Tunnel high-section primary support structure and construction method

Abstract

The application belongs to the field of tunnel construction, and particularly discloses a tunnel high-section primary support structure and a construction method, wherein the construction method comprises the following steps: after spraying a first layer of concrete to seal a rock surface, installing a primary support assembly; spraying a second layer of concrete and installing a connecting piece for penetrating and connecting the first layer of concrete and the second layer of concrete; spraying a third layer of concrete, and the connecting surface of the second layer of concrete and the third layer of concrete is located at a height different from the center height of the primary support assembly. The tunnel high-section primary support structure comprises a support steel frame embedded in the concrete, and the primary support assembly is provided with multiple layers in the direction from the outside to the inside of the tunnel; the connecting assembly comprises a first connecting piece for connecting the multiple layers of support steel frames and a second connecting piece for connecting the multiple layers of concrete. The scheme of the application can solve the problems of high-section support concrete, i.e., the difficulty in spraying due to the large spraying thickness and large self-weight, and the problem of the anchor rod end scraping the waterproof plate.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction, specifically relating to the high-section initial support structure of tunnels and its construction method. Background Technology

[0002] With the rapid development of the transportation industry, the construction of single-bore four-lane or larger extra-large span tunnels is becoming increasingly common. For large-span or extra-large span tunnels, the method of excavating pilot tunnels with sidewalls is generally adopted. During tunnel construction, shotcrete needs to be sprayed inside the tunnel. Especially for extra-large span tunnels, high-section shotcrete (meaning the total thickness of the shotcrete reaches more than 30cm) is required to meet the support requirements. However, if such a large thickness of concrete is sprayed directly, the strong initial support stiffness is not conducive to the release of the surrounding rock load during the excavation of the pilot tunnel, affecting the self-supporting capacity of the surrounding rock, and is also not conducive to the coordinated stress between the tunnel surrounding rock and the initial concrete. At the same time, the high-section concrete has a large shotcrete thickness and heavy weight, which makes the spraying more difficult and is prone to increased concrete rebound rate, leading to spalling, increasing project costs, and is also not conducive to safe tunnel construction.

[0003] In addition, according to the "Technical Specifications for Highway Tunnel Construction," during tunnel construction, in sections with supporting steel frames, anchor bolts need to be installed after shotcrete application, such as... Figure 1 As shown, anchor rod 3 is embedded in concrete 2 to increase the strength of concrete 2. However, in order to install anchor rod 3, the end of anchor rod 3 will protrude 5-10cm outside concrete 2, that is, the end of anchor rod 3 extends into the inside of tunnel 1. When the waterproof membrane is then installed on the inner wall of concrete 2, interference may occur when the waterproof membrane is installed to the exposed anchor rod 3, or even the anchor rod 3 may puncture the waterproof membrane, affecting the waterproof effect of tunnel 1. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-section initial support structure and construction method for tunnels, thereby solving the problem that the spraying of high-section support concrete is difficult due to its large spraying thickness and heavy weight.

[0005] According to embodiments of the present invention, the present invention adopts the following technical solution:

[0006] The construction method for high-section tunnels includes the following steps:

[0007] Steps: After spraying the first layer of concrete to seal the rock surface, install the initial support components;

[0008] Steps: Spray the second layer of concrete and install the connectors that connect the first and second layers of concrete, with the ends of the connectors extending out of the second layer of concrete;

[0009] Steps: Spray the third layer of concrete, embedding the end of the connector within it. The end of the initial support component extends to the third layer of concrete, which also embeds the initial support component within it. The connection surfaces of the second and third layers of concrete are offset from the center height of the initial support component.

[0010] After the three layers of concrete are sprayed, the first layer of support construction is completed.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. In this scheme, the shotcrete is sprayed in three stages. Under the premise that the total thickness of the shotcrete is fixed, the thickness of the shotcrete in each stage is reduced, and the self-weight of the shotcrete in each stage is also reduced. This reduces the difficulty of spraying, reduces the occurrence of block falling due to increased concrete rebound rate, reduces costs, and makes construction safer.

[0013] Furthermore, after the first and second layers of concrete are sprayed, the initial support stiffness of the concrete is not high enough, which is equivalent to only completing part of the total support stiffness. At this time, the surrounding rock has not yet received sufficient concrete support strength, so the surrounding rock can deform under stress. After the surrounding rock deforms, it can generate a reaction force on the pressure around the tunnel. Then, through the support force of the existing two layers of concrete, the bearing capacity of the surrounding rock is combined with the support force of the surrounding rock bearing capacity to form a synergistic force of "surrounding rock bearing capacity + partial concrete support", making full use of the bearing capacity of the surrounding rock.

