Underground excavation station flat top structure rail top air duct structure and construction method

Abstract

The invention belongs to the technical field of building construction, and particularly relates to an underground excavation station flat top structure rail top air duct structure and a construction method. The rail top air duct comprises an underground excavation section bottom plate, a side wall, a top plate, an air duct lower connecting wall and an air duct flat plate, the underground excavation section bottom plate is connected with the side wall, the side wall is vertically arranged under the top plate, the air duct lower connecting wall is arranged under the top plate, and the air duct flat plate is arranged under the top plate. The side wall, the air duct lower connecting wall and the top plate are connected through steel bars and are poured into an integrated structure, and the air duct flat plate and the air duct lower connecting wall are welded together. The top plate and the air duct lower connecting wall are integrally poured, the situation that the air duct, the air duct lower connecting wall and the top plate cannot be densely poured in subsequent pouring is avoided, the air duct and the top plate are basically connected through steel bars, and effective welding of steel bars of the lower connecting wall and the air duct straight section during subsequent pouring of the air duct straight section is guaranteed; therefore, the air duct lower connecting wall and the air duct flat plate are connected into a reliable whole.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a track top air duct structure of a flat-top structure of a concealed excavation station and a construction method. Background Art

[0002] The underground excavation part of the project mainly passes through silty clay and silty sand and silt soil layers. The strata are fluid and plastic, extremely sensitive to excavation disturbances, and difficult to control settlement. Due to the presence of silty soil layers in the upper part, the water permeability is weak and there is pressurized water in the silty sand and silt soil layers, resulting in poor stability of the excavation face. Therefore, a variety of different methods are needed to improve the foundation. Horizontal MJS construction method piles, as a form of foundation reinforcement, are often used in the construction of underground excavation sections. However, due to the complex foundation structure in the city, unknown obstacles are often encountered during the horizontal MJS construction method pile boring process, which brings many uncertainties to the construction, among which the breakage of the drill rod is the most common problem.

[0003] Station structure construction is a relatively conventional construction process, and the site adopts cast-in-place method and prefabricated assembly method. As a part of the station structure, the track top air duct is mainly used for the ventilation and exhaust of the station. The conventional station air duct structure is placed under the middle plate of the station track area. The casting can be done by first casting the track top air duct and then constructing the middle plate, or first constructing the middle plate, reserving steel bars and casting holes on the middle plate, and then casting later. However, because the flat-top frame structure of the newly built station is located below the top plate of the completed station structure, its concrete pouring cannot be cast from above or through the reserved holes in the middle plate. The whole is cast after pouring. Since the casting holes can only be located below the cast structural plate, the concrete cannot be completely attached to the bottom of the structural plate during the pouring process. There is a gap where concrete cannot be poured at the connection between the air duct and the structural plate. In addition, the air duct is located above the train, which poses a great safety and quality hazard. At the same time, it also fails to achieve the function of guiding ventilation and exhaust.

[0004] The Chinese patent announcement is CN111501830A, which discloses a rail-top air duct structure of an open-cut subway station and a sequential construction method thereof. The main structure of the subway station includes a bottom plate, side walls cast on the bottom plate, and a middle floor plate formed on the inner side of the side wall. The rail-top air duct structure includes: a duct base plate, which is arranged between the middle floor plate and the bottom plate along the length direction of the intersection of the middle floor plate and the side wall, the duct base plate has a first side away from the side wall and a second side close to the side wall, and the second side of the duct base plate is connected to the side wall; and a duct side plate, which is connected to the first side of the duct base plate and the bottom of the middle floor plate. The duct base plate, the duct side plate, the side wall and the middle floor plate enclose the rail-top air duct of the subway station. During the pouring process, the concrete cannot be completely attached to the bottom of the structural plate, and there is a gap where the air duct and the structural plate are connected, where concrete cannot be poured. In addition, the air duct is located above the train, which poses a great safety and quality hazard, and also fails to achieve the function of guiding ventilation and exhaust. Therefore, it is urgent for those skilled in the art to solve the above technical problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is that in the above-mentioned prior art, during the pouring process, the concrete cannot be completely tightly attached to the bottom of the structural plate, and there is a gap where concrete cannot be poured at the connection between the air duct and the structural plate. In addition, the air duct is located above the train, which poses a great safety and quality hazard, and also fails to achieve the function of guiding ventilation and exhaust.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A track-top air duct structure of a flat-top structure of a concealed excavation station comprises a concealed excavation section bottom plate, side walls, a top plate, a duct lower connecting wall and a duct flat plate, wherein the concealed excavation section bottom plate is connected to the side walls, the side walls are vertically arranged directly below the top plate, the duct lower connecting wall is arranged below the top plate, the side walls, the duct lower connecting wall and the top plate are connected by steel bars and cast into an integrated structure, and the duct flat plate is welded to the duct lower connecting wall.

