Pier column construction method for bridge construction

Abstract

The invention relates to the technical field of bridge construction, in particular to a pier column construction method for bridge construction, which is characterized in that a small platform at the lower part and a manual channel between the upper platform and the lower platform are added on the basis of a conventional turnover formwork, and the small platform and the manual channel are used for formwork installation; the steel reinforcement framework is composed of four layers of vertically-through steel reinforcement operation platforms and is mainly used for steel reinforcement binding. Compared with a conventional rollover system, the novel rapid rollover system is additionally provided with the reinforcement cage platform for binding the reinforcement and the manual channel, and has the following advantages that site constructors can bind a reinforcement cage with the height of 8 m in the octagonal cage at a time, and compared with a traditional construction scheme of binding a reinforcement cage with the height of 2 m at a time, the construction efficiency is improved, and the construction cost is reduced. In addition, the safety of construction operation in the closed steel reinforcement framework is higher, the labor input is reduced, and the construction cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and specifically provides a construction method for bridge piers in bridge construction. Background Art

[0002] Bridge high pier construction plans include support construction and non-support construction, which specifically depend on various factors such as on-site site conditions, construction costs, progress, and risk control. Generally speaking, the higher the pier, the narrower the site, and the worse the foundation support conditions, the more advantages the non-support plan has in comparison.

[0003] Currently, bridge pier construction mainly adopts traditional construction methods, including steps such as steel bar binding, formwork installation, and concrete pouring. However, these methods have problems such as low construction efficiency, large manual input, and high safety risks, especially in large bridge projects, these problems are particularly prominent. Summary of the Invention

[0004] 1. Technical Problems to be Solved The present invention aims to solve the problems existing in the current bridge pier construction, such as low efficiency, large manual input, and high safety risks, and provides an efficient, safe, and reliable construction method.

[0005] (II) Technical Solutions Based on this, the present invention provides the following technical solution: a construction method for bridge piers in bridge construction, and the specific construction method steps are as follows: Step S1: Steel bar processing and installation. The steel bars are made into a steel bar framework in the processing yard, and a protective layer is additionally provided on the outside of the steel bars. A crane is used to lift and lap-join with the pile foundation steel bars. The steel bar framework is welded by 75-angle steel into a regular octagon with a height of 7.5 m. The operation platform consists of an inner octagon and an outer octagon. A 3-mm-thick and 800-mm-wide patterned steel plate is welded between the inner ring and the outer ring as a steel bar binding catwalk, which is set every 2 m. When binding the first form of steel bars, they are placed on the ground, and the rest are placed on the large platform of the form turnover. Four 12# steel wire ropes are used as guy ropes to ensure the stability of the steel bar framework. A climbing ladder is set in the inner ring or outer ring, and a manhole is set between the rings to facilitate workers to operate up and down; Step S2: Erection of the safety ladder cage. The access passage for construction personnel uses a safety ladder cage, and the height of the ladder cage can reach 110 m. A connecting passage is set at the platform of the first form of the form turnover (i.e., the last form lifted last time). The specific steps are as follows: The base is placed on the horizontal ground and firmly connected by bolts; The first-floor platform is installed on the base, and after adjusting the level, it is tightened with high-strength bolts; The vertical poles are respectively installed on the connecting sleeves of the platform with high-strength bolts; The bottom platform is placed on the tops of the four vertical poles; The stairs are installed between the upper and lower platforms; The handrails are installed inside the stairs; The side protective nets are installed; The access safety doors are installed; The vertical poles, platforms, stairs, and protective nets of the upper level are installed until the working height; Step S3: Pier column formwork installation. The pier shaft is constructed using prefabricated steel assembled formwork. The formwork is fabricated and assembled in sections according to the dimensions. Each set of formwork is uniformly numbered to prevent confusion. The formwork is processed by a professional steel structure construction team and designed as large steel formwork according to the lifting capacity to ensure a smooth concrete surface. The cylindrical pier shaft formwork is made into two semi-circular steel forms, with a formwork installation operation platform attached to the top of the steel form. The sectional length is 2m, and 10 semi-circular steel forms are made for each pier column diameter for easy turnover and form flipping. The formwork at the tie beam is designed separately, with a flat area set at the end of the semi-circle. The formwork at the top of each section is connected by flange plates and high-strength bolts and tightened with double nuts. Each joint seam is no more than 2mm, with leak-proof rubber strips set and plastered with putty; Step S4: Concrete pouring. The concrete pouring adopts the horizontal layered continuous pouring method, with the layered thickness controlled within 30cm to ensure uniform concrete placement and prevent formwork displacement. The vibration is carried out using internal vibrators, and the moving distance of the vibrator rods does not exceed 1.5 times the action radius of the vibrator to ensure dense concrete vibration; Step S5: Formwork flipping. The formwork flipping adopts a 5-section formwork system, with each section of the formwork being 2m high. Each time, 4 forms (a total of 8m) are flipped. When the concrete strength of the pier shaft is greater than 10MPa, the formwork removal is started for flipping. The flipping is carried out in the order of the bottom section first, then the middle section, and finally the top section. When removing the formwork, the operator enters the lower platform of the lowest formwork through the manual passage between the upper and lower platforms, removes the connecting bolts of the lower formwork, and then enters the lower platform of the upper formwork through the manual passage. Since the construction platforms of the two layers of formwork are independent, when the lower formwork is flipped by the tower crane in this way, it will not affect the safety of the operators on the upper formwork. Repeat the formwork removal and flipping steps of the lowest formwork to complete the removal and flipping of the upper 3 layers of formwork in turn, and only one layer of formwork is retained as the support for the upper construction platform; Step S6: Pier shaft curing. Sprinkler curing starts after the concrete has finally set. According to the season and weather conditions, measures such as covering with tarpaulins, steam curing, or covering with geotextiles and sprinkling water are taken to keep the surface of the structure moist. The pier shaft curing is divided into two layers: the bottom layer is wrapped with geotextiles, and the outer layer is wrapped with plastic film and a leakage bucket is placed on the top of the pier shaft to keep the humidity of the pier shaft. The sprinkler moisturizing curing time is not less than 7d. When the pier shaft is relatively high, the system errors of wind force and steel ruler need to be considered, and the method of total station trigonometric leveling can be used to control the elevation of the pier shaft formwork.

