaped gabion mesh lined with nylon mesh 9, and fill the loose gangue 7 produced after sorting underground into the box-shaped gabion mesh lined with nylon mesh 9 through mechanical equipment and seal it to obtain a filled gabion mesh masonry block 10, as shown Figure 2As shown. During the filling process, the gabion mesh is vibrated to ensure the density of the internal gangue filler, ensure that the internal gangue filler is fully contacted, give full play to the friction and interlocking properties between the loose gangue blocks, control the internal void ratio to less than 35%, avoid excessive slurry demand during the subsequent grouting process, ensure the bearing capacity of the strip filling body while maximizing its economic efficiency. Because the gangue is mostly polygonal crushed stone, it can fit well with each other in the box-shaped gabion mesh, and the bite and friction between the loose gangue blocks strengthen the bearing capacity of the filling body;

[0076] e. Transport the loaded gabion masonry blocks 10 to the coal mining face 19 via a belt conveyor, and transport the loaded gabion masonry blocks 10 to the position of the dedicated filling hydraulic support 1 arranged in step c via a transfer belt conveyor 15 arranged behind the hydraulic support 18;

[0077] f. Under the protection of the filling hydraulic support 1, the filled gabion masonry blocks 10 are lifted and stacked by the lifting and stacking device 2 and the lifting and stacking device slide rail 3 of the filling hydraulic support 1 to form a dry stone strip wall. Figure 3 As shown, during transportation, the dedicated hydraulic support baffles 6 for filling effectively prevent the loaded gabion masonry blocks 10 from shifting or sliding. As the loaded gabion masonry blocks 10 are transported to the goaf 16 via the transfer belt conveyor 15, large pieces of waste rock that are too large to fit into the box-shaped gabions are simultaneously transported to the goaf 16 and thrown into the empty space between the strip filling blocks 17 in the goaf 16 for processing.

[0078] g. During the stacking process of the gabion masonry blocks 10 filled in step f, six grouting pipes 4 are left in the middle position of the stone wall parallel to the cross section of the coal mining working face. As the coal mining working face 19 advances, the dry stone strip wall is stacked and extended, and the grouting pipes 4 are connected and extended;

[0079] h. Spray cement mortar onto both sides of the dry stone strip wall formed by stacking in step f by filling the grouting pipe 4 and the grouting pipe slide 5 matched with the special hydraulic support 1, consolidate the loose stone masonry on the surface of the dry stone strip wall into a whole, and form a preliminary support on both sides of the dry stone strip wall. During the spraying process, the gabion mesh and the nylon mesh of the lining can act as a hanging net to enhance the adhesion effect of the surface slurry during the spraying process. The aggregate in the cement mortar during the spraying process is gangue debris and powder with a particle diameter of less than 1 cm. The corresponding slurry mass ratio is: cement: aggregate: water = 1: 3: 0.6, and the dosage of the accelerator is 5% of the total mass. The working wind pressure during the spraying process is greater than 0.5MPa, and the average thickness of the spraying is 50mm;

[0080] i. After the sprayed cement mortar solidifies, the gangue within a depth of 3 cm on the surface of the dry stone strip wall solidifies into a whole. Together with the sprayed mortar layer 13 on the surface of the dry stone wall, it provides a closed space for internal grouting construction, acting as a "grouting template" on both sides of the dry stone wall, preventing grout from running along the sides of the wall during grouting construction, while ensuring the top connection effect of the stone strip wall. Grouting is injected into the stacked dry stone strip wall through the grouting pipe 4 connected in step g, consolidating the dry stone strip wall into a whole. Figure 4 and Figure 5 Ensure that the slurry solidifies and has the bearing capacity before the roof collapses periodically;

[0081] j. After the coal cutter completes a round of coal cutting, the hydraulic support 18 and the special hydraulic support 1 for filling are moved forward. At the same time, the transfer belt conveyor 15 behind the frame is moved forward accordingly. Under the cover of the cantilever plate structure formed by the roof and the special hydraulic support 1 for filling, steps e to i are repeated to gradually complete the extension of the gabion masonry wall and the "internal grouting + external spraying" combination reinforcement of the dry stone strip wall. The strip filling body 17 is gradually formed behind the hydraulic support 18, and the filling work of the goaf 16 is gradually completed. Figure 6 As shown;

