Tunnel and station integrated structure suitable for soft soil stratum and construction method

Abstract

The invention relates to the technical field of rail transit construction, in particular to a tunnel and station integrated structure suitable for a soft soil stratum and a construction method, and the structure comprises a large-diameter station tunnel, a small-diameter interval tunnel and a vertical traffic core; the vertical traffic core is arranged in the middle of the station, the large-diameter station tunnels are connected to the two sides of the vertical traffic core, and the small-diameter interval tunnel is connected with the large-diameter station tunnels through the connection section. A subway track area arranged on one side in an offset mode and a station platform located on the side of the subway track area are arranged in the large-diameter station tunnel. A subway track area is arranged in the middle of the small-diameter interval tunnel; and the connecting section is arranged at the tail end of the large-diameter station tunnel. The structure combining the intensive vertical traffic core and the variable-diameter tunnel is adopted, and compared with a traditional open cut station, the demolition range and the construction occupied space are remarkably reduced; compared with a traditional underground excavation station, the construction safety and reliability of a soft soil area are improved, and the construction risk of a deep foundation pit and the disturbance risk to the surrounding environment are reduced.

Description

Technical Field

[0001] This invention relates to the field of rail transit construction technology, and in particular to an integrated tunnel and station structure and construction method suitable for soft soil strata. Background Technology

[0002] With the exponential growth in urban travel demand, urban subway networks are becoming increasingly dense, and the environmental conditions for constructing subway stations are becoming more and more stringent and complex. In particular, subway stations in bustling urban areas face challenges such as dense residential communities, important cultural heritage buildings, narrow and busy roads, and crisscrossing pipelines, making the design and construction of subway stations face the challenges of being "unable to demolish," "unsuitable for placement," and "untouchable." In addition, residents are becoming increasingly sensitive to and demanding in terms of travel environment and noise pollution. The traditional large-scale open-cut construction method for subway stations has problems such as large-scale demolition, serious traffic disruption, long-term disturbance to residents, and difficulties in construction organization. On the other hand, the traditional tunneling method is not suitable for soft soil areas due to high safety risks and high construction costs.

[0003] Therefore, it is necessary to provide an integrated tunnel and station structure and construction method suitable for soft soil strata to solve the above-mentioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated tunnel and station structure and construction method suitable for soft soil strata. The specific technical solution is as follows: An integrated tunnel and station structure suitable for soft soil strata includes a large-diameter station tunnel, a small-diameter section tunnel, and a vertical transportation core; The vertical transportation core is located in the middle of the station, the large-diameter station tunnel connects the two sides of the vertical transportation core, and the small-diameter section tunnel is connected to the large-diameter station tunnel through a connecting section; The large-diameter station tunnel has a subway track area offset to one side and a station platform located next to the subway track area; the small-diameter section tunnel has a subway track area located in the center. The connecting section is located at the end of the large-diameter station tunnel and is used to eccentrically connect the large-diameter station tunnel with the small-diameter section tunnel.

[0005] Furthermore, the vertical transportation core is a multi-layered structure combining underground and above-ground components, including underground subway equipment rooms, station transfer passages, and platform levels, as well as above-ground station halls, entrances and exits connecting to the ground, and commercial development spaces. It also includes a vertical elevator shaft connecting the above-ground and underground components, which is connected to the subway equipment rooms, station halls, station transfer passages, and platform levels.

[0006] Furthermore, the large-diameter station tunnel is also equipped with a pipe gallery and a ventilation and smoke exhaust structure.

[0007] A construction method for an integrated tunnel and station structure suitable for soft soil strata, as described above, includes the following steps: S1. At the center of the station's designed location, construction will form a vertical traffic core; S2. Using the vertical traffic core as the starting working shaft, start excavating large-diameter station tunnels on both sides of the line; S3. After the large-diameter station tunnel has been excavated to the preset length, the soil inside the tunnel is reinforced at the tunnel face. S4. Perform diameter-changing construction work inside the reinforced tunnel and complete the excavation of the small-diameter section tunnel.

