A method for retaining roadway along gob with reconstructed load-bearing arch for broken roof

Abstract

The present invention discloses a method for retaining a lane along the goaf by reconstructing a bearing arch from a broken roof, which belongs to the technical field of retaining a lane along the goaf. The method for retaining a lane along the goaf by reconstructing a bearing arch from a broken roof includes the following steps: lane expansion and brushing, roof maintenance, goaf blocking, foundation construction, template installation, pouring, curing and demoulding. The method comprises installing foundation steel bars and a steel skeleton in conjunction with the template during foundation construction between the coal mining area and the goaf, and then pouring to form a bearing arch to support the broken roof of the lane along the goaf. Even if the original support is deformed and fails, or the roof falls off, the bearing arch support of the present invention greatly reduces the risk of roof falling off in the lane along the goaf.

Description

Technical Field

[0001] The invention relates to the technical field of gob-side tunnel retaining, and in particular to a gob-side tunnel retaining method for reconstructing a bearing arch from a broken roof. Background Art

[0002] Gob-side entry retention technology has long been a key technological development in my country's coal mining industry. Gob-side entry retention involves maintaining the original entryway along the edge of the goaf after the working face has been mined. The entryway from the previous working face is preserved using specific support measures and used as the working face for the next section. This eliminates the need to excavate one entryway in the next section, reducing gas control and water exploration and drainage costs while easing the pressure of mining transitions. Pillarless mining is crucial for conserving coal resources and extending the lifespan of mines.

[0003] At present, the technical means of retaining a lane along the goaf are usually support inside the lane and beside the lane, and research mainly focuses on support beside the lane. The filling wall is constructed by filling gangue, concrete, high-water materials and other materials in woven bags. The filling wall blocks the gangue in the goaf and cuts off the side roof of the wall in the goaf, turning the long arm into a short arm. The above-mentioned method of retaining a lane along the goaf by filling the wall with various materials beside the goaf may cause the roof to be cut off at different positions in the roof of the lane. Under the influence of mining pressure, the support of the broken roof fails, the roof becomes unstable, and the risk of local roof collapse or large-scale roof collapse is greatly increased. Therefore, for this kind of broken roof, it is difficult to successfully retain a lane using the current method of retaining a lane along the goaf, and the safety risks are extremely high, which makes the development of the technology of retaining a lane along the goaf subject to certain obstacles under different geological conditions. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problem of difficulty in retaining a lane along the gob by crushing the existing roof, and to provide a method for retaining a lane along the gob by reconstructing a bearing arch by crushing the roof.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for retaining a gob-side entry by reconstructing a bearing arch by breaking a roof, used for gob-side entry retaining support construction, comprises the following steps:

[0007] a. Roadway expansion: The roadway between the coal mining area and the goaf is expanded to form a goaf-side roadway as required by the design;

[0008] b. Roof maintenance: Install end supports at the end of the mining face, and install temporary supports on the broken roof along the side of the gob as temporary support;

[0009] c. Goaf retaining wall: set up retaining wall pillars along the length of the goaf;

[0010] d. Foundation construction: After the roadway is expanded, undercover construction is carried out on the vertical wall of the coal mining area and along the length of the goaf. Foundation steel bars are embedded vertically above the undercover and arranged along the length of the vertical wall of the coal mining area and the length of the goaf. A steel frame is installed above the foundation steel bars. The foundation steel bars on both sides of the roadway are connected to the same steel frame to form an arched frame support structure.

[0011] e. Template installation: In step d, the template is installed on the inner side of the arch of the arch skeleton and on the outer side of the arch on the goaf side, and a first plugging plate is installed at both ends of the template. The template and the first plugging plate constitute a casting template;

[0012] f. Pouring: After the formwork is installed, grouting is carried out in the arch frame using a grouting pump;

[0013] g. Curing: Curing is carried out for 2-3 days after the grouting is completed;

[0014] h. Demoulding: After curing, remove the formwork inside and outside the load-bearing arch in step e.

