Air curtain anchor rod combined support structure and construction method thereof

Abstract

The application belongs to the technical field of initial lining structure of drill and blast tunnel, and particularly relates to a gas curtain anchor rod combined support structure and a construction method thereof. The anchor rod unit protrudes from the surface of the initial lining structure, and the gas curtain passes through the anchor rod unit and is fixedly connected with the anchor rod unit. The air bag is arranged between the spray mixing structure and the gas curtain, and the air bag is inflated and expanded to press the initial lining structure and the gas curtain, the gas curtain provides a counterforce for the air bag unit, and a uniform support pressure is generated on the initial lining structure. The air bags on the same tunnel cross section are connected in series into a ring-shaped air bag loop through an inflation pipeline, and multiple ring-shaped air bag loops are connected into an air bag system through an inflation pipeline, and are connected with an air compressor to inflate and pressurize the air bag system. The support structure can apply an additional uniform active support force to the initial lining structure, increase the bearing capacity and safety of the initial lining combined structure, and prolong the working time of the support structure. The internal pressures of each ring-shaped air bag loop are independent of each other, and the active support force can be dynamically adjusted in real time according to the geological conditions of the tunnel, and the monitoring data of the convergence deformation in construction.

Description

Technical Field

[0001] This invention belongs to the technical field of initial lining structure for drill-and-blast tunnels, specifically relating to an initial lining structure for drill-and-blast tunnels using a combination of airbags, air curtains, and anchor bolts, and its construction method. Background Technology

[0002] Drill-and-blast method is a commonly used construction method in cut-and-cover tunnel excavation, widely applied in tunnel projects due to its advantages such as low cost, low construction difficulty, strong adaptability to geological formations, and long history of application. The primary lining structure of drill-and-blast tunnels often employs a flexible support structure of shotcrete + steel mesh + anchor bolts, closely integrated with the tunnel excavation section and perfectly conforming to its shape, allowing for a certain degree of deformation of the surrounding rock. After the surrounding rock undergoes deformation, friction is generated between the anchor bolts and the surrounding rock, providing support and maximizing the load-bearing capacity of the support structure; therefore, it is a passive support structure. However, this flexible passive support structure may encounter problems such as excessive tunnel deformation, insufficient support strength, and localized failure of the support structure when encountering adverse geological conditions not revealed in the geological survey data (such as rock bursts, rockfalls, fractured zones, and karst development zones), even leading to safety accidents and casualties. Therefore, the secondary lining structure of highway and railway tunnels must closely follow the primary lining structure, and be constructed promptly after the primary lining structure has stabilized, sharing the pressure of the surrounding rock with the primary lining structure.

[0003] However, the secondary lining structure in hydraulic tunnels often cannot be constructed simultaneously with the primary lining. Because the internal secondary lining of a hydraulic tunnel is a water-bearing structure, it is typically designed with a circular cross-section for low flow resistance, while the external primary lining structure is designed with a curved or straight arched cross-section for easier excavation and construction. Once the internal circular secondary lining structure is completed and cured, it cannot be used as an access route for tunnel construction vehicles. To ensure smooth traffic flow within the tunnel, the secondary lining must be constructed in a retreating sequence after the primary lining structure is completed, resulting in the secondary lining not being able to be constructed simultaneously with the tunnel face. Therefore, the working time of the primary lining structure is much longer than that of highway and railway tunnels. Depending on the tunnel length, the working time of the primary lining structure often needs to reach more than two years. For primary lining structures with such long service lives, the probability of structural defects, large tunnel deformation, or even roof collapse during service life increases significantly. Summary of the Invention

[0004] To address the above technical problems, this invention proposes an air curtain anchor bolt combined support structure and its construction method, aiming to overcome the shortcomings of existing flexible passive primary lining structures where the primary lining bearing capacity is low, leading to large deformation of the surrounding rock.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] An air curtain anchor bolt assembly primary lining structure includes: an anchor bolt unit, the end of which extends beyond the surface of the primary lining structure and is exposed at a certain distance; several bolt connection substructures are provided on the exposed part of the bolt, the inner bolt connection substructure includes a washer and a nut, and the outer bolt connection substructure includes a washer and a limiting double nut; the anchor bolt unit passes through the air curtain, the air curtain is located inside the limiting double nut and the washer, and the air curtain is fixed to the end of the anchor bolt unit after the limiting double nut is tightened.

