A dry dock system for a pipeline prefabricated immersed tube tunnel and a prefabrication method thereof

Abstract

The present application relates to the technical field of immersed tunnel construction, in particular to a dry dock system for flow line prefabricated immersed tunnel and a prefabrication method thereof, which prefabricates the immersed tunnel by adopting a regional synchronous construction mode, and finally the prefabricated immersed tunnel is once equipped and then is docked out by floating, so that the prefabrication period is short, the required site scale is small, the semi-submersible barge and the wharf are not limited, the prefabrication site scale can be adjusted according to the actual construction condition, the land occupation is flexible, a single dock or a double dock can be arranged, the environmental adaptability is good, and the dry dock is particularly suitable, the axis site is not required to be widened, and the addressing difficulty of the temporary construction site is reduced.

Description

Technical Field

[0001] This invention relates to the field of immersed tunnel construction technology, and in particular to a dry dock system for automated prefabrication of immersed tunnels and its prefabrication method. Background Technology

[0002] Existing methods for immersed tunnel prefabrication mainly employ dry docking and factory methods. The dry docking method involves a prefabrication site primarily consisting of a dock area and a dock gate. Prefabrication of the immersed tunnel section is carried out directly on the ground at the bottom of the dock. After prefabrication, water is pumped into the dock area to align it with the external sea level, causing the immersed tunnel to float. Then, the dock gate is opened to allow it to leave the dock. Because the dry docking method involves prefabrication and floating / shipping within the same dock area, prefabrication and shipment cannot be carried out simultaneously, preventing a continuous flow of operations. This results in significant time pressure; prefabrication of a batch of tunnel sections typically takes 8 to 11 months, and is greatly affected by factors such as site conditions and weather, leading to a long construction period. Furthermore, the existing dry docking method involves prefabrication directly on the ground at the bottom of the dock without a bottom formwork. The bottom of the immersed tunnel is a concealed structure, making it difficult to guarantee its quality during casting. Additionally, waterproof steel plates are installed at the bottom to prevent leakage, and complex polyurea packaging processes are applied to the exterior, which is economical and expensive.

[0003] The advantages of the existing factory method are fast prefabrication speed, good quality, good risk management, and the factory can be reused. However, it requires a large site, and it is necessary to build large factories, shallow docks and deep docks, or to build shipping wharves and bottom harbor basins and configure semi-submersible barges to meet the requirements of immersed tube prefabrication, launching and shipping. Specifically, one method for prefabricating reinforced concrete immersed tubes, as provided in the patent document with application number CN201310633846.4, involves an assembly line operation where steel reinforcement processing, binding, and pouring are carried out in a prefabrication workshop. A dock (a combination of shallow and deep docks) is set up near the prefabrication workshop. After the immersed tube is prefabricated, the shallow dock gate is opened and the tube is transported to the shallow dock area for the first outfitting. After the outfitting is completed, the shallow dock gate is closed, and water is poured into the dock until the immersed tube floats, thereby directly pulling the immersed tube from the shallow dock area to the deep dock area. Then, water is released to make the shallow dock area meet the conditions for dry construction operations in preparation for the outfitting of the next tube section. While the immersed tube in the deep dock area is being outfitted a second time, the immersed tube in the shallow dock area is being outfitted a first time. After the second outfitting is completed, the deep dock gate is opened, and the immersed tube is pulled out of the dock under the action of water buoyancy. Another method for prefabricating reinforced concrete immersed tunnel sections involves completing the outfitting process in a prefabrication workshop, then transferring the tunnel sections to a loading dock using trolley mechanisms or cranes, and finally transporting them by semi-submersible barges. While the factory method offers the advantage of a shorter construction period due to assembly line operations, it is limited by site and economic constraints. It requires finding sites far from the tunnel site, often resulting in difficulties finding temporary construction sites or long transportation distances, and incurring high costs for both temporary construction and transportation. This method is not feasible when site size is limited to accommodate both shallow and deep docks, or when semi-submersible barge transportation is not feasible. Therefore, for these situations, especially in areas with limited space and significant constraints such as inland waterways and urban river crossings, it is necessary to propose a new construction method to adapt to the on-site construction conditions. Summary of the Invention

[0004] The purpose of this invention is to address the problems of existing technologies that require either the construction of shallow and deep docks for floating and transporting immersed tunnel sections using the factory prefabrication method, which requires a large site area, or the construction of a transport wharf and a bottom-sitting harbor basin for transporting immersed tunnel sections via semi-submersible barges, which places high demands on the construction conditions of temporary sites and is not suitable for construction in areas with limited space. The invention provides a dry dock system and prefabrication method for assembly line prefabrication of immersed tunnel sections, which can accommodate the contradiction between site size limitations and construction period.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A prefabrication method for immersed tunnels based on a dry dock system assembly line, wherein the dry dock system includes a connected rebar tying dock and an outfitting dock, wherein the rebar tying dock has a rebar tying area and a casting area, an inner dock door is provided between the rebar tying dock and the outfitting dock for connection and disconnection, and an outer dock door is provided on the water-facing side of the outfitting dock for connection and disconnection. The construction includes the following steps: Step 1: Precast the reinforcing steel cage for the sinking tube in the reinforcing steel binding area; Step two: Move the steel reinforcement cage to the pouring area for pouring operations; Step 3: After the casting is completed, the immersed tube is moved to the outfitting dock for outfitting. Step 4: Close the inner dock door and fill the outfitting dock with water to make the submerged tube float. Step 5: Open the outer dock door and move the immersed tube out of the dock.