[0015] Preferably, in step e, the casting template includes an inner tunnel arch template and an outer tunnel arc template. The inner tunnel arch template, which is precisely positioned with the arch skeleton, is installed on the inner side of the arch skeleton, and the outer tunnel arc template, which is precisely positioned with the arch skeleton and adjacent to the slag retaining column, is installed on the outer side of the arch skeleton on the goaf side. A first plugging plate is installed at both ends of the inner tunnel arch template and the outer tunnel arc template. The inner tunnel arch template, the outer tunnel arc template and the first plugging plate constitute a casting template.

[0016] Preferably, the in-lane arch formwork adopts a first U25 steel arc structure, and an arc steel plate is welded on the outside of the first U25 steel. The in-lane arch formwork is assembled from 4 or 6 sections, and a first arc connecting plate is welded at both ends of the upper part of the in-lane arch formwork. The first arc connecting plate is provided with a first through hole connected to the first plug plate.

[0017] Preferably, the arc-shaped template outside the lane adopts a second U25 steel arc structure, and the lane outside is assembled from at least two sections of the second U25 steel. A second arc-shaped connecting plate is welded at both ends of the arc-shaped template outside the lane, and a second through hole connected to the first plug plate is opened on the second arc-shaped connecting plate.

[0018] Preferably, in step e, the casting formwork includes a formwork trolley and a slurry retaining plate. The formwork trolley is driven into the tunnel so that the formwork trolley and the arch frame are precisely positioned. The slurry retaining plate is installed on the outside of the arch frame on the goaf side, and the second plugging plates are installed at both ends of the outer side of the formwork trolley. The formwork trolley, the slurry retaining plate and the second plugging plate constitute a casting column formwork for casting support.

[0019] Preferably, a single column is provided on the goaf side and is adjacent to the slurry retaining plate.

[0020] Preferably, in step d, the undercover has a steel cage, the undercover is cast with concrete, and the upper part of the undercover along the length direction of the coal mining area and along the side of the goaf has a foundation platform, and the lower end of the foundation steel bar extends upward from the steel cage.

[0021] Preferably, the foundation platform along the vertical wall direction of the coal mining area is in an L-shaped structure, and the foundation platform along the length direction of the goaf area side is in a convex-shaped structure.

[0022] Preferably, the steel frame is a semicircular frame assembled from steel bars.

[0023] Preferably, in step h, the template on the inner side of the arch frame can be removed later according to the pressure along the gob tunnel section, and the template on the inner side of the arch frame serves as a temporary reinforcement support.

[0024] The present invention has the following beneficial effects:

[0025] 1. In the present invention, by installing foundation steel bars and a steel skeleton in conjunction with a formwork between the coal mining area and the goaf, and then pouring to form a bearing arch to support the broken roof of the goaf-side tunnel, even if the original support deforms and fails, and the roof collapses, the bearing arch support of the present invention greatly reduces the risk of roof collapse in the goaf-side tunnel. The goaf-side tunneling method of the present invention is simple, easy to implement, and suitable for promotion and application.

[0026] 2. In the present invention, the bearing arch is a semicircular arch, which has higher strength when supporting the top plate and is more capable of resisting deformation of the surrounding rock. It effectively prevents the occurrence of broken top plate collapse and provides a guarantee for the construction safety of the workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of the method of retaining a gob-side entry by recreating a bearing arch by breaking the roof;

[0028] Figure 2 Schematic diagram of the gob-side tunnel retaining construction layout in the present invention;

[0029] Figure 3 2 is a schematic cross-sectional view of a gob-side entry retaining in Example 2 of the present invention;

[0030] Figure 4 Schematic diagram of a bearing arch gob-side entry retaining in Example 2 of the present invention;

[0031] Figure 5 yes Figure 4 A in the middle is an enlarged schematic diagram;

