Tunnel overbreak fast backfill and high efficiency construction device and method of spraying concrete

Abstract

This invention relates to the field of tunnel construction technology, specifically disclosing a high-efficiency construction device and method for rapid backfilling and shotcrete application in tunnel over-excavation. The device includes: steel supports, an outer edge formwork support system for the steel supports, an inner edge formwork support system for the steel supports, and hollow grouting anchors. A steel support connecting plate is provided between two adjacent steel supports. The hollow grouting anchors are installed at the over-excavated cavities and are used to inject grout into the over-excavated cavities and the rapid backfilling area of ​​the tunnel over-excavation. In handling over-excavation backfilling, the outer edge formwork is fixed to the outer surface of the steel supports, which can effectively control the shotcrete thickness to meet design requirements, while improving the efficiency of shotcrete construction and accelerating the construction progress. After the shotcrete has formed, the pre-reserved hollow grouting anchors are used to inject grout into the over-excavated cavities for reinforcement. Using the outer edge formwork and the shotcrete layer, no additional formwork support structure is required, resulting in low cost and extremely fast, efficient, and convenient construction.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a high-efficiency construction device and method for rapid backfilling and shotcrete application in tunnel over-excavation. Background Technology

[0002] Over-excavation has many adverse effects on tunnels, such as significantly increasing the thickness of the shotcrete layer, increasing construction time and costs. Moreover, due to the loose and non-dense nature of backfill materials such as rubble concrete, it may have a continuous adverse effect on the structure under the pressure of the surrounding rock. In particular, improper handling of over-excavation in the arch can lead to lining damage and detachment in the later stage, causing major operational safety accidents.

[0003] However, in the field of mountain tunnels, the drill-and-blast method is usually used for excavation, which has a very high probability of over-excavation, especially in loose strata of Class IV or higher surrounding rock. The over-excavation value is difficult to control precisely, and the over-excavation range is also difficult to control. It may be much greater than 25cm, and may even exceed 1m.

[0004] Over-excavation is a common occurrence during tunnel construction, and all over-excavated portions must be backfilled with the same grade of concrete. Standards generally allow for backfilling with the same grade of shotcrete for over-excavation. For over-excavation exceeding the standard allowance, secondary lining with the same grade of concrete should be used for backfilling. For uniform over-excavation with steel frames, shotcrete backfilling should be used, or the thickness of the secondary lining concrete should be increased. For localized over-excavation, where the over-excavation does not exceed 20cm, shotcrete backfilling should be used. For sidewall over-excavation, concrete or rubble concrete can be used for backfilling.

[0005] If all the over-excavated cavities are filled with shotcrete, the shotcrete construction time will increase several times, disrupting the construction schedule. This can easily lead to shoddy workmanship, with only the surface of the initial tunnel support being filled with shotcrete, while the cavities left by the over-excavation are left untreated. This not only results in poor structural stress but also leaves serious safety hazards. The rock behind the initial tunnel support will continue to weather and detach, eventually causing rock collapse, generating enormous impact forces that damage the structure, and even leading to the lining being breached by detached rock, causing train accidents.

[0006] If concrete or rubble concrete is used for backfilling, the backfilling speed can be accelerated. However, the backfilled rubble has many gaps, is loose and not dense, and has poor integrity. As the pressure of the surrounding rock is further released, the rubble is prone to cracking and breaking under the pressure of the surrounding rock, which has an adverse effect on the lining structure.

[0007] Furthermore, during the initial support of tunnels using shotcrete, the lack of formwork results in a large rebound rate of the shotcrete, with losses reaching up to 30%. The rebound loss rate of dry shotcrete equipment is even higher. This not only reduces the construction speed and efficiency of shotcrete but also significantly increases the cost of initial support for tunnels.

[0008] Therefore, there is an urgent need for a high-efficiency construction device for tunnel over-excavation rapid backfilling and shotcrete, which can accelerate the construction speed and quality of over-excavation backfilling, while also speeding up the construction speed of conventional initial support, reducing rebound loss, lowering construction costs, and improving efficiency. Summary of the Invention

[0009] The purpose of this invention is to provide a high-efficiency construction device and method for rapid backfilling and shotcreting of tunnel over-excavation, in order to solve the problems existing in the prior art.

