Variable cross-section pier construction method

Abstract

The present application relates to the field of variable cross-section pier construction, and discloses a variable cross-section pier construction method, comprising the following steps: step one, pouring the first section of the pier, installing a lifting frame and a side mold on the first section of the pier, the side mold comprising an adjustable formwork and two fixed formworks arranged vertically, the lower end of the adjustable formwork being provided with a rotating pull rod, the two ends of the rotating pull rod being rotatably connected to the two fixed formworks, the connection position of the rotating pull rod and the fixed formwork being adjustable, the lifting frame being horizontally slidably connected to a sliding block, the sliding block being slidably and vertically rotatably connected to a suspender, the suspender being provided with a sliding limiting portion at the upper end, and the lower end of the suspender being hingedly connected to the adjustable formwork; step two, pouring the pier, and the sliding block driving the adjustable formwork to be demolded; and step three, the lifting frame driving the adjustable formwork and the fixed formwork to ascend to the position of the next section of the pier to be poured, and the sliding block driving the adjustable formwork to approach the pier. The method can conveniently and quickly complete the construction and effectively improve the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of variable cross-section pier construction, and more specifically to a method for constructing variable cross-section piers. Background Technology

[0002] In bridge engineering, variable cross-section piers refer to piers whose cross-sectional dimensions or shapes change along the height direction. During the construction of such piers, each pouring section often requires a set of custom-made formwork, resulting in high formwork costs, low turnover rate, large storage area, and low overall construction efficiency.

[0003] As a typical variable cross-section pier, the tapered pier's cross-section changes uniformly along its height, tapering linearly at a certain slope in the transverse or longitudinal direction. Specifically, it can be categorized into single-sided slope, double-sided slope, and four-sided slope forms. To address the gradually changing cross-section of the tapered pier, existing technologies have employed modular formwork designs, adapting to changes in cross-sectional dimensions by removing excess modules. However, this type of formwork not only requires assembly on the ground, leading to cumbersome assembly operations, but also necessitates the removal of excess modules after each pour, significantly reducing construction efficiency and offering very limited improvement in overall construction efficiency.

[0004] Therefore, there is a need to provide a construction method for variable cross-section piers that can be completed quickly and easily, effectively improving construction efficiency. Summary of the Invention

[0005] The present invention aims to provide a construction method for variable cross-section piers, so as to facilitate and expedite construction and effectively improve construction efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a variable cross-section pier construction method, comprising the following steps: Step 1: Cast the first pier section. Install the lifting frame and side formwork on the first pier section. The lifting frame is used to lift the side formwork. The side formwork includes an adjustable template set at an inclination and two fixed templates set vertically. The lower end of the adjustable template is equipped with a rotating tie rod. The two ends of the rotating tie rod pass through the two fixed templates and are rotatably connected to the two fixed templates. The connection position between the rotating tie rod and the fixed templates is adjustable. The lifting frame is horizontally slidably connected to a slider, and a hanging rod is slidably and vertically rotatably connected to the slider. The hanging rod is equipped with a sliding limit part, which is used to prevent the upper end of the hanging rod from disengaging from the slider. The lower end of the hanging rod is hinged to the adjustable template. The slider is used to move the hanging rod and the upper end of the adjustable template closer to or away from the pier column. Step 2: Cast the pier column. The lower end of the adjustable template is rotatably connected to the rotating tie rod. The slider moves the adjustable template away from the pier column, and the lower end of the hanger rotates relative to the adjustable template until the slider and the sliding limit part contact. The slider continues to move away from the pier column, pulling the adjustable template to rotate around the rotating tie rod, thereby demolding the adjustable template. Step 3: The lifting frame lifts the adjustable template and the fixed template to the position of the next section of the pier to be poured. The slider moves the adjustable template closer to the pier. Adjust the connection position of the rotating rod and the fixed template so that the lower end of the adjustable template fits the poured pier.

[0007] The beneficial effects of this plan are: 1. The same set of adjustable and fixed templates is used for each casting. Only the position of the adjustable template needs to be adjusted to complete the casting of a pier column, which saves a lot of manpower and material resources and improves construction efficiency.

