Construction method for variable cross-section formwork with section adjustment

Abstract

The application relates to the field of bridge pier construction and discloses a variable cross-section formwork collecting and adjusting construction method, which comprises a climbing part sleeved on a climbing rod, a whole truss rigidly connected through the climbing part, an operation platform and a maintenance platform respectively arranged above and below the whole truss, and a turnover channel arranged between the operation platform and the maintenance platform; a formwork is arranged between the truss and the surface of a pier; a roller shaft is arranged on the surface of the whole truss and used for abutting against the formwork and rolling along with the climbing of the whole truss; the whole truss comprises an inner formwork surrounding ring and an outer formwork surrounding ring located in the inner ring and the outer ring of the pier; the inner formwork surrounding ring comprises a left truss and a right truss; an abutting frame is connected between the left truss and the right truss; a pressure bearing limiting rod is arranged between the abutting frame and the left and right trusses; the pressure bearing limiting rod is rotationally arranged on the abutting frame; the rotation of the pressure bearing limiting rod is linked with the movement of the left and right trusses; and the pressure bearing limiting rod is used for sharing the pressure of the left and right trusses on both sides of the formwork to the middle, so as to prevent the formwork from being broken and deformed.

Description

Technical Field

[0001] This invention relates to the field of bridge pier construction, specifically to a construction method for adjusting the tapering of variable cross-section formwork. Background Technology

[0002] The bridge piers are hollow, with pre-embedded climbing rods. Each pier consists of a long side and a short side. The long side slopes upwards to create a tapering effect, while the short side is straight. Both sides have pre-embedded climbing rods. The climbing rods embedded in the long side have the same slope as the long side, while the climbing rods embedded in the short side are vertical and straight. These climbing rods allow the work platform to ascend. Currently, during the construction of high bridge piers, the sliding formwork is prone to scraping and pulling on the not-yet-fully-hardened concrete during the sliding process, causing significant damage to the surface of the formed pier concrete. This can lead to surface defects such as pitting and cracking, affecting the overall quality of the pier's formation. Summary of the Invention

[0003] The present invention aims to provide a construction method for adjusting the tapering of variable cross-section formwork to solve the problems of surface damage, pitting, and cracking caused by scraping of concrete.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a construction method for adjusting the tapering of a variable cross-section formwork, comprising the following steps: S1: Before pouring the concrete for the pier cap, measure and lay out the four corners of the pier column. Based on the positions of the four corners, locate the pre-embedded positions of the climbing rods. The pre-embedded positions are determined according to the positions of the pier column reinforcement bars and do not affect the installation of the main reinforcement bars and the sliding of the jacks. According to the layout, the bolts are pre-embedded into the pier cap of the pier column. The base pipe and pressure plate are installed on the pier cap and fixed with bolts. Finally, the climbing rod is installed in the base pipe and fixed. S2: The main reinforcement bars of the pier column can be made in lengths of 4.5m or 6m. After the first formwork of main reinforcement bars is installed, the stirrups are installed at a height of 1.3m. S3: Determine the positioning lines for the overall truss installation on the pier and mark them; S4: Before installing the overall truss, pass the jacks and self-locking devices through the pre-embedded climbing rods to ensure consistent height and lock them in place; install the overall truss using a crane, reserving space for the template during installation, installing supports on the overall truss, and fixing the jacks and self-locking devices to the supports; finally, install the operating platform, safety railings, steel bar racks, hydraulic system operating console, and other auxiliary equipment. S5: The template is pre-applied with release agent and installed between the overall truss and the reinforcing steel. The four corners of the pier are connected to the template slots using rounded corner devices to ensure the integrity of the pier corners. S6: The first pour of concrete is 0.9m long, which serves as support for the entire formwork system. 0.1m is reserved for the installation of the second-level formwork. The pouring should be carried out in layers, with each layer being 30 to 45 centimeters. After the concrete is poured, the surface should be roughened and the measurement should be repeated to confirm that the position of the pier column is correct. S7: After the concrete pouring is completed, the second layer of pouring segment steel reinforcement is installed during the period when the concrete strength has not reached the overall truss lifting requirements. The installation height of the stirrups will not affect the position of the jacks. S8: 12 hours after the concrete is poured, the entire truss is lifted by jacks. The first lifting stroke is 70 cm. During the lifting process, observe whether the formwork is loose or slipping. If any is found, the lifting should be stopped immediately, then the formwork should be manually leveled and the cause of slippage should be analyzed. The lifting can only continue after the cause of slippage is resolved. After the lifting is completed, the formwork should be inspected and leveled again to ensure the installation accuracy. S9: After the first lift, the second layer of formwork is installed. The second layer and the first layer of formwork are sealed with an expansion agent to prevent grout leakage during concrete pouring. Then, concrete is poured and the outer formwork is lifted. This cycle of lifting is repeated until the 7th concrete pouring. S10: After the 7th concrete pouring is completed, the curing platform will be installed for subsequent formwork lifting. At the same time, safety ladders, lifting channels, material hoists and other facilities will be installed. After the installation is completed, the overall truss assembly will be completed and the normal continuous construction state will begin. S11: Depending on the formwork height, pour 0.7-0.9 meters each time, and carry out continuous 24-hour cycle construction. During the construction process, perform concrete curing work in accordance with the specifications.