[0008] Furthermore, in S1, the construction of the vertical transportation core adopts a mechanical shaft construction process, specifically including: S11. Reinforce the ground foundation and pour a ring foundation on the outside of the wellhead; S12, Construction cutting edge and initial well body; S13. In-well hoisting main unit, equipped with telescopic boom and excavation tools; S14. The cutterhead cuts the soil and performs vertical tunneling with water. The outer wall of the vertical traffic core structure sinks synchronously with the excavation, and the inclinometer monitors and corrects the deviation. S15. After excavating to the bottom of the pit, pour concrete to seal the bottom; and construct the internal structure of the vertical transportation core.

[0009] As a preferred technical solution, the variable diameter top shield construction method is adopted for construction, specifically: In S2, a variable-diameter shield tunneling machine was used to construct the large-diameter station tunnel using the pipe jacking method. In S4, the variable diameter top shield machine is converted into a small diameter shield machine, and the shield tunneling method is used to construct the small diameter section tunnel.

[0010] Furthermore, the large-diameter station tunnel was constructed using a variable-diameter shield tunneling machine via pipe jacking, specifically: S2.1 Install a temporary pipe jacking backrest reaction frame, pipe jacking machine jacking cylinder, and assemble a variable diameter shield machine and pipe jacking sections within the vertical transportation core; S2.2, Install one section of shield tunneling steel segment, one top shield conversion ring, and one section of jacking steel segment in the top shield machine; S2.3 After installation, use a large-diameter jacking pipe to start jacking.

[0011] Furthermore, S4 includes: S41. Within the diameter variation range at the end of the large-diameter station tunnel, perform grouting reinforcement or freezing reinforcement inside the tunnel face. S42. Remove the connecting parts between the large and small cutterheads in the variable diameter shield machine and the connecting parts between the shield body of the large diameter pipe jacking machine and the small diameter shield machine. S43. Install the conversion ring and subsequent supporting mechanism for the starting of the small-diameter shield machine to complete the diameter conversion of the top shield machine; S44. Use the small-diameter shield machine to start excavation and carry out small-diameter section tunnel construction.

[0012] As a preferred technical solution, the mother-and-child shield tunneling method is used for construction. Specifically: In S2, a mother-and-child shield tunneling machine was used to construct the large-diameter station tunnel. In S4, the large-diameter shield body and the small-diameter shield body of the mother and son shield tunneling machines are separated inside the tunnel, and a conversion ring is installed to convert it into a small-diameter shield tunneling machine to continue tunneling and complete the construction of the small-diameter section tunnel.

[0013] Furthermore, the diameter-changing construction operation is an eccentric diameter-changing operation, which makes the center line of the small-diameter section tunnel after the conversion not concentric with the center line of the large-diameter station tunnel, thus realizing the connection between the subway track area of ​​the large-diameter station tunnel and the subway track area of ​​the small-diameter section tunnel.

[0014] The application of the technical solution of the present invention has at least the following beneficial effects: (1) The present invention provides an integrated tunnel and station structure suitable for soft soil strata, including a large-diameter station tunnel, a small-diameter section tunnel and a vertical transportation core; the vertical transportation core is located in the middle of the station, the large-diameter station tunnel is connected to both sides of the vertical transportation core, and the small-diameter section tunnel is connected to the large-diameter station tunnel through a connecting section; the large-diameter station tunnel is provided with a subway track area offset to one side and a station platform located next to the subway track area; the small-diameter section tunnel is provided with a subway track area in the center; the connecting section is located at the end of the large-diameter station tunnel and is used to eccentrically connect the large-diameter station tunnel and the small-diameter section tunnel. This invention employs a structure combining an intensive vertical transportation core with a variable-diameter tunnel. Compared to traditional open-cut stations, it fundamentally avoids the need for large-scale open-cut operations in traditional subway station construction. This significantly reduces the demolition area and construction land occupation, minimizing traffic diversion pressure and pipeline relocation work caused by open-cut construction. Compared to traditional tunnel-cut stations, it improves the safety and reliability of construction in soft soil areas, reduces the risks of deep foundation pits and large-section tunnel construction, and minimizes the risk of disturbance to surrounding sensitive buildings and underground pipelines.

