A new prefabricated composite open-cut metro station structure with multiple space utilization and a construction method thereof

Abstract

The application discloses a novel prefabricated composite open-cut subway station structure with multiple space utilization and a construction method thereof, and relates to the technical field of urban rail transit underground engineering. The structure comprises a prefabricated pile, a crown beam, a station main body structure, an upper load-bearing structure and a retaining wall, and a space with a clear height of 3-6m can be utilized in the shallow layer above the station main body structure; the upper load-bearing structure comprises a prefabricated top column, a top column beam and a prefabricated top cover plate, the retaining wall is provided with a breakable part, a permanent side wall is formed by combining the steel bars, the post-poured concrete and the top cover plate, a rigid connection structure is adopted for a joint, and the station main body structure plate and the prefabricated top column can be used as construction supports. The application adopts a design of combining prefabricated composite with permanent and temporary structures, cancels a large amount of backfilling of earth at the top of the station, fully utilizes the shallow underground space, avoids repeated excavation of roads, and has the advantages of green and low carbon, high construction efficiency, high space utilization rate, low cost and the like, and is suitable for integrated construction of urban open-cut subway stations and comprehensive development of underground space.

Description

Technical Field

[0001] This invention relates to the field of urban rail transit underground engineering technology, and more specifically, to a novel prefabricated composite open-cut subway station structure with multi-space utilization and its construction method. Background Technology

[0002] With the development of urbanization in my country, the contradictions between population, resources, and transportation have become increasingly prominent, and "big city problems" have become an unavoidable governance challenge in the process of urbanization. Urban rail transit is an important solution to alleviate these problems, and the development of underground space has become an important part of the 21st century.

[0003] During the construction of underground stations for urban rail transit, a large amount of earthwork needs to be excavated during the foundation pit excavation. After the station structure is completed, a large amount of earthwork needs to be backfilled, and then pipelines are relocated, municipal roads are restored, and landscaping is carried out.

[0004] In the aforementioned open-cut method for constructing urban subway stations, the typical approach involves first constructing retaining structures (such as pile walls) around the foundation pit, then excavating the pit and constructing the main station structure, and finally backfilling a large volume of earthwork above the main station structure to restore surface roads or green spaces. This traditional construction method results in a significant waste of underground space resources, as a large amount of valuable underground space is buried beneath the main station structure. Existing technologies have not provided effective solutions to the above problems. In response to the national requirements for green and low-carbon construction, this invention proposes a novel prefabricated composite open-cut subway station structure with multi-space utilization and its construction method, which makes full use of the reserved space above the station constructed by the open-cut method to achieve intensive and maximized resource utilization. Summary of the Invention

[0005] The purpose of this invention is to solve the problems mentioned in the background art, and to propose a novel prefabricated composite open-cut subway station structure with multi-space utilization and its construction method.

[0006] The technical solution adopted by this invention to solve its technical problem is: A novel prefabricated composite open-cut subway station structure with multi-space utilization includes: Precast piles located around the foundation pit, and capping beams connecting the tops of the precast piles; The main structure of the station is located in an open-cut foundation pit. Above the main structure of the station, a shallow usable space with a clearance height of 3m to 6m is formed, which can be used for municipal utility tunnels, underground commercial spaces, parking, or traffic transfers. The upper load-bearing structure supporting the main structure of the station includes multiple precast top columns, top column beams erected between adjacent top columns, and precast top cover plates laid on the top column beams. A retaining wall is set along the side wall of the open excavation pit. The retaining wall has a breakable part. The steel bars in the breakable part are connected to the precast top cover plate and are combined with the precast top cover plate by post-poured concrete to form a permanent side wall that protects the shallow usable space. Among them, the precast top cover plate and the top column beam are rigidly connected by the connection of the reserved steel bars and the post-cast concrete of the side support of the top cover plate and the post-cast concrete of the middle support of the top cover plate. The main structure of the station includes a base slab, a middle slab, and side walls. At least one structural slab serves as both a horizontal internal support and a construction formwork, while the precast top columns also function as vertical supports.

