Multi-stage construction method for V-shaped bridge tower under limited space condition

Abstract

The invention relates to a multi-stage construction method for a V-shaped bridge tower under the limited space condition, and belongs to the technical field of bridge construction. The method comprises the steps that a three-dimensional coordinate method is combined with an elevation projection correction formula to conduct cable tower millimeter-level lofting; the installation deviation of the stiff skeleton is controlled to be smaller than or equal to 2 mm through a pre-embedded angle steel positioning frame and a double-total-station threading positioning technology; a construction process is dynamically selected based on spatial constraint, specifically, the first to second sections of the lower tower column are subjected to rollover construction, the third section of the transition section is subjected to rollover and creeping formwork mixed construction, and more than or equal to 4 sections of the upper tower column are synchronously jacked by hydraulic creeping formworks. Climbing cone anti-failure three-level control is innovatively provided, specifically, thread go gauge screening is conducted, embedded part spot welding fixing is conducted, and the torque of a high-strength screw is smaller than or equal to 20 N.m; the inner mold platform is integrally lifted through the bearing steel pins. The problems that under the condition that the space is limited, a formwork for bridge tower construction is difficult to install, positioning precision is insufficient, and efficiency is low are solved, and high-precision linear control, safe and efficient operation and adaptive construction of a complex structure are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge construction, and specifically relates to a construction method for a V-shaped bridge tower under space-constrained conditions, and in particular to a high-precision installation and positioning of a rigid frame and a multi-stage dynamic construction process. Background Art

[0002] As modern transportation networks extend into complex terrain, V-shaped pylons are increasingly being used in long-span cable-stayed bridges across canyons and rivers due to their excellent wind resistance and aesthetic value. These pylons typically exhibit a bidirectional tilted structure, with the pylon legs typically angled between 35° and 60°. While this improves structural rigidity, it also creates a narrow triangular area at the base of the pylon, often compressing construction space to less than 5m. 2 This limited space poses severe challenges to traditional construction techniques.

[0003] In terms of positioning control, the rigid frame serves as the installation base for the rebar and formwork, and its positioning accuracy directly affects the tower column alignment. Traditional methods rely on coordinate setting out using a single total station. However, in the construction of V-shaped towers over 120 meters, the cumulative error can easily exceed 5mm due to high-altitude wind vibration and deformation caused by temperature fluctuations due to sunlight.

[0004] The lack of adaptability of construction techniques is another key bottleneck. While hydraulic climbing formwork technology offers efficiency advantages in ultra-high bridge towers, its standard frame width requires an operating space of more than 3m, making it impossible to deploy in the initial sections where the lower tower column width is often less than 2.5m. While flip formwork construction can adapt to narrow spaces, it takes an average of 72 hours per section, and the risk of high-altitude formwork removal is extremely high. More seriously, at complex nodes such as the tower pier beam consolidation section, traditional processes struggle to balance space occupancy and structural stability, often requiring the erection of large temporary supports, significantly increasing construction costs.

[0005] Reliability issues with embedded components further exacerbate construction risks. Climbing cones, the core anchoring point for hydraulic climbing formwork, require installation accuracy of ±2mm. However, in actual construction, embedded component displacement due to vibration during concrete pouring is common, and the failure rate of high-strength screw ejector pins is also high.

[0006] Therefore, it is urgent to develop a construction method that integrates high-precision positioning and dynamic process adaptation to fundamentally break through the technical bottleneck of V-shaped bridge towers under spatial constraints. Summary of the Invention

[0007] This paper proposes a multi-stage construction method for V-shaped bridge towers under space-constrained conditions. This method aims to overcome the limitations imposed by the narrow space at the base of the V-shaped bridge tower columns on the construction environment and efficiency through a "measurement-positioning-dynamic process adaptation" technology chain. The specific solution is as follows: Multi-stage construction method for V-shaped pylons under space-constrained conditions, including: S1. Tower position measurement and positioning, using the 3D coordinate method for layout, and performing 3D coordinate measurement based on the control points of the tower's external control network; S2. Rigid frame installation and positioning, including: Pre-embed the positioning angle steel frame on the top surface of the next section of concrete; Hoist the rigid frame and place it in the positioning frame; Use dual total stations to thread lines on the vertical and horizontal axes of the tower column, and adjust the rigid frame so that the lower axis point of the cable tower is aligned with the center point of the horizontal brace on the upper part of the rigid frame; S3. Complete the pylon reinforcement binding and embedded cone installation based on the rigid skeleton; S4. Dynamically select construction technology based on spatial constraints: The 1st and 2nd sections of the lower tower column are constructed using flip formwork; The third section of the transition section is constructed using a combination of flip formwork and climbing formwork; The 4th section and above of the upper tower column are constructed using hydraulic climbing formwork.

