Turnover and sliding integrated construction method for hollow thin-wall pier

Abstract

The invention discloses a hollow thin-wall pier turning and sliding integrated construction method, and particularly relates to the field of bridge engineering, the method comprises the following steps: 1, construction preparation: chiseling and cleaning a bearing platform before lofting, and releasing a pier body plane position on the bearing platform; 2, steel bars are manufactured and installed. According to the method, the high pier inner sliding and outer turning construction is not simply combined by adopting two processes of sliding formwork construction and turning formwork construction, but sliding and turning integrated construction is achieved through improvement on the basis of a sliding formwork system, the advantages of the two processes of sliding formwork construction and turning formwork construction are integrated, and the defects of sliding formwork construction and turning formwork construction are overcome. According to the basic principle, a slip form system is utilized, the distance between an outer side formwork of a hollow pier body and an enclosure of the slip form system is set to be 40 cm, the outer side formwork is supported on the enclosure through an adjusting lead screw, the outer side formwork is vertically hung on a bracket through a hanging ring, and mounting and dismounting of the formwork are achieved through the adjusting lead screw. In order to prevent formwork deformation during concrete pouring, the inner formwork is supported by an integral truss, and the outer formwork is additionally provided with an opposite-pull screw for auxiliary reinforcement.

Description

Technical Field

[0001] The present invention relates to the field of bridge engineering, and more specifically, to a hollow thin-wall pier flip-slide integrated construction method. Background Art

[0002] Since the 1970s, with the development of new technologies such as sliding steel formwork, prefabricated components and prestressed assembly, the difficulties in construction such as on-site formwork, high-altitude operations, slow construction, poor quality, and labor and material costs have been overcome, and thin-walled hollow bridge piers have been increasingly widely used. The construction methods of hollow thin-walled piers that have been built or are under construction in China mainly include sliding formwork, climbing formwork, and flip formwork, but each method has its own advantages and disadvantages. Summary of the invention

[0003] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a method for the sliding and flipping integrated construction of a hollow thin-walled pier. The method for the inward sliding and outward flipping construction of a high pier does not simply adopt a combination of the two processes of sliding formwork construction and flipping formwork construction, but realizes the sliding and flipping integrated construction through improvements on the basis of the sliding formwork system, which combines the advantages of the two processes of sliding formwork and flipping formwork, and overcomes the shortcomings of sliding formwork and flipping formwork construction. Basic principle: Using the sliding formwork system, a distance of 40 cm is set between the outer formwork of the hollow pier body and the enclosure of the sliding formwork system. The outer formwork is supported on the enclosure by adjusting the screw, and the outer formwork is vertically suspended on the bracket by a lifting ring. The installation and removal of the formwork is achieved by adjusting the screw. In order to prevent the formwork from deforming during concrete pouring, the inner formwork is supported by an integral truss, and the outer formwork is additionally provided with tension screws for auxiliary reinforcement.

[0004] To achieve the above object, the present invention provides the following technical solutions: a method for turning and sliding a hollow thin-wall pier, comprising the steps of: construction preparation, roughening the cap before setting out, cleaning it, and setting out the plane position of the pier body on the cap;

[0005] Step 2: Steel bar production and installation;

[0006] Steel bar production:

[0007] (1) The hollow thin-walled pier steel bars are made in the processing shed and installed on site. First, the bent steel bars are straightened. The straightening method of the bent steel bars should be approved by the supervising engineer. The damage of the steel bars after straightening cannot exceed 5% of the cross section. Flame heating is not allowed.

[0008] (2) The steel bars are cut by a steel bar cutting machine, and the bending and hooking are processed by a steel bar bending machine. The allowable deviation of the processed steel bars complies with the specifications;

[0009] (3) All steel bar bending must be carried out at a temperature above +5°C;

[0010] (4) The steel bars shall be bent according to the shape shown in the drawings. The exposed part of the steel bars poured into the concrete shall not be bent at the concrete pouring site. All steel bars shall be cold-bent in the processing plant.

