Wall column combined support control gob-side roadway floor heave construction process

Abstract

The invention provides a wall-column combined support control gob-side roadway floor heave construction process, and belongs to the technical field of mining construction processes. The method comprises the steps that (1) a roadway is tunneled, meanwhile, a roadway coal pillar side bottom plate is subjected to groove milling, and a reserved groove is formed; (2) the configured reinforcement cage is hoisted into the reserved groove; (3) wet spraying of quick-setting concrete is carried out, and underground wall construction is completed; and (4) after the strength of the underground wall meets the supporting requirement, wall-column combined supporting gob-side entry retaining floor heave control is completed. The original transmission path is cut off through the self-strength and anchoring effect of the milling groove building wall, the soft bottom plate is prevented from extruding and flowing, meanwhile, the supporting strength of the coal pillar side is enhanced through wall column combination, the vault effect is weakened, the method can adapt to the high-stress surrounding rock state, associated damage to the surrounding rock can be avoided, and the heaving floor problem can be relieved.

Description

Technical Field

[0001] The invention relates to the technical field of mining construction technology, and in particular to a construction technology for controlling floor heave in goaf-side tunnels by using wall-column combined support. Background Art

[0002] Roof cutting and pressure relief along the goaf has been widely promoted and applied. It is one of the important ways to improve coal recovery rate, ease the tension of mining and excavation connection, and extend the service life of mines. It has been successful in thin coal seams and medium-thick coal seams. However, according to incomplete statistics, relevant roadway retention projects and literature show that the amount of roadway floor heave accounts for more than 70% of the roof and floor movement. The control of roadway floor heave deformation is the main factor limiting the promotion of roof cutting and roadway retention in soft rock floor geological conditions.

[0003] Due to the structural characteristics of the 110 construction method, the supporting stress of the solid coal wall and coal pillar on the bottom rock layer shows obvious asymmetry. The stress of the overlying rock layer is transmitted to the bottom plate through the solid coal wall and coal pillar, causing the solid coal wall bottom rock layer to deform and break when affected by the lateral high supporting stress, and move laterally to the tunnel and goaf. Especially when encountering soft rock bottom geological conditions such as mudstone and sandy mudstone, after the lane is retained, due to the impact of mining and the release of coal mining stress, the bottom drum of the lane is serious. How to control the bottom drum of the soft rock bottom lane is an engineering problem that needs to be solved urgently.

[0004] Existing measures for the prevention and treatment of floor heave can be divided into bottom lifting and pressure relief. Tunnel bottom lifting is a commonly used treatment method, but in the face of high-stress and deep-buried tunnels, the bottom lifting method for the treatment of floor heave will not only increase the work process of tunnel clearing, but also seriously threaten the overall stability of the tunnel; although the groove cutting pressure relief method is generally applicable, it is difficult to calculate the groove size of this method, and due to the increase in mining height, the displacement of the tunnel side will also increase accordingly. In view of the above engineering problems, it is urgent to propose a floor heave treatment method that can adapt to the high-stress surrounding rock state and avoid the associated damage of the surrounding rock. Summary of the invention

[0005] In view of this, in order to solve the technical problem of bottom drum in the soft rock floor, the present invention provides a construction process for controlling the bottom drum of the tunnel along the goaf by using a wall-column combined support. The strength of the milling wall and the anchoring effect are used to cut off the original transmission path to prevent the squeezing flow of the weak floor. At the same time, the wall-column combination is used to enhance the support strength of the coal pillar and weaken the vault effect. It can adapt to the high-stress surrounding rock state, avoid the associated damage of the surrounding rock, and alleviate the bottom drum problem.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A construction process for controlling floor heave of a roadway along a goaf by using a wall-column combined support method comprises the following steps:

[0008] Step (1), while excavating the tunnel, milling grooves on the side bottom plate of the tunnel coal pillar to form a reserved groove;

[0009] Step (2), hoisting the configured steel cage into the reserved slot;

[0010] Step (3), wet spraying quick-setting concrete to complete the underground wall construction;

[0011] Step (4): After the underground wall strength reaches the support requirements, complete the wall-column joint support and bottom heave control along the gob-retained lane.

