Construction method of narrow site metro station construction assembly type temporary support structure

Abstract

The application is a construction method of a narrow site subway station construction assembly type temporary support structure, comprising the following steps: site preparation and traffic guide change; constructing a construction diaphragm wall on the construction side, and drilling a hole and inserting a hole I-beam module at a predetermined position; pouring a solidified material at the lower part to form an uplift pile, and backfilling at the upper part; layer-by-layer excavating a foundation pit, layer-by-layer installing a prefabricated concrete retaining unit composed of first and second prefabricated concrete modules as excavation progresses, longitudinally butting the modules through female and male joints, transversely splicing the modules through a mortise and tenon structure, and screwing the modules with the I-beam module to form a temporary support system; after completing excavation on one side, building a truss and a cover plate to restore traffic, and then sealing the construction diaphragm wall on the other side; layer-by-layer excavating and layer-by-layer removing and recycling the prefabricated modules; finally, converting the upper I-beam module into a permanent composite intermediate column to complete the station structure and restore the traffic. The application has the advantages of convenient construction, adaptation to narrow sites, reusability, environmental protection, etc.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support technology, and in particular to a construction method for a prefabricated temporary support structure for subway station construction in a confined space. Background Technology

[0002] With the rapid development of urban rail transit construction, subway station projects are widely distributed in the core areas of cities, surrounded by dense buildings, complex underground pipelines, and limited construction sites. Under such conditions, when constructing deep foundation pits and main structures, temporary support structures not only need to meet high requirements for structural safety and deformation control, but also need to take into account the flexibility of construction organization, site utilization efficiency, and economy.

[0003] Existing temporary support structures are mostly for single use. Cast-in-place reinforced concrete support structures usually need to be separated from or demolished from the main structure, resulting in long construction cycles, significant material waste, and difficulty in component recycling and reuse. Furthermore, existing support systems are not well-suited to confined construction sites. Under limited space, the installation, dismantling, and transportation of support components are restricted. Traditional support methods often require large hoisting spaces and working areas, leading to significant construction interference and impacting the progress of the main structure. Simultaneously, complex on-site welding and casting operations increase the difficulty of construction organization and safety risks. In addition, existing technologies are at a low level in terms of assembly, modularization, and standardization. Most temporary support structures lack systematic assembly design, and component connections rely on on-site welding or temporary reinforcement measures. Construction quality is greatly affected by human factors, hindering rapid construction, quality control, and parallel operations at multiple work sites.

[0004] The shortcomings of traditional temporary support structures in terms of material consumption, construction energy consumption, and construction waste generation are becoming increasingly prominent, making it difficult to meet the comprehensive requirements of modern urban rail transit engineering for energy conservation, emission reduction, resource recycling, and construction industrialization.

[0005] Therefore, there is an urgent need for a construction method for temporary support structures that are suitable for subway station construction in confined spaces, are prefabricated, reusable, easy to construct, and safe and reliable, in order to overcome the problems of low reusability, low construction efficiency, poor site adaptability, and serious waste of resources in existing technologies. Summary of the Invention

[0006] The present invention aims to address the shortcomings of the prior art by providing a construction method for prefabricated temporary support structures for subway stations in confined spaces.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The construction method for prefabricated temporary support structures in subway stations located in confined spaces includes the following steps:

[0009] Step 1: Site preparation, traffic diversion and phased traffic management, measurement and positioning of diaphragm walls and intermediate columns;

[0010] Step 2: Close traffic on the construction side of the station and guide the traffic flow to the other side of the station. Connect the wall at the construction site on the construction side of the station and drill holes to the designed foundation layer at the predetermined intermediate column position. Insert the prefabricated perforated I-beam modules into the well holes in a precise vertical alignment manner to ensure sufficient embedding length during the excavation process to achieve load transfer and stability.