[0006] Preferably, the specific processing steps of the lifting in Step S1 described above are as follows: The longitudinal reinforcement of the pier column is hoisted using a steel bar lifting cage. The main hook of the crane hooks the steel bar lifting cage and slowly lifts it to place it at the center position of the pier column. The operator lap-joints and extends the pile foundation steel bars. After the binding is completed, the steel bar cage is lifted away by the crane to prepare for the next step.

[0007] (III) Beneficial effects Compared with the prior art, the present invention provides a pier construction method for bridge construction, which has the following beneficial effects: This pier construction method for bridge construction is based on the conventional formwork turnover formwork, and a small platform at the lower part and a manway between the upper and lower platforms are added. The small platform and the manway are used for formwork installation; the steel bar framework is composed of 4 layers of steel bar working platforms that penetrate up and down, mainly used for steel bar binding. Compared with the conventional formwork turnover system, the new type of fast formwork turnover system adds a steel bar framework platform and a manway for binding steel bars, and has the following advantages: On-site construction personnel can bind a steel bar framework with a height of 8 m at one time in the octagonal cage. Compared with the traditional construction plan of binding a steel bar framework with a height of 2 m at one time, not only the construction efficiency is improved, but also the construction safety in the enclosed steel bar framework is higher, the manual input is reduced, and the construction cost is lowered; In on-site construction, 4 segments of concrete with a height of 8 m can be poured at one time, while the traditional formwork turnover construction can only pour about 4 m of concrete at one time, which improves the construction efficiency of concrete and reduces the working joints of concrete; The disassembly and assembly of the connecting bolts of the formwork turnover formwork are all completed in the upper and lower platforms and the enclosed manway, which increases the safety of high-altitude operations. Description of the Drawings Figure 1 It is the flow chart of the construction method of the present invention; Figure 2 It is the structural diagram of the steel bar framework of the present invention; Figure 3 It is the schematic diagram of formwork installation and concrete pouring of the present invention. Detailed Embodiment

