Tunnel primary support formwork for building concrete air bag and construction method thereof

Abstract

This invention provides a concrete airbag template for tunnel initial support and its construction method, including a support frame and an airbag support assembly. The airbag support assembly includes an airbag template connected to the support frame. The support frame includes a fixed arch frame with multiple fixing hooks on its sides. The airbag template includes a second airbag, which is an inner soft bag, and a third airbag, which is an outer hard bag, is fitted around it. The outer surfaces of the second and third airbags are respectively provided with a first pouring hole and a second pouring hole, which are interconnected. This invention, through an airbag template composed of a second and a third airbag, is easier to move and transport after deflating compared to traditional templates. Furthermore, it only requires inflation during use, replacing traditional shotcrete with a method of pouring fast-setting concrete, thus fundamentally solving the problem of high rebound during concrete shotcreting.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a concrete airbag formwork for initial tunnel support and its construction method. Background Technology

[0002] Currently, in tunnel construction both domestically and internationally, the traditional method for initial shotcrete support construction is as follows: First, shotcrete material is injected into a shotcrete machine (hereinafter referred to as the shotcrete machine). Then, through a shotcrete pipe and high-pressure air, the shotcrete operator controls the nozzle and sprays the material onto the surrounding rock surface. Shotcreting requires layering, with each layer having a specific thickness. For example, the initial support thickness is At this time, cyclic spraying is required. Secondly, the initial support construction process generally adopts wet-sprayed concrete, which has the following shortcomings: The first type of wet-sprayed concrete exhibits a relatively high rebound rate, with the average rebound rate generally averaging around [missing information]. As per construction specifications, rebounded concrete cannot be collected and reused. Therefore, a high rebound rate leads to a waste of raw materials and generates significant dust on construction sites. Prolonged inhalation of this dust can easily cause lung-related diseases among workers. Currently, construction companies are investing considerable manpower and resources in technical improvements and strengthened management to control the rebound rate, but they are still only able to keep it within a certain range. Between these points, the normal amount of shotcrete used per meter of the upper arch tunnel is: The concrete loss per kilometer of tunnel due to rebound reaches [amount missing]. ; Secondly, when constructing tunnels under adverse geological conditions such as high geothermal activity, abundant water, high altitude, and low temperatures, the rebound rate of shotcrete is higher due to the influence of low temperature, low air pressure, and other regional environments. In contrast, the amount of concrete spraying work that can be completed in 3 hours in plains areas would take much longer in harsh environments. It takes hours to complete, which exacerbates the excessive consumption of shotcrete, increases construction costs, and causes serious economic losses and environmental pollution; Preliminary support is usually not done by pouring concrete. Although pouring concrete can avoid high rebound rate and effectively reduce losses compared to shotcreting, traditional concrete sets slowly and the waiting time for initial setting is long. Therefore, shotcreting is mostly used in the preliminary support of tunnel concrete, and pouring is not considered. Therefore, a concrete airbag formwork for tunnel initial support and its construction method are proposed to solve the problems mentioned above. Summary of the Invention

[0003] The main objective of this invention is to provide a concrete airbag formwork for tunnel initial support and its construction method, thereby solving the problem of high rebound rate of existing concrete during spraying operations.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a concrete airbag formwork for tunnel initial support construction, including a support frame and an airbag support assembly; The airbag support assembly includes an airbag template, which is connected to a support frame.

[0005] In the preferred embodiment, the support frame includes a fixed arched frame, and multiple fixing hooks are provided on the side of the fixed arched frame. The airbag template includes a second airbag, which is an inner soft bag, and a third airbag is provided on the outside, which is an outer hard bag. The outer surfaces of the second airbag and the third airbag are respectively provided with a first pouring hole and a second pouring hole, which are interconnected. A small vibrator is provided on the inner wall of the second airbag, and the third airbag is connected to the fixing hooks by a binding rope.

[0006] In a preferred embodiment, the support frame includes two movable support frames. A connecting frame is provided on the top of the movable support frame. A vertical plate is provided between the connecting frame and the movable support frame. A connecting arched frame connected to the connecting frame is fitted on the outside of the movable support frame. A worktable is provided between the two connecting arched frames. The movable support frame is an N-shaped frame, which includes two vertical bars and one horizontal bar. A side plate is provided on the side of one vertical bar facing the other vertical bar. A mounting horizontal plate is provided between the two horizontal bars and is located between the two vertical plates.