[0006] This invention separates the rebar tying, pouring, and outfitting processes of the immersed tunnel prefabrication process into different areas and performs them simultaneously. This allows for a streamlined operation to quickly complete the prefabrication of the immersed tunnel, resulting in a short prefabrication cycle. After the pouring process is completed, the tunnel undergoes outfitting once. It can then be unloaded after being filled with water in the outfitting dock. Compared to the traditional factory method of prefabricating immersed tunnels, which requires a transition from a shallow dock to a deep dock for unloading, this invention shortens the production line while maintaining the same prefabrication efficiency. It also reduces the amount of construction work required for the outfitting dock, minimizes the prefabrication site space, and lowers construction difficulty and investment costs. The first outfitting of the immersed tunnel mainly involves the installation of a series of temporary auxiliary facilities before the tunnel floats, including ballast water tanks, ballast water piping systems, ballast water pumps, temporary ventilation, lighting, and end sealing doors, to ensure the tunnel's airtightness during floating and installation.

[0007] This invention improves upon the traditional factory method, reducing the site size while maintaining the same prefabrication efficiency. It is not limited by the availability of ships and docks, has low requirements for construction conditions of temporary sites, and can meet the construction conditions of dry dock sites near tunnel sites, thereby reducing transportation costs. It is suitable for construction in areas with limited space.

[0008] Preferably, a jacking device is used to push the reinforcing cage from the rebar binding area to the pouring area along the transfer track. A base frame is provided below the reinforcing cage, and a load-bearing trolley is fixedly installed below the base frame. The load-bearing trolley can roll along the transfer track, which helps reduce friction. At the pouring area, a gantry crane lifts the reinforcing cage, pulls out the base frame, and returns it to the rebar binding area, allowing the reinforcing cage to be supported on the bottom formwork of the pouring platform for pouring. This invention uses a jacking method to move the reinforcing cage along the transfer track to the pouring area under the transport of the load-bearing trolley. The jacking resistance is low, the transportation cost is low, the efficiency is high, and the number and cost of trolleys used are saved.

[0009] Preferably, the immersed tube is transferred from the pouring area to the outfitting dock using a transfer trolley with lifting function. Inside the outfitting dock, the immersed tube is transferred to the outfitting platform for support. Then, the transfer trolley is withdrawn to the pouring area. The transfer trolley is reused.

[0010] Preferably, after completing an outfitting operation, the gantry crane and outfitting equipment in the outfitting dock are moved out of the outfitting dock and returned to the steel reinforcement binding dock before the inner dock door is closed, ensuring that the construction gantry crane and outfitting equipment are in a waterless area.

[0011] Furthermore, the above construction steps also include step six: after the immersed tunnel section leaves the dock, close the outer dock door and drain the outfitting dock to facilitate cleaning operations inside the outfitting dock; then open the inner dock door and move the next poured immersed tunnel section to the outfitting dock, and so on, to outfit the next section.

[0012] Preferably, the dry dock system adopts axial dry dock construction, with the position of the outer dock gate corresponding to the spatial position of the final joint of the immersed tunnel. Axial dry dock construction means that the dry dock site for prefabricated pipe sections is constructed based on the tunnel site and shares the excavation section with the immersed tunnel. This can further reduce the occupation of the construction site and the transportation distance of the immersed tunnel, reduce the project cost, and facilitate the construction of the final joint of the immersed tunnel.

[0013] Preferably, the outfitting dock is used as the outfitting area, and the rebar tying area, pouring area and outfitting area are set up in sequence, which helps to improve the efficiency of immersed tube prefabrication and simplify the factory layout.

[0014] This invention also provides a dry dock system for implementing the above-mentioned prefabrication method, comprising a rebar tying dock, an outfitting dock, and a secondary outfitting area. The rebar tying dock contains a rebar tying area and a casting area. The rebar tying dock and the outfitting dock are connected, and an inner dock door is provided between them for connection and disconnection. An outer dock door is provided on the water-facing side of the outfitting dock for connection and disconnection. The outfitting dock is located in the land-based buried section of the tunnel construction, and the secondary outfitting area is located in the open section of the underwater foundation trench adjacent to the land-based buried section. Using this dry dock system for prefabricating immersed tunnel sections requires less site space, has a shorter prefabrication cycle, and allows for quality control. It also reduces dredging costs for transport channels, storage areas, and turning areas, and lowers the construction costs of temporary sites.

[0015] This invention also provides a prefabrication method for immersed tunnels based on a dry dock system assembly line. The dry dock system includes an outfitting dock, within which a casting platform is installed. An outer dock gate is provided between the outfitting dock and the water area for connection and disconnection. The construction process includes the following steps: Step 1: Transfer the precast steel cage to the pouring platform for pouring operations; Step 2: After the immersed tube is poured, the immersed tube on the pouring platform will be outfitted again. Step 3: After the outfitting work is completed, water is poured into the outfitting dock to make the submerged tube float. Step 4: Open the outer dock door, move the immersed tube out of the dock, and carry out secondary outfitting.