[0005] The beneficial effects of this plan are: Preferably, as an improvement, the self-locking device is installed on the bracket, and the self-locking device includes hydraulic locks respectively disposed at the upper and lower ends of the jack.

[0006] The beneficial effects are as follows: The self-locking device relies on two sets of hydraulic locks arranged at the upper and lower ends of the jack to form an interlocking mechanism. During the climbing operation of the roller formwork device, at least one end of the jack can be continuously locked, which can resist the risk of misoperation. Even if the operator makes an operational error, the entire roller formwork device will not fall and slide down to hit the concrete surface, eliminating the hidden danger of high-altitude instability and falling, significantly improving the safety and reliability of high pier formwork climbing operation, and ensuring the personal safety of on-site construction personnel.

[0007] Preferably, as an improvement, the integral truss includes an inner membrane truss ring embedded inside the pier and an outer membrane truss ring sleeved on the outside of the pier. The integral truss is provided with rollers facing the surface of the pier, and the rollers are used to push the template against the pier body to be poured.

[0008] Preferably, as an improvement, the inner membrane truss ring includes a left truss and a right truss symmetrically arranged on both sides of the long side, and an abutment frame connecting the short sides of the left and right trusses. The outer side of the abutment frame is flush with both ends of the short sides of the left and right trusses, and is also provided with rollers. The rollers of the abutment frame are used to abut against the template between the left and right trusses on the short side of the inner ring of the pier.

[0009] Preferably, as an improvement, the left and right trusses are symmetrically and horizontally slidably connected to both sides of the abutment frame. The abutment frame is symmetrically and rotatably equipped with pressure-bearing limit rods on both sides. The angle opening between the pressure-bearing limit rods and the abutment frame is away from the pier column. Both left and right trusses are vertically fixed with component rods. The component rods are slidably sleeved on the pressure-bearing limit rods. An elastic element is provided between the pressure-bearing limit rods and the abutment frame. The elastic element is used to make the pressure-bearing limit rods unfold to both sides and drive the component rods on both sides to slide in opposite directions. When the component rods on both sides slide in opposite directions, they drive the pressure-bearing limit rods on both sides to rotate in opposite directions.

[0010] The beneficial effects are as follows: Because the long sides of the high pier have slopes, the spacing between the left and right trusses decreases during the ascent. However, since the short sides of the high pier are vertical and have no slope, the ends of the short sides of the left and right trusses are always pressed against the formwork via rollers. Therefore, in the existing technology, the formwork located on the short side of the inner ring of the pier is subjected to pressure from the left and right trusses on both sides, but not in the middle. However, it is subjected to pressure from the cement and the outer membrane truss ring in the opposite direction, making it very easy for the formwork to break or deform. Another existing technology connects the left and right trusses... There is a pressing component, but because the distance between the left and right trusses changes with the height, it is necessary to manually adjust the distance between the pressing component and the left and right trusses on both sides to adapt to the width change, which is time-consuming and labor-intensive. In this solution, force-shaping rods and pressure-bearing limit rods are used to link the horizontal movement of the left and right trusses with the rotation of the pressure-bearing limit rods. When the whole truss is located at the bottom of the pier, the elastic element unfolds the pressure-bearing limit rods on both sides. The pressure-bearing limit rods rotate and unfold to both sides, which at the same time drives the force-shaping rods on both sides to move in opposite directions, thereby driving the left and right trusses to move in opposite directions.