[0032] Figure 6 Schematic diagram of the arched template inside the lane and the curved template outside the lane in Example 2 of the present invention;

[0033] Figure 7 3 is a schematic diagram of the installation of the steel frame of the present invention in Example 3 of the present invention;

[0034] Figure 8 Schematic diagram of a gob-side entry retaining with a bearing arch in Example 3 of the present invention;

[0035] Figure 9 This is a schematic diagram of the installation of foundation steel bars and steel cages in the present invention;

[0036] Figure markings: 1-coal mining area; 2-goaf area; 3-foundation steel bars; 4-steel skeleton; 5-end support; 6-arch skeleton; 7-temporary support; 8-slag retaining column; 9-arch formwork inside the tunnel; 10-arc formwork outside the tunnel; 11-first plugging plate; 12-tunnel along the goaf; 13-first U25 steel; 14-foundation platform; 15-first arc-shaped connecting plate; 16-second U25 steel; 17-second arc-shaped connecting plate; 18-template trolley; 19-slurry retaining plate; 20-single column; 21-second plugging plate; 22-steel cage; 23-anchor rod. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in further detail. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0038] Example 1

[0039] like Figure 1-9 As shown, a method for retaining a gob-side entry by reconstructing a bearing arch by breaking a roof is used for gob-side entry retaining support construction, comprising the following steps:

[0040] a. Roadway expansion: The roadway between the coal mining area 1 and the goaf area 2 is expanded to form a goaf-side roadway 12 as required by the design;

[0041] b. Roof maintenance: Install the end bracket 5 at the end of the mining face, and install a temporary bracket 7 on the broken roof along the empty roadway 12 side as a temporary support;

[0042] c. Goaf retaining rock: rock retaining rock columns 8 are set along the length direction of the goaf 2;

[0043] d. Foundation Construction: After the roadway is expanded, undercover construction is carried out at the vertical wall position of the coal mining area 1 and along the length of the side of the goaf 2. Foundation steel bars 3 are pre-embedded in the upper part of the undercover, extending vertically upward and along the length of the vertical wall of the coal mining area 1 and the length of the side of the goaf 2. A steel skeleton 4 is installed above the foundation steel bars 3. The foundation steel bars 3 on both sides of the roadway are connected to the same steel skeleton 4 to form an arch skeleton 6 supporting the structure;

[0044] e. Template installation: In step d, the template is installed on the inner side of the arch frame 6 and the outer side of the arch located on the goaf 2 side, and the first plugging plate 11 is installed at both ends of the template. The template and the first plugging plate 11 constitute a casting template;

[0045] f. Pouring: After the formwork is installed, grouting is performed in the arch frame 6 by a grouting pump;

[0046] g. Curing: Curing is carried out for 2-3 days after the grouting is completed;

[0047] h. Demolding: After curing, remove the templates inside and outside the arch frame 6 in step e to obtain the load-bearing arch.