[0007] By adopting the above technical solution, the side wall, the lower connecting wall of the duct and the top plate are connected by steel bars and cast into an integrated structure, which greatly enhances the integrity and stability of the entire structure. This not only improves the bearing capacity of the structure, but also reduces the risk of relative displacement between different parts. The bottom of the connecting steel bar is anchored into the upper surface of the duct plate, and the top and top plate steel bars are spot welded and fixed. The welding connection end is reserved for subsequent operations, ensuring the quality and reliability of the connection. At the connection between the lower connecting wall of the duct and the duct plate, special attention is paid to the close combination of the formwork to ensure that there will be no leakage during concrete pouring, thereby improving the construction quality. The duct plate and the lower connecting wall of the duct are welded together to form a complete ventilation and exhaust system.

[0008] Furthermore, connecting steel bars are arranged on the side wall, the connecting steel bars are connected by straight threaded sleeves, and the connecting steel bars are "L" shaped.

[0009] By adopting the above technical solution, the straight thread sleeve connection provides extremely high mechanical properties and reliable connection strength. Compared with traditional binding or welding connections, the straight thread sleeve can better transfer stress and reduce stress concentration at the joint, thereby improving the overall stability and durability of the structure. By processing the connecting steel bars into an "L" shape, it not only enhances the bond strength between the connecting steel bars and the concrete, but also provides convenient conditions for the subsequent welding of the duct plate and the lower wall of the duct. The straight thread sleeve connection can quickly complete the docking of the steel bars without the need for complex welding equipment and processes, greatly shortening the construction time and improving the construction efficiency. The straight thread sleeve connection requires higher precision, which makes the steel bar connection more reliable and reduces the quality problems caused by manual operation errors. Each joint can maintain consistent connection quality, avoiding the uneven phenomenon that may occur in traditional binding or welding, and ensuring the consistency and stability of the entire structure. The "L"-shaped design of the connecting steel bars takes into account the convenience of template installation and removal. The bottom steel bar reserves a welding connection end to facilitate the subsequent welding of the duct plate steel bars and ensure the effective connection between the lower wall of the duct and the duct plate.

[0010] Furthermore, reinforcing steel bars are arranged inside the top plate, and the reinforcing steel bars are welded together with the connecting steel bars.

[0011] By adopting the above technical solution, a continuous integral structure is formed by welding the reinforcing steel bars inside the top plate to the connecting steel bars. This not only enhances the strength of the top plate itself, but also improves the integrity and stability of the entire station structure. The welded connection allows the stress to be more evenly distributed throughout the structure, reducing the risk of local stress concentration, thereby improving the safety and durability of the structure. The setting of the reinforcing steel bars significantly improves the bending and shearing properties of the top plate, enabling it to withstand greater loads, which is particularly important for structures such as underground excavation stations that need to withstand traffic and other dynamic loads above. The welded reinforcing steel bars enhance the rigidity of the top plate, effectively resist deformation caused by external loads, and ensure the long-term stability and functionality of the structure. The welded reinforcing steel bars and connecting steel bars form a strong constraint system, which enhances the ductility and energy absorption capacity of the structure, and helps to reduce structural damage in extreme situations such as earthquakes.

[0012] Furthermore, the bottom of the connecting steel bar is anchored into the upper surface of the air duct flat plate, and the top of the connecting steel bar is fixed to the top plate steel bar by spot welding.

