Steel tube concrete arch rib structure and construction method

Abstract

The application provides a steel pipe concrete arch rib structure and a construction method, steel arch foot filling steel fiber concrete is filled in both ends of the steel arch, after the steel arch is connected, concrete prefabricated units and slurry are filled in the arch rib steel pipe in the middle arch section; the prefabricated unit comprises a regular hexagon A prefabricated block designed with minimum cross-section porosity and minimum prefabricated block type and a B prefabricated block filled in the gap between the overall outer contour of the multi-layer A prefabricated block communication honeycomb layer stack and the inner wall of the arch rib steel pipe, a manhole and a temporary operation platform are arranged on the arch rib steel pipe, the prefabricated block is pressed and formed in a factory and is hoisted to the operation platform, is lowered through the manhole and is transported to an installation position, precise positioning is achieved through an in-pipe installation robot, the arrangement is performed in a cross-section adaptive division mode, longitudinal staggered laying is performed, finally, a vacuum assisted segmented pressure grouting process is adopted, slurry is injected into each pore, and the steel pipe concrete arch rib construction is completed. The problems of large volume shrinkage of the concrete body, easy voiding and low construction efficiency of the concrete body under the highland large temperature difference environment are solved.

Description

Technical Field

[0001] This invention relates to the field of concrete construction technology for arch bridges, and in particular to a steel-concrete composite arch rib structure and its construction method. Background Technology

[0002] In existing steel-concrete composite arch bridge construction, differentiated construction techniques are often employed for different sections of the arch rib steel pipe. The horizontal section at the arch foot typically uses high-strength, self-compacting, shrinkage-compensating concrete with added steel fibers for conventional pouring. The remaining steel pipe sections generally utilize a vacuum-assisted multi-stage relay jacking process. This involves a multi-stage pumping system to inject concrete in stages from low to high elevations, combined with vacuum technology to reduce air bubbles within the pipes, thus ensuring the concrete's density. This type of construction requires steel-concrete composites that meet high-strength, self-compacting requirements, resulting in a relatively high amount of cementitious materials. Furthermore, the construction process relies on on-site pumping equipment, and after the concrete jacking is completed, it must wait for its strength to reach the design standard before subsequent procedures can proceed, leading to a longer overall construction period.

[0003] The aforementioned traditional construction methods have many technical shortcomings in practical applications and are difficult to adapt to the needs of complex construction environments: the large volume of concrete poured in a single steel pipe makes each pouring operation time-consuming; in the high-altitude environment with large temperature differences, the workability of concrete deteriorates rapidly, and the volume shrinkage is much greater than in plains areas, significantly increasing the difficulty of controlling the stability of concrete workability; at the same time, high-strength concrete, due to its high content of cementitious materials, has a large heat release of hydration and is prone to large temperature deformation; in addition, the limited on-site construction and transportation conditions, affected by environmental factors such as large temperature differences and strong radiation, are prone to quality problems such as pump blockage, incoordination between concrete and steel pipe deformation, and voids in the concrete inside the pipe. Furthermore, the effective construction period is limited, and the need for equal-strength curing of concrete after jacking further prolongs the construction cycle and reduces the overall operation efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide a steel-concrete composite arch rib structure and construction method to solve the problems of large volume shrinkage and easy voiding of jacking and pouring concrete under the large temperature difference environment of plateau, and low construction efficiency.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a steel-concrete composite arch rib structure, wherein the arch feet of the tension sections at both ends of the steel arch are filled with steel fiber concrete, and the middle arch section of the steel arch is an arch rib steel pipe filled with precast concrete units. The prefabricated unit includes prefabricated block A and prefabricated block B. Prefabricated block A has a regular hexagonal cross section. On the radial cross section of the arch rib steel pipe, prefabricated block A is arranged in a concentric honeycomb layer at the center of the arch rib steel pipe. Several equal prefabricated blocks B fill the gap between the overall outer contour of the multi-layer prefabricated block A and the inner wall of the arch rib steel pipe. On the longitudinal section of the arch rib steel pipe, the precast concrete units of two adjacent vertical layers are arranged in a staggered manner. Inter-block joints are provided between adjacent A precast blocks and between A precast blocks and B precast blocks. Hole wall gaps are provided between precast units and the inner wall of steel pipes. Cross-sectional gaps are provided between adjacent precast units in the longitudinal direction of the arch rib steel pipe. Grout fills the hole wall gaps, inter-block joints and cross-sectional gaps.

[0006] In the preferred embodiment, the cross-sectional dimensions and arrangement of precast blocks A and B are set as follows: It can ensure that the cross-section of the arch rib steel pipe is fully filled, the cross-section porosity meets the load-bearing capacity and durability requirements of the steel pipe concrete arch rib structure and is minimized as much as possible, and the types of precast concrete blocks are simplified. The side length of the regular hexagon of the precast block is determined by adapting it to the inner diameter of the arch rib steel pipe.