[0015] (2) In this invention, the vertical transportation core integrates functions such as the starting working shaft, platform level, ventilation shaft, equipment room, vertical lifting elevator shaft, station hall, entrance and exit and commercial development space. Through structural integration, the scale of open excavation of the station is greatly reduced, and the impact of open excavation on demolition, traffic and environment is reduced from the source. At the same time, the above-ground part of the vertical transportation core can be flexibly combined with the development needs of the surrounding plots, and the entrances and exits are connected with commercial facilities, transportation hubs and other facilities to improve the commercial operation efficiency and comprehensive service value of rail transit.

[0016] (3) In this invention, the large-diameter station tunnel and the small-diameter section tunnel are eccentrically connected through a connecting section, so that the offset large-diameter station tunnel subway track area can smoothly transition to the central small-diameter section tunnel subway track area, thereby shortening the length of the connecting section, optimizing the line and reducing the project cost.

[0017] (4) This invention provides a construction method for an integrated tunnel and station structure suitable for soft soil strata. Compared with the traditional cut-and-cover method, the top shield mechanical construction technology adopted in this invention has significant advantages in the construction of subway stations in soft soil areas. Through the in-tunnel variable diameter mechanical construction technology, the settlement and deformation of soft soil strata can be precisely controlled, reducing the inherent construction risks and safety hazards to the surrounding environment of the traditional cut-and-cover method from the source. In addition, the vertical transportation core integrates core functions such as the station hall, platform level, equipment room and vertical lifting passage (vertical lifting elevator shaft), without the need for additional cut-and-cover construction of the station hall and inclined connecting passage, completely avoiding the construction risks of cut-and-cover operations in soft soil strata; the vertical transportation core can be constructed using mechanical shaft construction technology, which can reduce the inherent deep foundation pit construction risks and reduce the safety hazards of surrounding sensitive buildings compared with the traditional open-cut shaft.

[0018] (5) In this invention, the construction scheme of the variable diameter jacking shield machine (variable diameter pipe jacking machine + shield machine combination) is adopted. Compared with the shield station construction, by using the large diameter pipe jacking construction station, the requirement of the supporting equipment after the shield construction is launched separately can be avoided, which significantly reduces the ground construction area and operation scale. At the same time, the completed pipe jacking tunnel can be used as the supporting site for the small diameter shield machine, without the need to occupy additional ground space. The impact of construction on demolition, traffic and environment can be further reduced through the recycling of space. In addition, when the variable diameter jacking shield machine changes diameter, the conversion segment and other limit devices can be pre-installed in the working shaft in advance, which simplifies the diameter change process in the tunnel and reduces the construction risk.

[0019] (6) In this invention, the eccentric variable diameter tunnel construction method is adopted. The problem of the vehicle track area centerline not coinciding with the tunnel centerline is solved by the eccentric variable diameter (non-concentric) of the large and small shield equipment. The vehicle track areas of the large and small tunnels are connected, the length of the connection section of the large-diameter station tunnel is shortened, the line length is shortened, the project scale is reduced, and the cost is saved.

[0020] (7) In this invention, compared with the traditional open-cut + cut-and-cover combined construction, the tunnel and station integrated construction method based on variable diameter top shield adopts mechanical construction, effectively reduces the cut-and-cover work conditions of various structures, greatly simplifies the construction process, not only significantly shortens the overall construction period, but also reduces the cost input caused by multiple process cross-operations and complex work conditions, and achieves a dual improvement in project construction efficiency and economy.

[0021] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the planar structure of the integrated tunnel and station structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-section of a large-diameter station tunnel; Figure 3 This is a schematic diagram of the cross-section of a small-diameter tunnel. Figure 4 This is the station transfer level layout plan; Figure 5 This is the longitudinal section layout diagram of the station; Figure 6 This is the cross-sectional layout diagram of the station; Figure 7 This is a schematic diagram of the cross-section of the eccentric variable diameter section; Figure 8 This is a schematic diagram of an eccentrically variable diameter plane. The following are the diagram labels: 1. Large-diameter station tunnel; 2. Small-diameter section tunnel; 3. Metro track area; 4. Station platform; 5. Vertical transportation core; 5.1. Metro equipment room; 5.2. Vertical elevator shaft; 5.3. Station concourse; 5.4. Entrance / exit; 5.5. Commercial development space; 5.6. Station transfer passage; 5.7. Platform level; 6. Section utility tunnel; 7. Ventilation and smoke exhaust structure; A represents the centerline of the metro track area of ​​the large-diameter station tunnel; B represents the centerline of the metro track area of ​​the small-diameter section tunnel. Detailed Implementation

