Advanced support method for return airway of coal face applied to soft coal seam

Abstract

The invention provides a coal face return airway advance support method applied to a soft coal seam, which comprises the following steps: S1, setting a plurality of support points at intervals along the extension direction of a return airway of a coal face, and the plurality of support points are positioned on the non-stoping side of the return airway; s2, a plurality of sleeves which are sequentially stacked in the height direction of the roadway are arranged at the supporting points, a top mold bag is installed on the uppermost sleeve to form a pier column template, and a material injection opening is formed in the top mold bag; and S3, concrete is poured into the pier column formwork through the material injection opening till the top formwork bag makes contact with a top plate of the air return way, so that a supporting pier column is formed. According to the forepoling method, the multiple sleeves capable of being stacked in the height direction are used for being matched with the top formwork bags, the height of the supporting pier column is flexibly adjusted, the roof contact effect is ensured so as to adapt to the return airway with the continuously-changing height, and compared with existing support supporting, disturbance to the soft coal seam is greatly reduced; and the operation risk of sinking and collapsing of the goaf roof under the soft coal seam condition is avoided.

Description

Technical Field

[0001] The present disclosure relates to the technical field of advance support, and in particular to an advance support method for a return air lane of a coal mining face applied to a soft coal seam. Background Art

[0002] At present, the existing advance support forms for the return air lanes of coal mining working faces in domestic underground coal mines are generally hydraulic support or scaffolding support. However, when faced with extremely soft coal seam conditions with "three softs" (soft roof, soft bottom, and soft coal seam), the roof and floor plates of the coal seams may turn into mud when exposed to water and turn into sand when exposed to wind. If hydraulic unit supports or scaffolding support are used as advance support, the unit supports need to repeatedly perform the "lowering-moving-raising" process to support the roof plate multiple times when the working face advances. When the working face is mined, the scaffolding support needs to frequently perform the "beam raising, pillar support, pillar removal, and pillar transportation" process, which will cause the roof and floor plates to be frequently damaged by the support, resulting in prominent roof plate subsidence around the support structure and serious bottom bulging of the roadway. There are also great safety risks, and the support structure may be crushed or broken and have to be abandoned. Therefore, there is an urgent need for an effective, reliable, and safe advance support method to solve the problem of return air advance range roadway support in coal mining working faces under soft coal seam conditions. Summary of the Invention

[0003] A technical problem to be solved by the present disclosure is: how to effectively support the return air advance range of the coal mining face under soft coal seam conditions.

[0004] In order to solve the above technical problems, the embodiment of the present disclosure provides an advance support method for the return air lane of a coal mining face applied to a soft coal seam, including: S1, setting multiple support points at intervals along the extension direction of the return air lane of the coal mining face, and the multiple support points are located on the non-mining side of the return air lane; S2, arranging multiple sleeves stacked in sequence along the height direction of the lane at the support points, and installing a top mold bag on the uppermost sleeve to form a pier column template, and the top mold bag is provided with an injection port; S3, pouring concrete into the pier column template through the injection port until the top mold bag contacts the top plate of the return air lane to form a support pier.

[0005] In some embodiments, anchor holes are provided on the sleeves. In S2 , before stacking the sleeves, tension anchors are installed on the sleeves through the anchor holes.

[0006] In some embodiments, in S2, before stacking the sleeves, miner steel is placed axially in the sleeves, and the miner steel is welded to the tension anchor rods.

[0007] In some embodiments, the top mold bag is installed inside the uppermost sleeve. In S2, before installing the top mold bag, a fixing hole is opened on the top mold bag, and a tension anchor rod is passed through the anchor rod hole and the fixing hole to fix the top mold bag to the inner surface of the sleeve.

[0008] In some embodiments, threaded sections and pads sleeved on the threaded sections are provided at both ends of the tension anchor rod. In S2, after the tension anchor rod is installed, the pads are fixed to the outer surface of the pier formwork through nuts.

[0009] In some embodiments, connecting flanges are provided at both ends of the sleeve, and two sleeves adjacent to each other in the height direction are connected via the connecting flanges.

[0010] In some embodiments, a plurality of hoops spaced apart along the height direction are provided on the outer periphery of the pier column formwork.