[0012] Preferably, in step (4), the wall-column joint support comprises the following steps:

[0013] Step (41), arranging I-beams on the top of the underground wall along the lane, arranging single columns on the I-beams, and arranging π-shaped steel above the single columns;

[0014] Step (42), raising the monomer column;

[0015] Step (43), after the working face system is formed, the working face is always ahead to carry out constant resistance anchor cable reinforcement support on the tunnel roof;

[0016] Step (44), after the constant resistance anchor cable support is completed, the advanced working face is constructed with concentrated energy blasting drilling to form a pre-cracked cutting surface in the side roof of the goaf area of ​​the tunnel;

[0017] Step (45), after the coal seam of the working face is mined, U-shaped steel is arranged close to the blasting top cutting line to carry out gangue support and complete the tunnel control;

[0018] Step (46), using unit supports for temporary support in the dynamic pressure influence area to further limit the amount of floor heave and the amount of movement of the two sides of the tunnel;

[0019] Step (47), after the lane is stable, withdraw the unit support; when the next mining face is mined, withdraw the π-shaped steel, I-beam and single column as it is mined, so that the wall-column combined support and bottom heave control of the lane retained along the gob are completed.

[0020] Preferably, in step (45), the U-shaped steel comprises an upper U-shaped steel, a lower U-shaped steel and a clamping cable;

[0021] Weld round steel to the top of the upper U-shaped steel, drill holes in the top plate, insert the round steel into the holes, limit displacement, dig shallow grooves at the corresponding positions on the bottom plate, insert steel plates, and place the lower U-shaped steel. After configuration is completed, use cable clamps to fix the upper and lower U-shaped steels.

[0022] Preferably, in step (2), the steel cage is a prefabricated steel cage assembly.

[0023] Preferably, the prefabrication method of the prefabricated steel cage assembly is as follows:

[0024] Step (21), bend the single-side end of the quick-installed structural reinforcement into a "J" shape, bend the double-side ends of the reinforcing reinforcement in the same direction into a hook "C" shape, and weld them on the ground according to the designed reinforcement spacing to form a prefabricated steel mesh;

[0025] Step (22), hook the reserved connection hook of the quick-installed structural reinforcement to the end load-bearing main reinforcement of the front section of the steel mesh according to the required segment length, hook the quick-installed structural reinforcement to the single load-bearing main reinforcement at the end and fix it with wire; hook the reinforcing reinforcement in a plum blossom shape, and encrypt it at the edge of the wall to form a steel cage for the underground wall.

[0026] Preferably, in step (21), the single-side end of the quick-installed structural reinforcement is bent 180° to form a "J" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight part after the hook is bent is not less than three times the diameter of the steel bar; the double-sided ends of the reinforcement tie bar are bent 180° in the same direction to form a "C" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight part after the hook is bent is not less than three times the diameter of the steel bar.

[0027] Preferably, in step (41), the lengths of the π-shaped steel and the I-shaped steel are both 3 m, the spacing between the I-shaped steels is 20 cm, and the individual columns are arranged at a column spacing of 80 cm starting from 30 cm from the end of each section of the I-shaped steel. The arrangement method of the π-shaped steel is the same as that of the I-shaped steel.

[0028] Preferably, in step (41), the monomer column is a large diameter monomer column of W-200 / 125.

[0029] Preferably, in step (43), the tunnel roof is always reinforced with constant resistance anchor cables 200 m ahead of the working face;

[0030] In step (44), after the constant resistance anchor cable support is completed, energy blasting drilling is carried out 100m ahead of the working face.

[0031] Preferably, in step (1), when the mining height of the tunnel is less than 4 m, the depth of the milling groove is equal to the mining height; when the mining height of the tunnel exceeds 4 m, the depth of the milling groove is 4 m.