[0011] Since the length of the left and right trusses remains constant along their long sides, the pressure between their ends and the inner surface of the short side of the pier column is always present. Compared with existing technologies, when the overall truss is at the bottom, the pressure-bearing limit rod is in the deployed state. The component of the pressure perpendicular to the formwork is maximized and transmitted to the abutment frame. That is, the pressure on both sides of the formwork is distributed to the middle to the maximum extent, reducing the stress concentration on both sides of the formwork. At the same time, it can resist the squeezing force of the outer membrane truss ring and cement on the middle part of the formwork, thus ensuring that the formwork on the short side does not crack or deform. In addition, when the overall truss climbs from the bottom to the top, the climbing rod will first drive the two sides The left and right trusses move closer to the center, and the long sides on both sides also exert pressure on the left and right trusses, thus reducing the distance between the left and right trusses. The left and right trusses automatically slide towards each other, and the elastic components can ensure the adaptive sliding of the left and right trusses. As it climbs, the pressure-bearing limit rods rotate towards each other, and the angle between the pressure-bearing rods and the abutment frame gradually decreases, thus gradually reducing the vertical component force of the left and right trusses on the formwork. When the distance between the left and right trusses decreases, the pressure they exert on the sides of the formwork and the pressure span on the middle part decreases. Therefore, the reduction of the component force can adapt to this state and prevent the risk of reverse deformation and breakage of the formwork at high altitudes.

[0012] In addition, the elastic element ensures that the pressure-bearing limit rod always exerts an outward pushing force on the left and right trusses. Since the truss as a whole is large and the climbing rod is inclined, the horizontal component of its own gravity acts on the climbing rod. This design can balance part of the horizontal component force, reduce the pressure on the climbing rod, thereby reducing the climbing pressure of the climbing component and the friction of the climbing rod, improving the service life of the climbing component and reducing the wear of the climbing rod.

[0013] Preferably, as an improvement, the abutment frame is provided with a limiting plate, the limiting plate intersects with the rotation trajectory of the pressure limiting rod, and when the pressure limiting rod abuts with the limiting plate, the angle between the pressure limiting rod and the abutment frame is less than 180°.

[0014] The beneficial effect is that when the overall truss is located at the lowest end of the pier, the pressure limiting rod is at its maximum unfolding angle under the action of the elastic element, and the angle is less than 180 degrees. This ensures that as the truss rises, the left and right trusses can rotate smoothly towards each other under the action of the compressive force and the horizontal pressure of the climbing rod, without jamming.

[0015] Preferably, as an improvement, the abutment frame includes a base, a pressure seat fixed to the base, a pressure limiting rod rotatably connected to both sides of the pressure seat, and an elastic element set as a torsion spring, which is connected between the pressure seat and the pressure limiting rod.

[0016] Preferably, as an improvement, the outer membrane truss enclosure includes long trusses located on both sides of the long side of the pier and short trusses located on both sides of the short side of the pier. The short trusses span between the two long trusses and are slidably connected to the long trusses. The long trusses are guided by climbing rods on the long side, and the short trusses are guided by climbing rods on the short side.

[0017] The beneficial effects are as follows: the long side truss and the short side truss are slidably connected. As the outer membrane truss ring climbs upward, the cross-section of the pier gradually decreases. The short side remains unchanged, while the long side gradually contracts inward. Since the long truss is guided to climb by the climbing rods on the long side, and the short truss is guided to climb by the climbing rods on the short side, the short truss maintains vertical sliding, while the long truss is squeezed inward under the drive of the climbing rods on the long side. That is, as it climbs, the long trusses on both sides slide towards each other on the short truss, thereby achieving the purpose of adaptive contraction. Existing technologies adapt to the changing cross-section of the pier by adjusting layer by layer during climbing. Compared with existing technologies, this solution can reduce the workload and instead focus the work on formwork laying and steel reinforcement construction.