[0011] In some embodiments, in S2, before forming the pier column formwork, a bottom formwork bag is provided at the bottom of the lowest sleeve.

[0012] In some embodiments, in S3, before pouring concrete, a hydraulic single-body support is set up in the return air channel, and the hydraulic single-body support is fixedly connected to the pier column formwork to improve the stability of the pouring process.

[0013] In some embodiments, the injection port is divided into three layers. In S3, during pouring, the outer two layers of the injection port are fixedly sleeved on the outer periphery of the grouting hose, and the innermost layer faces the inside of the top mold bag.

[0014] Through the above-mentioned technical solution, the present invention provides an advanced support method for the return air lane of the coal mining working face applied to soft coal seams. It uses multiple sleeves that can be stacked in the height direction in combination with top mold bags to flexibly adjust the height of the support piers and ensure the top connection effect to adapt to the return air lane with constantly changing height. Compared with the existing bracket support, it simplifies the construction process, greatly reduces the disturbance to the soft coal seam, and improves the support strength. In addition, the support piers are set on the non-mining side of the return air lane, so that the piers can be exempted from cutting during the mining process, eliminating the operational risks of sinking and collapse of the goaf roof under soft coal seam conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 It is a structural schematic diagram of the pier column template disclosed in the embodiment of the present disclosure;

[0017] Figure 2 It is a partial structural diagram showing the clamp and the connecting flange disclosed in the embodiment of the present disclosure;

[0018] Figure 3It is a partial structural schematic diagram showing the top mold bag and the bottom mold bag disclosed in the embodiment of the present disclosure;

[0019] Figure 4 It is a schematic structural diagram showing a tension anchor rod and a miner steel according to an embodiment of the present disclosure;

[0020] Figure 5 is a top cross-sectional view of the return air channel disclosed in the embodiment of the present disclosure;

[0021] Figure 6 It is a front cross-sectional view of the return air duct disclosed in the embodiment of the present disclosure.

[0022] Description of reference numerals:

[0023] 1. Return air lane; 101. Top plate; 102. Bottom plate; 2. Sleeve; 3. Top formwork bag; 4. Pier formwork; 5. Injection port; 6. Grouting hose; 7. Tension anchor rod; 8. Miner steel; 9. Pad; 10. Connecting flange; 11. Hoop; 12. Bottom formwork bag; 13. Hydraulic single pillar; 14. Support pier. DETAILED DESCRIPTION

[0024] The following embodiments of the present disclosure are further described in detail with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present disclosure, but are not intended to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0025] The present disclosure provides these embodiments in order to make this disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0026] It should be noted that, in the description of this disclosure, unless otherwise specified, "plurality" means greater than or equal to two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are intended solely to facilitate and simplify the description of this disclosure, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0027] In addition, the terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different parts. "Perpendicular" does not mean perpendicular in the strict sense, but rather means within the tolerance range. "Parallel" does not mean parallel in the strict sense, but rather means within the tolerance range. "Include" or "comprising" and similar terms mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements.

[0028] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this disclosure depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0029] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0031] like Figures 1-6 As shown, the present disclosure provides a method for advanced support of the return air lane of a coal mining face applied to a soft coal seam, comprising: S1, setting a plurality of support points at intervals along the extension direction of the return air lane 1 of the coal mining face, and the plurality of support points are located on the non-mining side of the return air lane 1; S2, arranging a plurality of sleeves 2 stacked in sequence along the height direction of the lane at the support points, and installing a top mold bag 3 on the uppermost sleeve 2 to form a pier column formwork 4, and a material injection port 5 is opened on the top mold bag 3; S3, pouring concrete into the pier column formwork 4 through the material injection port 5 until the top mold bag 3 contacts the top plate 101 of the return air lane 1 to form a support pier 14.

