External Connection Bridge for Island Nuclear Power Plant and its Construction Method

Abstract

This invention discloses an external connection bridge for an island nuclear power plant and its construction method. The external connection bridge comprises multiple box girders, each with an internal vehicle passage and a cable laying passage on its top surface. A base assembly for cable laying is located on the top of each box girder, with multiple base assemblies arranged adjacently along the longitudinal direction of the bridge. One end of each base assembly is fixed to a fixed end of one of the box girders, and the other end is mounted on the box girder via a sliding rubber bearing. This invention fully utilizes the structural characteristics of the box girder bridge's top and internal space, matching actual needs and achieving two goals at once. It simultaneously realizes the all-weather traffic capacity and power transmission function required by the island nuclear power plant, significantly reducing construction costs. Furthermore, the base assembly for cable laying on the top of the box girder via sliding rubber bearings effectively isolates the impact of bridge expansion joint deformation on the cables.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power, and in particular relates to a supporting facility for an island nuclear power plant and its construction method. Background Technology

[0002] Nuclear power offers advantages such as being clean and low-carbon, resource-efficient, and economically stable. The site selection and construction of nuclear power plants require comprehensive consideration of factors including geology, water resources, population, meteorology, ecology, and transportation. Choosing relatively remote islands, far from densely populated areas, for nuclear power plants helps increase public acceptance. Furthermore, the favorable water conditions near the islands provide a reliable source of cooling water for the power plant's direct-flow circulation system and favorable conditions for the dispersion of waste heat emissions.

[0003] Establishing reliable transportation links between the island nuclear power plant and the mainland, and enabling the transmission of electricity to the mainland are two major issues that need to be addressed in the construction of island nuclear power plants.

[0004] Due to the special nature and importance of nuclear power plants, transportation links must be able to operate in all weather conditions, including complex marine hydrological and meteorological conditions such as strong winds and heavy fog. Current technologies generally use cross-sea bridges or undersea tunnels as these links. Cross-sea bridges are difficult to construct, require high transportation and lifting capabilities, and necessitate the addition of wind barriers to the bridge deck to ensure passage in adverse weather conditions. Bridge construction is costly, and even in heavy fog and heavy rain, truly all-weather access cannot be guaranteed. Undersea tunnels are unaffected by weather conditions, but their construction costs are exorbitant. Current technologies for transmitting power from island nuclear power plants include submarine cables, overhead lines, power tunnels, and bridge-mounted transmission lines. Except for bridge-mounted transmission lines, all other transmission methods require separate outgoing transmission channels, resulting in high construction costs. Cable laying along the bridge is generally carried out in two ways: either by mounting on the outside of the bridge or by laying inside the box girder. Mounting on the outside of the bridge requires setting up a long cable support tray and maintenance corridor along the longitudinal direction of the bridge, which not only increases construction costs, but also limits the cable carrying capacity due to the space below the bridge deck. Laying inside the box girder has problems such as poor ventilation and heat dissipation and high fire risk, and the carrying capacity is also limited by the space inside the box girder.

[0005] Based on the above analysis, for island nuclear power plants, the existing transportation links still have problems such as the inability to truly guarantee all-weather access and high construction costs. The existing technology for transmitting electricity to the mainland also has problems such as limited cable carrying capacity, poor heat dissipation, and high construction costs. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide an external connection bridge for a nuclear power plant on an island with both all-weather accessibility and power transmission function, and its construction method.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] An external connection bridge for an island nuclear power plant includes multiple box girders. The box girders have a driving passage inside and a cable laying passage on the top surface of the box girders. The top of the box girders is provided with a base assembly for cable laying. Multiple base assemblies are arranged adjacent to each other along the longitudinal direction of the bridge. One end of the base assembly is fixed to a fixed end of one of the box girders, and the other end is mounted on the box girder through a sliding rubber support.

[0009] The external connection bridge for island nuclear power plants of this invention features a precast box girder structure on its superstructure. Outgoing cables are laid on the top surface of the box girder, which offers good ventilation and heat dissipation, and a maintenance passage is provided. The well-concealed interior space of the box girder is used to arrange a two-way traffic lane. This design fully utilizes the structural characteristics of the box girder bridge's top and interior spaces, achieving the all-weather traffic capacity and power outgoing line function required by island nuclear power plants. Furthermore, by installing multi-layer cable trays on top of the base assembly, the cable carrying capacity can be increased, offering significant potential for upward expansion.