[0010] To achieve the above objectives, the present invention provides a high-efficiency construction device for rapid backfilling and shotcrete application in tunnel over-excavation, comprising: Steel supports, with steel support connecting pads provided between two adjacent steel supports; A steel support outer edge formwork support system is fixedly installed on the outside of the steel support and located outside the steel reinforcement mesh in the initial support. The steel support outer edge formwork support system is used to seal over-excavated voids in the tunnel. The inner edge formwork support system of the steel support is fixedly installed on the inner side of the steel support and located on the inner side of the steel mesh in the initial support. The area between the outer edge formwork support system of the steel support and the inner edge formwork support system of the steel support is the tunnel over-excavation rapid backfill area. A hollow grouting anchor is installed at the over-excavated cavity, and the hollow grouting anchor is used to inject grout into the over-excavated cavity and the rapid backfilling area of ​​the tunnel.

[0011] Preferably, the outer edge formwork support system of the steel support includes an outer edge steel plate, which is fixedly installed on the steel support connecting pad and / or the outer edge support reinforcement of the steel support; the two sides of the outer edge steel plate are roughened.

[0012] Preferably, the outer edge steel plate includes a first cuboid steel plate, a first stepped steel plate, and a first hole-covering body; the first cuboid steel plate is provided with a first anchor bolt reserved hole, and the first hole-covering body is adapted to the first anchor bolt reserved hole; two adjacent first cuboid steel plates are overlapped by the first stepped steel plate; the two sides of the first cuboid steel plate are roughened.

[0013] Preferably, the length of the outer edge support rib is 4cm-5cm.

[0014] Preferably, the two ends of the first cuboid steel plate are respectively erected on two adjacent steel supports, and the length of the first cuboid steel plate erected on each steel support is half the width of the steel support.

[0015] Preferably, the inner edge formwork support system of the steel support includes an inner edge steel plate and end sealing strips. The inner edge steel plate is fixedly installed on the steel support connecting pad and / or the inner edge support reinforcement of the steel support. The end sealing strips are arranged at both ends of the inner edge steel plate along the excavation direction.

[0016] Preferably, the inner edge steel plate includes a second cuboid steel plate, a second stepped steel plate, and a second hole-covering body; the second cuboid steel plate is provided with bolt pre-drilled holes and second anchor bolt pre-drilled holes, and the second hole-covering body is adapted to the second anchor bolt pre-drilled holes; the second cuboid steel plate is fixedly connected to the inner edge frame reinforcement by bolts; two adjacent second cuboid steel plates are overlapped by the second stepped steel plate.

[0017] Preferably, the hollow grouting anchor rod includes a rod body, one end of which is provided with a tail grouting hole, and the other end of which is equipped with an anchor plate and a sealing valve. The end of the rod body near the anchor plate is provided with a rod body grouting hole, and the rod body is connected to the concrete spraying pipe of the grouting equipment through the sealing valve.

[0018] Preferably, a pressure sensor is installed inside the over-excavated cavity, and the pressure sensor is respectively installed at the deepest and highest points of the over-excavated cavity; the pressure data of the pressure sensor is led out to the initial support through the sensor data line.