[0008] Preferably, the specific steps of the three-dimensional coordinate method lofting in S1 include: Determine the stakeout points using a total station Relative measuring station Slope distance , Zenith distance and horizontal values ,calculate Point coordinates: Introduce elevation projection surface correction and calculate projection correction number : in, 、 、 Respectively Pointed 、 、 Direction coordinates; 、 、 Respectively represent the measuring station of 、 、 Direction coordinates; Indicates the distance on the station elevation surface. Indicates height difference, Represents the radius of curvature of the Earth.

[0009] Preferably, the rigid frame is formed by welding angle steel, the vertical reinforcement processing error is ≤2mm, and the rigid frame segment length is 6m.

[0010] Preferably, the specific operations of the dual total station threading and positioning in step S2 include: The total station is set on the axis farther away from the tower in the transverse direction of the bridge and on the ground or approach bridge in the longitudinal direction of the bridge; The lower part of the skeleton is positioned by coordinates, and the upper part is fine-tuned by threading the longitudinal and transverse axes.

[0011] Preferably, the steel bar binding in step S3 specifically includes: Install the steel bar positioning ring on the rigid frame, and the positioning ring is determined by measurement and setting out; The main reinforcement is connected with straight threaded sleeves, the stirrups are overlapped and tied, and protective layer pads are arranged between the steel bar layers.

[0012] Preferably, the embedded part climbing cone installation includes: Before embedding, check the integrity of the climbing cone thread and use steel bar spot welding to connect the embedded steel plate and the pier body steel bar; The red area at the end of the high-strength screw needs to be fully screwed into the climbing cone. The installation torque .

[0013] Preferably, the mold remodeling construction includes: When assembling the template, the distance between the bottom horizontal back rib and the bottom of the template ; When pouring concrete, stick double-sided tape on the top of the formwork, covering 100mm below; The back ribs at the chamfered corners are welded with inclined brackets and tightened with high-strength screws.

[0014] Preferably, the hydraulic climbing formwork construction includes: After the concrete strength reaches 10MPa, the formwork is removed and the formwork is moved back 0.6m; Install embedded parts bracket, hydraulic system lifting speed ; After climbing into place, the embedded parts are locked through the anchoring device.

[0015] Preferably, for the construction of the tower pier beam consolidation section: Remove the inner climbing formwork and use the corbel and truss construction support; The inner side of the 1st and 2nd sections of the lower tower column adopts flip formwork, and the inner side climbing formwork of the 3rd section is installed to be converted into a full climbing formwork.

[0016] Preferably, the method further includes the step of lifting the inner mold operating platform: Concrete strength Then remove the inner mold; Install the hanging bracket to the embedded parts of the previous section; Lift the steel platform and insert the load-bearing steel pins, and then remove the embedded parts system of the previous section before lifting the platform.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention fundamentally solves the construction problem of V-shaped bridge towers under space-constrained conditions through the collaborative innovation of the dual-axis precise positioning of the rigid skeleton and the multi-level dynamic construction process. In terms of positioning accuracy, the dual total station threading positioning mechanism achieves millimeter-level error control. The traditional single-instrument coordinate layout is affected by the swing of the tower column, and the cumulative error at a height of 120m can reach more than 5mm, resulting in a low qualified rate of the steel bar protective layer. The present invention forms a dual constraint of "optical calibration + mechanical limit" by synchronously emitting lasers on the longitudinal and transverse axes, combined with the physical positioning angle steel frame embedded in the top surface of the concrete, which completely eliminates the risk of concrete protective layer falling off due to positioning deviation.