[0007] In the preferred embodiment, a first protrusion point is provided at the midpoint of each of the three adjacent sides of the regular hexagon of precast block A, and the height of the first protrusion point is equal to the width of the gap between the precast blocks; A second protruding point is provided at the center of one end face of precast block A. The height of the second protruding point is equal to the width of the longitudinal section gap of the precast block.

[0008] A construction method for a steel-concrete composite arch rib structure, the method comprising: S1. Complete the pouring of steel fiber reinforced concrete at the arch foot of the arch bridge and the closure of the steel arch. Install several manholes on the arch rib steel pipe and set up a temporary working platform. S2. Divide the cross-section of a single steel pipe into several prefabricated units according to the cross-sectional dimensions of the arch rib steel pipe, calculate the reserved hole wall gap and the inter-block gap, and press the prefabricated blocks in the factory. S3. Transport the precast blocks to the temporary working platform next to the arch rib steel pipe, lower the precast blocks into the arch rib steel pipe through the manhole and transport them to the installation position. S4. Using an in-pipe installation robot, each precast block is precisely positioned along the pipe wall, arranged in a staggered manner in the longitudinal direction, and a cross-sectional gap is reserved to complete the laying and installation of all precast blocks inside the steel pipe. S5. Vacuum-assisted grouting process is used for the arch rib steel pipe after the precast blocks have been installed. Grout is injected into the gaps between the hole walls, the gaps between blocks, and the gaps in the cross section along the axial direction of the arch rib of the steel pipe in several sections to complete the grouting construction inside the steel pipe.

[0009] In the preferred embodiment, manholes are spaced along the length of the arch rib steel pipe, and the placement of the manholes is adapted to the grouting segmentation of the arch rib steel pipe. The diameter of the manholes meets the requirements for the placement of precast blocks and the operation inside the pipe. Each precast block is made of low water-cement ratio concrete and is pressed into shape in the factory, with shrinkage rate controlled during the molding process.

[0010] In the preferred embodiment, in step S3, towers are installed on the sides of the arch feet at both ends of the arch bridge, and the cables are suspended above the arch bridge through the towers. Precast blocks are hoisted from the arch foot of the arch bridge to the corresponding temporary working platform on the arch bridge using cable cranes. Auxiliary handling equipment then moves the precast blocks from the temporary working platform through manholes to the pipe transport vehicle inside the arch rib steel pipe. A winch lowers the pipe transport vehicle to the working face via wire rope to dock with the robot installed inside the pipe.

[0011] In the preferred embodiment, in step S4, the precast blocks are stacked vertically from bottom to top inside the arch rib steel pipe. Precast block A is placed with all three first protrusions facing downwards, so that the adjacent precast blocks are supported by the first protrusions to form a uniform inter-block gap. The outer B precast blocks are arranged in close contact with the adjacent A precast blocks and are stacked layer by layer synchronously with the A precast blocks. The side walls of the B precast blocks are adapted to the outer walls of the A precast blocks and the inner walls of the arch rib steel pipes.

[0012] In the preferred embodiment, in step S4, when the precast blocks are laid vertically layer by layer along the arch rib steel pipe, the precast blocks in adjacent layers are arranged with longitudinal staggered joints, and the width of the staggered joints is adapted to the length of the precast blocks. The second protruding points of precast blocks A are arranged in the same direction, so that the longitudinally adjacent precast blocks in the same layer form a uniform cross-sectional gap.

[0013] In the preferred embodiment, in step S5, before grouting, the gap cavity of the precast block inside the arch rib steel pipe is first vacuumed to create a negative pressure environment inside the cavity to remove air. During the grouting process, the grout, under the combined action of negative pressure and grouting pressure, uniformly fills the gaps in the hole walls, the joints between blocks, and the cross-sectional gaps.

[0014] In the preferred scheme, the arch rib steel pipe is divided into multiple grouting sections along its axial direction and implemented sequentially. The division of each grouting section is adapted to the axial laying unit of the precast block and the location of the manhole. After a single grouting section is completed, the next grouting section is carried out. The grout in adjacent grouting sections is tightly connected to ensure the integrity of the grouting of the entire pipe section.

[0015] This invention provides a steel-concrete composite arch rib structure and its construction method. It employs a construction approach combining prefabrication and vacuum grouting, transferring the core concrete forming process to a controlled factory environment. This significantly reduces the shrinkage and deformation of the prefabricated blocks. Combined with vacuum-assisted grouting, it improves the density of gap filling, reduces the probability of voids within the pipe, and effectively optimizes the structural forming quality. The fluidity and uniformity of the grout are ensured, improving the bond between the concrete and the steel pipe wall and enhancing the overall stability of the structure.

[0016] The construction process utilizes automated installation equipment inside the pipe to replace traditional high-altitude and manual operations within the pipe, reducing on-site construction safety risks, simplifying on-site construction procedures, shortening critical path construction time, expanding the applicable construction period, and improving overall construction efficiency. Construction procedures no longer require prolonged waiting for concrete strength development, accelerating the transition between procedures and adapting to the pace of construction in complex environments.