[0011] Steel bar installation:

[0012] (1) After the installation of the cap reinforcement is completed, the cap template is installed, the pier body position is released using a total station, and then the pier body reinforcement is embedded. To ensure the spacing and protective layer of the embedded reinforcement, a circle of positioning reinforcement is installed on the surface reinforcement of the cap. The positioning is required to be accurate and all the embedded reinforcement and the cap surface reinforcement are welded and fixed. The position of each embedded reinforcement is marked on the positioning reinforcement. To prevent the embedded reinforcement of the pier body from sinking, the cap frame reinforcement within the pier body range is welded to the upper and lower main reinforcement of the cap to play a supporting role. To ensure the overall rigidity of the pier body reinforcement skeleton, a layer of pier body stirrups is installed at 1.5m from the top surface of the cap. The temporary positioning stirrups of the pier body are connected to the embedded reinforcement by binding and will be removed when the binding pier body reinforcement skeleton is installed;

[0013] (2) During the construction of the hollow thin-walled pier body reinforcement, two cotton threads are used to draw the center axis of the cap according to the axis position placed in advance. The positioning steel bars are adjusted and fixed according to the position of the cotton threads. The pre-embedded steel bars of the pier body are positioned and tied to the positioning steel bars according to the position of the red oil strokes on the positioning steel bars. If there is interference between the pier body reinforcement and the cap reinforcement, the position of the cap reinforcement must be appropriately adjusted on the premise of ensuring the correct position of the pier body reinforcement, but it must not be arbitrarily cut off;

[0014] (3) For the installed pier body reinforcement skeleton, temporary stabilization measures should be taken before installing the formwork to prevent it from tipping over;

[0015] (4) Before extending the steel bars, the top of the cast layer should be staked out again to ensure the verticality and accuracy of the steel bar installation;

[0016] Step 3: Steel bar protective layer. The steel bar protective layer of hollow thin-walled piers is controlled by using pancake-shaped concrete pads with the same strength as the pier body concrete. The pads are in plum blossom shape and are customized according to the design dimensions of the protective layer in the drawings. The thickness deviation of the protective layer is controlled within ±10mm. The steel bar pads of the pier body are arranged in plum blossom shape when tied. The spacing between pads in the same row is 0.75m, and the number of pads is not less than 4 / m2. The pads are firmly tied to the steel bars with wire ties, and the wire heads of the wire ties must not enter the concrete protective layer.

[0017] Step 4: Embedded parts construction. During the pier construction, due to the need for engineering construction measures, many embedded parts for temporary projects must be buried on the concrete surface. The embedded parts used for construction mainly include tower crane foundation and wall support embedded parts, construction elevators, pedestrian ladders, cap beams and other embedded parts;

[0018] Step 5: System installation and debugging, the operation is as follows,

[0019] (1) Install the enclosure: adjust and install the enclosure according to the plane position of the solid pier and connect them into a whole;

[0020] (2) Install the lifting system, install the lifting bracket, and after the enclosure is fixed, weld the lifting bracket and the enclosure into a whole;

[0021] (3) Install the template. First, install one end of the screw on the enclosure, then put the template in place, connect the screw and the template, and then install the template hanging rod to hang the template on the bracket;

[0022] (4) Install the internal tooth through-hole jack on the top surface of the lifting bracket according to the design position of the climbing pole;

[0023] (5) Install the climbing pole, which passes through the jack and the bracket, and install a clamp ring above the jack to limit the climbing height of the jack;

[0024] (6) Install the operating platform and precision control system. After installing the operating platform and control console, install the pipeline. The pipeline is divided into a main line and a branch line. An oil distribution valve is installed between the main line and the branch line. The pipeline is laid along the circle and goes directly to the jack along the bottom of the bracket chamfer;

[0025] (7) System calibration and debugging: after installation, calibrate the template system and pipeline positioning and fixation first, then start and debug the system;

[0026] Step 6: Pour the first section of concrete. The concrete pouring is carried out by crane or tower crane. The slump and workability of the concrete are strictly controlled during the pouring process. The concrete pouring is carried out synchronously along all sides. The layer thickness is 30cm. Pay attention to the concrete vibration during the pouring process. When vibrating the upper layer of concrete, insert 5-10cm into the lower layer of concrete. Over-vibration or missed vibration is strictly prohibited. After the concrete pouring is completed, the next section of steel bars is directly installed on the platform;