[0018] Preferably, as an improvement, a control cylinder is provided between the long truss and the short truss, the cylinder body of the control cylinder is fixed to the short truss, and the piston rod of the fixed cylinder is fixedly connected to the long truss.

[0019] The beneficial effects are as follows: Although the automatic retraction of the outer membrane truss ring can be achieved through the sliding cooperation between the slope of the climbing rod and the long and short trusses, in the actual operation of the climbing process, the mechanical drive of the inclined plane mechanism alone results in poor control accuracy of the retraction displacement. The frictional resistance and corrosion of the climbing rod will also have an impact, causing the retraction to be stuck, overshoot, or not in place. The control cylinder can actively adjust the retraction stroke to counteract the movement deviation caused by the friction of the inclined plane, and accurately control the retraction of the outer membrane truss ring, thereby ensuring that the cross-sectional dimensions of the pier body meet the design requirements.

[0020] Preferably, as an improvement, the long truss has symmetrical sliding grooves at both ends for the short truss to pass through. The sliding grooves are equipped with fixed rails for ball bearing slides, and the short truss is equipped with a sliding rail. The long truss and the short truss are slidably connected by the ball bearing slides. Attached Figure Description

[0021] Figure 1 This is a top view of the adaptive collection equipment placed on the pier in an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure along the AA direction; Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure along the BB direction; Figure 4 for Figure 1 Schematic diagram of the cross-sectional structure along the CC direction; Figure 5 These are schematic diagrams of the front and side views of the long truss structure according to an embodiment of the present invention; Figure 6 These are schematic diagrams of the front and side views of the short truss structure according to an embodiment of the present invention; Figure 7 These are schematic diagrams of the front, side, and top views of the support structure according to an embodiment of the present invention; Figure 8 This is a front view schematic diagram of the assembly of the abutment frame and the inner membrane truss ring according to an embodiment of the present invention; Figure 9 This is a side view of the assembly of the abutment frame and the inner membrane truss ring according to an embodiment of the present invention; Figure 10 This is a top view schematic diagram of the assembly of the abutment frame and the inner membrane truss ring according to an embodiment of the present invention; Figure 11 for Figure 8 Schematic diagram of the cross-sectional structure along the DD direction. Detailed Implementation

[0022] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: pier 1, climbing rod 11, integral truss 2, outer membrane truss ring 21, long truss 211, sliding groove 2111, fixed rail 2112, short truss 212, sliding rail 2121, control cylinder 213, inner membrane truss ring 22, left truss 221, right truss 222, force branch rod 223, guide rod 224, support 23, jack 24, operating platform 25, maintenance platform 26, template 3, roller 4, abutment frame 5, base 51, guide groove 511, pressure bearing seat 52, pressure bearing limit rod 521, torsion spring 522, and limit plate 523.

