Tunnel embedded arch bridge type spanning structure and construction method thereof

Abstract

The invention discloses a tunnel embedded arch bridge type crossing structure and a construction method thereof, one side of a karst cave is communicated with a roundabout pilot tunnel, and the roundabout pilot tunnel is used as a cleaning and carrying channel for deposits in the karst cave; the crossing structure comprises a tunnel structure, a bridge structure and a reinforcing structure. The karst cave is sequentially provided with the reinforcing structure, the tunnel structure and the bridge structure from top to bottom. Differential settlement can be avoided, construction is easy, structural stress is coordinated, a force transmission route is clear, the structural stability and safety when the tunnel passes through the deep and narrow karst cave can be guaranteed, and meanwhile the threat of dangerous rocks and falling rocks is avoided; the construction method provides reference for similar engineering construction.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to an embedded arch bridge-type spanning structure within a tunnel and its construction method. Background Technology

[0002] In recent years, with the rapid expansion of road networks, the construction of numerous tunnels in karst areas is inevitable. Due to limitations in exploration methods, tunnels may encounter giant karst caves and face the threat of falling rocks. When tunnels pass through deep and narrow karst caves, the conventional approach is to first backfill with ballast or use pile foundations with beams, and then construct the tunnel structure. A backfilling construction method for tunnels passing through giant karst caves at high elevations, patent number CN109630137A, presents several drawbacks. Ballast backfilling technology suffers from unpredictable accumulation and uneven settlement after construction; pile foundations with beams require pile foundations, which present difficulties in tunnel construction and issues with the load-bearing capacity of the piles and beams being mismatched.

[0003] There is an urgent need for a new structure to span giant karst caves and achieve better results, but there are currently no relevant examples of spanning structures available for reference in this field. Those skilled in the art urgently need a new method for constructing spanning structures. Summary of the Invention

[0004] The purpose of this invention is to provide a tunnel-embedded arch bridge-type crossing structure and its construction method, which solves the problems of structural stability and safety when tunnels pass through "deep and narrow" karst caves.

[0005] The present invention is implemented as follows: an arch bridge-type spanning structure embedded in a tunnel, with a detour guide tunnel connected to one side of the karst cave. The detour guide tunnel is connected to one side of the karst cave and serves as a channel for cleaning and transporting accumulated materials inside the karst cave. The spanning structure includes a tunnel structure, a bridge structure, and a reinforcement structure. The karst cave is provided with a reinforcement structure, a tunnel structure, and a bridge structure in sequence from top to bottom.

[0006] A further technical solution of the present invention is: the reinforcement structure includes a buffer layer, a backfill layer, and a protective arch arranged sequentially from top to bottom, and the protective arch is connected to the top of the tunnel structure.

[0007] A further technical solution of the present invention is: a large pipe shed is provided in the backfill layer, and the large pipe shed is inclined along the extension direction of the tunnel structure.

[0008] A further technical solution of the present invention is that the backfill material is C20 concrete.

[0009] A further technical solution of the present invention is: the tunnel structure includes initial support and secondary lining, wherein the initial support is placed on the outer periphery of the secondary lining and connected to the reinforcement structure.

[0010] A further technical solution of the present invention is: the bridge structure includes an arch bridge structure, an arch foundation, anchor bolts, and a filling layer. The arch foundation is placed at both ends of the arch bridge structure, and the filling layer is filled between the arch bridge structure and the tunnel structure. The anchor bolts are placed on both sides of the filling layer for reinforcement.

[0011] A further technical solution of the present invention is that the filling layer is made of C30 concrete.

[0012] A further technical solution of the present invention is that the detour guide tunnel is connected to the karst cave through a detour guide tunnel connecting channel.

[0013] The beneficial effects of this invention are: to develop a tunnel-embedded arch bridge-type crossing structure and its construction method, which avoids uneven settlement, is easy to construct, has coordinated structural stress and clear force transmission path, and can ensure the structural stability and safety of the tunnel when passing through "deep and narrow" karst caves, while avoiding the threat of falling rocks.

[0014] A construction method for an arch bridge-type spanning structure embedded in a tunnel is proposed, providing reference for similar engineering projects. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of a tunnel-embedded arch bridge-type spanning structure provided by the present invention;

[0016] Figure 2 This is a longitudinal section view of a tunnel-embedded arch bridge-type spanning structure provided by the present invention;

[0017] Figure 3 This is a plan view showing the positional relationship between the karst cave and the tunnel provided by the present invention;

[0018] Figure 4 This is a side view of the positional relationship between the karst cave and the tunnel provided by the present invention.

[0019] Attached reference numerals: 1. Initial support, 2. Secondary lining, 3. Arch support, 4. Arch bridge structure, 5. Arch foundation, 6. Anchor bolt, 7. Filling layer, 8. Pipe shed, 9. Backfill layer, 10. Buffer layer, 11. Detour tunnel, 12. Detour tunnel connecting passage, 13. Karst cave, 14. Tunnel face, 15. Detour tunnel face, 16. Weak accumulation body. Detailed Implementation

[0020] 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 also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0021] Example 1:

[0022] like Figure 1-4 The diagram shows an arch bridge-type spanning structure embedded in a tunnel. One side of the karst cave 13 is connected to a detour guide tunnel 11, which serves as a channel for cleaning and transporting accumulated materials within the karst cave 13. The spanning structure includes a tunnel structure, a bridge structure, and a reinforcement structure. The karst cave 13 is provided with the reinforcement structure, tunnel structure, and bridge structure in sequence from top to bottom.