[0007] In a preferred embodiment, the airbag support assembly further includes a telescopic rotating arm mechanism, an airbag retraction mechanism, and a support assembly. The telescopic rotating arm mechanism includes a coaxial dual-axis motor, which is located on the top of the mounting horizontal plate and between the two vertical plates. Both output shafts of the coaxial dual-axis motor are provided with a drive shaft that penetrates the vertical plate and extends to the outside of the vertical plate. The drive shafts are connected to the vertical plates through bearings. Each of the two drive shafts has a first telescopic rod at one of its opposite ends. The two first telescopic rods are respectively located on opposite sides of the two vertical plates. The output ends of the two first telescopic rods are connected to each other through a connecting horizontal plate. The upper surface of the connecting horizontal plate is provided with mounting holes.

[0008] In a preferred embodiment, the airbag winding mechanism includes a winding roller and a guide roller, both of which are disposed between two side plates, with the guide roller located below the winding roller. A winding motor is disposed on the side of one side plate away from the winding roller, and the output shaft of the winding motor is connected to the winding roller.

[0009] In a preferred embodiment, the airbag template includes a first airbag, one end of which is wound around the outside of the take-up roller, and the other end extends above the connecting cross plate and is connected to the connecting cross plate. A guide roller is disposed on the path of the extension of the first airbag and is in close contact with the first airbag. The guide roller is used to guide and support the first airbag.

[0010] In a preferred embodiment, a spray hole is provided on the side of the first airbag away from the support frame. The spray hole is located above the mounting hole and is interconnected with the mounting hole. The concrete nozzle is located on the lower surface of the connecting horizontal plate and extends through the mounting hole into the interior of the spray hole. The concrete nozzle is interconnected with the shotcrete machine through a delivery pipe. Side holes are provided on both sides of the first airbag. The two side holes are interconnected with the air inlet pipe and the air extraction pipe, respectively. The other end of the air inlet pipe is connected to the air pump, and the other end of the air extraction pipe is connected to the air extraction pump.

[0011] In a preferred embodiment, the support assembly includes two sets of second telescopic rods. Each of the two connecting arched frames has a set of second telescopic rods on opposite sides. Each set of second telescopic rods includes at least N second telescopic rods, where N is a positive integer. The N second telescopic rods are symmetrically distributed with the upright plate as the center line. An arc-shaped movable bracket is provided at the output end of the second telescopic rod. The arc-shaped movable bracket includes an arc-shaped plate provided at the output end of the second telescopic rod. An opening groove is provided on the side of the arc-shaped plate away from the second telescopic rod. A rotating roller is provided between the two side walls of the opening groove. The rotating roller is in contact with the surface of the first airbag facing the support frame.

[0012] In the preferred embodiment, the coaxial dual-axis motor, the first telescopic rod, the winding motor, the air pump, the air pump, and the second telescopic rod are linked and controlled together.

[0013] A method for constructing a concrete airbag formwork for the initial support of a tunnel involves performing shotcrete construction on the excavated tunnel segments along the longitudinal extension of the tunnel, from back to front. The construction method for the initial support shotcrete is consistent across multiple tunnel segments. When performing shotcrete construction on any tunnel segment, the following steps are included: S1. After the support frame is installed in the area inside the tunnel where the concrete will be sprayed, the second and third airbags are moved into the inside of the support frame and connected to each other by binding ropes and fixing hooks to fix the third airbag to the support frame. The airbags are then inflated by an air pump so that both the second and third airbags are fully inflated. After the second and third airbags are fully inflated, the tunnel end plate is used to seal both sides of them. Then, quick-setting concrete is poured between the third airbag and the rock base through the first and second pouring holes. The concrete is then vibrated using a small vibrator. After the vibration is completed and the concrete has set, the second and third airbags are deflated and the formwork is removed. S3. Repeat the above process until all tunnel segments in the tunnel under construction have been poured with concrete.