[0010] However, when laying cables on top of box girders, the issue of how the cables can adapt to their own thermal expansion and contraction, as well as the expansion, contraction, and vibration of the bridge, needs to be considered. Changes in ambient temperature and load current cause the cables to expand and contract due to heat, a process known as thermal expansion and contraction. The thermomechanical forces generated by the thermal expansion and contraction of the cable core are significant, and the larger the cross-section of the cable core, the greater the resulting thermomechanical forces. These thermomechanical forces cause repeated bending deformation of the cable, leading to fatigue strain in the cable's metal sheath and shortening its service life. Therefore, this invention employs a serpentine laying method to absorb the deformation caused by thermomechanical forces and reduce end thrust, preventing damage to the terminals due to cable displacement. Box girders undergo expansion and contraction deformation under temperature and load conditions. The amount of expansion and contraction is mainly related to the bridge span and structural type, and is generally quite large. If only a conventional serpentine laying method is used, the cable length cannot meet the requirements of bridge expansion and contraction deformation, easily causing excessive bending or stretching of the cable. If this situation occurs repeatedly, it may cause insulation breakdown or even cable breakage. To address the aforementioned issues, this invention incorporates a base assembly for cable laying at the top of the box girder. One end of the base assembly is fixed to the fixed end of the box girder, while the other end is supported on the expansion joint of the box girder via a sliding rubber bearing. The sliding and shear deformation of the sliding rubber bearing allows for relative displacement between the base assembly and the expansion joint, preventing excessive expansion and contraction of the base assembly with the box girder and thus isolating the cable from the impact of bridge expansion joint deformation. The cable is serpentinely installed on the base assembly, requiring only that it meet its own thermal expansion and contraction requirements, eliminating the need for expensive and high-maintenance large-span offset devices. The base assembly is a standardized precast reinforced concrete component, offering advantages such as fast installation, low cost, simple maintenance, and good durability in marine environments. The sliding rubber bearing also provides excellent shock absorption, reducing the impact of bridge vibrations on the cable and ensuring high safety.

[0011] In the aforementioned external connection bridge for the island nuclear power plant, preferably, the base assembly includes multiple movable base plates. One end of the base plate is fixed to a fixed end of a box girder, while the remaining base plates are mounted on the box girder via sliding rubber supports. The base assembly comprises multiple movable base plates, with the base plates at the top of each span of the box girder overlapping each other via mortise and tenon joints. The first base plate is anchored to the fixed end of the box girder by reinforcing steel bars. When the box girder expands or contracts, the sliding rubber supports undergo shear deformation, and each base plate, through the mortise and tenon joints, transmits the tendency of excessive longitudinal expansion and contraction of the box girder to the anchoring end of the first base plate. This prevents the base plates from moving excessively with the box girder, isolating the impact of the box girder's expansion and contraction on the cables. The advantages of using prefabricated, segmented mortise and tenon joints for the base plates also include: 1. Compared to a monolithic design, it effectively controls the size and weight of components, achieving standardized design and factory prefabrication, improving the prefabrication quality of components, and facilitating rapid installation at sea. 2. By dividing the prefabricated base plate into small pieces, each base plate has space for temperature deformation under temperature load. Compared with the whole plate solution, the temperature deformation distribution of the base plate itself is more uniform and has less impact on the cable.

[0012] In the aforementioned external connection bridge for the island nuclear power plant, preferably, each of the aforementioned base components spans across the adjacent box girders in the longitudinal direction. Within this base component spanning the adjacent box girders in the longitudinal direction, one end of the base plate is fixed to a fixed end of one box girder, while the remaining base plates are movably mounted on another box girder via sliding rubber supports. This arrangement prevents excessive expansion and contraction of the base plates with the box girders, isolating the impact of box girder expansion and contraction on the cables. Furthermore, the expansion and contraction directions of each movably connected base plate are opposite to those of the box girder; these opposing expansion and contraction trends partially cancel each other out, further reducing the impact of the base plate's own expansion and contraction and improving the structural stability of the base plate.

