Structure filling mining method combining stone laying, grouting and guniting of gabion net behind frame

Abstract

The invention discloses a rear-frame gabion net stone laying-grouting-guniting combined structure filling mining method, and belongs to the technical field of coal mining. According to the method, bulk gangues generated on a working face are processed into standardized box-shaped gabion net gangue masonry bodies, the box-shaped gabion net gangue masonry bodies are stacked and built into the dry stone strip wall through a lifting stacking device of a filling special hydraulic support, and meanwhile the dry stone strip wall is solidified into a whole through a combined reinforcing method of external guniting and internal grouting. And a plurality of parallel strip type filling wall bodies are formed behind the working face. The continuous mining and continuous filling mining method is high in mechanization and integration degree, in the working face advancing process, gangue does not ascend to a well and is recycled, the filling mode is partial filling, and the two technical problems of high filling cost and gangue solid waste pollution under the environment-friendly mine background can be solved at the same time; various kinds of carbon storage and negative carbon materials can be thrown and stacked in the formed underground space for comprehensive utilization, implementation of a zero-carbon mine is assisted, and secondary utilization of a goaf is achieved.

Description

Technical Field

[0001] The invention relates to a method for structural backfilling mining in a continuous mining and backfilling coal mine, specifically to a combined structural backfilling mining method of building stone cages and masonry - grouting - shotcreting behind the support, belonging to the technical field of coal mining. Background Art

[0002] Under the goal of "dual carbon", the construction of green mines has put forward higher requirements for the filling of gangue solid waste and surface subsidence in underground coal mining. In this context, gangue filling mining has gradually become an effective path for the construction of green mines. The existing full - mining and full - backfilling methods have good effects in controlling overlying rock deformation and surface subsidence. However, methods such as paste filling require a large amount of cement and other cementitious materials, resulting in high costs, which severely restricts the large - scale application of filling mining. In addition, the proportion of solid waste generated by coal mines themselves is small. The amount of coal gangue generated is only 15% - 20% of the coal mining volume, and the amount of power plant fly ash generated is only 20% - 30% of the coal combustion volume. 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, it is difficult to ensure the filling effect. In this context, some researchers have proposed the idea of structural backfilling (Feng Guorui, Du Xianjie, Guo Yuxia, et al. Basic theory of structural backfilling 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 too high natural strength index requirements during the full - filling process. According to the distribution of coal seams and the characteristics of their surrounding rocks, structural backfilling arranges column (pier) - shaped, strip (wall) - shaped or box - shaped structural backfill bodies at key positions in the goaf through pre - mining planning and solid waste resource utilization, so as to achieve the goal of controlling rock strata movement and surface subsidence. Structural backfilling provides a new technical idea for the efficient utilization of 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 process of mining technology, the fully - mechanized caving mining technology and equipment for thick coal seams have become increasingly mature and perfect. However, the development of mechanized equipment dedicated to backfilling is slow. And most of the existing local backfilling mining methods require additional construction of partition walls, wasting manpower, material resources, with high costs and low efficiency, which will also affect the backfilling effect. Especially, the mechanized "continuous mining and backfilling" technical system related to structural backfilling needs to be further improved and developed. At present, ensuring the backfilling effect while not lifting gangue out of the well during the mining process and achieving efficient support for the roof rock strata of the goaf have become the premise of mining design. Therefore, it is extremely urgent to propose a high - cost - performance and high - mechanization "continuous mining and backfilling" technical system based on gangue solid waste. Summary of the Invention

[0004] The present invention aims to provide a combined structural filling mining method of post - support gabion mesh masonry - grouting - shotcreting. Guided by structural filling, using the gangue generated at the working face as the main aggregate, loose coal gangue is filled into a designed box - type gabion mesh box and sealed. Then, the filled gabion meshes are stacked and masoned to form a dry - masonry strip wall. At the same time, through the combined reinforcement method of "external shotcreting + internal grouting", the loose gangue in the dry - masonry strip wall is solidified into a whole, forming several parallel strip filling bodies behind the working face. While ensuring that the gangue does not go to the surface, the filling effect is guaranteed, and thus efficient support for the roof strata of the goaf is achieved.

[0005] The present invention provides a combined structural filling mining method of post - support gabion mesh masonry - grouting - shotcreting, which specifically includes the following steps: (1) According to the geological conditions of the working face, coal seam thickness, gangue volume at the working face, roof strata migration situation, and working face advancing speed, determine the filling body height h, filling body width a, spacing b between filling bodies, and filling rate V of strip filling in the goaf. At the same time, arrange filling chambers underground and stack the coal gangue generated after underground separation in the filling chambers.

[0006] (2) Design the length L1, width a1, and height h1 of the box - shaped gabion mesh according to the parameters determined in step (1). Determine the material of the box - shaped gabion mesh, as well as the mesh size and wire diameter specifications according to the strength, average particle size, and shape of the separated gangue.

[0007] Preferably, the width h1 of the box - shaped gabion mesh = H / n (n is an integer to ensure that the strip filling body is fully in contact with the roof after masonry), and h1 = 0.5 * a1 = 0.25 * L1.

[0008] (3) With the completion of the construction of the coal seam haulage roadway, return airway, and open - off cut, the shearer, hydraulic supports, and special hydraulic supports for filling are transported into the working face for layout and erection. Among them, the hydraulic supports at the positions of the strip filling bodies designed in step (1) are special hydraulic supports for filling. When the width of the filling body is greater than the width of a single 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 set.

