Overlapped composite lining structure and construction method

Abstract

The laminated composite lining structure comprises a primary sprayed concrete layer, a secondary sprayed concrete layer and a lining layer, the waterproof layer is sprayed on the primarily sprayed concrete layer; the at least two steel-concrete prefabricated assemblies can be spliced and mounted into arched or circular supporting structures matched with the tunnel, and the supporting structures are arranged at intervals in the length direction of the tunnel and tightly attached to the waterproof layer; the steel reinforcement framework is arranged in the tunnel and connected with the supporting structure to form a whole; and concrete is molded, and the steel reinforcement framework, the waterproof layer and the supporting structure are poured. By means of the steel-concrete prefabricated assembly, a traditional independently-constructed steel arch and sprayed concrete supporting mode is replaced, and the industrial problems that the viscosity of the steel arch and sprayed concrete is poor, and cavities are likely to be generated are solved fundamentally. The reinforced concrete prefabricated assembly can directly replace a steel member to be used, and meanwhile it needs to be noted that the outer surface of the prefabricated concrete layer needs to be roughened, so that in the waterproof layer spraying link, sprayed concrete and the roughened prefabricated concrete layer have better adhesion. The reinforced concrete prefabricated assembly and the molded concrete layer form a whole with coordinated stress through the connecting ribs, the bearing capacity and the waterproof performance of the structure are improved, and the problems that a traditional lining structure is not coordinated in stress and poor in waterproof effect are solved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a composite lining structure and construction method. Background Technology

[0002] In recent years, with the continuous development of tunnel and underground engineering construction in my country towards deeper levels, underground transportation infrastructure construction has become an indispensable and important part of the modern travel system. Among them, tunnels play a crucial role in transportation engineering. However, with the increasing mileage of tunnel construction year by year, material consumption and project costs remain high, and problems such as lining structure cracking and water damage are becoming increasingly prominent. This phenomenon is closely related to the tunnel structural form and the materials used.

[0003] Currently, composite lining structures are commonly used in tunnel engineering, mainly consisting of primary support lining and secondary lining. Primary support lining often employs a combination of shotcrete and steel arch support, while secondary lining typically uses cast-in-place reinforced concrete. However, traditional shotcrete and steel arch support requires a large amount of shotcrete to fill the gaps around the steel arch. Because the adhesion between the steel arch and shotcrete is poor, the concrete tends to fall during shotcreting, leading to a significant increase in shotcrete usage in practical applications. This creates voids between the shotcrete layer and the steel arch, resulting in increased construction costs, resource waste, and potential construction quality problems. Furthermore, the traditional "primary support + waterproofing membrane + secondary lining" support system also suffers from structural stress incoordination and poor waterproofing, severely impacting the overall load-bearing capacity and effective waterproofing performance of the tunnel support structure. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of large amount of shotcrete, uncoordinated structural stress, and poor waterproofing effect in the traditional "initial support + waterproof board + secondary lining" support system, and to propose a composite lining structure and construction method.

[0005] The objective of this invention can be achieved through the following technical solutions: A composite lining structure, comprising: Initial shotcrete layer; A waterproof layer is sprayed onto the initial sprayed concrete layer; At least two precast reinforced concrete components can be spliced ​​together to form an arched or circular support structure adapted to the tunnel, the support structure being spaced apart along the length of the tunnel and closely attached to the waterproof layer; A steel reinforcement frame is installed inside the tunnel and connected to the supporting structure to form an integral whole; The steel reinforcement cage, the waterproof layer, and the supporting structure are poured to form a cast-in-place concrete layer.

[0006] This invention replaces the traditional independently constructed steel arch frame + shotcrete support method with precast steel-concrete components, fundamentally solving the industry problem of poor adhesion between steel arch frame and shotcrete, which easily leads to voids in actual engineering projects.

[0007] Because this precast steel-concrete component can directly replace steel components, and it is important to note that the outer surface of the precast concrete layer needs to be roughened, so that the sprayed concrete and the roughened precast concrete layer have better adhesion during the waterproofing process.

[0008] It is also worth mentioning that the concrete grade in the precast steel-concrete components can be increased individually, which can increase the strength of individual support structures, thereby strengthening the support strength in the tunnel and avoiding the additional costs incurred by using large quantities of high-grade concrete.