[0032] Specifically, in S1, the spacing between adjacent support points is set between 2m and 3m, providing sufficient support strength for the return air tunnel 1. At the same time, the support points are set on the non-mining side of the return air tunnel 1, and a mining channel of 60%-80% of the entire tunnel width is left on one side. The mining channel is used for working face mining operations, so that the support piers 14 can be exempted from cutting during the mining process. Compared with traditional hydraulic unit supports or shed supports, the disturbance to the coal seam is greatly reduced, so as to effectively cope with the working conditions of weak coal seams. In addition, the non-cutting setting of the support piers 14 not only reduces the disturbance to the coal seam, but also reduces the load of the coal mining machine and the loss of the cutting teeth, and eliminates the accidental injury caused by concrete splashing during cutting, and avoids the impact of concrete fragments mixed into the coal flow on the coal quality. Figure 5 and Figure 6 As shown, in some embodiments, taking a return airway 1 with a width of 5m and a lead support length of 50m as an example, the support points are set 3.5m away from one side of the return airway 1, leaving space for mining operations. The diameter of the support piers 14 is 0.8m, and the spacing between adjacent support points is 2.4m. In other embodiments, the setting positions and dimensions can also be appropriately adjusted according to actual conditions.

[0033] In S2, since the height of the return air channel 1 is constantly changing in the extension direction and the top plate 101 is not flat, a plurality of stackable sleeves 2 are used in conjunction with the top formwork bag 3 to form the pier formwork 4, which can flexibly adapt to the return air channel 1 and provide stable and effective support for it. For ease of installation, before stacking a plurality of sleeves 2, the top formwork bag 3 is fixed on one of the sleeves 2, and the sleeve 2 is placed at the top of the pier formwork 4 when stacking. A space of at least 500mm is maintained between the top of the sleeve 2 and the top plate 101 for placing the top formwork bag 3. After pouring, the top formwork bag 3 needs to be filled and fit the top plate 101. Among them, the sleeve 2 can be made of 0.75mm thick galvanized iron sheet, and the height can be 1m or 1.25m. It can also be processed into segments of different lengths according to actual needs. The diameter of the sleeve 2 can be selected from 600mm-1000mm, such as Figure 4 As shown, the diameter of the sleeve 2 of this embodiment is 800 mm; the top mold bag 3 is a flexible mold bag woven with high-strength flexible material, which is filled with internal filling materials (such as concrete or mortar, etc.) to fit the irregular wall surface and thus achieve the purpose of adapting to complex construction environments.

[0034] In S3, the grouting hose 6 is connected to the injection port 5, and concrete is poured into the pier column formwork 4. As the amount of pouring increases, the top formwork bag 3 gradually fills until it contacts the top plate 101. The flexibility of the top formwork bag 3 is utilized to achieve effective contact with the top, thereby improving the support effect of the supporting pier column 14. In order to prevent the top formwork bag 3 from shifting when filled, multiple pull rings can be provided above the top formwork bag 3, and corresponding anchor hooks can be provided on the top plate 101. Before pouring, the top formwork bag 3 is fixed relative to the top plate 101 by connecting the pull rings and the anchor hooks to ensure the forming effect of the supporting pier column 14. During on-site operations, the distance between the injection port 5 and the top plate 101 is preferably 150mm-200mm. A HBMD80 / 16-110S mining concrete pump is used to pump C40 concrete into the pier column formwork 4 through the injection port 5 to form the supporting pier column 14.

[0035] In some embodiments, the pier column formwork 4 is not removed after pouring is completed, and is combined with the concrete material inside it to form a supporting pier column 14. The pier column formwork 4 cooperates with the top plate 101 and the bottom plate 102 to put the internal concrete in a three-way compression state, effectively restraining the generation and development of cracks inside the structure, so as to improve the compressive strength and deformation resistance of the supporting pier column 14.

[0036] like Figure 4 As shown, in some embodiments, anchor holes are provided on the sleeve 2. In S2, before stacking the sleeves 2, tension anchors 7 are installed on the sleeves 2 through the anchor holes.

[0037] Specifically, a group of tension anchor rods 7 is composed of two anchor rods arranged in a cross shape. The tension anchor rods 7 are inserted into the anchor rod holes pre-opened on the sleeve 2, and then the sleeves 2 with the tension anchor rods 7 are stacked in sequence along the height direction. Figure 4 As shown, after stacking to form the pier formwork 4, multiple sets of tension anchor rods 7 are spaced apart along the height direction to enhance the load-bearing capacity of the supporting pier 14. For example, for a supporting pier 14 with a diameter of 800 mm, the tension anchor rods 7 can be two screw rods with a diameter of 22 mm and a length of 1200 mm. The spacing between two adjacent sets of tension anchor rods 7 along the height direction is 400 mm. In other embodiments, the specifications and spacing of the anchor rods can be adjusted appropriately.

