Movable formwork for large-span and large-longitudinal-slope beam bridge and construction method of movable formwork

Abstract

The invention discloses a movable formwork for a large-span and large-longitudinal-slope beam bridge, and relates to the technical field of bridge construction, the movable formwork comprises a main truss frame, the main truss frame is connected through high-strength bolts to form a double-girder structure, a main truss lower chord frame fixes an outrigger through bolts, and the outrigger is placed on the top surface of a main truss upper chord member and is in bolted connection with the lower chord frame. According to the movable formwork for the large-span and large-longitudinal-slope beam bridge and the construction method of the movable formwork, through targeted structural improvement and process innovation, breakthrough of the problems of formwork horizontal force transmission, pre-camber accurate adjustment, construction joint slab staggering control and the like is achieved, and the construction quality and efficiency are remarkably improved; according to the movable formwork, the structure is reasonable, all parts act synergistically, the stability and the bearing capacity of the formwork are ensured, the characteristics of construction loads and the large span and the large gradient of a bridge are fully considered, the formwork can adapt to the complex construction environment, and the phenomenon of slab staggering of construction joints is relieved by optimizing a formwork supporting system.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a mobile formwork for a large-span and large-longitudinal-slope beam bridge and a construction method thereof. Background Art

[0002] In the field of bridge engineering, the construction of beam bridges with large spans and large longitudinal slopes has long faced challenges in complex working conditions. Take the Pangani Bridge in Tanzania, Africa, for example. The bridge is 525 meters long and adopts a span arrangement of (52.5+60×7+52.5)m. The maximum longitudinal slope is 6.65%, and it is located on a circular curve with a vertical curve radius of 3968m. The construction of such bridges needs to take into account the longitudinal slope, curve line shape and structural stability. Traditional construction methods such as the top-pushing method have the problems of large equipment investment and difficult line shape control. The cast-in-place method of the bracket is restricted by the terrain and has poor economic efficiency. The prefabricated erection of the bridge erection machine is difficult to adapt to the positioning of the beam under the large longitudinal slope. Although the mobile formwork cast-in-place method has the characteristics of high efficiency and strong adaptability, it still faces key technical bottlenecks such as the horizontal force transmission of the formwork, precise adjustment of the pre-camber, and control of the misalignment of the construction joint under the working conditions of large spans, steep longitudinal slopes and vertical curves. Targeted structural improvements and process innovations are urgently needed.

[0003] The existing mobile formwork technology is mostly designed for small spans, gentle longitudinal slopes or small radius curves. When applied to large span, large longitudinal slope vertical curve bridges, significant defects are exposed: first, the conventional pre-camber setting adopts a single adjustment method, which cannot effectively decompose the deformation compensation of the fixed section and the movable section, resulting in excessive adjustment of the outer formwork support rod and insufficient precision; second, the horizontal force transmission of the formwork through the hole state depends on simple anchoring, which is easy to cause leg slippage or pier bias in longitudinal slopes above 6%; third, the risk of driving wheel slippage of the gantry system is high when traveling on steep slopes, and the existing rubber tire and steel wheel combination has not been verified by heavy load under a 6% slope; fourth, the control of construction joint misalignment mostly relies on later repairs, and does not start from the optimization of the formwork support system, resulting in excessive deflection of the elastic formwork bed. In addition, the formwork load increases dramatically during large span construction, and the traditional structure requires temporary reinforcement of the bridge pier, which significantly weakens the economic advantage of the mobile formwork. In this regard, we propose a mobile formwork and construction method for large span and large longitudinal slope beam bridges. Summary of the invention

[0004] In order to solve the above technical problems, a mobile formwork and a construction method thereof for a large-span and large-longitudinal-slope beam bridge are provided. This technical solution solves the above problems.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A mobile formwork for a large-span and large-slope beam bridge, comprising a main truss frame, the main truss frame is connected by high-strength bolts to form a double-main-beam structure, the main truss lower chord frame is fixed with a cantilever beam by bolts, the cantilever beam is placed on the top surface of the main truss upper chord rod and is bolted to the lower chord frame;

[0007] The hanging crank arm is hung in the cantilever beam slide mechanism, the slide is connected to the cantilever beam buckle device through a pin shaft, and the crank arm is fixed in position through a limit structure and bolts;

[0008] The outer mold is connected to the bottom hinge seat of the hanging crank arm through a screw rod, the front load-bearing leg is supported on the rod column frame through an ultra-high pressure oil cylinder, and the leg crossbeam trolley slide seat is slidably matched with the longitudinal movement channel of the lower chord of the main truss;

[0009] The column frame is composed of a hoop and a tie rod and is anchored to the bridge pier through precision-rolled threaded steel bars;

[0010] The front auxiliary outrigger is hinged to the front end of the main truss, the bottom is anchored to the front pier support beam through high-strength precision-rolled threaded steel, and the top is connected to the lower chord of the guide beam through a balance hinge;

[0011] The inner mold is connected and fixed to the end mold by bolts, the hydraulic system connects the pump station and the oil cylinder through a high-pressure hose, the electrical system supplies power to the gantry crane through a cable reel, the main power cabinet distributes power through the distribution box, the gantry crane runs on the upper chord track of the main truss, and moves through a half-tire and half-steel wheel mechanism, the electric hoist is connected to the hook through a steel wire rope, the anti-slip device is locked with the main truss longitudinal displacement orifice plate through a pin shaft, and the rod column is rotated and the safety rope is hung when it is reversed.