[0048] When carrying out this embodiment, the mining tunnel between the coal mining area 1 and the goaf area 2 is expanded and brushed until it meets the design requirements. The expansion and brushing are carried out one section at a time. The expanded part is the goaf tunnel 12, and then the roof maintenance construction is carried out. The end support 5 is installed at the end of the mining working face area. The end support 5 is a hydraulic support. Then, wire mesh is laid on the broken top of the goaf tunnel 12 along the side of the goaf area 2, and anchor rods 23 are driven, and then concrete is sprayed as temporary support for the expansion and brushing area. The width of the temporary support area is 1-2m, and according to the degree of roof crushing and the pressure after the frame, when the degree of roof crushing is relatively large and the pressure is relatively large, a hydraulic single column or an articulated top beam should be constructed after the frame to strengthen the support of the roof. Then, a gangue retaining column 8 is driven on one side of the goaf tunnel 12 along the length direction of the goaf 2, and a bottom is laid along the vertical wall position of the coal mining area 1. The depth of the bottom is 500mm and the width of the bottom is 800mm. The underlay along the coal mining area 1 is carried out at a position 3200mm away from the underlay along the length direction of the goaf area 2. The underlay along the length direction of the goaf area 2 is carried out. The depth of the underlay along the goaf area 2 is 500mm, and the width of the underlay is 1300mm. Vertically upward foundation steel bars 3 are pre-embedded on the underlay along the coal mining area 1, and vertically upward foundation steel bars 3 are pre-embedded in the middle of the underlay along and along the goaf area 2. The foundation steel bars 3 are arranged along the length direction of the underlay. The foundation steel bars 3 on the underlay on both sides are connected to the same steel bar skeleton 4. The steel bar skeleton 4 is bent inward to form an arched skeleton 6. One end of the steel bar skeleton 4 is connected to the foundation steel bar 3 on the coal mining area side, and the other end of the steel bar skeleton 4 is connected to the foundation steel bar 3 on the goaf area 2 side. The steel bar skeleton 4 is connected to the foundation steel bar 3 on the goaf area 2 side. The steel bar skeleton 4 and the foundation steel bar 3 are connected to form an arched skeleton support structure, which is an arched skeleton 6. Then, formwork is installed on the inner side of the arch frame 6 and the outer side of the arch located on the goaf 2 side, and a first plugging plate 11 is installed at both ends of the formwork on the inner side of the arch frame 6. The first plugging plate 11 blocks both ends of the formwork, and the formwork and the first plugging plate 11 are connected to form a casting formwork. Then check whether the position where the first plugging plate 11 of the formwork is connected to the formwork is tight to prevent leakage during grouting due to the connection part not meeting the strict requirements. After checking that it meets the requirements, turn on the grouting pump to grout the arch frame 6. The slurry is configured and stirred on-site according to the designed water and ash ratio. During the grouting process, check at any time for leakage. If leakage occurs, deal with it in time. When the grouting liquid level is close to the arch top, grout slowly until the slurry fills the entire arch frame 6, then turn off the grouting pump to stop grouting. After grouting is stopped, the formwork is not removed yet and maintenance work should be carried out. The maintenance methods include but are not limited to regular and quantitative watering. The maintenance time should be 2-3 days. When the arch frame 6 reaches the design strength, the formwork is removed. First, the formwork on the inside of the arch frame 6 is removed, and then the formwork on the outside of the arch frame 6 is removed. After pouring slurry on the arch frame 6, it is maintained to form a load-bearing arch support structure along the goaf, and then the next section of construction can be carried out.

[0049] In this embodiment, by installing the foundation steel bars 3 and the steel skeleton 4 between the coal mining area 1 and the goaf 2 in conjunction with the formwork, and then pouring to form a bearing arch to support the broken roof of the goaf-retained tunnel, even if the original support fails to deform and the roof falls off, the risk of roof falling off in the goaf tunnel is greatly reduced due to the support of the bearing arch of this embodiment. By performing roof maintenance on the broken roof in the 1-2m area on one side of the goaf tunnel 12 in the goaf 2, the broken roof is prevented from falling off during the construction process, which affects the progress of construction and the construction safety of the workers. By setting up the slag retaining column 8 along the length of the goaf 2, the slag retaining column 8 prevents the slag from the goaf 2 from entering the goaf tunnel 12, affecting subsequent construction, and also ensuring the construction safety of the workers. By connecting the first plug plate 11 at both ends of the formwork, the work of pouring slurry in the bearing arch 11 is facilitated, and the phenomenon of slurry loss during the pouring process is prevented, which causes slurry waste. Furthermore, the gob-side tunnel retaining method of this embodiment is simple, easy to implement, and suitable for popularization and application.

[0050] Furthermore, the steel frame 4 is a semicircular frame assembled by steel bars, so that the reconstructed bearing arch is a semicircular arch. When supporting the top plate, it has higher strength and stronger ability to resist deformation of the surrounding rock, effectively preventing the occurrence of broken top plate collapse, and providing a guarantee for the construction safety of the workers.