[0013] By adopting the above technical scheme, the connecting steel bars extend from the duct slab to the top plate, forming a continuous vertical connection system, which enhances the integrity and stability of the entire structure. The bottom anchoring and top spot welding fixation ensure the close connection between the duct slab, the duct lower wall, the side wall and the top plate, forming a solid overall structure. The bottom of the connecting steel bars is anchored into the duct slab, which increases the tensile strength between the duct slab and the duct lower wall and prevents separation between the two. The top is spot welded to the top plate steel bars, which enhances the shear resistance between the top plate and the duct lower wall and improves the stability of the structure when subjected to horizontal loads. As a vertical component, the connecting steel bars can effectively transfer the load on the top plate to the duct slab, avoiding local stress concentration and making the stress more evenly distributed throughout the structure. Especially under the action of train running or other dynamic loads, the connecting steel bars can effectively disperse these loads to the duct slab and the underlying structure below it, reducing the risk of structural deformation.

[0014] The present invention also includes a construction method for a track top air duct structure of a dark excavation station flat roof structure, which is used to install the track top air duct structure of a dark excavation station flat roof structure, and includes the following steps: Step 1: Construct the bottom plate of the dark excavation section and set up the frame to tie the steel bars of the side wall top plate; Step 2: Tie up the steel bars for connecting the wall under the air duct and install the formwork; Step 3: Concrete pouring of side walls, top slab and lower connecting wall of the dark excavation section; Step 4: Remove the formwork and straighten the steel bars of the duct slab; Step 5: Tie steel bars for the duct slab, install formwork, and pour concrete; Step 6: Remove the duct plate template.

[0015] Furthermore, in step 1 and step 2, a dark excavation section reinforcement body is set on the dark excavation section, and a preliminary supporting structure of the dark excavation section is set inside the dark excavation section reinforcement body. Then, the bottom plate steel bars of the dark excavation section structure are tied, and side wall connecting steel bars are reserved. After the steel bars are tied, concrete is poured. Then, the side wall and top plate support system is set up. The support system serves as an operating platform for steel bar tying before the formwork is installed. During the tying process, side wall connecting steel bars are reserved. The connecting steel bar joints are staggered by 50% in the same section to disperse stress and enhance the connection strength.

[0016] By adopting the above technical solution and selecting appropriate reinforcement methods (such as MJS method piles, micro piles or rotary jet piles, etc.), reinforcement bodies are set on the dark excavation section, which effectively improves the bearing capacity and stability of the soft soil stratum and reduces the risk of settlement. The reinforcement bodies can cope with geological conditions such as crossing silty clay, silt sand and silty soil strata, ensuring the safety and feasibility of construction. A preliminary support structure (such as steel arch frame, reinforced concrete temporary support or shotcrete, etc.) is set inside the reinforcement body to provide necessary initial support for subsequent construction and prevent possible collapse and displacement during excavation. The preliminary support structure enhances safety during construction, especially under complex geological conditions, and provides workers with a safer working environment. The reinforcement body and preliminary support structure are The setting of the support structure provides a solid foundation for the subsequent bottom plate reinforcement binding, concrete pouring and support system construction, simplifies the construction process and improves the overall construction efficiency. The high-quality reinforcement and support reduces the possibility of rework due to geological problems, saves time and cost. The setting of the reinforcement body and the preliminary support structure provides an accurate reference surface for subsequent construction, ensuring the accurate position of each structural component. The design of the reinforcement body and the support structure takes into account the stress distribution, reduces local stress concentration, and ensures the consistency and reliability of construction quality. When binding the bottom plate reinforcement of the dark excavation section structure, side wall connecting steel bars are reserved. These connecting steel bars adopt an "L" shape design, and the joints are staggered by 50% in the same section to disperse stress and enhance the connection strength.