[0013] In the aforementioned external connection bridge for the island nuclear power plant, preferably, a mortise and tenon joint assembly is provided at the joint of adjacent base plates. The mortise and tenon joint assembly includes an upper clamp and a lower clamp, with one end of one base plate having the upper clamp and the other end having the lower clamp. This mortise and tenon joint assembly facilitates the assembly of the segmented base plates. Furthermore, adjacent base plates are connected by the upper and lower clamps, with the upper clamp defining the position of the lower clamp. When multiple plates are combined, they mutually constrain each other, which helps improve the structural stability of the base plates.

[0014] In the aforementioned external connection bridge for the island nuclear power plant, preferably, the upper clamping head includes an upper clamping block and an upper clamping slot, and the lower clamping head includes a lower clamping block and a lower clamping slot. The upper clamping block is engaged in the lower clamping slot, and the lower clamping block is engaged in the upper clamping slot. The longitudinal bridge-direction width of the lower clamping slot is greater than the longitudinal bridge-direction width of the upper clamping block, and the longitudinal bridge-direction width of the upper clamping slot is greater than the longitudinal bridge-direction width of the lower clamping block. In a more preferred structure, the upper clamping block and the lower clamping slot are interlocked, and the lower clamping block and the upper clamping slot are interlocked, resulting in better structural stability after overall assembly. The longitudinal bridge-direction width of the lower clamping slot is greater than the longitudinal bridge-direction width of the upper clamping block, and the longitudinal bridge-direction width of the upper clamping slot is greater than the longitudinal bridge-direction width of the lower clamping block, which provides space for the expansion and contraction of adjacent base plates and facilitates the installation of rubber pads.

[0015] In the aforementioned external communication bridge for the island nuclear power plant, preferably, a rubber pad is provided between the upper locking block and the lower locking slot, and a rubber pad is provided between the lower locking block and the upper locking slot. The rubber pad plays a buffering and energy-absorbing role between the upper locking block and the lower locking slot, or between the lower locking block and the upper locking slot.

[0016] In the aforementioned external connection bridge for the island nuclear power plant, preferably, the top of the box girder has embedded steel plates on both sides of the base assembly in the transverse direction. Vertical limiting blocks for restricting the transverse movement of the base assembly are fixed on the embedded steel plates, and transverse limiting blocks for restricting the vertical movement of the base assembly are provided on the top of the vertical limiting blocks. The embedded steel plates can be embedded during the prefabrication of the box girder, and the vertical limiting blocks are welded onto them to restrict the transverse movement of the base plate. The vertical limiting blocks can be set close to the base plate, and each base plate can have one or more vertical limiting blocks. The transverse limiting blocks are horizontally welded to the top of the vertical limiting blocks and are used to press against the top surface of the base plate, restricting the vertical movement of the base plate. Both the vertical and transverse limiting blocks can be made of galvanized steel, limiting excessive transverse and vertical displacement of the base plate and ensuring the safety and stability of the cables and base plate structure under severe weather conditions.

[0017] In the aforementioned external connection bridge for the island nuclear power plant, preferably, the cable is fixed to the base plate using clamps with equal spacing. The clamps can be arranged in a serpentine pattern to restrict the movement of the cable and improve stability.

[0018] In the aforementioned external connection bridge for the island nuclear power plant, preferably, the box girder is a UHPC-steel composite beam. The UHPC-steel composite beam includes an upper UHPC structure and a lower steel structure. The upper UHPC structure includes an integrally formed UHPC top plate, an upper UHPC web plate, and an extension section on the upper UHPC web plate. The UHPC top plate is located between a pair of upper UHPC web plates. The extension section on the upper UHPC web plate and the UHPC top plate form the cable laying channel. The lower steel structure includes a steel bottom plate and a steel lower web plate. The steel bottom plate is located between a pair of lower steel web plates. The upper UHPC web plate is located above the lower steel web plate. The UHPC top plate, upper UHPC web plate, steel bottom plate, and steel lower web plate form the traffic channel.