[0014] Compared to existing technologies that directly spray a large thickness of concrete to meet the overall support stiffness requirements, which in turn leads to an inability to utilize the bearing capacity of the surrounding rock due to excessive concrete rigidity, this solution, while fully utilizing the bearing capacity of the surrounding rock, allows for a reduction in the total thickness of the three-layer concrete sprayed to some extent compared to the thickness of directly sprayed concrete to meet the overall support stiffness requirements. The support stiffness resulting from this reduction in concrete thickness can be compensated for by the bearing capacity of the surrounding rock.

[0015] 2. The shotcrete is applied in multiple layers. Multi-layer shotcrete may result in delamination, meaning insufficient bonding strength between the layers. To address this, this design incorporates a primary support component and connectors embedded throughout the multiple layers of concrete, enhancing the rigid connection strength between them. Correspondingly, the total height of the primary support component is approximately equal to the total thickness of the shotcrete. Since the shear force is greatest at the height of the structural centerline (the center height of the primary support component), the connection between the second and third layers is staggered from the center height of the primary support component. This prevents the connection point from coinciding with the location of maximum shear force, thus improving the shear strength of the multi-layer concrete structure to some extent.

[0016] In addition, the connectors are installed after the second layer of concrete to meet the existing construction specifications. The exposed ends of the connectors are also embedded in the third layer of concrete. Thus, the connectors can meet the construction specifications and also serve to connect the second and third layers of concrete. They are not exposed and will not affect the subsequent installation of the waterproof membrane on the inner wall of the third layer of concrete.

[0017] According to embodiments of the present invention, the present invention also employs the following technical solutions:

[0018] A method for constructing high-section tunnels, characterized by comprising the following steps:

[0019] Steps: After spraying the first layer of concrete to seal the rock surface, install the initial support components;

[0020] Steps: Spray the second layer of concrete and install the connectors that connect the first and second layers of concrete, with the ends of the connectors extending out of the second layer of concrete;

[0021] Steps: Spray the third layer of concrete, with the end of the connector extending out of the third layer of concrete, and the end of the primary support component extending to the third layer of concrete. The third layer of concrete will also embed the primary support component or expose the end of the primary support component. The connection surfaces of the second and third layers of concrete are staggered from the center height of the primary support component.

[0022] After the three layers of concrete are sprayed, one layer of support construction is completed. Multiple layers of support construction are carried out in sequence from the outside to the inside of the tunnel. The third layer of concrete in the innermost support construction embeds the end of the connector inside.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] When a single layer of support construction is insufficient to meet the support requirements, multi-layer support construction can be carried out. The concrete of multi-layer support construction is connected by connectors, which to a certain extent meets the connection strength requirements between multi-layer support construction.

[0025] According to embodiments of the present invention, the present invention also employs the following technical solutions:

[0026] The high-section initial support structure of the tunnel includes an initial support assembly and a connecting assembly. The initial support assembly includes a support steel frame embedded in the concrete. The initial support assembly has multiple layers along the direction from the outside to the inside of the tunnel. Each layer of the initial support assembly has multiple support steel frames along the length of the tunnel. The connecting assembly includes a first connector for connecting the multiple layers of support steel frames and a second connector for connecting the multiple layers of concrete.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] When multi-layer support construction is carried out to meet the concrete construction thickness, it is necessary to construct multi-layer primary support components. The multi-layer primary support components are connected by the first connector to improve the connection strength of adjacent primary support components, so that the multi-layer primary support components are subjected to overall force. At the same time, it can also improve the connection strength of multi-layer support construction and increase the connection strength between the concrete in multi-layer support construction. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure for anchor bolt construction in the background art of this invention.

[0030] Figure 2 This is a schematic diagram of the overall structure of Embodiment 2 of the present invention.

[0031] Figure 3 This is a schematic diagram of the overall structure of Embodiments 1 and 3 of the present invention.

[0032] Figure 4 This is a front view of the tunnel according to an embodiment of the present invention.

[0033] In the diagram: 1. Tunnel; 2. Concrete; 3. Anchor bolt; 4. First layer of concrete; 5. Steel mesh; 6. Support frame; 7. Second layer of concrete; 8. Third layer of concrete; 9. Pad; 10. Nut; 11. Connecting steel bars; 12. Temporary support frame. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings, and specific embodiments are given.