[0011] Step 3: By drilling, pour solidification material into the lower part of the perforated I-beam module until it reaches the level of the station floor slab to form an anti-uplift pile; after the grouting has solidified, backfill the upper part of the remaining perforated I-beam module above the platform ground with sand or controlled low-strength material to provide temporary lateral restraint and facilitate subsequent excavation;

[0012] Step 4: Excavate the construction side foundation pit in stages and layers according to the designed excavation sequence; while excavating layer by layer, install precast concrete retaining units between adjacent perforated I-beam modules; the precast concrete retaining unit is composed of a first precast concrete module and a second precast concrete module; one side of the first precast concrete module has a vertically penetrating groove interface, and the other side has multiple first limiting holes that match the reserved connection holes on the perforated I-beam module; the upper end face of the first precast concrete module has a female connector, and the lower end face has a male connector; one side of the second precast concrete module has a raised tenon structure that matches the groove interface, and the other side has multiple second limiting holes that match the reserved connection holes on the perforated I-beam module; the upper end face of the second precast concrete module has a female connector, and the lower end face has a male connector.

[0013] After excavating the first layer of soil to the first designed depth, the first layer of precast concrete retaining units is installed at the first layer depth: First, the first precast concrete module is assembled, and the first precast concrete module of the current layer is fixed to the corresponding perforated I-beam module by means of connecting bolts passing through the first limiting hole and the reserved connecting hole; then, the second precast concrete module is assembled, and the protruding tenon structure of the second precast concrete module is inserted into the groove interface of the first precast concrete module of the current layer to achieve lateral splicing, and the second precast concrete module of the current layer is fixed to the corresponding perforated I-beam module by means of connecting bolts passing through the second limiting hole and the reserved connecting hole.

[0014] Step 5: Continue excavating the second layer of soil to the designed depth. At this depth, install the second layer of precast concrete retaining units: Assemble the first precast concrete module of the second layer longitudinally by connecting the female connector to the male connector of the already installed first precast concrete module, and then fix the first precast concrete module of the current layer to the corresponding perforated I-beam module using connecting bolts. Next, assemble the second precast concrete module of the second layer, connecting the female connector to the male connector of the already installed second precast concrete module longitudinally. Simultaneously, the protruding tenon structure of the second precast concrete module is inserted into the grooved interface of the first precast concrete module of the current layer to achieve transverse splicing, and then fix the second precast concrete module of the current layer to the corresponding perforated I-beam module using connecting bolts.

[0015] Step Six: Repeat Step Five, and as the excavation depth increases, perform vertical docking and horizontal splicing three-dimensional assembly layer by layer downwards. The excavation-assembly cycle continues until the design depth is reached, forming a complete temporary support system.

[0016] Step 7: Construct a truss and install a reinforced concrete cover plate above the excavated construction side pit, redirect and restore traffic on that side, close traffic on the other side, and then construct a diaphragm wall on the other side.

[0017] Step 8: Excavate the other side of the foundation pit in layers, and as the excavation depth increases, dismantle the assembled precast concrete retaining units layer by layer, and recover the first and second precast concrete modules for subsequent reuse. The excavation-dismantling cycle is carried out until the other side of the foundation pit is excavated to the design depth.

[0018] Step Nine: Construct the internal structure of the station by adding steel cages, building formwork, and pouring reinforced concrete to transform the perforated I-beam modules at the top into composite intermediate columns, which serve as the permanent structure of the station.

[0019] Step 10: Complete the remaining finishing work at the station, dismantle temporary facilities, and fully restore traffic in the station area.

[0020] Specifically, in step three, the curing material is high-strength concrete or silicate cement.

[0021] Specifically, in step six, when the excavation depth exceeds 5m, temporary transverse horizontal steel supports are added.

[0022] Specifically, in step eight, during the excavation of the foundation pit, the overall deformation, ground settlement, and the status of the intermediate columns are continuously monitored.

[0023] Specifically, the female connector includes a female connector anchor bar, a female connector bolt fixing sleeve, and a spring; the female connector anchor bar and the female connector bolt fixing sleeve are embedded in the top of the first precast concrete module and the second precast concrete module, and the female connector anchor bar is axially fixed to the bottom of the outer wall of the female connector bolt fixing sleeve. The first precast concrete module and the second precast concrete module at the bottom of the female connector bolt fixing sleeve are provided with reserved grooves, and the spring is installed in the reserved grooves. The top opening of the female connector bolt fixing sleeve is stepped.