[0007] Furthermore, airbag units are installed between the primary lining structure and the air curtain, and these airbag units are fixed to the surface of the primary lining structure. After inflation, the airbag units press against the primary lining structure and the air curtain, causing the air curtain to expand accordingly. The air curtain is fixed and restrained by the anchor bolt units, thus providing a reaction force to the airbag units and transmitting the airbag pressure to the primary lining structure, generating a uniformly distributed pressure perpendicular to its surface. The airbag units are placed between the anchor bolt units, and their inflated planar dimensions do not exceed the planar spacing of the anchor bolt units.

[0008] Furthermore, multiple airbag units on the same tunnel cross section are connected in series through circumferential inflation pipelines to form a ring airbag circuit. Each ring airbag circuit is equipped with a pressure gauge and a pipeline switch. Multiple ring airbag circuits are connected in parallel through longitudinal inflation pipelines to form an airbag system, which is connected to an air compressor.

[0009] Furthermore, the pipeline switch includes an air intake pipeline switch and an exhaust pipeline switch. The air intake pipeline switch is installed at the arch foot on one side of the tunnel, and the exhaust pipeline switch is installed at the corresponding arch foot on the other side of the tunnel.

[0010] Furthermore, the internal pressure of each annular airbag circuit is independent. A preset pressure P2 can be determined for each annular airbag circuit based on the different surrounding rock grades and geological conditions at the tunnel cross-section. A pressure gauge monitors the internal pressure P1 of each annular airbag circuit in real time. When the internal pressure P1 deviates from the preset pressure P2, the internal pressure P1 is brought back to the preset pressure P2 by opening and closing the intake and exhaust pipe switches. Simultaneously, if the convergence deformation in a certain tunnel section is found to be continuously increasing, the preset pressure P2 of the annular airbag circuit in that tunnel section can be increased, thereby increasing the internal pressure P1 and enhancing the support strength of that tunnel section.

[0011] Correspondingly, the present invention also provides a construction method for an air curtain anchor bolt combined support structure, comprising the following steps:

[0012] S1: Construction of the tunnel initial lining structure and anchor bolt unit, tighten the inner bolt connection substructure of the anchor bolt unit, and fix the anchor bolt unit on the surface of the initial lining structure;

[0013] S2: Install the airbag unit;

[0014] S3: Set round holes on the air curtain, with the hole diameter being the same as the diameter of the anchor bolt body, and the spacing between the round holes being the same as the distribution spacing of the anchor bolt units; the air curtain passes through the anchor bolt unit and is located inside the limiting double nut and the washer. After tightening the limiting double nut, fix the air curtain at the end of the anchor bolt unit.

[0015] S4: Based on the different grades of surrounding rock and geological conditions, determine the preset pressure for each annular airbag circuit, open the air intake pipe switch, close the exhaust pipe switch, and inflate and pressurize the airbag unit through the air compressor until the internal pressure is close to the preset pressure; after inflation is completed, close the air intake pipe switch of the annular airbag circuit.

[0016] S5: Open the exhaust pipe switch to release the pressure of the airbag unit; sequentially remove the outer bolt connection substructure of the anchor unit, air curtain, inflation pipe, pressure gauge, pipe switch and airbag unit and recycle them;

[0017] S6: Construction of the secondary lining structure of the tunnel, with the portion of the anchor bolt protruding from the primary lining structure and anchored into the secondary lining structure.

[0018] Furthermore, the installation of the airbag unit specifically includes the following steps:

[0019] S21: Airbag units are placed between the anchor bolt unit intervals and the airbag units are fixed to the surface of the initial lining structure;

[0020] S22: The airbag units on the same tunnel cross section are connected in series to form a ring airbag circuit through a circumferential inflation pipeline. At the arch foot on one side of the tunnel, it is connected in series with a pressure gauge and an air intake pipeline switch, and at the arch foot on the other side of the tunnel, it is connected in series with an exhaust pipeline switch.

[0021] S23: The pressure gauge, air intake pipe switch, and exhaust pipe switch shall be installed at the tunnel arch foot using fixed brackets;

[0022] S24: The annular airbag circuits for different tunnel cross sections are connected by longitudinal inflation pipelines at the arch foot and connected to an air compressor.