[0009] (4) Transport the gabion mesh to the underground filling roadway, process it into a box - shaped gabion mesh with the dimensions designed in step (2) underground, and load the gangue separated underground into the gabion mesh and seal it.

[0010] (5) The gabion net filled with gangue is transported to the rear of the hydraulic support at the mining face by a belt conveyor, and the filled gabion net masonry block is transported to the position of the special hydraulic support for filling arranged in step (3) by the gabion net masonry block transfer belt conveyor arranged at the rear of the hydraulic support. The special hydraulic support for filling moves while mining, and the mined space is filled with building blocks.

[0011] (6) Under the cover of the special hydraulic support for filling, the filled gabion net masonry block is lifted and stacked neatly by the lifting and stacking device of the special hydraulic support for filling to form a dry-laid stone strip wall.

[0012] (7) During the stacking process of the gabion net masonry block filled in step (6), a grouting pipe is reserved at the central position parallel to the coal mining face of the dry-laid stone strip wall. As the mining face advances, the dry-laid stone strip wall is extended while the grouting pipe is connected and extended. Generally, the working face is hundreds of meters long, so the grouting pipe is designed as a connectable short pipe and extended according to the length of the working face.

[0013] (8) The mortar is sprayed on both sides of the dry-laid stone strip wall formed by stacking through the spraying pipe equipped with the special hydraulic support for filling. The purpose is to form a thin mortar sealing layer on the surface of the dry-laid stone strip wall. At the same time, the mortar is sprayed onto the surface of the dry-laid stone strip wall and the pores of the surface broken gangue by using compressed air to solidify the surface loose gangue into a whole, and a preliminary support is formed on both sides of the dry-laid stone strip wall.

[0014] (9) After the sprayed mortar solidifies, grouting is carried out into the dry-laid stone strip wall formed by stacking the filled gabion net masonry block through the grouting pipe connected in step (7). The slurry diffuses from the center to the outside and gradually fills the pores to solidify the dry-laid stone strip wall into a whole. The mortar sealing layer formed by spraying on both sides of the dry-laid stone strip wall ensures the tightness 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-laid stone strip wall and the roof to ensure the roof contact effect of the masonry strip wall.

[0015] (10) After the coal cutting machine completes one round of coal cutting work, while the hydraulic support moves forward, the transfer belt conveyor behind the support moves forward accordingly. Under the cover of the cantilever plate structure formed on the roof, steps (5) to (10) are repeated to gradually complete the extension of the gabion net masonry wall, and at the same time complete the combined reinforcement of "internal grouting + external spraying" of the dry-laid stone strip wall, form a strip filling body behind the hydraulic support, and gradually complete the goaf filling work.

[0016] (11) After the slurry inside the strip filling body solidifies, several parallel strip filling bodies are formed in the goaf. After the overlying roof periodically collapses, pay attention to the compression amount and bearing capacity of the strip filling body in a timely manner.

[0017] When the compression amount of the filling body in the roof caving area is too high and the bearing capacity is insufficient, during the subsequent construction process of the strip filling body, during the stacking process of the gabion mesh masonry blocks filled with materials, along the length direction of the filling body, tension bolts are arranged at intervals of 2 m to 10 m; specifically, tension bolts are arranged in the middle of the gabion mesh masonry blocks, that is, in the width direction of the dry-laid stone strip wall, penetrating the entire wall body, and the deformation of the strip filling body in the width direction is restricted by the trays at both ends of the tension bolts (the trays are arranged on the side of the wall), and at the same time, the area of the bolt 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.

[0018] In the above method, the special filling hydraulic support includes a hydraulic support main body, a lifting and stacking device, a grouting device and a baffle. The support roof beam extends backward on the basis of the hydraulic support main body to cover the transportation of the gabion mesh masonry blocks during the on-site construction process; a lifting and stacking device, a grouting device and a support baffle are arranged behind the hydraulic support main body. The lifting and stacking device moves along the filling direction through the lifting and stacking device slide rail arranged under the support roof beam; the grouting device includes a spraying pipe and a spraying pipe slide rail; a support baffle is arranged in the vertical direction behind the hydraulic support main body, a spraying pipe slide rail is arranged on the support baffle in the vertical direction, and a spraying pipe is arranged in the direction perpendicular to the spraying pipe slide rail; the spraying pipe is arranged in the horizontal direction.

[0019] In the above method, after the box-shaped gabion mesh is processed into the designed size, before filling gangue underground, a layer of tightly woven nylon mesh is lined inside to ensure that small-sized particles generated by the bite and friction of the internal loose gangue leak out of the gabion mesh.

[0020] In the above method, in step (1), the height of the strip filling body is comprehensively determined according to the gangue output of the working face and the height of the goaf, so as to ensure that all the gangue generated by the working face is utilized and the purpose of not lifting the gangue out of the well is achieved.

[0021] Specifically, based on the coal gangue production being 15% - 20% of the coal mining volume, the gangue volume of the working face is estimated through the coal output of the working face; the volume of the gangue in the working face is deduced with a bulking coefficient of 1.5. According to the height H of the goaf of the working face and the width A of the working face, the filling body height h, the filling body width a, and the spacing b between the filling bodies of the goaf strip filling are determined, that is, H = h, a / (a + b) = 0.2 - 0.3; the filling rate V is determined according to the advancing speed of the working face, and it is required that the filling rate is consistent with the advancing speed of the working face.

[0022] In the above method, in step (2), the size of the box-shaped gabion mesh 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 mesh 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.

[0023] 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, 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.