[0038] like Figure 4 As shown, in some embodiments, in S2 , before stacking the sleeve 2 , a miner steel 8 is placed axially in the sleeve 2 , and the miner steel 8 is welded to the tension anchor 7 .

[0039] Specifically, to further enhance the support strength of the support pier 14, after the tension anchor 7 is installed, a piece of miner steel 8 is placed near the axis of each sleeve 2 and welded to the two anchors to complete the fixation. After the miner steel 8 in each sleeve 2 is installed, they are stacked to form the pier formwork 4. Multiple miner steels 8 are placed sequentially near the axis of the pier formwork 4, which can effectively enhance the bearing capacity of the support pier 4 after casting. Miner steel 8 is a commonly used component for mine roadway support and is easy to obtain. In other embodiments, other types of reinforcing components may also be used.

[0040] In some embodiments, as Figure 4 As shown, the length of the miner steel 8 is 300mm-500mm longer than the corresponding sleeve 2, and the excess length is evenly distributed at the top and bottom of the sleeve 2. The miner steel 8 inside the sleeve 2 at the end of the pier column formwork 4 does not exceed the range of the pier column formwork 4. The miner steels 8 in the two adjacent sleeves 2 are respectively welded in the two relative angles of the tension anchor rod 7. The multiple miner steels 8 located in the pier column formwork 4 are overlapped end to end, which is convenient for workers to operate while ensuring the structural strength.

[0041] In some embodiments, the top mold bag 3 is installed inside the sleeve 2 located at the top. In S2, before installing the top mold bag 3, a fixing hole is opened on the top mold bag 3, and the tension anchor rod 7 is passed through the anchor rod hole and the fixing hole to fix the top mold bag 3 to the inner surface of the sleeve 2.

[0042] Specifically, the top mold bag 3 is a flexible mold bag with an opening facing downward and connected to the sleeve 2. The mold bag surface at its opening is in contact with the inner surface of the uppermost sleeve 2. In S2, before stacking the sleeves 2, the top mold bag 3 is placed in the sleeve 3, and the fixing holes are aligned with the anchor holes. The tension anchors 7 are then inserted to fix the top mold bag 3 to the inner surface of the sleeve 2, which can effectively reduce the occurrence of slurry leakage during pouring. To improve the fixing effect of the top mold bag 3, in some embodiments, a pressure plate can be installed on the tension anchor 7 to compact the top mold bag 3 against the inner surface of the sleeve 2 using the pressure plate to prevent the top mold bag 3 from shifting due to vibration during the pouring process.

[0043] like Figure 4 As shown, in some embodiments, both ends of the tension anchor rod 7 are provided with threaded sections and pads 9 sleeved on the threaded sections. In S2, after the tension anchor rod 7 is installed, the pads 9 are fixed to the outer surface of the pier column formwork 4 by nuts.

[0044] Specifically, after installing the tension anchor rods 7 and forming the pier column formwork 4, nuts are sleeved on both ends of the tension anchor rods 7, and the threaded sections are used to press the pads 9 against the outer surface of the pier column formwork 4. By rotating the nuts to adjust the pressing force of the pads 9, the outer surface of the pier column formwork 4 formed by stacking multiple sleeves 2 can be made as flat as possible. At the same time, the pads 9 can effectively disperse the tightening pressure to avoid stress concentration that causes local deformation of the galvanized iron plate. The pads 9 can be made of 10*150*150mm iron plates. After the poured concrete reaches a certain strength, the pads 9 can be removed and reused to reduce production costs.

[0045] like Figure 1 and Figure 2 As shown, in some embodiments, connecting flanges 10 are provided at both ends of the sleeve 2 , and two sleeves 2 adjacent to each other in the height direction are connected via the connecting flanges 10 .

[0046] Specifically, in order to improve the stability of the pier column formwork 4 and ensure the safety of the pouring process, a connecting flange 10 is provided between two adjacent sleeves 2, such as Figure 2 As shown, the connecting flange 10 can be made of 40*40*4mm angle iron into an annular structure around the outer circumference of the sleeve 2 and fixed to the sleeve 2 using 8mm bolts. Two adjacent connecting flanges 10 can be connected by bolts. The connecting flanges 10 effectively increase the connection strength and contact area between the sleeves 2, thereby improving the stability of the pier column formwork 4. The bottom and top ends of the pier column formwork 4 are not provided with connecting flanges 10.