[0023] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] Example 1: See Figures 1 to 6 This invention proposes an integrated tunnel and station structure suitable for soft soil strata, comprising a large-diameter station tunnel 1, a small-diameter section tunnel 2, and a vertical transportation core 5; the vertical transportation core 5 is located in the middle of the station, and the large-diameter station tunnel 1 connects to both sides of the vertical transportation core 5 (e.g., Figure 1 As shown in the figure, the small-diameter section tunnel 2 is connected to the large-diameter station tunnel 1 through a connecting section; See Figure 2 The large-diameter station tunnel 1 contains a subway track area 3 offset to one side and a station platform 4 located beside the subway track area 3; see also Figure 3 The small-diameter section tunnel 2 contains a centrally located metro track area 3. Metro vehicles need to transition from one side of the station tunnel to the center of the section tunnel. This transition can be achieved in two ways: ① Extend the length of the large-diameter station tunnel and install a transition section within it, shifting the metro line from one side to the center of the section tunnel. ② Employ eccentric diameter-changing technology, connecting the large-diameter station tunnel 1 and the small-diameter section tunnel 2 eccentrically (e.g., ...). Figure 7 and Figure 8 This shortens the length of the connection section between the large-diameter station tunnel and the small-diameter section tunnel.

[0027] In this embodiment, the second method is preferred. Specifically, the connecting section is set at the end of the large-diameter station tunnel. By using the eccentric diameter-changing construction method in the connecting section, the large-diameter station tunnel and the small-diameter section tunnel are eccentrically connected, thereby realizing the transition from the offset subway track area in the large-diameter station tunnel to the centrally located subway track area in the small-diameter section tunnel.

[0028] See Figure 1 as well as Figures 4-6 The vertical transportation core 5 is a multi-layered structure combining underground and above-ground components. It includes underground subway equipment rooms 5.1, station transfer passages 5.6, and platform levels 5.7, as well as above-ground station halls 5.3, entrances / exits 5.4 connecting to the ground, and commercial development space 5.5. It also includes a vertical elevator shaft 5.2 connecting the above-ground and underground components. The vertical elevator shaft 5.2 is connected to the subway equipment rooms 5.1, station halls 5.3, station transfer passages 5.6, and platform levels 5.7, thus meeting the various functional requirements of the subway station.

[0029] In this embodiment, the large-diameter station tunnel 1 is also equipped with a section pipe gallery 6 and a ventilation and smoke exhaust structure 7, such as Figure 2 As shown, the tunnel 6 and ventilation and smoke exhaust structure 7 are located corresponding to the station platform 4, meeting the station's functions and passenger travel needs. The vertical transportation core 5 is also equipped with an exhaust shaft, and the ventilation and smoke exhaust structure 7 is connected to the exhaust shaft.

[0030] In this invention, at complex stations with challenging ground environments and limited space, only a small construction area is needed. A vertical transportation core is set up in the center of the station. This core highly integrates functions such as the starting work shaft, platform level, ventilation shaft, equipment rooms, vertical lifting channels (vertical lifting elevator shafts), concourse level, entrances and exits, and commercial development. Through structural integration, the scale of open-cut construction is significantly reduced, minimizing the impact of open-cut construction on demolition, traffic, and the environment from the outset. Simultaneously, the above-ground portion of the vertical transportation core can be flexibly integrated with the development needs of surrounding plots, connecting entrances and exits with commercial facilities and transportation hubs, thereby improving the commercial operational efficiency and comprehensive service value of the rail transit system.