[0016] This invention divides the steel reinforcement binding, pouring, and outfitting processes of the immersed tunnel prefabrication process into two simultaneous workstations. The pouring and outfitting processes are carried out at the same workstation, where pouring is completed first, followed by outfitting. After one outfitting cycle, water is pumped into the outfitting dock, causing the immersed tunnel to float and be unloaded. This method is not limited by finding vessels or docks, resulting in a shorter prefabrication cycle and a smaller prefabrication site. It is suitable for construction in areas with limited space, helping to reduce construction difficulty and investment costs. The prefabrication of the steel reinforcement cage can be carried out either inside or outside the dry dock, depending on the specific site conditions.

[0017] Therefore, as a preferred option, the rebar binding area of ​​the precast rebar cage is located outside the dock, and the rebar cage is moved to the casting platform by a gantry crane. This scheme adopts a single-dock mode for the dry dock system, which reduces the amount of excavation and cofferdam work, and occupies less land, thus reducing the amount of backfilling work in the later stage.

[0018] Alternatively, as another preferred option, the dry dock system also includes a rebar tying dock, i.e., the dry dock system adopts a dual-dock system, with the rebar tying dock used as the rebar tying area. The rebar tying dock is connected to the outfitting dock, and an inner dock door is provided between the rebar tying dock and the outfitting dock for connection and disconnection. When transferring the rebar cage, a jacking device is used to push the rebar cage along the transfer track to the casting platform of the outfitting dock. A bottom frame is provided under the rebar cage, and a load-bearing trolley is installed under the bottom frame. The load-bearing trolley can roll along the transfer track. The immersed tunnel is first poured on the casting platform, and then outfitting is carried out. After one outfitting is completed, the outfitting gantry crane and outfitting equipment are returned to the rebar binding dock, the inner dock door is closed, and then water is poured into the outfitting dock to make the immersed tunnel float. The outer dock door is opened, and the immersed tunnel is hoisted out of the dock. After leaving the dock, the outer dock door is closed, the outfitting dock is drained and cleaned, the inner dock door is opened, and the next rebar cage is pushed from the rebar binding area to the casting platform of the outfitting dock. This cycle of immersed tunnel pouring and outfitting is repeated.

[0019] Accordingly, based on the above-described prefabrication method, this invention also provides a dry dock system for implementing the prefabrication method. The dry dock system includes a land-based buried section for tunnel construction and an open underwater trench section adjacent to the land-based buried section. A dry dock is set up on the land-based buried section, and a secondary outfitting area is set up on the open underwater trench section. The dry dock is used for pouring and primary outfitting operations, and the pouring and primary outfitting operations are located at the same work station. Using this dry dock system for prefabricating immersed tunnels requires a smaller site area, has a shorter prefabrication cycle, and allows for quality control. It also reduces the cost of dredging and transporting the immersed tunnels, lowers the construction costs of temporary sites, and reduces the amount of backfilling work required later.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The dry dock system and its prefabrication method provided by this invention have a short prefabrication cycle, require a small site size, and have low cost. They are not limited by semi-submersible barges and wharves, reducing the difficulty of finding temporary construction sites and making them suitable for construction in areas with limited space.

[0021] 2. The dry dock system and its prefabrication method provided by the present invention can conditionally combine the pipe section prefabrication site with the tunnel shore section based on the tunnel site construction. That is, the dry dock and the tunnel shore section share a part of the foundation pit excavation and support, which helps to reduce the occupation of the construction site and some engineering costs. After the prefabricated pipes are pulled out from the dock, they can be directly floated and installed along the longitudinal direction of the tunnel foundation trench in the water, thereby reducing the cost of waterway dredging.

[0022] 3. This invention adopts an improved factory method for prefabricating immersed tubes in a dry dock. Compared with the dry dock method, it solves the problem that the bottom of the immersed tube is a hidden project when it is prefabricated in a dry dock, eliminates the need for waterproof steel plates at the bottom of the immersed tube, and also solves the problem of long cycle time compared with the traditional dry dock method for prefabricating immersed tubes. Attached Figure Description

[0023] Figure 1 This is a top view of the prefabricated immersed tubes in the dry dock system assembly line of Example 1; Figure 2 This is a plan view of the dry dock system bottom layout in Example 1; Figure 3 yes Figure 1 Longitudinal section view at point A1-A1 (gantry crane equipment omitted); Figure 4 yes Figure 3 Enlarged view of point C1; Figure 5 yes Figure 3 Enlarged view of point C2 in the middle; Figure 6 yes Figure 1 Longitudinal sectional view of A2-A2; Figure 7 yes Figure 1 Cross-sectional view of section B1-B1; Figure 8 yes Figure 7 A schematic diagram of the structure of the trolley carrying the steel reinforcement cage at point C3; Figure 9 yes Figure 1 Cross section view of B2-B2; Figure 10 yes Figure 9 Enlarged view of point C4 in the middle; Figure 11 yes Figure 1 Cross-sectional view of B3-B3 (cross-sectional view of the inner dock area); Figure 12 yes Figure 1Cross section view of B4-B4 (cross section view of the outfitting area); Figure 13 yes Figure 12 Enlarged view of point C5 in the middle; Figure 14 yes Figure 1 Cross-sectional view of B5-B5 (cross-sectional view of the outer dock area); Figure 15 This is a top view of the prefabricated immersed tubes in the dry dock system assembly line in Example 2; Figure 16 yes Figure 15 Longitudinal sectional view of A3-A3; Figure 17 yes Figure 15 Cross-sectional view of section B6-B6; Figure 18 This is a top view of the prefabricated immersed tubes in the dry dock system assembly line in Example 3; Figure 19 yes Figure 18 Longitudinal sectional view of A4-A4; Figure 20 yes Figure 18 Cross section view of section B7-B7.