[0017] The amount of hydration grout used inside the pipe is significantly reduced, effectively lowering the hydration temperature rise, controlling the magnitude of structural volume deformation, reducing the possibility of temperature cracks, and enhancing the structural stress coordination and long-term service performance. Effective control of structural volume deformation improves the deformation coordination between concrete and steel pipes, enhancing the structure's adaptability to complex environments.

[0018] The process reduces issues such as pump blockage and incoordination between concrete and steel pipe deformation, lowering post-construction defect handling costs. The precast blocks feature simplified specifications, reducing the variety of irregularly shaped blocks, simplifying mold processing and on-site sorting and installation, and improving construction convenience. The overall construction process exhibits enhanced stability and improved comprehensive benefits, making it suitable for complex engineering environments such as high-altitude areas with large temperature differences and strong winds, while balancing structural performance, construction efficiency, and economy. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is an elevation view of the overall structure of the arch bridge of this invention; Figure 2 This is a structural diagram of the arrangement of precast blocks for the arch rib steel pipe section of the present invention; Figure 3 This is a stacking structure diagram of prefabricated block A of the present invention; Figure 4 This is a structural diagram of the longitudinal arrangement of the prefabricated blocks of the present invention; Figure 5 This is a schematic diagram of the precast blocks of the present invention being transferred into the arch rib steel pipe; Figure 6 This is a schematic diagram of the internal transportation of precast blocks in the tube according to the present invention; Figure 7 This is a schematic diagram of the prefabricated block tube installation of the present invention.

[0020] In the diagram: 1. Arch rib steel pipe; 101. Hole wall gap; 102. Block joint; 103. Cross-sectional joint; 2. Manhole; 3. Temporary work platform; 4. Precast block A; 401. First protruding point; 402. Second protruding point; 5. Precast block B; 6. Tower; 7. Cable crane; 8. Auxiliary handling equipment; 9. Pipe transport vehicle; 10. Pipe installation robot; 11. Winch; 12. Wire rope; 13. Arch foot. Detailed Implementation

[0021] Example 1 like Figure 1-7 As shown, a steel-concrete composite arch rib structure is provided, wherein the arch feet 13 of the tension sections at both ends of the steel arch are filled with steel fiber reinforced concrete, and the middle arch section of the steel arch is an arch rib steel pipe 1 filled with precast concrete units. The prefabricated unit includes A prefabricated block 4 and B prefabricated block 5. The cross section of A prefabricated block 4 is a regular hexagon. On the radial cross section of the arch rib steel pipe 1, A prefabricated block 4 is arranged in a concentric honeycomb layer at the center of the arch rib steel pipe 1. Several equal B prefabricated blocks 5 fill the gap between the overall outer contour of the multi-layer A prefabricated block 4 and the inner wall of the arch rib steel pipe 1. On the longitudinal section of the arch rib steel pipe 1, the precast concrete units of two adjacent vertical layers are arranged in a staggered manner. Inter-block gaps 102 are provided between adjacent A precast blocks 4 and between A precast blocks and B precast blocks 5. Hole wall gaps 101 are provided between the precast units and the inner wall of the steel pipe. Cross-sectional gaps 103 are provided between adjacent precast units in the longitudinal direction of the arch rib steel pipe 1. Grout is filled in the hole wall gaps 101, inter-block gaps 102 and cross-sectional gaps 103.

[0022] In the preferred embodiment, the cross-sectional dimensions and arrangement of precast block A 4 and precast block B 5 are set as follows: It can ensure that the cross-section of the arch rib steel pipe 1 is fully filled, the cross-section porosity meets the load-bearing capacity and durability requirements of the steel pipe concrete arch rib structure and is minimized as much as possible, and the types of precast concrete blocks are simplified. The side length of the regular hexagon of precast block 4 is determined by adapting it to the inner diameter of the arch rib steel pipe 1.

[0023] In the preferred embodiment, a first protrusion point 401 is provided at the midpoint of each of the three adjacent sides of the regular hexagon of precast block A 4, and the height of the first protrusion point 401 is equal to the width of the gap 102 between the precast blocks. A second protruding point 402 is provided at the center of one end face of precast block 4. The height of the second protruding point 402 is equal to the width of the longitudinal section gap 103 of the precast block.

[0024] This application adopts a structure where the arch foot 13 and the intermediate arch rib are constructed separately. Arch foot 13, as the endpoint of the steel-concrete composite arch bridge and the tension anchor point of the stay cables, is the most complex and critical stress area in terms of the entire bridge's mechanical behavior. It must simultaneously withstand vertical reaction forces, horizontal thrust, and localized concentrated tensile forces generated by the stay cable tensioning, placing extremely high demands on the material's crack resistance, fatigue resistance, and deformation coordination capabilities. Therefore, instead of using a precast block grouting scheme for the main arch rib, this area employs on-site casting of steel fiber reinforced concrete. This effectively limits crack propagation, improves tensile strength and ductility, meets the requirements for joint deformation coordination, ensures tight bonding with the steel pipe wall and stay cable anchors to transfer stress, and avoids stress concentration and durability risks caused by precast block splicing gaps. In the intermediate section, construction has been adapted to the engineering environment, reconstructing the traditional on-site casting mode of concrete within the steel pipe into a precast assembly mode. This overall approach is suitable for the complex engineering environment of steel-concrete composite construction, including high-altitude areas with large temperature differences, high-altitude restrictions, and strong winds.