[0008] 2. Unlike existing methods that use a rigid, linear motion for demolding, this solution utilizes a slider, a hanger, and a rotating tie rod at the bottom of the adjustable template to form a lever mechanism. During demolding, the slider moves outward, first driving the adjustable template to rotate around its bottom, creating a wedge-shaped gap between the template panel and the concrete surface, achieving instantaneous, low-stress separation. Then, the entire template is pulled away. This series of actions completely solves the problem of concrete surface cracking or damage caused by sticking to the template, and eliminates the need for an additional high-thrust demolding device. The structure is ingenious and the operation is highly efficient.

[0009] 3. After the adjustable template is demolded, it becomes nearly vertical under the action of gravity. Therefore, the angle of the adjustable template needs to be readjusted before the first section of the pier is poured. The horizontally sliding slider is not only an actuator to adjust the inclination angle of the template to adapt to different cross-sectional slopes, but also drives the template to rotate and demold. A single drive source, through a clever mechanism connection, completes the two functions of "stepless slope change" and "rotation demolding" in a time-sharing manner, which greatly simplifies the system structure and significantly improves the continuity and automation of construction.

[0010] 4. The rotatable hinge point formed by the perforation in the fixed area of ​​the rotating tie rod and the fixed formwork plays two roles: during pouring, it is used to fix the bottom of the adjustable formwork and transmit the pressure from the bottom to the poured pier through the fixed formwork; during demolding, it becomes a reliable fulcrum for the rotation and peeling of the formwork. This design ensures that the lower edge of the adjustable formwork is always precisely aligned with the pier construction joint throughout the entire construction cycle, eliminating common quality defects such as misalignment and grout leakage at the source, which cannot be achieved by simply using a clamped fixed area or cantilever support.

[0011] 5. By precisely driving the slider with a motor, the accuracy of the upper positioning of the adjustable template is improved, thereby enhancing the template precision.

[0012] 6. When dismantling the formwork, there is no need to move the adjustable formwork horizontally too far. Due to the inclination of the pier side, the operating space between the adjustable formwork and the concrete will naturally increase after the formwork is lifted, so as to facilitate the next formwork installation.

[0013] 7. If the rotating tie rod is removed, the lower end of the adjustable template will sway during the lifting process, and it is easy to collide with the concrete and the operating platform under strong winds, resulting in damage to all three. In this solution, not only can the template be automatically demolded, but the adjustable template can also be prevented from swaying, and there is no need to fix the adjustable template separately, which is convenient and practical.

[0014] Furthermore, the fixed template is provided with a pouring area and a fixing area. The pouring area is located above the fixing area and is used as the template for the pier column to be poured. The fixing area is sandwiched on both sides of the poured pier column and is used to fix the fixed template. Several perforations are provided within the height range of the fixing area of ​​the two fixed templates. The rotating tie rod passes through the corresponding perforation and is rotatably connected to the perforation. The position of the several perforations is determined according to the design position of the lower end of the adjustable template during each pour.

[0015] Furthermore, the slider is provided with a horizontal rod, which passes through the slider and is rotatably connected to the slider. Each end of the horizontal rod is provided with a connecting hole, and two lifting rods pass through the connecting holes and are slidably connected to the connecting holes. Both lifting rods are perpendicular to the horizontal rod, and the sliding limit part is used to prevent the upper end of the lifting rod from coming out of the connecting hole.

[0016] Furthermore, the lifting frame includes a steel section unit, which serves as the slide rail for the slider. The steel section unit consists of two parallel channel steels arranged back to back. The slider is slidably mounted on the upper side of the two channel steels, and two rotating wheels are rotatably connected to the lower side of the slider. The two rotating wheels are respectively located on the web of the two channel steels. The two rotating wheels are used to clamp the two channel steels and roll on the web of the channel steels.

[0017] Furthermore, in step two, when the slider and the sliding limit part come into contact, the included angle between the hanging rod and the adjustable template is greater than 45°.

[0018] Furthermore, the side mold also includes several horizontal tie rods; In step one, two adjustable templates are set opposite each other on both sides of the pier. Each adjustable template is equipped with a reinforcement component, which includes an upper tie rod and two vertical back ribs. The two vertical back ribs are slidably set on both sides of the adjustable template, and the sliding direction is upward along the tilt direction of the adjustable template. The rotating pull rod passes through the lower end of the vertical back rib and is rotatably connected to the vertical back rib; The upper pull rod is connected to two fixed templates at both ends, and the upper pull rod is pressed against the upper ends of the two vertical back ribs; Several horizontal tie rods pass through the vertical back ribs of the two adjustable templates respectively. The horizontal tie rods are fixed by nuts and vertical back ribs, thereby achieving counter-pull for the two adjustable templates.

