A construction method for forming a station by using a shield tunnel expansion

Abstract

The application relates to a construction method for forming a station by expanding a shield tunnel, and relates to the underground construction field. The construction method comprises the following steps: constructing a shield well; performing shield tunnel construction in the shield well to form at least one shield tunnel; reinforcing the soil between the shield tunnels from the vertical well, and expanding the shield tunnels outward in sections to form cavities based on the shield tunnels; after constructing an initial support assembly in the cavities, constructing a main body structure and a platform in the cavities, and connecting the main body structure, the platform and the shield tunnels into an integrated whole. The shield tunnel is expanded to form the cavities, the size of the underground excavation section is reduced, the construction safety is improved, and the construction period is shortened. The equipment layer of the station can be arranged in combination with the shield well, and the station hall is connected to the station through a passage to form the entire station. The problems of starting a shield after a station is excavated in a complex site, a tunnel construction period lagging behind, a large station excavation scale, insufficient safety, poor economy and the like are solved.

Description

Technical Field

[0001] This invention relates to the field of underground construction engineering, and specifically to a construction method for forming a station by widening and excavating a shield tunnel. Background Technology

[0002] With urban development, subway stations have become a common mode of transportation for urban residents. The construction of underground stations includes tunnel construction and station platform construction, primarily employing the open-cut and tunnel-cut methods. The open-cut method involves excavating the surface, constructing the lining in an open-air environment, and then backfilling. The tunnel-cut method involves constructing the station without excavating the surface, using underground tunnels.

[0003] However, the cut-and-cover method has high requirements for the road surface. At some high-traffic intersections, if there are dense pipelines and some important pipelines that cannot be relocated, the conditions for constructing a cut-and-cover station are generally not suitable. On the other hand, the tunneling method for station construction has a long construction period, which can easily lead to idle work in the tunnel construction and seriously delay the tunnel construction schedule. In addition, the cross-section of tunneling stations is larger, which poses certain construction risks. Summary of the Invention

[0004] In related technologies, the construction methods for underground stations are limited by the road conditions in the construction area, making it difficult to use open-cut methods. Using cut-and-cover methods is slow, easily causing idle time in tunnel construction, and carries certain construction risks.

[0005] In a first aspect, this application provides a construction method for forming a station using shield tunnel widening, which includes the following steps:

[0006] Construction of the shield tunnel shaft;

[0007] Shield tunneling is carried out inside the shield shaft to form at least one shield tunnel;

[0008] The soil between the shield tunnels is reinforced, and a cavity is formed by excavating outward from the sidewall of the shield tunnel based on the shield tunnel.

[0009] After constructing the initial support components within the cavity, the main structure of the construction station is built, the platform is constructed within the cavity, and the platform is connected to the shield tunnel as a whole.

[0010] In conjunction with the first aspect, in one embodiment, the shield tunneling construction within the shield shaft to form at least one shield tunnel includes:

[0011] The shield tunneling is carried out longitudinally along the predetermined station location within the shield shaft to form two parallel shield tunnels located on both sides of the predetermined station location. The length of the shield tunnels exceeds the length of the predetermined station location.

[0012] In conjunction with the first aspect, in one embodiment, reinforcing the shield tunnel includes:

[0013] A pipe roof is constructed inside the shield shaft along the length of the shield tunnel, and the pipe roof corresponds to the position of the pre-designed station top surface.

[0014] The soil between tunnel sections, at the bottom, and at the top of the shield tunnel is reinforced.

[0015] Segments are laid on the wall of the shield tunnel to form an expansion ring plate, and steel supports are erected inside the shield tunnel to support the top surface of the expansion ring plate.

[0016] In conjunction with the first aspect, in one embodiment, the reinforcement of the soil between the tunnel sections, at the bottom, and at the crown includes:

[0017] The soil in the tunnel cavity, bottom, and arch of the shield tunnel was reinforced using a freezing method.

[0018] In conjunction with the first aspect, in one embodiment, the step of excavating outward from the sidewall of the shield tunnel to form a cavity based on the shield tunnel includes:

[0019] The cavity is excavated segment by segment along the length of the shield tunnel.

[0020] In conjunction with the first aspect, in one embodiment, the step of excavating outward from the sidewall of the shield tunnel to form a cavity based on the shield tunnel includes:

[0021] Open the side segments of the two shield tunnels at the corresponding construction sections and make openings;

[0022] The step method is used to excavate the upper part of the soil on the opening side of the shield tunnel to form a cavity, and the core soil inside the cavity is retained.