[0014] This invention provides a concrete airbag formwork for initial tunnel support and its construction method. By adopting the above solution, the following beneficial effects are achieved: 1. The present invention uses an airbag template composed of a second airbag and a third airbag. Compared with traditional templates, the airbag template is easy to transport and move after being deflated, and only needs to be inflated during use. In the tunnel construction process, it replaces the traditional shotcrete by pouring quick-hardening concrete, thereby solving the problem of high rebound rate in the shotcrete process from the root. 2. The system includes a support frame, airbag support components, and other components. By moving the support components and cooperating with the airbag support components, during the initial support of the tunnel, the first airbag is inflated to full capacity. The airbag template then restricts the concrete spraying area between the first airbag and the tunnel foundation, preventing concrete from splashing and rebounding due to the impact of the spraying. 3. Through the setting of airbag support components and support components, under the action of the first telescopic rod and the second telescopic rod, the airbag mold can be used to restrain concrete spraying operations during tunnel construction, whether it is leveling or secondary lining. Furthermore, the airbag mold can be adjusted according to actual construction needs during the restraint process. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a structural schematic diagram of a concrete airbag formwork for the initial support of a tunnel, provided by an embodiment of the present invention. Figure 2 for Figure 1 Another structural diagram from another perspective; Figure 3 for Figure 2 Structural sectional view; Figure 4 for Figure 3 Another structural diagram from another perspective; Figure 5 This is a schematic diagram of the support frame in an embodiment of the present invention; Figure 6 for Figure 5 Another structural diagram from another perspective; Figure 7 This is a schematic diagram of the telescopic rotating arm mechanism in an embodiment of the present invention; Figure 8This is a schematic diagram of the structure of the airbag template in an embodiment of the present invention; Figure 9 This is a schematic diagram of the arc-shaped movable support structure in an embodiment of the present invention; Figure 10 This is a schematic diagram showing the usage state of the airbag template in an embodiment of the present invention; Figure 11 for Figure 10 Another structural diagram from another perspective; Figure 12 This is a schematic diagram of an embodiment of the present invention; Figure 13 for Figure 12 A magnified structural diagram of point A in the middle.

[0016] The attached diagram lists the components represented by each number as follows: 1. Support frame; 101. Movable support frame; 102. Connecting frame; 103. Mounting horizontal plate; 104. Connecting arch frame; 105. Worktable; 106. Vertical plate; 107. Side plate; 108. Fixed arch frame; 109. Fixed hook; 2. Telescopic rotating arm mechanism; 21. Coaxial dual-axis motor; 22. Drive shaft; 23. First telescopic rod; 24. Connecting horizontal plate; 25. Mounting hole; 3. Winding motor; 4. Winding roller; 5. Guide roller 6. Airbag template; 61. First airbag; 62. Side hole; 63. Spray hole; 64. Second airbag; 65. Third airbag; 66. First pouring hole; 67. Second pouring hole; 68. Small vibrator; 7. Conveying pipe; 8. Air inlet pipe; 9. Concrete nozzle; 10. Second telescopic rod; 11. Arc-shaped movable support; 111. Arc plate; 112. Opening slot; 113. Rotating roller; 12. Air extraction pipe; 13. Binding rope; 14. Tunnel. Detailed Implementation

[0017] Example 1: like Figure 12 and 13 As shown, a type of concrete airbag formwork for tunnel initial support includes a support frame 1 and an airbag support assembly. The airbag support assembly includes an airbag template 6, which is connected to the support frame 1; The support frame 1 includes a fixed arch frame 108, and the side of the fixed arch frame 108 is provided with multiple fixed hooks 109. The airbag template 6 includes a second airbag 64, which is an inner soft bag and is covered with a third airbag 65, which is an outer hard bag. The outer surfaces of the second airbag 64 and the third airbag 65 are respectively provided with a first pouring hole 66 and a second pouring hole 67, which are interconnected. The inner wall of the second airbag 64 is provided with a small vibrator 68. The third airbag 65 is connected to the fixed hooks 109 by a binding rope 13. Based on the above, in this embodiment, by setting an integrated second airbag 64 and a third airbag 65, the two work together to form a movable template. Compared with traditional templates, this template is easy to move and use, and only needs to be inflated during use. It is convenient to use and highly flexible. Furthermore, by pouring concrete between the template and the rock base, the method of spraying concrete during the initial support is replaced, thereby completely solving the problem of rebound during the spraying concrete process. The concrete poured in the above process is preferably fast-hardening concrete.

[0018] A method for constructing a concrete airbag formwork for the initial support of a tunnel: Along the longitudinal extension direction of the tunnel 14 under construction, the tunnel is divided into multiple tunnel segments 14 from back to front, and initial support shotcrete construction is carried out on the excavated tunnel sections. The construction method for the initial support shotcrete of multiple tunnel segments 14 is consistent. When carrying out initial support shotcrete construction on any tunnel segment 14, the following steps are included: S1. After the support frame 1 is installed in the area to be sprayed concrete inside the tunnel 14, the second airbag 64 and the third airbag 65 are moved into the interior of the support frame 1 and connected to each other by the binding rope 13 and the fixing hook 109. The binding rope 13 is preferably made of steel wire to achieve the connection and fixation of the third airbag 65 to the support frame 1. The airbag 64 and the third airbag 65 are inflated by the air pump. After S2, the second airbag 64 and the third airbag 65 are all inflated, their sides are sealed by the tunnel sealing head, and concrete is poured between the third airbag 65 and the rock base through the first pouring hole 66 and the second pouring hole 67. The concrete is then vibrated by the small vibrator 68. After the vibration is completed and the concrete has set, the second airbag 64 and the third airbag 65 are deflated and the formwork is removed. S3. Repeat the above process until all tunnel segments in the tunnel 14 under construction have been poured with concrete.