[0023] Example The basic implementation examples are as follows: Figures 1-11 As shown, a construction method for adjusting the tapering of a variable cross-section formwork includes the following steps: S1: Before pouring the concrete for the pier cap, measure and lay out the four corners of the pier column 1. Based on the positions of the four corners, locate the pre-embedded positions of the climbing rod 11. The pre-embedded positions are determined according to the position of the reinforcing bars of the pier column 1, and do not affect the installation of the main reinforcing bars and the sliding of the jack 24. According to the layout, the bolts are pre-embedded into the pier cap of the pier column 1. The base pipe and pressure plate are installed on the pier cap and fixed with bolts. Finally, the climbing rod 11 is installed in the base pipe and fixed. S2: The main reinforcement of pier column 1 can be made in lengths of 4.5m or 6m. After the first formwork of main reinforcement is installed, stirrups are installed at a height of 1.3m. S3: Determine the positioning line for the installation of the overall truss 2 on the pier and mark it; S4: Before installing the overall truss 2, pass the jacks 24 and self-locking devices through the pre-embedded climbing rods 11 to ensure consistent height and lock them in place; install the overall truss 2 using a crane, reserving space for the template 3 during installation, and install the brackets 23 on the overall truss 2, fixing the jacks 24 and self-locking devices to the brackets 23; finally, install the operating platform 25, safety railings, steel bar racks, hydraulic system operating console, and other auxiliary equipment; S5: The template 3 is pre-applied with release agent and installed between the overall truss 2 and the reinforcing steel. The four corners of the pier 1 are connected to the slots of the template 3 using rounded corner devices to ensure the integrity of the corners of the pier 1. S6: The first pour of concrete is 0.9m long, which serves as support for the entire formwork 3 system. 0.1m is reserved for the installation of the second-level formwork 3. The pouring should be carried out in layers, with each layer being 30 to 45 centimeters. After the concrete is poured, the surface should be roughened and the measurement should be repeated to confirm that the position of the pier 1 is correct. S7: After the concrete is poured, take advantage of the period when the concrete strength has not reached the lifting requirements of the overall truss 2 to carry out the installation of the reinforcement of the second layer of pouring segment. The installation height of the stirrups will not affect the position of the jack 24. S8: 12 hours after the concrete is poured, lift the entire truss 2 using jack 24. The first lifting stroke is 70 cm. During the lifting process, observe whether the formwork 3 is loose or slipping. If any is found, stop lifting immediately, then manually level it and analyze the cause of the slippage. Lifting can only continue after the problem is solved. After the lifting is completed, check and level it again to ensure installation accuracy. S9: After the first lift, the second layer of formwork 3 is installed. The second layer and the first layer of formwork 3 are sealed with an expansion agent to prevent grout leakage during concrete pouring. Then, concrete is poured and the outer formwork is lifted. This cycle of lifting is repeated until the 7th concrete pouring. S10: After the 7th concrete pouring is completed, the curing platform 26 is installed for the subsequent lifting of the formwork 3. At the same time, safety ladders, lifting channels, material hoists and other facilities are installed. After the installation is completed, the overall truss 2 assembly is completed and the normal continuous construction state is entered. S11: Based on the height of template 3, pour 0.7-0.9 meters each time, and carry out continuous 24-hour cycle construction. During the construction process, do a good job of concrete curing in accordance with the specifications.

[0024] like Figures 1-4As shown, the integral truss 2 includes an inner membrane truss ring 22 embedded inside the pier, an outer membrane truss ring 21 sleeved on the outside of the pier, and jacks 24 sleeved on the climbing rod 11. The inner membrane truss ring 22 and the outer membrane truss ring 21 are rigidly connected by jacks 24 to form the integral truss 2. An operating platform 25 and a maintenance platform 26 are respectively erected on the upper and lower parts of the integral truss 2, and a lifting channel is provided between the operating platform 25 and the maintenance platform 26. The inner and outer membrane truss rings are respectively connected to the pier. Templates 3 are laid between the pier walls. Each end of the template 3 is equipped with a plate and a slot. During installation, the slot of the template 3 is facing upward and the plate is facing downward. The template 3 is installed by inserting the plate into the slot. The template 3 is pre-assembled before concrete pouring. The integral truss 2 is equipped with rollers 4 facing the surface of the pier. The rollers 4 are used to press the template 3 against the pier body to be poured. The integral truss 2 is equipped with a buckle seat for assembling the rollers 4. Both ends of the rollers 4 are snapped into the buckle seat. The rollers 4 can rotate freely relative to the buckle seat.