[0024] Icon: 10 - Steel Rebar Processing Plant 20-Reinforced concrete binding dock; 21-Dock top ground; 22-Dock lowering passage; 23-Dock bottom water ditch; 24-Dry dock waterproofing curtain. 30-Rebar binding area; 31-Plant gantry crane 1; 311-Crane 1; 32-Plant rail 1; 33-Rebar cage; 34-Shifting rail; 35-Base frame; 351-Load-bearing trolley; 36-Pushing device. 40 - Pouring area; 41 - Factory gantry crane 2; 411 - Crane 2; 42 - Factory track 2; 43 - Track beam 1; 431 - Trolley track; 44 - Track beam 2; 45 - Bottom formwork; 46 - Inner formwork; 47 - Outer formwork; 48 - Concrete pouring machine; 481 - Pump pipe. 50 - Inner dock entrance area, 51 - Inner dock pier, 52 - Inner dock gate, 53 - Inner dock entrance bottom plate. 60-Outfitting dock, 61-Factory gantry crane 3, 62-Factory rail 3, 63-Passive support, 64-Shifting trolley, 70 - Outer dock area, 71 - Outer dock pier, 72 - Outer dock gate, 73 - Outer dock bottom plate 80 - Secondary outfitting area, 81 - Immersed tunnel section, 90-buttress. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1 This embodiment provides a dry dock system and prefabrication method for prefabricated immersed tunnel sections. The dry dock system in this embodiment fully utilizes the economic advantages of axial dry docks. It uses the foundation trenches of the land-based buried and open sections of the tunnel as the dry dock, and the underwater immersed tunnel foundation trench as a transport channel and secondary outfitting area. This avoids the problems of long-distance floating transport of the immersed tunnel sections and the need for separate secondary outfitting or turning areas. Simultaneously, it fully utilizes the working space of the final joint as the operating space for the dock gate, avoiding the problems of secondary dam construction and long water-stopping time required after the final immersed tunnel section is installed, which are inherent to axial dry dock methods.

[0028] In this embodiment, the dry dock system specifically adopts a dual-dock system connected in series, such as... Figures 1-14 As shown, the facility includes a steel reinforcement processing plant 10, a steel reinforcement binding dock 20, an inner dock entrance area 50, an outfitting dock 60, an outer dock entrance area 70, and a secondary outfitting area 80. The steel reinforcement processing plant 10 is located on the ground 21 at the top of the dock. A dry dock water-stop curtain 24 is also installed vertically from the top of the dock to the ground to enclose the dry dock site on the land side and prevent surrounding groundwater from flowing into the dock. Dock bottom ditches 23 are provided along the bottom edges of the steel reinforcement binding dock 20 and the outfitting dock 60 for dry dock drainage. The steel reinforcement binding dock 20 is used for steel reinforcement binding, equipment system conversion, and concrete pouring, while the outfitting dock 60 is used for the primary outfitting of pipe sections and the floating of pipe sections out of the dock. Correspondingly, the steel reinforcement binding dock 20 is located on the land side and is the inner dock, while the outfitting dock 60 is near the water and is the outer dock. The rebar tying dock 20 is equipped with a rebar tying area 30 and a pouring area 40. A tying platform is arranged corresponding to the rebar tying area 30, and a gantry crane 31 and a hoist 311 are arranged above the tying platform for hoisting operations. A pouring platform is arranged corresponding to the pouring area 40, and a gantry crane 41 and a hoist 411 are arranged above the pouring platform, along with a concrete pouring machine 48 and a pump pipe 481, etc., for pouring operations. An outfitting dock 60 is equipped with an outfitting platform, and a gantry crane 61 and related outfitting equipment are arranged above the outfitting platform for outfitting operations. The tying platform, pouring platform, and outfitting platform each provide adaptive support for the current prefabrication process of the immersed tube 81 within their respective functional areas. Figure 3 , Figure 5As shown, the working surfaces of the binding platform, casting platform, and outfitting platform are all set at the same elevation, while the elevation of the ground where the casting platform and outfitting platform are located is lower than the elevation of the ground where the binding platform is located. This is to facilitate construction work under the casting platform and outfitting platform, and to set up the construction of the binding platform section in the space above the working surface of the platform. After the prefabrication of the reinforcing cage 33 of the pipe in the binding area is completed, it can be smoothly moved to the casting platform on the same plane of each platform and the conversion of the support system is completed. The inner dock area 50 is equipped with inner dock piers 51 and inner dock gates 52. The inner dock area 50 is located between the steel reinforcement binding dock 20 and the outfitting dock 60 to isolate the two dock areas and serve as a connection and disconnection function to prevent water from entering the steel reinforcement binding dock 20 when water is poured into the outfitting area. The bottom plate 53 of the inner dock area serves as the dock bottom foundation of the inner dock area 50, and its elevation is consistent with the elevation of the dock bottom foundation of the pouring area 40 on both sides and the outfitting area. The outer dock area 70 is located on the water-facing side of the outfitting dock 60 and is equipped with the exit of the immersed tube 81. That is, the outer dock piers 71, the outer dock gate 72, and pumping stations are arranged. The water area corresponding to the immersed tube tunnel foundation trench outside the outer dock gate 72 serves as the transportation channel for the immersed tube 81 and the secondary outfitting area 80. Specifically, the outer dock gate 72 is positioned at the final joint location in the underwater trench. The top elevation of the outer dock bottom plate 73 (i.e., the dock bottom foundation of the outer dock area 70) is flush with the elevation of the bottom foundation surface of the final joint. This ensures that both the dock gate and the final joint can be operated within the final joint space without affecting the installation of the final pipe section. After the final pipe section is installed, the outer dock gate 72 can be closed promptly to allow the outfitting dock 60 to drain water in time, ensuring the rapid construction of the onshore tunnel section at the dry dock location. Once the onshore docking tunnel within the dock is completed, water can be pumped between the docking end and the outer dock gate, and the outer dock gate can be opened and removed. This does not affect the subsequent buried section construction at the onshore docking end, nor does it affect the simultaneous water sealing of the final joint at the outer dock gate location in the water, or the construction progress of the final joint within the tunnel. This allows for parallel operations on both the onshore and underwater construction surfaces, thereby accelerating the construction progress and shortening the construction period.