[0025] In this scheme, precast block A 4 adopts a regular hexagonal cross section, which is a dual choice based on the optimality of planar close-lay geometry and the adaptability of circular cross section filling. It is also the core geometric basis for achieving the minimum cross section void ratio, the fewest types of precast blocks, and the maximum value of side length.

[0026] In plane geometry, the regular hexagon is the only equilateral convex polygon that can achieve a completely tessellated surface without gaps or overlaps. Compared with the tessellation patterns of quadrilaterals and triangles, the total length of the boundary of the regular hexagonal tessellation is the shortest, and the internal redundant gaps are the fewest under the same filling area. Geometrically, this determines that the cross-sectional void ratio can be reduced to the minimum after filling.

[0027] To accommodate the circular cross-section of the arch rib steel pipe 1, the A precast block 4 adopts a concentric honeycomb layered arrangement pattern. Taking the central single A precast block as the reference, it is arranged in a ring shape outward layer by layer. The number of blocks in each layer increases according to a fixed rule, forming a multi-layer symmetrical honeycomb array. This arrangement allows the overall outer contour to present an approximately circular symmetrical shape, which fits the arc surface of the inner wall of the arch rib steel pipe 1 to the greatest extent.

[0028] The side length of precast block 4 and the inner diameter of arch rib steel pipe 1 are designed with constraint adaptation. Under the premise of not adding new types of precast blocks and ensuring the minimum void ratio, the side length value is maximized: the side length must meet the requirement that after the honeycomb array is arranged, the gap area between the outer contour of the array and the inner wall of the steel pipe is evenly distributed along the circumference and the geometric shape is completely equal. At the same time, the larger the side length, the larger the coverage area of ​​a single precast block 4, and the smaller the total number of blocks required, which can simplify the mold processing and on-site installation process.

[0029] The arrangement of precast blocks A follows a layered quantity constraint law. The central block is the base layer, and the number of blocks increases by a fixed difference for each additional layer. After multiple layers are arranged, the total number conforms to the quantity logic of honeycomb tiling. The number of blocks in the outermost layer is exactly equal to the number of gap areas. This geometric constraint ensures that the shape and size of all gap areas are completely consistent. Only a single specification of precast block B5 is needed to fill all gaps, minimizing the types of precast blocks and avoiding the processing, sorting, and installation errors caused by multiple specifications of irregularly shaped blocks.

[0030] By combining four major geometric conditions—hexagonal close-packing, concentric honeycomb layered arrangement, side length constraint adaptation, and symmetrical gap equality—this scheme achieves the comprehensive design goals of maximizing filling fullness, minimizing void ratio, ensuring unique precast block types, and maximizing block size within a circular steel pipe cross-section. This solves the problems of large shrinkage and difficult construction of irregularly shaped components in traditional cast-in-place concrete.

[0031] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-7 The structure shown illustrates a construction method for a steel-concrete composite arch rib structure, the method comprising: S1. Complete the pouring of steel fiber reinforced concrete at the arch foot of the arch bridge and the closure of the steel arch. Install several manholes 2 on the arch rib steel pipe 1 and set up a temporary working platform 3. S2. Divide the cross-section of a single steel pipe into several prefabricated units according to the cross-sectional dimensions of the arch rib steel pipe 1, calculate the reserved hole wall gap 101 and the block gap 102, and press the prefabricated blocks in the factory. S3. Transport the precast blocks to the temporary work platform 3 next to the arch rib steel pipe 1, lower the precast blocks into the arch rib steel pipe 1 through the manhole 2 and transport them to the installation position. S4. The in-pipe installation robot 10 is used to accurately position each precast block along the pipe wall, arrange them in a staggered manner in the longitudinal direction, and leave a cross-sectional gap 103 to complete the laying and installation of all precast blocks in the steel pipe. S5. Vacuum-assisted grouting process is used to inject grout into the gaps 101 between the holes, the gaps 102 between the blocks and the gaps 103 in the cross section along the axial direction of the arch rib of the steel pipe in several sections to complete the grouting construction inside the steel pipe.

[0032] This embodiment adopts an integrated construction approach of factory prefabrication, in-pipe assembly, and vacuum grouting. Relying on the coordinated operation of high-altitude hoisting, in-pipe transportation, automated installation, and segmented grouting equipment, the entire construction process of the arch foot 13 structure construction, prefabricated block preparation and transportation, precise in-pipe positioning and assembly, and gap sealing and filling is completed in sequence. The traditional on-site concrete casting mode inside steel pipes is reconstructed into a prefabrication and assembly mode, and the core construction process is transferred to a controllable environment. This method optimizes the traditional construction logic from the dual dimensions of structural design and construction technology. Through the combination of geometrically optimized block assembly and refined grouting, the structural quality, construction efficiency, safety management, and economic benefits are improved simultaneously.