[0008] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0009] Embodiment 1 Taking the construction of the highest pier height of nearly 49 m of the widened bridge and the turning ramp bridge of Taohuaxi Bridge as an example, the method of the present invention is used for construction. Please refer to Figures 1 - 3 , and the specific construction method steps are as follows: Steel bar processing and installation: The steel bars are fabricated into a steel bar framework in the processing yard, and a protective layer is additionally provided on the outside of the steel bars. A crane is used for hoisting and lapping and extending the steel bars with the pile foundation steel bars. The steel bar framework is welded by 75-angle steel into a regular octagon with a height of 7.5 m. The operation platform consists of an inner octagon and an outer octagon. A pattern steel plate with a thickness of 3 mm and a width of 800 mm is welded between the inner ring and the outer ring as a steel bar binding catwalk, which is arranged every 2 m. When binding the first form of steel bars, they are placed on the ground, and the rest are placed on the large platform of the form turnover. Four 12# steel wire ropes are used as guy ropes to ensure the stability of the steel bar framework. When binding the steel bars, it is carried out strictly in accordance with the design requirements to ensure that the main steel bars are vertical and in accurate positions, and the joints of the main steel bars are staggered from each other. A ladder is installed on the inner ring or the outer ring, and a manhole is arranged between the rings to facilitate the workers to operate up and down. The longitudinal steel bars of the pier column are hoisted by a steel bar hoisting cage. The main hook of the crane hooks the steel bar hoisting cage and slowly lifts it to place it at the center position of the pier column. The operating workers lap and extend the pile foundation steel bars. After the binding is completed, the steel bar framework is lifted by the crane and removed to prepare for the next step of work; In this application, 75-angle steel is a kind of angle steel material with specific specification dimensions. Its specification dimensions usually refer to the cross-sectional dimensions of the angle steel, that is, the width and thickness of the angle steel. Specifically, the specification dimensions of 75-angle steel are generally 75*75 mm, and the thickness is 5 - 12 mm. Because of its appropriate specification dimensions, this kind of angle steel can be applied to various uses, such as the support, processing and welding of building structures, etc. When purchasing 75-angle steel, in addition to paying attention to the selection of specification dimensions and materials, factors such as its bearing capacity, processing performance and price should also be considered. The wide pattern steel plate refers to a steel plate with patterns on the surface and a relatively large width. The patterns of this kind of steel plate are usually in the shape of lentils, diamonds, round beans or a mixture of flat circles, mainly playing the roles of anti-slip and decoration; The guy rope, also known as the drag rope or cable, is a kind of rope that plays a role in balancing and fixing. In mast hoisting and various high-rise structures, the guy rope is an important stability system, used to keep the mast upright and stable, and bear part of the load in the mast hoisting. Its existence is directly related to the safe operation of the mast crane. Installation of the safety ladder cage: The access passage for construction personnel adopts a safety ladder cage, and the height of the ladder cage can reach 110 m. A connecting passage is set at the platform of the first form of the form turnover (that is, the last form lifted last time) of the ladder cage. The specific steps are as follows: The base is placed on the horizontal ground and firmly connected by bolts; The first-floor platform is installed on the base, and after adjusting the level, it is tightened with high-strength bolts; The vertical poles are respectively installed on the connecting sleeves of the platform with high-strength bolts; The bottom platform is placed on the tops of the four vertical poles; The stairs are installed between the upper and lower platforms; The handrails are installed on the inner side of the stairs; The side protection nets are installed; The access safety doors are installed; The vertical poles, platforms, stairs and protection nets of the upper level are installed until the working height; In this application, high-strength bolts are made of high-strength steel or bolts that require a relatively large pre-tightening force. The core difference between high-strength bolts and ordinary bolts does not lie in the strength of the materials used, but in the form of force. The essence of high-strength bolts is to apply pre-tightening force and use static friction to resist shear force. Therefore, high-strength bolts are also known as High-Strength Friction Grip Bolts, abbreviated as HSFG in English. For the installation of pier column formwork, the pier body is constructed using prefabricated steel formwork processed according to specifications. The formwork is fabricated and assembled in sections according to dimensions, and each set of formwork is uniformly numbered, as Figure 3 shown to prevent confusion. The formwork is processed by a professional steel structure construction team and designed as large steel formwork according to the lifting capacity to ensure a smooth concrete surface. The formwork for the cylindrical pier body is made into two semi-circular steel molds, with a formwork installation operation platform attached to the top of the steel molds. The sectional length is 2m, and 10 semi-circular steel molds are fabricated for each pier column diameter for easy turnover and form flipping. The formwork at the crossbeam is designed separately, with a flat area set at the end of the semi-circle. The formwork at the top of each section is connected by flange plates and high-strength bolts and tightened with double nuts. Each joint seam is not more than 2mm, and anti-leakage rubber strips are set and plastered with putty. Before formwork installation, trial assembly is carried out to check the stiffness, joint tightness, and structural dimensions of the formwork. During formwork installation, a total station is used to track and align the center line position and verticality to ensure that the relative position between the formwork and the steel bar cage meets the design requirements; For concrete pouring, the concrete is uniformly mixed at the mixing station and transported to the site by concrete mixer trucks. Before concrete pouring, check whether the formwork support is firm, whether the formwork joints leak, whether the steel bar spacing and position are accurate, etc. The concrete pouring adopts the horizontal layered continuous pouring method, with the layered thickness controlled within 30cm to ensure uniform concrete placement and prevent formwork displacement. The vibration is carried out using internal vibrators, and the moving distance of the vibrator rods does not exceed 1.5 times the action radius of the vibrator. It is necessary to vibrate the concrete thoroughly until the air bubbles no longer emerge, and the surface is flat and slurry oozes out. After pouring, the exposed concrete surface should be promptly repaired and leveled, and then plastered a second time and troweled smooth after the slurry has set; Form jacking: The form jacking adopts a 5-section formwork system. The height of each section of formwork is 2m, and each time 4 forms (a total of 8m) are jacked up. When the concrete strength of the pier body is greater than 10MPa, the formwork removal is started for form jacking. The form jacking is carried out in the order of the bottom section first, then the middle section, and finally the top section. When removing the formwork, the operator enters the lower platform of the lowest formwork through the manual passage between the upper and lower platforms, removes the connecting bolts of the lower formwork, and then enters the lower platform of the upper formwork through the manual passage. Since the construction platforms of the two layers of formwork are independent, when the lower formwork is jacked up by the tower crane in this way, it will not affect the safety of the operators on the upper formwork. Repeat the removal and jacking steps of the lowest formwork to complete the removal and jacking of the upper 3 layers of formwork in turn, and only one layer of formwork is retained as the support for the upper construction platform; Pier body maintenance: Sprinkling maintenance starts after the concrete has finally set. According to the season and weather conditions, measures such as wrapping with tarpaulins, steam curing, or covering with geotextiles and sprinkling water are taken to keep the surface of the structure moist. The pier body maintenance is divided into two layers: the bottom layer is wrapped with geotextiles, and the outer layer is wrapped with plastic film and a leaking bucket is placed on the top of the pier body to keep the humidity of the pier body. The sprinkling and moisture-keeping maintenance time is not less than 7d. When the pier body is relatively high, the system errors of wind force and steel tape need to be considered, and the method of total station trigonometric leveling can be used to control the elevation of the pier formwork.