[0031] Example 2: This invention provides a method for the integrated construction of tunnels and stations in soft soil strata, comprising the following steps: S1. At the center of the station's designed location, construction will form a vertical traffic core 5; Based on the horizontal and vertical profiles of the railway line and the surrounding ground conditions of the proposed stations, sites with minimal demolition, few pipeline relocations, and minimal impact on traffic will be selected for the construction of vertical transportation cores. Construction methods for the vertical transportation cores can be selected based on the construction conditions, including open-cut, cut-and-cover, or mechanical shaft construction. The dimensions of the vertical transportation cores must meet the architectural functional requirements of the station hall, platforms, equipment rooms, and the originating points of the stations.

[0032] Open-cut or cut-and-cover construction is suitable for sites with favorable construction environments. For vertical access cores with limited site conditions or low passenger flow and small dimensions, mechanical shaft construction can be used. In this embodiment, the construction of vertical access core 5 adopts mechanical shaft construction technology, specifically including: S11. Ground reinforcement is carried out using jet grouting piles or mixing piles, and a ring foundation is poured on the outside of the wellhead; S12. Install the winch tower, settling unit (hydraulic jack + steel strand), and other devices, and construct the cutting edge and initial well body; S13. In-well hoisting main unit, equipped with telescopic boom and excavation tools; S14. The cutterhead cuts through the soil to carry out vertical tunneling in water. The outer wall of the vertical transportation core structure sinks synchronously with the excavation, and the inclinometer monitors and corrects the deviation. No dewatering is required during the excavation process to avoid affecting the surrounding buildings. S15. After excavating to the bottom of the pit, pour concrete to seal the bottom; and construct the internal structure of the vertical transportation core. Precast components can be used for partition walls, stairs, and floors to improve the convenience of construction.

[0033] S2. The vertical transportation core 5 serves as the starting working shaft, and large-diameter station tunnels 1 are excavated to both sides of the line. S3. After the large-diameter station tunnel 1 has been excavated to the preset length, the soil inside the tunnel is reinforced at the tunnel face. S4. Carry out diameter reduction construction work inside the reinforced tunnel and complete the excavation of the small-diameter section tunnel 2.

[0034] In this embodiment, after the main structure construction and end reinforcement construction of the vertical transportation core 5 are completed, the station tunnel construction will commence. When the ground construction site is limited and cannot meet the requirements for the separate launching site of the tunnel boring machine, the variable diameter top shield construction method can be adopted. Based on the geological conditions and the surrounding buildings, structures, and risk sources, either a slurry variable diameter top shield or an earth pressure balance variable diameter top shield will be selected.

[0035] In this embodiment, the variable-diameter top shield construction method is used to construct the large-diameter station tunnel and the small-diameter section tunnel: In S2, a variable-diameter shield tunneling machine was used to construct the large-diameter station tunnel 1 using the pipe jacking method; specifically: S2.1 Install temporary pipe jacking backrest reaction frame, pipe jacking machine jacking cylinder, assemble variable diameter shield machine, pipe jacking section and other devices in the vertical transportation core; S2.2, Install one section of shield tunneling steel segment, one top shield conversion ring, and one section of jacking steel segment in the top shield machine; S2.3 After installation, a large-diameter pipe jacking method is used to start the jacking excavation of the large-diameter station tunnel 1. Preferably, the pipe jacking section can be divided into three or four sections, which results in better overall performance.

[0036] In S4, the variable-diameter top shield machine is converted into a small-diameter shield machine, and the shield tunneling method is used to construct the small-diameter section tunnel 2. Specifically: S41. Within the diameter variation range at the end of the large-diameter station tunnel 1, grouting or freezing reinforcement is carried out inside the tunnel face to ensure the stability of the tunnel face; no ground reinforcement is required, reducing the impact of construction on ground traffic and demolition.

[0037] S42. Dismantle the connecting parts of the large and small cutterheads in the variable diameter tunnel boring machine and the connection between the large diameter tunnel boring machine and the shield body of the small diameter tunnel boring machine, so that the cutterhead and the shield body are separated. S43. Install the conversion ring and subsequent supporting mechanism for the starting of the small-diameter shield machine to complete the diameter conversion of the top shield machine; among them, the jacking pipe, shield segments and conversion ring (special steel ring) of the diameter-changing top shield machine can be installed in advance in the vertical traffic core, the amount of conversion work in the tunnel is small and the construction quality is high. S44. Use the small-diameter shield machine to start excavation and carry out the construction of the small-diameter section tunnel 2. After the construction is completed, the shield is received at a site with better construction conditions in the adjacent area.