[0018] 2. Breakthrough in spatial adaptability is the core value of this invention. The operating space of the lower column of the V-shaped tower is less than 3m. 2 In order to solve the pain points of the project, we creatively adopted the three-level dynamic switching strategy of "flip formwork-climbing formwork-full climbing formwork": flip formwork is preferred for sections 1-2 of the lower tower column. The horizontal back ribs at the bottom of the formwork are close to the concrete surface and the 100mm sealing measure is taken below, so that efficient formwork can be achieved in a narrow space; the third section of the transition section adopts a mixed process, the narrow inner cavity continues to be flipped, and the climbing formwork frame is installed on the outside simultaneously; more than 4 sections of the upper tower column are converted to full climbing formwork construction, and the hydraulic system is synchronously lifted at a speed of ≤300mm / min, which significantly improves the construction efficiency in narrow areas where traditional climbing formwork cannot be deployed.

[0019] 3. This invention pioneers a three-level protection system: thread screening, spot welding, and torque control. Pre-embedding inspection uses a gauge to eliminate thread defects and tapering. The embedded steel plate and pier reinforcement are spot welded at 200mm intervals, reducing displacement to zero after vibratory pouring. The high-strength screw installation torque is limited to ≤20N·m, eliminating accidents involving ejection of the elastic cylindrical pin. A concurrently implemented closed internal mold platform lifting process, through the mechanical interlocking of the load-bearing steel pin and the bracket, allows workers to remove embedded parts without the need for high-altitude scaffolding, significantly reducing safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0021] Figure 1 This is a schematic diagram of positioning and installation of the rigid frame of the present invention; Figure 2 This is a schematic diagram of fixing the embedded climbing cone of the present invention; Figure 3 This is a schematic diagram of the template structure of the present invention; Figure 4 Schematic diagram of the inner mold platform structure of the present invention; Figure 5 This is a schematic diagram of the inner and outer molds of the present invention; Figure 6 This is a flow chart of the steps for lifting the inner mold operating platform of the present invention; Figure 7 This is a flow chart of the multi-stage construction of the bridge tower of the present invention; Figure 8 This is a schematic diagram of the three-dimensional coordinate measurement method of the present invention; Figure 9 This is a schematic diagram of the elevation projection correction of the present invention; Figure 10 It is a schematic diagram of the climbing process of the hydraulic climbing formwork system of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0023] Example 1: This embodiment provides a multi-stage construction method for a V-shaped bridge tower under space-constrained conditions. The construction method is described in detail with reference to a V-shaped cable tower project example of a cross-river bridge. The total height of the cable tower is 158m, the inclination angle of the lower tower column is 52°, and the operating space at the base of the tower leg is only 2.8m×3.2m, which is a typical space-constrained working condition. The space-constrained working condition refers to the projected area of ​​the operating area at the base of the tower leg being less than 9m 2 .

[0024] like Figure 7 As shown, based on the cross-sectional shape of the tower column, sections 1-2 of the lower tower column were constructed using flip formwork. Climbing formwork began construction on section 3 of the lower tower column. Due to the constraints of the lower crossbeam, the middle portion of the third section continued to be constructed using flip formwork, while section 4 was converted to full climbing formwork. When construction reached the tower pier beam consolidation section, the inner and large and small mileage climbing formwork were removed, and brackets and trusses were used to construct the tower pier beam consolidation section support. The outer tower column continued to be constructed using climbing formwork. Due to the spatial limitations of the beam, sections 1-2 of the upper tower column were constructed using flip formwork on the inner side, and climbing formwork on the outer side. Starting from section 3, climbing formwork was installed on the inner and large and small mileage directions, and construction continued using climbing formwork until the tower top.

[0025] Specifically, the first step: Figure 1As shown, a high-precision measurement control network was established. Six reinforced concrete observation piers were deployed within 200 meters of the tower, with forced centering bases installed on top. A three-dimensional coordinate system of control points was established through GPS static measurement combined with precision leveling. This established a millimeter-level benchmark for the installation of the rigid frame.

[0026] Step Two: Preparation and Installation of the First Section of the Pier Shaft Rigid Frame. The ribs are fabricated in sections at the processing yard, where positioning frames are welded from steel sections to prevent deformation during welding. The ribs consist of a steel truss formed from welded angle steel, with each section measuring 6 meters. Before installing the first section, positioning angle steel, according to the rib dimensions, is embedded in the concrete of the section below to ensure accurate positioning and elevation. After hoisting, the ribs are placed directly into the positioning frames. Once the ribs are positioned, the dual total station threading and fine-tuning system is activated: a transverse total station is set up at an axis point 50 meters from the tower center to measure the coordinates of the lower corners of the ribs and adjust them to the design values ​​using jacks; a longitudinal total station is located 80 meters outside the approach bridge. A reflector is attached to the center of the cross brace on the ribs, and a laser beam is emitted. The dual beams formed a cross-reference plane in space, and the rigid frame was fine-tuned to align the laser intersection with the center of the cross brace. This dual constraint system of optical alignment and mechanical limiting, using a "dual total station threading + embedded angle steel frame," addressed the bidirectional offset coupling problem unique to V-shaped towers, minimizing offset. After positioning, CO2 gas shielded welding was performed in sections, with the interpass temperature controlled at ≤120°C. Deformation was monitored in real time during the welding process.