[0019] Furthermore, the upper pull rod includes a turnbuckle, with a wedge-shaped block at each end. A short pull rod is mounted on each wedge, passing through the fixed template and secured with a nut. The lower surface of the wedge is an inclined plane, and the upper surface of the vertical back rib is an inclined plane that mates with the lower surface of the wedge. The adjustable template also includes a limiting component to ensure that the vertical back rib can only slide along the direction of inclination of the adjustable template. The turnbuckle includes an adjusting rod, whose length can be adjusted by rotating it. In step one, after the rotating pull rod and the vertical back rib are rotatably connected, the upper pull rod is installed so that the wedge block presses against the vertical back rib downwards.

[0020] Furthermore, in step one, the installation method for the upper pull rod is as follows: 1.1 Lift the upper end of the vertical back rib and rotate the adjusting rod to extend the turnbuckle, so that the short tie rod of the wedge block passes through the fixed template on the corresponding side; 1.2 Lower the upper end of the vertical back rib, rotate the adjusting rod to shorten the turnbuckle, so that the lower surface of the wedge block and the upper surface of the vertical back rib abut against each other. Initially tighten the nut on the part of the short tie rod that passes through the fixed template, continue to rotate the adjusting rod to make the lower surface of the wedge block and the upper surface of the vertical back rib press against each other, and finally tighten the nut on the short tie rod.

[0021] Furthermore, the limiting component includes several limiting plates and several limiting bolts. The limiting plates are fixed on the adjustable template, and the limiting plates are all located on the side of the vertical back rib away from the corresponding fixed template. The limiting plates cooperate with the fixed template on the corresponding side to restrict the vertical back rib to slide only in the direction of the adjustable template's inclination. In step two, after the pier column is poured, the upper tie rod is removed first, and then the limiting plate and the vertical back brace are connected by the limiting bolt. The adjustable template is connected to the vertical back brace and the rotating tie rod by rotation.

[0022] This solution also has the following effects: 1. The positions of several perforations on the fixed area are pre-designed and located on the lower side of the adjustable template of each mold, so that the rotating tie rod can find the corresponding perforation and connection with the fixed template in each mold; the connection method of all tie rods in this solution is the same as that in the prior art, which is: "after passing the end of the tie rod through the template, a washer is put on the end of the tie rod and the nut is tightened". If the spacing between the perforations is too small, several perforations will be connected to form a strip hole, which is also a special case of claim 1. The strip hole is a subordinate description of several perforations.

[0023] 2. If the direction of the pulling force is not ideal during demolding, a vertical component force will be generated, which may cause the template to lift and scratch the concrete. This solution clarifies the ideal geometric relationship at the moment of demolding pull: when the slider contacts the sliding limit part and begins to pull the template, the angle between the lifting rod and the adjustable template is greater than 45°, and as close to 90° as possible to ensure that sufficient horizontal pulling force can be generated for demolding.

[0024] 3. In existing technologies, the back bracing of pier columns is usually set horizontally, like a clamp to maintain the design alignment of the outer side of the formwork. When wind loads, eccentric casting, or vibration cause local impacts, the back bracing with sufficient stiffness can resist uneven forces and prevent the formwork from becoming unstable and twisted.

[0025] However, since this solution is applicable to variable cross-section piers, after adjusting the adjustable position, the two sides of the fixed template will inevitably protrude relative to the adjustable template. If horizontal back ribs are used, it is not possible to directly connect the back ribs on both sides of the corner with nuts and tie rods as in existing technologies. Naturally, it is also not possible to support the template like a clamp to prevent template deformation. The corner position is the most prone to template deformation, and reinforcement here is essential.

[0026] In this solution, by changing the direction of the back ribs and setting vertical back ribs (here, vertical refers to setting them upwards along the direction of the adjustable template, not absolutely vertical), and setting upper tie rods and rotating tie rods on the upper and lower sides of the vertical back ribs respectively, a frame structure is formed; then the upper tie rods and rotating tie rods pass through the fixed template and are connected to the fixed template, so that the vertical back ribs can stabilize both sides of the adjustable template and prevent the edges of the adjustable template from deforming.