[0019] The box girder of this invention adopts a composite structure of UHPC and steel: the top plate and the upper part of the web connected to it use UHPC within a certain range, while the bottom plate and the lower part of the web connected to it use steel. Compared to conventional composite box girders, its unique feature is that it uses UHPC as the top plate to bear compressive stress, steel as the bottom plate to bear tensile stress, UHPC in the upper part of the web to bear both compressive and limited tensile stress, and steel in the lower part of the web to bear greater tensile stress. The structure fully utilizes the material properties of steel and UHPC, significantly reducing steel consumption and improving web stability compared to the all-steel web of conventional composite box girders. The self-weight of this UHPC-steel composite girder is approximately 50% of that of a conventional prestressed reinforced concrete box girder, exhibiting lightweight structural characteristics. Simultaneously, UHPC has excellent crack resistance and good structural durability in marine environments, further reducing construction and maintenance costs. Furthermore, due to the light weight of the UHPC-steel composite girder, it can be transported by self-floating and erected as a whole span. After the box girder is prefabricated, steel watertight gates are installed at both ends of the box girder. It is then launched using a slipway or dock, towed by tugboat to the construction area, and finally lifted into place by a floating crane, eliminating the need for transport barges and reducing transportation costs. It has relatively low requirements for lifting capacity, is easy to lift, and allows for fast construction speed, making it suitable for construction in complex offshore conditions.

[0020] The box girder of this invention can be equipped with lighting and ventilation openings on its sidewalls, and the box girder is equipped with necessary lighting, ventilation, and fire protection facilities. The top of the box girder has an extension section on the UHPC web, which is prefabricated together with the UHPC top plate and the UHPC upper web plate. This extension section on the UHPC web can serve as a windbreak wall on top of the box girder, improving the safety of cable laying channels and providing safety protection for inspection personnel. The extension section on the UHPC web is integrally cast with the girder body, reducing offshore operations and eliminating the need for subsequent windbreak wall construction on top of the box girder, effectively shortening the construction period, reducing construction safety risks, and providing good structural integrity and durability.

[0021] Preferably, the aforementioned island nuclear power plant external connection bridge also includes a pier foundation. The box girder is placed on the pier foundation, and a grounding terminal is pre-embedded on the inner side of the extension section of the UHPC web. The first structural main reinforcement in the box girder is connected to the grounding terminal, and the first structural main reinforcement in the box girder is connected to the second structural main reinforcement in the pier foundation. The second structural main reinforcement in the pier foundation extends downward to the seabed for grounding. The cable metal protective layer requires a grounding resistance of no more than 4Ω. Under marine silty geological conditions, the burial depth of grounding facilities is usually more than 20m, resulting in high construction difficulty and cost. Due to the large burial depth of the pile foundation of the pier foundation, the island nuclear power plant external connection bridge of this invention utilizes the structural main reinforcement in the box girder and pier foundation (pier, abutment, pile foundation) to construct a grounding system. A grounding terminal is pre-embedded on the inner side of the windbreak wall, and the cable grounding wire is connected to the pre-embedded grounding terminal. Grounding is then achieved through the first and second structural main reinforcements, eliminating the induced voltage on the cable metal protective layer and eliminating the need for a separate grounding device. This invention directly utilizes the steel reinforcement cage in the box girder and pier foundation to achieve grounding, effectively reducing grounding resistance and achieving potential equalization while significantly reducing costs.

[0022] As a general technical concept, the present invention also provides a construction method for the aforementioned island nuclear power plant external communication bridge, comprising the following steps:

[0023] S1: Prefabricate the box girder and the base assembly; construct the bridge pier foundation at sea;

[0024] S2: Transport the box girder to the installation location, and then hoist the box girder onto the bridge pier foundation;

[0025] S3: Place the base assembly on the box girder, and fix one end of the base assembly to a fixed end of the box girder, while the other end is placed on the top of the box girder through the sliding rubber support. Lay the cable in a serpentine pattern on the base assembly. Construct traffic conditions inside the box girder.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] 1. The external connection bridge for island nuclear power plants of this invention utilizes the top plate of the box girder for cable laying, providing ample overhead space that eliminates the need for cable trays and offers excellent ventilation, heat dissipation, and maintenance conditions. Utilizing the internal space of the box girder as a driving passage eliminates the need for wind barriers, ensuring unaffected traffic by complex weather conditions and truly achieving all-weather traffic capability. This invention fully leverages the structural characteristics of the box girder bridge's top and internal space, matching actual needs and achieving two goals at once: simultaneously fulfilling the all-weather traffic capability and power transmission function required by island nuclear power plants, significantly reducing construction costs.

[0028] 2. The island nuclear power plant external connection bridge of the present invention has a base assembly for cable laying on the top of the box girder through a sliding rubber support, thereby isolating the influence of bridge expansion joint deformation on the cable. The cable is installed in a serpentine manner on the base plate. The cable only needs to meet its own thermal expansion and contraction requirements, without the need to install an expensive large-span offset device.