[0024] In the above method, in step (2), the bearing capacity requirement of the gangue strip wall is determined according to the strength of the underground sorted gangue and the migration of the overlying rock strata, and the type of gabion mesh and the wire diameter specification of the gabion mesh are adjusted in combination with the strength of the single gabion mesh gangue block after grouting determined by laboratory tests. The type of gabion mesh can be selected from low-carbon steel wire, lead wire gabion mesh, plastic-coated gabion mesh, galvanized gabion mesh, etc. When there is a high demand for the strength of the strip filling body, reinforced gabion mesh is selected.

[0025] 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 internal gangue filler is fully in contact. It is required that after the gangue filler is filled and sealed, the internal void ratio is less than 35%, so as to avoid excessive slurry demand in the subsequent grouting process, ensure the bearing performance of the strip filling body and improve 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 strengthened by the bite and friction between the loose gangue blocks.

[0026] In the above method, during the bulk gangue filling process in step (4), large pieces of gangue 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 treatment.

[0027] In the above method, the length of the grouting pipeline in step (7) is comprehensively determined based on the advancement speed of the working face, the top control distance and the initial setting time of the grouting material, so as to ensure that as the working face advances, the grouting work is completed and the slurry is solidified and has the bearing capacity before the periodic collapse of the overlying roof. 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 leakage or insufficient slurry diffusion along the direction of the strip filling body. 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 leak from the stacked masonry blocks.

[0028] 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 parallel to the dry stone strip wall and the working surface direction.

[0029] In the above method, the aggregate in the cement mortar during the spraying process is gangue debris 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, and the dosage of the accelerator is 3%~5% of the total slurry mass. In addition, the working wind pressure during the spraying process is greater than 0.5MPa, and the spraying thickness is greater than 40mm.

[0030] In the above method, the box-shaped gabion mesh and the inner lining nylon mesh can act as hanging meshes during the spraying process to ensure the adhesion of the surface slurry during the spraying process. After spraying, the loose gangue within 3cm of the surface depth of the dry stone strip wall solidifies into a whole, and the rock blocks are well bitten and inlaid. Together with the cement mortar layer after the surface of the wall solidifies, it acts as a "template" on the side surface of the wall, providing a closed space for the internal grouting construction, and avoiding slurry running along both sides of the wall during the spraying construction.

[0031] 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 on the working face is estimated by using 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, a regular underground space is formed in the goaf, which is separated by strip filling bodies and accounts for 65% to 75% of the volume of the entire mined space. Various types of carbon storage and negative carbon materials can be thrown and piled in the formed underground space for utilization, thereby helping to achieve a "zero carbon" mine.

[0032] In the above method, the length of the tie bolts left inside the wall in step (11) matches the width a of the filling body designed in step (1). Generally, the length of the tie bolts is set to be 1.05 to 1.15 times the width a of the filling body, reserving the installation dimension for the bolt trays, ensuring that the lateral deformation of the strip gangue can be effectively constrained under the restraint of large-area bolt trays at both ends, and enhancing the integrity of the gabion wall after grouting. The side length of the designed rectangular bolt tray is similar to the height of the box-shaped gabion net, ensuring that the rectangular bolt tray can restrain the slip and dislocation of the filled gabion masonry blocks directly contacted by the bolts, and strengthening the integrity and load-bearing performance of the strip filling body.

[0033] Advantages of the present invention: (1) The present invention processes the bulk gangue generated at the working face into standardized box-shaped gabion wall masonry blocks, giving full play to the strengthening function of the biting friction force between irregular bulk gangue blocks on the load-bearing capacity of the strip filling body. The dry-laid stone strip wall is stacked and built by the lifting and stacking device of the special hydraulic support for filling. At the same time, the dry-laid stone strip wall is solidified into a whole by the combined reinforcement method of "external shotcreting + internal grouting", forming several parallel strip-shaped filling walls behind the working face.

[0034] (2) The present invention proposes a continuous mining and continuous filling mining method with a high degree of mechanization and integration. During the advancement of the working face, the gangue does not go to the surface and is recycled. The construction process is reasonably connected, effectively saving manpower and material resources and simplifying the construction method. Moreover, the filling work closely follows the mining working face, and the two advance synergistically, filling the entire cross-section at one time, strictly controlling the settlement of the overlying strata, and effectively controlling the surface subsidence.

[0035] (3) The present invention realizes the non-surface lifting of gangue + continuous mining and continuous filling during the coal mining process, which can significantly save the costs of lifting and discharging gangue to the surface. The filling method is partial filling, and the main coarse aggregate for filling is underground gangue and the caving immediate 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 gangue solid waste pollution under the background of green mines.

[0036] (4) For coal seams with good strata conditions, the gob area after filling can obtain a neat underground space divided by the strip filling body, where various carbon storage and negative carbon materials can be thrown and stacked for comprehensive utilization, contributing to the realization of a "zero-carbon" mine and secondary utilization of the gob area. Description of the drawings

[0037] Figure 1 is a schematic diagram of the special hydraulic support for filling used in the present invention; Figure 2 is a schematic diagram of the raw materials and processing process of the gabion masonry blocks; Figure 3Schematic diagram of the implementation process of the combined structure filling mining method of post-frame gabion masonry - grouting - shotcreting; Figure 4 Schematic cross-section of the completed strip filling body parallel to the coal mining face; Figure 5 Schematic cross-section of the dry masonry wall under construction parallel to the coal mining face; Figure 6 Schematic layout of the filling mining face during the advancing process; In the figure: 1 - Special hydraulic support for filling, 2 - Lifting and palletizing device, 3 - Slide rail of the lifting and palletizing device, 4 - Shotcreting pipe, 5 - Slide rail of the shotcreting pipe, 6 - Support baffle, 7 - Bulk gangue, 8 - Box-shaped gabion mesh, 9 - Box-shaped gabion mesh lined with nylon mesh, 10 - Gabion mesh masonry block filled, 11 - Pulling anchor tray, 12 - Pulling anchor, 13 - Shotcreting layer on the surface of the dry masonry wall, 14 - Grouting pipe, 15 - Transfer belt conveyor, 16 - Goaf, 17 - Strip filling body, 18 - Hydraulic support, 19 - Coal mining face. Detailed implementation method

[0038] The following embodiments are intended to illustrate and explain the present invention schematically and do not limit the scope of the present invention.