[0012] Preferably, it also includes a template part, wherein the arching line of the template part is carried out according to the characteristics of a quadratic parabola, the mid-span arching range is 33-250mm, the fixed arching range of the cantilever beam is 16-130mm, and the remaining part is adjusted by the movable screw rod of the outer mold support rod.

[0013] Preferably, the running wheels of the small gantry crane adopt a combination of 1 / 2 steel wheel + 1 / 2 rubber tire and are all-wheel drive. Before use, a test platform with a slope of 6% needs to be set up to carry out a simulation test of the small gantry crane's empty and heavy-load running on a large longitudinal slope to test its climbing and braking capabilities.

[0014] A construction method for a mobile formwork for a large-span and large-slope beam bridge, used to realize the mobile formwork for the large-span and large-slope beam bridge, comprising the following steps:

[0015] S1, construction preparation stage, the construction preparation stage includes: installing precision rolled threaded steel hangers, installing pier top loose formwork, tying bottom web reinforcement, installing inner formwork, tying top plate reinforcement and installing end formwork;

[0016] S2, concrete pouring and curing stage, the concrete pouring and curing stage includes: pouring concrete and curing;

[0017] S3, the template removal and tensioning stage, the template removal and tensioning stage includes: removing the inner formwork and the end formwork, tensioning the concrete beam body and removing the loose formwork on the pier top;

[0018] S4, the mobile formwork cycle construction process stage, the mobile formwork cycle construction process stage includes: dropping the formwork and removing the hanger, overall mold opening, reversing the legs, longitudinally moving through the hole, adjusting the formwork, closing the formwork and locking. After locking the formwork position, enter the next span construction cycle.

[0019] Preferably, the specific steps of the movable mold frame in the mold closing casting state are:

[0020] After closing the mold, connect the rear end of the bottom mold to the old concrete;

[0021] After the bottom formwork at the middle pier is supported against the pier pad stone, the bottom formwork at both ends of the middle pier is connected with threaded steel bars;

[0022] Finally, the bottom formwork at the front end of the cantilever end is connected to the longitudinal displacement channel of the main truss.

[0023] Preferably, the movable mold frame in the mold opening and hole-passing state specifically includes:

[0024] When the mold frame is moving, adjust the working pressure of the hydraulic system to balance the thrust of the longitudinal cylinder and the friction force when the mold frame moves;

[0025] An anti-slip device and an anchoring device are installed on the outriggers. When the outrigger longitudinal movement cylinders are reversed, the anti-slip device is locked with the lower chord of the main truss.

[0026] Use the long-stroke cylinders of the front and rear auxiliary legs to adjust the slope of the formwork: before the front auxiliary legs reach the advance pier, adjust the formwork to be parallel to the current span; after the front auxiliary legs reach the advance pier, adjust the elevations of the front and rear auxiliary legs to make the formwork parallel to the next span.

[0027] Preferably, in step S2, the concrete pouring working condition is: the weight of the concrete is transmitted by: formwork - hanging crank arm - hanger - main truss - load-bearing leg - lifting cylinder, and finally to the bridge deck and the pier top. During pouring, the formwork is closed to form a concrete pouring space and then concrete pouring is carried out.

[0028] Preferably, in step S4, the specific working conditions of mold dropping and mold opening are: releasing the locking device between the mold bed and the bridge pier and the main truss, removing the vertical constraint of the mold frame, and completing the mold dropping; after the mold dropping, removing the threaded steel bar hanger rod, the center seam bolt of the hanging crank arm and the connecting bolt of the center seam of the bottom mold, removing the lateral constraint of the mold frame, and completing the mold opening work;

[0029] The leg-reversing working conditions include: the rear load-bearing leg reverse transportation: after the formwork is opened and jacked up, it is supported by the rear auxiliary legs and the front load-bearing legs, and the rear load-bearing legs are reversed to the front end of the poured concrete beam for installation through the longitudinal cylinder; the front load-bearing legs and rod columns are reversed for the first time: after the installation of the rear load-bearing legs is completed, they are supported by the rear auxiliary legs and the rear load-bearing legs, and the front load-bearing legs and rod columns are reversed to the designated position of the cantilever end of the poured beam through the longitudinal cylinder, and anchored to the beam surface using the rod column frame beam support;