[0024] Specifically, the male connector includes a male connector anchor bar, a male connector bolt fixing structure, and a pin bolt; the male connector anchor bar and the male connector bolt fixing structure are embedded in the bottom of the first and second precast concrete modules, and the pin bolt is fixed to the center of the bottom of the male connector bolt fixing structure, while the male connector anchor bar is fixed to both sides of the male connector bolt fixing structure; when adjacent upper and lower first precast concrete modules and adjacent upper and lower second precast concrete modules are assembled, the pin bolt is inserted into the female connector bolt fixing sleeve and compresses the spring.

[0025] Specifically, the lateral dimension of a single first precast concrete module and second precast concrete module is smaller than the spacing between two adjacent perforated I-beam modules; the overall lateral dimension of the first precast concrete module and second precast concrete module after being laterally assembled matches the net distance between the webs of two adjacent perforated I-beam modules.

[0026] In particular, the perforated I-beam module has multiple sets of pre-reserved connection holes arranged vertically. The vertical position of each set of pre-reserved connection holes corresponds to the vertical height of the first and second precast concrete modules installed layer by layer, so as to realize the layered bolt connection between each layer of modules and the perforated I-beam module.

[0027] The beneficial effects of this invention are:

[0028] This invention achieves fully prefabricated construction of the support structure through the transverse tenon and mortise joint between the first and second prefabricated concrete modules, and the longitudinal connection of male and female joints between the upper and lower modules. No welding or cast-in-place work is required on-site, significantly shortening the construction cycle and reducing labor costs. Furthermore, the modular design simplifies construction organization and ensures quality control, making it particularly suitable for parallel operations at multiple work sites.

[0029] The lateral dimensions of a single first precast concrete module and a second precast concrete module are smaller than the spacing between two adjacent perforated I-beam modules, allowing for manual or small-scale mechanical assembly in confined spaces. This solves the problem of traditional support structures requiring large hoisting spaces and working surfaces, greatly improving site utilization efficiency. It is suitable for subway station construction in urban core areas, areas with complex pipelines, and limited space.

[0030] Both the first and second precast concrete modules can be completely recycled and dismantled layer by layer during the excavation of the opposite foundation pit, and reused in other projects, reducing the consumption of building materials and the generation of construction waste, which meets the requirements of sustainable development. The perforated I-beam modules serve as vertical load-bearing components during the temporary support stage, and can be transformed into composite intermediate columns by adding steel bars and pouring concrete during the permanent structure construction stage, becoming part of the station's permanent structure. This achieves an organic combination of temporary and permanent structures and reduces the overall project cost.

[0031] Multiple first and second precast concrete modules and perforated I-beam modules are connected by bolts to form a collaborative support system of "limiting-transferring-removable". The system has high overall rigidity and stability and can meet the strict requirements for deformation control in deep foundation pit construction.

[0032] All prefabricated modules are factory-customized and mass-produced, ensuring high dimensional accuracy and stable quality, thus avoiding the problem of on-site construction quality being greatly affected by human factors. The perforated I-beam modules have multiple sets of pre-drilled connection holes arranged vertically, precisely matching the module height to ensure accurate installation positions and reliable connections for each layer of modules. Attached Figure Description

[0033] Figure 1 This is a three-dimensional schematic diagram of the prefabricated temporary support structure of the present invention;

[0034] Figure 2 This is a schematic diagram of the first precast concrete module of the prefabricated temporary support structure of the present invention.

[0035] Figure 3 This is a schematic diagram of the second precast concrete module of the prefabricated temporary support structure of the present invention;

[0036] Figure 4 This is a schematic diagram of a perforated I-beam module of the prefabricated temporary support structure of the present invention;

[0037] Figure 5 This is a schematic diagram of the assembly of the first precast concrete module and the second precast concrete module of the prefabricated temporary support structure of the present invention.

[0038] Figure 6 This is a schematic diagram of the female joint structure of the prefabricated temporary support structure of the present invention;

[0039] Figure 7 This is a schematic diagram of the male joint structure of the prefabricated temporary support structure of the present invention;

[0040] Figure 8 This is a top view of the prefabricated temporary support structure of the present invention;

[0041] Figure 9This is a cross-sectional view of the prefabricated temporary support structure of the present invention;

[0042] Figure 10 This is a construction illustration of the prefabricated temporary support structure of the present invention as a temporary retaining structure for foundation pits. Figure 1 .