[0023] Compared with the prior art, the beneficial effects of the technical solution of this invention are:

[0024] By combining the design of air curtain and airbag units, along with the fixing effect of anchor bolt units, the inflation pressure of the airbags is transformed into a uniformly distributed pressure perpendicular to the primary lining structure, forming an active support system. The linkage control of pressure gauges and pipeline switches allows for real-time monitoring and dynamic adjustment of the internal pressure of the annular airbag circuit, ensuring it matches the preset pressure. This solves the problem of insufficient load-bearing capacity in traditional flexible passive support structures, reduces deformation of the primary lining structure and surrounding rock, and is particularly suitable for hydraulic tunnels with complex surrounding rock conditions or those requiring long-term service, thus reducing the risk of structural failure.

[0025] The pressure of each annular airbag circuit is independently controlled, and the preset pressure can be set according to the different surrounding rock grades and geological conditions of different tunnel cross sections. When the convergence deformation of a certain section is continuously increased, the preset pressure of that section can be increased in a targeted manner to quickly enhance the local support strength and improve the flexibility and safety of the support system.

[0026] The inflated airbag unit and the air curtain together form a continuous sealing layer, which effectively blocks water leakage, falling pieces and soil from the surface of the primary lining, greatly improves the construction environment inside the tunnel, reduces safety hazards during construction, and reduces the cleaning and repair costs of the subsequent secondary lining structure.

[0027] Except for the anchor bolt units and the initial lining structure, the air curtain, airbag units, inflation pipelines, and control components can all be disassembled, recycled, and reused. This reduces material waste and improves the economic efficiency of the project, making it particularly suitable for long tunnels or complex geological sections requiring multiple supports. Attached Figure Description

[0028] Figure 1 This is a tunnel cross-sectional layout diagram for the construction stage S1 of a preferred embodiment of the present invention;

[0029] Figure 2 This is a tunnel cross-sectional layout diagram for construction stage S2 of a preferred embodiment of the present invention;

[0030] Figure 3 This is a tunnel cross-sectional layout diagram for construction stage S3 of a preferred embodiment of the present invention;

[0031] Figure 4 This is a tunnel cross-sectional layout diagram for construction stage S4 of a preferred embodiment of the present invention;

[0032] Figure 5 This is a tunnel cross-sectional layout diagram for construction stage S6 of a preferred embodiment of the present invention;

[0033] Figure 6 This is a partial detailed view of the airbag unit before it is inflated in a preferred embodiment of the present invention;

[0034] Figure 7 This is a partial detailed view of the airbag unit after inflation in a preferred embodiment of the present invention;

[0035] Figure 8 This is a detailed diagram showing the connection between the airbag unit and various components at the arch foot in a preferred embodiment of the present invention; wherein... Figure 8 (a) is a detailed diagram of the airbag unit connection at the left arch foot; Figure 8 (b) is a detailed diagram of the airbag unit connection at the right arch foot;

[0036] Figure 9 This is a plan view showing the layout of the inflated airbag unit along the inner surface of the tunnel.

[0037] Figure 10 A schematic diagram of the piping connection structure for controlling multiple airbag units in different annular airbag circuits of an air compressor.

[0038] The markings in the diagram are as follows: 1: Surrounding rock; 2: Primary lining structure; 3: Anchor bolt unit; 4: Airbag unit; 5a: Pad; 5b: Nut; 5c: Limiting double nut; 6a: Circumferential inflation pipeline; 6b: Longitudinal inflation pipeline; 7: Air curtain; 8: Fixed support; 9: Secondary lining; 10: Pressure gauge; 11: Pipeline switch; 11a: Inlet pipeline switch; 11b: Exhaust pipeline switch; 12: Air compressor; 13: Circumferential airbag circuit; 14a: Tunnel transverse; 14b: Tunnel longitudinal. Detailed Implementation

[0039] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0040] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions are omitted in the drawings.

[0041] To increase the bearing capacity, extend the working time, and enhance the structural safety of traditional flexible passive support structures, this invention proposes an air curtain anchor bolt combined primary lining structure. This structure adds an airbag + air curtain combined active support structure to the traditional flexible passive support structure, making it particularly suitable for tunnel support in adverse geological sections and for primary lining structures in hydraulic tunnels that require ultra-long-term service.