[0027] Step 3: Installation of cable tower reinforcement and embedded climbing cone. Before installing the reinforcement, first install the reinforcement positioning ring on the rigid frame. The positioning ring is installed by measuring and accurately laying out to ensure accurate installation of the reinforcement. Before installing the formwork, arrange a sufficient number of reinforcement protective layer pads on the inner and outer layers of reinforcement to ensure the thickness of the reinforcement protective layer. Optionally, the reinforcement protective layer pads are 40×40×30mm high-strength mortar prefabricated parts. The reinforcement installation is carried out in the order of installing the vertical main reinforcement first and then installing the horizontal stirrups. The main reinforcement is connected with a straight threaded sleeve, and the stirrups are overlapped and tied. The reinforcement is processed and formed in the processing plant and transported to the construction site. The reinforcement installers operate using an automatic climbing platform.

[0028] Because the climbing cone is pre-embedded, in order to prevent the vibrating rod from touching the embedded parts and causing them to move out of position during concrete pouring, the embedded parts steel plate and the pier body steel bars are connected by spot welding. Before pre-embedding the climbing cone, a three-level quality control is implemented: first, the thread integrity is checked with an M36 go / no-go gauge; then, Rebar is spot-welded to connect the embedded steel plate and the main pier reinforcement at 200mm intervals, with a weld leg height of 4mm. When installing the high-strength screws, ensure that the red-painted 50mm area at the end is fully screwed into the cone, using a torque wrench limit of 18N·m. This measure ensures zero displacement of the embedded parts and ≤0.1mm compression of the elastic cylindrical pin. If any high-strength screws are found to be damaged before embedding, they must be discontinued and replaced promptly.

[0029] When installing the high-strength screw and climbing cone, do not use excessive force, as this will cause the high-strength screw to push the elastic cylindrical pin in the center of the climbing cone out to the position where the force bolt is installed, making it impossible to install the force bolt. To ensure the connection length between the high-strength screw, climbing cone and embedded plate, the red area at the end of the high-strength screw must be screwed into the climbing cone and embedded plate.

[0030] Step 4: Set up the inner formwork operation platform. The inner box of the main tower is relatively small. In order to provide a working surface for formwork and other operations, a special inner formwork platform structure is designed for inner formwork construction. The inner formwork construction platform is mainly composed of anchor assembly, hanging bracket, load-bearing beam, platform panel system and drop platform. Each load-bearing unit is supported on two special hanging brackets symmetrically set along the bridge direction. The brackets transfer all construction loads on the platform to the anchor assembly. Figure 2 As shown, the anchor assembly consists of a climbing cone, load-bearing bolts, a disposable, non-returnable embedded plate, and high-strength screws, consistent with the climbing formwork system. The upper portion of the hanging bracket is angled and open, facilitating accurate positioning of the platform beam and bracket. Wooden planks and a gangplank are placed on the load-bearing unit to form a working platform. A retractable manhole cover is located on the top of the platform, allowing construction workers to descend to the suspended platform for work such as removing and repairing the climbing cone.

[0031] like Figure 4 As shown, the erection of the inner formwork platform mainly includes the following steps: using steel sections to make the inner formwork integral steel platform skeleton; pre-embedding the embedded parts system when pouring the tower wall concrete; using a tower crane to hoist the steel platform on the embedded parts and insert the load-bearing pins; installing the hoisting platform steel skeleton and laying the hoisting platform panel working surface; laying the steel platform panel to form the inner formwork working platform; using a tower crane to hoist the inner formwork for subsequent construction.