[0030] The specific working conditions of longitudinal movement through the hole are as follows: after the formwork is inverted, it is pushed forward by the longitudinal movement cylinders of the front and rear load-bearing legs; the front auxiliary legs are lifted to support the front pier support beam, and the front load-bearing legs and rods are transported backward to the front pier for installation and anchoring; the formwork is moved forward again, and after the rear auxiliary legs are folded, it continues to be longitudinally moved to the standard casting position of the lower span; finally, the rear auxiliary legs and the rear load-bearing legs are transported backward to the support position of the next span;

[0031] The specific working conditions of mold closing and mold adjustment are as follows: push the hanging crank arm and the outer mold plate inward through the mold opening hydraulic cylinder; complete the connection of the center seam of the bottom mold, the center seam bolts of the hanging crank arm and the precision-rolled threaded hanger rod; use the outrigger lifting cylinder to lift the mold bed as a whole, and adjust the mold bed elevation and center line to the casting state.

[0032] Preferably, in order to alleviate the misalignment of the construction joint, in the steps, the rear load-bearing legs are supported at 6m from the cantilever end of the poured concrete beam, and the mold bed is supported by the main frame.

[0033] Preferably, the method further comprises the following steps:

[0034] Before pouring the concrete in the joint area, the mold bed is slightly lifted by the vertical cylinder of the rear load-bearing legs;

[0035] The formwork without the frame is locked to the end of the old concrete beam, and then the last area of ​​concrete is poured.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The mobile formwork and construction method for large-span and large-slope beam bridges proposed in the present invention have achieved breakthroughs in difficult problems such as horizontal force transmission of the formwork, precise adjustment of pre-arch, and control of construction joint misalignment by adopting targeted structural improvements and process innovations, and have significantly improved the construction quality and efficiency. The proposed mobile formwork has a reasonable structure, and the various components work together to ensure the stability and load-bearing capacity of the formwork. In particular, the design of the main load-bearing part, the template part, the support and jacking part, etc., fully considers the characteristics of the construction load and the bridge curve, so that the formwork can adapt to the complex construction environment. By optimizing the formwork support system, the misalignment of the construction joint is alleviated, and the overall quality of the bridge is improved. At the same time, the construction method of the mobile formwork also has the characteristics of high efficiency and strong adaptability, which can greatly shorten the construction period and reduce construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the mold frame of the present invention;

[0039] Figure 2 It is a schematic diagram of the front and rear auxiliary legs of the present invention;

[0040] Figure 3 It is a diagram for setting the pre-camber of the mold bed of the present invention;

[0041] Figure 4 It is a technical scheme diagram of the door hanger of the present invention;

[0042] Figure 5 It is a construction process flow chart of the present invention;

[0043] Figure 6 The mold frame of the present invention is suitable for the construction of a beam bridge with a large longitudinal slope Figure 1 ;

[0044] Figure 7 The mold frame of the present invention is suitable for the construction of a beam bridge with a large longitudinal slope Figure 2 ;

[0045] Figure 8 The mold frame of the present invention is suitable for the construction of a beam bridge with a large longitudinal slope Figure 3 ;

[0046] Fig. 9 It is a schematic diagram of the mold closing and casting working condition of the present invention;

[0047] Fig.10 It is a schematic diagram of the mold opening and hole-through working condition of the present invention;

[0048] Fig.11 A technical solution diagram for alleviating construction joint misalignment according to the present invention. DETAILED DESCRIPTION

[0049] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0050] refer to Figure 1 and Figure 2 As shown, a mobile formwork for a large-span and large-slope beam bridge comprises a main truss frame, the main truss frame is connected by high-strength bolts to form a double-main-beam structure, the lower chord frame of the main truss is fixed with a cantilever beam by bolts, the cantilever beam is placed on the top surface of the upper chord of the main truss and is bolted to the lower chord frame;

[0051] The hanging crank arm is hung in the cantilever beam slide mechanism, the slide is connected to the cantilever beam buckle device through a pin shaft, and the crank arm is fixed in position through a limit structure and bolts;

[0052] The outer mold is connected to the bottom hinge seat of the hanging crank arm through a screw rod, the front load-bearing leg is supported on the rod column frame through an ultra-high pressure oil cylinder, and the leg crossbeam trolley slide seat is slidably matched with the longitudinal movement channel of the lower chord of the main truss;

[0053] The column frame is composed of a hoop and a tie rod and is anchored to the bridge pier through precision-rolled threaded steel bars;

[0054] The front auxiliary outrigger is hinged to the front end of the main truss, the bottom is anchored to the front pier support beam through high-strength precision-rolled threaded steel, and the top is connected to the lower chord of the guide beam through a balance hinge;

[0055] The inner mold is connected and fixed to the end mold by bolts, the hydraulic system connects the pump station and the oil cylinder through a high-pressure hose, the electrical system supplies power to the gantry crane through a cable reel, the main power cabinet distributes power through the distribution box, the gantry crane runs on the upper chord track of the main truss, and moves through a half-tire and half-steel wheel mechanism, the electric hoist is connected to the hook through a steel wire rope, the anti-slip device is locked with the main truss longitudinal displacement orifice plate through a pin shaft, and the rod column is rotated and the safety rope is hung when it is reversed.