[0019] A method for rapid backfilling and shotcrete construction of tunnel over-excavation, using the aforementioned efficient construction device for rapid backfilling and shotcrete construction of tunnel over-excavation, includes the following steps: S1. Rapid backfilling of tunnel over-excavation; S11. Pre-install pressure sensors at the deepest point and the top of the over-excavated cavity, and lead out the sensor data lines to the initial support. S12. Install steel supports. After the steel supports are in place, install the outer edge support reinforcement. S13. Install anchor bolt holes in the surrounding rock of the tunnel; S14. Install the outer edge template; S15. Drive the hollow grouting anchor into the anchor drill hole and pass the hollow grouting anchor through the reserved hole reserved in the outer edge template, and close the sealing valve; S16. Shotcrete construction: Shotcrete is applied to the outer edge of the steel plate until it covers the steel support and the protective layer and initial support thickness meet the requirements. S17. Grouting operation: After the initial support shotcrete operation is completed and reaches 70% strength, grout is injected into the over-excavated cavity through hollow grouting anchors until the pressure sensor shows that the grouting cavity has been backfilled and compacted. Then, grouting is stopped and the sealing valve is closed. S18. When the strength of the grout reaches 70% of the design strength, cut off the part of the hollow grouting anchor that extends out of the initial support surface to ensure that the initial support surface is flat and aesthetically pleasing. S2, rapid tunnel construction; S21. Install the inner edge template; S22. Set anchor bolt holes in the surrounding rock of the tunnel, avoiding the anchor bolt hole locations in step S13; S23. Drive the hollow grouting anchor into the anchor hole of step S22, and make the hollow grouting anchor pass through the reserved hole reserved in the inner edge template, and close the sealing valve. S24. Spray a thin layer of concrete onto the inner edge formwork surface until it covers the entire inner edge formwork. S25. Grout the construction section of the shotcrete in step S24 through the grouting hole of the hollow grouting anchor rod. S26. After the grout has solidified, remove the inner edge template, grind it, and repeat steps S22-S25 above for continuous construction.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects: 1. When dealing with over-excavation backfilling, the device is a consumable and cannot be reused. It is installed on the side of the initial support close to the surrounding rock. At this time, the outer edge template of the device is fixed to the outer surface of the steel support and remains permanently in the tunnel as part of the initial support. It can effectively control the thickness of the shotcrete to meet the design requirements, while improving the construction efficiency of shotcrete and speeding up the construction progress. After the shotcrete is formed, the pre-reserved hollow grouting anchor rods are used to inject grout into the over-excavated cavity for reinforcement. At this time, the outer edge template and the shotcrete layer will act as a "template" without the need for an additional template support structure. It is low in cost and the construction is very fast, efficient and convenient.

[0021] 2. Hollow grouting anchors are used at the over-excavated cavities. When grouting into the over-excavated cavities, it is necessary to ensure the grouting pressure to make the internal backfill material dense. Therefore, pressure monitoring sensors are installed at the highest point and deepest part of the over-excavated cavities to dynamically feed back the filling density of the over-excavated cavities during the construction process, ensuring the quality of over-excavation backfilling and eliminating potential safety hazards.

[0022] 3. During the initial support construction, the inner edge template installed on the inner surface of the initial support near the tunnel clearance can act as a movable temporary support. This not only makes the initial support surface smoother and more aesthetically pleasing, but also reduces the rebound loss of shotcrete, speeds up the shotcrete construction, and achieves cost reduction and efficiency improvement.

[0023] 4. The inner edge template of the present invention can be removed and polished after a certain stage is completed, and then proceed to the next stage. It can be used not only for side walls and arches, but also for the construction of the initial support of the invert arch, and has wide applicability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the tunnel over-excavation rapid backfilling and shotcrete high-efficiency construction device of the present invention; Figure 2 This is a structural schematic diagram from another perspective of the tunnel over-excavation rapid backfilling and shotcrete high-efficiency construction device of the present invention; Figures 3-11 This is a schematic diagram of the construction sequence of the tunnel over-excavation rapid backfilling and shotcrete high-efficiency construction method in Embodiment 3 of the present invention; Figure 12 This is a schematic diagram of the inner edge steel plate of the present invention; Figure 13 This is a schematic diagram of the outer steel plate of the present invention; Figure 14 This is a rear view of the inner edge steel plate of the present invention; Figure 15 These are component drawings of the second cuboid steel plate, the second stepped steel plate, and the second hole-shielding body of the present invention. Figure 16 This is a schematic diagram of the hollow grouting anchor rod of the present invention; Figure 17 This is a connection diagram of the pressure sensor of the present invention; In the diagram: 1. Outer steel plate; 101. First anchor bolt reserved hole; 12. First cuboid steel plate; 13. First stepped steel plate; 14. First hole-covering body; 2. Inner steel plate; 21. Bolt; 22. Second cuboid steel plate; 23. Second stepped steel plate; 24. End sealing strip; 25. Second anchor bolt reserved hole; 26. Bolt reserved hole; 27. Second hole-covering body; 3. Over-excavated cavity; 4. Steel support; 5. Steel support connecting pad; 6. Outer edge support reinforcement; 7. Hollow grouting anchor bolt; 71. Anchor plate; 72. Rod body; 73. Rod body grouting hole; 74. Tail end grouting hole; 75. Control valve; 8. Pressure sensor; 81. Sensor data cable; 9. Initial support for the inner surface of the tunnel; 10. Inner edge support reinforcement; 11. Concrete spraying pipe. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1 This invention provides a high-efficiency construction device for rapid backfilling and shotcrete application in tunnel over-excavation, comprising: Steel support 4, with a steel support connecting plate 5 installed between two adjacent steel supports 4; The steel support outer edge formwork support system is fixedly installed on the outside of the steel support 4 and located on the outside of the steel mesh in the initial support. The steel support outer edge formwork support system is used to seal the over-excavated void 3 in the tunnel. The inner edge formwork support system of the steel support is fixedly set inside the steel support 4 and located inside the steel mesh in the initial support. The area between the outer edge formwork support system of the steel support and the inner edge formwork support system of the steel support is the tunnel over-excavation rapid backfill area. Hollow grouting anchor 7 is installed at the over-excavated cavity 3. The hollow grouting anchor 7 is used to grout the over-excavated cavity 3 and the rapid backfilling area of ​​the over-excavated tunnel.