[0007] Furthermore, the top column beam is a prestressed concrete beam.

[0008] Furthermore, one or more supporting brackets are pre-installed on the retaining wall.

[0009] Furthermore, at least one metal or rubber waterstop is pre-embedded at the vertical construction joint between the removable and retained portions of the retaining wall.

[0010] Furthermore, the waterstop at the vertical construction joint is continuously installed along the entire length of the foundation pit.

[0011] Furthermore, it also includes a top column foundation set on the bottom plate of the main structure of the station for installing the top column. The top column foundation and the bottom plate are connected by a top column foundation post-pouring strip, and the interface of the top column foundation post-pouring strip is provided with a waterproof structure.

[0012] Furthermore, the top column is a precast concrete column, and the top column is connected to the top column foundation by pre-embedded steel bars or bolts.

[0013] The above-described construction method includes the following steps: S1: Construction of precast piles, capping beams and retaining walls; S2: Layered open-cut foundation pit excavation, with support as excavation progresses; after excavation to the bottom slab elevation, construct the bottom slab and side walls; continue excavation to the middle slab elevation and construct the middle slab, which also serves as horizontal internal support during the foundation pit excavation stage; install precast top columns simultaneously or in stages, which also serve as vertical supports to ensure the safety of foundation pit construction. S3: Construction of top columns and top column beams; S4: Install the prefabricated top cover; S5: Connect the soil-facing side reinforcement of the retaining wall to the soil-facing side reinforcement of the top cover plate, and pour the post-cast concrete of the side support of the top cover plate and the post-cast concrete of the middle support of the top cover plate to form a rigid connection node between the permanent side wall and the precast top cover plate.

[0014] Furthermore, during the construction of the retaining wall in S1, support brackets are pre-installed at positions corresponding to the design installation elevation of the top column beam; The construction method also includes: after excavating the foundation pit to below the supporting corbel and completing the bottom slab construction, installing the temporary support structure on the supporting corbel of the retaining walls on both sides; At the same time or after the construction of the main structure of the station, the top column beam is hoisted, so that one end of the top column beam is supported on the top of the top column and the other end is supported on the temporary support structure. Subsequently, the subsequent construction of the station's main structure and the installation of prefabricated top cover plates were carried out in parallel.

[0015] Furthermore, the temporary support structure is removed after the top column beam is installed in place and reaches its design strength. Compared with the prior art, the beneficial effects of the present invention are: In the novel precast composite open-cut subway station structure and its construction method for multi-space utilization as described in this invention, an upper load-bearing structure consisting of precast top columns, top column beams and precast top cover plates is set above the main structure of the station, and a removable part is set on the retaining wall to form a permanent side wall in combination with the precast top cover plate, which together enclose a shallow utilization space located underground with a complete structure.

[0016] This design eliminates the need for traditional backfilling after the main station structure is completed, thus directly avoiding the waste of space resources caused by backfilling. This shallow space can be used for various purposes such as municipal utility tunnels, commercial development, or traffic transfer, achieving intensive use of underground space.

[0017] Meanwhile, due to the formation of a stable and permanent superstructure, subsequent pipeline laying or relocation will not require large-scale and repetitive excavation of the upper ground, reducing secondary interference with municipal traffic and saving construction costs. According to engineering calculations, compared with traditional open-cut subway stations, this invention shortens the construction period by 15%–25%, reduces project costs by 10%–20%, increases the utilization rate of underground space by more than 40%, and reduces carbon emissions by more than 20%.