[0056] The mobile formwork system has significant advantages for the construction of vertical curved and large longitudinal slope beam bridges: the structure is stable and efficient, the main truss frame is used as the core load-bearing structure, and the formwork can be accurately hung in combination with the hanging crank arm. With the jacking cylinder and multi-leg support system, the formwork elevation and slope can be dynamically adjusted to adapt to complex linear shapes; the construction accuracy is improved, the pre-arch adjustment of the bottom mold screw, the hydraulic opening and closing system of the outer mold and the rapid installation process of the inner mold can ensure the quality of box beam forming and reduce manual intervention; the safety performance is outstanding, the high-strength precision-rolled threaded steel anchor, anti-slip device and leg fixing system form multiple protections, the longitudinal movement cylinder and the hydraulic system coordinately control the balance of driving force and friction force to ensure the safety of the formwork through the hole; the construction efficiency is optimized, and auxiliary structures such as small door cranes and rod columns can realize rapid lifting and temporary support of components, and multiple legs are alternately supported in combination with the longitudinal movement mechanism to shorten the time of hole crossing, with a high degree of mechanization; the adaptability is strong, and the front auxiliary leg pier top support beam support and the rear auxiliary leg auxiliary movement can flexibly cope with large longitudinal slope conditions and reduce the investment in temporary facilities. The overall system realizes the intelligence, modularization and safety of complex bridge construction, significantly improving the quality, efficiency and economy of bridge construction, and is particularly suitable for high-intensity and large-slope bridge projects.

[0057] refer to Figure 3 As shown, the movable formwork also includes a formwork part, which includes: a bottom formwork, an outer formwork and an inner formwork. The bottom formwork is used to bear the weight of concrete, and the pre-arch is adjusted by a screw rod. The outer formwork is laterally opened and closed by a mold opening hydraulic cylinder, and the inner formwork is installed before concrete pouring to form the internal space of the box beam. The arching line of the formwork part is based on the characteristics of a quadratic parabola, and the maximum arching value at the mid-span is 250mm, of which the cantilever beam is fixedly arched by 130mm, and the remaining part is adjusted by the movable screw rod of the outer formwork support rod, which effectively reduces the adjustment amount of the outer formwork support rod and is more economical.

[0058] refer to Figure 4 As shown, the running wheel of the small gantry crane adopts a combination of 1 / 2 steel wheel + 1 / 2 rubber tire and is fully driven. Before use, a test platform with a slope of 6% needs to be set up to conduct simulation tests of the small gantry crane running on a large longitudinal slope with no load and heavy load to test its climbing and braking capabilities. The rubber tire has a low hardness and a high friction coefficient. As a driving wheel, it is not easy to slip. The simulation test of the small gantry crane running on a large longitudinal slope with no load and heavy load is carried out on a 6% slope test platform to verify the climbing ability, braking reliability and wheel-rail friction matching of its all-drive steel wheel + rubber tire combination under large longitudinal slope conditions. The test can measure the balance between the power output of the drive system and the slope resistance, test the anti-skid effect of the high friction coefficient design of the rubber tire, expose potential problems such as structural deformation and braking delay under heavy load conditions, ensure the stability and safety of material lifting in actual construction, and avoid the risk of slipping. At the same time, the simulation test provides data support for optimizing running parameters and verifying the compliance of equipment design, ensuring the efficiency and safety of complex linear bridge construction.

[0059] refer to Figure 5 As shown, a construction method for a mobile formwork for a large-span and large-slope beam bridge, used to realize the mobile formwork for the large-span and large-slope beam bridge, comprises the following steps:

[0060] S1, construction preparation stage, the construction preparation stage includes: installing precision rolled threaded steel hangers, installing pier top loose formwork, tying bottom web reinforcement, installing inner formwork, tying top plate reinforcement and installing end formwork;

[0061] S2, concrete pouring and curing stage, the concrete pouring and curing stage includes: pouring concrete and curing;

[0062] S3, the template removal and tensioning stage, the template removal and tensioning stage includes: removing the inner formwork and the end formwork, tensioning the concrete beam body and removing the loose formwork on the pier top;

[0063] S4, the formwork cycle construction process stage, the formwork cycle construction process stage includes: dropping the formwork and removing the hanger, overall mold opening, reversing the legs, longitudinally moving through the hole, adjusting the mold, closing the mold and locking. After locking the template position, enter the next span construction cycle. Through modular process design, efficient connection of the mobile formwork construction of vertical curve and large longitudinal slope beam bridge is achieved: the construction preparation stage integrates the template installation and steel bar binding to ensure the structural preforming accuracy; the concrete pouring and maintenance adopt standardized processes to ensure the quality of the entity; the front and rear load-bearing leg lifting cylinders are used for overall unloading to avoid structural damage; the formwork cycle process innovates the longitudinal movement through the hole and the adjustment and locking process of the mold, combined with the alternating support of multiple legs and the dynamic control of the hydraulic system, to achieve rapid and accurate displacement of the formwork under large longitudinal slope conditions. The whole process significantly shortens the construction period, reduces the risk of high-altitude operations, and improves the bridge line control accuracy and structural durability through process standardization, equipment linkage and linear adaptive design. It is especially suitable for the safe and efficient construction of bridge projects in complex terrain.