[0039] For a clearer understanding of the technical objectives, features, and effects of the present invention, the method for freezing and ascending mining of the empty coal seam between coal pillars in the goaf is further described in detail below with reference to the accompanying drawings.

[0040] This embodiment provides a combined structure filling mining method of post-frame gabion masonry - grouting - shotcreting, which specifically includes the following steps: (1) According to the geological conditions of the working face, coal seam thickness, amount of gangue in the working face, movement of roof rock strata, and advancing speed of the working face, determine the height h, width a, spacing b between the filling bodies, and filling rate V of the strip filling in the goaf; at the same time, arrange a filling chamber underground and stack the coal gangue generated after underground sorting in the filling chamber.

[0041] (2) Design the length L1, width a1, and height h1 of the box-shaped gabion mesh according to the parameters determined in step (1); determine the material of the box-shaped gabion mesh, as well as the mesh size and wire diameter specifications according to the strength, average particle size, and shape of the sorted gangue.

[0042] Preferably, the width h1 of the box-shaped gabion mesh = H / n (n is an integer to ensure that the strip filling body is fully in contact with the roof after masonry), and h1 = 0.5 * a1 = 0.25 * L1.

[0043] (3) With the completion of the construction of the coal seam haulage roadway, return airway, and cutting roadway, the shearer, hydraulic supports, and special hydraulic supports for backfilling are transported into the working face for layout and erection. Among them, the hydraulic supports at the positions of the strip backfill bodies designed in step (1) are special hydraulic supports for backfilling. When the width of the backfill body is greater than the width of the special hydraulic support for backfilling, multiple special hydraulic supports for backfilling are arranged in parallel. When the width of the backfill body is less than the width of a single special hydraulic support for backfilling, one special hydraulic support for backfilling is set.

[0044] (4) Transport the gabion mesh to the underground backfilling roadway, process it into the box-shaped gabion mesh with the designed dimensions in step (2) underground, and load the gangue sorted underground into the gabion mesh and seal it.

[0045] (5) Transport the gabion mesh filled with gangue to the rear of the hydraulic supports in the mining face through a belt conveyor, and transport the filled gabion mesh masonry blocks to the positions of the special hydraulic supports for backfilling arranged in step (3) through the gabion mesh masonry block transfer belt conveyor arranged behind the hydraulic supports; The special hydraulic supports for backfilling move while mining, and the mined space is filled with building blocks.

[0046] (6) Under the cover of the special hydraulic supports for backfilling, lift and stack the filled gabion mesh masonry blocks neatly through the lifting and stacking device of the special hydraulic supports for backfilling to form a dry-laid stone strip wall.

[0047] (7) During the stacking process of the gabion mesh masonry blocks filled in step (6), leave a grouting pipe at the central position parallel to the coal mining face of the dry-laid stone strip wall. As the mining face advances, the dry-laid stone strip wall is extended while the grouting pipe is connected and extended. Generally, the working face is hundreds of meters long, so the grouting pipe is designed as a connectable short pipe and is connected and extended according to the length of the working face.

[0048] (8) Spray cement mortar on both sides of the dry-laid stone strip wall formed by stacking through the spray pipe equipped with the special hydraulic supports for backfilling. The purpose is to form a thin cement mortar sealing layer on the surface of the dry-laid stone strip wall. At the same time, use compressed air to spray the cement mortar into the pores of the surface of the dry-laid stone strip wall and the surface broken gangue to solidify the surface loose gangue into a whole, and form a preliminary support on both sides of the dry-laid stone strip wall.

[0049] After the sprayed cement mortar solidifies, grouting is carried out into the dry-stone strip wall formed by stacking and piling the filled gabion mesh masonry blocks through the grouting pipe connected in step (7). The grout diffuses from the center to the outside and gradually fills the pores, solidifying 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, avoiding problems such as grout leakage. At the same time, the grout can diffuse into the gap between the top of the dry-stone strip wall and the roof, ensuring the top connection effect of the stone strip wall.

[0050] (10)After the coal cutting machine completes one round of coal cutting work, while the hydraulic support moves forward, the transfer belt conveyor behind the support also moves forward accordingly. Under the cover of the cantilever plate structure formed on the roof, steps (5) to (10) are repeated to gradually complete the extension of the gabion mesh masonry wall, and at the same time complete the combined reinforcement of "internal grouting + external spraying" for the dry-stone strip wall, forming a strip filling body behind the hydraulic support and gradually completing the gob filling work.

[0051] (11)After the grout inside the strip filling body solidifies, several parallel strip filling bodies are formed in the gob. After the overlying roof collapses periodically, pay attention to the compression amount and bearing capacity of the strip filling body in a timely manner.