[0051] Furthermore, in step h, according to the pressure of the gob-side tunnel section 12, if the pressure of the gob-side tunnel section 12 is too high, the template on the inner side of the arch skeleton 6 can be delayed for removal. The template on the inner side of the arch skeleton 6 serves as a temporary reinforcement support measure for the gob-side tunnel section 12. After the pressure of the gob-side tunnel section stabilizes, the template on the inner side of the arch skeleton 6 is gradually withdrawn to ensure the formation of the bearing arch and improve the supporting strength of the bearing arch.

[0052] Furthermore, the net width above the bottom of the goaf tunnel 12 is 4.3 m, and the net width of the distance between the foundation steel bars 3 on the left and right sides of the goaf tunnel 12 is 3.4 m.

[0053] Furthermore, during the forward mining process of the mining face, the roof of the remaining tunnel section is temporarily supported by a U-shaped shed.

[0054] Example 2

[0055] like Figure 3-6As shown, based on Example 1, in step e, the casting template includes an inner tunnel arch template 9 and an outer tunnel curved template 10, firstly, a plurality of inner tunnel arch templates 9 are installed on the inner side of the arch of the arch skeleton 6 with precise positioning therewith, and then a plurality of outer tunnel curved templates 10 are installed on the outer side of the arch skeleton 6 on the goaf 2 side with precise positioning therewith and adjacent to the slag retaining column 8, a first plugging plate 11 is installed at both ends of the inner tunnel arch template 9 and the outer tunnel curved template 10, and the inner tunnel arch template 9 and the outer tunnel curved template 10 and the first plugging plate 11 constitute a casting template; the inner tunnel arch template 9 adopts a first U25 steel 13 arc structure, and An arc-shaped steel plate 14 is welded to the outside of the first U25 steel 13. The in-tunnel arch formwork 9 is assembled from 4 or 6 sections. A first arc-shaped connecting plate 15 is welded at both ends of the upper part of the in-tunnel arch formwork 9. The first arc-shaped connecting plate 15 is provided with a first through hole connected to the first plugging plate 11. The out-tunnel arc formwork 10 adopts an arc-shaped structure of the second U25 steel 16. The out-tunnel arc formwork 10 is assembled from at least two sections of the second U25 steel 16. A second arc-shaped connecting plate 17 is welded at both ends of the out-tunnel arc formwork 10. The second arc-shaped connecting plate 17 is provided with a second through hole connected to the first plugging plate 11.

[0056] When carrying out this embodiment, a first U25 steel is used to make a multi-section arc structure, and then the first U25 steel of each arc structure is assembled to form an inner arch template 9, a second U25 steel is used to make a multi-section arc structure, and then the second U25 steel of the multi-section arc structure is assembled to form an outer arc template 10, the outer arc template 10 just covers half of the outer side of the arch skeleton 6 on the goaf 2 side, the inner arch template 9 is divided into multiple sections installed on the inner side of the arch skeleton 6, and the outer arc template 10 is divided into multiple sections installed on the outer side of the arc skeleton 6 on the goaf 2 side. The two ends of the inner arch template 9 are respectively welded with a first arc connecting plate 15, and the first arc connecting plate 15 extends inwardly, and the two ends of the outer arc template 10 are respectively welded with a second arc connecting plate 17, and the second arc connecting plate 17 extends outside the groove, so that the arc inner end face of the outer arc template 10 is a smooth surface, and the arc of the inner arch template 9 is smooth. The outer end face of the shape is a smooth surface. After installing a section of the empty tunnel 12 and completing the installation of a section of the template, the first plugging plate 11 is installed at both ends of the template. The specific connection method is that a first through hole is provided on the first arc-shaped connecting plate 15, and a second through hole is provided on the second arc-shaped connecting plate 17. The first plugging plate 11 between the first arc-shaped connecting plate 15 and the second arc-shaped connecting plate 17 is installed in such a way that the upper end of the first plugging plate 11 is connected to the first arc-shaped connecting plate 15 through the first through hole using at least 4 bolts, and the lower end of the first plugging plate 11 is connected to the second arc-shaped connecting plate 17 through the second through hole using at least 4 bolts. The connection method between the first arc-shaped connecting plate 15 and the first plugging plate 11 on the arch support 11 on the side where the arch support 11 is not covered by the outer arc template 10 is that the first plugging plate 11 only needs its lower end to be connected to the first arc-shaped connecting plate 15 through the first through hole using bolts to form a casting template. The first plugging plate 11 is also an arc-shaped structure.