[0027] Step 7: Remove the formwork. After the concrete solidifies, loosen the nut of the screw manually with a wrench, and the formwork slides back horizontally with the screw;

[0028] Step 8: The template system slides up. Before sliding up, first accurately locate the positioning clamp on the fixed climbing rod, start the control console, and the system climbs up. During the climbing process, pay attention to the uniform climbing speed of each climbing rod;

[0029] Step 9: The template is in place and installed. After the template is in place, adjust the lead screw nut, the template slides forward, and automatically closes and installs. After installation, the verticality correction check is carried out, which is mainly controlled by a total station. For the joints between the shaped combined steel templates with too wide joints, and the joints between the side template and the bottom template, use a thin foam sheet and a thin rubber sheet, and fasten them with a U-shaped buckle to prevent leakage of slurry at the joints;

[0030] Step 10: Curing. The curing adopts an automatic sprinkler system. After the water valve is turned on, the sprinkler system installed on the truss automatically cures;

[0031] Step 11: Pour the next section of concrete. After the formwork is in place, adjust the lead screw nut, and the formwork will automatically close and install. After installation, check the verticality.

[0032] Follow the above sequence until the pier top is poured, the operating platform is set up, and the formwork system is dismantled.

[0033] Preferably, the template system includes an inner mold body, an outer mold, a ring, etc. The template adopts a standardized steel template produced by the manufacturer and is assembled on site. The outer mold is 40 cm away from the ring and is connected to the ring with an adjustable screw.

[0034] Preferably, the outer template is 2.0m high, the front width is composed of 2 3.5m templates, the side template is 4.0m wide, the panel is 5mm thick steel plate, the vertical ribs are 12cm channel steel, 9 are arranged on the front, 5 are arranged on the side, and the transverse ribs are 10cm channel steel, 7 are arranged.

[0035] Preferably, the inner mold body is made of 5 mm thick steel plate and supported by an inner integral truss.

[0036] Preferably, the main function of the enclosure is to keep the template in the assembled plane shape and connect the template to the lifting frame as a whole. The enclosure bears the horizontal loads such as the concrete side pressure, impact force and wind load transmitted by the template, and also bears the vertical loads such as the gravity of the lifting template, the static load acting on the operating platform and the construction load, and transmits them to the lifting frame, jack and support rod. The enclosure is welded into a truss with angle steel, with a width and height of 100cm and 150cm respectively, and a horizontal rod spacing of 1m. Angle steel is used to connect the two rods diagonally, and the four angle steels at the corners are L7.5, and the diagonal connecting rods are L5 angle steel.

[0037] Preferably, the operating platform is divided into a construction platform and a decoration platform. The construction platform is arranged on the top surface of the truss to provide necessary space for tying steel bars and pouring concrete. It is supported on the main vertical rods of the lifting frame and is connected to the truss through the lifting frame. The platform is 1.7m wide, and the outer side of the platform is 1.35m fully paved with 5mm thick anti-slip steel plates. The platform 0.35m inside the formwork is connected with an axle pin, and a horizontal limit device is provided. During the construction process, the platform table top can be flipped along the axis as needed to facilitate the removal of the formwork. The protective railings use vertical L7.5 angle steels with a spacing of 1m and a safety net hung. In order to facilitate the construction personnel to check the quality of the concrete after demoulding at any time, immediately repair concrete surface defects, pull out embedded parts, and immediately water the concrete surface for maintenance, two layers of modified platforms are set under the truss, also known as auxiliary plates, with a height of 2m and a width of 0.6m. They are welded with L5 angle steels, and the plate surface is fully paved with 5mm thick anti-slip steel plates, which are suspended under the trusses and lifting frames. The hanger can be made of L7.5 angle steel. In order to ensure safety, protective railings are set on the outside to hang anti-fall safety nets.