[0027] 4. When the horizontal tie rod passes through the vertical back rib with greater stiffness, since both the adjustable template and the vertical back rib are inclined, the horizontal tie rod will generate an upward component force along the inclined plane, causing the back rib to slide upward. In this solution, by setting turnbuckles and wedge blocks, the wedge blocks are pulled in advance by the turnbuckles, thereby pressing the back rib downward and preventing the impact and instability caused by the sudden sliding of the back rib.

[0028] 5. The limiting plate can not only cooperate with the fixed template on the corresponding side to restrict the vertical back rib to slide only in the direction of the adjustable template's tilt; it can also connect with the vertical back rib during demolding. At this time, even if the upper pull rod is removed, the back rib can still be fixed. Demolding can be achieved directly by sliding the slider without removing the back rib, and there is no need to reinstall the back rib after it is lifted into place, which is convenient, quick, and improves construction efficiency. Attached Figure Description

[0029] Figure 1 Flowchart for an embodiment; Figure 2 A three-dimensional diagram of an embodiment; Figure 3 A three-dimensional view of the adjustable template for an embodiment; Figure 4 The main view of the adjustable template in this embodiment; Figure 5 This is a front view of the adjustable template after reinforcement, as shown in the embodiment. Figure 6 for Figure 5Sectional view along axis AA; Figure 7 This is a front view of the example before pouring; Figure 8 This is a front view of the sliding limit part and the slider after they come into contact during demolding in an embodiment. Figure 9 This is the front view of the embodiment after demolding; Figure 10 This is a schematic diagram of the slider after being reset following the upgrade in the embodiment. Detailed Implementation

[0030] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings of the instruction manual include: 1. Rotating tie rod; 2. Fixed template; 3. Adjustable template; 4. Pier column; 5. Hanging rod; 6. Slide rail steel unit; 7. Through hole; 8. Sliding block; 9. Horizontal rod; 10. Sliding limit part; 11. Vertical shaft; 12. Rotating wheel; 13. Through-hole jack; 14. Module; 15. Horizontal rib; 16. Vertical rib; 17. Rectangular area; 18. Ear plate; 19. Limiting plate; 20. Horizontal tie rod; 21. Pad block; 22. Vertical strip hole; 23. Vertical back rib; 24. Turnbuckle; 25. Adjusting rod; 26. Tie rod; 27. Short tie rod; 28. Wedge block; 29. ​​Limiting bolt.

[0031] Example Construction method of variable cross-section pier column 4, flowchart as follows: Figure 1 As shown, this method is applicable to conical piers with two inclined surfaces forming an isosceles trapezoid, and includes the following steps: Step 1: Cast the first section of pier column 4. Install the lifting frame and side formwork on the first section of pier column 4. The lifting frame adopts the lifting frame in patent CN116927099B. The lower end of the lifting frame is connected to the cast section of pier column 4. The lifting frame includes two horizontally arranged steel units that are perpendicular to each other. Each steel unit includes two back-to-back and parallel channel steels. Several hanging rods 5 are provided on the steel units. The hanging rods 5 are used to connect with the formwork. The ends of the steel units are bolted to the operating platform. The two ends of one steel unit correspond to two fixed formwork 2, and the two ends of the other steel unit correspond to two adjustable formwork 3. In this embodiment, the steel unit corresponding to the adjustable formwork 3 is defined as the sliding rail steel unit 6. The operating platform is set on the periphery of the formwork to provide an operating platform for the staff. For ease of display, the operating platform is hidden in the drawings of this patent. The relevant features of the lifting frame will not be described in detail.

