A multi-layer composite shield tunnel segment based on fiber concrete and a preparation method thereof

Abstract

The application provides a kind of multilayer composite shield tunnel segment based on fiber concrete and a preparation method thereof.The segment includes an ECC-NC inner protective layer, a segment structure layer and a UHPC outer protective layer.The ECC-NC inner protective layer is formed by embedding ECC blocks in a common concrete grid, the segment structure layer is made of ordinary reinforced concrete, and the UHPC outer protective layer is composed of basalt fiber grid sheet and ultra-high performance concrete.The ECC blocks and the common concrete form a bubble film groove type joint surface, and the joint surface between the UHPC outer protective layer and the segment structure layer is composed of a bubble film groove type joint surface and a mesh type joint surface.The segment is made by a small number of process modifications such as reverse preparation of ECC blocks, segment mold upper cover plate pasting bubble film, etc., on the basis of conventional preparation methods.The application combines the high crack resistance, impermeability and durability of UHPC with the good fire resistance and blast resistance of ECC, improves the performance of the segment, reduces the impact of cost, is simple to prepare, can be well combined with conventional preparation processes, and has the potential for large-scale promotion.

Description

Technical Field

[0001] This invention relates to the field of underground engineering, specifically to a multi-layer composite shield tunnel segment made of fiber-reinforced concrete and its preparation method. Background Technology

[0002] With the rapid development of infrastructure construction in my country, the number of shield tunnels being built is constantly increasing, and the workload is growing rapidly. As the main lining material in the shield tunneling process, shield tunnel segments have a significant impact on the tunnel's formation and subsequent operational quality.

[0003] Currently, underwater shield tunnels in my country are developing towards larger cross-sections and deeper locations. The resulting challenges of greater burial depth and higher soil and water pressure place higher demands on the safety and durability of the tunnel segments. Conventional concrete shield tunnel segments are prone to cracking and damage during production, construction, and operation, which significantly impacts the structural performance and durability of the tunnel after completion. Furthermore, in the event of a fire or explosion during operation, conventional concrete can rapidly deteriorate, leading to a rapid decrease in tunnel safety and irreversible damage.

[0004] With advancements in building materials technology, fiber-reinforced cementitious composites have seen significant development. The incorporation of fibers plays a crucial role in improving the toughness of cementitious materials. Research has revealed that fiber-reinforced cementitious composites are high-performance materials exhibiting high toughness, high ductility, excellent tensile strength, and superior crack control. However, due to the vastly different properties of ordinary fiber-reinforced concrete, using the same type of fiber-reinforced concrete in shield tunnel segments often fails to simultaneously meet all the performance requirements of the segments, while also significantly increasing costs. Therefore, single-fiber concrete segments are relatively rare in practical applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a multi-layer composite shield tunnel segment based on fiber-reinforced concrete and its preparation method, which effectively improves tunnel durability, impermeability, crack resistance, blast resistance, and impact resistance, exhibiting good durability while maintaining controllable costs.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] A multi-layer composite shield tunnel segment based on fiber-reinforced concrete includes: an ECC-NC inner protective layer, a segment structure layer, and a UHPC outer protective layer;

[0008] The ECC-NC inner protective layer is located on the lower surface of the entire multi-layer composite shield tunnel segment and is composed of ECC blocks and ordinary concrete grid layer.

[0009] The ordinary concrete grid layer is composed of horizontal and vertical concrete ribs, which cover the lower surface of the multi-layer composite shield tunnel segments.

[0010] The ECC block is embedded in the grid position of the ordinary concrete grid layer; the ECC block is composed of fiber cement-based composite material and structural reinforcement, the structural reinforcement is arranged in a grid pattern in the ECC block, and both ends are provided with upward 90° hooks that extend out of the side of the ECC block; the extended portions of the structural reinforcement of adjacent ECC blocks overlap each other; the upper surface and side of the ECC block are a first bubble film groove interface, and the joint surface between the ECC block and the ordinary concrete grid layer is a bubble film groove joint surface;

[0011] The outer protective layer of the UHPC is made of ultra-high performance concrete and arc-shaped basalt fiber mesh.

[0012] The bonding surface between the UHPC outer protective layer and the tube structure layer consists of two parts: a bubble film groove bonding surface and a mesh bonding surface.