[0042] See Figure 6 and Figure 7 As shown, in a preferred embodiment of the present invention, the end of the anchor bolt unit 3 protrudes 30cm from the surface of the initial lining structure 2. The bolt body has external threads, and the initial lining structure 2 includes a sprayed concrete layer, a steel mesh, a steel arch frame, etc. Two bolt connection substructures are provided on the exposed part of the bolt body. The inner bolt connection substructure consists of a washer 5a and a nut 5b, and the outer bolt connection substructure consists of a washer 5a and a limiting double nut 5c.

[0043] The air curtain 7 has circular holes with the same diameter as the anchor bolt unit 3, and the spacing between the holes is the same as the distribution spacing of the anchor bolt units 3. The air curtain 7 passes through the anchor bolt unit 3 and is located inside the limiting double nut 5c and the washer 5a. After tightening the limiting double nut 5c, the air curtain 7 is fixed to the end of the anchor bolt unit 3.

[0044] The airbag unit 4 is positioned between the primary lining structure 2 and the air curtain 7. Before inflation, it is a flat square and fixed to the surface of the primary lining structure 2; after inflation, it expands into a rounded square, pressing the primary lining structure 2 and the air curtain 7 together, causing the air curtain 7 to expand accordingly. The air curtain 7 is restricted at the anchor bolt unit 3 by the limiting double nuts 5c, preventing it from displacing towards the inside of the tunnel. This provides a reaction force to the airbag unit 4, transferring the airbag pressure to the primary lining structure 2 and generating a uniformly distributed pressure perpendicular to the primary lining structure 2. The air curtain 7 transfers the airbag inflation pressure to the anchor bolt unit 3, converting it into axial tension in the anchor bolt, which is balanced by the friction between the anchor bolt and the surrounding rock.

[0045] The spacing between the airbag units 4 is consistent with the distribution spacing of the anchor bolt units 3, that is, one airbag unit 4 is placed between every two anchor bolts 3. The planar dimension of the airbag unit 4 after inflation does not exceed the distribution spacing of the anchor bolt units 3.

[0046] See Figure 8 a and Figure 8 As shown in Figure b, multiple airbag units 4 on the same tunnel cross section are connected in series through a circumferential inflation pipe 6a to form a ring-shaped airbag circuit 13. This circuit is connected in series with a pressure gauge 10 and an intake pipe switch 11a at the left arch foot of the tunnel, and in series with an exhaust pipe switch 11b at the right arch foot of the tunnel. The pressure gauge 10 and the pipe switches 11a and 11b are fixed to the surface of the primary lining structure 2 by a fixed bracket 8.

[0047] See Figure 9 and Figure 10 As shown, multiple annular airbag circuits 13 are connected in parallel at the left arch foot of the tunnel by longitudinal inflation pipes 6b to form an airbag system, and are connected to an air compressor 12, which provides pressure to the airbag units 4 in each annular airbag circuit 13. The internal pressure of each annular airbag circuit 13 is independent of each other.

[0048] exist Figure 10In this system, a preset pressure P2 is determined for each annular airbag circuit 13 based on the different surrounding rock grades and geological conditions at the tunnel cross-section. A pressure gauge 10 monitors the internal pressure P1 of each annular airbag circuit 13 in real time and controls the internal pressure P1 through the air intake switch 11a and the exhaust switch 11b at the tunnel arch foot. When the internal pressure P1 ≤ the preset pressure P2, the left air intake switch 11a is opened to replenish the pressure using the air compressor 12, and then the air intake switch 11a is closed after the pressure replenishment is complete. When the internal pressure P1 > the preset pressure P2, the right exhaust switch 11b is opened to release air appropriately, and then the exhaust switch 11b is closed after the air release is complete.

[0049] During tunnel construction, the convergence deformation of anchor bolt unit 3 and initial lining structure 2 is monitored and measured. When the convergence deformation in a certain tunnel section is found to be increasing continuously, the preset pressure P2 of the annular airbag circuit 13 in that tunnel section can be increased, and the internal pressure P1 can be increased to enhance the support strength of that tunnel section.

[0050] Figures 1-5 The diagram shows the tunnel cross-sectional layout at each construction stage of a preferred embodiment of the present invention.