[0052] When the compression amount of the filling body in the roof collapse area is too high and the bearing capacity is insufficient, during the subsequent construction of the strip filling body, during the stacking process of the filled gabion mesh masonry blocks, tension bolts are arranged at intervals of 2m to 10m along the length direction of the filling body; specifically, tension bolts are set in the middle of the gabion mesh masonry blocks, that is, in the width direction of the dry-stone strip wall, penetrating the entire wall, and the compression deformation of the strip filling body is restricted by the trays at both ends of the tension bolts (the trays are arranged on the side of the wall), and at the same time, the area of the bolt 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.

[0053] In the above method, after the box-shaped gabion mesh is processed into the designed size, before filling gangue underground, a layer of tightly woven nylon mesh is lined inside to ensure that small-sized particles generated by the biting friction of the internal loose gangue leak out of the gabion mesh.

[0054] In the above method, in step (1), the height of the strip filling body is comprehensively determined according to the gangue output of the working face and the height of the goaf, ensuring that all the gangue generated at the working face is utilized and the purpose of not lifting the gangue out of the shaft is achieved. Specifically, based on the coal gangue production being 15% - 20% of the coal mining volume, the gangue volume at the working face is estimated through the coal output at the working face; the volume of the gangue at the working face is deduced with a bulking coefficient of 1.5. According to the height H of the goaf at the working face and the width A of the working face, the height h, width a, and spacing b between the filling bodies of the goaf strip filling are determined, that is, H = h, a / (a + b) = 0.2 - 0.3; the filling rate V is determined according to the advancing speed of the working face, and it is required that the filling rate is consistent with the advancing speed of the working face.

[0055] In the above method, in step (2), the size of the box-shaped gabion net 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 net is more than 1.5 times the mesh size; during the mechanical filling process, the proportion of the bulk gangue of each size should be sieved and controlled to ensure good gradation of the aggregate, and the filled gangue shall not leak out or exceed the net body.

[0056] In the above method, according to the filling body width a and the goaf height H determined in step (1), the length L1, width a1, and height h1 of the box-shaped gabion net are determined, with the requirements: the goaf height H is equal to the height h of the goaf strip filling body, and the ratio of the height h of the goaf strip filling body to the height h1 of the gabion net is an integer; the ratio of the filling body width a to the gabion net width a1 is an integer; according to the determined gabion net height h1 and gabion net width a1, the length L1 of the gabion net is determined, and it is required that the length L1: width a1: height h1 of the gabion net = 4:2:1 to ensure the feasibility of staggered stacking during the stacking process of the filled gabion net masonry blocks.

[0057] In the above method, in step (2), the bearing capacity requirements of the gangue strip wall are determined according to the strength of the underground sorted gangue and the movement of the overlying strata, and combined with the strength of a single gabion net gangue block after grouting determined by laboratory tests, the type and wire diameter specification of the gabion net are adjusted. The type of gabion net can be selected from low-carbon steel wire, lead wire gabion net, plastic-coated gabion net, galvanized gabion net, etc. When there is a high demand for the strength of the strip filling body, a reinforced gabion net is selected.

[0058] In the above method, the length of the grouting pipeline in step (7) is comprehensively determined according to the advancing speed of the working face, the roof control distance, and the initial setting time of the grouting material, so as to ensure that the grouting work is completed before the periodic caving of the overlying roof and the slurry solidifies and has the bearing capacity as the working face advances. At the same time, it is required that the safety distance between the grouting area and the area where dry-laid stone strips are being stacked and piled matches the grouting pressure to avoid slurry leakage along the direction of the strip filling body or insufficient slurry diffusion; specifically, when the safety distance between the grouting area and the area where dry-laid stone strips are being stacked and piled is too long, the space to be grouted is too large, and the grouting pressure is too small, it will cause the slurry to be difficult to diffuse into every pore; when the safety distance is too short, the space to be grouted is too small at this time, and the grouting slurry will leak from the stacked masonry blocks. In the above method, when the grouting efficiency of a grouting pipe arranged inside the dry-laid stone strip wall does not match the advancing efficiency of the working face, or the slurry cannot completely diffuse to the dead corner of the designed grouting area, the number of grouting pipes should be increased, that is, multiple grouting pipes are evenly arranged along the center line parallel to the direction of the dry-laid stone strip wall and the working face.

[0059] In the above method, combined with the existing mining experience, the amount of coal gangue generated is 15% - 20% of the coal mining volume. Calculating the volume of gangue in the working face based on the swelling coefficient of 1.5, it is estimated that the volume of the strip filling body formed after grouting in step (9) and shotcreting in step (8) accounts for 25% - 35% of the entire goaf volume, that is, the filling rate of the goaf after continuous mining and filling using this method is 25% - 35%. At the same time, a regular underground space accounting for 65% - 75% of the entire mined-out space volume is formed in the goaf with strip filling bodies spaced apart, and various carbon storage and negative carbon materials can be thrown and stacked in the formed underground space for utilization to help achieve a "zero-carbon" mine.

