An asymmetric non-mid-wall connected arch tunnel support system

Abstract

The utility model discloses an asymmetric non -middle wall connected arch tunnel support system relates to tunnel support technical field, including connected arch tunnel first -pass hole initial support, connected arch tunnel first -pass hole initial support includes I20a type steel arch frame, inside phi 8 steel bar net, outside phi 8 steel bar net, steel arch frame connecting reinforcing steel bar, big arch foot reinforcing cage, big arch foot steel arch frame triangle bracing structure, big arch foot steel arch frame connecting steel sheet and stiffened steel plate, through the first -pass hole initial support of setting, first -pass hole initial support adopts I20a type steel arch frame, inside phi 8 steel bar net, outside phi 8 steel bar net, steel arch frame connecting reinforcing steel bar, big arch foot reinforcing cage, big arch foot steel arch frame triangle bracing structure, connecting steel plate and stiffened steel plate, form high -strength, high rigid support system, effectively disperses the surrounding rock pressure, reduces local damage, and system anchor rod and radial injection grouting small catheter consolidate surrounding rock through injection grouting, further enhances the stability of surrounding rock.

Description

Technical Field

[0001] This utility model relates to the field of tunnel support technology, specifically to an asymmetric arch tunnel support system without a central wall. Background Technology

[0002] In the construction of mountain highways, some special sections are inevitably encountered, such as narrow terrain, difficult wiring, or tunnel entrances and exits restricted by large bridge structures. In these cases, traditional separated tunnels will hardly meet the requirements of the route layout. Compared with tunnels with small clearance, arch tunnels can further reduce the axis spacing, reduce the land area occupied, and increase the freedom of choosing the location of the tunnel entrance and external wiring.

[0003] Due to the complexity of traditional arch tunnel structures, current construction methods often employ traditional approaches such as the three-pilot tunnel method or the central pilot tunnel method. Construction of the main tunnel must proceed only after the pilot tunnels have been excavated and supported, resulting in numerous construction steps, extensive temporary support, and limitations on large-scale mechanized construction. This leads to long construction periods and high project costs. Furthermore, the numerous construction procedures result in frequent structural stress transitions and increased disturbance to the surrounding rock, leading to numerous construction control challenges and making the tunnel prone to defects such as poor integrity of the central wall, cracking of the lining structure, and water leakage.

[0004] With technological advancements and improved construction techniques, design and construction schemes must not only meet structural safety requirements but also consider reducing project costs and shortening construction periods. Therefore, tunnels without central walls, characterized by simple procedures, minimal disturbance to the surrounding rock, and the ability to shorten construction time and reduce costs, are increasingly attracting the attention of tunnel engineering technicians. Based on the aforementioned research and combined with existing technologies, this paper proposes an asymmetric support system for tunnels without central walls to address the aforementioned issues. Utility Model Content

[0005] The purpose of this invention is to provide an asymmetric arch tunnel support system without a central wall to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] An asymmetric arch tunnel support system without a central wall includes initial support for the pilot tunnel of the arch tunnel. The initial support for the pilot tunnel of the arch tunnel includes an I20a type steel arch frame, an inner φ8 steel mesh, an outer φ8 steel mesh, steel arch frame connecting steel bars, a large arch foot steel cage, a large arch foot steel arch frame triangular bracing structure, a large arch foot steel arch frame connecting steel plate, and a stiffening steel plate.

[0008] The anchor bolts for the pilot tunnel system of the arch tunnel are 600cm long and Φ4.2cm radial grouting pipes, which are installed on the rock-clamped side of the pilot tunnel.

[0009] The initial support arch foot on the rock-clamped side of the pilot tunnel of the continuous arch tunnel is composed of a large arch foot steel reinforcement cage, a large arch foot steel arch frame triangular brace structure, connecting steel plates and stiffening steel plates.