[0064] refer to Figure 6 , 7 As shown in , 8, the device for the mobile formwork frame to adapt to the construction of a beam bridge with a large longitudinal slope includes: a mold closing casting state and a mold opening through-hole state;

[0065] refer to Fig. 9 As shown in the figure, the mold-closing pouring state specifically includes: after mold closing, the longitudinal bridge position of the mold bed is adjusted, and the rear end of the bottom mold is connected to the old concrete, the purpose is to fix the rear end of the mold bed to prevent displacement due to the weight of concrete during pouring, and to establish a connection interface between the new and old concrete to ensure that the horizontal force is transmitted through the old beam body; after the bottom mold at the middle pier is supported against the pier pad stone, the bottom molds near the two ends of the middle pier are connected with 32 high-strength fine-rolled threaded steel bars, and the horizontal force is directly transmitted to the pier through rigid contact (bottom mold is tightly pressed against the pad stone) and high-strength steel bar connection, so as to disperse the load during pouring and avoid stress concentration in the middle pier area; finally, the bottom mold at the front end of the cantilever end is connected to the longitudinal displacement channel of the main truss, so that most of the horizontal force during concrete pouring can be transmitted to the already poured bridge-bridge abutment (the already poured beam should be tightly pressed against the end of the bridge abutment), bridge pier and main truss frame, forming an overall force system of "already poured beam-bridge pier-main truss", ensuring that the horizontal force during pouring is jointly borne by the already poured beam, bridge abutment, bridge pier and main truss, and improving the structural stability.

[0066] refer to Fig.10As shown, the mold opening and hole-passing states specifically include: when the mold frame is moving, by adjusting the working pressure of the hydraulic system, the thrust of the longitudinal movement cylinder and the friction force of the mold frame during movement are balanced to avoid excessive horizontal force being transmitted to the bridge structure, prevent damage to the bridge piers or the cast beams, ensure uniform and smooth movement of the mold frame, and reduce inertial impact; an anti-slip device and an anchoring device are set on the legs, and when the longitudinal movement cylinder of the legs reverses the stroke, the anti-slip device is locked with the lower chord of the main truss to prevent the mold frame from slipping due to gravity when moving on a large longitudinal slope, thereby ensuring construction safety; the slope of the mold frame is adjusted by using the long-stroke cylinders of the front and rear auxiliary legs: before the front auxiliary leg reaches the leading pier, the mold frame is adjusted to be parallel to the current span of the bridge; after the front auxiliary leg reaches the leading pier, the elevations of the front and rear auxiliary legs are adjusted to make the mold frame parallel to the next span of the bridge, ensuring that the mold frame is always consistent with the longitudinal slope line of the bridge during the longitudinal movement process, thereby avoiding collision between the template and the bridge or structural stress concentration due to slope deviation.

[0067] In step S2, the concrete pouring condition is as follows: the weight of the concrete is transmitted from: formwork - hanging crank arm - hanger - main truss - load-bearing legs - lifting cylinder, and finally the force is transmitted to the bridge deck and the top of the pier. During pouring, the formwork is closed to form a concrete pouring space and then concrete pouring is carried out. This concrete pouring condition realizes the step-by-step dispersed transmission of loads through a multi-level force transmission system. The main truss frame and the hanging crank arm cooperate to bear the load, ensure the structural stiffness of the closed formwork state, and avoid deformation and displacement during concrete pouring. The force transmission path goes directly to the bridge deck and the top of the pier, and the combined support of the lifting cylinder and the load-bearing legs is used to accurately balance the vertical load and horizontal force under the condition of large longitudinal slope, ensuring the stable closure of the pouring space. The formwork closing process ensures the integrity of concrete forming, reduces the risk of leakage, and cooperates with the hanger system to evenly transmit force to improve the density and linear accuracy of the box girder structure.