[0025] like Figures 1-4 , Figure 7 As shown, three climbing rods 11 are symmetrically embedded on the outer sides of both long sides of pier 1, and two climbing rods 11 are symmetrically embedded on the inner sides of both long sides of pier 1. The climbing rods 11 on the long sides of pier 1 are all consistent with the slope of the long sides of pier 1. Two climbing rods 11 are symmetrically embedded on both short sides of pier 1, and the two climbing rods 11 are vertical to the short sides of pier 1. The inner membrane truss enclosure 22 includes a left truss 221 and a right truss 222 symmetrically arranged on both sides of the long side. The outer membrane truss enclosure 21 includes long trusses 211 located on both sides of the long side of the pier 1 and short trusses 212 located on both sides of the short side of the pier 1. The short trusses 212 span between the two long trusses 211 and are slidably connected to the long trusses 211. Jacks 24 are fitted on the climbing rods 11 on the outer sides of the long sides of the pier 1. The long trusses 211 are fixedly connected to the jacks 24 at these locations with brackets 23. The brackets 23 are arranged in an F-shape. The brackets 23 of the long trusses 211 are connected to the jacks 24 at these locations with the brackets 23. Jacks 24 are fixedly connected to the outer side of the long side; jacks 24 are also fitted onto the climbing rods 11 on the inner side of the long side of the pier 1, and F-shaped supports 23 are fixedly connected to the jacks 24 on the left and right trusses 222, respectively. The supports 23 of the left and right trusses 222 are fixedly connected to the jacks 24 on the inner side of the long side; jacks 24 are also fitted onto the climbing rods 11 on both sides of the short side of the pier 1, and F-shaped supports are fixedly connected to the short crossbeams corresponding to the jacks 24 on the short side. The support 23 of the short truss 212 is fixedly connected to the jack 24 on the short side; the jacks 24 on the outer side of the long side of the pier 1, the jacks 24 on the inner side of the long side of the pier 1, and the jacks 24 on both sides of the short side of the pier 1 are all fixedly connected by crossbeams to maintain the same horizontal plane, thereby realizing the rigid connection of the entire crossbeam through the jacks 24; the support 23 is equipped with a self-locking device, which includes hydraulic locks respectively set at the upper and lower ends of the jacks 24.

[0026] like Figures 5-6 As shown, the long truss 211 has symmetrical sliding grooves 2111 at both ends for the short truss 212 to pass through. The sliding grooves 2111 are equipped with fixed rails 2112 of ball bearing slide rails. The short truss 212 is equipped with sliding rails 2121. The long truss 211 and the short truss 212 are slidably connected by ball bearing slide rails. A control cylinder 213 is provided between the long truss 211 and the short truss 212. The cylinder body of the control cylinder 213 is fixed to the short truss 212, and the piston rod of the fixed cylinder is fixedly connected to the long truss 211.

[0027] like Figures 8-11 As shown, the inner membrane truss enclosure 22 also includes an abutment frame 5 connecting the short sides of the left and right trusses 222. The abutment frame 5 includes a base 51 and a bearing seat 52 fixed on the base 51. The left and right trusses 222 are vertically provided with guide rods 224. The base 51 has a guide groove 511 for the guide rods 224 to be inserted and slidably connected. The left and right trusses 222 form a grid for the base 51 to be inserted. The longitudinal height of the grid is consistent with the longitudinal height of the base 51, thereby ensuring that the base 51 will not be inserted. Relative to the vertical movement of the left and right trusses 222, the outer side of the base 51 is flush with the end faces of the left and right trusses 222 and is also equipped with rollers 4. The rollers 4 of the abutment frame 5 are used to abut against the template 3 of the inner short side of the pier. The pressure-bearing seat 52 is symmetrically and rotatably equipped with pressure-bearing limiting rods 521 on both sides. That is, rotating seats are symmetrically welded on both sides of the pressure-bearing seat 52, and columnar fixing rods are vertically fixedly welded on the rotating seats. The pressure-bearing limiting rods 521 are rotatably connected to the fixing rods. The pressure-bearing limiting rods 521 and the pressure-bearing seat 52 are connected to each other. The angled opening faces away from the pier 1. A torsion spring 522 is installed between the pressure-bearing limiting rod 521 and the rotating seat. The torsion spring 522 is used to rotate and unfold the pressure-bearing limiting rod 521 to both sides. Both left and right trusses 222 are vertically fixed with force-shaping rods 223. The force-shaping rods 223 are slidably sleeved on the pressure-bearing limiting rod 521. The cross-section of the force-shaping rod 223 is circular. The pressure-bearing limiting rod 521 has a straight groove for the force-shaping rod 223 to be inserted and slid. The radius of the arc segment inside the straight groove is the same as that of the force-shaping rod 223. The 3 cross-sectional circles have equal radii. When the pressure-bearing limiting rod 521 unfolds to both sides, it drives the two side force-bearing rods 223 to slide in opposite directions. When the two side force-bearing rods 223 slide in opposite directions, they drive the two side pressure-bearing limiting rods 521 to rotate in opposite directions. Limiting plates 523 are fixedly welded to both sides of the pressure-bearing seat 52. The rotation trajectory of the limiting plate 523 and the pressure-bearing limiting rod 521 intersects. When the pressure-bearing limiting rod 521 abuts against the limiting plate 523, the angle between the pressure-bearing limiting rod 521 and the abutting frame 5 is less than 180°.