[0032] The side mold includes two vertically arranged fixed templates 2 and an inclined adjustable template 3, such as... Figure 2As shown, the fixed template 2 has a pouring area and a fixing area. The pouring area is located above the fixing area and serves as the pouring template for the pier 4 to be poured. The fixing area is sandwiched between the two sides of the already poured pier 4 and is used to fix the fixed template 2. Several perforations 7 are provided within the height range of the fixing areas of the two fixed templates 2. The rotating tie rod 1 is used to pass through the perforations 7 and rotate to connect with the bottom of the adjustable template 3. Depending on the actual situation, if the spacing between the perforations 7 is small, several perforations 7 can also be connected to form a strip hole. The number of perforations 7 is determined according to the number of times the pier 4 is poured, and the position of the perforations 7 is determined according to the position of the lower end of the adjustable template 3 during each pour. In this embodiment, several perforations 7 are provided on both sides of the fixed template 2. Since the pier 4 needs to be poured four times using the template, the number of perforations 7 on each side is 4. Each time it is poured, the adjustable template 3 needs to be moved inward to adapt to the change in the cross-section of the pier 4. Therefore, the perforations 7 connected by the rotating tie rod 1 need to be adjusted to the center line of the fixed template 2 once. Since the perforations 7 are within the height range of the fixing area, the poured concrete will not leak out from the perforations 7. In this solution, the connection method of all the ends of the tie rods 26 is the same as that of the tie rods 26 in the prior art. All of them are tightened with nuts at the ends of the tie rods 26 to press against the template and achieve the pull of the templates on both sides. Figure 2 This is for illustrative purposes only. The reinforcement structure of the template and the specific connection structure between the templates are omitted. The main focus is on showing the positional relationship between the pier 4, the lifting frame, the adjustable template 3 and the fixed template 2.

[0033] A rectangular slider 8 is horizontally slidably connected to the slide rail steel unit 6. A horizontal rod 9 is rotatably connected to the slider 8. The horizontal rod 9 passes through the slider 8 and is perpendicular to the slide rail steel unit 6. A connecting hole is opened at each end of the horizontal rod 9. Two hangers 5 pass through the connecting holes and are slidably connected to the connecting holes. Both hangers 5 are perpendicular to the horizontal rod 9. A sliding limit part 10 is used to prevent the upper end of the hanger 5 from coming out of the connecting hole. In this embodiment, the sliding limit part 10 is a nut welded to the hanger 5. The sliding limit part 10 cannot pass through the connecting hole. The slider 8 protrudes from both sides relative to the slide rail steel unit. A vertical shaft 11 is integrally formed on the lower surface of both protrusions. A rotating wheel 12 is sleeved on the vertical shaft 11. The rotating wheel 12 is rotatably connected to the vertical shaft 11. The two rotating wheels 12 are clamped against the web of the channel steel on both sides of the slide rail steel unit 6, thereby playing a guiding role. In this embodiment, a driving component is also included, which is at least one servo motor (not shown in the figure). The servo motor is a small servo motor, such as the MBDV series model from Mingzhi. The servo motor is connected to one of the rotating wheels 12 by a sliding bolt. The upper end of the output shaft of the servo motor is bolted to the lower end of the vertical shaft 11. The connection method between the motor and the rotating shaft is existing technology and will not be described in detail. The servo motor is used to drive the rotating wheel 12 to roll on both sides of the slide rail steel unit 6. Several protruding strips are integrally formed at corresponding positions on the rotating wheel 12 and the slide rail steel unit 6 to prevent slippage.

[0034] As an improvement, the driving component can also be two horizontally arranged cylinders (not shown in the figure). The specific fixed height of the two cylinders can be adjusted according to the actual situation. The two cylinders are bolted to both sides of the slide rail steel unit 6. The output shafts of the two cylinders and the slider 8 are bolted to the protruding part of the slide rail steel unit, or the output shafts of the two cylinders are connected to the vertical shaft 11 to facilitate the horizontal movement of the slider 8. In general, the cylinders are fixed on the upper surface of the slide rail steel unit 6. However, since the lifting frame is usually equipped with a through-hole jack 13, which is used to drive the lifting frame to climb on the pole, and the through-hole jack 13 is usually set on the slide rail steel unit 6, the through-hole jack 13 and the cylinder are prone to spatial interference. Therefore, it is necessary to move the cylinders to both sides of the slide rail steel unit 6.