[0035] Example 1

[0036] like Figure 3 As shown, the high-section initial support structure of the tunnel includes an initial support assembly and a connecting assembly. The initial support assembly includes a support steel frame 6 embedded in the concrete. The initial support assembly has multiple layers along the tunnel 1 from the outside to the inside, that is, multiple layers of support steel frames 6 are set along the tunnel 1 from the outside to the inside. Each layer of the initial support assembly has multiple support steel frames 6 along the length of the tunnel 1 to provide support for the tunnel 1 along the length of the tunnel 1. Through the multiple support steel frames 6 set along the length of the tunnel 1 and the multiple layers of support steel frames 6 set along the tunnel 1 from the outside to the inside, the length requirements for the construction of the tunnel 1 are met, and the concrete section height requirements for the construction of the tunnel 1 are also met.

[0037] The connecting assembly includes a first connector for connecting the multi-layer support steel frame 6, a second connector for connecting the multi-layer concrete, and a third connector for sequentially connecting the multiple support steel frames 6 along the length of the tunnel 1.

[0038] Specifically, the first connector includes connecting steel bars 11. Multiple connecting steel bars 11 are provided and staggered along both sides of the support steel frame 6. Specifically, connecting steel bars 11 are welded to both sides of the support steel frame 6, and the projections of the connecting steel bars 11 on both sides of the support steel frame 6 along the length of the tunnel 1 do not overlap. The connecting steel bars 11 connect the multiple layers of support steel frames 6, improving the connection strength between the multiple layers of support steel frames 6. The support steel frames 6 of adjacent initial support components are sequentially fixed and connected. Specifically, the opposite end faces of the support steel frames 6 of adjacent initial support components can be directly welded together, or they can be connected and fixed using existing technologies, such as bolt connections. The two layers of support steel frames 6 are first connected and then welded, further improving the connection strength between the multiple layers of support steel frames 6.

[0039] The second connector includes an anchor rod 3 that penetrates multiple layers of concrete. The end of the anchor rod 3 facing the inside of the tunnel 1 is embedded in the concrete, and the anchor rod 3 is fixedly connected to the support steel frame 6 of the multi-layer initial support assembly. On the one hand, the anchor rod 3 connects multiple layers of concrete, enhancing the connection strength between the multiple layers of separately sprayed concrete, and to a certain extent solving the problem of insufficient strength caused by the layering of multiple layers of concrete. On the other hand, the anchor rod 3 is connected to the multi-layer support steel frame 6, further enhancing the connection strength between the multiple layers of support steel frame 6, thereby enhancing the support strength and connection strength of the support steel frame 6 to the multiple layers of concrete.

[0040] The third connector includes multiple layers of reinforcing mesh 5 arranged vertically along the support steel frame 6. At least one layer of reinforcing mesh 5 is positioned at the center height of the support steel frame 6. In this embodiment, three layers of reinforcing mesh 5 are used as an example (see reference). Figure 2 As shown in the diagram, three layers of reinforcing mesh 5 are respectively installed at the top, middle, and bottom of the support steel frame 6, serving to connect multiple support steel frames 6 together, allowing the multiple support steel frames 6 to bear the force as a whole, thus enhancing the support strength of the initial support assembly in the length direction of the tunnel 1. In addition, after the sprayed concrete solidifies, it will solidify within the mesh of the reinforcing mesh 5, thereby forming a state where the concrete passes through both sides of the reinforcing mesh 5 and fixes the reinforcing mesh 5 within it, increasing the connection strength between the reinforcing mesh 5 and the concrete.

[0041] Example 2

[0042] like Figure 2 As shown, the high-section tunnel construction method includes the following steps:

[0043] Step A: Construction preparation, using the sidewall pilot tunnel method to complete the excavation of the pilot tunnel.

[0044] Step B: Shotcrete the first layer of concrete 4 to seal the rock surface. The thickness of the first layer of concrete 4 is 3-5cm. The first layer of concrete 4 is used to prevent the surrounding rock from loosening and collapsing. Then, install the initial support components. Specifically, the initial support components are the initial support components in the high cross-section tunnel initial support structure described in Example 1. First, fix the steel mesh 5 located at the top of the support frame 6 to the inner wall of the first layer of concrete 4. Then, fix several support frames 6 along its length. The height of the support frame 6 is equal to the sum of the thicknesses of the second layer of concrete 7 and the third layer of concrete 8. Then, fix a layer of steel mesh 5 in the middle and bottom of the support frame 6 respectively.