[0019] Example 2: like Figure 1 , 2 As shown in Figures 3, 4, 10, and 11, a type of concrete airbag formwork for tunnel initial support includes a support frame 1 and an airbag support assembly. The airbag support assembly includes an airbag template 6, which is connected to the support frame 1; like Figure 5 and 6As shown, the support frame 1 includes two movable support frames 101. A connecting frame 102 is provided on the top of the movable support frame 101. A vertical plate 106 is provided between the connecting frame 102 and the movable support frame 101. A connecting arched frame 104 connected to the connecting frame 102 is sleeved on the outside of the movable support frame 101. A workbench 105 is provided between the two connecting arched frames 104. The movable support frame 101 is an N-shaped frame. The N-shaped frame includes two vertical bars and one horizontal bar. A side plate 107 is provided on the side of one vertical bar facing the other vertical bar. A mounting horizontal plate 103 is provided between the two horizontal bars. The mounting horizontal plate 103 is located between the two vertical plates 106. Based on the above, the mobile support frame 101, connecting frame 102, and connecting arch frame 104 cooperate to form the main body of the support frame, which plays the role of overall support. The mounting plate 103 and the worktable 105 not only connect the two sides of the main body of the support frame, but the mounting plate 103 also provides a carrier for the installation of the coaxial dual-axis motor 21. The worktable 105 makes it convenient for workers to stand on its surface to debug or maintain the equipment. The vertical plate 106 supports the drive shaft 22, and the side plate 107 supports the winding roller 4 and the guide roller 5.

[0020] like Figure 1 , 2 As shown in 3, 4 and 7, the airbag support assembly also includes a telescopic rotating arm mechanism 2, an airbag retraction mechanism and a support assembly. The telescopic rotating arm mechanism 2 includes a coaxial dual-axis motor 21. The coaxial dual-axis motor 21 is preferably a Siemens 6SL3120-2TE13-0AD0 dual-axis servo motor, and preferably uses a Siemens original matching SINAMICS series driver (actuator) in conjunction with the dual-axis servo motor. The coaxial dual-axis motor 21 is set on the top of the mounting plate 103 and is located between the two vertical plates 106. Both output shafts of the coaxial dual-axis motor 21 are provided with a drive shaft 22 that passes through the vertical plate 106 and extends to the outside of the vertical plate 106. The drive shaft 22 is connected to the vertical plate 106 through bearings. An angle sensor is provided at the connection between the drive shaft 22 and the vertical plate 106 to monitor the rotation angle of the first telescopic rod 23. Two drive shafts 22 are each equipped with a first telescopic rod 23 at opposite ends. The Tuoda TD-80 industrial-grade electric telescopic rod is preferred, and the Tuoanda TD-1248 wired controller (actuator) is preferred to be used in conjunction with the first telescopic rod 23. A wire displacement sensor is installed at the connection between the cylinder body and the piston rod of the first telescopic rod 23 to monitor the extension length of the first telescopic rod 23. The two first telescopic rods 23 are respectively installed on opposite sides of the two vertical plates 106. The output ends of the two first telescopic rods 23 are connected to each other through a connecting horizontal plate 24. The upper surface of the connecting horizontal plate 24 is provided with mounting holes 25. Based on the above, the coaxial dual-axis motor 21 drives the two first telescopic rods 23 to rotate simultaneously through the transmission shaft 22. The rotation direction and speed of the two first telescopic rods 23 are completely consistent. The connecting horizontal plate 24 is connected to the airbag template 6, and the mounting hole 25 allows the concrete nozzle 9 to be inserted into it.