[0010] The bottom of the pilot tunnel is provided with an initial support arch structure for the pilot tunnel of the connecting arch tunnel. Above the arch structure is a secondary lining arch structure for the pilot tunnel of the connecting arch tunnel. Above the secondary lining arch structure for the pilot tunnel of the connecting arch tunnel is a filling structure for the arch invert of the pilot tunnel of the connecting arch tunnel.

[0011] The secondary lining arch structure of the first tunnel of the arch tunnel gradually changes from 70cm thick on the side of the interbedded rock to 45cm thick on the side away from the interbedded rock. The initial support structure of the second tunnel of the arch tunnel adopts I18 type steel arch frame. The anchor rods of the second tunnel system of the arch tunnel adopt 300cm long Φ4.2cm inclined 45° grouting pipe. The advanced grouting small pipe of the second tunnel of the arch tunnel is used for advanced grouting reinforcement of the second tunnel. The tie anchor cables of the interbedded rock of the arch tunnel are connected to the first tunnel and the second tunnel through PVC protective sleeve. The secondary lining arch structure of the second tunnel of the arch tunnel gradually changes from 65cm thick on the side of the interbedded rock to 45cm thick on the side away from the interbedded rock.

[0012] Furthermore, the outer side of the initial support arch foot on the rock-clamped side of the pilot tunnel of the connecting arch tunnel is coated with a superhydrophobic nano-coating, which is applied by spraying and has a thickness of 5-8μm.

[0013] Furthermore, the I20a type steel arch frame of the initial support of the pilot tunnel of the continuous arch tunnel is fixedly connected to the steel reinforcement cage of the large arch foot through M20×70 bolt groups and steel arch frame connecting steel bars. The connecting steel plate and stiffening steel plate of the triangular brace structure of the large arch foot steel arch frame are connected to the I20a type steel arch frame through M20×70 bolt groups.

[0014] Furthermore, an expansion joint is reserved between the secondary lining invert arch structure and the secondary lining arch ring structure of the first tunnel of the continuous arch tunnel, and the width of the expansion joint is 5cm.

[0015] Furthermore, the two ends of the rock-clamped tie-cable in the arch tunnel are respectively anchored in the initial support structure of the first tunnel and the second tunnel. The rock-clamped tie-cable in the arch tunnel is protected by a PVC protective sleeve for the tie-cable. The prestress locking value of the rock-clamped tie-cable in the arch tunnel is determined based on the tunnel surrounding rock pressure.

[0016] Furthermore, both the radial grouting guide pipe in the initial tunnel and the advanced grouting guide pipe in the subsequent tunnel of the connecting arch tunnel adopt Φ4.2cm grouting guide pipes. The radial grouting guide pipe is 600cm long, and the advanced grouting guide pipe is 300cm long. The radial grouting guide pipe is installed on the side of the interbedded rock in the initial tunnel to reinforce the surrounding rock, and the advanced grouting guide pipe is used for advanced grouting reinforcement in the subsequent tunnel.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] The initial support system for the pilot tunnel, consisting of I20a type steel arch frame, inner φ8 steel mesh, outer φ8 steel mesh, steel arch frame connecting steel bars, large arch foot steel cage, large arch foot steel arch frame triangular bracing structure, connecting steel plates and stiffening steel plates, forms a high-strength and high-rigidity support system that effectively disperses the surrounding rock pressure and reduces local damage.

[0019] The system anchor bolts and radial grouting pipes reinforce the surrounding rock through grouting, further enhancing the stability of the surrounding rock. The initial support arch foot of the middle rock side provides additional support force, enhancing the overturning resistance of the wall foot. The initial support invert arch structure of the pilot tunnel of the continuous arch tunnel and the secondary lining invert arch structure of the pilot tunnel of the continuous arch tunnel adopt a gradual thickness design, which optimizes the structural stress, increases the cross-sectional area of ​​the wall foot, and improves the bending strength.