[0032] Step 5: Manufacturing and installation of internal and external formwork. The external formwork of the single-leg pier body is equipped with 21mm thick imported Visa board, 6 chamfers are made of 6 pieces of fixed steel formwork, and the internal formwork is made of 15mm bamboo plywood. The template panel is 6.15m high, the vertical back ribs are H200 wood I-beams (section size 80x200), the beam height is 6m, the horizontal spacing does not exceed 0.3m, the horizontal back ribs are 14# channel steel, and the vertical spacing does not exceed 1.35m. In order to prevent the joints between the upper and lower segments from misalignment and leakage, when assembling the template, the bottom horizontal back rib shall not be more than 35cm away from the bottom of the template, and a circle of double-sided tape shall be affixed to the upper mouth when pouring concrete, and 100mm shall be wrapped under each standard pouring layer to make the template close to the poured concrete surface. Figure 3 and Figure 5 As shown, the imported Visa panels are connected to the vertical ribs of the I-beam with self-tapping screws. The vertical ribs are connected to the horizontal ribs of the double-slot steel backing with connecting claws. Two hooks are symmetrically located on either side of the vertical ribs. The two formwork panels are connected with a core strap and fixed with a core strap pin, ensuring the integrity of the formwork and making the stress on the formwork more reasonable and reliable.

[0033] Step 6: First, join the inner and outer forms. To achieve a smooth, glossy, and sharply defined exterior concrete surface for the pier, the connection between the formwork is crucial. To ensure the quality of formwork assembly, two key aspects are controlled: first, the connection between the panels is crucial for ensuring smooth joints and minimal misalignment between the individual formwork groups; second, the quality of the connection between the transverse ribs enhances the overall formwork rigidity and ensures the overall smoothness of the pier's external dimensions. The formwork utilizes four ribs, ensuring overall rigidity. Formwork on different sides is connected by a core strip with a pin inserted between the two sides. To prevent mold expansion, the ribs at the chamfers are reinforced with diagonal braces tightened with high-strength screws. Non-vertical chamfers require on-site welding of ribs to the ribs. The four corners of the pier are connected to the wooden formwork using steel angle forms with hook bolts. The four corners are tightened using a diagonal bracing system.

[0034] Step 7: Concrete pouring and curing of the first section. C55 concrete is used for the lower tower column from 5m away from the bottom of the beam to 10m above the bridge deck of the upper tower column, and C50 concrete is used for the rest of the upper tower column. Cement, sand, and stone used for concrete should avoid materials that may cause alkali-aggregate reaction. Before pouring concrete, the concrete surface should be sprinkled with water to moisten it, but no water should accumulate. Concrete is poured in layers using a ground pump, with a layer thickness of 30cm, and gradually advancing in a horizontal direction. When spreading concrete, the height of the concrete pouring should not exceed 2m. If it exceeds 2m, a string tube is used for spreading. The concrete inside and outside the tower column is cured using a follow-up spray curing method.

[0035] Step 8: Fabrication and installation of the second section of the pier body rigid frame, installation of the cable tower reinforcement, and installation of the embedded climbing cone.

[0036] Step 9: The first section of the formwork is removed and the inner mold operating platform is lifted. The lifting of the inner mold operating platform is mainly completed by the cooperation of the tower crane or the chain hoist. The lifting steps are as follows: Figure 6 As shown in the figure, due to the limited space inside the tower column box, a tower crane is required to remove the inner formwork each time the inner formwork platform is lifted. When the concrete strength reaches 15 MPa or above, all tie rods, including the external angle braces, are removed, the inner formwork is withdrawn, and the formwork is lifted off the tower crane to the designated site. The brackets are then installed on the embedded parts of the next section.

[0037] Step 10: Install the outer climbing formwork bearing frame of the pier body and the formwork on the frame. Set up the inner formwork steel pipe support and install the inner formwork. Use a tower crane to lift the inner formwork steel platform, extract the bearing pins, and hoist the inner formwork steel platform to the embedded parts of the next section. Insert the bearing pins, remove the embedded parts system of the previous section on the lifting platform, and modify the embedded holes.

[0038] Step 11: The second section is to close the inner and outer molds, pour concrete and maintain.

[0039] Step 12: Fabrication and installation of the third section of the pier body rigid frame, installation of the cable tower reinforcement, and installation of the embedded climbing cone.