[0045] Step C: Spray the second layer of concrete 7. The second layer of concrete 7 will partially bury the support steel frame 6 and embed the steel mesh 5 in the middle of the support steel frame 6. That is, after the second layer of concrete 7 is sprayed, the steel mesh 5 at the top and middle of the support steel frame 6 will be buried in the second layer of concrete 7.

[0046] Install a connector for penetrating and connecting the first layer of concrete 4 and the second layer of concrete 7. The connector referred to here is the second connector in the connecting assembly of the high cross-section initial support structure of the tunnel described in Example 1, namely the anchor rod 3. Insert the end of the anchor rod 3 into the second layer of concrete 7 and penetrate through the first layer of concrete 4. The end of the anchor rod 3 facing out of the tunnel 1 can extend into the surrounding rock outside the first layer of concrete 4. At this time, the end of the anchor rod 3 facing in the tunnel 1 is exposed in the second layer of concrete 7. Then, a pad 9 is fitted on the part of the anchor rod 3 exposed outside the second layer of concrete 7, and the pad 9 is fixed by a nut 10 so that the pad 9 abuts against the inner wall of the second layer of concrete 7.

[0047] Combination Figure 4 As shown, after spraying the second layer of concrete 7, a temporary support steel frame 12 is installed inside the tunnel 1 to assist in supporting the rock surface. Specifically, a steel frame from the prior art is selected as the temporary support steel frame 12. The lower end of the temporary support steel frame 12 is connected to the bottom of the tunnel 1, and the upper end of the temporary support steel frame 12 is connected to the top of the tunnel 1. Specifically, the lower end of the temporary support steel frame 12 is bolted to the support steel frame 6 located at the bottom of the tunnel 1, and the upper end of the temporary support steel frame 12 is bolted to the support steel frame 6 located at the top of the tunnel 1. The temporary support steel frame 12 assists the initial support components, thereby improving the support strength of the tunnel 1. Since only the first layer of concrete 4 and the second layer of concrete 7 have been sprayed at this time, the total thickness of the concrete is not yet up to standard, meaning that the initial support stiffness of the concrete is not high enough. It is equivalent to only completing part of the total support stiffness. At this time, the temporary support steel frame 12 can be set up to form a synergistic force of "surrounding rock bearing capacity + partial concrete support + temporary support steel frame 12", which not only meets the support strength for the pilot tunnel of Tunnel 1, but also makes full use of the surrounding rock bearing capacity according to the New Austrian Tunneling Method.

[0048] Step D: Spray the third layer of concrete 8. The third layer of concrete 8 embeds the end of the connector within it, meaning the end of the anchor rod 3 is completely embedded within it, preventing the end of the anchor rod 3 from being exposed. The end of the initial support component extends to the third layer of concrete 8, meaning the lower end of the support frame 6 is still exposed outside the second layer of concrete 7 at this point. Spraying the third layer of concrete 8 also embeds the lower end of the support frame 6 within it. The connection surface between the second layer of concrete 7 and the third layer of concrete 8 is offset from the center height of the initial support component. Since the steel mesh 5 located in the middle of the support frame 6 has been embedded within the second layer of concrete 7 during spraying, the connection surface between the third layer of concrete 8 and the second layer of concrete 7 is offset from the middle of the support frame 6, thus preventing the connection point of the two layers of concrete from coinciding with the location of maximum shear force, and to a certain extent improving the shear strength of the multi-layer concrete.

[0049] In step BD above, three layers of concrete are sprayed sequentially from the outside to the inside of tunnel 1. Completion of the three layers of concrete spraying constitutes the completion of one layer of support construction. Then, the excavation of subsequent pilot tunnels continues. For each pilot tunnel excavated, support is provided through step BD. Once the excavation and support of the entire tunnel are completed, the concrete at the temporary support steel frame 12 is removed, the bolts connecting the temporary support steel frame 12 to the support steel frame 6 of tunnel 1 are loosened, and the temporary support steel frame 12 is dismantled. In actual construction, when spraying the third layer of concrete 8, the upper and lower ends of the temporary support steel frame 12 can be avoided to facilitate subsequent dismantling of the temporary support steel frame 12.