[0029] Specifically, such as Figure 2 , Figure 4 , Figure 8In the rebar binding area 30, several parallel shifting tracks 34 are provided corresponding to the binding platform positions. Several load-bearing trolleys 351 are mounted on the shifting tracks 34. The load-bearing trolleys 351 can roll along the shifting tracks 34. Each load-bearing trolley 351 on the shifting track 34 is connected to a base frame 35 at the top, which connects several load-bearing trolleys 351 into a whole, facilitating longitudinal shifting. The base frame 35 includes several rows of square steel and a pushing beam. The pushing beam is horizontally fixed to the ends of the several rows of square steel, making the several rows of square steel into a whole, ensuring that each load-bearing trolley 351 can move synchronously during pushing. The base frame 35 supports the reinforcing cage 33. The shifting track 34 uses channel steel for limiting. A jacking device 36 is set at the land end of the binding platform. The jacking device 36 pushes the jacking crossbeam at the end of the base frame 35, that is, it synchronously pushes the load-bearing trolley 351. The binding platform is equipped with workshop tracks 32 on both sides for the workshop gantry crane 31 to move, thereby adapting to the adjustment of the reinforcing bar binding position. The workshop tracks 32 are set through the reinforcing bar binding dock 20, that is, the workshop tracks 32 run from both sides of the reinforcing bar binding platform to both sides of the pouring platform, which facilitates the movement of the workshop gantry crane 31 above the pouring platform. After the binding platform completes the binding of the submerged reinforcing cage 33, the jacking device 36 is driven to push the base frame 35 to carry the submerged reinforcing cage 33 to move. The reinforcing cage 33 moves along the shifting track 34 with the load-bearing trolley 351 under the base frame to the pouring area 40 and is positioned. This method of moving the steel cage 33 has low friction and is more stable and simpler to operate than the method of using a gantry crane to lift and move the steel cage 33. It can also avoid adverse situations such as bending and deformation of the steel bars.

[0030] In the pouring area 40, such as Figure 2 , Figure 9 , Figure 10As shown, the casting platform is equipped with two factory rails 42 on both sides along the line direction for the movement of the factory gantry crane 41. Corresponding to the work position of the casting platform, there are four track beams 43 and four track beams 44 on the ground. The bottom of track beams 43 and 44 are all spaced with foundation piles. The position of track beam 43 corresponds to the lower part of the wall of the immersed tube 81, and the position of track beam 44 corresponds to the position of the tunnel passage of the immersed tube, so as to facilitate uniform force distribution and force transmission. Among them, track beam 43 in the casting area 40 extends through the inner dock gate 52 to the outfitting area and is also set as the foundation of the outfitting platform. Each track beam 43 is equipped with a trolley track 431 and two rows of supports 90 along the transport direction. The two rows of supports 90 are located on both sides of the trolley track 431 and are spaced apart at the work positions of the casting platform and outfitting platform, forming the main body of the respective platform. A row of supports 90 is also spaced apart on the track beam 44 at the casting work position to support the casting load of the immersed tube bottom plate. A transfer trolley 64 is arranged on the trolley track 431. The transfer trolley 64 includes multiple trolley bodies, a drive device on the trolley body for driving the trolley body to move, and jacks set on the trolley body. The multiple trolley bodies are spaced apart, and adjacent trolley bodies are connected by a connecting rod. The transfer trolley 64 is used to move the cast immersed tube 81 along the trolley track 431 to the outfitting platform in the outfitting area, that is, the supports 90 at the outfitting work position.