[0023] In conjunction with the first aspect, in one embodiment, the initial construction support assembly within the cavity includes:

[0024] A top support is erected along the pipe roof, and both ends of the top support are connected to the pipe segments on the surfaces of the two shield tunnels;

[0025] Excavate the core soil and the soil below the cavity, and erect a bottom support at the bottom of the cavity.

[0026] In conjunction with the first aspect, in one embodiment, both the bottom support and the top support are made of steel grating or grating steel frame.

[0027] In conjunction with the first aspect, in one embodiment, the construction platform within the cavity includes:

[0028] A platform is erected on the bottom support;

[0029] Erect columns on the platform and construct the station roof slab on the top surface of the columns.

[0030] In conjunction with the first aspect, in one embodiment, connecting the platform and the shield tunnel as a single unit includes:

[0031] Connecting bars are installed on the surface segments of the shield tunnel and connected to the platform and the roof of the station through the connecting bars.

[0032] The beneficial effects of the technical solutions provided in this application include at least the following:

[0033] In complex situations, this application allows for flexible placement of shield tunneling shafts in wider road areas, open spaces, or green areas for shield launching. The tunnel layout is determined based on the station line spacing. Shield tunnel construction begins longitudinally along the station. Once the tunnel length exceeds the station length, the sections requiring widening are supported by steel beams. The existing shield tunnel is then used to gradually widen the tunnel sections to form the station concourse. This method of utilizing the shield tunnel to create a cavity reduces the scale of the underground excavation, shortens the construction period, and improves construction safety. The station's equipment level can be integrated with the shield tunnel shafts, and auxiliary facilities can be arranged in conjunction with the surrounding site, connected to the concourse via passageways to form the entire station. Furthermore, by constructing pipe roofs or pipe curtains from the shield tunnel shaft towards the tunnel, depending on the geological conditions, the soil between the tunnel sections and the arch and bottom can be reinforced using methods such as freezing, grouting, MJS, and jet grouting. Then, the support effect of the completed shield tunnel is utilized, which reduces the cross-sectional scale of the underground excavation and takes advantage of the rapid, safe, and economical characteristics of shield tunneling. At the same time, it does not affect the tunnel breakthrough period. This solves the problems of starting the shield tunnel after the underground station is excavated in complex sites, resulting in delayed tunnel construction, large scale of underground station excavation, insufficient safety, and poor economy. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a top view of the shield tunnel and station in the embodiments of this application;

[0036] Figure 2 Appendix to this application specification Figure 1 A cross-sectional view from the perspective of the AA (American Academy of Sciences).

[0037] Figure 3Appendix to this application specification Figure 1 A cross-sectional view from the perspective of a BB (Black-White) camera.

[0038] In the diagram: 1. Shield shaft; 11. Retaining structure; 2. Shield tunnel; 21. Segment; 22. Connecting reinforcement; 3. Cavity; 4. Initial support components; 41. Top support; 42. Bottom support; 51. Excavation ring plate; 52. Steel support; 6. Core soil; 7. Platform; 71. Column; 72. Platform slab; 73. Station roof; 8. Pipe shed; 91. Ground layer; 92. Overburden layer. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0040] In related technologies, the construction methods for underground stations are limited by the road conditions in the construction area, making it difficult to use open-cut methods. Using cut-and-cover methods is slow, easily causing idle time in tunnel construction, and carries certain construction risks.

[0041] Firstly, such as Figure 1 As shown in the embodiment of this application, a construction method for forming a station using shield tunnel widening is provided. This method solves the problems of open-cut construction being limited by road conditions and cut-and-cover construction having long construction periods and safety risks during underground station construction. The construction method includes the following steps:

[0042] S1. Construction of shield tunnel shaft 1.

[0043] Specifically, such as Figure 3 As shown, the construction of shield shaft 1 includes constructing the main structure of shield shaft 1, erecting shield shaft supports, and setting up a retaining structure 11 on the side to ensure that shield shaft 1 meets the construction requirements.

[0044] Understandably, the construction location of shield shaft 1 can be flexibly arranged in combination with the route and site. Since the construction of shield shaft 1 has a small impact on the road surface area and can avoid complex road surfaces such as intersections with high traffic volume, the shield shaft construction can be carried out in an area with less impact on the road surface, thus not causing a significant impact on road traffic.

[0045] S2. Conduct shield tunneling within the shield shaft 1 to form at least one shield tunnel 2.

[0046] Specifically, shield tunneling is carried out longitudinally along the preset station location within the shield shaft 1 to form two shield tunnels 2 arranged in parallel on both sides of the preset station location. The length of the shield tunnel 2 exceeds the length of the preset station location. Segment 21 is installed in the contact layer between the shield tunnel 2 and the soil to complete the construction of the shield tunnel 2.