[0013] The bubble film groove joint surface is located on both sides of the arc length direction of the multi-layer composite shield tunnel segment.

[0014] The grid-like joint surface is located in the middle region of the arc length direction of the multi-layer composite shield tunnel segment.

[0015] The segment structure layer is made of polypropylene fiber ordinary concrete and ribbed steel cage, and the groove diameter of the bubble film groove joint surface is larger than the minimum aggregate particle size of the segment structure layer concrete.

[0016] The thickness of the segment structure layer is the thickness calculated based on the stress requirements minus the thickness of the UHPC outer protective layer.

[0017] The ECC block is a cuboid structure with a length of 400mm, a width of 200mm, and a height of 50mm.

[0018] The outer protective layer of the UHPC is 50 mm thick.

[0019] This invention further discloses a method for preparing multi-layer composite shield tunnel segments based on fiber-reinforced concrete, comprising the following steps:

[0020] Step 1: Make an ECC block template and paste the first bubble wrap inside the ECC block template to form a grooved interface of the first bubble wrap on the upper surface and side of the ECC block.

[0021] Step 2: Reverse the arrangement of the structural reinforcement bars so that the end hooks face downwards; pour the fiber cement-based composite material; after curing and hardening, remove the formwork to form the reversed ECC blocks; store the ECC blocks upright.

[0022] Step 3: Distribute and evenly arrange the ECC blocks on the entire arc surface of the bottom of the shield tunnel segment steel formwork, leaving a certain gap between the ECC blocks to form a concrete mesh structure, which increases the bonding performance between the two types of concrete.

[0023] The structural reinforcement bars overlap each other;

[0024] Step 4: Place the ribbed steel cage on the ECC block;

[0025] Step 5: Attach the second bubble wrap to the lower surface of the top cover plate of the shield tunnel segment steel formwork, and then cover it with the cover plate;

[0026] Step Six: Pour polypropylene fiber ordinary concrete into the steel mold and vibrate it. The exposed part of the upper surface is initially smoothed. The exposed part of the upper surface is roughened in the horizontal and vertical directions to form the mesh interface. Then, it is cured.

[0027] Step 7: After the polypropylene fiber ordinary concrete has initially set, open the cover plate. A second bubble film groove interface is formed at the contact area between the upper surface of the pipe segment and the pipe segment. Arrange the arc-shaped basalt fiber mesh sheet on the upper part and apply UHPC concrete to form the outer protective layer of UHPC.

[0028] Step 8: Use steam curing method for curing. After complete hardening, the multi-layer composite shield tunnel segment based on fiber concrete is formed.

[0029] In step three, a gap of 100mm is maintained between the ECC blocks.

[0030] Beneficial effects:

[0031] (1) The present invention adopts multi-layer composite shield tunnel segments, which combine fiber concrete with different properties and arrange them differently. The outer surface is made of UHPC layer to achieve high crack resistance, high impermeability and high durability. The inner surface layer is arranged with precast ECC blocks. In the event of a fire, the internal fibers can quickly vaporize and absorb heat, and form fine gaps to release stress. The fine gaps here refer to the formation of fiber materials inside the ECC blocks after vaporization, thereby protecting the structural layer of the tunnel segment and greatly improving the fire resistance and explosion resistance.

[0032] (2) The structural load-bearing layer in the middle of the present invention still mainly uses polypropylene fiber ordinary concrete, which has a small impact on cost. At the same time, based on the mature segment manufacturing process, a small number of process improvements can achieve efficient manufacturing and have economic competitiveness.

[0033] The use of bubble film grooved and mesh-type bonding surfaces to connect different layers of fiber-reinforced concrete ensures reliable performance. The combined use of these two bonding surface methods significantly increases the effective bonding area between ordinary concrete and UHPC, resulting in high bonding strength and greatly improving the overall performance of the composite shield tunnel segments. Simultaneously, the effective bonding between the two different types of concrete allows for greater utilization of the UHPC's properties, enhancing the shield tunnel segments' impermeability, crack resistance, and durability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a multi-layer composite shield tunnel segment based on fiber-reinforced concrete.

[0035] Figure 2 This is a schematic diagram of the bottom of a multi-layer composite shield tunnel segment based on fiber-reinforced concrete.