[0028] The scheme is further optimized. The steel support outer edge formwork support system includes an outer edge steel plate 1, which is fixedly installed on the steel support connecting pad 5 and / or the outer edge support reinforcement 6 of the steel support 4; the two sides of the outer edge steel plate 1 are roughened.

[0029] Further optimization of the scheme: the outer steel plate 1 includes a first cuboid steel plate 12, a first stepped steel plate 13, and a first hole-covering body 14; the first cuboid steel plate 12 is provided with a first anchor bolt reserved hole 101, and the first hole-covering body 14 is adapted to the first anchor bolt reserved hole 101; two adjacent first cuboid steel plates 12 are overlapped by the first stepped steel plate 13; the two sides of the first cuboid steel plate 12 are roughened.

[0030] To further optimize the scheme and ensure that the steel support 4 has sufficient protective layer thickness in the initial support, the length of the outer edge support reinforcement 6 is 4cm-5cm.

[0031] In a further optimized design, the two ends of the first rectangular steel plate 12 are respectively erected on two adjacent steel supports 4, and the length of the first rectangular steel plate 12 erected on each steel support 4 is half the width of the steel support 4.

[0032] The scheme is further optimized. The inner edge formwork support system of the steel support includes an inner edge steel plate 2 and an end sealing strip 24. The inner edge steel plate 2 is fixedly installed on the inner edge support reinforcement 10 of the steel support connecting pad 5 and / or the steel support 4. The end sealing strip 24 is set at both ends of the inner edge steel plate 2 along the excavation direction.

[0033] The scheme is further optimized. The inner edge steel plate 2 includes a second cuboid steel plate 22, a second stepped steel plate 23, and a second hole-covering body 27. The second cuboid steel plate 22 is provided with bolt reserved holes 26 and second anchor rod reserved holes 25. The second hole-covering body 27 is adapted to the second anchor rod reserved holes 25. The second cuboid steel plate 22 is fixedly connected to the inner edge frame reinforcement 10 by bolts 21. Adjacent two second cuboid steel plates 22 are overlapped by the second stepped steel plate 23.

[0034] The hollow grouting anchor rod 7 is further optimized by including a rod body 72. One end of the rod body 72 is provided with a tail grouting hole 74, and the other end of the rod body 72 is equipped with an anchor plate 71 and a sealing valve. The end of the rod body 72 near the anchor plate 71 is provided with a rod body grouting hole 73. The rod body 72 is connected to the concrete spraying pipe 11 of the grouting equipment through the sealing valve.

[0035] The scheme was further optimized by installing pressure sensors 8 inside the over-excavated cavity 3. The pressure sensors 8 were installed at the deepest and highest points of the over-excavated cavity 3, respectively. The pressure data of the pressure sensors 8 were led out to the initial support through the sensor data line 81.

[0036] Example 2 like Figures 1 to 17 As shown, the present invention provides a high-efficiency construction device for rapid backfilling and shotcrete application in tunnel over-excavation, which includes a non-reusable steel support outer edge formwork support system for rapid backfilling of over-excavation, and a reusable steel support inner edge formwork support system.

