Protective structure and construction method for early construction of subway tunnels in transportation hubs

Abstract

A protective structure and construction method for subway tunnels constructed in advance within a transportation hub meet the requirements for later hub construction and effectively protect the pre-constructed subway tunnel, significantly reducing construction time and project investment. The structure comprises the hub's underground structure and a subway tunnel anti-floating protection structure. The subway tunnel, constructed in advance and operational using a shield tunneling method, is separated from the hub's underground structure. The subway tunnel's anti-floating protection structure includes pullout piles and anti-floating beams, with the pullout piles spaced along the line on both sides of the subway tunnel. The anti-floating beams are located above the subway tunnel and spaced along the line, with each anti-floating beam forming a fixed connection with the pullout piles beneath it. The hub's underground structure comprises a hub cap, cap pile foundations, and a hub center column, with the cap pile foundations spaced along the line on both sides of the subway tunnel. The hub cap is located above the subway tunnel, closely attached to the anti-floating beams beneath it and consolidated with the cap pile foundation tops. The hub center column rests on the cap.

Description

Technical Field

[0001] The present invention relates to a transportation hub and subway combined construction project, and in particular to a protective structure and a construction method for the early construction of a subway tunnel in a transportation hub. Background Art

[0002] Multiple subway lines are often designed in urban integrated transportation hubs. When a subway line passes through an integrated transportation hub, the subway tunnel is generally laid under the bottom slab of the transportation hub. Due to the large load demand of the transportation hub column network, a large number of pedestal pile foundations often need to be set up underground. The subway tunnel and the pedestal pile foundation will inevitably conflict in space and are difficult to avoid. The usual practice is to build the subway tunnel together with the transportation hub column network pedestal above. At present, the combined construction method of the subway tunnel and the transportation hub pedestal pile foundation is mainly based on the large-scale excavation and then structural construction. The subway tunnel is required to use the open-cut method to envelop the hub pedestal, and the hub pedestal is located under the subway tunnel structure and built together with the subway tunnel structure. However, the adoption of the combined structural construction method requires, on the one hand, that the construction periods of the subway and the transportation hub be matched, and that the hub station building plan reach a certain depth. However, since there are multiple subway lines planned in the transportation hub, which is large in scale and has a long construction period, it is usually difficult to match the subway construction period. If the open-cut combined construction method of the subway tunnel and the hub pedestal structure is still adopted, it will inevitably affect the progress of the subway construction. On the other hand, the open-cut method for the subway tunnel and the method of enveloping the hub pedestal requires a significant increase in investment compared to the shield tunnel.

[0003] If the subway construction period does not match the planned hub construction period, the subway opening time will be delayed, which will cause huge economic losses. Therefore, when the transportation hub construction period does not match the subway, it is necessary to study a method to implement and open the subway tunnel first and then implement the transportation hub.

[0004] That is, the protective structure and construction method of a subway tunnel in the early construction of a transportation hub studied in this invention can not only ensure the progress of subway construction and meet the conditions for later hub construction, but also take effective protection measures for the early implementation of subway tunnels. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a protective structure for subway tunnels constructed in advance in transportation hubs, so as to ensure the progress of subway construction and meet the conditions for later hub construction. It can also take effective protection measures for subway tunnels implemented in advance, greatly saving construction time and project investment.

[0006] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0007] The present invention provides a protective structure for a subway tunnel constructed in advance in a transportation hub, and is characterized in that it includes a hub underground structure and a subway tunnel anti-floating protective structure, wherein the subway tunnel constructed in advance and put into operation using a shield method is separated from the hub underground structure; the subway tunnel anti-floating protective structure includes pull-out piles and anti-floating beams, and the pull-out piles are arranged at intervals on both sides of the subway tunnel along the line direction; the anti-floating beams are located above the subway tunnel, arranged at intervals along the line direction, and are perpendicular to the subway tunnel line direction in their length directions, and each anti-floating beam is fixedly connected to the pull-out piles below it; the hub underground structure includes a hub cap, a cap pile foundation, and a hub center column, and the cap pile foundations are arranged at intervals on both sides of the subway tunnel along the line direction; the hub cap is arranged above the subway tunnel, closely adheres to each anti-floating beam below it and is consolidated with the top of the cap pile foundation, and the hub center column is located on the hub cap.