[0038] Preferably, in this embodiment, such as Figure 7 and Figure 8 The diameter-changing construction operation is an eccentric diameter-changing operation, which makes the center line of the small-diameter section tunnel after the conversion not concentric with the center line of the large-diameter station tunnel. This realizes the connection between the subway track area of ​​the large-diameter station tunnel and the subway track area of ​​the small-diameter section tunnel, shortens the transition distance between the center line A of the subway track area of ​​the large-diameter station tunnel and the center line B of the subway track area of ​​the small-diameter section tunnel, reduces the length of the connecting tunnel, and lowers the project cost.

[0039] Example 3: The difference between this embodiment and Embodiment 2 is that this embodiment uses the mother-daughter shield tunneling method to construct the large-diameter station tunnel and the small-diameter section tunnel. Specifically: In S2, mother and daughter shield tunneling machines and supporting equipment are installed in the vertical transportation core, and a large-diameter shield tunneling machine is used for initial excavation. In S4, the large-diameter shield and the small-diameter shield of the mother and son tunnel boring machines are separated inside the tunnel, and a conversion ring is installed to switch to the small-diameter shield machine to continue excavation, completing the construction of the small-diameter section tunnel 2; specifically: After the completion of the S41 large-diameter station tunnel 1, the tunnel face will be reinforced by grouting or freezing within the diameter change range to ensure the stability of the diameter change face; no ground reinforcement is required, reducing the impact of construction on ground traffic and demolition. S42. Remove the connecting parts between the large and small cutterheads and the connecting parts between the mother and child shield bodies to separate the cutterheads and shield bodies; S43. Install conversion rings (special steel ring segments) as reaction force transfer for small shield jacking; adjust the supporting mechanisms of the shield machine to complete the diameter conversion of the parent and child shields and start the small diameter section shield. S44. The small-diameter shield tunneling machine after the diameter change will construct two sections of the small-diameter tunnel, and the shield will be received at a site with better construction conditions in the adjacent area.

[0040] The other parts of this embodiment are the same as those in Embodiment 2, and will not be repeated here.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A tunnel and station integrated structure suitable for soft ground, characterized in that, The large-diameter station tunnel (1), the small-diameter interval tunnel (2) and the vertical traffic core (5) are included. The vertical traffic core (5) is arranged in the middle of the station, the large-diameter station tunnel (1) is connected to the two sides of the vertical traffic core (5), and the small-diameter interval tunnel (2) is connected to the large-diameter station tunnel (1) through a connecting section. The large-diameter station tunnel (1) is provided with a subway track area (3) offset to one side and a station platform (4) beside the subway track area (3); and the small-diameter interval tunnel (2) is provided with a subway track area (3) in the middle. The connecting section is arranged at the end of the large-diameter station tunnel (1) and is used for eccentrically connecting the large-diameter station tunnel (1) and the small-diameter interval tunnel (2).

2. The integrated structure of a tunnel and a station for soft ground, according to claim 1, wherein The vertical traffic core (5) is a multi-layer structure combined with underground and aboveground, including a subway equipment room (5.1), a station transfer passage (5.6), a platform layer (5.7) arranged underground, a station hall (5.3), an entrance (5.4) and a commercial development space (5.5) arranged aboveground, and a vertical lifting elevator room (5.2) arranged through underground and aboveground, wherein the vertical lifting elevator room (5.2) is communicated with the subway equipment room (5.1), the station hall (5.3), the station transfer passage (5.6) and the platform layer (5.7).

3. The integrated structure of a tunnel and a station for soft ground according to claim 2, wherein The large-diameter station tunnel (1) is further provided with an interval pipe gallery (6) and a ventilation and smoke exhaust structure (7).