[0033] This construction method relies on the prefabricated block factory molding and precise assembly to optimize the structural forming quality, reduce concrete shrinkage deformation, and ensure dense gap filling by vacuum grouting technology, eliminating the risk of voids inside the pipes. It employs automated robotic installation inside the pipes to replace manual labor at heights, improving construction safety and overall work efficiency, and overcoming seasonal and climatic limitations to achieve continuous construction throughout the year. By significantly reducing the amount of hydration grout used inside the pipes, it effectively controls the hydration temperature rise and volume deformation, eliminating structural hazards caused by temperature cracks. The overall process avoids construction failures such as pipe blockage and voids that are common in traditional cast-in-place processes, reducing later troubleshooting and maintenance costs, and achieving excellent comprehensive economic benefits while ensuring the long-term performance of the structure.

[0034] In the preferred embodiment, manholes 2 are arranged at intervals along the length of the arch rib steel pipe 1. The arrangement of manholes 2 is adapted to the grouting segmentation position of the arch rib steel pipe 1. The diameter of manholes 2 meets the requirements for the placement of precast blocks and the operation inside the pipe. Each precast block is made of low water-cement ratio concrete and is pressed into shape in the factory, with shrinkage rate controlled during the molding process.

[0035] In the preferred embodiment, in step S3, towers 6 are installed on the sides of the arch feet 13 at both ends of the arch bridge, and the cable suspension 7 is installed above the arch bridge through the towers 6; The precast blocks are hoisted from the arch foot 13 of the arch bridge to the corresponding temporary work platform 3 on the arch bridge by cable crane 7. The auxiliary handling equipment 8 transports the precast blocks on the temporary work platform 3 through the manhole 2 to the pipe transport vehicle 9 inside the arch rib steel pipe 1. The winch 11 pulls the pipe transport vehicle 9 down to the work surface through the wire rope 12 to dock with the pipe installation robot 10.

[0036] The precast block transportation system adopts a two-stage transportation mode that combines high-altitude hoisting with in-pipe transfer. The tower 6 and cable crane 7 form a high-altitude hoisting unit, which is suitable for the high-altitude and long-distance transportation needs of large-span arch bridges. It can stably hoist precast blocks from the ground arch foot 13 to the temporary working platform 3 on the arch, avoiding the interference of high-altitude winds and large temperature differences on high-altitude transportation.

[0037] The auxiliary handling equipment 8 is equipped with a multi-degree-of-freedom robotic arm, which can perform multi-dimensional movements such as horizontal rotation, pitch, extension, and fine adjustment. It can perform clamping, turning, and lowering of precast blocks in the narrow manhole 2, solving the problems of limited space and narrow transfer paths on the aerial work platform. The pipe transport vehicle 9 is pulled by a winch 11 and a wire rope 12, and adopts constant speed traction control. It can move smoothly inside the arc-shaped steel pipe, avoiding sudden stops and starts that could cause damage to the precast blocks.

[0038] The in-pipe installation robot 10 integrates a multi-degree-of-freedom robotic arm and a negative pressure suction cup connector. The negative pressure suction cup achieves non-damaging clamping of precast blocks through vacuum adsorption, adapting to the smooth surface of the precast blocks and avoiding edge damage caused by mechanical clamping. The multi-degree-of-freedom robotic arm can achieve precise alignment, angle fine adjustment, and jacking fixation in three-dimensional space. It can complete the layered, staggered, and fitting installation of A and B precast blocks inside the closed steel pipe without the need for personnel to enter the pipe, realizing unmanned high-altitude in-pipe operations and improving installation accuracy and construction safety.

[0039] In the preferred embodiment, in step S4, the precast blocks are stacked vertically from bottom to top inside the arch rib steel pipe 1, and the A precast block 4 is placed with all three first protrusion points 401 facing downwards, so that the adjacent precast blocks are supported by the first protrusion points 401 to form a uniform inter-block gap 102. The outer B precast block 5 is attached to the adjacent A precast block 4 and is stacked layer by layer synchronously with the A precast block 4. The side wall of the B precast block 5 is adapted to the outer wall of the A precast block 4 and the inner wall of the arch rib steel pipe 1.

[0040] In the preferred embodiment, in step S4, when the precast blocks are laid vertically layer by layer along the arch rib steel pipe 1, the precast blocks in adjacent layers are arranged with longitudinal staggered joints, and the width of the staggered joints is adapted to the length of the precast blocks. The second protruding point 402 of precast block 4 is arranged in the same direction, so that a uniform cross-sectional gap 103 is formed between longitudinally adjacent precast blocks in the same layer.