[0032] The present invention mills grooves on the side bottom plate of the tunnel coal pillar while digging the tunnel, fills in prefabricated steel cages for assembly and wet spraying to quickly build underground walls. After the strength of the underground wall reaches the support requirements, the wall-column joint support is completed to control the floor drum along the goaf-retained tunnel. By arranging anchors (constant resistance anchor cables) to reinforce the tunnel, the top is cut to prepare for mining, and U-shaped steel flexible pressure-resisting gangue support is completed during the mining stage to achieve the purpose of preventing floor drums and solve the problems of difficult control and treatment of floor drum accidents in existing goaf-retained tunnel technologies. Compared with the existing technology, it has the following beneficial effects:

[0033] The present invention utilizes the strength of the milling groove wall and the anchoring effect to cut off the original transmission path, prevent the weak bottom plate from squeezing and flowing, and simultaneously utilizes the wall column to enhance the support strength of the coal pillar side and weaken the vault effect. It can adapt to the high stress surrounding rock state, avoid the associated damage of the surrounding rock, and alleviate the bottom drum problem.

[0034] The present invention can prevent the occurrence of associated damage to the surrounding rock, avoid secondary tunnel clearing work of cutting the side and bottom, and improve the mining efficiency.

[0035] The present invention uses prefabricated components as main assembly parts for construction according to the design, can flexibly control the length of the wall, is easy to pile and spray concrete, reaches the target strength quickly, and can quickly form and complete the construction.

[0036] Other technical effects of the present invention will be described in the following specific implementation method section. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram for mining layout;

[0038] Figure 2 This is a schematic diagram of the underground wall reinforcement cage structure;

[0039] Figure 3 It is a structural schematic diagram of a prefabricated steel mesh;

[0040] Figure 4 It is a schematic diagram of the structure of the reinforcement reinforcement;

[0041] Figure 5 It is the structural diagram of the main reinforcement;

[0042] Figure 6 This is a schematic diagram of the steps for joint support of walls and columns;

[0043] Figure 7 It is a schematic diagram of the steps of top cutting and pressure relief;

[0044] Figure 8 This is a schematic diagram of the lane retention process;

[0045] In the figure, 1, tunnel; 2, milling groove; 3, mining wall; 4, coal pillar wall; 5, underground wall; 6, prefabricated steel mesh; 7, reinforcing tie rod; 8, load-bearing main reinforcement; 9, steel cage; 10, roof; 11, constant resistance anchor cable; 12, shaped energy blasting drilling hole; 13, gangue; 14, U-shaped steel; 141, U-shaped steel upper section; 142, U-shaped steel lower section; 143, cable clamp; 15, unit bracket; 16, π-shaped steel; 17, I-beam; 18, single column. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] like Figure 1-8 As shown, the present invention provides a construction process for controlling the bottom drum of the tunnel 1 along the goaf by using a wall-column joint support. The side bottom plate of the tunnel 1 coal pillar 4 is milled 2 while the tunnel is being excavated, and prefabricated steel bars are filled in for assembly and wet spraying to quickly build an underground wall 5. After the strength of the underground wall 5 reaches the support requirements, the wall-column joint support is completed, anchors are arranged to reinforce the tunnel 1, the top is cut to prepare for mining, and U-shaped steel 14 is completed in the mining stage to flexibly support the gangue, thereby achieving the purpose of preventing the bottom drum and solving the technical problem of the existing soft rock bottom plate retaining the bottom drum of the tunnel. The technical solution of the present invention is as follows:

[0050] Step (1), while excavating the tunnel 1, a groove 2 is milled on the side floor of the coal pillar of the tunnel 1 (near the mining side 3) to form a reserved groove. Specifically, it can be:

[0051] On the premise of meeting the requirements of safe and efficient milling groove 2 underground, the milling groove 2 construction equipment is used to mill groove 2 on the side bottom plate of the coal pillar of tunnel 1 while excavating the tunnel 1, and 20 to 30 cm of equipment operation space is reserved. When the mining height of tunnel 1 is less than 4m, the depth of milling groove 2 is equal to the mining height. When the mining height of tunnel 1 exceeds 4m, the depth of milling groove 2 is 4m.