[0008] Another technical problem to be solved by the present invention is to provide a construction method for the protective structure of the above-mentioned subway tunnel constructed in advance in a transportation hub, the construction method comprising the following steps:

[0009] ① Use the shield method to construct the subway tunnel in advance and put it into operation;

[0010] ②Construct the hub cap pile foundation and anti-pull piles from the ground. The anti-pull piles are drilled with full casing and prestressed steel bars are embedded on the top;

[0011] ③ Preliminary excavation of the soil above the existing subway tunnel from the surface until the thickness of the covering soil is 1.5 times the diameter of the subway tunnel;

[0012] ④ Prefabricated anti-floating beams, with corrugated pipes embedded at the ends of the anti-floating beams for the prestressed steel bars to pass through;

[0013] ⑤ Divide the excavation width of the remaining soil along the longitudinal direction of the subway tunnel. The excavation width of each section is limited to the construction of one set of anti-floating structural units, and the excavation elevation is the bottom surface of the anti-floating beam;

[0014] ⑥ Excavate the first section of soil, install the first anti-floating beam, set a circle of rubber pads on the top of the anti-pullout pile, apply prestressing force through prestressed steel bars, lock it with anchors after prestressing, and fill the gaps with grouting;

[0015] ⑦ Excavate the second section of soil and install the second anti-floating beam. The net distance between adjacent anti-floating beams should be less than the ring width of the subway tunnel shield segment.

[0016] ⑧ Repeat the above steps ⑥ and ⑦ to construct the remaining anti-floating beams in sequence;

[0017] ⑨After the construction of each anti-floating beam is completed, the remaining soil is excavated and the hub foundation is constructed;

[0018] ⑩Construct hub center column, hub bottom plate and other hub structures.

[0019] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0020] The subway tunnel is separated from the underground structure of the hub (hub pedestal and pedestal pile foundation). The subway tunnel is constructed in advance and put into operation using the shield method. The hub pedestal is set above the subway tunnel, and the pedestal pile foundations are set on both sides of the subway tunnel. During the pedestal excavation, a protective structure is set for the subway tunnel to prevent the subway tunnel from floating or rebounding and deforming. This ensures the progress of subway construction while meeting the conditions for the later implementation of the hub, which can greatly save construction time and project investment.

[0021] Anti-floating beams are used to provide active prestressing, which plays a locking role on the subway tunnel after local soil excavation. This can effectively prevent the subway tunnel from floating or rebound deformation, and provides an effective solution to similar floating deformation problems in existing subway tunnels.

[0022] 3. The structural stress is clear and the economic benefits are significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] This specification includes the following six drawings:

[0024] Figure 1 This is a schematic plan view of the protective structure of the subway tunnel constructed in advance in a transportation hub according to the present invention;

[0025] Figure 2 This is a schematic diagram of the subway tunnel and the pile foundation after the construction of the protective structure of the subway tunnel constructed in advance in the transportation hub according to the present invention is completed;

[0026] Figure 3 This is a schematic diagram of the present invention after the subway tunnel is excavated to the bottom of the anti-floating beam in the protective structure constructed in advance in the transportation hub and the anti-floating beam is installed;

[0027] Figure 4 This is a schematic diagram of the hub cap column network in the protective structure of the subway tunnel constructed in advance in the transportation hub of the present invention after the construction is completed;

[0028] Figure 5 It is along Figure 3 Sectional view along line AA;

[0029] Figure 6 yes Figure 4 A partial enlarged view of middle B.

[0030] The figure shows the main components and their corresponding markings: subway tunnel 10, hub cap pile foundation 20, pull-out piles 21, prestressed steel bars 22, rubber washers 23, anti-floating beams 30, corrugated pipes 31, anchors 32, grouting gaps 33, hub cap 40, hub center column 50, hub bottom plate 60, clear distance C between adjacent anti-floating beams, length L of prestressed steel bars anchored in pull-out piles, length d of prestressed steel bars anchored in hub cap, and the first to ninth soil sections L1 to L9. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples.

[0032] Reference Figure 1 The protective structure of the subway tunnel constructed in advance in the transportation hub of the present invention includes the hub underground structure and the subway tunnel anti-floating protection structure. The subway tunnel 10, which was constructed and put into operation in advance using the shield method, is separated from the hub underground structure. The subway tunnel anti-floating protection structure includes anti-pullout piles 21 and anti-floating beams 30. The anti-pullout piles 21 are arranged at intervals on both sides of the subway tunnel 10 along the line direction. The anti-floating beams 30 are located above the subway tunnel 10 and are arranged at intervals along the line direction. The length direction is perpendicular to the line direction of the subway tunnel 10. Each anti-floating beam 30 is fixedly connected to the anti-pullout pile 21 below it. The hub underground structure includes a hub cap 40, a cap pile foundation 20, and a hub center column 50. The cap pile foundation 20 is arranged at intervals on both sides of the subway tunnel 10 along the line direction. The hub cap 40 is located above the subway tunnel 10 and is closely attached to each anti-floating beam 30 below it and is fixed to the top of the cap pile foundation 20. The hub center column 50 is located on the hub cap 40.