[0037] After tunnel blasting and excavation, over-excavated grooves or cavities 3 are created. After the steel supports 4 are in place, the steel support connecting pads 5 are aligned, and the connecting bolts 21 are tightened. After the steel supports 4 are firmly fixed, an outer edge steel plate 1 is set around the over-excavated cavity 3. One end of the outer edge steel plate 1 can be firmly connected to the welding point of the outer edge support reinforcement 6, or it can be welded to the steel support connecting pad 5. This ensures that the steel supports 4 have sufficient protective layer thickness in the initial support. At this time, the outer edge steel plate 1 is located outside the steel mesh of the initial support and is used as a temporary template for shotcrete operation at the over-excavated cavity 3. The outer edge steel plate 1 includes a first cuboid steel plate 12, a first stepped steel plate 13, and a first hole-covering body 14. The first cuboid steel plate 12 is provided with a first anchor bolt reserved hole 101, and the first hole-covering body 14 is adapted to the first anchor bolt reserved hole 101.

[0038] The outer steel plate 1 can be made of U-shaped bent color steel plate or thin steel plate, and the plates are overlapped in an interlocking manner. Asbestos tiles are not allowed. Both sides of the steel plate should be roughened to increase the bonding force with the concrete. The outer steel plate 1 has a reserved hole 101 for the first anchor rod, which is convenient for the hollow grouting anchor rod 7 to pass through the outer steel plate 1 during construction. The hollow grouting anchor rod 7 is installed at the over-excavated cavity 3 to facilitate grouting and effectively enhance the reinforcement and suspension of the rock mass at the over-excavated cavity 3. As shown in the figure, the hollow grouting anchor rod 7 includes a rod body 72. One end of the rod body 72 is provided with a tail grouting hole 74. The other end of the rod body 72 is equipped with an anchor plate 71 and a sealing valve. The end of the rod body 72 near the anchor plate 71 is provided with a rod body grouting hole 73. The rod body 72 is connected to the grouting equipment through the sealing valve.

[0039] A pressure sensor 8 is installed at the deepest and highest points of the over-excavated cavity 3, and the pressure data of the grouting pressure sensor 8 is led out to the initial support through the sensor data line 81. This is to test the pressure after grouting is completed and to control whether the backfill grouting is dense.

[0040] After addressing the over-excavated grooves or cavities 3 or related work, shotcrete construction is carried out. After the steel support 4 is in place, an inner edge steel plate 2 is installed in the shotcrete construction section. One end of the inner edge steel plate 2 can be connected to the inner edge support reinforcement 10 by bolts 21, or it can be connected to the steel support connecting pad 5. The inner edge formwork support system of the steel support includes the inner edge steel plate 2 and the end sealing strip 24. The inner edge steel plate 2 includes a second cuboid steel plate 22, a second stepped steel plate 23, and a second hole-covering body 27. The first cuboid steel plate 12 is provided with bolt reserved holes 26 and second anchor bolt reserved holes 25. The second hole-covering body 27 is adapted to the second anchor bolt reserved holes 25.

[0041] The inner edge steel plate 2 can be made of U-shaped bent color steel plate or thin steel plate. It is composed of a second rectangular steel plate 22 and a second stepped steel plate 23, which are overlapped to form the inner edge steel plate of the initial support shotcrete. The second rectangular steel plate 22 is used at one end of the tunnel inner surface 9 after the initial support has been completed in the previous excavation, and the second stepped steel plate 23 is used at the end near the working face in the excavation direction. The two adjacent inner edge steel plates 2 are firmly overlapped together with bolt pre-drilled holes 26. When construction is required, thin concrete is shotcreted on the surface. End sealing strips 24 are set at both ends of the inner edge steel plate along the excavation direction to ensure the sealing of the connection between the second rectangular steel plate 22 and the anchor bolt, as well as the connection between the second rectangular steel plate 22 and the second stepped steel plate 23, so as to prevent the grout from overflowing during grouting. At this time, the inner edge steel plate 2 can be removed, ground, and put into the next unit of shotcrete construction. The inner edge steel plate 2 has a reserved hole 25 for the second anchor rod, which is convenient for the hollow grouting anchor rod 7 to pass through the inner edge steel plate 2 during construction.