[0023] This structure utilizes a dedicated detour tunnel to clear and transport debris within the karst cave, creating a safe and stable working space for the subsequent construction of the crossing structure. The crossing structure comprises, from top to bottom, the aforementioned reinforcement structure, tunnel structure, and bridge structure within the karst cave. It not only ensures the safety and controllability of the construction process but also guarantees the long-term stability and durability of the entire crossing structure during operation. This represents an innovative and effective technical approach to solving the global challenge of tunneling through giant karst caves.

[0024] This invention avoids uneven settlement, is easy to construct, has a coordinated structural stress distribution and a clear force transmission path, and can ensure the structural stability and safety of tunnels passing through "deep and narrow" karst caves, while avoiding the threat of falling rocks; it provides a reference for similar engineering construction.

[0025] In this embodiment, the reinforcement structure includes a buffer layer 10, a backfill layer 9, and a protective arch 3 arranged sequentially from top to bottom, and the protective arch 3 is connected to the top of the tunnel structure.

[0026] The multi-layered composite reinforcement structure is scientifically designed. The buffer layer and backfill layer can effectively absorb and disperse the impact energy of falling rocks from above, while the arch support serves as an enhanced support structure. Together, they form a multi-layered protection system, which greatly improves the load-bearing capacity and risk resistance of the tunnel structure.

[0027] In this embodiment, a large pipe shed 8 is provided in the backfill layer 9, and the large pipe shed 8 is inclined along the extension direction of the tunnel structure.

[0028] Setting up inclined large pipe sheds within the backfill layer creates a "beam effect," which actively pre-supports a larger area of ​​loose rock and soil above the tunnel arch, significantly enhancing the self-stability of the excavation face, effectively controlling settlement, and providing advanced protection for safe tunnel excavation.

[0029] In this embodiment, the backfill layer 9 is made of C20 concrete.

[0030] Using C20 concrete as the backfill material provides sufficient structural strength and stability while also being economical. Its fluidity and self-compacting properties facilitate construction and filling, enabling the rapid formation of a robust load-bearing structure that effectively transfers and distributes the superstructure load.

[0031] In this embodiment, the tunnel structure includes an initial support 1 and a secondary lining 2. The initial support 1 is placed on the outer periphery of the secondary lining 2 and connected to the reinforcement structure.

[0032] The composite lining structure, consisting of initial support and secondary lining, serves a clear purpose. The initial support quickly seals the rock face and controls deformation; the secondary lining acts as a safety reserve and a permanent load-bearing structure. Both are effectively connected to the superstructure, ensuring the continuity of the load transfer path and the overall durability of the structure.

[0033] In this embodiment, the bridge structure includes an arch bridge structure 4, an arch base 5, anchor bolts 6, and a filling layer 7. The arch base 5 is placed at both ends of the arch bridge structure 4, and the filling layer 7 is used to fill the space between the arch bridge structure 4 and the tunnel structure. The anchor bolts 6 are placed on both sides of the filling layer 7 for reinforcement.

[0034] This bridge ingeniously applies the mechanical advantages of arch bridges to crossing karst caves. The arch structure transforms vertical loads into axial pressure, resulting in a rational stress distribution; the arch foundation provides reliable support; the infill layer transfers loads and levels the surface; and the anchor bolts strengthen the connection between the bridge structure and the surrounding rock mass, preventing lateral displacement, thus forming a well-defined, stable, and reliable crossing system.

[0035] In this embodiment, the filling layer 7 is made of C30 concrete.

[0036] The filling layer uses higher grade C30 concrete, which ensures that this key load-bearing area has sufficient compressive strength and stiffness, effectively transferring the load of the upper tunnel structure to the lower arch bridge structure, avoiding stress concentration, and ensuring the long-term stability of the tunnel-bridge junction.

[0037] In this embodiment, the detour tunnel 11 is connected to the karst cave 13 through the detour tunnel connecting channel 12.

[0038] The establishment of dedicated connecting channels makes the connection between the bypass tunnel and the karst cave more efficient and controllable. This not only facilitates the rapid clearing and transportation of accumulated materials during construction, but also provides a convenient passage for drainage, dredging, inspection, and maintenance of the karst cave during operation, thereby improving the maintainability of the structure throughout its entire life cycle.

[0039] Example 2:

[0040] A method for constructing a tunnel-embedded arch bridge-type spanning structure, wherein the spanning structure includes the spanning structure described in Embodiment 1, and the construction method includes the following steps:

[0041] Step 1, Treatment of weak deposits: Remove weak deposits 16 from the tunnel face 14 and strengthen monitoring and measurement; excavate the detour pilot tunnel 11 and the detour pilot tunnel connecting passage 12; after removing weak deposits 16 from the top of the tunnel to the top surface of the arch support 3, backfill with C20 concrete to form the backfill layer 9; then lay the buffer layer 10 and do a good job of drainage and dredging.