[0020] The initial support structure and system anchors of the secondary tunnel provide reliable initial support, reducing the impact on the primary tunnel. Pre-grouting small guide pipes are used for pre-grouting reinforcement of the secondary tunnel, minimizing the impact of construction on the primary tunnel. Inter-rock tie-bar anchors connect the primary and secondary tunnels via PVC protective sleeves, providing additional restraint and enhancing the stability of the inter-rock. The synergistic effect of these structural components not only improves the overall stability of the tunnel but also optimizes the construction process, reduces engineering costs, and provides a reliable solution for tunnel construction under complex geological conditions. Attached Figure Description

[0021] Figure 1 This is a diagram of the asymmetric arch tunnel support system without a central wall according to this utility model;

[0022] Figure 2 This is a detailed drawing of the arch foot of the initial support for the pilot tunnel of the multi-arch tunnel according to this utility model.

[0023] Figure 3 This is a detailed drawing of the steel arch frame triangular brace for the initial support of the main arch foot of the pilot tunnel of the present invention.

[0024] Figure 4 This is a cross-sectional view of the initial support of the pilot tunnel of the multi-arch tunnel according to this utility model.

[0025] Figure 5This is a detailed drawing of the rock-clamped anchor cable in the arch tunnel of this utility model.

[0026] In the diagram: 1. Initial support of the pilot tunnel of the twin-arch tunnel; 2. Anchor bolts of the pilot tunnel system of the twin-arch tunnel; 3. Radial grouting guide pipes for interbedded rock in the pilot tunnel of the twin-arch tunnel; 4. Large arch foot of the initial support for the interbedded rock side of the pilot tunnel of the twin-arch tunnel; 5. Invert arch structure of the initial support of the pilot tunnel of the twin-arch tunnel; 6. Invert arch structure of the secondary lining of the pilot tunnel of the twin-arch tunnel; 7. Invert arch filling structure of the pilot tunnel of the twin-arch tunnel; 8. Arch ring structure of the secondary lining of the pilot tunnel of the twin-arch tunnel; 9. Initial support structure of the rear tunnel of the twin-arch tunnel; 10. Anchor bolts of the pilot tunnel system of the twin-arch tunnel; 11. Advance grouting guide pipes for the rear tunnel of the twin-arch tunnel; 12. Tie anchor cables for interbedded rock in the twin-arch tunnel; 13. Invert arch structure of the initial support of the rear tunnel of the twin-arch tunnel; 14. Invert arch structure of the secondary lining of the rear tunnel of the twin-arch tunnel; 15. Invert arch filling of the rear tunnel of the twin-arch tunnel. 16. Secondary lining arch structure of the rear tunnel of the twin-arch tunnel; 17. Reinforcing cage for the main arch foot of the initial support of the twin-arch tunnel; 18. Triangular bracing structure of the steel arch frame for the main arch foot of the initial support of the twin-arch tunnel; 19. I20a steel arch frame for the initial support of the twin-arch tunnel; 20. Connecting steel plate for the steel arch frame for the main arch foot of the initial support of the twin-arch tunnel; 21. Stiffening steel plate for the main arch foot of the initial support of the twin-arch tunnel; 22. M20×70 bolt set; 23. φ8 steel mesh on the inner side of the initial support of the twin-arch tunnel; 24. φ8 steel mesh on the outer side of the initial support of the twin-arch tunnel; 25. Connecting steel bars for the steel arch frame of the initial support of the twin-arch tunnel; 26. Surrounding rock of the tunnel; 27. Prestressed tie anchor cable; 28. PVC protective sleeve for prestressed tie anchor cable. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] In one typical implementation of this application, please refer to Figures 1-5 An asymmetric arch tunnel support system without a central wall includes an initial support 1 for the pilot tunnel of the arch tunnel. The initial support 1 for the pilot tunnel of the arch tunnel includes an I20a type steel arch frame 19, an inner φ8 steel mesh 23, an outer φ8 steel mesh 24, steel arch frame connecting steel bars 25, a large arch foot steel cage 17, a large arch foot steel arch frame triangular bracing structure 18, a large arch foot steel arch frame connecting steel plate 20, and a stiffening steel plate 21.