4. A method of constructing a tunnel-station integrated structure suitable for soft ground according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: S1, a vertical traffic core (5) is formed in the middle of the station design position; S2, the large-diameter station tunnel (1) is excavated to the two sides of the line from the vertical traffic core (5) as a starting work shaft; S3, after the large-diameter station tunnel (1) is excavated to a preset length, the in-hole soil is reinforced at the tunnel face; S4, the diameter is changed for construction and the small-diameter interval tunnel (2) is excavated.

5. The method of claim 4, wherein the tunnel and station integrated structure is constructed by the steps of: excavating a tunnel in a soft ground layer; installing a ground improvement structure in the soft ground layer; and constructing a station in the soft ground layer. In S1, the vertical traffic core (5) is constructed by using a mechanical vertical shaft construction process, which specifically comprises: S11, the foundation is reinforced on the ground, and a ring-shaped foundation is poured outside the wellhead; S12, an edge foot and an initial shaft body are constructed; S13, a main machine is hoisted in the shaft, a telescopic arm and an excavation cutter are configured; S14, the cutter head cuts the soil, vertical excavation construction with water is carried out, the structure outer wall of the vertical traffic core is synchronously sunk with excavation, and an inclinometer is used to monitor and correct deviation; S15, after excavation to the bottom of the foundation pit, the bottom is sealed by pouring concrete, and the internal structure of the vertical traffic core is constructed.

6. The method of constructing an integrated tunnel and station structure for soft ground according to claim 4, wherein The variable-diameter shield construction method is used for construction, specifically: In S2, the large-diameter station tunnel (1) is constructed by using a variable-diameter pipe jacking machine through pipe jacking; In S4, the variable-diameter pipe jacking machine is converted into a small-diameter shield machine, and the small-diameter interval tunnel (2) is constructed by using a shield method.

7. The method of claim 6, wherein the tunnel and station integrated structure is constructed by the steps of: excavating a tunnel in a soft ground layer; installing a ground improvement structure in the soft ground layer; and constructing a station in the soft ground layer. The large-diameter station tunnel (1) is constructed by using a variable-diameter pipe jacking machine through pipe jacking, specifically: S2.1, after a temporary pipe jacking backrest reaction frame, a pipe jacking machine jacking cylinder and a variable-diameter pipe jacking machine are assembled, a pipe jacking pipe section is assembled in the vertical traffic core; S2.2, install a section of shield steel pipe piece, top shield conversion ring, a section of top pipe steel pipe piece in the top shield machine; S2.3, after installation, use large diameter pipe jacking to start jacking.

8. The method of claim 6, wherein S4 Comprise: S41, in the variable diameter range at the end of the large diameter station tunnel (1), carry out in-situ grouting reinforcement or freezing reinforcement of the working face; S42, remove the connecting parts of the large and small cutter heads in the variable diameter top shield machine and the connecting parts between the large diameter pipe jacking machine and the shield body of the small diameter shield machine; S43, install the conversion ring and the rear matching mechanism for the launching of the small diameter shield machine, complete the variable diameter conversion of the top shield machine; S44, use the small diameter shield machine to start tunneling and construct the small diameter section tunnel (2).

9. The method of claim 4, wherein the tunnel and station integrated structure is constructed by the steps of: excavating a tunnel in a soft ground layer; installing a ground improvement structure in the soft ground layer; and constructing a station in the soft ground layer. The construction is carried out by using the parent-child shield construction method, specifically: In S2, the large diameter station tunnel (1) is constructed by using the parent-child shield machine; In S4, the large diameter shield body and the small diameter shield body in the parent-child shield machine are separated in the tunnel, and a conversion ring is installed to convert the machine into a small diameter shield machine to continue tunneling, thereby completing the construction of the small diameter section tunnel (2).

10. A method of constructing a tunnel and station integrated structure suitable for soft ground according to any one of claims 4 to 9, wherein The variable diameter construction operation is an eccentric variable diameter operation, so that the center line of the small diameter section tunnel after conversion is eccentric to the center line of the large diameter station tunnel, thereby realizing the connection between the large diameter station tunnel metro track area and the small diameter section tunnel metro track area.

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