[0021] like Figure 1 , 2 As shown in Figures 3 and 4, the airbag winding mechanism includes a winding roller 4 and a guide roller 5. Both the winding roller 4 and the guide roller 5 are located between two side plates 107, and the guide roller 5 is located below the winding roller 4. A winding motor 3 is provided on the side of one side plate 107 away from the winding roller 4. The winding motor 3 is preferably a Panasonic MSMD042G1U servo motor, and a Panasonic MADHT1505E driver (actuator) is preferably used in conjunction with the winding motor 3. The output shaft of the winding motor 3 is connected to the winding roller 4. An absolute encoder is provided at the output shaft of the winding motor 3 to calculate the length of the first airbag 61 after it is deployed by the number of rotations of the winding roller 4. like Figure 3 and 8 As shown, an airbag template 6 is wound around the outside of the take-up roller 4. The airbag template 6 includes a first airbag 61. A pressure sensor is installed inside the first airbag 61 to monitor the internal pressure after the first airbag 61 is inflated (usually needs to be maintained at 0.2-0.3MPa, which can be adjusted according to the actual construction needs). One end of the first airbag 61 is wound around the outside of the take-up roller 4, and the other end extends to the top of the connecting horizontal plate 24 and is connected to the connecting horizontal plate 24. The guide roller 5 is set on the path of the extension of the first airbag 61 and is in close contact with the first airbag 61. The guide roller 5 is used to guide and support the first airbag 61. The first airbag 61 has a spray hole 63 on the side opposite to the support frame 1. The spray hole 63 is located above the mounting hole 25 and is connected to the mounting hole 25. The concrete nozzle 9 is located on the lower surface of the connecting horizontal plate 24 and extends through the mounting hole 25 into the interior of the spray hole 63. The first airbag 61 has side holes 62 on both sides. The two side holes 62 are connected to the air inlet pipe 8 and the air extraction pipe 12 respectively. The other end of the air inlet pipe 8 is connected to the air pump, and the other end of the air extraction pipe 12 is connected to the air extraction pump. Based on the above, when the winding motor 3 is powered on, it drives the winding roller 4 to rotate, thereby realizing the winding or unwinding operation of the first airbag 61. If the winding roller 4 can wind the first airbag 61 when it rotates counterclockwise, then it is in the unwinding state when it rotates clockwise, and vice versa. The guide roller 5 plays the role of guiding the unwinding and winding direction of the first airbag 61. like Figure 8As shown, the airbag template 6 has a spray hole 63 on the side away from the telescopic rotating arm mechanism 2. A concrete nozzle 9 is installed inside the spray hole 63. The concrete nozzle 9 is connected to the shotcrete machine through the delivery pipe 7. A concrete pressure sensor is installed near the concrete nozzle 9 on the delivery pipe 7 to monitor the pressure of the sprayed concrete. The airbag template 6 is connected to the air pump through the air inlet pipe 8. The air pump is preferably a Kaishan KSDY-12 / 10 electric mobile screw air compressor, and the Invt CHF1000 series frequency converter (actuator) is preferably used in conjunction with the air pump. It is also connected to the air pump through the air extraction pipe 12. The air pump is preferably a German Busch R5-300 rotary vane vacuum pump, and the ULVAC-R20 series vacuum controller (actuator) is preferably used in conjunction with the air pump. Based on the above, the side hole 62 allows the first airbag 61 to be inflated by the air pump and the air inlet pipe 8, changing the first airbag 61 from a deflated state to a fully inflated state. The fully inflated first airbag 61 restricts the shotcrete, confining the concrete between the first airbag 61 and the tunnel foundation, preventing high rebound of the concrete during spraying. The air extraction pipe 12 on the other side works in conjunction with the air extraction pump to extract the gas inside the first airbag 61 in the fully inflated state, restoring the first airbag 61 to a deflated state. The spray hole 63 corresponding to the mounting hole 25 ensures that the concrete nozzle 9 can spray concrete from the spray hole 63, and the sprayed concrete fills the space between the tunnel foundation and the first airbag 61.