[0031] The support 90 at the pouring station is equipped with a bottom formwork 45 on top, and the moving trolley 64 is equipped with a movable bottom formwork 45 on top. Before the pouring operation, the bottom formwork 45 is leveled to support the pouring operation. When the steel cage 33 is pushed onto the pouring platform, the load trolley 351 is supported on the bottom formwork 45. Then, the steel cage 33 is lifted by the first gantry crane 31 and the second gantry crane 42. Then, the bottom frame 35 at the bottom of the steel cage 33 is removed and returned to the binding area, saving time and effort. After the pouring operation of the immersed tube 81 in the pouring area 40 is completed, the immersed tube 81 is lifted by the movable moving trolley 64 and moved to the outfitting area along the through trolley track 431.

[0032] Each support 90 in the outfitting area is equipped with a passive support 63. This passive device is used for height adjustment, ensuring that the immersed tube 81 can be placed horizontally on the passive support 63. The passive support 63 is an existing device and will not be described further. On both sides of the outfitting platform in the outfitting area are three factory rail tracks 62. These tracks allow the factory gantry crane 61 in this area to move, facilitating outfitting in one go. The three factory rail tracks 62 can be set along the same route as the first factory rail track 32, simplifying the route setup and making the layout more rational.

[0033] During operation, the process flow for prefabricating immersed tube 81 on the assembly line is as follows: (1) The steel bars are processed in the steel bar processing plant 10 outside the dock; (2) The processed steel bars are transported by transport vehicle along the lower dock passage 22 to the binding workshop of the binding dock. The steel bars are then used by cranes and manual labor in the workshop to bind the bottom plate steel bars and wall steel bars as a whole on the binding platform. (3) Then push the overall inner formwork 46 into the steel cage 33, and tie the top slab steel bars on the entire inner formwork 46; (4) After the steel cage 33 is tied, the bottom frame 35 of the steel cage is pushed by the jacking device 36. The bottom frame 35 carries the tied whole steel cage 33 and inner formwork 46 from the tying station to the pouring station. (5) The steel cage 33 is lifted by the crane above the binding workshop and the pouring workshop, thereby removing the bottom frame 35 under the steel cage 33 and returning it to the binding area; (6) Place the steel cage 33 on the pouring platform and install the outer formwork 47 and end formwork, and pour concrete section by section in sequence; (7) After the concrete is poured, remove the inner formwork 46 when the concrete strength is sufficient. Move the inner formwork 46 plate from the pouring platform to the steel cage 33 of the next pipe section of the binding platform and continue to bind the top plate steel of the next pipe section. That is, the removed inner formwork 46 is repeatedly applied to step (3). (8) The completed pipe section is lifted by the shifting trolley 64 under the casting platform and the jacks on the shifting trolley 64, and moved to the outfitting platform position of the outfitting dock 60. The pipe 81 is transferred to the outfitting platform. After that, the shifting trolley 64 is returned to the casting area for reuse. (9) The pipe sections are outfitted in one go using the gantry cranes and outfitting equipment in the outfitting area; (10) After outfitting is completed in one go, the gantry crane and outfitting equipment are returned to the steel reinforcement binding dock 20 (i.e., the inner dock); (11) Close the inner dock door 52 by means of a mobile crane or door opening device, and install the waterstop device for the inner dock door 52; (12) Water is injected into the outfitting dock 60 through the drainage equipment at the outer dock entrance to make the pipe section float; (13) Open the outer dock door 72, and use the cable hoisting system to hoist the pipe section out of the dock to the secondary outfitting area outside the dock, and then carry out the subsequent secondary outfitting and sinking installation procedures for the pipe section. (14) Close the outer dock gate 72, then drain the water into the outfitting dock 60 through the drainage equipment at the outer dock entrance, and then clean the outfitting dock 60. (15) Remove the waterstop device of the inner dock door 52, open the inner dock door 52 by crane or door opening mechanism, and move the next pipe section that has been poured to the outfitting dock 60 by the transfer trolley 64 on the casting platform in the steel reinforcement binding dock 20. Repeat this process to outfit the next pipe section. In this way, pipe sections are prefabricated in a production line. The prefabrication cycle of one pipe section is about 1 month.

[0034] This embodiment fully utilizes the economic advantages of the axial dry dock, using the foundation trenches of the buried and open sections of the tunnel as a dry dock factory. Combining the technological characteristics of the immersed tube 81 factory method, it proposes a dry dock factory and supporting operation process for the assembly line prefabrication of immersed tube 81. It eliminates the need to find additional sites to excavate dry docks or build factories, harbor basins, or large semi-submersible vessels, thus solving the problem of the need to construct large temporary facilities for the factory method of prefabricating immersed tube 81. Moreover, it retains the advantages of the factory method of assembly line prefabrication of immersed tube 81, such as short construction period, high quality, and controllable risks. The prefabrication cycle is 1 to 2 months.

[0035] Finally, it should be noted that the docks mentioned in this article, such as "rebar binding dock 20" and "outfitting dock 60", refer to places with high terrain on all sides and concave in the middle (general term), used for different purposes.