[0035] like Figure 3 , Figure 4 As shown, the adjustable template 3 consists of four horizontally arranged modules 14 arranged from top to bottom. Each module 14 includes horizontal ribs 15 on the upper and lower sides and vertical ribs 16 between the horizontal ribs 15. The horizontal ribs 15 are the main load-bearing ribs, and their thickness and height are greater than those of the vertical ribs 16. The combination of the horizontal ribs 15 and the vertical ribs 16 divides the surface of the module 14 into several rectangular areas 17. The four modules 14 are vertically assembled, and the horizontal ribs 15 at the assembly position are bolted together (bolts are not shown in the figure). The uppermost module 14 has two ear plates 18 integrally formed on the upper side of the horizontal ribs 15. Each ear plate 18 has a hole. The lower end of the hanger 5 has an integrally formed pivot. The pivot passes through the ear plates 18 and is rotatably connected to the ear plates 18. The structure to prevent the pivot from falling out is existing technology, which can be achieved by setting a protruding structure, and will not be described in detail. A limiting plate 19 is welded into the rectangular areas 17 on the left and right sides of the topmost module 14, and a limiting plate 19 is also welded into the rectangular areas 17 on the left and right sides of the bottommost module 14.

[0036] It also includes several horizontal tie rods 20 and pads 21, with two adjustable templates 3 arranged opposite each other on both sides of the pier 4, such as Figure 5 , Figure 6 As shown, the adjustable template 3 is equipped with a reinforcement component, which includes an upper pull rod 26 and two vertical back ribs 23. The two vertical back ribs 23 are used to reinforce both sides of the adjustable template 3 and support it on the horizontal rib 15. The vertical back ribs 23 are set between the limiting plate 19 and the fixed template 2, so as to ensure that the vertical back ribs 23 can only slide in the direction of the tilt of the adjustable template 3. The rotating pull rod 1 passes through the lower end of the vertical back rib 23 and is rotatably connected to the vertical back rib 23. The limiting plate 19 is detachably connected to the vertical back rib 23 through the limiting bolt 29. The vertical back rib 23 has several vertical strip holes 22 for the horizontal pull rod 20 to pass through.

[0037] The upper pull rod 26 includes a turnbuckle 24, which is existing technology. It includes an adjusting rod 25, with a pull rod 26 threaded to each end of the adjusting rod 25. When the adjusting rod 25 is rotated, the two pull rods 26 simultaneously move closer to or further away from the turnbuckle 24, thereby adjusting the length of the turnbuckle 24 to achieve tightening or loosening. A wedge block 28 is welded to the end of each pull rod 26 at both ends of the turnbuckle 24. A short pull rod 27 is welded to the side of the wedge block 28 away from the turnbuckle 24. The short pull rod 27 passes through the fixed template 2 and is fixed with a nut. The lower surface of the wedge block 28 is an inclined surface sloping towards the centerline of the adjustable template 3, and the upper end of the vertical back rib 23 is an inclined surface that matches the lower surface of the wedge block 28. When the length of the turnbuckle 24 is shortened, the wedge block 28 presses downward against the vertical back rib 23.

[0038] Several horizontal tie rods 20 pass through the adjustable template 3, the vertical back rib 23 and the pad 21 at both ends in sequence, and are finally fixed by tightening the nut, so as to pull the two adjustable templates 3 against each other; the pad 21 is inclined and fits against the surface of the adjustable template 3 on the side close to the adjustable template 3, and the other side is a vertical surface, which is used to provide support for the nut. The contact surface of the pad 21 and the adjustable template 3 is integrally formed with anti-slip ridges. The ridges are conventional and will not be described in detail.

[0039] The specific installation process of the side mold is as follows: like Figure 7 As shown, four templates are used to enclose the pier column 4 of the section to be poured. Two adjustable templates 3 are set opposite each other on both sides of the pier column 4. Reinforcing components are installed on the adjustable templates 3. The rotating tie rod 1 passes through the lower end of the vertical back rib 23 and is rotatably connected to the vertical back rib 23. The two ends of the rotating tie rod 1 are tightened by nuts and the fixed templates 2 on both sides. The upper tie rod 26 is installed. Several horizontal tie rods 20 pass through the vertical back ribs 23 of the two adjustable templates 3 respectively. The horizontal tie rods 20 are fixed by nuts and the vertical back ribs 23, thereby achieving mutual tension between the two adjustable templates 3. PVC pipes are fitted on the horizontal tie rods 20 for easy removal after pouring.