[0047] like Figure 1 and Figure 2 As shown, in some embodiments, a plurality of hoops 11 spaced apart along the height direction are provided on the outer periphery of the pier column formwork 4 .

[0048] Specifically, the hoop 11 can be formed from a flat iron with a thickness of 4 mm and a width of 30 mm to form an annular structure around the outer perimeter of the pier column formwork 4. A 10 mm diameter circular hole is provided at intervals of 400 mm along its circumference. Bolts with a diameter of 8 mm are then used to secure the hoop 11 to the pier column formwork 4. Multiple hoop 11s can be provided on the pier column formwork 4 at intervals of 200 mm along the height direction. In other embodiments, the size and spacing of the hoop 11 can be appropriately adjusted.

[0049] like Figure 1 As shown, in some embodiments, in S2 , before forming the pier column formwork 4 , a bottom mold bag 12 is provided at the bottom of the lowest sleeve 2 .

[0050] Specifically, before stacking multiple sleeves 2, the bottom mold bag 12 is opened upward and placed on the outer periphery of the sleeve 2 located at the bottom. The mold bag surface at its opening is attached to the outer surface of the sleeve 2, and then tied with double-strand galvanized iron wire to prevent the unevenness of the bottom plate 102 of the return air channel 1 from causing slurry leakage during pouring. By utilizing the characteristics of the flexible mold bag that is water-permeable but not slurry-permeable, the water-cement ratio during pouring can be appropriately increased to enhance the workability of the concrete for pouring. During the pouring process, excess water seeps out from the bottom mold bag 12, thereby achieving high water-cement ratio transportation and low water-cement ratio hardening, quickly improving early strength. At the same time, the excess water seeps out in the early stage of pouring, which can effectively reduce the hydration shrinkage of the support pier 14 in the later stage and avoid incomplete top connection, which not only reduces the difficulty of pouring but also ensures the structural strength of the support pier 14.

[0051] like Figure 5 and Figure 6 As shown, in some embodiments, in S3, before pouring concrete, a hydraulic single-body support 13 is set in the return air channel 1, and the hydraulic single-body support 13 is fixedly connected to the pier column formwork 4 to improve the stability of the pouring process.

[0052] Specifically, if Figure 5 and Figure 6 As shown, before pouring, a hydraulic single pillar 13 is set on both sides of the pier column formwork 4. The two ends of the hydraulic single pillar 13 respectively contact the top plate 101 and the bottom plate 102 of the return air channel 1, and are parallel to the pier column formwork 4. Double-strand galvanized iron wire is then used to tie the pier column formwork 4 and the hydraulic single pillar 13 to ensure the stability of the pier column formwork 4 during the pouring process. As the working surface advances, the hydraulic single pillars 13 on both sides of the supporting pier column 14 can be gradually recovered.

[0053] like Figure 1 and Figure 3 As shown, in some embodiments, the injection port 5 is divided into three layers. In S3, during pouring, the two outer layers of the injection port 5 are fixedly sleeved on the outer periphery of the grouting hose 6, and the innermost layer faces the inside of the top mold bag 3.

[0054] Specifically, the diameter of the injection port 5 is 100mm-150mm, and the length is 300mm-500mm. When preparing for pouring, the two outer layers of the injection port 5 are tied to the outer periphery of the grouting hose 6 by double-strand iron wire to ensure the stable connection between the grouting hose 6 and the injection port 5, and prevent the interface from falling off under the pumping pressure. The double-layer connection can effectively disperse the vibration of the pump pipe and the impact force of the concrete, reduce the occurrence of tearing of the flexible mold bag, and when one of the layers is torn, it is also easy to find and suspend the pouring in time for repair, to avoid sudden pipe burst. The inner layer of the flexible mold bag forms a guiding structure during the pouring process, which smoothly guides the pumped concrete into the top mold bag 3, avoiding the aggregate in the concrete directly impacting the inner surface of the mold bag and causing local damage. At the same time, the inner layer of the injection port 5 is in a closed state before pouring, and opens under the pumping pressure for guidance during pouring. After pouring is completed, the top mold bag 3 is sealed under the squeezing action of the internal concrete, which plays a role in preventing slurry leakage.