[0043] Figure 11 This is a construction illustration of the prefabricated temporary support structure of the present invention as a temporary retaining structure for foundation pits. Figure 2 .

[0044] In the diagram: 1-First precast concrete module; 10-Groove interface; 11-First limiting hole; 2-Second precast concrete module; 20-Protruding tenon structure; 21-Second limiting hole; 3-H-beam module with hole; 31-Reserved connection hole; 4-Female connector; 41-Female connector anchor bar; 42-Female connector bolt fixing sleeve; 43-Spring; 5-Male connector; 51-Male connector anchor bar; 52-Male connector bolt fixing structure; 53-Pin bolt; 6-Connecting bolt; 7-Curing material; 8-Soil; 9-Diaphragm wall;

[0045] The following will describe in detail, with reference to the accompanying drawings, embodiments of the present invention. Detailed Implementation

[0046] The present invention will be further described below with reference to embodiments:

[0047] like Figures 1-11 As shown, the construction method of prefabricated temporary support structure for subway station construction in confined spaces includes the following steps:

[0048] Step 1: Site preparation, traffic diversion and phased traffic management, measurement and positioning of diaphragm wall 9 and intermediate column.

[0049] Step 2: Close traffic on the construction side of the station and guide the traffic flow to the other side of the station. Construct the diaphragm wall 9 on the construction side of the station and drill holes to the designed foundation layer at the predetermined intermediate column position. Insert the prefabricated perforated I-beam module 3 into the well hole in a precise vertical alignment manner to ensure sufficient embedding length during the excavation process to achieve load transfer and stability. The perforated I-beam module 3 can be pre-reserved with connection holes 31 according to the actual needs of the site.

[0050] Step 3: By drilling, pour solidification material 7 into the lower part of the perforated I-beam module 3 until it reaches the horizontal position of the station floor slab, forming an anti-uplift pile (the grouting section serves as an anti-uplift pile and a temporary load-bearing component during excavation). After the grout has solidified, backfill the upper part of the remaining perforated I-beam module 3 above the platform ground with sand or controlled low-strength material to provide temporary lateral restraint and facilitate subsequent excavation. The solidification material 7 includes high-strength concrete, silicate cement, and other high-efficiency polymers.

[0051] Step 4: Excavate the construction side foundation pit in stages and layers according to the designed excavation sequence; while excavating layer by layer, install precast concrete retaining units between adjacent perforated I-beam modules 3; the precast concrete retaining unit is assembled from the first precast concrete module 1 and the second precast concrete module 2; one side of the first precast concrete module 1 is provided with a vertically penetrating groove interface 10, and the other side is provided with multiple first limiting holes 11 that match the reserved connection holes 31 on the perforated I-beam module 3; the upper end face of the first precast concrete module 1 is provided with a female connector 4, and the lower end face is provided with a male connector 5; one side of the second precast concrete module 2 is provided with a protruding tenon structure 20 that matches the groove interface 10, and the other side is provided with multiple second limiting holes 21 that match the reserved connection holes 31 on the perforated I-beam module 3; the upper end face of the second precast concrete module 2 is provided with a female connector 4, and the lower end face is provided with a male connector 5.

[0052] After excavating the first layer of soil to the designed depth, the first layer of precast concrete retaining units is installed at the first layer depth: First, the first precast concrete module 1 is assembled, and the first precast concrete module 1 of the current layer is fixed to the corresponding perforated I-beam module 3 by means of connecting bolts 6 passing through the first limiting hole 11 and the reserved connecting hole 31; then, the second precast concrete module 2 is assembled, and the protruding tenon structure 20 of the second precast concrete module 2 is inserted into the groove interface 10 of the first precast concrete module 1 of the current layer to achieve lateral splicing, and the second precast concrete module 2 of the current layer is fixed to the corresponding perforated I-beam module 3 by means of connecting bolts 6 passing through the second limiting hole 21 and the reserved connecting hole 31.

[0053] Specifically, the advantages of the modular design of precast concrete retaining units are: each module is small in size and light in weight, making it easy to transport and hoist in confined spaces; at the same time, by assembling two modules to form a complete retaining wall, the integrity of the structure is ensured, while the difficulty of prefabrication, transportation and installation of individual components is reduced.