[0033] Reference Figure 1 and Figure 4 In the present invention, the subway tunnel 10 is separated from the underground structure of the hub. The subway tunnel 10 is constructed and put into operation in advance using the shield method. The hub cap 40 is set above the subway tunnel 10, and the cap pile foundation 20 is set on both sides of the subway tunnel 10. During the excavation of the hub cap 40, a protective structure is set for the subway tunnel 10. While ensuring the progress of subway construction, it also meets the conditions for the later implementation of the hub, which can greatly save construction time and project investment.

[0034] Reference Figure 1 、 Figure 4 and Figure 6The pull-out pile 21 is drilled using a full casing, and prestressed steel bars 22 are embedded in the top. The prestressed steel bars 22 pass upward through the anti-floating beam 30 and are anchored to the hub cap 40 for a certain length. A gap 33 is left between the top surface of the pull-out pile 21 and the bottom surface of the anti-floating beam 30. A circle of rubber pads 23 are installed along the top surface of the pile. The compression of the rubber pads 23 provides prestress for the anti-floating beam. After the prestress is applied, the gap 33 is filled by grouting. The anti-floating beam 30 is a prefabricated beam with a corrugated tube 31 embedded at the end. The prestressed steel bars 22 pass through the corrugated tube 31 and are locked by the anchor 32 after the prestress is applied. In other words, the anti-floating beam 30 provides active prestress, which locks the subway tunnel 10 after local soil excavation, effectively preventing the subway tunnel 10 from floating or rebounding. This provides an effective solution to similar floating deformation problems in existing subway tunnels.

[0035] Reference Figures 1 to 6 The method for constructing a protective structure for a subway tunnel in a transportation hub in advance according to the present invention comprises the following steps:

[0036] ① Use the shield method to construct subway tunnel 10 in advance and put it into operation;

[0037] ② Construct the hub cap pile foundation 20 and anti-pull pile 21 from the ground. The anti-pull pile 21 is drilled with a full casing and prestressed steel bars 22 are embedded on the top.

[0038] ③ Preliminary excavation of the soil above the existing subway tunnel 10 from the surface until the soil cover thickness reaches 1.5 times the diameter of the subway tunnel;

[0039] ④ Prefabricated anti-floating beam 30, the end of the anti-floating beam is pre-embedded with a corrugated pipe 31 for the prestressed steel bar 22 to pass through;

[0040] ⑤ Divide the excavation width of the remaining soil along the direction of subway tunnel 10. The excavation width of each section is limited to the construction of one set of anti-floating structural units. The excavation elevation is the bottom surface of the anti-floating beam 30;

[0041] ⑥ Excavate the first section of soil L1, install the first anti-floating beam 30, set a circle of rubber pads 23 on the top of the anti-pull pile 21, apply prestressing force through the prestressed steel bars 22, lock it with anchors 32 after prestressing, and fill the gap 33 with grouting;

[0042] ⑦ Excavate the second soil section L2 and install the second anti-floating beam 30. The clearance C between adjacent anti-floating beams is less than the ring width of the subway tunnel 10 shield segments.

[0043] ⑧ Repeat the above steps ⑥ and ⑦ to construct the remaining anti-floating beams 30 in sequence;

[0044] ⑨ After the construction of each anti-floating beam 30 is completed, the remaining soil is excavated and the hub foundation 40 is constructed;

[0045] ⑩Construct the hub center column 50, hub bottom plate 60 and other hub structures. Example

[0046] A section of the Shenzhen Metro passes through a comprehensive transportation hub. According to the plans and construction plans of both parties, the construction period of the hub is two years later than that of the subway. If the hub pier is set under the subway tunnel according to the conventional design and the open-cut and synchronous construction method is adopted, the subway tunnel and other hub pier pile foundation schemes must be fully stabilized before they can be constructed simultaneously, which will greatly affect the progress of subway construction. In order to ensure the opening of the subway and meet the conditions for the later hub construction, the construction unit adopted the protective structure and construction method of the subway tunnel in the transportation hub constructed in advance of the present invention. That is, the subway tunnel is constructed in advance using the shield method and opened to traffic as planned. The hub pier is set above the subway tunnel. During the later construction of the hub pier, prestressed anti-floating beams are set as the subway protection structure to resist the floating or rebound deformation of the subway tunnel, ensuring the safety of subway operation. Compared with the open-cut and synchronous construction scheme, it has great social and economic benefits.