[0036] Example 2 This embodiment also provides a dry dock system and prefabrication method for prefabricated immersed tunnels in an assembly line. The main difference between this embodiment and Embodiment 1 is that the dry dock system in this embodiment adopts a single-dock mode, such as... Figures 15-17 As shown, the site excavation for the rebar tying dock 20 in Embodiment 1 is eliminated. The rebar tying area 30 for prefabricating the rebar cage 33 is set outside the dock, and the pouring platform is set inside the outfitting dock 60, so that the pouring and outfitting processes share the same platform. Accordingly, a gantry crane is provided above the pouring platform, and a concrete pouring machine 48 and a pump pipe 481 are arranged. Specifically, in this embodiment, the rebar tying area 30 is set near the land end of the outfitting dock 60, and gantry crane tracks are provided on both sides of the outfitting dock 60 along the line direction. The gantry crane tracks extend to the rebar tying area 30 for the gantry crane to move. The construction includes the following steps: S1. Precast submerged pipe reinforcement cage 33 in the reinforcement binding area 30 outside the dock; S2. After the binding is completed, the steel cage 33 is moved section by section to the pouring platform by the gantry crane in the steel binding area 30 for pouring operation; S3. After the immersed tube is poured, another outfitting operation is carried out on the pouring platform; S4. After completing one outfitting cycle, water is pumped into the outfitting dock 60 through the water supply and drainage equipment at the outer dock entrance to make the submerged tube 81 float. S5. Open the outer dock door 72 and hoist the immersed tube 81 out of the dock; S6. After the immersed tube 81 leaves the dock, it will be outfitted a second time. At the same time, the outer dock gate 72 will be closed, and the drainage equipment at the outer dock gate will be used to drain water from the outfitting dock 60 and clean the outfitting dock 60. The steel cage of the next pipe section, which has been tied in the binding area 30, will be moved to the outfitting dock 60 by a gantry crane. The next pipe section will be poured and outfitted in a cyclical manner.

[0037] This embodiment adopts a single-dock mode for the dry dock system, which reduces the amount of excavation and cofferdam work and the land area required, thereby reducing the amount of backfilling work in the later stage. During the operation, this embodiment divides the prefabrication process of the immersed tube 81 into two work stations for simultaneous construction in different areas. The pouring and outfitting processes are carried out at the same work station. After completing one outfitting, the tube is floated out of the dock by filling the outfitting dock 60 with water. The prefabrication cycle is about 2 months, which is not limited by finding ships and docks, and reduces the size of the prefabrication site. It is suitable for construction in areas with limited space and short distances, which helps to reduce construction difficulty and investment costs.

[0038] Example 3 This embodiment also provides a dry dock system and prefabrication method for automated prefabrication of immersed tunnels, such as... Figures 18-20 As shown, compared to Embodiment 1, the main difference in the technical solution of this embodiment is that: in this embodiment, the rebar tying dock 20 of the dry dock system is only used for rebar tying operations, while the outfitting dock 60 is used for pouring and outfitting operations. The pouring platform is set in the outfitting dock 60, allowing the pouring and outfitting processes to share the same platform. Correspondingly, several gantry cranes are arranged inside the outfitting dock for hoisting and pouring respectively. During construction, the following steps are included: S1. Precast the submerged pipe reinforcement cage 33 in the reinforcement binding area 30; S2. First, the reinforcing cage 33 is transported by the jacking device 36 through the load trolley 351 and pushed along the transfer track 34 to the pouring platform for pouring operation; when the reinforcing cage is moved to the inner dock area, it can be extended to the pouring platform by overlapping the transfer track 34 in the inner dock area and the outfitting dock, so that the transfer of the reinforcing cage 33 can be smoothly transitioned. S3. After the immersed tube is poured, another outfitting operation is carried out on the pouring platform; S4. After one outfitting is completed, the gantry crane and outfitting equipment are returned to the rebar binding dock 20, and then the inner dock door 52 is closed; S5. Fill the outfitting dock 60 with water to make the submerged tube 81 float; S6. Open the outer dock door 72, hoist the immersed tube 81 out of the dock, and carry out secondary outfitting; S7. After leaving the dock, close the outer dock door 72 and drain and clean the outfitting dock 60; S8. Open the inner dock door 52 and move the next steel cage 33 from the steel binding area 30 to the pouring platform. Repeat this process to carry out pouring and outfitting operations on the pouring platform.

[0039] This embodiment adopts a dual-dock mode, dividing the prefabrication process of the immersed tube 81—including the prefabrication of the reinforcing cage 33, pouring, and outfitting—into two separate workstations for simultaneous construction. The pouring and outfitting processes are carried out at the same workstation. After one outfitting cycle, the tube is unloaded by filling the outfitting dock 60 with water. The prefabrication cycle is approximately two months, not limited by ship availability or dock availability, and the size of the prefabrication site is reduced. This approach is suitable for construction in areas with limited length and smaller footprint, helping to reduce construction difficulty and investment costs. The prefabrication of the reinforcing cage 33 can be carried out either inside or outside the dry dock, depending on the specific site conditions.

[0040] In this paper, depending on construction needs and site conditions, two or more binding platforms, casting platforms, or outfitting platforms can be set up in the factory system, such as a two-production-line, four-platform double-dock factory or a two-production-line, six-platform double-dock factory. The two-production-line, four-platform double-dock factory can prefabricate a batch of pipe sections in two months, with two pipe sections per batch; the two-production-line, six-platform double-dock factory can prefabricate a batch of pipe sections in one month, with two pipe sections per batch. This is not limited to the examples mentioned above. Furthermore, the technical solutions in Examples 1-3 can also be used to independently select sites and construct dry-dock factories according to site conditions and needs, and are not limited to axial dry-dock construction.