[0018] In addition, the use of precast components and rigid connections with cast-in-place concrete at key nodes, as well as the utilization of some components of the station's main structure as a support system during the construction period, effectively improved construction efficiency and project quality. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a novel prefabricated composite open-cut subway station with multi-space utilization according to the present invention. Figure 2 This is a schematic diagram of the joint between the retaining wall and the top cover plate; Figure 3 A schematic diagram of the top column, top cover plate, and station structural nodes; Figure 4 This is a schematic diagram of the top column foundation. Figure label: 1. Precast piles; 2. Crown beam; 3. Main structure of the station; 4. Retaining wall; 41. Support corbel; 42. Demolishable section; 43. Reinforcing steel on the soil-facing side of the retaining wall; 5. Top cover plate; 51. Reinforcing steel on the soil-facing side of the top cover plate; 52. Post-cast concrete for the side supports of the top cover plate; 53. Post-cast concrete for the central supports of the top cover plate; 6. Top column; 7. Top column foundation; 71. Post-cast strip for the top column foundation; 8. Top column beam. Detailed Implementation

[0020] 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 them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The present invention will be further described with reference to the accompanying drawings and embodiments: After the completion of traditional open-cut subway station construction, a large amount of earthwork is often required to backfill the area above the station roof to restore surface functionality. This not only results in a huge waste of valuable shallow underground space but also brings many problems such as repeated excavation and traffic disruptions due to subsequent pipeline relocation. This invention aims to construct a usable, structurally complete shallow space directly above the main station structure 3 through an innovative structural design and construction method. This fundamentally avoids large-scale earthwork backfilling, achieves intensive and multi-functional utilization of underground space, and significantly reduces the interference of subsequent municipal construction on the surface.

[0021] Figure 1 The figure illustrates the overall structure of a novel prefabricated composite open-cut subway station structure with multi-space utilization according to a preferred embodiment of the present invention. As shown in the figure, the embodiment of the present invention provides a novel prefabricated composite open-cut subway station structure with multi-space utilization. Its core idea is that, while or after the construction of the main station structure 3 is completed, a permanent superstructure is constructed on top of it. This structure, together with the modified foundation pit retaining structure, forms a closed, shallow space that can be used for subsequent development.

[0022] Specifically, the structure includes precast piles 1 located around the foundation pit, and capping beams 2 connected to the top of the precast piles 1, together forming the initial retaining system of the foundation pit. Inside the open-cut foundation pit, the main station structure 3 is constructed, which includes a bottom slab, a middle slab, and side walls. Unlike traditional structures, in this invention, the main station structure 3 is not covered by backfill soil, but is supported and enclosed by a specially constructed superstructure, thus directly forming a complete shallow usable space. The clear height of this space can be flexibly designed according to future planned uses (such as municipal integrated utility tunnels, underground commercial streets, bicycle parking lots, or transportation transfer halls), typically ranging from 3 to 6 meters.

[0023] The superstructure supports the main station structure 3 and functions to bear the soil load on the top of the shallow usable space, ground live loads (such as vehicle loads), and transfer them to the main station structure 3 and the foundation. This superstructure mainly includes multiple precast columns 6, column beams 8 erected between adjacent precast columns 6, and precast top cover slabs 5 laid on top of the column beams 8. The precast top cover slab 5, as the "top slab" of the shallow usable space, directly bears the overlying load. The column beams 8 transfer the load of the precast top cover slab 5 to the precast columns 6. The precast columns 6, as vertical load-bearing components, ultimately transfer the load to the bottom slab of the main station structure 3 below them or to the foundation through dedicated column foundations 7.

[0024] To achieve lateral enclosure of shallow-utilized space, this invention features an innovative design for the retaining wall 4 installed along the sidewall of the open-cut excavation pit. This retaining wall 4 is not completely demolished or abandoned after construction; instead, it is designed with a removable portion 42. In the later stages of construction, only the concrete of this removable portion 42 is removed, retaining the retaining wall's frontal reinforcement 43. Then, these reserved frontal reinforcement 43 are reliably connected (e.g., by welding or mechanical connection) to the frontal reinforcement 51 of the precast top cover 5, and the post-concrete concrete for the side support is poured together.