[0054] Multiple first precast concrete modules 1 are continuously assembled longitudinally through the cooperation of female joints 4 and male joints 5 between adjacent modules. Multiple second precast concrete modules 2 are continuously assembled longitudinally through the cooperation of female joints 4 and male joints 5 between adjacent modules. Within the same horizontal layer, the first precast concrete modules 1 and the second precast concrete modules 2 are horizontally assembled through the cooperation of protruding tenon and mortise structure 20 and groove interface 10.

[0055] The grooved interface 10 extends vertically, allowing the raised tenon structure 20 of the second precast concrete module 2 to be inserted from any height on the side, eliminating the need for precise alignment during installation, significantly reducing installation difficulty and improving construction efficiency. The corresponding vertical arrangement of the female connector 4 and male connector 5 enables the module to extend vertically indefinitely, allowing for flexible adjustment of the number of assembly layers according to the depth of the foundation pit, adapting to the support needs of foundation pits at different depths. The engagement between the raised tenon structure 20 and the grooved interface 10 forms a "T-shaped" interlock, which not only enables rapid positioning for lateral assembly but also effectively transmits earth pressure, preventing relative displacement between modules and ensuring the integrity and flatness of the retaining wall surface; furthermore, the assembly creates a "self-locking" effect, preventing separation even under earth pressure, enhancing structural safety.

[0056] Furthermore, the female connector 4 includes a female connector anchor bar 41, a female connector bolt fixing sleeve 42, and a spring 43; the female connector anchor bar 41 and the female connector bolt fixing sleeve 42 are pre-embedded on the top of the first precast concrete module 1 and the second precast concrete module 2, and the female connector anchor bar 41 is axially fixed to the bottom of the outer wall of the female connector bolt fixing sleeve 42. The first precast concrete module 1 and the second precast concrete module 2 at the bottom of the female connector bolt fixing sleeve 42 are provided with reserved grooves, and the spring 43 is installed in the reserved grooves. The top opening of the female connector bolt fixing sleeve 42 is stepped.

[0057] The male connector 5 includes a male connector anchor bar 51, a male connector bolt fixing structure 52, and a pin bolt 53. The male connector anchor bar 51 and the male connector bolt fixing structure 52 are embedded in the bottom of the first precast concrete module 1 and the second precast concrete module 2, and the pin bolt 53 is fixed to the center of the bottom of the male connector bolt fixing structure 52. The male connector anchor bar 51 is fixed to both sides of the male connector bolt fixing structure 52. When adjacent upper and lower first precast concrete modules 1 and adjacent upper and lower second precast concrete modules 2 are assembled, the pin bolt 53 is inserted into the female connector bolt fixing sleeve 42 and compresses the spring 43.

[0058] During module installation, spring 43 is compressed, generating preload to ensure a tight connection between the upper and lower modules, preventing loosening due to manufacturing errors or construction disturbances. During module removal, the elasticity of spring 43 assists in pushing the pin bolt 53, allowing easy separation of the male and female connectors, solving the problems of traditional plug-in structures being prone to jamming and difficult to remove. The stepped opening design of the female connector bolt fixing sleeve 42 guides the accurate insertion of the pin bolt 53 and also acts as a limit after connection, preventing lateral swaying. The pre-embedded anchor bars 41 of the female connector and 51 of the male connector ensure reliable anchoring between the connector and the concrete body, enabling the joint to withstand greater tensile and shear forces, meeting the stress requirements of deep foundation pit support.

[0059] The lateral dimension of each individual first precast concrete module 1 and second precast concrete module 2 is smaller than the spacing between two adjacent perforated I-beam modules 3; the overall lateral dimension of the first precast concrete module 1 and second precast concrete module 2 after lateral assembly matches the clear distance between the webs of two adjacent perforated I-beam modules 3. The individual module size being smaller than the I-beam spacing means that each module can be independently hoisted into its installation position from between the I-beams without requiring additional lateral movement space, which is particularly important in confined spaces with limited hoisting space. The matching of the assembled dimensions with the clear distance ensures that after installation, the first precast concrete module 1 and second precast concrete module 2 fit tightly against the perforated I-beam modules 3 on both sides, without any excess gaps, preventing soil loss from the gaps, and ensuring accurate alignment of the connecting bolts 6.