[0022] like Figure 1 , 2 As shown in Figures 3 and 4, the support assembly includes two sets of second telescopic rods 10. The GWD-100 industrial telescopic rod of the Gewa electric cylinder is preferred, and the Xinje DS50 series servo drive (actuator) is preferred to be used in conjunction with the second telescopic rods 10. The connection between the cylinder body and the piston rod of the second telescopic rod 10 is used to monitor the extension length of the second telescopic rod 10. A set of second telescopic rods 10 is provided on each side of the two connecting arched frames 104. A set of second telescopic rods 10 includes at least 2N second telescopic rods 10, where N is a positive integer. The 2N second telescopic rods 10 are symmetrically distributed with the vertical plate 106 as the center line. The output end of the second telescopic rod 10 is provided with an arc-shaped movable bracket 11. like Figure 9 As shown, the arc-shaped movable support 11 includes an arc-shaped plate 111 disposed at the output end of the second telescopic rod 10. An opening groove 112 is provided on the side of the arc-shaped plate 111 away from the second telescopic rod 10. A rotating roller 113 is disposed between the two side walls of the opening groove 112. The rotating roller 113 is in contact with the surface of the first airbag 61 facing the support frame 1. Based on the above, the support component plays the role of supporting the first airbag 61. By driving the second telescopic rod 10, the arc-shaped movable bracket 11 can move along the direction of the second telescopic rod 10. When the arc-shaped movable bracket 11 comes into contact with the first airbag 61, it can support the first airbag 61 and ensure that the shape of the first airbag 61 is fixed. When the arc-shaped movable bracket 11 returns to the extended state, it facilitates the unwinding operation of the first airbag 61.

[0023] The coaxial dual-axis motor 21, the first telescopic rod 23, the winding motor 3, the air pump, the air pump, and the second telescopic rod 10 are linked and controlled. The linkage control is achieved by the main controller and multiple actuators working together. The specific usage is shown below: The main controller is preferably a Siemens S7-1200 series PLC controller. This PLC controller is set on the upper surface of the mounting plate 103 to receive sensor signals and output control commands according to the preset program. This controller is the core device of the linkage control.

[0024] A method for constructing a concrete airbag formwork for the initial support of a tunnel involves performing shotcrete construction on multiple tunnel segments (14 sections) from back to front along the longitudinal extension direction of the tunnel being constructed. The construction method for the initial support shotcrete construction on multiple tunnel segments (14 sections) is consistent. When performing initial support shotcrete construction on any one tunnel segment (14 sections), the following steps are included: S1. The support frame 1 moves to the area inside the tunnel 14 where the concrete is to be sprayed. At this time, the airbag template 6 is in a retracted state, the first telescopic rod 23 is not extended, and it is in a horizontal state. At this time, the first airbag 61 is in an uninflated state; S2. The initial support shotcrete construction process for the tunnel is as follows: Before the initial shotcrete leveling of S21 and Tunnel 14, pretreatment is carried out, namely, removing gangue and loose rocks, and then removing dust, mud, wood chips and oil stains and other impurities from the base surface to provide installation conditions for the subsequent support structure. S22. After pretreatment, the base surface is pretreated by spraying concrete. The pretreatment process is as follows: S221. By driving the first telescopic rod 23, the output end of the first telescopic rod 23 extends, and after extension, the distance between the first airbag 61 and the base surface is... The thickness of the first airbag 61 after inflation is , ; S222. After the first telescopic rod 23 extends to the preset position, it drives the coaxial dual-axis motor 21, the winding motor 3, the air pump, and the shotcrete machine. The coaxial dual-axis motor 21 drives the first telescopic rod 23 to rotate around the transmission shaft 22 through the transmission shaft 22. The winding motor 3 drives the winding roller 4 to rotate and unwind the first airbag 61 which is in the winding state. The shotcrete machine transports the concrete through the conveying pipe 7 to the concrete nozzle 9 for spraying. Based on the above, while the first airbag 61 is unwinding, the first telescopic rod 23 drives the first airbag 61 to unfold along a fixed path. During the unfolding process, the air pump rapidly inflates the first airbag 61, so that the unfolded part of the first airbag 61 is inflated to a full state. After being inflated, the shotcrete machine works to spray concrete through the concrete nozzle 9. The sprayed concrete adheres to the rock base surface. That is, during the unwinding process, timely inflation and simultaneous shotcrete operation are carried out, so that the first airbag 61 is gradually unfolded while the concrete spraying operation is carried out. The above process is repeated until the construction of the area is completed and a concrete base surface is formed. During the construction process, the second telescopic rod 10 works to drive the arc-shaped movable support 11 to move towards the first airbag 61, so that the arc-shaped movable support 11 contacts the first airbag 61 to support the first airbag 61. After the construction is completed, the air pump stops working, and at this time the unfolded first airbag 61 is in a fully inflated state. S3. After the initial concrete spraying is completed, wait for the concrete to initially set. Minutes, after initial setting, during final setting Hours ago, the support frame 1 was removed from the area, and the first telescopic rod 23, the take-up roller 4 and the second telescopic rod 10 were reset while the air pump was started, so that the first airbag 61, which had been expanded, changed from an inflated state to a deflated state and was rewound around the outside of the take-up roller 4 to complete the storage operation. The arch frame and steel mesh were then installed. After the installation was completed, the support frame 1 was moved back to the construction area. After the arch frame and steel mesh are installed (S4), repeat the construction process of S221, so that the output end of the first telescopic rod 23 extends. At this time, the distance between the first airbag 61 and the concrete base surface after extension is [missing information]. The thickness of the first airbag 61 after inflation is , After the first telescopic rod 23 extends to the preset position, the first airbag 61 deployment step in the S222 construction process is repeated so that the first airbag 61 is fully deployed and kept in a full state. At this time, tunnel end plates are installed on both sides of the deployed first airbag 61, and concrete is poured between the first airbag 61 and the concrete base through the concrete nozzle 9 to complete the concrete pouring operation in the secondary lining process. S5. Initial shotcrete construction of the next tunnel segment: Following the methods in S1-S4, initial shotcrete construction of the tunnel segment is carried out until the shotcrete construction of the tunnel support of all tunnel segments in the tunnel 14 under construction is completed.