[0025] The post-cast concrete of the side supports tightly integrates the soil-facing reinforcement 43 of the retaining wall, the soil-facing reinforcement 51 of the top cover plate, and the retained portion of the retaining wall 4, thus transforming a part of the original temporary retaining wall 4 used for foundation pit construction into a permanent side wall protecting the shallow usable space. This design cleverly combines temporary retaining structures with permanent usable structures, avoiding waste of resources and simplifying the construction process.

[0026] To ensure the integrity and stability of the entire superstructure, the precast top cover plate 5 is rigidly connected to the top column beam 8 and / or retaining wall 4 through the connection of reserved steel bars and the subsequent pouring of concrete.

[0027] Specifically, this is reflected in two key nodes: First, the connection node between the precast top cover plate 5 and the permanent side wall formed by the retaining wall 4 is rigidly connected through the aforementioned top cover plate soil-facing side steel bar 51, retaining wall soil-facing side steel bar 43 and side support post-cast concrete. Secondly, the support node of the precast top cover plate 5 above the top column beam 8 is connected to the precast steel bars at the bottom of the precast top cover plate 5 and the top column beam 8, and the post-cast concrete of the intermediate support is poured to form a rigid connection. This composite connection method of "precast component + post-cast concrete wet joint" not only gives full play to the advantages of precast component factory production, high quality and short construction period, but also ensures the integrity and seismic performance of the node area through the on-site post-cast concrete.

[0028] Another important feature of this invention is the integrated design of the support system during construction. The main structure 3 of the station includes a bottom slab, a middle slab, and side walls. During the construction phase, at least one structural slab (usually the middle slab) is designed to serve the dual functions of horizontal internal support and construction formwork. That is, during the excavation of the foundation pit, once the elevation of the middle slab is revealed, that middle slab is immediately constructed. At this time, the already cast middle slab acts as a strong horizontal support beam, supported at both ends by the constructed side walls or retaining walls 4, effectively resisting the soil pressure on the side walls of the foundation pit, replacing or partially replacing traditional steel or concrete supports, thereby saving a significant amount of temporary support materials and installation / dismantling procedures. Simultaneously, the middle slab also serves as a working platform or formwork support foundation during the construction of its upper structure (such as the top slab, which in this invention is the prefabricated top cover slab 5 system). Furthermore, after installation, the prefabricated top column 6 also serves as a vertical support during the construction phase, forming a stable spatial support system together with the middle slab and other horizontal components, ensuring safety during foundation pit excavation and main structure construction. This "permanent-temporary combination" design concept significantly improves material utilization efficiency and reduces engineering costs.

[0029] In a preferred embodiment, the top column beam 8 is a prestressed concrete beam. By pre-applying pressure to the tension zone of the member, the prestressed concrete top column beam 8 can significantly improve the beam's bending resistance and stiffness, enabling the use of smaller cross-sectional dimensions or the achievement of a larger column grid span under the same load and span conditions.

[0030] For shallow-use spaces, the use of prestressed top-column beams 8 facilitates the creation of more open and regular column-free or column-less spaces, improving the quality and flexibility of space use and allowing for flexible partitioning and arrangement according to future needs. Compared to ordinary reinforced concrete beams, prestressed beams also have advantages in controlling deformation and cracking, ensuring the long-term flatness and durability of the precast top cover 5.

[0031] Of course, depending on the specific span, load, and economic considerations of the project, the top column beam 8 can also be a regular reinforced concrete beam. Regular reinforced concrete beams are relatively simple to construct and install, requiring no prestressing tendons, and are suitable for smaller spans or lighter loads. The choice between the two options needs to be determined based on comprehensive design conditions.

[0032] As shown in the figure, in this embodiment, one or more supporting brackets 41 are pre-cast on the retaining wall 4. These supporting brackets 41 are protruding structures pre-cast on the wall surface facing the inside of the foundation pit during the pouring of the retaining wall 4.

[0033] The main function of the supporting bracket 41 is to provide a temporary intermediate support point for the installation of the top column beam 8 during the construction phase. Since the top column beam 8 usually has a large span, its self-weight and construction load may cause downward deflection or even instability before the precast top column 6 is fully installed or its strength meets the design requirements.