[0042] Example 3 A method for rapid backfilling and shotcreting of tunnel over-excavation using the efficient construction device for rapid backfilling and shotcreting of tunnel over-excavation as described in Example 1 or Example 2, comprising the following steps: S1. Rapid backfilling of tunnel over-excavation; S11, Preset pressure sensor 8: Preset a pressure sensor 8 at the deepest point and the top of the over-excavated cavity 3, and lead the sensor data line 81 out of the initial support to facilitate subsequent testing of the grouting pressure inside the over-excavated cavity 3, and determine whether the over-excavated cavity 3 is filled with grout and whether the backfill is compacted by the pressure. S12. Ensure the thickness of the protective layer of steel support 4: After steel support 4 is in place, set the outer edge support 6; S13. Install anchor bolt holes in the surrounding rock of the tunnel; S14. Install the outer edge template; S15. Drive the hollow grouting anchor 7 into the anchor drill hole, and make the hollow grouting anchor 7 pass through the reserved hole reserved in the outer edge template, and close the sealing valve 75. S16. Shotcrete construction: Start shotcrete operation on the outer edge steel plate 1 until the steel support 4 is covered and the protective layer and initial support thickness meet the requirements. At this time, the over-excavated cavity 3 behind the initial support is still in the state of unfilled cavity. S17. Grouting operation: After the initial support shotcrete operation is completed and reaches 70% strength, the initial support is closed and can be used as a template for backfilling grouting. Grouting is injected into the over-excavated cavity 3 through the hollow grouting anchor 7 until the pressure sensor 8 shows that the grouting cavity has been backfilled and compacted. At this time, grouting is stopped and the sealing valve 75 is closed. S18. When the strength of the grout reaches 70% of the design strength, cut off the part of the hollow grouting anchor 7 that extends out of the initial support surface to ensure that the initial support surface is flat and aesthetically pleasing. S2, rapid tunnel construction; S21. Install the inner edge template; S22. Set anchor bolt holes in the surrounding rock of the tunnel, avoiding the anchor bolt hole locations in step S13; S23. Drive the hollow grouting anchor rod 7 into the anchor rod drill hole of step S22, and make the hollow grouting anchor rod 7 pass through the reserved hole reserved in the inner edge template, and close the sealing valve 75. S24. Spray a thin layer of concrete onto the inner edge formwork surface until it covers the entire inner edge formwork. S25. Grouting is performed on the construction section where the shotcrete was applied in step S24 through the grouting hole 73 of the hollow grouting anchor rod 7. S26. After the grout has solidified, remove the inner edge template, grind it, and repeat steps S22-S25 above for continuous construction.

[0043] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency construction device for rapid backfilling and shotcrete application in tunnel over-excavation, characterized in that, include: Steel support (4), and a steel support connecting plate (5) is provided between two adjacent steel supports (4); The steel support outer edge formwork support system is fixedly set on the outside of the steel support (4) and located on the outside of the steel mesh in the initial support. The steel support outer edge formwork support system is used to seal the over-excavated voids (3) in the tunnel. The inner edge formwork support system of the steel support is fixedly set on the inner side of the steel support (4) and located on the inner side of the steel mesh in the initial support. The area between the outer edge formwork support system of the steel support and the inner edge formwork support system of the steel support is the tunnel over-excavation rapid backfill area. Hollow grouting anchor (7) is installed at the over-excavated cavity (3) and is used to grout the over-excavated cavity (3) and the rapid backfilling area of ​​the over-excavated tunnel.

2. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 1, characterized in that, The outer edge formwork support system of the steel support includes an outer edge steel plate (1), which is fixedly installed on the steel support connecting pad (5) and / or the outer edge support reinforcement (6) of the steel support (4); the two sides of the outer edge steel plate (1) are roughened.

3. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 2, characterized in that, The outer steel plate (1) includes a first cuboid steel plate (12), a first stepped steel plate (13), and a first hole-covering body (14); the first cuboid steel plate (12) is provided with a first anchor rod reserved hole (101), and the first hole-covering body (14) is adapted to the first anchor rod reserved hole (101); two adjacent first cuboid steel plates (12) are overlapped by the first stepped steel plate (13); the two sides of the first cuboid steel plate (12) are roughened.

4. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 2, characterized in that, The length of the outer edge support bar (6) is 4cm-5cm.

5. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 3, characterized in that, The two ends of the first cuboid steel plate (12) are respectively erected on the two adjacent steel supports (4), and the length of the first cuboid steel plate (12) erected on each steel support (4) is half the width of the steel support (4).

6. The efficient construction device for rapid backfilling and shotcrete application in tunnels according to claim 1, characterized in that, The inner edge formwork support system of the steel support includes an inner edge steel plate (2) and an end sealing strip (24). The inner edge steel plate (2) is fixedly installed on the steel support connecting pad (5) and / or the inner edge support bar (10) of the steel support (4). The end sealing strip (24) is set at both ends of the inner edge steel plate (2) along the excavation direction.

7. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 6, characterized in that, The inner edge steel plate (2) includes a second cuboid steel plate (22), a second stepped steel plate (23), and a second hole-covering body (27); the second cuboid steel plate (22) is provided with bolt reserved holes (26) and second anchor rod reserved holes (25), and the second hole-covering body (27) is adapted to the second anchor rod reserved holes (25); the second cuboid steel plate (22) is fixedly connected to the inner edge support bar (10) by bolts (21); two adjacent second cuboid steel plates (22) are overlapped by the second stepped steel plate (23).

8. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 1, characterized in that, The hollow grouting anchor rod (7) includes a rod body (72), one end of which is provided with a tail end grouting hole (74), and the other end of which is installed with an anchor plate (71) and a sealing valve. The end of the rod body (72) near the anchor plate (71) is provided with a rod body grouting hole (73), and the rod body (72) is connected to the concrete spraying pipe (11) of the grouting equipment through the sealing valve.

9. The efficient construction device for rapid backfilling and shotcrete application in tunnel over-excavation according to claim 1, characterized in that, Pressure sensors (8) are installed inside the over-excavated cavity (3). The pressure sensors (8) are respectively installed at the deepest and highest points of the over-excavated cavity (3). The pressure data of the pressure sensors (8) is led out to the initial support through the sensor data line (81).

10. A method for efficient construction of tunnel over-excavation, rapid backfilling, and shotcrete, characterized in that, The efficient construction device for rapid backfilling and shotcreting of tunnel over-excavation as described in any one of claims 1-9 includes the following steps: S1. Rapid backfilling of tunnel over-excavation; S11. Pre-set pressure sensors (8) at the deepest point and the top of the over-excavated cavity (3), and lead out the sensor data line (81) to the initial support. S12. Set steel support (4). After the steel support (4) is in place, set outer edge support reinforcement (6). S13. Install anchor bolt holes in the surrounding rock of the tunnel; S14. Install the outer edge template; S15. Drive the hollow grouting anchor (7) into the anchor hole and pass the hollow grouting anchor (7) through the reserved hole reserved in the outer edge template, and close the sealing valve (75). S16. Shotcrete construction: Shotcrete is applied to the outer edge steel plate (1) until it covers the steel support (4) to the protective layer and the initial support thickness meets the requirements. S17. Grouting operation: After the initial support shotcrete operation is completed and reaches 70% strength, grout is injected into the over-excavated cavity (3) through hollow grouting anchor (7) until the pressure sensor (8) shows that the grouting cavity has been backfilled and compacted. Then, grouting is stopped and the sealing valve (75) is closed. S18. When the strength of the grout reaches 70% of the design strength, cut off the part of the hollow grouting anchor (7) that extends out of the initial support surface to ensure that the initial support surface is flat and beautiful. S2, rapid tunnel construction; S21. Install the inner edge template; S22. Set anchor bolt holes in the surrounding rock of the tunnel, avoiding the anchor bolt hole locations in step S13; S23. Drive the hollow grouting anchor rod (7) into the anchor rod drill hole of step S22, and make the hollow grouting anchor rod (7) pass through the reserved hole reserved in the inner edge template, and close the sealing valve (75). S24. Spray a thin layer of concrete onto the inner edge formwork surface until it covers the entire inner edge formwork. S25. Grout the construction section of the shotcrete in step S24 through the grouting hole (73) of the hollow grouting anchor (7); S26. After the grout has solidified, remove the inner edge template, grind it, and repeat steps S22-S25 above for continuous construction.

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