[0029] Anchor bolt 2 of the pilot tunnel system of the arch tunnel adopts a 600cm long Φ4.2cm radial grouting pipe and is installed on the side of the interbedded rock in the pilot tunnel. Radial grouting small pipe 3 of the interbedded rock in the pilot tunnel of the arch tunnel is used to reinforce the surrounding rock.

[0030] The initial support arch foot 4 on the side of the interlocking rock in the first tunnel of the continuous arch tunnel is composed of a large arch foot steel cage 17, a large arch foot steel arch frame triangular brace structure 18, a connecting steel plate 20 and a stiffening steel plate 21.

[0031] The bottom of the pilot tunnel is provided with an initial support arch structure 5 for the pilot tunnel of the connecting arch tunnel. Above the arch structure 5 is a secondary lining arch structure 6 for the pilot tunnel of the connecting arch tunnel. Above the secondary lining arch structure 6 of the pilot tunnel of the connecting arch tunnel is a filling structure 7 for the pilot tunnel of the connecting arch tunnel.

[0032] The secondary lining arch structure 8 of the first tunnel of the continuous arch tunnel gradually changes from 70cm thick on the side of the middle rock to 45cm thick on the side away from the middle rock. The initial support structure 9 of the second tunnel of the continuous arch tunnel adopts I18 type steel arch frame. The anchor rod 10 of the second tunnel system of the continuous arch tunnel adopts 300cm long Φ4.2cm inclined 45° grouting pipe.

[0033] The small guide pipe 11 for grouting ahead of the rear tunnel of the arch tunnel is used for grouting ahead of the rear tunnel for reinforcement. The rock-interlocking anchor cable 12 in the arch tunnel is connected to the first tunnel and the rear tunnel through the PVC protective sleeve 28.

[0034] The invert arch structure 13 of the initial support of the rear tunnel of the continuous arch tunnel is located at the bottom of the rear tunnel and is connected to the initial support structure 9 of the rear tunnel. It is used to support the surrounding rock at the bottom of the rear tunnel and provide initial support strength.

[0035] The secondary lining invert arch structure 14 of the subsequent tunnel of the continuous arch tunnel is located above the initial support invert arch structure 13. It is connected by steel bars and works together with the initial support invert arch structure 13 to provide structural strength for the secondary lining. Its thickness is 45cm and it adopts a conventional structural design.

[0036] The invert arch filling structure 15 of the rear tunnel of the continuous arch tunnel fills the space above the secondary lining invert arch structure 14 to fill the gaps in the invert arch and ensure the integrity and stability of the structure.

[0037] Through the above structural design, the inverted arch of the rear tunnel can effectively disperse the pressure of the surrounding rock, reduce the impact of the deformation of the surrounding rock on the structure during construction, and improve the overall stability and durability of the rear tunnel. It works in conjunction with the support system of the first tunnel to achieve the overall support effect of the asymmetric arch tunnel without a middle wall.

[0038] The secondary lining arch structure 16 of the rear tunnel of the continuous arch tunnel gradually changes from 65cm thick on the side of the middle rock to 45cm thick on the side away from the middle rock.

[0039] Other auxiliary structures, such as M20×70 bolt group 22, are used to connect the steel arch frame and the steel cage, and the surrounding rock of the pilot tunnel 26 serves as the load-bearing foundation of the support system.