[0028] In steps S8-S11, due to the slope on both sides of the long side of the high pier column 1, the distance between the left and right trusses 222 on both sides decreases during the climbing process. However, since the short side of the high pier column 1 is vertical and has no slope, the two ends of the short side of the left and right trusses are always connected to the template 3 through the roller 4. The force-bearing limit rod 521 and the force-bearing limit rod 223 connect the horizontal movement of the left and right trusses 222 with the rotation of the force-bearing limit rod 521. When the overall truss 2 is located at the bottom of the pier, the elastic element unfolds the force-bearing limit rod 521 on both sides. The force-bearing limit rod 521 rotates and unfolds to both sides, while driving the force-bearing limit rod 223 on both sides to move in opposite directions, thereby driving the left and right trusses 222 to move in opposite directions.

[0029] When the overall truss 2 is at the bottom, the pressure-bearing limiting rod 521 is in the extended state. The component of the pressure perpendicular to the template 3 is maximized and transmitted to the abutment frame 5. That is, the pressure on both sides of the template 3 is distributed to the middle to the maximum extent, reducing the stress concentration on both sides of the template 3. At the same time, it can resist the squeezing force of the outer membrane truss ring 21 and cement on the middle part of the template 3, thus ensuring that the short side template 3 does not break or deform. In addition, when the overall truss 2 climbs from the bottom to the top, firstly, the climbing rod 11 will drive the left and right trusses 222 on both sides to move closer to the middle. Secondly, the long sides on both sides also have an effect on the left and right trusses 222. The compressive force reduces the distance between the left and right trusses 222, causing them to slide automatically towards each other. The elastic element ensures the adaptive sliding of the left and right trusses 222. As the structure climbs, the pressure-bearing limit rods 521 rotate towards each other, and the angle between the pressure-bearing rods and the abutment frame 5 gradually decreases. This causes the vertical component of the force exerted by the left and right trusses 222 on the template 3 to gradually decrease. When the distance between the left and right trusses 222 decreases, the pressure exerted by the trusses on both sides of the template 3 and the pressure span of the middle part decrease. Therefore, the reduction in the component force can adapt to this state and prevent the risk of reverse deformation and breakage of the template 3 at higher elevations.

[0030] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A construction method for adjusting the tapering of a variable cross-section formwork, characterized in that, Includes the following steps: S1: Before pouring the concrete for the pier cap, measure and lay out the four corners of the pier column. Based on the positions of the four corners, locate the pre-embedded positions of the climbing rods. The pre-embedded positions are determined according to the positions of the pier column reinforcement bars and do not affect the installation of the main reinforcement bars and the sliding of the jacks. According to the layout, the bolts are pre-embedded into the pier cap of the pier column. The base pipe and pressure plate are installed on the pier cap and fixed with bolts. Finally, the climbing rod is installed in the base pipe and fixed. S2: The main reinforcement bars of the pier column can be made in lengths of 4.5m or 6m. After the first formwork of main reinforcement bars is installed, the stirrups are installed at a height of 1.3m. S3: Determine the positioning lines for the overall truss installation on the pier and mark them; S4: Before installing the overall truss, pass the jacks and self-locking devices through the pre-embedded climbing rods to ensure consistent height and lock them in place; install the overall truss using a crane, reserving space for the template during installation, installing supports on the overall truss, and fixing the jacks and self-locking devices to the supports; finally, install the operating platform, safety railings, steel bar racks, hydraulic system operating console, and other auxiliary equipment. S5: The template is pre-applied with release agent and installed between the overall truss and the reinforcing steel. The four corners of the pier are connected to the template slots using rounded corner devices to ensure the integrity of the pier corners. S6: The first pour of concrete is 0.9m long, which serves as support for the entire formwork system. 0.1m is reserved for the installation of the second-level formwork. The pouring should be carried out in layers, with each layer being 30 to 45 centimeters. After the concrete is poured, the surface should be roughened and the measurement should be repeated to confirm that the position of the pier column is correct. S7: After the concrete pouring is completed, the second layer of pouring segment steel reinforcement is installed during the period when the concrete strength has not reached the overall truss lifting requirements. The installation height of the stirrups will not affect the position of the jacks. S8: 12 hours after the concrete is poured, the entire truss is lifted by jacks. The first lifting stroke is 70 cm. During the lifting process, observe whether the formwork is loose or slipping. If any is found, the lifting should be stopped immediately, then the formwork should be manually leveled and the cause of slippage should be analyzed. The lifting can only continue after the cause of slippage is resolved. After the lifting is completed, the formwork should be inspected and leveled again to ensure the installation accuracy. S9: After the first lift, the second layer of formwork is installed. The second layer and the first layer of formwork are sealed with an expansion agent to prevent grout leakage during concrete pouring. Then, concrete is poured and the outer formwork is lifted. This cycle of lifting is repeated until the 7th concrete pouring. S10: After the 7th concrete pouring is completed, the curing platform will be installed for subsequent formwork lifting. At the same time, safety ladders, lifting channels, material hoists and other facilities will be installed. After the installation is completed, the overall truss assembly will be completed and the normal continuous construction state will begin. S11: Depending on the formwork height, pour 0.7-0.9 meters each time, and carry out continuous 24-hour cycle construction. During the construction process, perform concrete curing work in accordance with the specifications.

2. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 1, characterized in that: The self-locking device is installed on the bracket and includes hydraulic locks respectively located at the upper and lower ends of the jack.

3. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 1, characterized in that: The overall truss includes an inner membrane truss ring embedded inside the pier and an outer membrane truss ring fitted on the outside of the pier. Rollers are installed on the surface of the overall truss facing the pier, and the rollers are used to push the template against the pier body to be poured.

4. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 1, characterized in that: The inner membrane truss enclosure includes a left truss and a right truss symmetrically arranged on both sides of the long side, and an abutment frame connecting the short sides of the left and right trusses. The outer side of the abutment frame is flush with both ends of the short sides of the left and right trusses and is also equipped with rollers. The rollers of the abutment frame are used to abut against the template between the left and right trusses on the short side of the inner ring of the pier.

5. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 4, characterized in that: The left and right trusses are symmetrically and horizontally slidably connected to the two sides of the abutment frame. The abutment frame is symmetrically and rotatably equipped with pressure limiting rods on both sides. The angle opening between the pressure limiting rods and the abutment frame is away from the pier column. Both left and right trusses are vertically fixed with component rods. The component rods are slidably sleeved on the pressure limiting rods. An elastic element is provided between the pressure limiting rods and the abutment frame. The elastic element is used to make the pressure limiting rods unfold to both sides and drive the component rods on both sides to slide in opposite directions. When the component rods on both sides slide in opposite directions, they drive the pressure limiting rods on both sides to rotate in opposite directions.

6. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 5, characterized in that: The abutment frame is equipped with a limit plate. The rotation trajectory of the limit plate and the pressure limit rod intersects. When the pressure limit rod abuts against the limit plate, the angle between the pressure limit rod and the abutment frame is less than 180°.

7. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 6, characterized in that: The abutment frame includes a base, a pressure seat fixed to the base, a pressure limiting rod rotatably connected to both sides of the pressure seat, and an elastic element set as a torsion spring, which is connected between the pressure seat and the pressure limiting rod.

8. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 1, characterized in that: The outer membrane truss enclosure includes long trusses located on both sides of the long side of the pier and short trusses located on both sides of the short side of the pier. The short trusses span between the two long trusses and are slidably connected to the long trusses. The long trusses are guided by climbing rods on the long side, and the short trusses are guided by climbing rods on the short side.

9. The construction method for adjusting the tapering of a variable cross-section formwork according to claim 8, characterized in that: A control cylinder is installed between the long truss and the short truss. The cylinder body of the control cylinder is fixed to the short truss, and the piston rod of the fixed cylinder is fixedly connected to the long truss.

10. A construction method for adjusting the tapering of a variable cross-section formwork according to claim 9, characterized in that: The long truss has symmetrical sliding grooves at both ends for the short truss to pass through. The sliding grooves are equipped with fixed rails for ball bearing slides, and the short trusses are equipped with sliding rails. The long truss and the short truss are slidably connected by the ball bearing slides.

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