[0017] Furthermore, in step 3 and step 4, a total station is used to accurately mark the position of the lower wall of the duct on the top plate steel bars that have been tied as the layout position. The upper end of the connecting steel bar should be anchored into the steel skeleton of the top plate and spot welded to the steel bars of the top plate to ensure a firm connection. The connecting steel bar needs to be located at the elevation of the upper surface of the duct slab to ensure that the duct slab steel bars can be effectively welded to it. In order to facilitate the installation and removal of the template, the bottom of the connecting steel bar needs to be placed in the template, and a welding connection end is reserved to facilitate subsequent construction operations. After all the reserved steel bar binding work is completed, the template is installed, first the side wall template is installed, and then the top plate template. For the position of the lower wall of the duct, space should be reserved when the template is installed. After the top plate template is installed and reinforced, the lower wall template of the duct is installed to ensure the integrity of the lower wall of the duct and the top plate during concrete pouring. A plumb bob is used to check the verticality of the lower wall template of the duct to ensure its accurate position, thereby ensuring the geometric accuracy of the duct structure.

[0018] Furthermore, in step 5 and step 6, after the support system is stabilized, the duct slab formwork is installed. The joints between the duct formworks need to be handled tightly to prevent leakage during concrete pouring. For the duct formworks at the connection between the lower wall of the duct and the duct slab, special attention should be paid to ensure that they are tightly combined to ensure the quality of concrete pouring. After the duct formworks are installed, the duct slab steel bars are tied. The duct slab steel bars are welded to the adjusted connecting steel bars of the lower wall of the duct. During the tying process, a support frame is used to ensure that the steel bars are correctly positioned before pouring to avoid displacement. After the steel bars are tied, a ground pump is used for concrete pouring. The pouring speed needs to be controlled during pouring to avoid deformation of the formwork or uneven concrete caused by too fast a speed. When a ground pump is used for pouring, the side walls are Set up multiple rows of pouring holes, and control the pouring speed of the side wall in layers to no more than 3 meters per hour. After pouring to the height of the bottom row of pouring holes, gradually move to the upper layer of pouring holes, and close the lower layer of pouring holes. When pouring the top plate, since the lower connecting wall of the air duct is lower than the top plate, the concrete will naturally flow into the lower connecting wall of the air duct. The pouring speed should be controlled at no more than 2 meters per hour to ensure that the concrete can evenly fill the space in the formwork, and monitor the pouring height and fluidity through the observation port. After pouring, properly vibrate and level the concrete surface to ensure the quality of the concrete, and promptly cover it with curing materials for moisturizing maintenance; first remove the top plate formwork, then remove the side wall formwork, and finally remove the bracket. After the formwork is removed, clean up the construction site, sort out and recycle the formwork and bracket to prepare for subsequent construction.

[0019] The present invention has the following beneficial effects: 1. The present invention forms a continuous integral structure by connecting the side wall, the lower connecting wall of the air duct and the top plate through steel bars and casting them into an integrated structure, and anchoring the bottom of the connecting steel bars into the upper surface of the air duct flat plate, and fixing the top and top plate steel bars by spot welding, thereby enhancing the integrity and stability of the entire station structure, not only improving the bearing capacity of the structure, but also reducing the risk of relative displacement between different parts. Under complex geological conditions (such as passing through silty silty clay, silty sand and silty soil layers), the setting of the reinforcement body and the preliminary support structure effectively improves the foundation conditions and ensures the safety and feasibility of the construction; 2 The present invention provides extremely high mechanical properties and reliable connection strength by using a straight threaded sleeve to connect the "L"-shaped connecting steel bars. Special attention is paid to the close combination of the template at the connection between the wall under the duct and the duct flat plate to prevent leakage during concrete pouring. The connecting steel bar joints are staggered by 50% in the same section to disperse the stress and enhance the connection strength. The total station is used for line laying and positioning to ensure that the positions of each component are accurate and correct, which significantly improves the construction quality. At the same time, by setting up reinforcement bodies and preliminary support structures, a safer working environment is provided for workers and construction risks are reduced; 3. The present invention simplifies the construction process, improves construction efficiency, and reduces subsequent maintenance costs through a series of innovative designs. The setting of the reinforcement body and the preliminary support structure provides a solid foundation for the subsequent bottom plate reinforcement binding, concrete pouring, and support system construction, simplifies the construction process, and improves the overall construction efficiency. High-quality reinforcement and support reduce the possibility of rework due to geological problems, saving time and cost. The welded reinforcement steel bars and connecting steel bars form a strong constraint system, which enhances the ductility and energy absorption capacity of the structure, and helps to reduce structural damage in extreme situations such as earthquakes. After pouring, the concrete surface is properly vibrated and leveled, and covered with maintenance materials in time for moisturizing maintenance, which ensures the quality of the concrete, extends the service life of the structure, and reduces the need for long-term maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the installation structure of the present invention; Figure 3 This is a schematic diagram of the erection of the operating platform and the tying of the steel bars of the side wall top plate of the present invention; Figure 4 This is a schematic diagram of the steel bar binding of the lower wall of the air duct of the present invention; Figure 5 This is a schematic diagram of the installation of the side wall, top plate, and lower wall template of the air duct of the present invention; Figure 6 It is a schematic diagram of concrete pouring of the present invention; Figure 7 This is a schematic diagram of steel bar binding and pouring of the straight section of the air duct of the present invention; Figure 8 This is a schematic diagram of the completion of the integral casting of the structure of the present invention.