[0040] Step 13: Remove the inner formwork, install the inner climbing formwork load-bearing frame, and install the inner formwork on the frame. Raise the outer climbing formwork and install the hoisting platform. When the concrete strength reaches 6MPa, loosen the tie rods one or two times. When the concrete strength reaches 10MPa, remove the formwork and climb. During the climb, remove the tie rods, move the formwork back 0.6m, install the embedded component hangers, and then raise the guide rails. Then, remove the formwork and remove the lower embedded component hangers to prepare for the next turnover.

[0041] Step 14: The third section: close the inner and outer formwork, pour concrete, and maintain. After climbing into position, close the formwork, connect the tie rods, measure the formwork, complete the acceptance, pour concrete, and when the concrete reaches the required strength, remove the formwork and start the next cycle.

[0042] Step 15: The hydraulic climbing formwork climbs up and casts the pier body and segments in turn.

[0043] Step 14: The third section: close the inner and outer formwork, pour concrete, and maintain. After climbing into position, close the formwork, connect the tie rods, measure the formwork, complete the acceptance, pour concrete, and when the concrete reaches the required strength, remove the formwork and start the next cycle.

[0044] Step 15: The hydraulic climbing formwork climbs up and casts the pier body and segments in turn.

[0045] Quality verification data showed: the maximum deviation in rigid frame positioning was 1.8mm; the qualified rate of the steel bar cover was 98.2%; the pre-embedded deviation of the climbing cone was ≤2.1mm; and the peak-to-peak error in the hydraulic climbing synchronization was 3.2mm. The entire tower construction period was shortened by 28% compared to traditional methods, saving over 2 million yuan in temporary support costs.

[0046] Example 2 The position of the cable tower in the first embodiment is laid out by a three-dimensional coordinate method, and the three-dimensional coordinate measurement and positioning of the cable tower is performed by an external control method based on the control points of the dedicated control network outside the cable tower.

[0047] Specifically, if Figure 8 As shown, when using Leica TS60 total station to stake out the tower axis, the instrument is set up at the measuring station. Its coordinates are ( ), without considering the control points Under the premise of coordinate error, The point coordinates are (0,0,0). The prism is placed at the design position. , and the slope distance is obtained from the actual measurement , Zenith distance and horizontal values Then, the relative coordinates are calculated by the spatial coordinate conversion formula : in, 、 、 Respectively Pointed 、 、 Direction coordinates.

[0048] According to the measurement error theory, when the error of the starting point is not considered, 、 The error calculation formula is: If the elevation error of the starting point is not considered and the refraction error is not taken into account, the elevation The error calculation formula is: Where, 、 、 Respectively represent the stakeout points Relative measuring station of 、 、 Errors in directional coordinates; 、 、 Respectively represent the stakeout points Relative measuring station Slope distance , horizontal direction value , Zenith distance error.

[0049] 、 、 , slope distance , horizontal direction value and zenith distance According to the actual situation of the construction site, the accuracy of the instrument used, and the number of observations, the position coordinates of the cable tower can be obtained by substituting them into the above formula ( ) and its accuracy ( , , ).

[0050] against Point and Height difference of points To avoid the influence of the earth curvature, the elevation projection surface is corrected. Figure 9 As shown, For the measuring station, is the tower axis, The distance from the axis point to the measuring station on the measuring station elevation surface, and its projection correction number is for: From this we can calculate the slope distance during layout Distance from zenith The correction numbers are 、 : After correction, the final layout error is controlled within 0.8mm, laying a millimeter-level benchmark for the installation of the rigid frame.

[0051] Example 3: like Figure 10 As shown, the climbing method of the hydraulic climbing formwork system in Example 1 is as follows: Step 1: Pre-embed climbing cones or bolts in the concrete structure to serve as anchor points for the climbing formwork. Then, assemble the climbing formwork system, including the formwork system, climbing frame, hydraulic system, and anchoring devices, at the ground or starting level, and calibrate its verticality. After tying the reinforcement for the current layer, pour concrete into the formwork and properly cure it until it reaches the design strength. When the concrete strength reaches 6MPa, loosen the tension screws one or two times. When the concrete strength reaches 10MPa, remove the formwork and proceed with climbing.

[0052] Step 2: Start the hydraulic system, the hydraulic cylinder contracts, separates the formwork from the concrete surface, removes the tension screws, moves the formwork back 0.6m, and completes the demoulding operation.

[0053] Step 3: Install the embedded parts bracket.