[0047] It should be noted that the construction of shield tunnel 2 requires the calculation of the predetermined station locations and the layout of the tunnel plan in conjunction with the station line spacing. Then, the shield machine is launched from the shield shaft 1 completed in step S1, and shield tunnel 2 is constructed longitudinally along the predetermined station locations until the length of shield tunnel 2 exceeds the length of the predetermined station locations, so that the construction personnel can excavate the station into its sidewalls within shield tunnel 2.

[0048] S3. Reinforce the soil of the shield tunnel 2, and excavate outward from the side wall of the shield tunnel 2 to form a cavity 3.

[0049] The aforementioned reinforcement of the soil in the shield tunnel 2 includes:

[0050] a. After the shield tunnel 2 construction is completed in step S2, as Figure 3 As shown, a pipe roof 8 or pipe curtain is constructed in the shield shaft 1 along the length of the shield tunnel 2. The pipe roof 8 or pipe curtain corresponds to the position of the top surface of the preset station and is located above the position of the preset station.

[0051] b. Soil reinforcement: Based on the geological conditions, the soil between the tunnel sections and the arch and bottom of the shield tunnel 2 are reinforced from inside the shaft.

[0052] Specifically, methods such as freezing, grouting, MJS, and jet grouting can be used to reinforce the soil between tunnel sections and at the top and bottom of the shield tunnel.

[0053] The principle of ground reinforcement using freezing methods involves artificially introducing a low-temperature refrigerant into the ground to freeze the soil around the excavation site into a closed, continuous frozen soil wall. This wall resists earth pressure and isolates groundwater from the excavation area. Excavation and permanent support are then carried out under the protection of this sealed, continuous frozen soil wall. The refrigerant, connected to the ground via inlet and outlet pipes, exchanges heat with the ground through the freezing pipes, transferring cold energy to the surrounding soil while carrying away heat. This causes the soil around the freezing pipes to gradually cool from near to far, turning the water in the soil into ice. The ice binds the previously loose or porous soil together, forming impermeable frozen soil columns. Several such freezing pipes are arranged, with the refrigerant continuously circulating within them, freezing the soil around them into frozen soil columns. As the radius of these frozen soil columns expands, adjacent columns connect, tightly bound together by ice to form a sealed, continuous wall.

[0054] Understandably, the freezing method for soil reinforcement possesses water-sealing properties, meaning that even free water (generally with a moisture content greater than 10%; otherwise, auxiliary methods to increase soil moisture are required) can freeze into frozen soil, forming a frozen soil wall. Whether it's a permeable layer or an impermeable layer, the frozen soil wall can prevent groundwater intrusion, creating a dry construction environment. Secondly, the soil has high strength. Frozen soil is generally considered a viscoelastic-plastic material, and its strength is related to factors such as soil type, density, moisture content, salinity, and temperature, generally reaching 2–10 MPa, far exceeding the strength of thawed soil, thus acting as a structural support wall. Furthermore, the freezing method for soil reinforcement is adaptable to various soil layers and various underground engineering projects, especially suitable for underground projects with high water content, weak strata, or where other construction methods are difficult or impossible. After construction, the soil layer returns to its original state with minimal damage. This is unparalleled by other methods. It has the ability to bypass obstacles for freezing reinforcement and water sealing. The freezing method uses electricity to generate cold energy, without polluting the atmosphere, emitting no harmful substances, or contaminating groundwater. Its advantages are particularly evident in projects with high environmental protection requirements. The freezing period, wall thickness, and shape are all controllable. The freezing method can be implemented in densely built-up areas and under existing structures without the need for foundation pit drainage, avoiding adverse effects on surrounding buildings caused by ground settlement due to pumping. The freezing method requires no support or anchors, allowing for open-plan construction, expanding the building area, and shortening the construction period.

[0055] Grouting is suitable for reinforcing foundations of sandy soil, silty soil, cohesive soil, and artificial fill. Before designing grouting reinforcement, it is advisable to conduct indoor grout mix proportion tests and on-site grouting tests to determine design parameters and verify construction methods and equipment; if there is local experience, design parameters can be determined according to local experience.