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Ordinary technicians in this field can make various similar expressions under the guidance of the present invention without violating the purpose and claims of the present invention. Such changes fall within the scope of protection of the present invention.

Claims

1. The protective structure of the subway tunnel constructed in advance in the transportation hub is characterized by: The invention comprises a hub underground structure and a subway tunnel anti-floating protection structure, wherein the subway tunnel (10) which is constructed and put into operation in advance by using a shield method is separated from the hub underground structure; the subway tunnel anti-floating protection structure comprises anti-pullout piles (21) and anti-floating beams (30), wherein the anti-pullout piles (21) are arranged at intervals along the line direction on both sides of the subway tunnel (10); the anti-floating beams (30) are located above the subway tunnel (10), are arranged at intervals along the line direction, and are perpendicular to the line direction of the subway tunnel (10) in the length direction. Each anti-floating beam (30) is fixedly connected to the anti-pull pile (21) below it; the hub underground structure includes a hub cap (40), a cap pile foundation (20) and a hub center column (50); the cap pile foundation (20) is arranged at intervals on both sides of the subway tunnel (10) along the line direction; the hub cap (40) is arranged above the subway tunnel (10), and is closely attached to each anti-floating beam (30) below it and is consolidated with the top of the cap pile foundation (20); the hub center column (50) is located on the hub cap (40).

2. The protective structure for the early construction of a subway tunnel in a transportation hub as claimed in claim 1, characterized in that: The pull-out pile (21) is drilled with a full casing, and prestressed steel bars (22) are embedded in the top. The prestressed steel bars (22) pass through the anti-floating beam (30) upward and are anchored in the hub cap (40) for a certain length. A gap (33) is left between the top surface of the pull-out pile (21) and the bottom surface of the anti-floating beam (30), and a circle of rubber pads (23) are set along the top surface of the pile. Prestress is provided to the anti-floating beam through compression of the rubber pads (23). After the prestress is applied, the gap (33) is filled by grouting.

3. The protective structure for the early construction of a subway tunnel in a transportation hub as claimed in claim 2, characterized in that: The anti-floating beam (30) is a prefabricated beam, and a corrugated pipe (31) is pre-buried at the end. The prestressed steel bars (22) pass through the corrugated pipe (31) and are locked by the anchor (32) after prestress is applied.

4. The method for constructing a protective structure for a subway tunnel in a transportation hub in advance as claimed in claim 3 comprises the following steps: ① Use shield method to construct subway tunnel (10) in advance and put it into operation; ② Construct the hub cap pile foundation (20) and the pull-out pile (21) from the ground. The pull-out pile (21) is drilled with a full casing and prestressed steel bars (22) are embedded in the top. ③ Preliminary excavation of the soil above the existing subway tunnel (10) from the surface until the soil thickness reaches 1.5 times the diameter of the subway tunnel; ④ Prefabricated anti-floating beams (30), with corrugated pipes (31) embedded in the ends of the anti-floating beams for the prestressed steel bars (22) to pass through; ⑤ Divide the excavation width of the remaining soil along the direction of the subway tunnel (10), and the excavation width of each section is limited to the construction of one group of anti-floating structural units, and the excavation elevation is the bottom surface of the anti-floating beam (30); ⑥ Excavate the first section of soil (L1), install and construct the first anti-floating beam (30), set a circle of rubber pads (23) on the top of the anti-pull pile (21), apply prestress through the prestressed steel bars (22), lock it with anchors (32) after the prestress is applied, and fill the gap (33) with grouting; ⑦ Excavate the second section of soil (L2), install and construct the second anti-floating beam (30), and the net distance (C) between adjacent anti-floating beams is less than the ring width of the shield segment of the subway tunnel (10); ⑧ Repeat the above steps ⑥ and ⑦ to construct the remaining anti-floating beams (30) in sequence; ⑨ After the construction of each anti-floating beam (30) is completed, the remaining soil is excavated and the hub foundation (40) is constructed; ⑩Construct the hub center column (50), hub bottom plate (60) and other hub structures.

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