[0054] Step 4: The hydraulic system continues to push the entire formwork system and climbs up one construction floor height along the guide rail. During the climbing process, the guide rail and the climbing formwork frame achieve stable climbing of the frame by alternately attaching to the wall and lifting each other. The formwork is then withdrawn and the lower embedded parts bracket is removed in preparation for the next turnover.

[0055] Step 5: After climbing into place, the anchoring device is locked on the embedded parts in the new position, the mold is closed, the tension screws are connected, and the template is measured.

[0056] Step 6: Complete the acceptance of pouring concrete, wait until the concrete reaches the required strength, remove the formwork and start the next cycle.

[0057] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A multi-stage construction method for V-shaped bridge towers under space-constrained conditions, characterized in that: include: S1. Tower position measurement and positioning, using the 3D coordinate method for layout, and 3D coordinate measurement based on the control points of the tower's external control network; S2. Rigid frame installation and positioning, including: Pre-embed the positioning angle steel frame on the top surface of the next section of concrete; Hoist the rigid frame and place it in the positioning frame; Use dual total stations to thread lines on the vertical and horizontal axes of the tower column, and adjust the rigid frame so that the lower axis point of the cable tower is aligned with the center point of the horizontal brace on the upper part of the rigid frame; S3. Complete the pylon reinforcement binding and embedded cone installation based on the rigid skeleton; S4. Dynamically select construction techniques based on spatial constraints: The 1st and 2nd sections of the lower tower column are constructed using flip formwork; The third section of the transition section is constructed using a combination of flip formwork and climbing formwork; The 4th section and above of the upper tower column are constructed using hydraulic climbing formwork.

2. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The specific steps of the three-dimensional coordinate method lofting in S1 include: Determine the stakeout points using a total station Relative measuring station Slope distance , Zenith distance and horizontal values ,calculate Point coordinates: Introduce elevation projection surface correction and calculate projection correction number : in, 、 、 Respectively Pointed 、 、 Direction coordinates; 、 、 Respectively represent the measuring station of 、 、 Direction coordinates; Indicates the distance on the station elevation surface. Indicates height difference, Represents the radius of curvature of the earth, which is 6371 km.

3. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The rigid frame is formed by welding angle steel, the vertical reinforcement processing error is ≤2mm, and the rigid frame segment length is 6m.

4. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The specific operations of the dual total station threading and positioning in step S2 include: The total station is set on the axis farther away from the tower in the transverse direction of the bridge and on the ground or approach bridge in the longitudinal direction of the bridge; The lower part of the rigid frame is positioned by coordinates, and the upper part is fine-tuned by threading the longitudinal and transverse axes.

5. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The steel bar binding in step S3 specifically includes: Install the steel bar positioning ring on the rigid frame, and the positioning ring is determined by measurement and setting out; The main reinforcement is connected with straight threaded sleeves, the stirrups are overlapped and tied, and protective layer pads are arranged between the steel bar layers.

6. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The embedded component climbing cone installation in step S3 includes: Before embedding, check the integrity of the climbing cone thread and use steel bar spot welding to connect the embedded steel plate and the pier body steel bar; The red area at the end of the high-strength screw needs to be fully screwed into the climbing cone. The installation torque .

7. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: In step S4, the mold remodeling construction includes: When assembling the template, the distance between the bottom horizontal back rib and the bottom of the template ; When pouring concrete, stick double-sided tape on the top of the formwork, covering 100mm below; The back ribs at the chamfered corners are welded with inclined brackets and tightened with high-strength screws.

8. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1 is characterized in that: The hydraulic climbing formwork construction includes: After the concrete strength reaches 10MPa, the formwork is removed and the formwork is moved back 0.6m; Install embedded parts bracket, hydraulic system lifting speed ; After climbing into place, the embedded parts are locked through the anchoring device.

9. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1, characterized in that: Regarding the construction of the tower pier beam consolidation section: Remove the inner climbing formwork and use the corbel and truss construction support; The inner side of the 1st and 2nd sections of the lower tower column adopts flip formwork, and the inner side climbing formwork of the 3rd section is installed to be converted into a full climbing formwork.

10. The multi-stage construction method for V-shaped bridge towers under space-constrained conditions according to claim 1, characterized in that: It also includes the steps for lifting the inner mold operating platform: Concrete strength Then remove the inner mold; Install the hanging bracket to the embedded parts of the previous section; After hoisting the steel platform, the embedded system of the previous section is removed.

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