[0040] In this method, the I20a type steel arch frame 19 of the initial support 1 of the first tunnel of the arch tunnel is connected to the large arch foot steel cage 17 through steel arch frame connecting steel bars 25 and M20×70 bolt group 22. The large arch foot steel arch frame triangular bracing structure 18 is composed of I20a type steel arch frame 19, connecting steel plate 20, stiffening steel plate 21 and M20×70 bolt group 22. The inner φ8 steel mesh 23 and the outer φ8 steel mesh 24 are respectively installed on the inner and outer sides of the I20a type steel arch frame 19. The large arch foot 4 of the initial support on the rock-clamped side of the first tunnel of the arch tunnel is constructed in two stages. First, the steel cage 17 is constructed and then shotcrete is used for sealing. Then, the steel arch frame triangular bracing 18 is constructed and shotcrete is used for sealing. The invert arch structure 5 of the initial support of the first tunnel of the arch tunnel and the invert arch structure 6 of the secondary lining of the first tunnel of the arch tunnel are set at the bottom of the first tunnel in sequence. The invert arch filling structure 7 fills the secondary lining of the first tunnel of the arch tunnel. Above the invert arch structure 6; the secondary lining arch structure 8 of the first tunnel of the connecting arch tunnel is set on the top of the first tunnel; the initial support structure 9 of the second tunnel of the connecting arch tunnel adopts I18 type steel arch frame, the anchor rod 10 of the second tunnel system adopts inclined grouting pipe, and the advanced grouting small pipe 11 of the second tunnel is used for advanced reinforcement; the interlocking rock tie anchor cable 12 of the connecting arch tunnel is connected to the first tunnel and the second tunnel through PVC protective sleeve 28. The interlocking rock tie anchor cable 12 of the connecting arch tunnel can offset part of the surrounding rock pressure and increase the stability of the interlocking rock; the invert arch structure 13, the secondary lining invert arch structure 14, the invert arch filling structure 15 and the secondary lining arch structure 16 of the second tunnel of the connecting arch tunnel are similar to the corresponding structures of the first tunnel, but the thickness and structure are different. The thickness of the secondary lining invert arch of the second tunnel is 45cm, and a conventional structure is adopted. The thickness of the secondary lining arch of the second tunnel gradually changes from 65cm on the side of the interlocking rock to 45cm away from the side of the interlocking rock.

[0041] The initial support of the pilot tunnel 1 adopts an I20a type steel arch frame 19, an inner φ8 steel mesh 23, an outer φ8 steel mesh 24, steel arch frame connecting steel bars 25, a large arch foot steel cage 17, a large arch foot steel arch frame triangular bracing structure 18, connecting steel plates 20 and stiffening steel plates 21, forming a high-strength and high-rigidity support system, effectively dispersing the surrounding rock pressure and reducing local damage;

[0042] The system anchor bolts 2 and radial grouting pipes 3 reinforce the surrounding rock through grouting, further enhancing the stability of the surrounding rock. The initial support arch foot 4 on the middle rock side provides additional support and enhances the overturning resistance of the wall foot. The initial support invert arch structure 5 of the pilot tunnel of the continuous arch tunnel and the secondary lining invert arch structure 6 of the pilot tunnel of the continuous arch tunnel adopt a gradual thickness design, which optimizes the structural stress, increases the cross-sectional area of ​​the wall foot, and improves the bending strength.

[0043] The initial support structure 9 and system anchors 10 of the subsequent tunnel provide reliable initial support for the subsequent tunnel, reducing the impact on the preceding tunnel. The advanced grouting pipes 11 are used for advanced grouting reinforcement of the subsequent tunnel, reducing the impact of construction on the preceding tunnel. In the interlocking arch tunnel, the interlocking rock tie-bar anchors 12 connect the preceding and subsequent tunnels through PVC protective sleeves 28, providing additional restraint and enhancing the stability of the interlocking rock. The synergistic effect of these structural components not only improves the overall stability of the tunnel but also optimizes the construction process, reduces engineering costs, and provides a reliable solution for tunnel construction under complex geological conditions.

[0044] The outer side of the large arch foot 4 of the initial support on the side of the interlocking rock in the pilot tunnel of the twin-arch tunnel is coated with a superhydrophobic nano-coating. The superhydrophobic nano-coating is applied by spraying and has a thickness of 5-8μm.

[0045] By applying a superhydrophobic nano-coating 7 to the outer side of the initial support arch foot 4 on the rock side in the pilot tunnel, water penetration can be effectively prevented, the durability and waterproof performance of the support structure can be improved, and structural damage caused by water erosion can be reduced.