[0036] Figure 3 This is a schematic diagram of the ECC block connection;

[0037] Figure 4 Schematic diagram of ECC block template;

[0038] Figure 5 This is a schematic diagram of the cross-section of a multi-layer composite shield tunnel segment based on fiber-reinforced concrete.

[0039] Figure 6 This is a view of the bottom surface of the cover plate of the rigid table mold;

[0040] Figure 7 This is a schematic diagram of the bonding surface layer of NC-UHPC.

[0041] Among them, 1 is the inner protective layer of ECC-NC; 2 is the segment structure layer; 3 is the outer protective layer of UHPC; 4 is the ECC block; 5 is the ordinary concrete grid layer; 6 is the structural reinforcement; 7 is the first bubble film groove interface; 8 is the first bubble film; 9 is the ribbed steel cage; 10 is the arc-shaped basalt fiber mesh sheet; 11 is the second bubble film; 12 is the second bubble film groove interface; and 13 is the mesh interface. Detailed Implementation

[0042] The technical solution of the present invention will be described in detail below with reference to the schematic diagram, but the scope of protection of the present invention is not limited to the examples described.

[0043] A multi-layer composite shield tunnel segment based on fiber-reinforced concrete, such as Figure 1 As shown, it includes an inner protective layer 1 of ECC-NC, a segment structure layer 2, and an outer protective layer 3 of UHPC.

[0044] like Figure 2As shown, in the inner protective layer 1 of ECC-NC, the ECC block 4 is embedded in the grid position of the ordinary concrete grid layer 5 with a gap of 100mm.

[0045] like Figure 3 As shown, the ECC block 4 is composed of fiber cementitious composite material (ECC) and structural reinforcement 6. The structural reinforcement is arranged in a grid pattern in the ECC block, with upward 90° hooks at both ends extending out of the side of the ECC block. The upper surface and side of the ECC block form a first bubble film groove interface 7, and the extended portions of the structural reinforcement of adjacent ECC blocks overlap each other.

[0046] like Figure 4 As shown, the first bubble film 8 is pasted inside the ECC block template. The diameter of the first bubble film is larger than the minimum aggregate particle size of the concrete in the segment structure layer.

[0047] like Figure 5 As shown, the segment structure layer 2 is made of polypropylene fiber ordinary concrete and ribbed steel cage 9. The UHPC outer protective layer 3 is made of ultra-high performance concrete (UHPC) and arc-shaped basalt fiber mesh sheet 10.

[0048] like Figure 6 As shown, the second bubble film groove interface 12 between the segment structure layer 2 and the UHPC outer protective layer 1 is made by pasting the second bubble film 11 on the lower surface of the top cover plate of the shield tunnel segment steel mold. The diameter of the second bubble film is larger than the minimum aggregate particle size of the segment structure layer concrete.

[0049] like Figure 7 As shown, the tube structure layer 2 and the UHPC outer protective layer 1 adopt a second bubble film groove interface 12 and a mesh interface 13.

[0050] The above-mentioned method for preparing multi-layer composite shield tunnel segments based on fiber-reinforced concrete includes the following steps:

[0051] Step 1: Make a block template according to the ECC block 4 specification, and paste the first bubble wrap 8 inside the block template;

[0052] Step 2: Reverse the arrangement of the structural reinforcement 6 so that the end hooks face downwards; pour the fiber cement-based composite material; after curing and hardening, demold to form the reversed ECC block 4; store the ECC block 4 upright.

[0053] Step 3: Distribute and evenly arrange ECC blocks 4 on the entire arc surface of the bottom of the shield tunnel segment steel formwork, with a certain gap between the ECC blocks 4, and the structural reinforcement 6 overlap each other.

[0054] Step 4: Place the ribbed steel cage 9 on the ECC block 4;

[0055] Step 5: Attach the second bubble wrap 11 to the lower surface of the top cover plate of the shield tunnel segment steel formwork, and then cover it with the cover plate.

[0056] Step 6: Pour polypropylene fiber ordinary concrete into the steel mold and vibrate it. The exposed part of the upper surface is initially smoothed. Use a rake to roughen the exposed part of the upper surface in both horizontal and vertical directions to form a grid interface 13. Then carry out curing.

[0057] Step 7: After the polypropylene fiber ordinary concrete has initially set, open the cover plate. A second bubble film groove interface 12 is formed at the contact area between the upper surface of the pipe segment and the pipe segment. Arrange the arc-shaped basalt fiber mesh sheet 10 on the upper part and apply UHPC concrete to form the UHPC outer protective layer 3.