[0056] For grouting reinforcement of foundations, cement-based suspensions or two-component mixtures of cement and water glass can be used as grouting materials. For seepage prevention and plugging grouting, water glass, mixtures of water glass and cement, or chemical grouts can be used; environmentally polluting chemical grouts should be avoided. For foundation soil layers with groundwater flow, low-slump cement mortar can be used for compaction grouting, and drainage channels should be provided. The spacing of grouting holes should be determined based on field tests. Grouting holes can be arranged inside, outside, or within the foundation. After grouting within the foundation, measures should be taken to seal the holes. Grouting is simple to construct and has a wide range of applications. However, it requires a large amount of grouting material, which is expensive, resulting in higher costs. The effectiveness of grouting reinforcement is affected by various factors, such as ground conditions, the selection of grouting materials, and construction techniques; therefore, the effect is difficult to guarantee and requires close monitoring of the construction process.

[0057] c. Install the excavation support assembly inside the shield tunnel 2.

[0058] Specifically, such as Figure 2 As shown, pipe segments 21 are laid on the wall of the shield tunnel 2 to form an expansion ring plate 51, and steel brackets 52 are erected inside the shield tunnel 2 to support the top surface of the expansion ring plate 51.

[0059] Furthermore, an expansion ring plate 51 is formed in the area to be expanded within the tunnel and in each of the front and rear expansion segments 21, and is supported by a steel bracket 52 inside the shield tunnel 2.

[0060] The above-mentioned method of expanding the cavity 3 outward from the sidewall of the shield tunnel 2 based on the shield tunnel 2 includes: opening the segments 21 of the two shield tunnels 2 on the opening side, and expanding the cavity 3 from the sidewall of the two shield tunnels 2 towards the middle.

[0061] Specifically, the segments 21 on the sides of the two shield tunnels 2 at corresponding construction sections are opened and holes are made. The upper part of the soil on the opening side of the shield tunnel 2 is excavated using the step method to form a cavity 3, and the core soil 6 inside the cavity 3 is retained.

[0062] In some preferred embodiments, the cavity 3 is excavated segment by segment along the length of the shield tunnel 2 (or longitudinally along the predetermined station location).

[0063] Understandably, the excavation process can be carried out longitudinally in segments to improve construction efficiency. Specifically, the shield tunnel 2 can be longitudinally divided into multiple construction segments, each with a length of 6 to 12 meters. Segment construction can be carried out segment by segment, opening the tunnel segment 21 on the opening side of the segment, and the upper part can be excavated using the bench method, while retaining the core soil 6.

[0064] S4. After constructing the initial support component 4 in the cavity 3, construct the platform 7 and the main structure in the cavity 3, constructing them section by section, and connecting the main structure, platform and shield tunnel 2 into one.

[0065] The aforementioned initial support component 4 within cavity 3 includes the following steps:

[0066] Step A. Erect a top support 41 along the pipe roof 8, and connect the two ends of the top support 41 to the pipe segments 21 on the surface of the two shield tunnels 2.

[0067] Step B. Excavate the core soil 6 and the soil below the cavity 3, and erect a bottom support 42 at the bottom of the cavity 3.

[0068] Specifically, both the bottom support 42 and the top support 41 are made of steel grating or grating steel frame. After the top support 41 is erected, sprayed concrete is applied, and then the core soil 6 and the lower soil are excavated to construct the bottom support 42.

[0069] The aforementioned construction platform 7 and main structure within the cavity 3 include: the platform 7 being erected on the bottom support 42.

[0070] Specifically, the construction of the platform and main structure includes first constructing the station base slab, then the station bottom longitudinal beams, followed by the platform slab and the erection of the support frame. Columns 71 are then erected on the platform 7, and the station roof slab 73 is constructed on the top surface of the columns 71, thus completing the construction of the platform 7.

[0071] It is understandable that the above-mentioned process of erecting the platform and main structure can be carried out in sections to improve construction efficiency.

[0072] Furthermore, the above-mentioned integration of the main structure, platform 7, and shield tunnel 2 into a single unit includes: setting connecting bars 22 on the surface segments 21 of the shield tunnel 2, and connecting them to the platform 7 and the station roof slab 73 through the connecting bars 22. A steel bar joint is reserved at the end of the construction section before proceeding to the next section, until the entire station structure is completed, and then the steel support 52 inside the tunnel is removed.

[0073] Understandably, using the connecting reinforcement 22 to form a whole with the platform 7 structure improves the stability of the underground station excavation and greatly reduces the construction risk of the underground station.

[0074] On the other hand, such as Figure 2 As shown, this application provides an underground station, which includes: two parallel shield tunnels 2 and a platform 7 located in the two shield tunnels 2 and connected to the two shield tunnels 2.