[0025] The linkage process during the above construction is as follows: 1. Inflation stage (corresponding to construction step S222): Objective: The first airbag 61 unfolds from its retracted state to an arc that matches the tunnel base surface, and inflates to full capacity, while the second telescopic rod 10 provides support simultaneously.

[0026] Linkage logic: After the proximity sensor detects that the support frame 1 is in place, it sends a "position signal" to the PLC controller (hereinafter referred to as PLC), and the PLC starts the process; The PLC commands the first telescopic rod 23 to extend, and the wire displacement sensor provides real-time feedback on the extension length. When the preset L1 (distance between the airbag and the base surface) is reached, the first telescopic rod stops extending. The PLC synchronously instructs the take-up motor 3 to rotate in the forward direction (unwind), and the absolute encoder provides real-time feedback on the airbag deployment length. At the same time, it instructs the coaxial dual-axis motor 21 to drive the transmission shaft 22 to rotate, and the angle sensor provides feedback on the rotation angle to ensure that the airbag deployment path is consistent with the curvature of the tunnel arch (e.g., 90° rotation angle at the arch top and 30° at the sidewall). After unwinding begins, the PLC commands the air pump to start, and the pressure sensor monitors the airbag pressure in real time: when the pressure is below 0.2MPa, the pump controller increases the inflation flow rate; when it reaches 0.25MPa, the flow rate is kept stable. When the airbag unfolds to the construction length of the segment (the encoder feedback value meets the standard), the PLC commands the winding motor 3 to stop unwinding and the coaxial dual-axis motor 21 to stop rotating; at the same time, it commands the second telescopic rod (10) to extend, and its displacement sensor provides feedback on the extension length until the rotating roller 113 of the arc-shaped movable bracket 11 comes into contact with the first airbag 61 (the displacement sensor provides feedback "in place" when in contact), and then stops extending.

[0027] 2. Concrete spraying stage (corresponding to construction steps S222 and S4): Objective: Concrete nozzle 9 delivers precise spray, and the first airbag 61 remains fully inflated for stable support.

[0028] Linkage logic: After the airbag pressure stabilizes, the PLC commands the shotcrete machine to start, and the concrete pressure sensor monitors the spraying pressure: if the pressure is >0.5MPa, the PLC commands the shotcrete machine to reduce the output; if it is <0.3MPa, the output is increased. During the spraying process, the pressure sensor continuously monitors the airbag pressure: if the pressure drops (<0.2MPa) due to the impact of concrete, the PLC instructs the air pump to replenish the pressure; The displacement sensor of the second telescopic rod 10 provides real-time feedback on the support status: if the airbag expands outward due to the injection pressure, causing the support spacing to increase, the PLC instructs the second telescopic rod 10 to extend synchronously to maintain the support force.

[0029] 3. Rewinding and resetting stage (corresponding to construction step S3): Objective: Deflate and retract the first airbag 61, and reset all components to their initial state.

[0030] Linkage logic: After the concrete has initially set (the "rewinding command" is manually triggered via HMI), the PLC commands the shotcrete machine to stop working. Command the second telescopic rod 10 to retract (stop after the displacement sensor reports that it has fully retracted); The command pump starts, and the pressure sensor monitors the airbag pressure: when the pressure drops below 0.05MPa (the airbag deflates), the pump stops. The PLC commands the winding motor 3 to rotate in the reverse direction (winding), and simultaneously commands the first telescopic rod 23 to retract (the displacement sensor reports that it is fully retracted) and the coaxial dual-axis motor 21 to reverse (the angle sensor reports that it has been reset to the horizontal state). The absolute encoder detects that the airbag winding is complete (return count is zero), the PLC commands the winding motor 3 to stop, and all components are reset.