[0057] In this embodiment, since there is no shielding structure on the side of the arch frame 6 on the goaf 2 side, slurry will flow from the arch frame 6 into the goaf 2 during pouring, causing waste of slurry and failing to form a load-bearing arch structure. Therefore, by setting the outer-tunnel curved template 10, the outer-tunnel curved template 10 is installed on one side of the arch frame 6 on the goaf 2 side, so that the load-bearing arch can be formed during the pouring process, and the outer-tunnel curved template 10 just covers half of the outer side of the arch frame 6 on the goaf 2 side, which is convenient for the installation and removal of the template, without adding extra work, and improving work efficiency. The setting of the first plugging plate 11, on the one hand, is used to block slurry during pouring, and on the other hand, is used to connect the inner-tunnel arch template 9 with the first outer-tunnel curved template 10.

[0058] Furthermore, the thickness of the steel plates used for the in-lane arch formwork 9 and the out-lane arch formwork 10 is 10 mm, and the length of each in-lane arch formwork 9 and out-lane arch formwork 10 is 0.25 m; before installing the in-lane arch formwork 9 or the out-lane arch formwork 10, every two in-lane arch formworks 9 or the out-lane arch formworks 10 are first assembled into a whole, and then moved to the arch frame 6 for installation, so that the length of each integral in-lane arch formwork 9 and out-lane arch formwork 10 is 0.5 m, and the overall installation length of the formwork is controlled within 5-10 m.

[0059] Example 3

[0060] like Figure 7 and Figure 8 As shown, based on Example 1, in step e, the casting template includes a template trolley 18 and a slurry retaining plate 19. The template trolley 18 is driven into the tunnel so that the template trolley 18 and the arch frame 6 are precisely positioned. The slurry retaining plate 19 is installed on the outer side of the arch frame 6 on the goaf 2 side, and the second plugging plates 21 are installed at both ends of the outer side of the template trolley 18. The template trolley 18 and the slurry retaining plate 19 and the second plugging plates 21 constitute a casting column template for casting support; a single column 20 is provided on the goaf 2 side adjacent to the slurry retaining plate 19.

[0061] When implementing this embodiment, a vertically upward slurry retaining plate 19 is installed on the outer side of the arched frame 6 on the side of the goaf 2, and a single column 20 is set adjacent to the slurry retaining plate 19 on the side of the goaf 2. Then the template trolley 18 is driven into the tunnel, and the template trolley 18 and the arched frame 6 are precisely positioned. Then, a second plugging plate 21 is installed at both ends of the outer side of the template trolley 18, and the length of the second plugging plate 21 close to the side of the slurry retaining plate 19 is extended to contact with the slurry retaining plate 19 to prevent leakage.

[0062] In this embodiment, the arrangement of the single column 20 provides a support site for the slurry retaining plate 19 .

[0063] Example 4

[0064] like Figure 3-9 As shown, based on Example 1, in step d, the undercover has a steel cage 22, the undercover is cast with concrete, and the upper part of the undercover along the vertical wall direction of the coal mining area 1 and along the length direction of the side of the goaf 2 has a foundation platform 14, and the lower end of the foundation steel bar 3 extends upward from the steel cage 22.