[0058] Step 8: Use steam curing method for curing. After complete hardening, the multi-layer composite shield tunnel segment based on fiber concrete is formed.

Claims

1. A multi-layer composite shield tunnel segment based on fiber reinforced concrete, characterized in that, The application relates to a multilayer composite shield tunnel structure. The ECC-NC inner protective layer is located at the lower surface of the whole multilayer composite shield tunnel segment and is composed of ECC blocks and a common concrete grid layer. The common concrete grid layer is composed of horizontal and vertical concrete ribs and covers the lower surface of the multilayer composite shield tunnel segment. The ECC blocks are embedded in the grid positions of the common concrete grid layer and are composed of fiber cement-based composite materials and constructional ribs. The constructional ribs are arranged in a grid shape in the ECC blocks, the two ends of the constructional ribs are provided with upward 90-degree hooks, the hooks extend out of the side surfaces of the ECC blocks, the extending parts of the constructional ribs of adjacent ECC blocks are overlapped, the upper surfaces and the side surfaces of the ECC blocks are first bubble film groove type interfaces, and the joint surfaces between the ECC blocks and the common concrete grid layer are bubble film groove type joint surfaces. The UHPC outer protective layer is made of super high performance concrete material and an arc basalt fiber grid sheet. The joint surface between the UHPC outer protective layer and the segment structure layer is composed of a bubble film groove type joint surface and a grid type interface. The bubble film groove type joint surface is located at the two side regions of the arc length direction of the multilayer composite shield tunnel segment, and the grid type interface is located at the middle region of the arc length direction of the multilayer composite shield tunnel segment. The segment structure layer is made of polypropylene fiber common concrete and a ribbed steel reinforcement cage.

2. The multi-layer composite shield tunnel segment based on fiber reinforced concrete according to claim 1, characterized in that: The groove diameter of the bubble film groove type joint surface is larger than the minimum aggregate particle size of the concrete of the segment structure layer.

3. The multi-layer composite shield tunnel segment based on fiber reinforced concrete according to claim 1, characterized in that: The thickness of the segment structure layer is the thickness calculated according to the stress requirement minus the thickness of the UHPC outer protective layer.

4. The method of manufacturing a multi-layer composite shield tunnel segment based on fiber reinforced concrete according to claim 1, characterized in that, The ECC block is a cuboid structure with a length of 400 mm, a width of 200 mm and a height of 50 mm. The thickness of the UHPC outer protective layer is 50 mm. The application further discloses a manufacturing method of the multilayer composite shield tunnel structure. In step one, an ECC block mold is manufactured, and a first bubble film is pasted in the ECC block mold to form the first bubble film groove type interface on the upper surface and the side surface of the ECC block. In step two, the constructional ribs are reversely arranged so that the end hooks are downward, and fiber cement-based composite materials are poured. After curing and hardening, the mold is removed to form the reversely placed ECC block. In step three, the ECC blocks are uniformly arranged on the whole arc surface of the bottom of the shield tunnel segment steel mold in a distributed manner, and a certain gap is reserved between the ECC blocks to form a concrete grid type structure and increase the bonding performance between the two kinds of concrete. The constructional ribs are overlapped. In step four, the ribbed steel reinforcement cage is placed on the ECC block. In step five, a second bubble film is pasted on the lower surface of the top cover plate of the shield tunnel segment steel mold, and then the cover plate is covered. In step six, polypropylene fiber common concrete is poured into the steel mold and vibrated, and the exposed part of the upper surface is initially smoothed. The exposed part of the upper surface is transversely and longitudinally roughened to form the grid type interface. Then, curing is performed. Step seven: after the initial setting of the polypropylene fiber ordinary concrete, the upper surface of the segment and the contact part of the segment form a second bubble film groove type interface, the arc-shaped basalt fiber grid sheet is arranged on the upper part, and the UHPC concrete is smeared to form a UHPC outer protective layer; Step eight: the steam curing method is used for curing, and after complete hardening, the multilayer composite shield tunnel segment based on the fiber concrete is formed.

5. The method of manufacturing a multi-layer composite shield tunnel segment based on fiber reinforced concrete according to claim 4, characterized in that: In step three, a certain gap of 100mm wide is reserved between the ECC blocks.

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