[0034] By pre-setting support brackets 41 on the retaining wall 4 and erecting temporary support structures (such as steel supports or prefabricated support frames) on the brackets, a reliable temporary support can be provided for one end of the top column beam 8 (the end closest to the pit sidewall). This allows the hoisting and placement of the top column beam 8 to be carried out earlier and more safely, creating conditions for the subsequent installation of the prefabricated top cover 5, thereby potentially enabling the construction of the station's main structure 3 and the superstructure to proceed in parallel, shortening the overall construction period.

[0035] If the project is small in scale, the span of the top column beam 8 is not large, or other reliable temporary support schemes are adopted (such as erecting full-span scaffolding from the base slab), then the supporting corbel 41 may not be required. The option of setting the supporting corbel 41 increases the complexity of the prefabrication or cast-in-place construction of the retaining wall 4, but brings improvements in construction flexibility and safety.

[0036] To ensure the waterproof reliability of the retaining wall 4 during the process of breaking up part of the concrete to form a permanent side wall, the present invention pre-embeds at least one waterstop (not shown in the figure) at the vertical construction joint between the breakable part 42 and the retained part of the retaining wall 4.

[0037] The waterstop is preferably a metal waterstop (such as a galvanized steel plate waterstop) or a rubber waterstop. This waterstop is pre-fixed in its designed position before the concrete of the retaining wall 4 is poured, with one part embedded in the breakable section 42 and the other part embedded in the retained section. When the concrete of the breakable section 42 is subsequently removed, the pre-embedded waterstop will remain intact at the edge of the retained section and will be tightly bonded to the subsequently poured concrete of the edge support, forming a continuous waterproof barrier. This barrier effectively prevents groundwater or moisture in the soil from seeping into the shallow usable space along the interface between the new and old concrete (i.e., the vertical construction joint), ensuring the dryness and usability of the space.

[0038] Furthermore, to ensure the integrity of the waterproofing, the waterstop at the vertical construction joints is preferably installed continuously along the entire length of the foundation pit. That is, along the entire length of the station, in all sections where the retaining wall 4 needs to be converted into a permanent side wall, a continuous waterstop is installed within the vertical construction joints, eliminating any possible weak points in the waterproofing. For areas with extremely high waterproofing requirements, even two waterstops of different materials or types can be installed to form multiple lines of defense against water damage. If waterstops are not installed or are discontinuous, groundwater may seep along the construction joints, affecting the usability of the shallow usable space and potentially corroding the internal steel reinforcement, reducing structural durability.

[0039] To effectively and stably transfer the load of the superstructure to the foundation and coordinate deformation with the base slab of the station main structure 3, this embodiment of the invention also includes a top column foundation 7 installed on the base slab of the station main structure 3 for installing precast top columns 6. The top column foundation 7 is an independent concrete foundation block, typically square or rectangular. The top column foundation 7 is not integrally cast with the base slab of the station main structure 3, but is connected via a post-cast strip 71. The post-cast strip 71 is a strip-shaped gap reserved during the construction of the base slab. After most of the base slab concrete shrinkage has occurred and the settlement of the top column foundation 7 has relatively stabilized, micro-expansion concrete is poured to fill and seal it. This post-cast connection method can effectively release the temperature and shrinkage stresses generated during the early construction of the base slab, reducing cracks caused by these stresses. It can also accommodate minor uneven settlement that may exist between the base slab and the top column foundation 7, avoiding excessive secondary stress in the base slab. To prevent groundwater from seeping in through the interface of the post-cast strip 71, a special waterproof structure is provided at the interface of the post-cast strip 71.

[0040] The waterproof structure can include various forms such as pre-embedded water-stop steel plates, water-swellable water-stop strips, or cement-based penetrating crystalline waterproof coatings applied to the interface to ensure the waterproof sealing of the joints.

[0041] In this embodiment, the precast top column 6 is preferably a reinforced concrete column precast in a factory, which has the advantages of precise dimensions, stable quality, and smooth surface. The installation of the precast top column 6 depends on its reliable connection with the top column foundation 7.