[0055] The following describes the advanced support method for the return air lane of a coal mining face in a soft coal seam in combination with the embodiments disclosed herein:

[0056] S1, such as Figures 1-6 As shown, the tunnel width is 5m, and a row of support points is set at a position 3.5m away from one side of the return air tunnel 1 to reserve a mining channel, and the interval between adjacent support points is 2.4m;

[0057] S2. Prepare multiple sleeves 2 with a diameter of 800 mm. Insert the tension anchor rods 7 through the anchor holes pre-opened on the surface of the sleeves 2. Place a miner steel 8 in each sleeve 2 and weld the miner steel 8 to the tension anchor rod 7 to secure them. Install the top mold bag 3 and the bottom mold bag 12 on the corresponding sleeves 2 respectively. Finally, stack the processed sleeves 2 to form the pier column formwork 4.

[0058] S3. Before pouring, hydraulic single pillars 13 are set on both sides of the pier column formwork 4 and connected with double-strand wires. The grouting hose 6 is fixed to the injection port 5 for pouring. The pouring is carried out until the top formwork bag 3 is filled and contacts the top plate 101, and the construction of the supporting pier column 14 is completed.

[0059] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0060] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A method for advanced support of return air lane in coal mining working face applied to soft coal seams, characterized in that: include: S1, setting a plurality of support points at intervals along the extension direction of the return air lane (1) of the coal mining working face, wherein the plurality of support points are located on the non-mining side of the return air lane (1); S2, arranging a plurality of sleeves (2) stacked in sequence along the height direction of the tunnel at the support point, and installing a top mold bag (3) on the sleeve (2) located at the top to form a pier column template (4), wherein the top mold bag (3) is provided with a material injection port (5); S3. Concrete is poured into the pier column formwork (4) through the injection port (5) until the top formwork bag (3) contacts the top plate (101) of the return air channel (1), so as to form a supporting pier column (14).

2. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1 is characterized in that: An anchor rod hole is provided on the sleeve (2). In S2, before stacking the sleeves (2), a tension anchor rod (7) is installed on the sleeve (2) through the anchor rod hole.

3. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 2 is characterized in that: In S2, before stacking the sleeves (2), a miner steel (8) is placed in the sleeves (2) along the axial direction, and the miner steel (8) is welded to the tension anchor rod (7).

4. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 2 is characterized in that: The top mold bag (3) is installed inside the sleeve (2) located at the top. In S2, before installing the top mold bag (3), a fixing hole is opened on the top mold bag (3), and the tension anchor rod (7) passes through the anchor rod hole and the fixing hole to fix the top mold bag (3) to the inner surface of the sleeve (2).

5. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 2 is characterized in that: Both ends of the tension anchor rod (7) are provided with threaded sections and pads (9) sleeved on the threaded sections. In S2, after the tension anchor rod (7) is installed, the pads (9) are fixed to the outer surface of the pier column formwork (4) through nuts.

6. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1 is characterized in that: Connecting flanges (10) are provided at both ends of the sleeve (2), and two sleeves (2) adjacent to each other in the height direction are connected via the connecting flanges (10).

7. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1 is characterized in that: The outer periphery of the pier column template (4) is provided with a plurality of hoops (11) distributed at intervals along the height direction.

8. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1 is characterized in that: In S2, before forming the pier column formwork (4), a bottom mold bag (12) is provided at the bottom of the sleeve (2) located at the bottom.

9. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1 is characterized in that: In S3, before pouring concrete, a hydraulic single-body support (13) is installed in the return air channel (1), and the hydraulic single-body support (13) is fixedly connected to the pier column formwork (4) to improve the stability of the pouring process.

10. The method for advanced support of return air lane in coal mining working face applied to soft coal seam according to claim 1, characterized in that: The injection port (5) is divided into three layers. In S3, when pouring, the outer two layers of the injection port (5) are fixedly sleeved on the outer periphery of the grouting hose (6), and the innermost layer faces the inside of the top mold bag (3).

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