Portal segment reinforcing structure of main track tunnel

Abstract

A tunnel portal segment reinforcing structure of a main track tunnel comprises tunnel portal segments arranged in a connecting channel tunnel portal area of the main track tunnel, and the multiple tunnel portal segments are spliced through seams. A tunnel portal steel ring section is pre-buried in each tunnel portal segment, and the tunnel portal steel ring sections are spliced and connected to form a complete tunnel portal steel ring; reinforcing steel plates are arranged on the inner side of the tunnel portal segment and outside the range of the tunnel portal steel ring, the reinforcing steel plates are connected with the tunnel portal steel ring sections, and the adjacent reinforcing steel plates are connected. And the tunnel portal duct piece is formed by pouring glass fiber ribs and low-strength concrete within the range of the tunnel portal steel ring. The structure adopts seam splicing and has the advantages of being high in construction efficiency and easy to splice, in addition, the integral rigidity and the bearing capacity of the tunnel portal segment are effectively enhanced through the reinforcing steel plates, structural weakening caused by holing is reduced, meanwhile, the problem that traditional steel bars are difficult to cut is solved through the glass fiber ribs and the low-strength concrete, and the construction cost of the tunnel portal segment is reduced. And the construction efficiency of a mechanical method is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a portal segment reinforcement structure for a mainline tunnel. Background Technology

[0002] In subway tunnel engineering, connecting passages are important structures that connect two main tunnels. Their core function is to provide a safe passage for personnel evacuation and rescue in the event of an emergency such as a fire in one main tunnel, and to effectively prevent the disaster from spreading to adjacent tunnels.

[0003] When constructing connecting passages using mechanical methods such as pipe jacking machines and tunnel boring machines, entrance and exit portals must be pre-installed on the main tunnel segments, and portal steel rings must be installed in the portal areas. Traditional construction methods typically employ staggered segment structures in the portal areas. While this structure offers good overall stability, the assembly process is complex, construction efficiency is low, and localized stress concentrations easily occur at the assembly joints. Furthermore, the portal area itself weakens the overall integrity and rigidity of the segments, making this area a potential weak point in the main tunnel structure and posing a threat to long-term operational safety. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a portal segment reinforcement structure for mainline tunnels. This structure has high construction efficiency, is easy to assemble, and can effectively improve the load-bearing capacity of the portal segments of mainline tunnels.

[0005] To achieve the above objectives, the present invention provides a portal segment reinforcement structure for a mainline tunnel, characterized in that it includes portal segments, which are disposed within the portal area of ​​the connecting passage of the mainline tunnel. Multiple portal segments are provided, and these segments are assembled together with through joints. Each portal segment contains a pre-embedded portal steel ring section, which are then connected to form a complete portal steel ring. Reinforcing steel plates are provided on the inner side of the portal segments and outside the portal steel ring area. These reinforcing steel plates are connected to the portal steel ring sections, and adjacent reinforcing steel plates are also connected. The portal segments within the portal steel ring area are formed by casting glass fiber reinforced concrete.

[0006] As a further improvement of the present invention, the reinforcing steel plate is connected to the portal steel ring section in an L-shape; the reinforcing steel plate is set on the portal segment by studs; the studs are A16 specification with a spacing of 100mm, and two main reinforcement bars are provided inside the portal segment, with the studs set between the two main reinforcement bars.

[0007] As a further improvement of the present invention, the portal segment is formed by casting steel bars and high-strength concrete outside the portal steel ring; the steel bars and the glass fiber reinforcement are fixed by U-shaped clamps; the overlap length of the steel bars and the glass fiber reinforcement is not less than 35D, where D is the diameter of the steel bars or the glass fiber reinforcement.

[0008] As a further improvement of the present invention, the high-strength concrete is C50 high-strength concrete with a permeability grade of P12.

[0009] As a further improvement of the present invention, adjacent portal steel ring sections, adjacent portal steel ring sections and reinforcing steel plates, and reinforcing steel plates are connected by welding, with a weld leg height of not less than 14mm.

[0010] As a further improvement of the present invention, the portal segment is provided in six sections, which are arranged in three rings adjacent to each other along the main tunnel axis. Each ring includes two adjacent portal segments arranged at the top and bottom.

[0011] As a further improvement of the present invention, the low-strength concrete is C40 low-strength concrete with a permeability grade of P12.

[0012] As a further improvement of the present invention, both the door steel ring section and the reinforcing steel plate are made of Q335B steel plate with a thickness of at least 20mm;

[0013] As a further improvement of the present invention, it also includes a connecting passage steel pipe segment disposed in the connecting passage portal area, wherein a sealing steel plate is disposed between the portal steel ring and the connecting passage steel pipe segment.

[0014] As a further improvement of the present invention, the sealing steel plate includes an annular steel plate and a reinforcing angle steel. The annular steel plate is welded between the connecting channel steel pipe segment and the portal steel ring, and the reinforcing angle steel is welded to the annular steel plate and the portal steel ring.