[0060] The average thickness of the 8# coal seam in a certain mine is 5.25m. In response to the requirements of the green mine construction goal of the competent department, it is required to effectively control the surface subsidence and scientifically handle problems such as the gangue yard. After scientific demonstration in the mining area, it is expected to carry out filling mining in the 18403 working face and make full use of the gangue generated in the working face. The average advancing rate of the adjacent working face of the 8# coal seam is 4m / d, and the output of sorted coal gangue is about 15% of the coal resource output. In view of the above situation, the implementation process of the present invention will be further described in detail below with reference to the accompanying drawings. The specific implementation steps are as follows: a. Based on the hydrogeological conditions and coal seam thickness of the 18403 working face, combined with the amount of gangue in adjacent working faces of the already mined No. 8 coal seam, the movement of roof strata, and the advancing speed of the working face, the height h of the strip filling body 17 is determined to be 5.25 m, the width a of the filling body is 9 m, the spacing b between strip filling bodies is 30 m, and the filling rate is consistent with the advancing rate of the working face, V = 4 m / d. Ensure that all the gangue generated in the working face is utilized to achieve the goal of not lifting gangue out of the well. During the advancement of the working face, coal and gangue separation is carried out underground, and at the same time, the gangue generated by separation is transported to the filling chamber arranged underground; b. According to the width and filling rate of the strip filling body 17 in step a, the length L1 of the gabion mesh is determined to be 1.5 m, the width a1 is 0.75 m, and the height h1 is 0.375 m. The stacking quantity of the strip filling body in the vertical height is determined to be 14 pieces, ensuring the feasibility of staggered stacking during the formation of the strip wall by piling up gabion mesh masonry. According to the strength, average particle size, and shape of the gangue after separation, the material of the hexagonal gabion mesh (with hexagonal mesh holes) is determined to be galvanized steel wire, the wire diameter of the gabion mesh is 4.0 mm, and the side length of the mesh hole of the hexagonal gabion mesh is 0.12 m. The processed gabion mesh is internally lined with a tightly woven nylon mesh cushion to prevent the internal gangue from leaking out or exceeding the mesh body, and at the same time, it acts as a hanging mesh during the shotcreting process of the gangue strip wall after piling up; c. With the completion of the construction of the coal transportation roadway, return airway, and open-off cut, the shearer, conventional hydraulic supports 18, and special filling hydraulic supports 1 are transported into the working face for layout and erection. Among them, the support at the position of the strip filling body 17 designed in step a is the special filling hydraulic support 1, as Figure 1 shown. The special filling hydraulic support 1 includes a hydraulic support main body, a lifting and stacking device 2, a grouting device, and a support baffle 6. The support top beam extends backward on the basis of the hydraulic support main body to cover the transportation of gabion mesh masonry blocks during on-site construction; a lifting and stacking device 2, a grouting device, and a support baffle 6 are arranged behind the hydraulic support main body. The lifting and stacking device 2 moves along the filling direction through the lifting and stacking device slide rail 3 arranged under the support top beam; the grouting device includes a shotcrete pipe 4 and a shotcrete pipe slide rail 5; a support baffle 6 is arranged vertically behind the hydraulic support main body, and a shotcrete pipe slide rail 5 is arranged vertically on the support baffle 6, and a shotcrete pipe 4 is arranged in the direction perpendicular to the shotcrete pipe slide rail 5; the shotcrete pipe 4 is arranged horizontally; d. On the ground, the gabion mesh is processed into a box-shaped gabion mesh 8 with the dimensions designed in step b, transported to the underground filling chamber, lined with a tightly woven nylon mesh inside the box-shaped gabion mesh 8 transported to the underground, processed into a box-shaped gabion mesh 9 lined with nylon mesh, and the bulk gangue 7 generated after separation underground is loaded into the box-shaped gabion mesh 9 lined with nylon mesh by mechanical equipment and sealed to obtain the filled gabion mesh masonry block 10, as Figure 2As shown in the figure. During the filling process, the gabion mesh is vibrated to ensure the compactness of the internal gangue filler, guarantee the full contact of the internal gangue filler, give full play to the friction and interlocking properties between the bulk gangue blocks, control the internal void ratio to be less than 35%, avoid excessive slurry demand during the subsequent grouting process, and ensure the bearing capacity of the strip filling body while improving its economy as much as possible. Since the gangue is mostly polygonal crushed stones, it can fit well with each other in the box-shaped gabion mesh, and the bearing capacity of the filling body is strengthened through the occlusion and friction between the bulk gangue blocks; e. The filled gabion mesh masonry block 10 is transported to the coal mining face 19 through a belt conveyor, and through the transfer belt conveyor 15 arranged behind the hydraulic support 18, the filled gabion mesh masonry block 10 is transported to the position of the special filling hydraulic support 1 arranged in step c; f. Under the cover of the special filling hydraulic support 1, through the lifting and stacking device 2 and the lifting and stacking device slide rail 3 of the special filling hydraulic support 1, the filled gabion mesh masonry block 10 is lifted and stacked to form a dry-laid stone strip wall, as Figure 3 shown in the figure. During transportation, the special filling hydraulic support baffle 6 can effectively prevent the offset and sliding of the filled gabion mesh masonry block 10. During the transportation of the filled gabion mesh masonry block 10 to the goaf 16 through the transfer belt conveyor 15, the large gangue blocks that are too large to be loaded into the box-shaped gabion mesh are transported to the goaf 16 synchronously and thrown into the voids between the strip filling bodies 17 in the goaf 16 for treatment; g. During the stacking process of the filled gabion mesh masonry block 10 in step f, six grouting pipes 4 are reserved at the middle position of the cross-section of the stone wall parallel to the coal mining face. As the coal mining face 19 advances, the dry-laid stone strip wall is extended while the grouting pipes 4 are connected and extended; h. Through the spray pipe 4 and the spray pipe slide rail 5 equipped with the special filling hydraulic support 1, cement mortar is sprayed on both sides of the dry-laid stone strip wall formed by stacking in step f to solidify the masonry bulk on the surface of the dry-laid stone strip wall into a whole, and a preliminary support is formed on both sides of the dry-laid stone strip wall. During the spraying process, the gabion mesh and the inner nylon mesh can act as hanging meshes to strengthen the adhesion effect of the surface slurry during the spraying process. During the spraying process, the aggregate in the cement mortar is gangue debris and powder with a particle diameter less than 1 cm. The corresponding slurry mass ratio is: cement: aggregate: water = 1: 3: 0.6, and the dosage of the accelerating agent is 5% of the total mass. During the spraying process, the working wind pressure is greater than 0.5 MPa, and the average spraying thickness is 50 mm; i. After the sprayed cement mortar solidifies, the gangue within 3 cm of the surface depth of the dry-laid stone strip wall solidifies into a whole. Together with the shotcrete layer 13 on the surface of the dry-laid stone wall, it provides a sealed space for the internal grouting construction, acting as a "grouting formwork" on both sides of the dry-laid stone wall, avoiding slurry leakage along both sides of the wall during the grouting construction, and at the same time ensuring the roof connection effect of the stone strip wall. Grout is injected into the interior of the dry-laid stone strip wall formed by stacking through the grouting pipe 4 connected in step g to solidify the dry-laid stone strip wall into a whole, as Figure 4 and Figure 5 shown. Ensure that the slurry solidifies and has bearing capacity before the periodic caving of the roof; j. After the coal cutter completes one round of coal cutting work, while the hydraulic support 18 and the special hydraulic support 1 for backfilling move forward, the belt conveyor 15 behind the support moves forward accordingly. Under the cantilever plate structure formed by the roof and the cover of the special hydraulic support 1 for backfilling, repeat steps e to i to gradually complete the extension of the gabion masonry wall, and at the same time complete the combined reinforcement of "internal grouting + external shotcreting" of the dry-laid stone strip wall, gradually form a strip filling body 17 behind the hydraulic support 18, and gradually complete the filling work of the goaf 16, as Figure 6 shown; k. After the slurry inside the strip filling body 17 solidifies, the hydraulic support 18 and the special hydraulic support 1 for backfilling move forward. After the periodic caving of the overlying roof, it is observed that the compression of the strip filling body 17 in the caving area of the roof is too high, and some of the gabion masonry blocks on the surface of the strip filling body 17 slide and displace slightly. During the subsequent construction of the strip filling body 17, three groups of tension bolts 12 are arranged longitudinally during the stacking process of the gabion masonry blocks 10 filled in step f. For every 1.5 m extension of the strip filling body, one group of tension bolts 12 is arranged. The corresponding supporting tension bolt tray 11 has a side length of 40 cm to strengthen the integrity of the neatly stacked gabion masonry wall, limit the deformation of the formed strip filling body 17, and enhance the bearing capacity. The length of the tension bolt is set to 10 m (1.11 times the width a of the filling body), reserving the installation dimension of the bolt tray to ensure that the lateral deformation of the strip gangue can be effectively restricted under the constraint of large-area bolt trays at both ends, and enhance the integrity of the gabion gangue wall after grouting. The side length of the designed rectangular bolt tray is similar to the height of the box-shaped gabion, ensuring that the rectangular bolt tray can restrict the sliding and displacement of the filled gabion masonry blocks directly in contact with the bolt, and strengthen the integrity and bearing performance of the strip filling body; l. After the final filling mining is completed, the strip filling bodies 17 parallel to each other as shown in Figure 6 are obtained in the goaf. The width of the wall is 9 m, directly contacting the roof, forming a regular underground space with strip filling bodies spaced in the goaf, accounting for 65% - 75% of the entire mined space volume. Various carbon storage and negative carbon materials can be thrown and stacked in the formed underground space for comprehensive utilization, contributing to the realization of a "zero-carbon" mine.