[0041] The first protruding point 401 and the second protruding point 402 set on the precast block 4 are the core design of the gap size self-constraint: the first protruding point 401 is used for lateral support between blocks, and its height matches the width of the gap 102 between blocks. When the blocks are stacked, the first protruding point 401 directly abuts against the adjacent blocks. Without manual measurement or tooling positioning, it can ensure that the gap between blocks is uniform and avoid the problem of local excessive width or narrowness when the grout is filled; the second protruding point 402 is used for axial end face positioning, which limits the width of the cross-sectional gap 103 and ensures that the longitudinal grouting channel is continuous and unobstructed.

[0042] Precast block 4 is stacked with the first protrusion 401 facing downwards. Gravity allows the protrusion to stably abut against the block. Combined with the fit and limiting of precast block 5, precast block 4, and the inner wall of the steel pipe, a self-locking stacking structure is formed to prevent the blocks from shifting or tilting during installation and grouting.

[0043] The longitudinal staggered joint arrangement is not randomly set, but is an optimized design based on the axial stress characteristics of the arch rib steel pipe 1: the staggered joint arrangement can disperse the concentrated stress in the axial direction of the steel pipe to the splicing points of different blocks, avoid the formation of a weak section in the structure by the continuous splicing joint, and the width of the staggered joint is adapted to the length of the precast block, which not only ensures the stress dispersion effect, but also does not destroy the symmetry of the block arrangement, while allowing the grout to flow smoothly along the staggered joint channel, ensuring that the entire cross section is filled densely.

[0044] In the preferred embodiment, in step S5, before grouting, the gap cavity of the precast block inside the arch rib steel pipe 1 is first vacuumed to create a negative pressure environment inside the cavity to remove air. During the grouting process, the grout uniformly fills the gaps 101 in the hole wall, the gaps 102 between blocks, and the gaps 103 in the cross section under the combined action of negative pressure and grouting pressure.

[0045] In the preferred scheme, the arch rib steel pipe 1 is divided into multiple grouting sections along its axial direction and implemented sequentially. The division of each grouting section is adapted to the axial laying unit of the precast block and the layout position of the manhole 2. After a single grouting section is completed, the next grouting section is carried out. The grout in adjacent grouting sections is tightly connected to ensure the integrity of the grouting of the entire pipe section.

[0046] The core of vacuum-assisted grouting is the synergistic effect of negative pressure degassing and pressure filling. Before grouting, a vacuum is drawn into all the gaps and cavities inside the steel pipe to form a negative pressure environment, which can completely remove air and residual impurities from the gaps 101 in the borehole wall, the gaps 102 between blocks, and the gaps 103 in the cross section, eliminating the defects of air bubbles wrapped in grout and local voids. This is also a key process optimization to adapt to the low-pressure environment of high altitude.

[0047] During grouting, the external grouting pressure and the negative pressure inside the pipe create a pressure difference, propelling the grout to fill all gaps at a uniform flow rate. Compared to traditional self-flowing grouting, this pressure difference allows the grout to penetrate even the smallest gaps, ensuring complete filling without dead zones. The segmented grouting is adapted to the location of manhole 2 and the axial laying unit of the precast blocks. Each segment is an independent grouting unit. Continuous grouting in a single segment can avoid the formation of cold joints during the initial setting of the grout. Adjacent grouting segments adopt a connecting grouting process to ensure the integrity of the grout. At the same time, segmented grouting can control the amount of grout used in a single operation, reduce the risk of concentrated release of grout hydration heat, reduce temperature deformation and shrinkage cracking, and adapt to the construction requirements of high-altitude environments with large temperature differences.

[0048] Example 3 Further explanation is provided in conjunction with Examples 1 and 2, such as... Figure 1-7The structure shown in this embodiment is a specific engineering implementation of the steel-concrete composite arch rib structure and construction method described in Embodiments 1 and 2. It is designed for a 500m main span, upper-bearing steel-concrete composite arch bridge with a rise of 105m and an arch rib steel pipe diameter of 1.6m. In this embodiment, four manholes 2 are arranged on a single pipe, with a manhole diameter of 600mm. Considering the special construction environment of high altitude, large temperature difference, strong wind, and low air pressure in the plateau region, the configuration, quantity, spacing, and grouting process parameters of the precast blocks were specifically determined. All parameters were based on the core principles of cross-sectional filling efficiency, structural stress stability, and adaptability to plateau construction, strictly following the geometric constraints and process logic of Embodiments 1 and 2. This represents a practical application of a general construction method.