[0046] The I20a type steel arch frame 19 of the initial support 1 of the pilot tunnel of the continuous arch tunnel is fixedly connected to the main arch foot steel reinforcement cage 17 by M20×70 bolt group 22 and steel arch frame connecting steel reinforcement 25. The connecting steel plate 20 and stiffening steel plate 21 of the main arch foot steel arch frame triangular brace structure 18 are connected to the I20a type steel arch frame 19 by M20×70 bolt group 22.

[0047] Through the connection between the I20a type steel arch frame 19 and the large arch foot steel reinforcement cage 17, and the setting of the large arch foot steel arch frame triangular bracing structure 18, the entire initial support structure of the pilot tunnel forms an organic whole, which can effectively cope with complex surrounding rock conditions and various adverse factors in the construction process.

[0048] This connection method not only improves the load-bearing capacity and stability of the support structure, but also reduces the need for temporary support during construction, thereby lowering construction costs and safety risks.

[0049] An expansion joint, 5 cm wide, is provided between the secondary lining invert arch structure 6 and the secondary lining arch ring structure 8 in the pilot tunnel of the twin-arch tunnel. The expansion joint is filled with elastic sealing material. This design can effectively adapt to the deformation of the tunnel structure, prevent structural cracking caused by temperature changes or ground stress, and improve the tunnel's waterproof performance and durability.

[0050] In the continuous arch tunnel, the two ends of the rock-clamped anchor cable 12 are respectively anchored in the initial support structure of the first tunnel and the second tunnel. The rock-clamped anchor cable 12 in the continuous arch tunnel is protected by the PVC protective sleeve 28 of the anchor cable through prestress. The prestress locking value of the rock-clamped anchor cable 12 in the continuous arch tunnel is determined according to the tunnel surrounding rock pressure.

[0051] By installing the rock-clamping anchor cable 12 in the arch tunnel, the structural connection between the first and second tunnels is enhanced, the surrounding rock pressure is effectively dispersed, and the impact of surrounding rock deformation on the support structure is reduced.

[0052] The use of PVC protective sleeve 28 further improves the durability and reliability of rock-clamped anchor cables 12 in the arch tunnel, ensuring their effectiveness in long-term use.

[0053] A reasonable design of prestress locking values ​​can optimize the stress state of the support system, improve the stability and safety of the entire support system, and provide reliable support for the construction of asymmetric arch tunnels without a central wall.

[0054] Both the radial grouting guide pipe 3 in the initial tunnel and the advanced grouting guide pipe 11 in the subsequent tunnel use Φ4.2cm grouting guide pipes. The radial grouting guide pipe 3 is 600cm long, and the advanced grouting guide pipe 11 is 300cm long. The radial grouting guide pipe 3 is installed on the side of the interbedded rock in the initial tunnel to reinforce the surrounding rock, and the advanced grouting guide pipe 11 is used for advanced grouting reinforcement in the subsequent tunnel.

[0055] By injecting cement grout (water-cement ratio of 0.5-0.6) into the surrounding rock fissures and weak structural surfaces, the unconformity surfaces and fissures of the surrounding rock are effectively filled and cemented. The synergistic effect of the radial grouting pipe 3 and the advanced grouting pipe 11 ensures that the surrounding rock of both the first and second tunnels is effectively reinforced during construction, reducing the impact of surrounding rock deformation on the support structure. Through grouting reinforcement, the integrity and stability of the surrounding rock are improved, providing more reliable surrounding rock conditions for the support system of the asymmetric arch tunnel without a central wall, and ensuring the safety and stability of the entire tunnel construction and operation process.

[0056] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the scope of protection of this utility model.