[0040] The installation method for the upper pull rod 26 is as follows: 1.1 Lift the upper end of the vertical back rib 23 and rotate the adjusting rod 25 to extend the turnbuckle 24, so that the short tie rod 27 of the wedge block 28 passes through the fixed template 2 on the corresponding side; 1.2 Lower the upper end of the vertical back rib 23, rotate the adjusting rod 25 to shorten the turnbuckle 24, so that the lower surface of the wedge block 28 abuts against the upper surface of the vertical back rib 23, initially tighten the nut on the part of the short pull rod 27 that protrudes from the fixed template 2, continue to rotate the adjusting rod 25 to make the lower surface of the wedge block 28 abut against the upper surface of the vertical back rib 23, and finally tighten the nut on the short pull rod 27.

[0041] Step 2: Cast the pier column 4. First, remove the upper tie rod 26, then fix the limiting plate 19 and the vertical back rib 23 together with the limiting bolt 29. The adjustable template 3 is rotatably connected to the vertical back rib 23 and the rotating tie rod 1. Figure 8 As shown, slider 8 moves adjustable template 3 away from pier 4, and the lower end of hanger 5 rotates relative to adjustable template 3 until slider 8 contacts sliding limit part 10; at this time, the included angle between hanger 5 and adjustable template 3 is greater than 45°; Figure 9 As shown, the slider 8 continues to move away from the pier 4, pulling the adjustable template 3 to rotate around the rotating rod 1, thereby demolding the adjustable template 3; the tilt angle of the adjustable template 3 in the figure is only for illustration. In reality, there is also an operating platform on the outside of the template. The adjustable template 3 can be rotated until it contacts the operating platform.

[0042] Step 3, as follows Figure 10 As shown, the lifting frame raises the adjustable template 3 and the fixed template 2 to the position of the next section of the pier column 4 to be poured. The slider 8 moves the adjustable template 3 closer to the pier column 4, so that the upper end of the adjustable template 3 reaches the design position for the next pour. Tie the upper end of the wire rope to the slide rail steel unit 6 and the lower end to the lower end of the hanger 5 to temporarily fix the height of the upper end of the adjustable template 3. Remove the rotating tie rod 1 at the lower end of the adjustable template 3 and move it to the design position for the next pour. Tighten the nut to fix it. If the adjacent perforations 7 have been connected to form a strip hole, there is no need to use the wire rope. Simply loosen the nut to push the rotating tie rod 1 to the design position for the next pour, so that the lower end of the adjustable template 3 fits against the already poured pier column 4. Remove the limit bolt 29 and repeat step 1 to perform the next pour.

[0043] 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 variable cross-section piers, characterized in that, Includes the following steps: Step 1: Cast the first pier section. Install the lifting frame and side formwork on the first pier section. The lifting frame is used to lift the side formwork. The side formwork includes an adjustable template set at an inclination and two fixed templates set vertically. The lower end of the adjustable template is equipped with a rotating tie rod. The two ends of the rotating tie rod pass through the two fixed templates and are rotatably connected to the two fixed templates. The connection position between the rotating tie rod and the fixed templates is adjustable. The lifting frame is horizontally slidably connected to a slider, and a hanging rod is slidably and vertically rotatably connected to the slider. The hanging rod is equipped with a sliding limit part, which is used to prevent the upper end of the hanging rod from disengaging from the slider. The lower end of the hanging rod is hinged to the adjustable template. The slider is used to move the hanging rod and the upper end of the adjustable template closer to or away from the pier column. Step 2: Cast the pier column. The lower end of the adjustable template is rotatably connected to the rotating tie rod. The slider moves the adjustable template away from the pier column, and the lower end of the hanger rotates relative to the adjustable template until the slider and the sliding limit part contact. The slider continues to move away from the pier column, pulling the adjustable template to rotate around the rotating tie rod, thereby demolding the adjustable template. Step 3: The lifting frame lifts the adjustable template and the fixed template to the position of the next section of the pier to be poured. The slider moves the adjustable template closer to the pier. Adjust the connection position of the rotating rod and the fixed template so that the lower end of the adjustable template fits the poured pier.