[0049] The arch rib steel pipe 1 section is filled with a combination of precast blocks A (4 blocks) and B (5 blocks). Precast blocks A (4 blocks) are hexagonal in cross-section, arranged in a concentric honeycomb layered pattern, totaling 19 blocks. The arrangement consists of 1 block in the center, 6 in the inner layer, and 12 in the outer layer. The core principle behind determining the three-layer concentric honeycomb arrangement of precast blocks A is: firstly, considering the circular cross-section diameter of the arch rib steel pipe 1, the three-layer arrangement maximizes the side length of the hexagonal A-type precast blocks without increasing the number of block types, reducing the total number of precast blocks and simplifying the factory prefabrication and on-site installation process; secondly, the three-layer honeycomb... The outer contour of the trough array can form 12 gap areas with completely identical geometric shapes and sizes with the inner wall of the circular steel pipe, ensuring that only a single type of B precast block is needed to complete the filling, thus minimizing the types of precast blocks; thirdly, the three-layer arrangement can precisely control the total space of the cross-sectional gap, keeping the volume ratio of the grout inside the pipe at a low design ratio, which not only reserves a continuous and unobstructed grouting channel to ensure dense filling of the grout, but also strictly controls the volume of hydration grout to avoid problems such as concentrated hydration heat and excessive volume shrinkage caused by excessive grout, perfectly adapting to the temperature control and crack resistance requirements of the high-altitude environment with large temperature differences.

[0050] The outer contour of the three-layer A precast block 4 and the inner wall of the arch rib steel pipe 1 form 12 uniform and symmetrical gaps, which are filled by 12 equal B precast blocks 5. This quantity ratio can simplify mold processing and on-site sorting and installation to the greatest extent. Only two sets of molds are needed to complete the production of all blocks.

[0051] In this embodiment, the preferred hexagonal side length of precast block A 4 is 179mm, its height on the circular cross-section is 310mm, and its total cross-sectional area S is... A=0.0832㎡. Precast block B 5 is an irregularly shaped component, approximately trapezoidal in shape. Its bottom edge and one of its side edges correspond to the side length of the regular hexagon of precast block A 4, both being 179mm. During installation, they are aligned and abutted against each other. The other side edge is the shortest edge, its length being the distance between the outer contour of the three layers of precast blocks A 4 and the apex of precast block A to the inner wall of the arch rib steel pipe 1. The top edge of precast block B 5 is an arc segment adapted to the inner wall of the arch rib steel pipe 1. During assembly, the shortest edges of two adjacent precast blocks B 5 are aligned pairwise, and their bottom edges and one of their side edges are respectively attached to the three adjacent precast blocks A 4. The area S of precast block B 5 is... B =0.0262㎡.

[0052] In this embodiment, the preferred hole wall gap 101 is 10mm, that is, the distance between the overall outer contour formed by assembling precast block 4 and precast block 5 and the inner wall of arch rib steel pipe 1 is 10mm; the inter-block gap 102 is 5mm, and the cross-sectional gap 103 is 5mm.

[0053] For an arch-ribbed steel pipe with a diameter of 1.6m and a cross-sectional area of ​​S=2㎡, the slurry ratio of the cross-section is... The grouting area is 0.11㎡.

[0054] Along the axial length of the arch rib steel pipe 1, precast blocks A 4 and B 5 are each 500mm long, and the weight of a single precast block A 4 is 104kg, which is adapted to the load limit of each transport component in the scheme.

[0055] In this embodiment, the preferred longitudinal staggered arrangement has a staggered joint rate of 20%, that is, the cross sections of two adjacent precast blocks are staggered by 100mm.

[0056] The grouting process is carried out in multiple sections along the axial direction of the arch rib steel pipe 1. The volume of grouting in a single grouting is about 10 cubic meters. A single arch rib is grouted in 5 stages. The total volume of grouting for the 8 steel pipes of the entire bridge is about 400 cubic meters.

[0057] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A steel-concrete composite arch rib structure, characterized in that: The arch feet (13) of the tension section at both ends of the steel arch are filled with steel fiber reinforced concrete, and the middle arch section of the steel arch is an arch rib steel pipe (1) filled with precast concrete units. The prefabricated unit includes prefabricated block A (4) and prefabricated block B (5). The cross section of prefabricated block A (4) is regular hexagonal. On the radial cross section of the arch rib steel pipe (1), prefabricated block A (4) is arranged in a concentric honeycomb layer at the center of the arch rib steel pipe (1). Several equal prefabricated blocks B (5) fill the gap between the overall outer contour of the multi-layer prefabricated block A (4) and the inner wall of the arch rib steel pipe (1). On the longitudinal section of the arch rib steel pipe (1), the precast concrete units of two adjacent vertical layers are arranged in a staggered manner. Inter-block gaps (102) are provided between adjacent A precast blocks (4) and between A precast blocks and B precast blocks (5). Hole wall gaps (101) are provided between the precast units and the inner wall of the steel pipe. Cross-sectional gaps (103) are provided between the longitudinally adjacent precast units of the arch rib steel pipe (1). Grout is filled in the hole wall gaps (101), inter-block gaps (102) and cross-sectional gaps (103).

2. The steel-concrete composite arch rib structure according to claim 1, characterized in that: The cross-sectional dimensions and arrangement of precast block A (4) and precast block B (5) are set as follows: The cross section of the arch rib steel pipe (1) is fully filled, the cross section porosity meets the bearing capacity and durability requirements of the steel pipe concrete arch rib structure and is minimized as much as possible, and the types of precast concrete blocks are simplified. The side length of the regular hexagon of the precast block (4) is determined by adapting it to the inner diameter of the arch rib steel pipe (1).