[0068] In step S4, the specific conditions for mold dropping and mold opening are as follows: the locking device between the mold bed and the piers and main girders is released, and all vertical constraints of the mold frame are removed. Then, the entire mold bed is lowered by about 200mm under the action of the leg lifting oil jack to complete the mold dropping; after the mold dropping, the 32 high-strength precision-rolled threaded steel bar hanger, the center seam bolts of the hanging curved arm and the connecting bolts of the center seam of the bottom mold are removed, and all lateral constraints on the lateral movement of the mold frame are removed. The mold opening hydraulic cylinder pushes the hanging curved arm and the outer mold plate to open outward by about 4400mm to avoid the lateral space of the pier and complete the mold opening work; the mold dropping and mold opening conditions realize the rapid and safe separation of the mold frame through modular constraint release and hydraulic drive design: the overall mold dropping is 200mm to release the vertical constraints to avoid structural adhesion damage; the high-strength hanger and bolts are removed to remove lateral obstacles and ensure the freedom of lateral movement; the mold opening cylinder accurately pushes the outer mold to move 4400mm horizontally to avoid the space limitation of the pier and adapt to the complex linear shape of the large longitudinal slope. The hydraulic system synchronously controls the lifting and lateral movement to ensure balanced descent of the mold frame and symmetrical mold opening to avoid structural deformation. The mechanized operation of the entire process reduces manual intervention, shortens the mold removal time, and ensures the safety of hole passing. The multi-level constraint release and hydraulic collaborative design not only meet the construction requirements of rapid detachment of the mold frame under large longitudinal slope conditions, but also ensure the stability of the mold opening process through static structure force transmission, providing a reliable premise for the longitudinal movement of the mold frame through the hole, and significantly improving the efficiency and safety of the cycle construction.

[0069] The leg-reversing working condition includes: the reversal of the rear load-bearing leg and the first reversal of the front load-bearing leg and the rod column, among which, the reversal of the rear load-bearing leg is specifically as follows: after the mold frame is opened, the mold frame is lifted 200mm to restore to the elevation of 4200mm, and is supported by the rear auxiliary leg and the front load-bearing leg. The rear load-bearing leg is reversed by the longitudinal shift cylinder of the rear load-bearing leg to the front end of the poured concrete beam about 6m away from the center line of the front load-bearing leg for installation; among which, the first reversal of the front load-bearing leg and the rod column is specifically as follows: after the rear load-bearing leg is reversed into place and installed, it is supported by the rear auxiliary leg and the rear load-bearing leg, and the front load-bearing leg and the rod column are reversed by the longitudinal shift cylinder of the front load-bearing leg to the position of 6m from the cantilever end of the poured concrete beam, and supported on the surface of the poured concrete beam by the upper frame beam of the rod column and anchored; the leg-reversing working condition significantly improves construction efficiency and safety through staged load-bearing and precise positioning. The formwork is lifted to restore the elevation to ensure structural stability, and the longitudinal cylinder is used to autonomously move the outriggers to achieve millimeter-level precision positioning, reducing manual adjustment time. The mechanical transfer mode of alternating loads of the front and rear outriggers effectively disperses the load and avoids the risk of local overload of the concrete beam. The use of precast beams as fulcrums and anchoring not only strengthens the integrity of the support system and the existing structure, but also ensures the safety of cantilever operations. This process optimizes the connection of processes through mechanized operations and shortens the equipment turnover cycle. It is particularly suitable for the standardized construction of continuous beam sections, while reducing the risk of high-altitude operations and ensuring that the construction quality and progress are controlled simultaneously.

[0070] The specific working conditions of longitudinal movement through the hole are as follows: after the formwork legs are reversed, the longitudinal movement cylinders of the front and rear load-bearing legs are used to push the formwork forward 9.55m; the front auxiliary legs are lifted and supported on the anchored front pier support beam, the front load-bearing leg lifting cylinders are retracted, and the front load-bearing legs and rods are reversed to the top of the front pier for installation and anchoring using the longitudinal movement cylinders of the front load-bearing legs themselves. A small gantry crane is required to lift the middle small rods and the bottom beam of the large rods to the front pier in advance for installation and anchoring; the front auxiliary legs are retracted and the front support is retracted. The formwork is moved forward 8m by using the longitudinal cylinders of the front and rear load-bearing legs; the lifting cylinders of the rear auxiliary legs are retracted, and the formwork continues to move longitudinally 42.45m to the standard casting position of the lower span, thus completing the forward movement of the mobile formwork through the hole; finally, the rear auxiliary legs and the rear load-bearing legs are transported in sequence to the support position of the next span; the front auxiliary legs and the pier support beam form a temporary rigid support, and the process of pre-installing the rod column with the small gantry crane is pre-placed, which greatly shortens the leg transportation and anchoring time. The mechanical balance strategy of alternating lifting and retracting of multiple legs effectively disperses the local pressure of the formwork load on the pier body and beam body. The full-process mechanized operation reduces high-altitude manual work, and the automatic positioning system is combined to ensure the accuracy of cross-pier displacement, especially suitable for the construction of curved sections or variable-span bridges, which significantly improves the construction safety and continuity under complex working conditions.