[0029] 3. The island nuclear power plant external connection bridge of the present invention can also increase the cable carrying capacity by setting up multi-layer cable trays on the base plate, and has great potential for upward expansion. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the external communication bridge for the island nuclear power plant according to the present invention.

[0032] Figure 2 This is a schematic elevation view of the installation locations of the box girder and cables in the external connection bridge of the island nuclear power plant according to the present invention.

[0033] Figure 3 This is a top view of the installation positions of the box girder and cables in the external connection bridge of the island nuclear power plant according to the present invention.

[0034] Figure 4 This is a schematic cross-sectional view of the installation positions of the box girder and cables in the external connection bridge of the island nuclear power plant according to the present invention.

[0035] Figure 5 This is a schematic diagram of the box girder of the external connection bridge for the island nuclear power plant according to the present invention.

[0036] Figure 6 This is a schematic diagram of the stress distribution of the box girder of the external connection bridge for the island nuclear power plant according to the present invention.

[0037] Figure 7 This is a schematic diagram of the grounding structure of the external communication bridge for the island nuclear power plant according to the present invention.

[0038] Legend

[0039] 1. Box girder; 101. Upper UHPC structure; 1011. UHPC top plate; 1012. UHPC upper web plate; 1013. UHPC upper web extension section; 102. Lower steel structure; 1021. Steel bottom plate; 1022. Steel lower web plate; 103. First structural main reinforcement; 2. Base assembly; 201. Base plate; 202. Upper clamp; 2021. Upper clamp block; 2022. Upper clamp slot; 203. Lower clamp; 2031. Lower clamp block; 2032. Lower clamp slot; 204. Rubber pad; 3. Slide-type rubber bearing; 4. Embedded steel plate; 5. Vertical limiting block; 6. Lateral limiting block; 7. Pier foundation; 701. Second structural main reinforcement; 8. Grounding terminal; 100. Driving passage; 200. Cable laying passage. Detailed Implementation

[0040] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0042] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0044] Example:

[0045] like Figures 1-4 As shown, the external connection bridge of the island nuclear power plant in this embodiment includes multiple box girders 1. The box girder 1 has a driving passage 100 inside and a cable laying passage 200 on the top surface of the box girder 1. The top of the box girder 1 is provided with a base assembly 2 for cable laying. Multiple base assemblies 2 are arranged adjacent to each other along the longitudinal direction of the bridge, which can correspond to the number of box girders 1. The base assembly 2 includes multiple movable base plates 201 (such as the four shown in this embodiment, and other base plates 201 can be selected in other embodiments). The base plate 201 at one end of the base assembly 2 is fixed at the fixed end of a box girder 1, and the remaining base plates 201 are set on the box girder 1 by sliding rubber supports 3.

[0046] like Figure 2As shown, in this embodiment, each base assembly 2 is specifically mounted across the adjacent box girder 1 in the longitudinal direction of the bridge. In the base assembly 2 mounted across the adjacent box girder 1 in the longitudinal direction of the bridge, one end of the base plate 201 is fixed at the fixed end of a box girder 1, and the remaining base plates 201 are movably mounted on another box girder 1 through the sliding rubber support 3.

[0047] like Figure 2 As shown in this embodiment, a mortise and tenon joint assembly is provided at the joint of adjacent base plates 201. The mortise and tenon joint assembly includes an upper clamping head 202 and a lower clamping head 203. One base plate 201 has an upper clamping head 202 at one end, and the other base plate 201 has a lower clamping head 203 at one end. The upper clamping head 202 includes an upper clamping block 2021 and an upper clamping groove 2022. The lower clamping head 203 includes a lower clamping block 2031 and a lower clamping groove 2032. The upper clamping block 2021 is engaged in the lower clamping groove 2032, and the lower clamping block 2031 is engaged in the upper clamping groove 2022. The longitudinal width of the lower clamping groove 2032 is greater than the longitudinal width of the upper clamping block 2021, and the longitudinal width of the upper clamping groove 2022 is greater than the longitudinal width of the lower clamping block 2031. A rubber pad 204 is provided between the upper locking block 2021 and the lower locking groove 2032. A rubber pad 204 is provided between the lower locking block 2031 and the upper locking groove 2022.