[0009] As a further aspect of the present invention: the precast steel-concrete assembly includes: Support components; A concrete layer is provided along the length of the support member, and the upper flange and web of the support member are embedded in the concrete layer.

[0010] As a further aspect of the present invention: the composite lining structure further includes at least two connecting bars disposed on the lower flange of the support member, and the steel reinforcement skeleton is connected to the support member through the connecting bars.

[0011] The concrete covering layer of the precast steel-concrete components forms a reliable bond with the subsequent cast-in-place concrete layer. Combined with connecting bars, the precast steel-concrete components are firmly connected to the steel reinforcement skeleton, making the entire composite lining structure a cohesive whole that can withstand stress. This effectively avoids the problem of inconsistent deformation and stress in traditional lining structures and significantly improves the structural safety and durability of the tunnel during long-term operation.

[0012] As a further embodiment of the present invention: the support member is an I-beam, an H-beam, or a steel-concrete composite structure.

[0013] As a further embodiment of the present invention: both ends of the support member are provided with end plates, and locking members are provided on the end plates.

[0014] As a further aspect of the present invention: the steel reinforcement cage includes main bars, longitudinal bars and hook bars, and the main bars, longitudinal bars and hook bars are tied together, and the connecting bars are connected and fixed to the main bars.

[0015] A construction method for a composite lining structure includes the following steps: S1. Apply initial shotcrete layer to the exposed surrounding rock surface inside the tunnel. S2. After the initial sprayed concrete layer reaches the design strength, a waterproof layer is sprayed on its inner surface. S3. After the thickness and strength of the waterproof layer meet the design requirements, install the precast steel-concrete components symmetrically and orderly from the bottom of the tunnel to the top of the arch. Connect the end plates of adjacent components with locking devices and complete the longitudinal connection of the precast steel-concrete components to improve stability. S4. Fix the connecting bars at intervals on the lower flange of the support of the precast steel-concrete component, tie the steel reinforcement cage and fix the main bars and connecting bars. S5. After the formwork is erected, a concrete layer is poured to enclose the precast steel-concrete components, steel reinforcement frame and waterproof layer, forming a composite lining structure.

[0016] As a further aspect of the present invention: in S, the initial sprayed concrete layer is made of ordinary concrete, high-density concrete, fiber concrete or polymer concrete.

[0017] During on-site construction, the precast steel-concrete components are easy to install, quickly spliced ​​using end-plate locking devices, and improved support efficiency through longitudinal connections. Subsequent processes such as rebar tying and formwork erection in the cast-in-place lining can proceed without waiting for the lengthy curing process of traditional wire mesh + steel structure + shotcrete. Less shotcrete is used during construction, significantly reducing the time required for the shotcreting process and noticeably improving the working environment. Furthermore, the precast steel-concrete components and the cast-in-place concrete layer form a cohesive whole, enhancing structural load-bearing capacity and waterproofing performance, effectively suppressing surrounding rock deformation, and providing a solid foundation for the long-term safe operation of the tunnel. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 This is a structural schematic diagram of a precast reinforced concrete component; Figure 2 This is a schematic diagram showing the position of the connecting bars on the precast steel-concrete component; Figure 3 and Figure 5 It is a diagram showing the positional relationship between precast steel-concrete components, steel reinforcement cage, and cast-in-place concrete layer; Figure 4 This is a structural diagram of the steel reinforcement cage; Figure 6 This is a structural diagram of the support member in another embodiment; Figure 7 This is a flowchart of the construction steps for the application.

[0020] In the diagram: 1. Initial shotcrete layer; 2. Waterproof layer; 3. Precast reinforced concrete component; 31. Concrete covering layer; 32. Support component; 33. End plate; 4. Connecting bar; 5. Reinforcing steel cage; 51. Main bar; 52. Longitudinal bar; 53. Hook bar; 6. Cast-in-place concrete layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 Precast reinforced concrete components, including: At least two support members 32, which can be spliced ​​together to form an arched or circular support structure adapted to the tunnel; The concrete layer 31 is provided along the length of the support member 32, and the upper flange and web of the support member 32 are embedded in the concrete layer 31.