[0071] The specific working conditions of mold closing and mold adjustment are as follows: the mold opening hydraulic cylinder pushes the hanging crank arm to close inward, driving the outer template to close inward, and after closing, the connecting bolts of the center seam of the bottom mold, the center seam bolts of the hanging crank arm and the precision-rolled threaded hanger are connected. Finally, the entire mold bed is lifted into place under the action of the leg lifting cylinder, and the mold bed elevation and center line are adjusted to put the entire mold frame into the pouring state. The mold closing and mold adjustment working conditions significantly improve the construction accuracy and efficiency through hydraulic drive and mechanical interlocking. The hydraulic cylinder pushes the hanging crank arm to synchronously close the outer mold to ensure that the template joints are tight and there is no misalignment, reducing the risk of leakage in the later stage. The center seam of the bottom mold and the center seam of the crank arm are connected by bolts, supplemented by precision-rolled threaded hangers to form a rigid whole, enhancing the deformation resistance of the mold frame. The lifting cylinder accurately adjusts the elevation and center line of the mold bed to eliminate the structural deviation before pouring and ensure that the beam line shape is completely matched with the design parameters. Mechanized operation of the entire process reduces manual intervention, and modular assembly significantly shortens the time between process connections. At the same time, the closed-loop control of the hydraulic system effectively avoids overload hazards, ensuring that the quality of concrete molding and construction safety are optimized simultaneously.

[0072] refer to Fig.11 As shown in the figure, for continuous bridges, the segmentation point is about 1 / 5 to 1 / 4 of the next span. When constructing the rear span, there is a problem of butt joint between the new and old concrete, and the elastic formwork supported by the main frame has a large deflection (28.6mm) at the segmentation point (if no support is added to alleviate the misalignment). In order to alleviate the misalignment, the rear load-bearing legs stand 6m from the cantilever end of the poured beam to support the main frame. In addition to this method, the following methods are also used to alleviate the misalignment:

[0073] 1. Before pouring the concrete in the joint area, that is, at the position marked ④ in the figure, push the rear load-bearing legs vertically up the cylinder slightly;

[0074] 2. Lock the formwork (without the frame) with the end of the old concrete beam. Pour the concrete in the last area.

[0075] The above measures can further alleviate the misalignment of construction joints and make the bridge line more beautiful.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A mobile formwork for a large-span and large-slope beam bridge, characterized in that: It includes a main truss frame, the main truss frame is connected by high-strength bolts to form a double main beam structure, the main truss lower chord frame is fixed with a cantilever beam by bolts, the cantilever beam is placed on the top surface of the main truss upper chord rod and is bolted to the lower chord frame; The hanging crank arm is hung in the cantilever beam slide mechanism, the slide is connected to the cantilever beam buckle device through a pin shaft, and the crank arm is fixed in position through a limit structure and bolts; The outer mold is connected to the bottom hinge seat of the hanging crank arm through a screw rod, the front load-bearing leg is supported on the rod column frame through an ultra-high pressure oil cylinder, and the leg crossbeam trolley slide seat is slidably matched with the longitudinal movement channel of the lower chord of the main truss; The column frame is composed of a hoop and a tie rod and is anchored to the bridge pier through precision-rolled threaded steel bars; The front auxiliary outrigger is hinged to the front end of the main truss, the bottom is anchored to the front pier support beam through high-strength precision-rolled threaded steel, and the top is connected to the lower chord of the guide beam through a balance hinge; The inner mold is connected and fixed to the end mold by bolts, the hydraulic system connects the pump station and the oil cylinder through a high-pressure hose, the electrical system supplies power to the gantry crane through a cable reel, the main power cabinet distributes power through the distribution box, the gantry crane runs on the upper chord track of the main truss, and moves through a half-tire and half-steel wheel mechanism, the electric hoist is connected to the hook through a steel wire rope, the anti-slip device is locked with the main truss longitudinal displacement orifice plate through a pin shaft, and the rod column is rotated and the safety rope is hung when it is reversed.

2. The mobile formwork for a large-span and large-slope beam bridge according to claim 1, characterized in that: It also includes the formwork part. The arch line of the formwork part is based on the characteristics of a quadratic parabola. The mid-span arch range is 33-250mm, of which the fixed arch range of the cantilever beam is 16-130mm, and the remaining part is adjusted by the movable screw rod of the outer formwork support rod.

3. The mobile formwork for a large-span and large-slope beam bridge according to claim 1, characterized in that: The running wheels of the small gantry crane adopt a combination of 1 / 2 steel wheel + 1 / 2 rubber tire and are all-wheel drive. Before use, a test platform with a slope of 6% needs to be set up to carry out a simulation test of the small gantry crane running on a large longitudinal slope with no load and with a heavy load to check its climbing and braking capabilities.

4. A construction method for a mobile formwork for a large-span and large-slope beam bridge, characterized in that: The method for realizing a mobile formwork for a large-span and large-slope beam bridge as claimed in any one of claims 1 to 3 comprises the following steps: S1, construction preparation stage, the construction preparation stage includes: installing precision rolled threaded steel hangers, installing pier top loose formwork, tying bottom web reinforcement, installing inner formwork, tying top plate reinforcement and installing end formwork; S2, concrete pouring and curing stage, the concrete pouring and curing stage includes: pouring concrete and curing; S3, the template removal and tensioning stage, the template removal and tensioning stage includes: removing the inner formwork and the end formwork, tensioning the concrete beam body and removing the loose formwork on the pier top; S4, the mobile formwork cycle construction process stage, the mobile formwork cycle construction process stage includes: dropping the formwork and removing the hanger, overall mold opening, reversing the legs, longitudinally moving through the hole, adjusting the formwork, closing the formwork and locking. After locking the formwork position, enter the next span construction cycle.