[0052] Step (2), hoist the configured steel cage 9 into the reserved groove. Among them, the construction industry specification "GB50010-2010" is used as the calculation basis. According to the calculation of the bending and compression of the wall, the bearing capacity of the wall is much greater than the surrounding rock stress, and the structural steel bars within the specification are used to prepare the steel cage 9. The steel cage 9 is preferably a prefabricated prefabricated steel cage 9 assembly, which is preferably composed of prefabricated steel mesh 6, reinforcing bars 7 and main force bars 8 assembled from quick-install structural bars (quick-install structural bars refer to steel bars arranged in reinforced concrete structures to meet structural requirements. The layout of such steel bars is carried out in accordance with the mandatory requirements of the national building structure design specifications and does not require recalculation by designers. The main function of quick-install structural bars is to solve some factors that are difficult to measure and ensure the stability and safety of the structure).

[0053] In the present invention, the prefabrication method of the prefabricated steel cage 9 assembly is as follows:

[0054] Step (21), bend the single-side end of the quick-installed structural reinforcement into a "J" shape, bend the double-side ends of the reinforcing tie bar 7 in the same direction into a hook "C" shape, and weld them on the ground to form a prefabricated steel mesh 6 according to the designed reinforcement spacing; level the site as needed, and transport the prefabricated steel mesh 6 and the reinforcing tie bar 7 to the vicinity of the construction site. Weld them on the ground to form a prefabricated steel mesh 6 according to the designed reinforcement spacing. Pack the steel bar materials in groups for deployment. Solve the problem of difficulty in preparing the underground wall 5 steel cage 9 and difficulty in transporting prefabricated materials.

[0055] Step (22), hook the reserved connecting hook of the quick-installed structural reinforcement onto the end force-bearing main reinforcement 8 of the front section steel mesh according to the required segment length, hook the quick-installed structural reinforcement onto the single force-bearing main reinforcement 8 at the end and fix it with wire; hook the reinforcing tie bars 7 in a plum blossom shape, and encrypt them at the edge of the wall (preferably 50 cm) to form a steel cage 9 for the underground wall 5. If the position of the tie bars interferes with the prefabricated steel mesh 6, the position of the tie bars should be appropriately adjusted.

[0056] Among them, in step (21), the single-side end of the quick-installed structural reinforcement is bent 180° to form a "J" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight part after the hook is bent is not less than three times the diameter of the steel bar; the double-sided ends of the reinforcing tie bar 7 are bent 180° in the same direction to form a "C" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight part after the hook is bent is not less than three times the diameter of the steel bar.

[0057] Step (3) is to spray quick-setting concrete to complete the construction of the underground wall 5. Specifically, it can be:

[0058] The configured steel cage 9 is hoisted into the reserved groove of the bottom plate; quick-setting wet spraying concrete is prepared and sprayed from the gaps of the steel cage 9 along the direction of the tunnel 1; vibration and maintenance are performed, and the construction of a section of the underground wall 5 is completed when the underground wall 5 reaches the target strength.

[0059] Step (4): After the strength of the underground wall 5 reaches the support requirement, the bottom heave control of the gob-retained lane along the wall-column joint support is completed.

[0060] In the present invention, in step (4), the wall-column joint support comprises the following steps:

[0061] Step (41), transporting π-shaped steel 16, I-shaped steel 17 and large diameter single column 18 to the vicinity of the construction site. Arrange I-shaped steel 17 on the top of underground wall 5 along the lane, arrange single column 18 on I-shaped steel 17, and arrange π-shaped steel 16 above single column 18.