[0042] There are two main types of connection methods: one is the connection through pre-embedded steel bars. That is, vertical steel bars are pre-embedded at the bottom of the precast top column 6 and on the top surface of the top column foundation 7. During installation, the precast top column 6 is hoisted into place, the pre-embedded steel bars are aligned, and then high-strength grout or fine stone concrete is poured in the joint area to form a firm connection.

[0043] Another type is bolted connection. Anchor bolts are pre-embedded on the top surface of the foundation 7, and corresponding bolt holes or connecting plates are pre-drilled at the bottom of the precast top column 6. After hoisting into place, the column is fixed by tightening nuts. Pre-embedded steel reinforcement connection provides good overall integrity and excellent seismic performance; bolted connection offers faster installation and is easier to adjust and replace. The specific method used needs to be determined comprehensively based on the structural stress requirements, construction conditions, and design practices. The precast top column 6 can also be in the form of steel pipe concrete column or steel-concrete composite column, and its connection to the foundation can be welded or bolted accordingly.

[0044] Based on the aforementioned novel prefabricated composite open-cut subway station structure with multi-space utilization, this invention also provides a corresponding efficient construction method. This construction method has a clear logic, fully utilizes the "permanent-temporary combination" characteristic of the structure, and achieves dual optimization of space utilization and construction efficiency.

[0045] The construction method includes the following core steps: S1: Construction of precast pile 1, capping beam 2 and retaining wall 4.

[0046] First, precast piles 1 are driven or implanted around the planned station foundation pit as retaining piles, and then capping beams 2 are constructed on top of the piles to connect them into a whole. Next, retaining walls 4 are constructed along the edge of the foundation pit. In this step, according to the design, pre-embedded parts for supporting corbels 41 need to be installed in the retaining wall 4 in advance or the supporting corbels 41 need to be directly cast to form them. At the boundary between the removable part 42 and the retained part of the retaining wall 4 (i.e., at the vertical construction joint), a continuous waterstop is accurately pre-embedded.

[0047] S2: The open-cut foundation pit is excavated in layers, with support provided as excavation progresses. After excavating to the corresponding elevation, the bottom slab, middle slab, and corresponding side walls are constructed sequentially. After reaching the bottom slab elevation, the bottom slab is constructed. Excavation continues upwards until the bottom elevation of the designed middle slab is reached. Excavation is then paused, and the middle slab and side walls within that layer are constructed. At this point, the newly poured middle slab acts as the horizontal internal support for the deeper excavation layer. Precast top columns 6 can be installed in place according to the hoisting plan during this stage and participate in the foundation pit support system as vertical supports. This step enables the structural slab (middle slab) of the station's main structure 3 to function as both horizontal internal support and construction formwork, and the precast top columns 6 to also serve as vertical supports.

[0048] S3: Construct the precast top column 6 and top column beam 8. Construct the top column foundation 7 on the base slab (or construct it simultaneously with the base slab but leave a post-cast strip 71 for the top column foundation), then hoist the precast top column 6 and reliably connect it to the top column foundation 7. Subsequently, hoist the top column beam 8. One end of the top column beam 8 is supported on top of the installed precast top column 6, while the other end may require temporary support.

[0049] S4: Install the precast top cover plate 5. After the top column beam 8 is installed in place and forms a stable support, the precast top cover plate 5 can be hoisted and laid on the top column beam 8.

[0050] S5: Forming a permanent structural node. This step is crucial. First, break the concrete of the removable section 42 of the retaining wall 4, which is planned to be converted into a permanent side wall, carefully preserving the retaining wall's frontal reinforcement 43 inside. Then, securely connect the exposed frontal reinforcement 43 of the retaining wall to the frontal reinforcement 51 of the precast top cover 5 extending from its edge.