[0051] Figure 1 The diagram shows construction stage S1: After the tunnel excavation is completed, the initial lining structure 2 and the anchor bolt unit 3 are constructed. The inner bolts of the anchor bolt unit 3 are tightened to connect the substructure, and the anchor bolt unit 3 is fixed to the surface of the initial lining structure 2.

[0052] Figure 2 The diagram shows construction phase S2: installation of airbag unit 4, which includes the following steps:

[0053] S21: An airbag unit 4 is placed between every two anchor bolt units 3, and the airbag unit 4 is fixed to the surface of the primary lining structure 2.

[0054] S22: The airbag units 4 on the same tunnel cross section are connected in series to form a ring airbag circuit 13 through the circumferential inflation pipe 6a. It is connected in series with the pressure gauge 10 and the air intake pipe switch 11a at the left arch foot of the tunnel, and connected in series with the exhaust pipe switch 11b at the right arch foot of the tunnel.

[0055] S23: The pressure gauge 10 and the air intake and exhaust pipe switches 11a and 11b are installed at the tunnel arch foot using a fixed bracket 8.

[0056] S24: The annular airbag circuit 13 of different tunnel cross sections is connected by a longitudinal inflation pipeline 6b at the arch foot and connected to the air compressor 12.

[0057] Figure 3The diagram shows construction stage S3: Circular holes are made on the air curtain 7, with the hole diameter matching the diameter of the anchor bolt body, and the spacing between the circular holes matching the distribution spacing of the anchor bolt units 3. The air curtain 7 passes through the anchor bolt unit 3 and is located inside the limiting double nut 5c and the washer 5a. After tightening the limiting double nut 5c, the air curtain 7 is fixed to the end of the anchor bolt unit 3.

[0058] Figure 4 The diagram shows construction stage S4: Based on the different grades of surrounding rock and geological conditions, a preset pressure P2 is determined for each annular airbag circuit 13. The air intake pipe switch 11a is opened, and the exhaust pipe switch 11b is closed. The airbag unit 4 is inflated and pressurized by the air compressor 12 until the internal pressure P1 is close to the preset pressure P2. After inflation is completed, the air intake pipe switch 11a of the annular airbag circuit 13 is closed.

[0059] S5 to S6 represent the dismantling and recycling construction stages of the support system of this invention.

[0060] S5: Open the exhaust pipe switch 11b to release the pressure of the airbag unit 4; then remove the outer bolt connection substructure of the anchor unit, the air curtain 7, the inflation pipes 6a and 6b, the pressure gauge 10, the pipe switches 11a and 11b, and the airbag unit 4 in sequence and retrieve them.

[0061] Figure 5 The diagram shows construction stage S6: construction of tunnel secondary lining 9, with the portion of anchor bolt unit 3 protruding from the primary lining structure 2 anchored into tunnel secondary lining 9.

[0062] This support structure can apply additional uniform active support force to the primary lining structure, increase the bearing capacity and safety of the primary lining composite structure, and extend the working time of the support structure; the internal pressure of each annular airbag circuit is independent of each other, and its active support force can be dynamically adjusted in real time according to the geological conditions of the tunnel and the monitoring data of convergence deformation during construction.