[0082] k. After the slurry inside the strip filling body 17 solidifies, the hydraulic support 18 and the special hydraulic support 1 for filling are moved forward. After the overlying roof collapses periodically, it is observed that the compression of the strip filling body 17 in the collapsed area is too high, and the gabion masonry blocks on the surface of some strip filling bodies 17 slip and dislocate slightly. During the subsequent construction of the strip filling body 17, three groups of tension anchor rods 12 are arranged longitudinally during the stacking of the gabion masonry blocks 10 filled in step f. For every 1.5m extension of the strip filling body, one group of tension anchor rods 12 is arranged. The corresponding matching tension anchor rod tray 11 has a side length of 40cm, which strengthens the integrity of the neatly stacked gabion masonry block wall, limits the deformation of the formed strip filling body 17, and enhances the bearing capacity. The tension anchors were set to 10m in length (1.11 times the fill width a), with a reserve size for the anchor tray installation. This ensured the large anchor trays at both ends could effectively restrain the lateral deformation of the strip gangue, enhancing the integrity of the gabion gangue wall after grouting. The rectangular anchor trays were designed to have a side length similar to the height of the box-shaped gabion, ensuring they could restrain the slippage of the loaded gabion masonry blocks that the anchors directly contacted, thereby strengthening the integrity and load-bearing capacity of the strip gangue.

[0083] l, after the final filling mining is completed, the goaf is obtained as follows Figure 6The parallel strip filling bodies 17 shown have a wall width of 9m and are directly connected to the top, forming a regular underground space in the goaf separated by strip filling bodies, which occupies 65% to 75% of the volume of the entire mined space. Various types of carbon storage and negative carbon materials can be thrown and stacked in the formed underground space for comprehensive utilization, helping to achieve "zero carbon" mines.

Claims

1. A structural filling mining method combining stone masonry, grouting and spraying after gabion erection, characterized in that: The steps include: (1) According to the geological conditions of the working face, the thickness of the coal seam, the amount of gangue at the working face, the movement of the roof rock layer and the speed of the working face, the height h, width a, spacing b between the filling bodies and filling rate V of the goaf strip filling are determined; at the same time, a filling chamber is arranged underground, and the gangue produced after the underground sorting is piled in the filling chamber; (2) Design the length L1, width a1 and height h1 of the box-shaped gabion according to the parameters determined in step (1); determine the material, mesh size and wire diameter of the box-shaped gabion according to the strength, average particle size and shape of the sorted gangue; (3) With the completion of the construction of the coal seam transport tunnel, the return air tunnel and the opening of the cutting hole, the coal mining machine, the hydraulic support and the special hydraulic support for filling are transported to the working face for arrangement and erection. The hydraulic support at the position of the strip filling body designed in step (1) is the special hydraulic support for filling; (4) transporting the gabion mesh to the underground filling tunnel, processing it into a box-shaped gabion mesh of the size designed in step (2) underground, and loading the waste rock sorted underground into the gabion mesh and sealing it; (5) The gabion mesh filled with gangue is transported to the rear of the hydraulic support of the mining working face by a belt conveyor, and the gabion mesh masonry blocks are transported to the position of the filling special hydraulic support arranged in step (3) by the gabion mesh masonry block transfer belt conveyor arranged behind the hydraulic support; (6) Under the protection of the special hydraulic support for filling, the loaded gabion masonry blocks are lifted and stacked neatly by the lifting and stacking device of the special hydraulic support for filling to form a dry stone strip wall; (7) During the stacking process of the gabion masonry blocks filled in step (6), a grouting pipe is left at the center of the dry stone strip wall parallel to the coal mining working face. As the mining working face advances, the dry stone strip wall is stacked and extended while the grouting pipe is connected and extended; (8) Cement mortar is sprayed on both sides of the dry stone strip wall formed by stacking through the spraying pipe equipped with a special hydraulic support. The purpose is to form a thin cement mortar sealing layer on the surface of the dry stone strip wall. The cement mortar is sprayed into the surface of the dry stone strip wall and the pores of the surface broken gangue by compressed air, so as to consolidate the surface loose gangue into a whole and form a preliminary support on both sides of the dry stone strip wall. (9) After the sprayed cement mortar solidifies, grouting is performed into the interior of the dry stone strip wall formed by stacking the loaded gabion masonry blocks through the grouting pipe connected in step (7). The grouting liquid diffuses from the center to the outside and gradually fills the pores, thereby consolidating the dry stone strip wall into a whole. (10) When the coal cutter completes a round of coal cutting, the hydraulic support moves forward and the belt conveyor behind the support moves forward accordingly. Under the cover of the cantilever plate structure formed by the roof, steps (5) to (10) are repeated to gradually complete the extension of the gabion masonry wall and the "internal grouting + external spraying" combination reinforcement of the dry stone strip wall. A strip filling body is formed behind the hydraulic support, and the filling work of the goaf is gradually completed. (11) After the slurry inside the strip filling solidifies, several parallel strip fillings are formed in the goaf. After the overlying roof collapses periodically, timely attention should be paid to the compression and bearing capacity of the strip filling.

2. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 1, characterized in that: In step (1), the height of the strip filling body is determined comprehensively based on the gangue production of the working face and the height of the goaf, so as to ensure that all the gangue produced by the working face is utilized and the purpose of not lifting the gangue to the well is achieved; the height h of the strip filling body, the width a of the filling body, and the spacing b between the filling bodies are determined based on the height H of the goaf of the working face and the width A of the working face, that is, H=h, a / (a+b) =0.2~0.3; the filling rate V is determined based on the advancing speed of the working face, and the filling rate is required to be consistent with the advancing speed of the working face.

3. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 2, characterized in that: According to the filling body width a and goaf height H determined in step (1), the length L1, width a1 and height h1 of the box-shaped gabion are determined. The goaf height H is equal to the goaf strip filling body height h. The goaf strip filling body height h / gabion height h1 is an integer. The filling body width a / gabion width a1 is an integer. According to the determined gabion height h1 and gabion width a1, the length L1 of the gabion is determined. The gabion length L1: width a1: height h1=4:2:1 is required to ensure the feasibility of staggered stacking during the stacking of the filled gabion masonry blocks.

4. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 1, characterized in that: The filling-specific hydraulic support includes a hydraulic support body, a lifting and stacking device, a grouting device and a baffle. The support top beam is extended backward on the basis of the hydraulic support body to protect the transportation of gabion masonry blocks during on-site construction; a lifting and stacking device, a grouting device and a support baffle are arranged behind the hydraulic support body, and the lifting and stacking device moves along the filling direction through the lifting and stacking device slide rail arranged under the support top beam; the grouting device includes a shotcrete pipe and a shotcrete pipe slide rail; a support baffle is provided in the vertical direction behind the hydraulic support body, a shotcrete pipe slide rail is provided on the support baffle in the vertical direction, and a shotcrete pipe is provided in the vertical direction along the shotcrete pipe slide rail; the shotcrete pipe is arranged in the horizontal direction.

5. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 1, characterized in that: The size of the box-shaped gabion is determined according to the size and shape of the gangue produced by underground sorting, ensuring that the size of the gangue filled in the box-shaped gabion is greater than 1.5 times the mesh size; after the box-shaped gabion is processed into the designed size, it is lined with a layer of densely woven nylon mesh before filling the gangue underground; the gabion is selected from one of low-carbon steel wire, lead wire gabion, plastic-coated gabion, and galvanized gabion.

6. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 1, characterized in that: Step (4) During the filling process, the gabion mesh is vibrated to ensure that the internal gangue filler is fully in contact; it is required that the internal void ratio of the gangue filler is less than 35% after it is fully filled and sealed.

7. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after gabion support according to claim 1 is characterized in that: One or more grouting pipes are arranged inside the dry stone strip wall. The grouting pipes are designed to be connectable short pipes and are connected and extended according to the length of the working surface. During the spraying process, the box-shaped gabion mesh and the nylon mesh lining act as hanging nets to ensure the adhesion effect of the surface slurry during the spraying process.

8. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after the gabion is erected according to claim 7, characterized in that: The aggregate in the cement mortar during the spraying process is gangue fragments and powder with a particle diameter of less than 1 cm in underground gangue, the slurry mass ratio in the cement mortar is: cement: aggregate: water = 1~1.2: 3~3.5: 0.5~0.6, the dosage of the accelerator is 3%~5% of the total slurry mass; and the working wind pressure during the spraying process is greater than 0.5MPa, and the spraying thickness is greater than 40mm.

9. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after gabion support according to claim 1 is characterized in that: During the stacking process of the filled gabion masonry blocks, tension anchors are arranged at intervals of 2m to 10m along the length of the filling body. The trays at both ends of the tension anchors constrain the deformation of the strip filling body in the width direction, while increasing the area of the anchor trays on both sides of the wall to enhance the bearing capacity.

10. The structural filling mining method of the combined stone masonry-grouting-shotcreting method after gabion support according to claim 9, characterized in that: The length of the tension anchor rods set inside the wall is matched with the width a of the filling body. The length of the tension anchor rods is 1.05 to 1.15 times the width a of the filling body. The installation size of the anchor rod tray is reserved to ensure that the lateral deformation of the strip gangue can be effectively restrained under the constraint of the large-area anchor rod trays at both ends, thereby enhancing the integrity of the gabion gangue wall after grouting.

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