Claims

1. An asymmetric arch tunnel support system without a central wall, comprising initial support for the pilot tunnel of the arch tunnel (1), characterized in that, The initial support (1) of the pilot tunnel of the continuous arch tunnel includes an I20a type steel arch frame (19), an inner φ8 steel mesh (23), an outer φ8 steel mesh (24), steel arch frame connecting steel bars (25), a large arch foot steel cage (17), a large arch foot steel arch frame triangular bracing structure (18), a large arch foot steel arch frame connecting steel plate (20), and a stiffening steel plate (21). The anchor bolt (2) of the pilot tunnel system of the arch tunnel adopts a 600cm long Φ4.2cm radial grouting pipe and is installed on the rock side in the pilot tunnel; The initial support arch foot (4) of the interlocking rock side in the pilot tunnel of the continuous arch tunnel is composed of a large arch foot steel cage (17), a large arch foot steel arch frame triangular bracing structure (18), a connecting steel plate (20) and a stiffening steel plate (21). The bottom of the pilot tunnel is provided with an initial support arch structure (5) for the pilot tunnel of the arch tunnel. Above the arch structure (5) is a secondary lining arch structure (6) for the pilot tunnel of the arch tunnel. Above the secondary lining arch structure (6) for the pilot tunnel of the arch tunnel is a filling structure (7) for the pilot tunnel of the arch tunnel. The secondary lining arch structure (8) of the first tunnel of the continuous arch tunnel gradually changes from 70cm thick on the side of the middle rock to 45cm thick on the side away from the middle rock. The initial support structure (9) of the second tunnel of the continuous arch tunnel adopts I18 type steel arch frame. The anchor rod (10) of the second tunnel system of the continuous arch tunnel adopts 300cm long Φ4.2cm inclined 45° grouting pipe. The small guide pipe (11) for grouting ahead of the rear tunnel of the arch tunnel is used for grouting ahead of the rear tunnel. The tie anchor cable (12) of the interlocking rock in the arch tunnel is connected to the first tunnel and the rear tunnel through the PVC protective sleeve (28). The secondary lining arch structure (16) of the rear tunnel of the arch tunnel gradually changes from 65cm thick on the side of the interlocking rock to 45cm thick away from the side of the interlocking rock.

2. The asymmetric arch tunnel support system without a central wall as described in claim 1, characterized in that: The outer side of the initial support arch foot (4) on the rock side of the pilot tunnel of the continuous arch tunnel is coated with a superhydrophobic nano-coating. The superhydrophobic nano-coating is applied by spraying and has a thickness of 5-8μm.

3. The asymmetric arch tunnel support system without a central wall as described in claim 2, characterized in that: The I20a type steel arch frame (19) of the initial support (1) of the pilot tunnel of the continuous arch tunnel is fixedly connected to the large arch foot steel reinforcement cage (17) by M20×70 bolt group (22) and steel arch frame connecting steel reinforcement (25). The connecting steel plate (20) and stiffening steel plate (21) of the large arch foot steel arch frame triangular brace structure (18) are connected to the I20a type steel arch frame (19) by M20×70 bolt group (22).

4. The asymmetric arch tunnel support system without a central wall as described in claim 3, characterized in that: An expansion joint is reserved between the secondary lining inverted arch structure (6) and the secondary lining arch ring structure (8) of the first tunnel of the continuous arch tunnel, and the width of the expansion joint is 5cm.

5. The asymmetric arch tunnel support system without a central wall according to claim 4, characterized in that: The two ends of the rock-clamped anchor cable (12) in the arch tunnel are respectively anchored in the initial support structure of the first tunnel and the second tunnel. The rock-clamped anchor cable (12) in the arch tunnel is protected by the PVC protective sleeve (28) of the anchor cable through prestress. The prestress locking value of the rock-clamped anchor cable (12) in the arch tunnel is determined according to the tunnel surrounding rock pressure.

6. The asymmetric arch tunnel support system without a central wall according to claim 5, characterized in that: The radial grouting guide pipe (3) in the first tunnel of the continuous arch tunnel and the advanced grouting guide pipe (11) in the second tunnel both adopt Φ4.2cm grouting guide pipes. The radial grouting guide pipe (3) is 600cm long and the advanced grouting guide pipe (11) is 300cm long. The radial grouting guide pipe (3) is installed on the side of the interbedded rock in the first tunnel to reinforce the surrounding rock. The advanced grouting guide pipe (11) is used for advanced grouting reinforcement in the second tunnel.

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