[0063] The above embodiments are merely preferred technical solutions of the present invention. Those skilled in the art should understand that modifications to the technical solutions or parameters in the embodiments without departing from the principles and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A construction method for an air curtain anchor bolt combined support structure, characterized in that, The anchor bolt unit (3) has its end extending beyond the surface of the initial lining structure (2) and exposed at a certain distance. Several bolt connection substructures are provided on the exposed part of the bolt. The inner bolt connection substructure includes a pad (5a) and a nut (5b), and the outer bolt connection substructure includes a pad (5a) and a limiting double nut (5c). The anchor bolt unit (3) passes through the air curtain (7). The air curtain (7) is located inside the limiting double nut (5c) and the pad (5a). After tightening the limiting double nut (5c), the air curtain (7) is fixed at the end of the anchor bolt unit (3). An airbag unit (4) is provided between the primary lining structure (2) and the air curtain (7), and the airbag unit (4) is fixed on the surface of the primary lining structure (2); after the airbag unit (4) is inflated, it presses the primary lining structure (2) and the air curtain (7) together, causing the air curtain (7) to expand accordingly; the airbag unit (4) is placed between the anchor bolt units (3), and its inflated planar size does not exceed the planar arrangement spacing of the anchor bolt units (3); The construction steps for the air curtain anchor bolt combined support structure are as follows: S1: Construct the tunnel lining structure (2) and anchor unit (3), tighten the inner bolt connection substructure of the anchor unit (3), and fix the anchor unit (3) on the surface of the lining structure (2); S2: Install the airbag unit (4); S3: A circular hole is provided on the air curtain (7), the diameter of which is the same as the diameter of the rod body, and the spacing between the circular holes is the same as the distribution spacing of the anchor rod unit (3); the air curtain (7) passes through the anchor rod unit (3) and is located inside the limiting double nut (5c) and the pad (5a). After tightening the limiting double nut (5c), the air curtain (7) is fixed at the end of the anchor rod unit (3); S4: Based on the different grades of surrounding rock and geological conditions, determine the preset pressure P2 for each annular airbag circuit (13), open the air intake pipe switch (11a), close the exhaust pipe switch (11b), and inflate and pressurize the airbag unit (4) through the air compressor (12) until the internal pressure P1 is close to the preset pressure P2; after inflation is completed, close the air intake pipe switch (11a) of the annular airbag circuit (13). S5: Open the exhaust pipe switch (11b) to exhaust and depressurize the airbag unit (4); remove the outer bolt connection substructure of the anchor unit (3), the air curtain (7), the inflation pipe (6a, 6b), the pressure gauge (10), the pipe switch (11) and the airbag unit (4) in sequence and recycle them; S6: Construction of the secondary lining structure (9) of the tunnel, with the part of the anchor bolt protruding from the primary lining structure (2) anchored into the secondary lining structure (9).

2. The construction method of the air curtain anchor bolt combined support structure according to claim 1, characterized in that, Multiple airbag units (4) on the same tunnel cross section are connected in series to form an annular airbag circuit (13) through a circumferential inflation pipeline (6a). Each annular airbag circuit (13) is equipped with a pressure gauge (10) and a pipeline switch (11). Multiple annular airbag circuits (13) are connected in parallel through a longitudinal inflation pipeline (6b) to form an airbag system and are connected to an air compressor (12).

3. The construction method of the air curtain anchor bolt combined support structure according to claim 2, characterized in that, The pipeline switch (11) includes an air intake pipeline switch (11a) and an exhaust pipeline switch (11b). The air intake pipeline switch (11a) is installed at the arch foot on one side of the tunnel, and the exhaust pipeline switch (11b) is installed at the corresponding arch foot on the other side of the tunnel.

4. The construction method of the air curtain anchor bolt combined support structure according to claim 2, characterized in that, The internal pressure of each annular airbag circuit (13) is independent of each other. The preset pressure P2 of each annular airbag circuit (13) can be determined according to the different surrounding rock grades and geological conditions at the tunnel cross section. The pressure gauge (10) monitors the internal pressure P1 of each annular airbag circuit (13) in real time. When the internal pressure P1 deviates from the preset pressure P2, the internal pressure P1 is brought back to the preset pressure P2 by opening and closing the air intake pipe switch (11a) and the exhaust pipe switch (11b). At the same time, when it is found that the convergence deformation in a certain tunnel section continues to increase, the preset pressure P2 of the annular airbag circuit (13) in that tunnel section can be increased to increase the internal pressure P1, so as to enhance the support strength of the tunnel section.

5. The construction method of the air curtain anchor bolt combined support structure according to claim 1, characterized in that, The installation of the airbag unit includes the following steps: S21: An airbag unit (4) is placed between the anchor bolt units (3) and the airbag unit (4) is fixed on the surface of the primary lining structure (2); S22: The airbag units (4) on the same tunnel cross section are connected in series to form a ring airbag circuit (13) through the circumferential inflation pipeline (6a). It is connected in series with the pressure gauge (10) and the air inlet pipeline switch (11a) at the arch foot on one side of the tunnel, and connected in series with the exhaust pipeline switch (11b) at the arch foot on the other side of the tunnel. S23: The pressure gauge (10), the air intake pipe switch (11a), and the exhaust pipe switch (11b) are installed at the tunnel arch foot using fixed brackets; S24: The annular airbag circuit (13) of different tunnel cross sections is connected by a longitudinal inflation pipeline (6b) at the arch foot and connected to an air compressor (12).

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