[0042] Step 2: Expand the excavation from tunnel face 14, construct the large pipe shed 8, and then construct the arch support 3;

[0043] Step 3, Excavation of foundation pit and construction of arch seat: Clear the weak deposits 16 within the bridge area to the excavation line, protect the slope of the foundation pit, and install anchor bolts 6; after binding the pre-embedded steel bars of the arch seat foundation 5 and the arch bridge structure 4, pour the arch seat foundation 5.

[0044] Step 4: Construction of the arch bridge structure: Tie the reinforcing bars of the arch bridge structure 4. The arch bridge structure 4 can be poured symmetrically only after the strength of the arch foundation 5 reaches 95% of the design value.

[0045] Step 5, Concrete filling: After the elastic modulus and strength of the arch bridge structure 4 reach 100% of the design value, C30 concrete can be used for filling to obtain filling layer 7.

[0046] Step 6, Tunnel Lining Construction: After the C30 concrete filling layer 7 reaches 100% of the design modulus and strength, the initial support 1 and secondary lining 2 shall be constructed.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tunnel-embedded arch bridge-type spanning structure, characterized in that: A meandering guide tunnel (11) is connected to one side of the cave (13). The meandering guide tunnel (11) serves as a channel for cleaning and transporting the accumulated materials inside the cave (13). The crossing structure includes a tunnel structure, a bridge structure, and a reinforcement structure. The cave (13) is provided with the reinforcement structure, tunnel structure, and bridge structure from top to bottom.

2. The tunnel-embedded arch bridge-type spanning structure according to claim 1, characterized in that: The reinforcement structure includes a buffer layer (10), a backfill layer (9), and a protective arch (3) arranged sequentially from top to bottom, with the protective arch (3) connected to the upper part of the tunnel structure.

3. The tunnel-embedded arch bridge-type spanning structure according to claim 2, characterized in that: The backfill layer (9) is provided with a large pipe shed (8), which is inclined along the extension direction of the tunnel structure.

4. The tunnel-embedded arch bridge-type spanning structure according to claim 2, characterized in that: The backfill layer (9) is made of C20 concrete.

5. A tunnel-embedded arch bridge-type spanning structure according to any one of claims 1-4, characterized in that: The tunnel structure includes an initial support (1) and a secondary lining (2). The initial support (1) is placed on the outer periphery of the secondary lining (2) and connected to the reinforcement structure.

6. A tunnel-embedded arch bridge-type spanning structure according to any one of claims 1-4, characterized in that: The bridge structure includes an arch bridge structure (4), an arch foundation (5), anchors (6), and a filling layer (7). The arch foundation (5) is placed at both ends of the arch bridge structure (4). The filling layer (7) is filled between the arch bridge structure (4) and the tunnel structure. The anchors (6) are placed on both sides of the filling layer (7) for reinforcement.

7. The tunnel-embedded arch bridge-type spanning structure according to claim 6, characterized in that: The filling layer (7) is made of C30 concrete.

8. A tunnel-embedded arch bridge-type spanning structure according to any one of claims 1-4, characterized in that: The detour tunnel (11) is connected to the karst cave (13) through the detour tunnel connecting channel (12).

9. A method for constructing a tunnel-embedded arch bridge-type spanning structure, characterized in that: The spanning structure includes the spanning structure according to any one of claims 1-8, and the construction method includes the following steps: Step 1, Treatment of weak deposits: Remove weak deposits (16) from the tunnel face (14) and strengthen monitoring and measurement; excavate the detour pilot tunnel (11) and the detour pilot tunnel connecting passage (12), remove weak deposits (16) from the top of the tunnel to the top surface of the arch support (3), and backfill with C20 concrete to form a backfill layer (9), then lay a buffer layer (10), and do a good job in drainage and dredging. Step 2: Expand the excavation from the tunnel face (14), construct the large pipe shed (8), and then construct the arch support (3). Step 3, Excavation of the foundation pit and construction of the arch seat: Clear the soft deposits (16) within the bridge area to the excavation line, protect the slope of the foundation pit, and install anchor bolts (6); after binding the arch seat foundation (5) and the pre-embedded steel bars of the arch bridge structure (4), pour the arch seat foundation (5). Step 4: Construction of the arch bridge structure: Tie the reinforcing bars of the arch bridge structure (4). The arch bridge structure (4) can be poured symmetrically only after the strength of the arch foundation (5) reaches 95% of the design value. Step 5, concrete filling: After the elastic modulus and strength of the arch bridge structure (4) reach 100% of the design value, C30 concrete can be used to fill the bridge to obtain the filling layer (7). Step 6, Tunnel Lining Construction: After the elastic modulus and strength of the C30 concrete filling layer (7) reach 100% of the design value, the initial support (1) and secondary lining (2) are constructed.

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