[0060] Multiple sets of pre-drilled connection holes 31 are arranged vertically on the perforated I-beam module 3. The vertical position of each set of pre-drilled connection holes 31 corresponds to the vertical height of the first precast concrete module 1 and the second precast concrete module 2 installed layer by layer, so as to realize the layered bolt connection between each layer of modules and the perforated I-beam module 3. The I-beam, as an intermediate column, has both bending stiffness and shear strength, and can withstand the soil pressure and groundwater pressure during the excavation of the foundation pit. It also serves as a lateral support point for the first precast concrete module 1 and the second precast concrete module 2. The multiple sets of pre-drilled connection holes 31, with the vertical position of each set of holes corresponding to the vertical height of the first precast concrete module 1 and the second precast concrete module 2 installed layer by layer, have the advantage of this layered corresponding design: each layer of module has its own independent connection point, the force path is clear, and stress concentration is avoided when the load is transferred downward.

[0061] The horizontal mortise and tenon joints, longitudinal male and female joints, and bolt connections constitute a multi-dimensional connection system of "point (bolt) - line (male and female joints) - surface (mortise and tenon joints)," resulting in good structural integrity and uniform stress distribution. All components are prefabricated in the factory, requiring only hoisting and bolt tightening on-site, leading to fast construction speed, controllable quality, and conforming to the development trend of industrialized construction. All connections are mechanical, eliminating the need for welding or cast-in-place casting, resulting in high reusability and being economical and environmentally friendly. The module size can be adjusted according to project needs, and the connection hole positions can be flexibly set according to the depth of the foundation pit, enabling it to adapt to subway station foundation pit projects of different scales and geological conditions.

[0062] Step 5: Continue excavating the second layer of soil 8 to the designed depth of the second layer, and then install the second layer of precast concrete retaining units at the second layer depth: continue assembling the first precast concrete module 1 of the second layer, and longitudinally assemble it with the male connector 5 of the already installed first precast concrete module 1 through the female connector 4, and fix the first precast concrete module 1 of the current layer to the corresponding perforated I-beam module 3 through the connecting bolts 6; then assemble the second precast concrete module 2 of the second layer, and longitudinally assemble it with the male connector 5 of the already installed second precast concrete module 2 through the female connector 4. At the same time, the protruding tenon structure 20 of the second precast concrete module 2 is inserted into the groove interface 10 of the first precast concrete module 1 of the current layer to achieve lateral splicing, and fix the second precast concrete module 2 of the current layer to the corresponding perforated I-beam module 3 through the connecting bolts 6;

[0063] Step Six: Repeat Step Five, and as the excavation depth increases, perform vertical docking and horizontal splicing of the three-dimensional assembly layer by layer downwards. The excavation-assembly cycle continues until the design depth is reached, forming a complete temporary support system. Furthermore, an automated monitoring system can be used to collect data such as ground settlement around the foundation pit, horizontal displacement of the diaphragm wall 9, and verticality of the intermediate columns in real time. Construction parameters can be dynamically adjusted based on the monitoring results. When the excavation depth exceeds 5m, temporary horizontal steel supports can be added to provide horizontal top support reaction force, balance the soil pressure behind the wall, control the horizontal displacement of the diaphragm wall 9, and prevent the foundation pit from undergoing excessive deformation or instability due to increased depth.

[0064] Step 7: Construct a truss and install a reinforced concrete cover plate above the excavated construction side pit, redirect and restore traffic on that side, close traffic on the other side, and then construct a diaphragm wall 9 on the other side.

[0065] Step 8: Excavate the other side of the foundation pit in layers, and as the excavation depth increases, dismantle the assembled precast concrete retaining units layer by layer, and recover the first precast concrete module 1 and the second precast concrete module 2 for subsequent reuse. The excavation-dismantling cycle is carried out until the other side of the foundation pit is excavated to the design depth. During the excavation of the foundation pit, the overall deformation, ground settlement and the status of the intermediate columns are continuously monitored.