[0048] like Figure 3 , Figure 4 As shown, in this embodiment, embedded steel plates 4 are pre-embedded on both sides of the transverse bridge direction of the base assembly 2 at the top of the box girder 1. Vertical limiting blocks 5 for restricting the transverse bridge direction movement of the base assembly 2 are fixed on the embedded steel plates 4. A transverse limiting block 6 for restricting the vertical direction movement of the base assembly 2 is provided on the top of the vertical limiting block 5. Both the vertical limiting block 5 and the transverse limiting block 6 can be made of galvanized steel.

[0049] like Figure 3 As shown, the cable is fixed to the base plate 201 using clamps with equal spacing. The clamps can be arranged in a serpentine pattern to restrict the movement of the cable and improve stability.

[0050] like Figure 5As shown, in this embodiment, the box girder 1 is a UHPC-steel composite beam. The UHPC-steel composite beam includes an upper UHPC structure 101 and a lower steel structure 102. The upper UHPC structure 101 includes an integrally formed UHPC top plate 1011, a UHPC upper web plate 1012, and an upper extension section 1013 of the UHPC web plate. The UHPC top plate 1011 is located between a pair of UHPC upper web plates 1012, and the upper extension section 1013 of the UHPC web plate... 1013 and UHPC top plate 1011 form a cable laying channel 200; the lower steel structure 102 includes a steel bottom plate 1021 and a steel lower web plate 1022, the steel bottom plate 1021 is located between a pair of steel lower web plates 1022, and the UHPC upper web plate 1012 is located above the steel lower web plate 1022. The UHPC top plate 1011, UHPC upper web plate 1012, steel bottom plate 1021 and steel lower web plate 1022 form a traffic channel 100.

[0051] like Figure 6 The diagram shows the stress distribution of the UHPC-steel composite beam. As can be seen from the diagram, the top plate 1011 and the upper web 1012 of the UHPC above the neutral axis are under compression, making full use of the compressive strength of the UHPC; the upper web 1012 of the UHPC below the neutral axis is under limited tensile stress, making full use of the tensile strength of the UHPC; the lower web 1022 and the bottom plate 1021 of the steel bear greater tensile stress, making full use of the tensile strength of the steel.

[0052] like Figure 7 As shown, in this embodiment, a bridge pier foundation 7 is also included. The box girder 1 is set on the bridge pier foundation 7. A grounding terminal 8 is pre-embedded on the inner side of the extension section 1013 on the web of the UHPC. The first structural main reinforcement 103 in the box girder 1 is connected to the grounding terminal 8. The first structural main reinforcement 103 in the box girder 1 is connected to the second structural main reinforcement 701 in the bridge pier foundation 7. The second structural main reinforcement 701 in the bridge pier foundation 7 extends downward to the seabed to be grounded.

[0053] The construction method for the external connection bridge of the island nuclear power plant described in this embodiment includes the following steps:

[0054] S1: Precast box girder 1, base assembly 2; bridge pier foundation 7 for offshore construction; during the construction of the above components, construction grounding facilities, such as grounding terminals 8, are pre-embedded simultaneously.

[0055] S2: Transport box girder 1 to the installation position, and then hoist box girder 1 onto the pier foundation 7; box girder 1 is lightweight, so in this embodiment it can be transported by floating and erected as a whole. After the box girder 1 is prefabricated, steel watertight doors are installed at both ends of box girder 1. It is launched by sliding track or dock, and after being towed by tugboat to the construction area, it is hoisted as a whole by floating crane.

[0056] S3: Place the base assembly 2 on the box girder 1, and fix the base plate 201 at one end of the base assembly 2 to the fixed end of the box girder 1. The other base plate 201 at the other end is set on the top of the box girder 1 through the sliding rubber support 3. Lay the cable in a serpentine pattern on the base assembly 2. Construct traffic conditions inside the box girder 1.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A connecting bridge for an island nuclear power plant, comprising multiple box girders (1), characterized in that, The box girder (1) has a driving passage (100) inside, a cable laying passage (200) on the top surface of the box girder (1), a base assembly (2) for cable laying on the top of the box girder (1), and multiple base assemblies (2) are arranged adjacent to each other along the longitudinal direction of the bridge. One end of the base assembly (2) is fixed at the fixed end of a box girder (1), and the other end is set on another adjacent box girder (1) through a sliding rubber support (3). The base assembly (2) includes multiple movable base plates (201). Each base assembly (2) spans across the adjacent box girder (1) in the longitudinal direction. In the base assembly (2) spanning the adjacent box girder (1) in the longitudinal direction, one end of the base plate (201) is fixed to the fixed end of one box girder (1). The remaining base plates (201) are movably mounted on the telescopic end of another adjacent box girder (1) through sliding rubber bearings (3). Through the sliding and shear deformation of the sliding rubber bearings (3), the relative displacement between the base assembly (2) and the telescopic end of another adjacent box girder (1) is realized, preventing the base assembly (2) from telescopically moving with the telescopic end of the box girder (1).