[0041] The prefabrication methods provided in Examples 1-3 above adopt a phased synchronous construction approach to prefabricate immersed tunnels. The immersed tunnel components are floated out of the dock after one outfitting. The prefabrication cycle is short, the required site size is small, it is not restricted by semi-submersible barges and wharves, and the size of the prefabrication site can be adjusted according to the actual construction conditions. It is flexible in terms of land occupation, and can set up single docks or double docks. It has good environmental adaptability and also reduces the difficulty of finding temporary construction sites.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A prefabrication method for immersed tunnels based on a dry dock system assembly line, characterized in that, The dry dock system includes a connected rebar tying dock (20) and an outfitting dock (60). The rebar tying dock (20) contains a rebar tying area (30) and a pouring area (40). The rebar tying area (30) is equipped with a shifting track (34). The shifting track (34) has a load-bearing trolley (351) that can roll along it and a base frame (35) mounted on the load-bearing trolley (351) as a tying platform supporting the rebar cage (33). The pouring area (40) contains a pouring platform. An inner dock door (52) is provided between the rebar tying dock (20) and the outfitting dock (60) for connection and disconnection. A through trolley track (431) is provided between the pouring area (40) and the outfitting dock (60), and a moving trolley (64) is provided on the trolley track (431); an outfitting platform is provided in the outfitting dock (60), the outfitting platform includes spaced-apart supports (90) and passive supports (63) provided on the supports (90); the outfitting dock (60) is located in the land buried section of the tunnel construction; an outer dock door (72) is provided on the water-facing side of the outfitting dock (60) for opening and closing; the position of the outer dock door (72) corresponds to the final joint position of the underwater foundation trench; the construction includes the following steps: Step 1: Precast the steel cage (33) of the sinking tube (81) in the steel reinforcement binding area (30); Step 2: The steel cage (33) is moved to the pouring area (40) for pouring operation. Specifically, the steps include: pushing the bottom frame (35) with the jacking device, using the bottom frame (35) to carry the steel cage (33) from the binding position to the pouring position, then lifting the steel cage (33) with the crane, moving the bottom frame (35) out and back to the steel binding area (30), and lowering the steel cage (33) onto the pouring platform. Step 3: After the casting is completed, the immersed tube (81) is moved to the outfitting dock (60) for an outfitting operation. Specifically, the steps include: lifting the cast-in-place immersed tube (81) by the transfer trolley (64) under the casting platform and the jacks on the transfer trolley (64), and then moving it to the outfitting platform position of the outfitting dock (60), transferring the immersed tube (81) onto the outfitting platform, and then returning the transfer trolley (64) to the casting area (40) for reuse. Step 4: Close the inner dock door (52) and fill the outfitting dock (60) with water to make the sinking tube (81) float. Step 5: Open the outer dock door (72), and move the immersed tube (81) directly from the outfitting dock (60) out of the dock to the secondary outfitting area outside the dock, and then carry out secondary outfitting.

2. The prefabrication method according to claim 1, characterized in that, After completing the outfitting operation, the gantry crane and outfitting equipment are moved out of the outfitting dock (60), returned to the steel reinforcement binding dock (20), and then the inner dock door (52) is closed.

3. The prefabrication method according to claim 1 or 2, characterized in that, It also includes step six: after the immersed tube (81) leaves the dock, close the outer dock door (72) and drain the outfitting dock (60); then open the inner dock door (52) and move the next cast immersed tube section to the outfitting dock (60).

4. A prefabrication method for immersed tunnels based on a dry dock system assembly line, characterized in that, The dry dock system includes an outfitting dock (60), which is located in the land-based buried section of the tunnel. A casting platform is installed inside the outfitting dock (60). An outer dock door (72) is provided on the water-facing side of the outfitting dock (60) for opening and closing. The construction includes the following steps: The precast steel cage (33) is moved to the casting platform for casting. After the pouring is completed, the sinking pipe (81) on the pouring platform will be fitted out again. After the outfitting operation is completed, water is poured into the outfitting dock (60) to make the submerged tube (81) float. Then open the outer dock door (72) and move the immersed tube (81) out of the dock. After the immersed tube (81) is out of the dock, carry out the second outfitting.

5. The prefabrication method according to claim 4, characterized in that, The steel bar binding area (30) of the precast steel bar cage (33) is set outside the dock, and the steel bar cage (33) is moved to the casting platform by a gantry crane.

6. The prefabrication method according to claim 4, characterized in that, The dry dock system also includes a rebar binding dock (20), which serves as a rebar binding area (30). The rebar binding dock (20) is connected to the outfitting dock (60), and an inner dock door (52) is provided between the rebar binding dock (20) and the outfitting dock (60) for connection and disconnection. When the rebar cage (33) is moved, a jacking device (36) is used to push the rebar cage (33) along the shifting track (34) to the casting platform. A bottom frame (35) is provided below the rebar cage (33), and a load trolley (351) is fixedly installed below the bottom frame (35). The load trolley (351) can roll along the shifting track (34).

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