[0066] Step Nine: Construct the internal structure of the station. By adding steel cages, building formwork, and pouring reinforced concrete, the upper perforated I-beam module 3 is transformed into a composite intermediate column as the permanent structure of the station.

[0067] Step 10: Complete the remaining finishing work at the station, dismantle temporary facilities, and fully restore traffic in the station area.

[0068] During construction, the present invention involves excavating the foundation pit in layers on one side and assembling the support modules layer by layer, while excavating the foundation pit in layers on the other side and dismantling and recycling the modules layer by layer. This invention achieves fully prefabricated construction and modular recycling of the support structure, and has the advantages of convenient construction, adaptability to small sites, reusability, and environmental protection. It is suitable for deep foundation pit projects under limited conditions such as subway stations in urban core areas.

[0069] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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.

[0070] Furthermore, the terms "first" and "second" 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 as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0071] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0072] The present invention has been described above by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or direct application to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A construction method for prefabricated temporary support structures in subway stations located in confined spaces, characterized in that: Includes the following steps: Step 1: Site preparation, traffic diversion and phased traffic management, measurement and positioning of diaphragm wall (9) and intermediate column; Step 2: Close traffic on the construction side of the station and guide the traffic flow to the other side of the station. Connect the wall (9) on the construction side of the station and drill holes to the designed foundation layer at the predetermined intermediate column position. Insert the prefabricated perforated I-beam module (3) into the well hole in a precise vertical alignment manner to ensure sufficient embedding length during the excavation process to achieve load transfer and stability. Step 3: By drilling, pour solidification material (7) into the lower part of the perforated I-beam module (3) until it reaches the horizontal position of the station floor slab to form an anti-uplift pile; after the grouting is solidified, backfill the upper part of the remaining perforated I-beam module (3) above the platform ground with sand or controlled low-strength material to provide temporary lateral restraint and facilitate subsequent excavation; wherein, the solidification material (7) is high-strength concrete or silicate cement; Step 4: Excavate the construction side foundation pit in stages and layers according to the design excavation sequence; while excavating layer by layer, install precast concrete retaining units between adjacent perforated I-beam modules (3); the precast concrete retaining unit is composed of a first precast concrete module (1) and a second precast concrete module (2); one side of the first precast concrete module (1) is provided with a groove interface (10) that runs vertically through, and the other side is provided with multiple first limiting holes (11) that match the reserved connection holes (31) on the perforated I-beam module (3); the upper end face of the first precast concrete module (1) is provided with a female connector (4), and the lower end face is provided with a male connector (5); one side of the second precast concrete module (2) is provided with a protruding tenon structure (20) that matches the groove interface (10), and the other side is provided with multiple second limiting holes (21) that match the reserved connection holes (31) on the perforated I-beam module (3); the upper end face of the second precast concrete module (2) is provided with a female connector (4), and the lower end face is provided with a male connector (5); After excavating the first layer of soil (8) to the first layer design depth, the first layer of precast concrete retaining unit is installed at the first layer depth: first, the first precast concrete module (1) is assembled, and the first precast concrete module (1) of the current layer is fixed with the corresponding perforated I-beam module (3) by passing the connecting bolt (6) through the first limiting hole (11) and the reserved connecting hole (31); then, the second precast concrete module (2) is assembled, and the protruding tenon structure (20) of the second precast concrete module (2) is inserted into the groove interface (10) of the first precast concrete module (1) of the current layer to achieve horizontal splicing, and the second precast concrete module (2) of the current layer is fixed with the corresponding perforated I-beam module (3) by passing the connecting bolt (6) through the second limiting hole (21) and the reserved connecting hole (31); Step 5: Continue excavating the second layer of soil (8) to the designed depth of the second layer, and then install the second layer of precast concrete retaining unit at the depth of the second layer: continue to assemble the first precast concrete module (1) of the second layer, and assemble it longitudinally with the male connector (5) of the already installed first precast concrete module (1) through the female connector (4), and fix the first precast concrete module (1) of the current layer with the corresponding perforated I-beam module (3) through the connecting bolts (6); then assemble the second precast concrete module (2) of the second layer, and assemble it longitudinally with the male connector (5) of the already installed second precast concrete module (2) through the female connector (4). At the same time, the protruding tenon structure (20) of the second precast concrete module (2) is inserted into the groove interface (10) of the first precast concrete module (1) of the current layer to achieve transverse splicing, and fix the second precast concrete module (2) of the current layer with the corresponding perforated I-beam module (3) through the connecting bolts (6); Step Six: Repeat Step Five, and as the excavation depth increases, perform vertical docking and horizontal splicing three-dimensional assembly layer by layer downwards. The excavation-assembly cycle continues until the design depth is reached, forming a complete temporary support system. Step 7: Build a truss and install a reinforced concrete cover plate above the excavated construction side pit, redirect and restore traffic on that side, close traffic on the other side, and then build a diaphragm wall (9) on the other side. Step 8: Excavate the foundation pit on the other side in layers, and as the excavation depth increases, dismantle the assembled precast concrete retaining units layer by layer, and recover the first precast concrete module (1) and the second precast concrete module (2) for subsequent reuse. The excavation-dismantling cycle is carried out until the foundation pit on the other side is excavated to the design depth. Step 9: Construct the internal structure of the station. By adding steel cages, building formwork and pouring reinforced concrete, the upper perforated I-beam module (3) is transformed into a composite intermediate column as the permanent structure of the station. Step 10: Complete the remaining finishing work at the station, dismantle temporary facilities, and fully restore traffic in the station area.