5. The construction method of a mobile formwork for a large-span and large-slope beam bridge according to claim 4, characterized in that: The specific steps of the movable mold frame in the mold closing casting state are: After closing the mold, connect the rear end of the bottom mold to the old concrete; After the bottom formwork at the middle pier is supported against the pier pad stone, the bottom formwork at both ends of the middle pier is connected with threaded steel bars; Finally, the bottom formwork at the front end of the cantilever end is connected to the longitudinal displacement channel of the main truss.

6. A construction method for a mobile formwork for a large-span and large-slope beam bridge according to claim 4, characterized in that: The movable mold frame in the mold opening and hole-passing state specifically includes: When the mold frame is moving, adjust the working pressure of the hydraulic system to balance the thrust of the longitudinal cylinder and the friction force when the mold frame moves; An anti-slip device and an anchoring device are installed on the outriggers. When the outrigger longitudinal movement cylinders are reversed, the anti-slip device is locked with the lower chord of the main truss. Use the long-stroke cylinders of the front and rear auxiliary legs to adjust the slope of the formwork: before the front auxiliary legs reach the advance pier, adjust the formwork to be parallel to the current span; after the front auxiliary legs reach the advance pier, adjust the elevations of the front and rear auxiliary legs to make the formwork parallel to the next span.

7. The construction method of a mobile formwork for a large-span and large-slope beam bridge according to claim 4, characterized in that: In step S2, the concrete pouring condition is as follows: the weight of the concrete is transmitted from: formwork - hanging crank arm - hanger - main truss - load-bearing support leg - lifting cylinder, and finally to the bridge deck and the top of the pier. During pouring, the formwork is closed to form a concrete pouring space and then concrete pouring is carried out.

8. The construction method of a mobile formwork for a large-span and large-slope beam bridge according to claim 4, characterized in that: In step S4, the specific working conditions of mold dropping and mold opening are as follows: release the locking device between the mold bed and the bridge pier and main truss, remove the vertical constraint of the mold frame, and complete the mold dropping; after the mold dropping, remove the threaded steel bar hanger rod, the center seam bolt of the hanging crank arm and the connecting bolt of the center seam of the bottom mold, remove the lateral constraint of the mold frame, and complete the mold opening work; The leg-reversing working conditions include: the rear load-bearing leg reverse transportation: after the formwork is opened and jacked up, it is supported by the rear auxiliary legs and the front load-bearing legs, and the rear load-bearing legs are reversed to the front end of the poured concrete beam for installation through the longitudinal cylinder; the front load-bearing legs and rod columns are reversed for the first time: after the installation of the rear load-bearing legs is completed, they are supported by the rear auxiliary legs and the rear load-bearing legs, and the front load-bearing legs and rod columns are reversed to the designated position of the cantilever end of the poured beam through the longitudinal cylinder, and anchored to the beam surface using the rod column frame beam support; The specific working conditions of longitudinal movement through the hole are as follows: after the formwork is inverted, it is pushed forward by the longitudinal movement cylinders of the front and rear load-bearing legs; the front auxiliary legs are lifted to support the front pier support beam, and the front load-bearing legs and rods are transported backward to the front pier for installation and anchoring; the formwork is moved forward again, and after the rear auxiliary legs are folded, it continues to be longitudinally moved to the standard casting position of the lower span; finally, the rear auxiliary legs and the rear load-bearing legs are transported backward to the support position of the next span; The specific working conditions of mold closing and mold adjustment are as follows: push the hanging crank arm and the outer mold plate inward through the mold opening hydraulic cylinder; complete the connection of the center seam of the bottom mold, the center seam bolts of the hanging crank arm and the precision-rolled threaded hanger rod; use the outrigger lifting cylinder to lift the mold bed as a whole, and adjust the mold bed elevation and center line to the casting state.

9. The construction method of a mobile formwork for a large-span and large-slope beam bridge according to claim 4, characterized in that: To alleviate the misalignment of the construction joint, in the steps, the rear load-bearing legs are supported at 6m from the cantilever end of the poured concrete beam, and the mold bed is supported by the main frame.

10. A construction method for a mobile formwork for a large-span and large-slope beam bridge according to claim 9, characterized in that: The following steps are also included: Before pouring the concrete in the joint area, the mold bed is slightly lifted by the vertical cylinder of the rear load-bearing legs; The formwork without the frame is locked to the end of the old concrete beam, and then the last area of ​​concrete is poured.

Images