[0023] Both ends of the support member 32 are provided with end plates 33, and locking elements are provided on the end plates 33.

[0024] In this embodiment, the precast steel-concrete component can directly replace the steel component. It should be noted that the outer surface of the concrete layer 31 needs to be roughened so that the sprayed concrete and the roughened concrete layer have better adhesion during the waterproofing process.

[0025] Please see Figure 1-5 This application relates to a composite lining structure, which, from the outside to the inside, consists of a shotcrete layer 1, a waterproof layer 2, a precast steel-concrete component 3, connecting bars 4, a steel reinforcement skeleton 5, and a cast-in-place concrete layer 6.

[0026] The outer surface of the initial shotcrete layer 1 is in close contact with the surrounding rock of the tunnel, making the uneven surface of the surrounding rock smooth.

[0027] A waterproof layer 2 is sprayed onto the inner surface of the initial sprayed concrete layer 1 to achieve waterproof and seepage-proof effects.

[0028] The precast steel-concrete component 3 is in contact with the waterproof layer 2 and consists of a concrete covering layer 31, a support member 32 and an end plate 33. The upper flange and part of the web of the support member 32 are embedded in the concrete covering layer 31, and the lower flange surface of the support member 32 is connected to the connecting bar 4.

[0029] The steel reinforcement cage 5 is connected to the support member 32 through the connecting bars 4, so that the precast steel-concrete component 3 and the steel reinforcement cage 5 form an integral whole.

[0030] The cast-in-place concrete layer 6 is formed by casting the precast steel-concrete components 3 and the steel reinforcement skeleton 5 into a whole, forming a composite lining structure.

[0031] A waterproof layer 2 was added between the initial shotcrete layer 1 and the precast steel-concrete component 3. The steel reinforcement cage 5 was directly connected to the precast steel-concrete component 3 through connecting bars 4. Finally, the precast steel-concrete component 3 and the steel reinforcement cage 5 were cast together by molding to form a whole. This is significantly different from the previous structure of initial support lining + waterproof board + secondary lining. This embodiment emphasizes the integrity of the lining structure and solves the problems of inconsistent deformation and stress and waterproofing and seepage prevention in traditional lining structures.

[0032] See Figure 1 The precast reinforced concrete component 3 can be prefabricated in a factory and manufactured using methods such as molding and 3D printing, including but not limited to conventional concrete, high-strength concrete, lightweight concrete, self-compacting concrete, and fiber-reinforced concrete. End plates 33 are provided at both ends of the support member 32. A concrete covering layer 31 covers the outer flange and part of the web of the support member 32, with the remaining portion exposed. To improve the integrity of the concrete covering layer 31 and the support member 32, studs can be provided on the surface of the support member 32.

[0033] See Figure 2 Connecting ribs 4 are provided at certain intervals on the inner flange surface of the support member 32, and the middle part of the connecting ribs 4 is connected to the support member 32.

[0034] Please see Figure 3 and Figure 4 The steel reinforcement cage 5 includes four main bars 51, several longitudinal bars 52, and hook bars 53, which are constrained and fixed together. The two outer main bars 51 are connected to the two ends of the connecting bars 4, so that the steel reinforcement cage 5 and the precast steel-concrete component 3 form an integral whole. The connecting bars 4 mainly serve the function of connection, and other forms of connectors can be used instead, such as U-shaped bars, L-shaped bars, T-shaped bars, figure-eight bars, zigzag bars, etc. This embodiment only uses the connecting bars 4 as an example.

[0035] Please see Figure 6 This invention relates to two other prefabricated lining structures, but is not limited to these two.

[0036] Figure 6 It is a precast lining structure composed of steel-concrete composite pipe and concrete cladding layer 31, and Figure 6 The supporting member 32 is a steel-concrete composite tube, with its upper surface and some sides covered by a concrete covering layer 31, while the remaining parts are exposed. To improve the integrity of the precast lining structure, studs can be installed on the surface of the steel-concrete composite tube.

[0037] In addition to steel pipe concrete and I-beams, support member 32 can also be H-beams. It is important to note that although the cross-section of H-beams is similar to that of I-beams, their rigidity and dimensions are not the same.