[0021] Among them, 1-soil layer; 2-reinforcement body; 3-primary supporting structure; 4-bottom plate of dark excavation section; 5-side wall; 6-top plate; 7-lower connecting wall of air duct; 8-air duct flat plate. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

[0023] In the description of the present invention, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second" and the like do not indicate the importance of the components, and therefore cannot be understood as limiting the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the scope of protection of the present invention.

[0024] like Figure 1 and Figure 2 As shown, a track-top air duct structure of a flat-top structure of a dark-cut station includes a dark-cut section bottom plate 4, a side wall 5, a top plate 6, a lower connecting wall 7 of the air duct, and an air duct flat plate 8. The dark-cut section bottom plate 4 is the foundation of the entire station and is connected to the side wall 5 through steel bars; the side wall 5 is vertically arranged directly below the top plate 6, and is connected to the top plate 6 and the lower connecting wall 7 of the air duct through steel bars, and is cast into an integrated structure, ensuring the tight connection and overall stability between the components. The top plate 6 covers the top of the station and is connected to the side wall 5 and the lower connecting wall 7 of the air duct through steel bars to form a solid overall structure; the lower connecting wall 7 of the air duct is located below the top plate 6, and is also connected to the top plate 6 and the side wall 5 through steel bars and cast into an integrated structure, enhancing the stability of the structure. The air duct flat plate 8 constitutes the horizontal part of the track-top air duct and is directly welded to the lower connecting wall 7 of the air duct, ensuring the integrity and air tightness of the air duct structure, and also facilitating subsequent construction operations. The side wall 5 is provided with connecting steel bars of "L" shape design. These connecting steel bars are connected by straight threaded sleeves to enhance the connection strength and reliability. The joints of the connecting steel bars are staggered by 50% in the same section to disperse stress and enhance the connection strength. Reinforcing steel bars are arranged inside the top plate 6. These reinforcing steel bars are welded together with the connecting steel bars to form a continuous integral structure, which enhances the strength and bearing capacity of the top plate itself. In terms of specific connection details, the bottom of the connecting steel bar is anchored into the upper surface of the air duct plate 8, and a welding connection end is reserved to facilitate the subsequent welding of the air duct plate steel bars; and the top of the connecting steel bar is spot welded to the top plate 6 steel bar to ensure a firm connection while reducing stress concentration. This design not only enhances the integrity and stability of the structure, but also improves the construction quality and safety. It is particularly suitable for complex engineering environments such as underground stations. like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the present invention also includes a construction method for a track top air duct structure of a dark excavation station flat roof structure, comprising the following steps: step 1: constructing a dark excavation section bottom plate 4 and setting up a frame to tie up the side wall 5 top plate 6 steel bars; Step 2: Tie up the steel bars of the lower wall of the air duct and install the formwork; Step 3: Concrete pouring of the side wall 5, top plate 6 and lower connecting wall of the dark excavation section; Step 4: Remove the formwork and straighten the steel bars of the duct slab 8; Step 5: Tie steel bars of air duct slab 8, install formwork, and pour concrete; Step 6: Remove the template of duct plate 8.