[0051] Finally, the post-cast concrete for the side supports and the post-cast concrete for the middle supports at the supports of the precast top cover 5 are poured. After the post-cast concrete reaches the design strength, the retained part of the retaining wall 4 and the precast top cover 5 are connected together by rigid joints to form a complete and permanent box-shaped structure for the shallow utilization space of the retaining wall. After that, the post-cast strip 71 of the top column foundation can be poured and closed.

[0052] As an optimization of the basic construction method described above, during the construction of the retaining wall 4 in S1, supporting brackets 41 were pre-installed at the positions corresponding to the design installation elevation of the top column beam 8. The construction method can then be further enhanced by: after excavating the foundation pit to below the supporting brackets 41 and completing the bottom slab construction, installing temporary support structures (such as large steel beams or prefabricated support frames) on the supporting brackets 41 opposite the retaining walls 4 on both sides of the foundation pit, forming a reliable intermediate temporary support line. Then, simultaneously with or after the construction of the middle slab of the station's main structure 3, the top column beam 8 can be hoisted. At this time, one end of the top column beam 8 is supported on the top of the precast top column 6, and the other end is directly supported on the temporary support structure. In this way, the installation of the top column beam 8 system no longer requires waiting for the station's main structure 3 to reach a high elevation or for the construction of complex full-span support frames, allowing for earlier intervention. Subsequently, the construction of subsequent layers (if any) of the station's main structure 3 and the installation of the precast top cover slab 5 can be carried out in parallel, achieving "synchronous" construction of the underground multi-layer structure and significantly reducing the overall construction period. Once the temporary support structure is installed in place at the top column beam 8 and its connection with the precast top column 6 (which may require pouring post-cast concrete) reaches sufficient design strength to independently bear the load, it can be safely dismantled and recycled for reuse.

[0053] In summary, this invention, through innovative structural system design, transforms the backfill space above cut-and-cover subway stations into usable shallow space with a permanent retaining structure, completely avoiding the waste of earthwork backfilling. By employing a series of technologies such as prefabricated composite structures, permanent-temporary combination, and rigid joint connections, construction efficiency is significantly improved and the total life-cycle cost is reduced while ensuring structural safety and durability. The resulting shallow usable space provides a new platform for the comprehensive development of urban underground space, yielding significant socio-economic benefits.

[0054] The orientation or spatial relationships involved in this application, such as "top," "bottom," "upper," "lower," "inner," "outer," "side," "vertical," and "horizontal," are all defined based on the perspective shown in the accompanying drawings. These expressions are intended only to simplify the description of the technical solutions of this invention and are not intended to imply or indicate that the elements referred to must be in a specific orientation or constructed and operated in a specific order. Therefore, the orientation terms mentioned herein should not be regarded as absolute limitations on the claims.

[0055] In the description of this application, terms such as "installation," "connection," "coupling," "fixing," "supporting," "laying," "pouring," "breaking," and "embedding" should be interpreted broadly. Specifically, a connection can be a fixed connection, a detachable connection, or even a structurally integral molding; it can refer to physical mechanical contact or a rigid bond achieved through steel bars or concrete; furthermore, a connection includes both direct connection and indirect connection achieved through an intermediate medium (such as grout or post-poured concrete). The order of construction procedures can be reasonably adjusted or partially parallelized, provided that the technical logic allows. For those skilled in the art, the precise meaning of the above terms in this application can be determined based on the specific context and technical logic.

[0056] It should be clarified that the foregoing embodiments are merely representative examples of this application and do not constitute an exclusive definition of the scope of protection of this invention. For those skilled in the art, any conventional changes such as local optimization, functional equivalent substitution, or detailed modifications made without departing from the core concept of this application (i.e., constructing a permanent superstructure above the main station structure 3 and forming a shallow usable space with the modified retaining wall 4), such as adjusting the specific dimensions of precast components, changing the strength grade of the post-cast concrete, using different waterproofing materials, or optimizing the selection of construction machinery, should be included within the scope of the claims of this application.