[0010] All high-pier constructions have been completed using the pier column construction method for bridge construction proposed in this paper. Compared with the traditional formwork turnover construction and full hall scaffolding construction, the fully enclosed formwork turnover replaces the traditional formwork turnover, greatly saving the material cost and labor cost of erecting the scaffolding, comprehensively reducing the project construction measure cost by 730,000 yuan, and saving the construction period by 150d; Using the developed and designed fully enclosed formwork turnover improves the working efficiency of workers at high altitudes, saves 330,000 yuan in labor costs, and saves the construction period by 21d. Using the developed and designed fully enclosed formwork turnover, when connecting the bridge pier steel bars, there is no need to consider cutting the main bars due to the primary installation height, wasting materials and adding sleeves. It comprehensively saves 160,000 yuan in material costs and labor costs, and saves the construction period by 19d. Applying BIM technology to establish a three-dimensional model, optimizing the connection nodes of the designed components, and forming a detailed design drawing to provide technical support for the fabrication and installation of the components; Applying BIM technology can accurately determine the center of gravity of the octagonal cage, select the correct lifting points, prevent eccentric instability during the lifting process, and improve the operation safety factor. Applying BIM technology can avoid unnecessary rework while ensuring the accuracy of actual operations, improving work efficiency. This technology comprehensively saves 40,000 yuan in costs and advances the construction period by 3d; Reduces the machinery required for form removal and saves 2.7 million yuan in crane costs. The application of this construction method in the transformation project from Wutai Mountain Interchange to Shuangshan Tunnel section and the reconstruction and expansion project of G352 Wuchuan Daojiao to Outang Highway realizes the optimization of the long-section formwork turnover for one-time pouring of bridge high piers, reducing the cost by about 1.53 million yuan in total and advancing the construction period by 193d.