[0015] The beneficial effects of this invention are as follows:

[0016] First, the segments of the tunnel are assembled by continuous joints, which has the advantages of high construction efficiency and simple assembly compared with staggered joint assembly. It also has good adaptability to uneven settlement, relatively uniform stress, and is less likely to cause local stress concentration.

[0017] Second, by pre-embedding portal steel ring sections inside the portal segments and setting reinforcing steel plates on their inner sides, the portal steel ring and reinforcing steel plates form an integral whole. The reinforcing steel plates effectively enhance the overall rigidity and load-bearing capacity of the portal segments and reduce the structural weakening caused by openings.

[0018] Third, the connection between the portal steel ring and the reinforcing steel plate not only improves the structural strength of the portal segments, but also limits the cutting pattern of the portal during mechanical tunneling, prevents over-cutting and the outward expansion of concrete cracks, and ensures construction safety.

[0019] Fourth, the portal segments are constructed using glass fiber reinforced concrete and low-strength concrete within the portal steel ring area, which facilitates direct cutting of this part of the portal segments by the pipe jacking machine or tunnel boring machine, avoiding the problem of difficult traditional steel bar cutting and significantly improving the efficiency of mechanical construction.

[0020] Fifth, the connection between adjacent reinforcing steel plates enhances the rigidity and sealing of the tunnel segment structure, effectively preventing mud or gas leakage from the segment joints during equipment excavation and ensuring stable soil pressure.

[0021] VI. Because the portal segment is equipped with reinforcing steel plates, the steel sleeves used for entering and exiting the tunnel can be more easily welded to the reinforcing steel plates of the portal segment, thus solving the problem of fixing the steel sleeves for equipment entering and exiting the tunnel. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the portal segment reinforcement structure described in this invention;

[0023] Figure 2 This is a schematic diagram of the sealing steel plate structure described in this invention;

[0024] Marking descriptions: 1. Portal segment; 2. Portal steel ring; 21. Portal steel ring section; 3. Reinforcing steel plate; 4. Fiberglass reinforcement; 5. Low-strength concrete; 6. Connecting passage steel segment; 7. Sealing steel plate; 71. Ring steel plate; 72. Reinforcing angle steel. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0026] like Figure 1 As shown, in the portal area of ​​the main tunnel where a connecting passage is required, six special portal segments 1 are installed. These six portal segments 1 are divided into three rings along the tunnel axis, each ring consisting of two portal segments 1, one above the other, and assembled together using a continuous joint assembly method. Compared with the traditional staggered joint assembly, this continuous joint assembly method simplifies the assembly process, improves construction efficiency, and has good adaptability to uneven settlement, resulting in relatively uniform stress and reducing the likelihood of localized stress concentration.

[0027] Each portal segment 1 is prefabricated in the factory with an embedded portal steel ring section 21, which is made of Q335B steel plate with a thickness of at least 20mm. After the six portal segments 1 are assembled in place, the portal steel ring sections 21 are welded together to form a complete, circular portal steel ring 2. This portal steel ring 2 provides precise guidance and strong boundary support for subsequent mechanical tunneling.

[0028] Inside each portal segment 1, outside the portal steel ring 2, a reinforcing steel plate 3 is installed. The reinforcing steel plate 3 is also made of Q335B steel plate with a thickness of at least 20mm. This reinforcing steel plate 3 is welded to the pre-embedded portal steel ring section 21 to form an L-shaped integral structure. The reinforcing steel plate 3 effectively enhances the supporting stiffness of the portal segment 1 after the hole is breached, improving the overall strength and load-bearing capacity of the portal segment 1. It also limits the cutting shape of the portal, prevents over-cutting, and prevents the outward expansion of cracks in the portal-cut concrete. The reinforcing steel plate 3 is fixed to the concrete of the portal segment 1 using A16 standard studs, arranged at 100mm intervals and located between the two main reinforcing bars inside the portal segment 1. This design greatly enhances the bonding force between the reinforcing steel plate 3 and the portal segment 1, preventing them from separating and ensuring the effective transfer of reinforcement.

[0029] The reinforcing steel plates 3 on adjacent portal segments 1 are connected by welding, as are the reinforcing steel plates 3 and adjacent portal steel ring sections 21, with a weld leg height of not less than 14mm. This measure allows the originally independent six segments to form a continuous steel frame in the portal area, significantly improving the overall rigidity and load-bearing capacity of the area and effectively suppressing stress concentration and structural deformation caused by the opening. Simultaneously, the full welding of the joints between the portal steel ring 2 and the reinforcing steel plates 3 not only strengthens the structure but also provides crucial sealing performance: First, for earth pressure balance tunneling machines, air needs to be added to the soil chamber to stabilize the working face; welding seals effectively prevent gas leakage from the segment joints, ensuring stable soil chamber pressure. Second, for slurry balance tunneling machines, slurry pressure needs to be maintained; welding seals also prevent slurry from seeping out of gaps, ensuring the balance of water and soil pressure at the working face, thereby improving the safety and controllability of the construction process.