[0062] In step (41), the lengths of the π-shaped steel 16 and the I-shaped steel 17 are both 3 m, and the arrangement spacing of the I-shaped steel 17 is 20 cm. According to the "one bottom beam and four columns" method, the single column 18 is arranged at a column spacing of 80 cm starting from 30 cm from the end of each section of the I-shaped steel 17. The arrangement method of the π-shaped steel 16 is the same as the arrangement method of the I-shaped steel 17.

[0063] In the present invention, in step (41), the monomer column 18 is a large diameter monomer column 18 of W-200 / 125.

[0064] Among them, the single column 18 can preferably be a single hydraulic support.

[0065] Step (42), raising the single column 18, increasing the working resistance, and achieving the supporting strength.

[0066] Step (43), after the working face system is formed, the working face is always ahead of the other working face to reinforce the top plate 10 of the tunnel 1 with the constant resistance anchor cable 11. Specifically, it can be:

[0067] After the working face system is formed, the top plate 10 of the tunnel 1 is always reinforced and supported by constant resistance anchor cables 11 200m ahead of the working face.

[0068] Step (44), after the constant resistance anchor cable 11 is supported, the energy blasting drilling hole 12 is constructed on the advanced working face to form a pre-cracked cutting surface in the side roof 10 of the goaf area of ​​the tunnel 1. Specifically, it can be:

[0069] After the constant resistance anchor cable 11 support is completed, the geological conditions are analyzed, and the energy blasting drilling hole 12 is designed and constructed 100m ahead of the working face to form a pre-crack cutting surface in the side roof 10 of the goaf area of ​​tunnel 1.

[0070] Step (45), after the coal seam of the working face is mined, U-shaped steel 14 (preferably at 40 cm intervals) is arranged close to the blasting top cutting line to provide support for the gangue (gangue 13) and complete the control of the tunnel 1.

[0071] In step (45), the U-shaped steel 14 includes an upper U-shaped steel 141, a lower U-shaped steel and a clamping cable 143; the arrangement of the U-shaped steel 14 can be carried out in the following manner:

[0072] Round steel is welded to the top of the upper U-shaped steel 141, a hole is drilled in the top plate 10, the round steel is inserted into the drilled hole to limit the displacement, a shallow groove is dug into the bottom plate at the corresponding position, a steel plate is built in, and the lower U-shaped steel 142 is placed. After the configuration is completed, the upper U-shaped steel 141 and the lower U-shaped steel 142 are fixed using the cable 143.

[0073] Step (46), in the dynamic pressure influence area (300m behind the mining face), temporary support is provided by using unit supports 15 to further limit the bottom heave of tunnel 1 and the displacement of the two sides.

[0074] Step (47), after the lane is stable, withdraw the unit support 15; when the next mining face is mined, withdraw the π-shaped steel 16, I-beam 17 and single column 18 as the mining proceeds. At this point, the wall-column combined support and bottom heave control along the gob-retained lane are completed.

[0075] The above are only preferred specific implementations of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A construction process for controlling floor heave in goaf-side tunnels by using wall-column joint support, characterized in that: The steps include: Step (1), while excavating the tunnel, milling grooves on the side bottom plate of the tunnel coal pillar to form a reserved groove; Step (2), hoisting the configured steel cage into the reserved slot; Step (3), wet spraying quick-setting concrete to complete the underground wall construction; Step (4): After the underground wall strength reaches the support requirements, complete the wall-column joint support and gob-retained tunnel bottom heave control.