[0025] First, set a reinforcement body 2 on the dark excavation section, and select appropriate reinforcement methods such as MJS method piles, micro piles or rotary jet piles to improve foundation conditions and enhance bearing capacity and stability. Next, set a preliminary support structure 3 on the inside of the reinforcement body to provide necessary initial support for subsequent construction and prevent collapse and displacement that may occur during excavation. Subsequently, tie the steel bars of the bottom plate 4 of the dark excavation section structure, and reserve side wall 5 connecting steel bars. These connecting steel bars adopt an "L"-shaped design, and the joints are staggered by 50% in the same section to disperse stress and enhance connection strength. After the steel bars are tied, concrete is poured to form a solid bottom plate structure. Then set up the side wall 5 and top plate 6 support system, which is used as an operating platform for steel bar tying before the template is installed; Next, use a total station to accurately mark the position of the lower connecting wall 7 of the duct on the top plate 6 steel bars that have been tied as the layout position. Tie the steel bars of the lower connecting wall 7 of the duct, and ensure that the upper end of the connecting steel bars is anchored into the steel skeleton of the top plate 6, and spot welded to the top plate 6 steel bars to ensure a firm connection. The connecting steel bars must be located at the elevation of the upper surface of the duct slab 8 to ensure that the steel bars of the duct slab 8 can be effectively welded to it. In order to facilitate the installation and removal of the formwork, the bottom of the connecting steel bars needs to be placed inside the formwork, and a welding connection end is reserved to facilitate subsequent construction operations. After all the reserved steel bar tying work is completed, start installing the formwork, first install the side wall 5 formwork, and then the top plate 6 formwork. For the position of the lower connecting wall 7 of the duct, space should be reserved when the formwork is installed, and the lower connecting wall 7 formwork of the duct should be installed after the top plate 6 formwork is installed and reinforced, so as to ensure the integrity of the lower connecting wall 7 of the duct and the top plate 6 during concrete pouring. Use a plumb bob to check the verticality of the template of the lower connecting wall 7 of the duct to ensure its accurate position, thereby ensuring the geometric accuracy of the duct structure; Subsequently, concrete is poured on the side walls 5, top plate 6 and lower connecting wall 7 of the dark excavation section to form a continuous integral structure. The pouring speed is strictly controlled and poured in layers to ensure that the concrete densely fills the space in the formwork. The pouring height and fluidity are monitored through the observation port, and problems in the pouring process are adjusted in time to ensure that the concrete is evenly filled. After pouring, the concrete surface is properly vibrated and leveled to ensure the quality of the concrete, and the curing material is promptly covered for moisturizing and curing; After the concrete reaches the designed strength, remove the formwork in a reasonable order: first remove the top plate 6 formwork, then remove the side wall 5 formwork, and finally remove the bracket. Clean up the construction site, sort out and recycle the formwork and bracket, and prepare for subsequent construction. Re-erect the duct plate 8 bracket, manually chisel away the bottom concrete of the duct lower wall 7 to expose the straight section of the pre-buried "L"-shaped steel bar, and manually straighten it to prepare for subsequent welding; Afterwards, the joints between the duct slab 8 templates need to be handled carefully, especially the connection between the duct lower connecting wall 7 and the duct slab 8, to ensure that there will be no leakage during concrete pouring. The duct slab 8 steel bars are welded to the adjusted duct lower connecting wall 7 to enhance the connection strength between the two and ensure the integrity of the structure. During the binding process, a support frame is used to ensure that the steel bars are correctly positioned before pouring to avoid displacement. After the steel bars are tied, a ground pump is used to pour concrete. The pouring speed needs to be controlled during pouring to avoid deformation of the template or uneven concrete due to excessive speed. Multiple rows of pouring holes are set in the height direction of the side wall 5, and the pouring speed of the layered pouring side wall 5 is controlled to not exceed 3 meters per hour; when the top plate 6 is poured, since the duct lower connecting wall 7 is lower than the top plate 6, the concrete will naturally flow into the duct lower connecting wall 7. The pouring speed should be controlled to not exceed 2 meters per hour to ensure that the concrete can evenly fill the space in the template, and the pouring height and fluidity are monitored through the observation port.