[0030] Within the area enclosed by the portal steel ring 2 and about to be cut by the tunnel jacking machine or shield machine, the portal segment 1 uses glass fiber reinforced concrete 4 instead of ordinary steel bars, and is poured with C40 low-strength concrete 5 with a permeability grade of P12. The glass fiber reinforced concrete 4 has high tensile strength but can be easily cut by the tunneling machine cutterhead, and the C40 low-strength concrete 5 is also easier to break. This fundamentally solves the problems of difficult, time-consuming, and severely wear-prone traditional reinforced concrete portal tunneling, greatly improving the efficiency and safety of mechanical construction.

[0031] In the non-cutting area outside the portal steel ring 2, the portal segment 1 is poured with C40 low-strength concrete of impermeability grade P12 to ensure the strength of the main tunnel structure. The reinforcing bars and glass fiber reinforced bars 4 are lapped and fixed together using U-shaped clamps, with an overlap length of not less than 35D, where D is the diameter of the reinforcing bar or glass fiber reinforced bar 4. This connection method ensures effective stress transfer between the two different material areas, guaranteeing the continuity and reliability of the structure's stress distribution.

[0032] After the connecting tunnel is completed, a permanent portal ring beam structure needs to be constructed at the connection point between the main tunnel and the connecting tunnel. To seal the construction gap between the main tunnel segments and the connecting tunnel segments, a sealing steel plate structure 7 was installed.

[0033] like Figure 2 As shown, specifically, a sealing steel plate 7 is installed between the portal steel ring 2 and the connecting passage steel segment 6. The sealing steel plate 7 consists of a 10mm thick annular steel plate 71 and several 10mm thick reinforcing angle steels 72. The annular steel plate 71 is welded between the connecting passage steel segment 6 and the portal steel ring 2, and the reinforcing angle steels 72 are welded to the annular steel plate 71 and the portal steel ring 2 at intervals of 30°. The sealing steel plate 7 greatly enhances the sealing performance at the connection between the connecting passage and the main tunnel, eliminating the risk of leakage during operation.

[0034] The above-described embodiments are merely illustrative of the present invention. Any equivalent embodiments made by those skilled in the art, without departing from the scope of the technical features disclosed in the present invention, using partial modifications or alterations to the technical content disclosed in the present invention, shall still fall within the scope of the technical features of the present invention.

Claims

1. A portal segment reinforcement structure for a mainline tunnel, characterized in that: The system includes portal segments, which are installed in the portal area of ​​the connecting passage of the main tunnel. Multiple portal segments are installed and assembled together with continuous joints. Each portal segment contains a pre-embedded portal steel ring section, which are then connected to form a complete portal steel ring. Reinforcing steel plates are installed on the inner side of each portal segment, outside the portal steel ring area. These reinforcing steel plates are connected to the portal steel ring sections, and adjacent reinforcing steel plates are also connected. The portal segments within the portal steel ring area are formed using glass fiber reinforcement and low-strength concrete.

2. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: The reinforcing steel plate is connected to the portal steel ring section in an L-shape; the reinforcing steel plate is set on the portal segment by studs; the studs are A16 specification with a spacing of 100mm; the portal segment is provided with two main reinforcement bars, and the studs are set between the two main reinforcement bars.

3. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: The portal segment is formed by casting steel bars and high-strength concrete outside the portal steel ring; the steel bars and the glass fiber reinforcement are fixed by U-shaped clamps; the overlap length of the steel bars and the glass fiber reinforcement is not less than 35D, where D is the diameter of the steel bars or the glass fiber reinforcement.

4. The portal segment reinforcement structure for a mainline tunnel according to claim 3, characterized in that: The high-strength concrete is C50 high-strength concrete with a permeability grade of P12.

5. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: Adjacent portal steel ring sections are connected by welding, as are adjacent portal steel ring sections and reinforcing steel plates, and reinforcing steel plates, with a weld leg height of not less than 14mm.

6. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: The portal segment consists of six sections, arranged in three rings along the main tunnel axis, with each ring including two adjacent portal segments arranged at the top and bottom.

7. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: The low-strength concrete is C40 low-strength concrete with a permeability grade of P12.

8. The portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: Both the door steel ring section and the reinforcing steel plate are made of Q335B steel plate with a thickness of at least 20mm.

9. A portal segment reinforcement structure for a mainline tunnel according to claim 1, characterized in that: It also includes connecting passage steel pipe segments installed in the connecting passage portal area, with a sealing steel plate installed between the portal steel ring and the connecting passage steel pipe segments.

10. A portal segment reinforcement structure for a mainline tunnel according to claim 9, characterized in that: The sealing steel plate includes an annular steel plate and reinforcing angle steel. The annular steel plate is welded between the connecting channel steel pipe segment and the portal steel ring, and the reinforcing angle steel is welded to the annular steel plate and the portal steel ring.

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