[0038] like Figure 1-7As shown in the figure, the construction method of the composite lining structure described in this application mainly includes the following steps: S1. Determine the structural form and design parameters of the lining structure based on the geological conditions and construction parameters of the tunnel, including the selection and design of precast steel-concrete components 3 and steel reinforcement skeleton 5, lining thickness, node distribution, selection of waterproof layer 2, etc. S2. After the tunnel is excavated, apply a certain thickness of initial shotcrete layer 1 to the exposed surrounding rock surface in a timely manner. The quality should be dense, flat, and free from cracks, peeling, hollowing and water seepage. Then, spray a waterproof layer 2 on the inner surface of the initial shotcrete layer 1. S3. After the thickness and strength of the waterproof layer 2 meet the design requirements, install the precast steel-concrete components 3 sequentially and orderly on the surface of the waterproof layer 2, connect the end plate connection holes of adjacent components with hexagonal bolts, and make longitudinal connections to the precast lining to improve the stability of the support structure. S4. After the precast lining is installed, the connecting bars 4 are fixed at certain intervals on the lower surface of the flange of the support member 32 in the precast lining. Then, the steel reinforcement cage 5 is tied, the formwork is built and the concrete is poured, so that the precast lining and the cast-in-place lining form a composite lining structure, ensuring the integrity and safety of the tunnel lining structure. S5. For local voids and hollow areas, pressure-filled concrete can be used for repair, so that the precast lining and cast-in-place lining form an integrated composite lining structure.

[0039] It should be emphasized that the construction method of the composite lining structure described in this embodiment aims to construct a permanent tunnel lining structure with high load-bearing capacity, good waterproof performance, and strong integrity through the manufacturing process of "standardized prefabricated lining + high-quality cast-in-place lining".

[0040] Based on geological conditions such as surrounding rock grade, groundwater layer, and geostress, as well as factors such as tunnel depth, cross-sectional shape and size, and construction methods, the lining type, structural parameters, block design, and selection of waterproof layer materials are rationally determined.

[0041] After tunnel excavation, and after addressing over- and under-excavation, a wet-spraying robotic arm should be used promptly to ensure close adhesion between the initial shotcrete layer 1 and the surrounding rock. The spraying should follow a segmented, bottom-up sequence, with flatness controlled within 5mm / 2m to provide a good base surface for subsequent waterproofing layer 2 construction. Density can be tested using a rebound hammer or core sampling. Suitable shotcrete materials include early-strength concrete, high-density concrete, fiber-reinforced concrete, and polymer concrete.

[0042] After the waterproof layer 2 is completed, the precast lining components are transported to the tunnel working face using a dedicated transport vehicle. Then, the components are lifted smoothly and vertically using hydraulic clamps on a multi-functional work platform. During the lifting process, protective measures must be taken to prevent the edges of the components from hitting the completed waterproof layer 2. Starting from the bottom of the tunnel, the components are installed symmetrically towards the sides and the top of the tunnel. Operators guide the components slowly towards the installation position, using their own weight to initially align them with the tunnel contour. When the end plates 33 of two adjacent components are about to fit together, a designated person uses positioning pins (or guide rods) to insert into the connection holes on the end plates for precise positioning, ensuring all bolt holes are aligned. After the positioning pins are in place, high-strength hexagonal bolts as specified in the design are used for connection. After completing the circumferential connection of one ring of lining, it is immediately longitudinally connected to the previously installed ring of lining. Throughout the installation process, a total station or laser target should be used to monitor the three-dimensional coordinates of each component in real time after it is in place, ensuring that its planar position, elevation, and verticality deviations are all controlled within the design allowable range.

[0043] Strictly follow the design drawings, arrange the connecting bars 4 circumferentially along the support member 32, with a spacing typically controlled between 300-500mm. In critical areas (such as arch foot and near joints), the spacing needs to be appropriately increased. Use double-sided staggered welding to firmly weld the horizontal sections of the connecting bars 4 to the lower surface of the flange of the support member 32. The welding length must meet the specifications, ensuring a full weld, free of slag inclusions and air bubbles. After welding, remove the slag and inspect the weld. Using the precast lining inner wall as a reference plane, strictly follow the design drawings to tie the internal main bars 51, longitudinal bars 52, and hook bars 53, forming a complete cast-in-place lining steel reinforcement skeleton 5. During the tying process, the newly laid steel reinforcement skeleton 5 must be reliably connected to the pre-installed connecting bars 4. Ensure that the specifications, spacing, row spacing, lap length, and protective layer thickness of the reinforcing bars fully meet the design requirements, guaranteeing the structural performance of the cast-in-place concrete.