[0050] Example 3

[0051] Based on Example 2, if the total cross-sectional thickness of the concrete still cannot meet the requirements after completing one layer of support construction, such as... Figure 3 As shown, multi-layer support construction is carried out sequentially from the outside to the inside of tunnel 1, and the initial support components of adjacent layers are connected sequentially. Specifically, the connecting steel bars 11 in the connecting components of the initial support structure of the large-span tunnel 1 in Example 1 are used to connect the support steel frames 6 of the adjacent initial support components, and the support steel frames 6 of the adjacent layers are welded and fixed. The specific construction steps are as follows (taking two-layer support construction as an example):

[0052] Step a: Construction preparation, using the sidewall pilot tunnel method to complete the excavation of the pilot tunnel.

[0053] Step b: Construction of the first layer of support:

[0054] b1: The first layer of sprayed concrete 4 seals the rock surface. The thickness of the first layer of sprayed concrete 4 is 3-5cm. The first layer of concrete 4 is used to prevent the surrounding rock from loosening and collapsing. Then, the initial support components are installed. Specifically, the initial support components are the initial support components in the high cross-section tunnel initial support structure described in Example 1. First, the steel mesh 5 located at the top of the support steel frame 6 is fixed to the inner wall of the first layer of concrete 4. Then, several support steel frames 6 are fixed along its length. The height of the support steel frame 6 is equal to the sum of the thicknesses of the second layer of concrete 7 and the third layer of concrete 8. Then, a layer of steel mesh 5 is fixed in the middle and bottom of the support steel frame 6 respectively. Connecting steel bars 11 are fixed at both ends of the support steel frame 6.

[0055] b2: Spray the second layer of concrete 7. The second layer of concrete 7 will partially bury the support steel frame 6 and embed the steel mesh 5 in the middle of the support steel frame 6. That is, after the second layer of concrete 7 is sprayed, the steel mesh 5 at the top and middle of the support steel frame 6 will be buried in the second layer of concrete 7.

[0056] Install a connector for penetrating and connecting the first layer of concrete 4 and the second layer of concrete 7. The connector referred to here is the second connector in the connecting assembly of the high cross-section initial support structure of the tunnel described in Example 1, namely the anchor rod 3. Insert the end of the anchor rod 3 into the second layer of concrete 7 and penetrate through the first layer of concrete 4. The end of the anchor rod 3 facing out of the tunnel 1 can extend into the surrounding rock outside the first layer of concrete 4. At this time, the end of the anchor rod 3 facing inward of the tunnel 1 is exposed in the second layer of concrete 7.

[0057] b3: Spray the third layer of concrete 8. When spraying the third layer of concrete 8, the lower ends of the anchor rod 3, the support steel frame 6, and the connecting steel bar 11 are still exposed outside the third layer of concrete 8.

[0058] Step c: Construction of the second layer of support:

[0059] c1: The exposed lower end of the support steel frame 6 in the first layer of support construction is the location where the first layer of concrete 4 is sprayed in the second layer of support construction.

[0060] c2: Weld the second layer of support steel frame 6 to the lower end of the exposed first layer of support steel frame 6, and fix the second layer of support steel frame 6 and the connecting steel bar 11. The steel mesh 5 at the lower end of the support steel frame 6 in the first layer of support construction is also regarded as the steel mesh 5 at the upper end of the support steel frame 6 in the second layer of support construction. That is, the lower end of the first layer of support steel frame 6 and the upper end of the second layer of support steel frame 6 are both fixed on the same steel mesh 5.

[0061] The second layer of concrete 7 is sprayed into the second layer of support construction, embedding the steel mesh 5 in the middle of the support steel frame 6. At this time, the end of the anchor rod 3 is still exposed. Then, the part of the anchor rod 3 exposed outside the second layer of concrete 7 is fitted with a pad 9, and the pad 9 is fixed with a nut 10, so that the pad 9 abuts against the inner wall of the second layer of concrete 7.

[0062] c3: The third layer of concrete 8 is sprayed, which completely embeds the end of the anchor rod 3, so that the end of the anchor rod 3 is not exposed. The end of the initial support component extends to the third layer of concrete 8, that is, the lower end of the support steel frame 6 and the connecting steel bar 11 is still exposed outside the second layer of concrete 7 at this time. When the third layer of concrete 8 is sprayed, the lower end of the support steel frame 6 and the connecting steel bar 11 is also embedded inside.