Claims

1. A structural filling mining method combining post - support gabion mesh masonry - grouting - shotcreting, characterized in that, It includes the following steps: (1) Determine the filling body height h, filling body width a, spacing b between filling bodies, and filling rate V of strip filling in the goaf according to the working face geological conditions, coal seam thickness, amount of gangue in the working face, roof strata migration situation, and working face advancing speed; meanwhile, arrange filling chambers underground and stack the coal gangue generated after underground separation in the filling chambers; (2) Design the length L1, width a1, and height h1 of the box-shaped gabion net according to the parameters determined in step (1); determine the material of the box-shaped gabion net, as well as the mesh size and wire diameter specifications according to the strength, average particle size, and shape of the gangue after separation; (3) After the construction of the coal transportation roadway, return airway, and open-off cut is completed, the shearer, hydraulic support, and special hydraulic support for filling are transported into the working face for arrangement and erection, where the hydraulic support at the position of the strip filling body designed in step (1) is the special hydraulic support for filling; (4) Transport the gabion net to the underground filling roadway, process it into a box-shaped gabion net with the size designed in step (2) underground, and load the gangue separated underground into the gabion net and seal it; (5) Transport the gabion net filled with gangue to the rear of the hydraulic support in the mining working face through a belt conveyor, and transport the gabion net masonry blocks filled with gangue to the position of the special hydraulic support for filling arranged in step (3) through the gabion net masonry block transfer belt conveyor arranged behind the hydraulic support; (6) Under the cover of the special hydraulic support for filling, lift and stack the gabion net masonry blocks filled with gangue neatly through 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 net masonry blocks filled in step (6), leave a grouting pipe at the central position parallel to the coal mining working face of the dry-stone strip wall. As the mining working face advances, the dry-stone strip wall is extended while the grouting pipe is connected and extended; (8) Spray cement mortar on both sides of the dry-stone strip wall formed by stacking through the spray pipe supporting the special hydraulic support for filling. The purpose is to form a thin cement mortar sealing layer on the surface of the dry-stone strip wall, use compressed air to spray the cement mortar into the pores of the surface of the dry-stone strip wall and the surface broken gangue, solidify 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, grout into the dry-stone strip wall formed by stacking the gabion net masonry blocks filled in step (7) through the grouting pipe connected in step (7). The slurry diffuses from the center to the outside and gradually fills the pores to solidify the dry-stone strip wall into a whole; (10) After the shearer completes a round of coal cutting work, while the hydraulic support moves forward, the transfer belt conveyor behind the support moves forward accordingly. Under the cover of the cantilever plate structure formed on the roof, repeat steps (5) to (10) to gradually complete the extension of the gabion net masonry wall, and at the same time complete the combined reinforcement of "internal grouting + external spraying" of the dry-stone strip wall, form a strip filling body behind the hydraulic support, and gradually complete the goaf filling work; After the slurry inside the strip filling body solidifies, several parallel strip filling bodies are formed in the goaf. After the overlying roof collapses periodically, pay attention to the compression amount and bearing capacity of the strip filling body in a timely manner.