[0026] Working principle: By pouring the side wall 5, top plate 6 and the lower connecting wall 7 of the duct into an integral structure at one time, the gaps and loose fitting problems that may be caused by pouring in stages are avoided. This integrated pouring ensures the close connection between the components, enhances the integrity and stability of the structure, and reduces the risk of relative displacement between different parts. "L"-shaped connecting steel bars are set on the side wall 5 and connected by straight threaded sleeves, which not only enhances the connection strength and reliability, but also provides convenient conditions for the subsequent welding of the steel bars of the duct flat plate 8; the connecting steel bar joints are staggered by 50% in the same section to disperse stress and enhance the connection strength, ensuring the safety and durability of the structure. The total station is used to accurately mark the position of the lower connecting wall 7 of the duct on the top plate 6 steel bars that have been tied as the line-laying position, ensuring the accurate position of the lower connecting wall 7 of the duct; for the installation of the template of the lower connecting wall 7 of the duct, special attention is paid to its verticality and geometric accuracy to ensure that the templates are tightly combined during concrete pouring to prevent leakage and ensure the quality of concrete pouring. The bottom of the connecting steel bar is anchored into the upper surface of the duct plate 8, and the top is spot welded to the top plate 6 steel bar, and a welding connection end is reserved to facilitate the subsequent welding of the duct plate 8 steel bar. This design ensures the effective connection between the duct plate 8 and the lower connecting wall 7 of the duct, and enhances the integrity and airtightness of the entire structure. When installing the top plate 6 template, space is reserved for the template of the lower connecting wall 7 of the duct, and the template of the lower connecting wall 7 of the duct is installed after the installation and reinforcement of the top plate 6 template is completed, thereby ensuring the integrity of the lower connecting wall 7 of the duct and the top plate 6 during concrete pouring.

[0027] Through the above measures, this construction method not only solves the problem that the concrete pouring cannot be completely close to the flat-top frame structure of the newly built station when it is located under the top plate of the completed station structure, but also improves the construction quality, safety and functionality through a series of innovative designs and technical measures. It is particularly suitable for complex engineering environments such as underground stations.

[0028] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A track top air duct structure of a flat roof structure of a dark excavation station, characterized by: The invention comprises a concealed excavation section bottom plate (4), side walls (5), a top plate (6), an air duct lower connecting wall (7) and an air duct flat plate (8), wherein the concealed excavation section bottom plate (4) is connected to the side walls (5), the side walls (5) are vertically arranged directly below the top plate (6), the air duct lower connecting wall (7) is arranged below the top plate (6), the side walls (5), the air duct lower connecting wall (7) and the top plate (6) are connected by steel bars and cast into an integrated structure, and the air duct flat plate (8) and the air duct lower connecting wall (7) are welded together.

2. The track top air duct structure and construction method of the flat-top structure of the underground excavation station according to claim 1 are characterized by: The side wall (5) is provided with connecting steel bars, the connecting steel bars are connected by straight threaded sleeves, and the connecting steel bars are "L" shaped.

3. The track top air duct structure and construction method of the flat-top structure of the underground excavation station according to claim 2 are characterized by: Reinforcement steel bars are arranged inside the top plate (6), and the reinforcement steel bars are welded together with the connection steel bars.

4. The track top air duct structure of the flat roof structure of the underground excavation station according to claim 3 is characterized by: The bottom of the connecting steel bar is anchored into the upper surface of the air duct flat plate (8), and the top of the connecting steel bar is spot welded and fixed to the steel bar of the top plate (6).

5. A construction method for a track-top air duct structure of a flat-top structure of a dark-excavated station, characterized in that: The track top air duct structure of the flat-top structure of the underground excavation station according to any one of claims 1 to 4 comprises the following steps: Step 1: construct the bottom plate (4) of the dark excavation section and set up the frame to tie the side wall (5) and top plate (6) with steel bars; Step 2: Tie the steel bars of the lower wall of the air duct (7) and install the formwork; Step 3: Concrete pouring of the side walls (5), top plate (6) and lower connecting wall of the dark excavation section; Step 4: Remove the formwork and straighten the steel bars of the duct slab (8); Step 5: Duct slab (8) reinforcement binding, formwork installation, and concrete pouring; Step 6: Remove the template of the duct plate (8).