[0044] To ensure a dense pour, especially in areas with dense reinforcement and those difficult to observe behind precast linings, high-flowability, self-compacting, micro-expansion concrete should be used. Starting from the arch footings on both sides of the tunnel, pour the concrete symmetrically and continuously in layers upwards to the arch crown. While pouring to the arch crown, observe through pre-reserved grouting holes to ensure the concrete fills the entire chamber. A formwork-based grouting technique can be used at the arch crown, with supplementary grouting performed after pouring to completely eliminate the risk of voids at the arch crown.

[0045] Through the above construction process, the precast steel-concrete components 3 and the cast-in-place concrete layer 6 are tightly combined to form a composite lining structure. This structure fully utilizes the advantages of precast components, such as rapid ring formation and immediate load-bearing capacity, while also possessing the advantages of cast-in-place concrete structures, such as good integrity, high waterproof reliability, and strong adaptability to complex geological conditions, thus jointly ensuring the long-term safety and stability of the tunnel lining structure.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A composite lining structure, characterized in that, include: Initial shotcrete layer (1); Waterproof layer (2) is sprayed onto the initial sprayed concrete layer (1); At least two precast steel-concrete components (3) can be spliced ​​and installed into an arched or circular support structure adapted to the tunnel, the support structure being spaced apart along the length of the tunnel and closely attached to the waterproof layer (2); A steel reinforcement frame (5) is installed inside the tunnel and connected to the supporting structure to form an integral whole; The steel reinforcement cage (5), the waterproof layer (2), and the supporting structure are poured to form a cast-in-place concrete layer (6).

2. The composite lining structure according to claim 1, characterized in that, The precast steel-concrete assembly (3) includes: Support component (32); A concrete layer (31) is provided along the length of the support member (32), and the upper flange and web of the support member (32) are embedded in the concrete layer (31).

3. The composite lining structure according to claim 2, characterized in that, The composite lining structure further includes at least two connecting bars (4) disposed on the lower flange of the support member (32), and the steel reinforcement skeleton (5) is connected to the support member (32) through the connecting bars (4).

4. The composite lining structure according to claim 2, characterized in that, The support member (32) is an I-beam or a steel-concrete composite tube.

5. The composite lining structure according to claim 2, characterized in that, Both ends of the support member (32) are provided with end plates (33), and locking elements are provided on the end plates (33).

6. The composite lining structure according to claim 1, characterized in that, The steel reinforcement cage (5) includes main bars (51), longitudinal bars (52) and hook bars (53), and the main bars (51), longitudinal bars (52) and hook bars (53) are tied together, and the connecting bars (4) are connected to the main bars (51).

7. A construction method for a composite lining structure, characterized in that, Includes the following steps: S1. Apply initial shotcrete layer to the exposed surrounding rock surface inside the tunnel. S2. After the initial sprayed concrete layer reaches the design strength, a waterproof layer is sprayed on its inner surface. S3. After the thickness and strength of the waterproof layer meet the design requirements, install the precast steel-concrete components symmetrically and orderly from the bottom of the tunnel to the top of the arch. Connect the end plates of adjacent components with locking devices and complete the longitudinal connection of the precast steel-concrete components to improve stability. S4. Fix the connecting bars at intervals on the lower flange of the support of the precast steel-concrete component, tie the steel reinforcement cage and fix the main bars and connecting bars. S5. After the formwork is erected, the cast-in-place concrete layer is poured to enclose the precast steel-concrete components, steel reinforcement frame and waterproof layer, forming a composite lining structure.

8. The construction method of a composite lining structure according to claim 7, characterized in that, In S1, the initial shotcrete layer is made of ordinary concrete, high-density concrete, fiber-reinforced concrete, or polymer concrete.

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