2. The construction method for variable cross-section piers according to claim 1, characterized in that: The fixed template has a pouring area and a fixing area. The pouring area is located above the fixing area and is used as the template for the pier column to be poured. The fixing area is sandwiched on both sides of the poured pier column and is used to fix the fixed template. Several perforations are provided within the height range of the fixing areas of the two fixed templates. The rotating tie rod passes through the corresponding perforation and is rotatably connected to the perforation. The position of the several perforations is determined according to the design position of the lower end of the adjustable template during each pour.

3. The construction method for variable cross-section piers according to claim 2, characterized in that: The slider is equipped with a horizontal rod that passes through the slider and is rotatably connected to it. Each end of the horizontal rod has a connecting hole, and two lifting rods pass through the connecting holes and are slidably connected to them. Both lifting rods are perpendicular to the horizontal rod. A sliding limit part is used to prevent the upper end of the lifting rod from coming out of the connecting hole.

4. The construction method for variable cross-section piers according to claim 3, characterized in that: The lifting frame includes a steel section unit, which serves as the slide rail for the slider. The steel section unit consists of two parallel channel steels arranged back to back. The slider is slidably mounted on the upper side of the two channel steels, and two rotating wheels are rotatably connected to the lower side of the slider. The two rotating wheels are respectively located on the web of the two channel steels. The two rotating wheels are used to clamp the two channel steels and roll on the web of the channel steels.

5. The construction method for variable cross-section piers according to claim 4, characterized in that: In step two, when the slider and the sliding limit part come into contact, the included angle between the hanging rod and the adjustable template is greater than 45°.

6. The construction method for variable cross-section piers according to claim 5, characterized in that: The side formwork also includes several horizontal tie rods; In step one, two adjustable templates are set opposite each other on both sides of the pier. Each adjustable template is equipped with a reinforcement component, which includes an upper tie rod and two vertical back ribs. The two vertical back ribs are slidably set on both sides of the adjustable template, and the sliding direction is upward along the tilt direction of the adjustable template. The rotating pull rod passes through the lower end of the vertical back rib and is rotatably connected to the vertical back rib; The upper pull rod is connected to two fixed templates at both ends, and the upper pull rod is pressed against the upper ends of the two vertical back ribs; Several horizontal tie rods pass through the vertical back ribs of the two adjustable templates respectively. The horizontal tie rods are fixed by nuts and vertical back ribs, thereby achieving counter-pull for the two adjustable templates.

7. The construction method for variable cross-section piers according to claim 6, characterized in that: The upper pull rod includes a turnbuckle, with a wedge-shaped block at each end. A short pull rod is mounted on each wedge, passing through the fixed template and secured with a nut. The lower surface of the wedge is inclined, and the upper surface of the vertical back rib is also inclined, matching the lower surface of the wedge. The adjustable template also includes a limiting component to ensure that the vertical back rib can only slide along the direction of the adjustable template's inclination. The turnbuckle includes an adjusting rod; rotating the adjusting rod adjusts the length of the turnbuckle. In step one, after the rotating pull rod and the vertical back rib are rotatably connected, the upper pull rod is installed so that the wedge block presses against the vertical back rib downwards.

8. The construction method for variable cross-section piers according to claim 7, characterized in that: In step one, the installation method for the upper pull rod is as follows: 1.1 Lift the upper end of the vertical back rib and rotate the adjusting rod to extend the turnbuckle, so that the short tie rod of the wedge block passes through the fixed template on the corresponding side; 1.2 Lower the upper end of the vertical back rib, rotate the adjusting rod to shorten the turnbuckle, so that the lower surface of the wedge block and the upper surface of the vertical back rib abut against each other. Initially tighten the nut on the part of the short tie rod that passes through the fixed template, continue to rotate the adjusting rod to make the lower surface of the wedge block and the upper surface of the vertical back rib press against each other, and finally tighten the nut on the short tie rod.

9. The construction method for variable cross-section piers according to claim 8, characterized in that: The limiting assembly includes several limiting plates and several limiting bolts. The limiting plates are fixed on the adjustable template. The limiting plates are all located on the side of the vertical back rib away from the corresponding fixed template. The limiting plates cooperate with the fixed template on the corresponding side to restrict the vertical back rib to slide only in the direction of the adjustable template. In step two, after the pier column is poured, the upper tie rod is removed first, and then the limiting plate and the vertical back brace are connected by the limiting bolt. The adjustable template is connected to the vertical back brace and the rotating tie rod by rotation.

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