3. The steel-concrete composite arch rib structure according to claim 1, characterized in that: A first protrusion point (401) is set at the midpoint of the three adjacent sides of the precast block (4) regular hexagon. The height of the first protrusion point (401) is equal to the width of the gap (102) between the precast blocks. A second protrusion point (402) is provided at the center of one end face of the precast block (4), and the height of the second protrusion point (402) is equal to the width of the longitudinal section gap (103) of the precast block.

4. A construction method for a steel-concrete composite arch rib structure according to any one of claims 1-3, characterized in that: The method includes: S1. Complete the pouring of steel fiber concrete at the arch foot (13) of the arch bridge and the closure of the steel arch. Set up several manholes (2) on the arch rib steel pipe (1) and set up a temporary working platform (3). S2. Divide the cross section of a single steel pipe into several prefabricated units according to the cross section size of the arch rib steel pipe (1), calculate the reserved hole wall gap (101) and the inter-block gap (102), and press the prefabricated blocks in the factory. S3. Transport the precast blocks to the temporary work platform (3) next to the arch rib steel pipe (1), lower the precast blocks into the arch rib steel pipe (1) through the manhole (2) and transport them to the installation position. S4. Using an in-pipe installation robot (10), each precast block is precisely positioned along the pipe wall, staggered in the longitudinal direction, and a cross-sectional gap (103) is reserved to complete the laying and installation of all precast blocks in the steel pipe. S5. Vacuum-assisted grouting process is used for the arch rib steel pipe (1) after the precast blocks have been installed. Grout is injected into the hole wall gap (101), block gap (102), and cross-sectional gap (103) in several sections along the arch rib axis of the steel pipe to complete the grouting construction inside the steel pipe.

5. The construction method of a steel-concrete composite arch rib structure according to claim 4, characterized in that: Manholes (2) are arranged at intervals along the length of the arch rib steel pipe (1). The arrangement of manholes (2) is adapted to the grouting section position of the arch rib steel pipe (1). The diameter of manholes (2) meets the requirements for the placement of precast blocks and the operation inside the pipe. Each precast block is made of low water-cement ratio concrete and is pressed into shape in the factory, with shrinkage rate controlled during the molding process.

6. The construction method of a steel-concrete composite arch rib structure according to claim 4, characterized in that: In step S3, towers (6) are set on the sides of the arch feet (13) at both ends of the arch bridge, and the cable suspenders (7) are set above the arch bridge through the towers (6); The precast blocks are hoisted from the arch foot (13) of the arch bridge to the corresponding temporary work platform (3) on the arch bridge by cable crane (7). The auxiliary handling equipment (8) transports the precast blocks on the temporary work platform (3) through the manhole (2) to the pipe transport vehicle (9) inside the arch rib steel pipe (1). The winch (11) pulls the pipe transport vehicle (9) down to the work surface through the wire rope (12) to dock with the pipe installation robot (10).

7. The construction method of a steel-concrete composite arch rib structure according to claim 4, characterized in that: In step S4, the precast blocks are stacked vertically from bottom to top in the arch rib steel pipe (1). Precast block A (4) is placed with the three first protrusion points (401) all facing down, so that the adjacent precast blocks are supported by the first protrusion points (401) to form a uniform inter-block gap (102). The outer B precast block (5) is attached to the adjacent A precast block (4) and is stacked layer by layer synchronously with the A precast block (4). The side wall of the B precast block (5) is adapted to the outer wall of the A precast block (4) and the inner wall of the arch rib steel pipe (1).

8. The construction method of a steel-concrete composite arch rib structure according to claim 7, characterized in that: In step S4, when the precast blocks are laid vertically layer by layer along the arch rib steel pipe (1), the adjacent two layers of precast blocks are arranged in a longitudinal staggered manner, and the width of the staggered joint is adapted to the length of the precast block. The second protruding point (402) of the precast block (4) is arranged in the same direction, so that a uniform cross-sectional gap (103) is formed between the longitudinally adjacent precast blocks in the same layer.

9. The construction method of a steel-concrete composite arch rib structure according to claim 1, characterized in that: In step S5, before grouting, the gap cavity of the precast block inside the arch rib steel pipe (1) is vacuumed to create a negative pressure environment in the cavity to remove air. During the grouting process, the grout uniformly fills the gaps (101) between holes, the gaps (102) between blocks, and the gaps (103) in the cross section under the combined action of negative pressure and grouting pressure.

10. The construction method of a steel-concrete composite arch rib structure according to claim 9, characterized in that: The arch rib steel pipe (1) is divided into multiple grouting sections along its axial direction and is implemented sequentially. The division of each grouting section is adapted to the axial laying unit of the precast block and the location of the manhole (2). After a single grouting section is completed, the next grouting section is carried out. The grout in adjacent grouting sections is tightly connected to ensure the integrity of the grouting of the entire pipe section.

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