[0075] In summary, under complex circumstances, this application allows for flexible placement of shield tunneling shafts in wider road areas, open spaces, or green areas for shield launching. The tunnel layout is determined based on station line spacing. Shield tunnel construction proceeds longitudinally along the station. Once the tunnel length exceeds the station length, the sections requiring widening are supported by steel beams. The existing shield tunnel is then used to gradually widen the tunnel sections to form the station concourse. Utilizing the shield tunnel to widen the cavities reduces the scale of the underground excavation, shortens the construction period, and improves construction safety. The station's equipment level can be integrated with the shield tunnel shafts, and auxiliary facilities can be arranged in conjunction with the surrounding site, connected to the concourse via passageways to form the entire station. Furthermore, by constructing pipe roofs or pipe curtains from the shield tunnel shaft towards the tunnel, depending on the geological conditions, the soil between the tunnel sections and the arch and bottom can be reinforced using methods such as freezing, grouting, MJS, and jet grouting. Then, the support effect of the completed shield tunnel is utilized, which reduces the cross-sectional scale of the underground excavation and takes advantage of the rapid, safe, and economical characteristics of shield tunneling. At the same time, it does not affect the tunnel breakthrough period. This solves the problems of starting the shield tunnel after the underground station is excavated in complex sites, resulting in delayed tunnel construction, large scale of underground station excavation, insufficient safety, and poor economy.

[0076] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0077] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A construction method for forming a station by using a shield tunneling method, characterized by, The method comprises the following steps: constructing a shield well (1); carrying out shield construction in the shield well (1) to form at least one shield tunnel (2); reinforcing the soil between the shield tunnels (2) and excavating a cavity (3) outside the sidewalls of the shield tunnels (2) based on the shield tunnels (2); constructing a primary support assembly (4) in the cavity (3), then constructing a station main structure and a platform (7) in the cavity (3), and connecting the main structure, the platform (7) and the shield tunnels (2) into an integrated whole; the step of carrying out shield construction in the shield well (1) to form at least one shield tunnel (2) comprises the following steps: carrying out shield construction in the shield well (1) along the longitudinal direction of a preset station position to form two shield tunnels (2) arranged in parallel on both sides of the preset station position, the length of the shield tunnels (2) exceeding the length of the preset station position; the step of reinforcing the soil between the shield tunnels (2) comprises the following steps: constructing a pipe shed (8) in the shield well (1) along the length direction of the shield tunnels (2), the pipe shed (8) corresponding to the top surface position of the preset station; reinforcing the soil between the shield tunnels (2), the bottom and the vault of the shield tunnels (2); laying a pipe segment (21) on the wall surface of the shield tunnels (2) to form an excavation ring plate (51), and erecting a steel formwork (52) in the shield tunnels (2) to support the top surface of the excavation ring plate (51).

2. The construction method according to claim 1, wherein the step of reinforcing the soil between the shield tunnels (2), the bottom and the vault of the shield tunnels (2) comprises the following step: reinforcing the soil between the shield tunnels (2), the bottom and the vault of the shield tunnels (2) by using a freezing method.

3. The construction method according to claim 1, wherein the step of excavating a cavity (3) outside the sidewalls of the shield tunnels (2) based on the shield tunnels (2) comprises the following step: excavating the cavity (3) in sections along the length direction of the shield tunnels (2).

4. The construction method according to claim 3, wherein the step of excavating a cavity (3) outside the sidewalls of the shield tunnels (2) based on the shield tunnels (2) comprises the following steps: opening the pipe segments (21) on the sidewalls of the corresponding construction sections of the two shield tunnels (2), and carrying out hole opening; excavating the upper part of the soil on the hole opening side of the shield tunnels (2) by using a bench method to form a cavity (3), and retaining the core soil (6) in the cavity (3).

5. The construction method according to claim 4, wherein the step of constructing a primary support assembly (4) in the cavity (3) comprises the following steps: erecting a top support (41) along the pipe shed (8), and connecting the two ends of the top support (41) with the pipe segments (21) on the surfaces of the two shield tunnels (2); excavating the core soil (6) and the soil in the lower part of the cavity (3), and erecting a bottom support (42) at the bottom of the cavity (3).

6. The construction method according to claim 5, characterized in that: The bottom support (42) and the top support (41) are both made of a steel lattice or a lattice steel frame.

7. The construction method according to claim 5, wherein the step of constructing a station main structure and a platform (7) in the cavity (3) comprises the following steps: building a platform deck (72) on the bottom support (42); erecting a stand column (71) on the platform deck (72), and constructing a station top plate (73) on the top surface of the stand column (71).

8. The construction method according to claim 7, wherein The main body structure, the platform (7) and the shield tunnel (2) are connected as a whole, which comprises: A connecting rib (22) is arranged on the surface segment (21) of the shield tunnel (2), and the segment (21) is connected with the platform (7) and the station roof (73) through the connecting rib (22).

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