2. The island nuclear power plant external communication bridge according to claim 1, characterized in that, A mortise and tenon joint assembly is provided at the joint of adjacent base plates (201). The mortise and tenon joint assembly includes an upper clamp (202) and a lower clamp (203). One end of one base plate (201) is provided with the upper clamp (202), and the other end of the base plate (201) is provided with the lower clamp (203).

3. The island nuclear power plant external communication bridge according to claim 2, characterized in that, The upper card head (202) includes an upper card block (2021) and an upper card slot (2022), and the lower card head (203) includes a lower card block (2031) and a lower card slot (2032). The upper card block (2021) is engaged in the lower card slot (2032), and the lower card block (2031) is engaged in the upper card slot (2022). The longitudinal bridge width of the lower card slot (2032) is greater than the longitudinal bridge width of the upper card block (2021), and the longitudinal bridge width of the upper card slot (2022) is greater than the longitudinal bridge width of the lower card block (2031).

4. The island nuclear power plant external communication bridge according to claim 2, characterized in that, A rubber pad (204) is provided between the upper card block (2021) and the lower card slot (2032).

5. The island nuclear power plant external communication bridge according to claim 1, characterized in that, The top of the box girder (1) is pre-embedded with pre-embedded steel plates (4) on both sides of the transverse bridge direction of the base assembly (2). The pre-embedded steel plates (4) are fixed with vertical limiting blocks (5) for restricting the transverse bridge direction movement of the base assembly (2). The top of the vertical limiting blocks (5) is provided with transverse limiting blocks (6) for restricting the vertical direction movement of the base assembly (2).

6. The island nuclear power plant external communication bridge according to claim 1, characterized in that, The box girder (1) is a UHPC-steel composite beam, which includes an upper UHPC structure (101) and a lower steel structure (102). The upper UHPC structure (101) includes an integrally formed UHPC top plate (1011), a UHPC upper web plate (1012), and an upper extension section (1013) of the UHPC web plate. The UHPC top plate (1011) is located between a pair of UHPC upper web plates (1012). The upper extension section (1013) of the UHPC web plate and the UHPC The top plate (1011) encloses the cable laying channel (200); the lower steel structure (102) includes a steel bottom plate (1021) and a steel lower web plate (1022), the steel bottom plate (1021) is located between a pair of steel lower web plates (1022), the UHPC upper web plate (1012) is located above the steel lower web plate (1022), and the UHPC top plate (1011), UHPC upper web plate (1012), steel bottom plate (1021) and steel lower web plate (1022) enclose the driving channel (100).

7. The island nuclear power plant external communication bridge according to claim 6, characterized in that, It also includes a pier foundation (7), the box girder (1) is set on the pier foundation (7), and a grounding terminal (8) is pre-embedded on the inner side of the extension section (1013) on the web of the UHPC. The first structural main reinforcement (103) in the box girder (1) is connected to the grounding terminal (8), and the first structural main reinforcement (103) in the box girder (1) is connected to the second structural main reinforcement (701) in the pier foundation (7). The second structural main reinforcement (701) in the pier foundation (7) extends downward to the seabed to be grounded.

8. A construction method for an external communication bridge for an island nuclear power plant as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Prefabricate the box girder (1) and the base assembly (2); construct the bridge pier foundation (7) at sea. S2: Transport the box girder (1) to the installation position, and then hoist the box girder (1) onto the bridge pier foundation (7); S3: Place the base assembly (2) on the box girder (1) and fix one end of the base assembly (2) to a fixed end of the box girder (1), and set the other end on the top of the box girder (1) through the sliding rubber support (3), and lay the cable in a serpentine pattern on the base assembly (2); construct the conditions for vehicle passage inside the box girder (1).

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