6. The construction method of the track top air duct structure of the flat roof structure of the underground excavation station according to claim 5 is characterized by: In step 1 and step 2, a dark excavation section reinforcement body (2) is provided on the dark excavation section, and a dark excavation section preliminary support structure (3) is provided inside the dark excavation section reinforcement body (2). Then, the steel bars of the bottom plate (4) of the dark excavation section structure are tied, and the side wall (5) connecting steel bars are reserved. After the steel bars are tied, concrete is poured. Then, a support system of the side wall (5) and the top plate (6) is set up. The support system is used as an operating platform for steel bar tying before the template is installed. During the tying process, the side wall (5) connecting steel bars are reserved. The connecting steel bar joints are staggered by 50% in the same section to disperse stress and enhance the connection strength.

7. The construction method of the track top air duct structure of the flat roof structure of the underground excavation station according to claim 5 is characterized by: In step 3 and step 4, the position of the lower connecting wall (7) of the air duct is accurately marked on the top plate (6) steel bars that have been tied as the laying-out position using a total station. The upper end of the connecting steel bar should be anchored into the steel bar skeleton of the top plate (6) and spot welded to the steel bars of the top plate (6) to ensure a firm connection. The connecting steel bar should be located at the elevation of the upper surface of the air duct plate (8) to ensure that the steel bars of the air duct plate (8) can be effectively welded to it. In order to facilitate the installation and removal of the template, the bottom of the connecting steel bar needs to be placed inside the template, leaving a space for welding. After all the reserved reinforcement binding work is completed, the template is installed. First, the side wall (5) template is installed, and then the top plate (6) template. For the position of the lower wall (7) of the duct, space should be reserved when the template is installed. After the top plate (6) template is installed and reinforced, the lower wall (7) template of the duct is installed to ensure the integrity of the lower wall (7) of the duct and the top plate (6) during concrete pouring. Use a plumb bob to check the verticality of the lower wall (7) template of the duct to ensure its accurate position, thereby ensuring the geometric accuracy of the duct structure.

8. The construction method of the track top air duct structure of the flat roof structure of the underground excavation station according to claim 7 is characterized by: In step 5 and step 6, after the support system is stabilized, the duct slab (8) template is installed. The joints between the duct templates need to be handled tightly to prevent leakage during concrete pouring. For the duct template at the connection between the duct lower wall (7) and the duct slab (8), special attention should be paid to ensure that they are tightly combined to ensure the quality of concrete pouring. After the duct template is installed, the duct slab (8) steel bars are tied. The duct slab (8) steel bars are welded to the adjusted duct lower wall (7) connecting steel bars. During the tying process, a support frame is used to ensure that the steel bars are correctly positioned before pouring to avoid displacement. After the steel bars are tied, a ground pump is used to pour concrete. The pouring speed needs to be controlled during pouring to avoid deformation of the template or uneven concrete due to excessive speed. When pouring with a ground pump, the side wall (5) is set in the height direction. Multiple rows of pouring holes are used, and the pouring speed of the side wall (5) is controlled to be no more than 3 meters per hour. After pouring to the height of the bottom row of pouring holes, the pouring holes are gradually moved to the upper layer, and the lower layer of pouring holes are closed. When pouring the top plate (6), since the lower connecting wall (7) of the air duct is lower than the top plate (6), the concrete will naturally flow into the lower connecting wall (7) of the air duct. The pouring speed should be controlled to be no more than 2 meters per hour to ensure that the concrete can evenly fill the space in the template, and the pouring height and fluidity are monitored through the observation port. After the pouring is completed, the concrete surface is properly vibrated and leveled to ensure the quality of the concrete, and the curing material is promptly covered for moisturizing curing; first remove the top plate (6) template, then remove the side wall (5) template, and finally remove the bracket. After the template is removed, clean up the construction site, sort out and recycle the template and bracket, and prepare for subsequent construction.

Images