[0031] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A concrete airbag formwork for initial tunnel support, characterized in that: Includes support frame (1) and airbag support assembly; The airbag support assembly includes an airbag template (6), which is connected to a support frame (1); The support frame (1) includes two movable support frames (101). A connecting frame (102) is provided on the top of the movable support frame (101). A vertical plate (106) is provided between the connecting frame (102) and the movable support frame (101). A connecting arch frame (104) connected to the connecting frame (102) is sleeved on the outside of the movable support frame (101). A workbench (105) is provided between the two connecting arch frames (104). The movable support frame (101) is an n-shaped frame. The n-shaped frame includes two vertical bars and one horizontal bar. A side plate (107) is provided on the side of one vertical bar facing the other vertical bar. A mounting horizontal plate (103) is provided between the two horizontal bars. The mounting horizontal plate (103) is located between the two vertical plates (106). The airbag support assembly also includes a telescopic rotating arm mechanism (2), an airbag retraction mechanism, and a support assembly. The telescopic rotating arm mechanism (2) includes a coaxial dual-axis motor (21). The coaxial dual-axis motor (21) is located on the top of the mounting horizontal plate (103) and between the two vertical plates (106). The two output shafts of the coaxial dual-axis motor (21) are provided with a transmission shaft (22) that passes through the vertical plate (106) and extends to the outside of the vertical plate (106). The transmission shaft (22) is connected to the vertical plate (106) through a bearing. The two transmission shafts (22) are each provided with a first telescopic rod (23) at opposite ends. The two first telescopic rods (23) are respectively provided on opposite sides of the two vertical plates (106). The output ends of the two first telescopic rods (23) are connected to each other through a connecting horizontal plate (24). The upper surface of the connecting horizontal plate (24) is provided with a mounting hole (25). The airbag winding mechanism includes a winding roller (4) and a guide roller (5). The winding roller (4) and the guide roller (5) are both located between two side plates (107), and the guide roller (5) is located below the winding roller (4). A winding motor (3) is provided on the side of one side plate (107) away from the winding roller (4). The output shaft of the winding motor (3) is connected to the winding roller (4). The airbag template (6) includes a first airbag (61), one end of which is wrapped around the outside of the take-up roller (4), and the other end extends to the top of the connecting horizontal plate (24) and is connected to the connecting horizontal plate (24). The guide roller (5) is arranged on the path of the extension of the first airbag (61) and is in close contact with the first airbag (61). The guide roller (5) is used to guide and support the first airbag (61). The first airbag (61) has a spray hole (63) on the side away from the support frame (1). The spray hole (63) is located above the mounting hole (25) and is connected to the mounting hole (25). The concrete nozzle (9) is located on the lower surface of the connecting plate (24) and extends through the mounting hole (25) to the inside of the spray hole (63). The concrete nozzle (9) is connected to the shotcrete machine through the delivery pipe (7). The first airbag (61) has side holes (62) on both sides. The two side holes (62) are connected to the air inlet pipe (8) and the air extraction pipe (12) respectively. The other end of the air inlet pipe (8) is connected to the air pump, and the other end of the air extraction pipe (12) is connected to the air extraction pump.

2. The concrete airbag formwork for initial tunnel support as described in claim 1, characterized in that: The support assembly includes two sets of second telescopic rods (10). Each of the two connecting arched frames (104) is provided with a set of second telescopic rods (10) on one side. Each set of second telescopic rods (10) includes at least 2N second telescopic rods (10), where N is a positive integer. The 2N second telescopic rods (10) are symmetrically distributed with the upright plate (106) as the center line. The output end of the second telescopic rod (10) is provided with an arc-shaped movable bracket (11). The arc-shaped movable bracket (11) includes an arc plate (111) provided at the output end of the second telescopic rod (10). An opening groove (112) is provided on the side of the arc plate (111) away from the second telescopic rod (10). A rotating roller (113) is provided between the two side walls of the opening groove (112). The rotating roller (113) is in contact with the surface of the first airbag (61) facing the support frame (1).

3. The concrete airbag formwork for initial tunnel support as described in claim 1, characterized in that: The coaxial dual-axis motor (21), the first telescopic rod (23), the winding motor (3), the air pump, the air pump and the second telescopic rod (10) are linked and controlled.

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