2. The structural filling mining method combining gabion mesh masonry - grouting - shotcreting after the support according to claim 1, characterized in that: In step (1), the height of the strip filling body is comprehensively determined according to the gangue output of the working face and the height of the goaf, ensuring that all the gangue produced at the working face is utilized and the purpose of not lifting the gangue out of the well is achieved; according to the height H of the goaf at the working face and the width A of the working face, determine the height h, width a, and spacing b between the filling bodies of the strip filling in the goaf, that is, H = h, a / (a + b) = 0.2 - 0.3; determine the filling rate V according to the advancing speed of the working face, and require the filling rate to be consistent with the advancing speed of the working face.

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

4. The structural filling mining method combining gabion mesh masonry, grouting and shotcreting behind the support according to claim 1, characterized in that: The special filling hydraulic support includes a hydraulic support main body, a lifting and stacking device, a grouting device, and a baffle. The support top beam extends backward on the basis of the hydraulic support main body to cover the transportation of the gabion net masonry blocks during on-site construction; a lifting and stacking device, a grouting device, and a support baffle are arranged behind the hydraulic support main body. 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 spraying pipe and a spraying pipe slide rail; a support baffle is arranged vertically behind the hydraulic support main body, and a spraying pipe slide rail is arranged vertically on the support baffle, and a spraying pipe is arranged perpendicular to the spraying pipe slide rail; the spraying pipe is arranged horizontally.

5. The structural backfilling mining method by combining gabion mesh masonry - grouting - shotcreting after the support according to claim 1, characterized in that: Determine the size of the box-shaped gabion net according to the size and shape of the gangue produced by underground sorting, ensuring that the size of the gangue filler in the box-shaped gabion net is more than 1.5 times the mesh size; after the box-shaped gabion net is processed into the designed size, line it with a layer of tightly woven nylon net before filling with gangue underground; the gabion net is selected from one of low-carbon steel wire, lead wire gabion net, plastic-coated gabion net, and galvanized gabion net.

6. The structural filling mining method combining the gabion mesh masonry, grouting and shotcreting behind the support according to claim 1, characterized in that: During the filling process in step (4), vibrate the gabion net to ensure that the internal gangue filler is fully in contact; it is required that after the gangue filler is filled and sealed, the internal void ratio is less than 35%.

7. The structural filling mining method by combining the post-frame gabion mesh masonry, grouting and shotcreting according to claim 1, characterized in that: Arrange one or more grouting pipes inside the dry-laid stone strip wall. The grouting pipes are designed as connectable short pipes and are connected and extended according to the length of the working face; during the spraying process, the box-shaped gabion net and the lined nylon net act as hanging nets to ensure the adhesion effect of the surface slurry during the spraying process.

8. The structural backfill mining method combining the gabion mesh masonry, grouting and shotcreting behind the support according to claim 7, characterized in that: The aggregate in the cement mortar during shotcreting is the gangue debris and powder with a particle diameter less than 1 cm in the underground gangue. The mass ratio of the slurry in the cement mortar is: cement∶aggregate∶water = 1~1.2∶3~3.5∶0.5~0.6, and the dosage of the accelerator is 3%~5% of the total slurry mass; and during shotcreting, the working wind pressure is greater than 0.5 MPa, and the shotcreting thickness is greater than 40 mm.

9. The structural filling mining method combining post-frame gabion mesh masonry - grouting - shotcreting according to claim 1, characterized in that: During the stacking process of the filled gabion mesh masonry blocks, along the length direction of the filling body, the tie bolts are arranged at intervals of 2 m~10 m; the deformation of the strip filling body in the width direction is restricted by the trays at both ends of the tie bolts, and at the same time, the area of the bolt trays on both sides of the wall is increased to enhance the bearing capacity.

10. The structural backfilling mining method combining stone cage net masonry - grouting - shotcreting after the support according to claim 9, characterized in that: The length of the tie bolts arranged inside the wall matches the width a of the filling body. The length of the tie bolts is 1.05 times~1.15 times the width a of the filling body, and the installation dimension of the bolt trays is reserved to ensure that the transverse deformation of the strip gangue can be effectively restricted under the constraint of the large-area bolt trays at both ends, and the integrity of the gabion gangue wall after grouting is enhanced.

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