Claims

1. A novel prefabricated composite open-cut subway station structure with multi-space utilization, characterized in that, include: Precast piles (1) located around the foundation pit, and capping beams (2) connecting the top of the precast piles (1); The main structure of the station (3) is located in the open-cut foundation pit, and a shallow usable space with a clearance height of 3m to 6m is formed above the main structure of the station (3); The upper load-bearing structure supported above the main structure (3) of the station includes multiple precast top columns (6), top column beams (8) erected between adjacent top columns (6), and precast top cover plates (5) laid on the top column beams (8). A retaining wall (4) is set along the side wall of the open excavation pit. The retaining wall (4) has a breakable part (42). The steel bars in the breakable part (42) are connected to the precast top cover plate (5) and are combined with the precast top cover plate (5) by post-poured concrete to form a permanent side wall for protecting the shallow utilization space. Among them, the precast top cover plate (5) and the top column beam (8) are rigidly connected by the connection of the reserved steel bars and the post-cast concrete (52) of the side support of the top cover plate and the post-cast concrete (53) of the middle support of the top cover plate. The main structure of the station (3) includes a bottom slab, a middle slab and side walls, of which at least one structural slab serves as both a horizontal internal support and a construction template, and the precast top column (6) serves as a vertical support.

2. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 1, characterized in that, The top column beam (8) is a prestressed concrete beam.

3. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 1, characterized in that, One or more supporting brackets (41) are pre-installed on the retaining wall (4).

4. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 1, characterized in that, At least one waterstop is pre-embedded at the vertical construction joint between the breakable part (42) and the retained part of the retaining wall (4).

5. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 4, characterized in that, The waterstop at the vertical construction joint is continuously installed along the entire length of the foundation pit.

6. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to any one of claims 1 to 5, characterized in that, It also includes a top column foundation (7) set on the bottom plate of the main structure (3) of the station for installing the top column (6). The top column foundation (7) is connected to the bottom plate by a top column foundation post-pouring strip (71), and the interface of the top column foundation post-pouring strip (71) is provided with a waterproof structure.

7. The novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 6, characterized in that, The top column (6) is a precast concrete column, and the top column (6) is connected to the top column foundation (7) by pre-embedded steel bars or bolts.

8. A construction method for a novel prefabricated composite open-cut subway station structure with multi-space utilization as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Construction of precast piles (1), capping beams (2) and retaining walls (4); S2: Layered excavation of open-cut foundation pit, with support as excavation progresses; construction of the bottom slab and side walls after excavation to the bottom slab elevation; construction of the middle slab after excavation to the middle slab elevation, with the structural slab serving as horizontal internal support during the foundation pit excavation stage; installation of precast top columns (6) simultaneously or in stages, serving as vertical support. S3: Construction of the top column (6) and the top column beam (8); S4: Install the prefabricated top cover (5); S5: Connect the soil-facing side reinforcement (43) of the retaining wall to the soil-facing side reinforcement (51) of the top cover plate, and pour the post-cast concrete (52) of the side support of the top cover plate and the post-cast concrete (53) of the middle support of the top cover plate to form a rigid connection node between the permanent side wall and the precast top cover plate (5).

9. The construction method for a novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 8, characterized in that, When constructing the retaining wall (4) in S1, a support bracket (41) is pre-installed at the position corresponding to the design installation elevation of the top column beam (8). The construction method also includes: after excavating the foundation pit to below the supporting corbel (41) and completing the bottom slab construction, installing the temporary support structure on the supporting corbel (41) of the retaining walls (4) on both sides; At the same time or after the construction of the main structure (3) of the station, the top column beam (8) is hoisted so that one end of the top column beam (8) is supported on the top of the top column (6) and the other end is supported on the temporary support structure; Subsequently, the construction of the main station structure (3) and the installation of the prefabricated top cover plate (5) were carried out in parallel.

10. The construction method for a novel prefabricated composite open-cut subway station structure with multi-space utilization according to claim 9, characterized in that, The temporary support structure is removed after the top column beam (8) is installed in place and reaches the design strength.

Images