[0065] When carrying out this embodiment, a steel cage 22 is placed in the undercover, and then the foundation steel bars 3 are welded on the upper part of the steel cage 22, and then concrete is poured, and a structure is cast with the upper part of the undercover along the straight wall direction of the coal mining area 1 and the upper part of the undercover along the length direction of the goaf 2 side having a foundation platform 14. The foundation platform 14 on the coal mining area 1 side and the foundation platform 14 on the goaf 2 side cooperate with the template on the inner side of the arch frame 6 to be installed, and the template on the outer side of the arch frame 6 is installed on the side close to the goaf 2.

[0066] Furthermore, the foundation platform 14 along the vertical wall direction of the coal mining area 1 is an L-shaped structure, and the foundation platform 14 along the length direction of the side of the goaf 2 is a convex structure. The width of the foundation platform 14 with the convex structure is larger than the base platform 14 with the L-shaped structure. The transverse axis surface of the L-shaped structure and the transverse axis surface of one side of the convex structure cooperate with the template installation on the inner side of the arch frame 6, and the transverse axis surface on the other side of the convex structure is used for the template installation on the outer side of the arch frame 6. The foundation steel bars 3 near the coal mining area 1 extend in a row from the side of the steel cage 22, and the foundation steel bars 3 near the goaf 2 extend in a row from the middle of the steel cage 22.

[0067] Furthermore, the foundation steel bars 3 are welded on the ground with a steel bar size of Ф12mm. The length of each steel cage 22 is 3m, and the height of the steel cage 22 is 0.4m. A plurality of transverse and vertical steel bars are welded inside the steel cage 22 along the length direction, dividing the steel cage 22 into a plurality of small grids, and the length of each small grid is 0.5m. A supporting steel bar constituting the foundation steel bar 3 is welded every 0.2m on the steel bars along the length direction of the steel cage 22, serving as the support part of the arch skeleton 6. The width of the steel cage 22 is 0.7m, the height of the steel skeleton 4 is 1.5m, the width of the steel skeleton 4 is 0.25m, and the length of the steel skeleton 4 is 0.2m. Unlike the steel cage 22 lying in the straight wall direction of the coal mining area 1, the steel cage 22 lying along the length direction of the goaf area 2 is 1.15m wide. A plurality of transverse and vertical steel bars are welded inside the foundation steel bar 3 along the length direction, and the foundation steel bar 33 is divided into a plurality of small grids. The foundation steel bar 2 is exposed 1m above the foundation platform 14, and the height of the foundation platform 14 is 0.5m. All dimensions are strictly checked. If a deviation of more than 10mm is found, it should be adjusted in time. The size design of this embodiment enables the bearing arch of this embodiment to have a high-strength supporting capacity.

[0068] Furthermore, the foundation steel bars 2, steel cage 8 and support frame 3 can be integrally manufactured outside the tunnel.

[0069] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A method for retaining a gob-side entry by reconstructing a bearing arch by breaking the roof, characterized in that: Used for gob-side tunnel retaining support construction, including the following steps: a. Roadway expansion: The roadway between the coal mining area (1) and the goaf area (2) is expanded to form a goaf-side roadway (12) as required by the design; b. Roof maintenance: Install an end bracket (5) at the end of the mining face, and install a temporary bracket (7) on the broken roof along the side of the empty roadway (12) as a temporary support; c. Goaf retaining bar: setting up retaining bar columns (8) along the length of the goaf (2); d. Foundation construction: After the tunnel is expanded, a bottom foundation is constructed at the vertical wall position of the coal mining area (1) and along the side length direction of the goaf area (2). The upper part of the bottom foundation is pre-buried with foundation steel bars (3) that are vertically upward and arranged along the vertical wall length direction of the coal mining area (1) and the side length direction of the goaf area (2). A steel frame (4) is installed on the upper part of the foundation steel bars (3). The foundation steel bars (3) on both sides of the tunnel are connected to the same steel frame (4) to form an arch frame (6) supporting structure; e. Template installation: Install the template on the inner side of the arch frame (6) and the outer side of the arch located on the goaf (2) side in step d, and install the first plugging plate (11) at both ends of the template. The template and the first plugging plate (11) constitute a casting template; f. Pouring: After the formwork is installed, grouting is performed in the arch frame (6) by a grouting pump; g. Curing: Curing is carried out for 2-3 days after the grouting is completed; h. Demolding: After curing, the inner side of the arch frame (6) in step e and the outer side of the arch located on the goaf (2) side are removed.

2. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 1, characterized in that: In step e, the casting template includes an in-tunnel arch template (9) and an out-tunnel curved template (10), the in-tunnel arch template (9) precisely positioned with the arch skeleton (6) is installed on the inner side of the arch, the out-tunnel curved template (10) precisely positioned with the arch skeleton (6) and adjacent to the slag retaining column (8) is installed on the outer side of the arch skeleton (6) on the goaf (2), the first plugging plate (11) is installed at both ends of the in-tunnel arch template (9) and the out-tunnel curved template (10), and the in-tunnel arch template (9) and the out-tunnel curved template (10) and the first plugging plate (11) constitute a casting template.

3. A method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 2, characterized in that: The in-lane arch template (9) adopts a first U25 steel (13) arc structure, and an arc steel plate (14) is welded on the outside of the first U25 steel (13). The in-lane arch template (9) is assembled from 4 or 6 sections, and a first arc connecting plate (15) is welded at both ends of the upper part of the in-lane arch template (9). The first arc connecting plate (15) is provided with a first through hole connected to the first plug plate (11).

4. A method for retaining a gob-side entry by reconstructing a bearing arch by breaking a roof as claimed in claim 2, characterized in that: The outer lane arc template (10) adopts a second U25 steel (16) arc structure. The outer lane arc template (10) is assembled from at least two sections of the second U25 steel (16). Second arc connecting plates (17) are welded at both ends of the outer lane arc template (10). The second arc connecting plate (17) is provided with a second through hole connected to the first plug plate (11).

5. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 1, characterized in that: In step e, the casting template includes a template trolley (18) and a slurry retaining plate (19). The template trolley (18) is driven into the tunnel so that the template trolley (18) and the arch frame (6) are accurately positioned. The slurry retaining plate (19) is installed on the outer side of the arch frame (6) on the side of the goaf (2). The second plugging plate (21) is installed at both ends of the outer side of the template trolley (18). The template trolley (18), the slurry retaining plate (19) and the second plugging plate (21) constitute a casting column template for casting support.

6. A method for retaining a gob-side entry by reconstructing a bearing arch by breaking a roof as claimed in claim 5, characterized in that: A single column (20) is provided on the side of the goaf (2) and is adjacent to the slurry retaining plate (19).

7. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 1, characterized in that: In step d, the undercover has a steel cage (22), the undercover is cast with concrete, and the upper part of the undercover along the vertical wall direction of the coal mining area (1) and along the side length direction of the goaf area (2) has a foundation platform (14), and the lower end of the foundation steel bar (3) extends upward from the steel cage (22).

8. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 7, characterized in that: The foundation platform (14) along the vertical wall direction of the coal mining area (1) is in an L-shaped structure, and the foundation platform (14) along the side length direction of the goaf area (2) is in a convex-shaped structure.

9. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 1, characterized in that: The steel frame (4) is a semicircular frame assembled from steel bars.

10. The method for reconstructing a bearing arch gob-side entry by breaking the roof as claimed in claim 1, characterized in that: In step h, according to the pressure of the section along the gob tunnel (12), the template on the inner side of the arch frame (6) can be removed later, and the template on the inner side of the arch frame (6) serves as a temporary reinforcement support.

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