2. The construction method for prefabricated temporary support structures in subway stations in confined spaces according to claim 1, characterized in that, In step six, when the excavation depth exceeds 5m, temporary transverse horizontal steel supports are added.

3. The construction method for prefabricated temporary support structures in subway stations in confined spaces according to claim 1, characterized in that, In step eight, during the excavation of the foundation pit, the overall deformation, ground settlement, and the status of the intermediate columns are continuously monitored.

4. The construction method for prefabricated temporary support structures for subway stations in confined spaces according to claim 1, characterized in that, The female connector (4) includes a female connector anchor bar (41), a female connector bolt fixing sleeve (42), and a spring (43). The female connector anchor bar (41) and the female connector bolt fixing sleeve (42) are embedded in the top of the first precast concrete module (1) and the second precast concrete module (2), and the female connector anchor bar (41) is axially fixed to the bottom of the outer wall of the female connector bolt fixing sleeve (42). The first precast concrete module (1) and the second precast concrete module (2) at the bottom of the female connector bolt fixing sleeve (42) are provided with reserved grooves, and the spring (43) is installed in the reserved grooves. The top opening of the female connector bolt fixing sleeve (42) is stepped.

5. The construction method for prefabricated temporary support structures for subway stations in confined spaces according to claim 1, characterized in that, The male connector (5) includes a male connector anchor bar (51), a male connector bolt fixing structure (52), and a pin bolt (53). The male connector anchor bar (51) and the male connector bolt fixing structure (52) are embedded in the bottom of the first precast concrete module (1) and the second precast concrete module (2), and the pin bolt (53) is fixed to the center of the bottom of the male connector bolt fixing structure (52). The male connector anchor bar (51) is fixed to both sides of the male connector bolt fixing structure (52). When the adjacent upper and lower first precast concrete modules (1) and the adjacent upper and lower second precast concrete modules (2) are assembled, the pin bolt (53) is inserted into the female connector bolt fixing sleeve (42) and the spring (43) is compressed.

6. The construction method for prefabricated temporary support structures in subway stations in confined spaces according to claim 1, characterized in that, The lateral dimension of a single first precast concrete module (1) and second precast concrete module (2) is smaller than the spacing between two adjacent perforated I-beam modules (3); the overall lateral dimension of the first precast concrete module (1) and second precast concrete module (2) after being laterally assembled matches the net distance between the webs of two adjacent perforated I-beam modules (3).

7. The construction method for prefabricated temporary support structures for subway stations in confined spaces according to claim 1, characterized in that, The pre-reserved connection holes (31) on the perforated I-beam module (3) are arranged in multiple sets along the vertical direction. The vertical position of each set of pre-reserved connection holes (31) corresponds to the vertical height of the first precast concrete module (1) and the second precast concrete module (2) installed layer by layer, so as to realize the layered bolt connection between each layer of modules and the perforated I-beam module (3).

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