2. A construction process for controlling floor heave of goaf-side tunnel by wall-column combined support according to claim 1, characterized in that: In step (4), the wall-column joint support includes the following steps: Step (41), arranging I-beams on the top of the underground wall along the lane, arranging single columns on the I-beams, and arranging π-shaped steels above the single columns; Step (42), raising the monomer column; Step (43), after the working face system is formed, the working face is always ahead to carry out constant resistance anchor cable reinforcement support on the tunnel roof; Step (44), after the constant resistance anchor cable support is completed, the advanced working face is constructed with concentrated energy blasting drilling to form a pre-cracked cutting surface in the side roof of the goaf area of ​​the tunnel; Step (45), after the coal seam of the working face is mined, U-shaped steel is arranged close to the blasting top cutting line to carry out gangue support and complete the tunnel control; Step (46), using unit supports for temporary support in the dynamic pressure influence area to further limit the amount of floor heave and the amount of movement of the two sides of the tunnel; Step (47), after the lane is stable, withdraw the unit support; when the next mining face is mined, withdraw the π-shaped steel, I-beam and single column as it is mined, so that the wall-column combined support and bottom heave control of the lane retained along the gob are completed.

3. A construction process for controlling floor heave of gob-side tunnel by wall-column combined support according to claim 2, characterized in that: In step (45), the U-shaped steel includes an upper U-shaped steel, a lower U-shaped steel and a clamping cable; Weld round steel to the top of the upper U-shaped steel, drill holes in the top plate, insert the round steel into the holes, limit displacement, dig shallow grooves at the corresponding positions on the bottom plate, insert steel plates, and place the lower U-shaped steel. After configuration is completed, use cable clamps to fix the upper and lower U-shaped steels.

4. The construction process for controlling floor heave of gob-side tunnel by wall-column combined support according to claim 1 is characterized in that: In step (2), the steel cage is a prefabricated steel cage assembly.

5. A construction process for controlling floor heave of goaf-side tunnel by wall-column combined support according to claim 4, characterized in that: The prefabrication method of the prefabricated steel cage assembly is as follows: Step (21), bend the single-side end of the quick-installed structural reinforcement into a "J" shape, bend the double-side ends of the reinforcing reinforcement in the same direction into a hook "C" shape, and weld them on the ground according to the designed reinforcement spacing to form a prefabricated steel mesh; Step (22), hook the reserved connection hook of the quick-installed structural reinforcement to the end load-bearing main reinforcement of the front section of the steel mesh according to the required segment length, hook the quick-installed structural reinforcement to the single load-bearing main reinforcement at the end and fix it with wire; hook the reinforcing reinforcement in a plum blossom shape, and encrypt it at the edge of the wall to form a steel cage for the underground wall.

6. A construction process for controlling floor heave of gob-side tunnels by wall-column combined support according to claim 5, characterized in that: In step (21), the single-side end of the quick-installed structural reinforcement is bent 180° to form a "J" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight portion after the hook is bent is not less than three times the diameter of the steel bar; the double-side ends of the reinforcement tie bar are bent 180° in the same direction to form a "C" shape, the inner diameter of the arc is not less than 2.5 times the diameter of the steel bar, and the length of the straight portion after the hook is bent is not less than three times the diameter of the steel bar.

7. The construction process for controlling floor heave of gob-side tunnel by wall-column combined support according to claim 2 is characterized in that: In step (41), the lengths of the π-shaped steel and the I-shaped steel are both 3 m, the spacing between the I-shaped steels is 20 cm, and the individual columns are arranged at a column spacing of 80 cm starting from 30 cm from the end of each section of the I-shaped steel. The arrangement method of the π-shaped steel is the same as that of the I-shaped steel.

8. The construction process for controlling floor heave of gob-side tunnel by wall-column combined support according to claim 2 is characterized in that: In step (41), the monomer column is a large diameter monomer column of W-200 / 125.

9. The construction process for controlling floor heave of gob-side tunnel by wall-column combined support according to claim 2 is characterized in that: In step (43), the tunnel roof is always reinforced with constant resistance anchor cables 200 m ahead of the working face; In step (44), after the constant resistance anchor cable support is completed, energy blasting drilling is carried out 100m ahead of the working face.

10. A construction process for controlling floor heave of goaf-side tunnel by wall-column combined support according to any one of claims 1 to 9, characterized in that: In step (1), when the mining height of the tunnel is less than 4m, the milling groove depth is equal to the mining height; when the mining height of the tunnel exceeds 4m, the milling groove depth is 4m.

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