[0063] In actual operation, in order to meet the requirements of the high cross-section of Tunnel 1, multi-layer support construction can be carried out according to the above steps.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for constructing high-section tunnels, characterized in that, Includes the following steps: Steps: After spraying the first layer of concrete to seal the rock surface, install the initial support components, which include a support steel frame. Multiple layers of steel mesh are vertically installed along the support steel frame. The steel mesh at the top of the support steel frame is fixed to the inner wall of the first layer of concrete. Several support steel frames are fixed along its length. The steel mesh is used to connect multiple support steel frames along the tunnel length in sequence. The height of the support steel frame is equal to the sum of the thicknesses of the second and third layers of concrete. A layer of steel mesh is fixed at the middle and bottom of the support steel frame, respectively. Step: Spray a second layer of concrete, embedding the steel mesh in the middle of the support frame; A connector is installed to connect the first and second layers of concrete, with the end of the connector extending out of the second layer of concrete; a temporary support steel frame is installed inside the tunnel to assist in supporting the rock face. Steps: Spray the third layer of concrete, embedding the end of the connector within it. The end of the initial support component extends to the third layer of concrete, which also embeds the initial support component within it. The connection surfaces of the second and third layers of concrete are offset from the center height of the initial support component. After the three layers of concrete are sprayed, the first layer of support construction is completed, and the temporary support steel frame is removed.

2. The tunnel high-section construction method according to claim 1, characterized in that: Three layers of concrete were sprayed sequentially along the tunnel from the outside to the inside.

3. A method for constructing high-section tunnels, characterized in that, Includes the following steps: Steps: After spraying the first layer of concrete to seal the rock surface, install the initial support components, which include a support steel frame. Multiple layers of steel mesh are vertically installed along the support steel frame. The steel mesh at the top of the support steel frame is fixed to the inner wall of the first layer of concrete. Several support steel frames are fixed along its length. The steel mesh is used to connect multiple support steel frames along the tunnel length in sequence. The height of the support steel frame is equal to the sum of the thicknesses of the second and third layers of concrete. A layer of steel mesh is fixed at the middle and bottom of the support steel frame, respectively. Steps: Spray a second layer of concrete, embedding the steel mesh in the middle of the support frame; And install connectors for penetrating and connecting the first layer of concrete and the second layer of concrete, with the ends of the connectors extending out of the second layer of concrete; Steps: Spray the third layer of concrete, with the end of the connector extending out of the third layer of concrete, and the end of the primary support component extending to the third layer of concrete. The third layer of concrete will also embed the primary support component or expose the end of the primary support component. The connection surfaces of the second and third layers of concrete are staggered from the center height of the primary support component. After the three layers of concrete are sprayed, one layer of support construction is completed. Multiple layers of support construction are carried out in sequence from the outside to the inside of the tunnel. The third layer of concrete in the innermost support construction embeds the end of the connector inside.

4. The tunnel high-section construction method according to claim 3, characterized in that: The initial support components of adjacent layers are connected sequentially.

5. A high-section initial support structure for tunnels, characterized in that: The system includes initial support components and connecting components. The initial support components include support steel frames embedded in concrete. The initial support components are arranged in multiple layers along the tunnel from the outside to the inside, and the initial support components are embedded through multiple layers of concrete. The total height of the multiple initial support components is equal to the total thickness of the sprayed concrete. Each layer of the initial support components has multiple support steel frames along the tunnel length. The connecting components include a first connector for connecting the multiple layers of support steel frames and a second connector for connecting the multiple layers of concrete. The connecting components also include a third connector for sequentially connecting multiple support steel frames along the tunnel length. The third connector includes multiple layers of steel mesh arranged vertically along the support steel frames. At least one layer of steel mesh is set at the center height of the support steel frame. The connection surfaces of the second and third layers of concrete in each layer of support construction are staggered from the center height of the initial support components.

6. The tunnel high-section initial support structure according to claim 5, characterized in that: The first connector includes connecting steel bars, which are provided in multiples and staggered along both sides of the support steel frame; and the support steel frames of adjacent initial support components are fixedly connected in sequence.

7. The tunnel high-section initial support structure according to claim 5, characterized in that: The second connector includes an anchor rod that penetrates multiple layers of concrete, with the end of the anchor rod facing the inside of the tunnel embedded in the concrete, and the anchor rod is fixedly connected to the support steel frame of the multiple-layer initial support assembly.

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