[0011] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a pier for bridge construction, characterized in that: The specific construction method steps are as follows: Step S1: steel bar processing and installation, the steel bar is made into a steel bar skeleton in the processing yard, and a protective layer is added on the outside of the steel bar, and the steel bar is hoisted by a crane and overlapped with the pile foundation steel bar for extension; Step S2: Setting up the safety cage; Step S3: The pier column formwork is installed, and the pier body is constructed using a prefabricated steel formwork; Step S4: concrete pouring, the concrete pouring adopts the horizontal layered continuous pouring method, and the layer thickness is controlled within 30cm to ensure uniform concrete feeding and prevent template displacement; Step S5: turning the template up; Step S6: Pier body curing: after the concrete has finally set, watering curing begins. Depending on the season and weather conditions, measures such as tarpaulin wrapping, steam curing, or geotextile covering and watering curing are taken to keep the surface of the structure moist.

2. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As mentioned above, the specific processing steps of the steel skeleton in step S1 are as follows: the steel skeleton is welded from 75 angle steel into a 7.5m high regular octagon, the operating platform is composed of an inner octagon and an outer octagon, and a 3mm thick, 800mm wide patterned steel plate is welded between the inner ring and the outer ring as a steel bar binding horseway, one is set every 2m, the first mold steel bars are placed on the ground when they are tied, and the rest are placed on the large mold turning platform, and four 12# steel wire ropes are used as cable wind ropes to ensure the stability of the steel skeleton.

3. A method for constructing a pier for bridge construction according to claim 2, characterized in that: Ladders are provided in the inner or outer ring and manholes are provided between the rings.

4. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As mentioned above, the specific processing steps of lifting in step S1 are as follows: the longitudinal reinforcement of the pier column is hoisted by a reinforcement hoisting cage, the main hook of the crane hooks the reinforcement hoisting cage, slowly lifts it and places it in the center of the pier column, the operator overlaps and lengthens the pile foundation reinforcement, and after the binding is completed, the reinforcement skeleton is lifted away by the crane to prepare for the next step of work.

5. The method for constructing a pier for bridge construction according to claim 1, characterized in that: The specific steps of setting up the safety ladder cage in step S2 as described above are: placing the base on a horizontal ground and firmly connecting it with bolts; The first-floor platform is installed on the base, and after adjusting the level, it is tightened with high-strength bolts; Install the vertical poles on the connecting sleeves of the platform with high-strength bolts respectively; Place the bottom platform on top of the four poles; Install stairs between upper and lower landings; The handrail is installed on the inside of the stairs; Install side protection nets; Install entry and exit security doors; Install the next level of poles, platforms, stairs, and protective nets up to the working height.

6. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As described above, the specific operation steps for installing the pier column formwork in step S3 are as follows: the cylindrical pier body formwork is made into two semicircular steel formworks, and a formwork installation operation platform is attached to the top of the steel formwork. The section length is 2m, and 10 semicircular steel formworks are made for each pier column diameter. A flat plate area is set at the end of the semicircle. The top of each section of the formwork is connected with a flange and high-strength bolts and tightened with double nuts. Each joint is no larger than 2mm, and a leak-proof tape is set, and it is smoothed with putty.

7. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As described above, in step S4, the vibrator used in the concrete pouring is an inserted vibrator, and the moving distance of the vibrator rod does not exceed 1.5 times the action radius of the vibrator.

8. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As described above, the specific operation of template lifting in step S5 is as follows: the template is lifted using a 5-section template system, each section of the template is 2m high, and 4 templates are lifted each time. When the concrete strength of the pier body is greater than 10MPa, the template is removed and prepared for lifting. The lifting is carried out in the order of bottom segment first, middle segment, and top segment last. The operator enters the lower platform of the lowest template from the artificial passage between the upper and lower platforms, removes the connecting bolts of the lower template, and then enters the lower platform of the upper template through the artificial passage, repeats the removal and lifting steps of the lowest template, and completes the removal and lifting of the upper 3 layers of templates in turn, leaving only one layer of template as the support of the upper construction platform.

9. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As described above, the pier body maintenance in step S6 is divided into two layers: the bottom layer is wrapped with geotextile, the outer layer is wrapped with plastic film and a leak bucket is placed on the top of the pier body to maintain the humidity of the pier body, and water is sprinkled to keep it moist for no less than 7 days.

10. A method for constructing a pier for bridge construction according to claim 1, characterized in that: As described above, in step S6, the elevation of the pier body formwork can be controlled by using the total station trigonometric elevation method.

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