[0038] Preferably, the lifting system comprises:

[0039] Support rod: The support rod is made of seamless steel pipe with a diameter of 48mm and a wall thickness of 3.5mm. It is supported in the concrete. The enclosure is lifted by a gantry lifting frame and a jack. The lifting frame is made of 20a I-beam and [10 channel steel is used for diagonal support;

[0040] Jack: 8 jacks are used, 2 are arranged on each side of the inner and outer molds along the bridge. The support rods are all supported in the concrete and staggered on the outside. The jacks use QYD-100 wedge-type hydraulic jacks with a theoretical lifting capacity of 100KN, a working lifting capacity of 50KN, and a stroke of 35cm. The jacks work cyclically through two internal toothed retaining rings to crawl upward along the support rods.

[0041] Preferably, the precision control system is driven by an electric motor and has a built-in warning bell. The operating surface is composed of an ammeter, a voltmeter, a pressure gauge, a hydraulic control cabinet, a jack, a control valve, a main oil pipe, and a branch oil pipe. The sliding height of the jack is fixed by a limiter fixed on the support rod. When the operating system is installed, the inner and outer oil pipes are arranged separately to facilitate the control of the lifting and adjustment of the enclosure and the template.

[0042] Preferably, the power line is provided with a power switch box on the operating platform according to the temporary power requirements, and the water pipes are fixed around the perimeter with curing water to form a spray system for automatic spraying and curing.

[0043] Technical effects and advantages of the present invention:

[0044] 1. Less investment in templates and equipment, reducing costs;

[0045] 2. Fast construction speed, high construction efficiency and good appearance quality

[0046] The high pier self-lifting sliding and flipping construction technology can combine the advantages of sliding formwork and flipping formwork, ensuring that the construction speed is equivalent to that of sliding formwork while achieving the same appearance quality as flipping formwork;

[0047] 3. Fully enclosed structure ensures construction safety

[0048] The main structure is connected to the poured concrete through climbing poles. Its stability is not affected by external factors, and the exterior adopts a fully enclosed structure to ensure construction safety.

[0049] 4. Continuous and uninterrupted construction

[0050] The large-area steel formwork on the outside adopts a multi-layer structure. Once the upper steel bar construction is completed, the formwork installation and concrete pouring can be carried out immediately, enabling continuous and uninterrupted construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a process flow chart of the construction method of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] according to Figure 1 The hollow thin-wall pier flip-slide integrated construction method shown includes step 1: construction preparation, roughening the cap before setting out, cleaning it, and setting out the plane position of the pier body on the cap;

[0054] Step 2: Steel bar production and installation;

[0055] Steel bar production:

[0056] (1) The hollow thin-walled pier steel bars are made in the processing shed and installed on site. First, the bent steel bars are straightened. The straightening method of the bent steel bars should be approved by the supervising engineer. The damage of the steel bars after straightening cannot exceed 5% of the cross section. Flame heating is not allowed.

[0057] (2) The steel bars are cut by a steel bar cutting machine, and the bending and hooking are processed by a steel bar bending machine. The allowable deviation of the processed steel bars complies with the specifications;

[0058] (3) All steel bar bending must be carried out at a temperature above +5°C;

[0059] (4) The steel bars shall be bent according to the shape shown in the drawings. The exposed part of the steel bars poured into the concrete shall not be bent at the concrete pouring site. All steel bars shall be cold-bent in the processing plant.

[0060] Steel bar installation:

[0061] (1) After the installation of the cap reinforcement is completed, the cap template is installed, the pier body position is released using a total station, and then the pier body reinforcement is embedded. To ensure the spacing and protective layer of the embedded reinforcement, a circle of positioning reinforcement is installed on the surface reinforcement of the cap. The positioning is required to be accurate and all the embedded reinforcement and the cap surface reinforcement are welded and fixed. The position of each embedded reinforcement is marked on the positioning reinforcement. To prevent the embedded reinforcement of the pier body from sinking, the cap frame reinforcement within the pier body range is welded to the upper and lower main reinforcement of the cap to play a supporting role. To ensure the overall rigidity of the pier body reinforcement skeleton, a layer of pier body stirrups is installed at 1.5m from the top surface of the cap. The temporary positioning stirrups of the pier body are connected to the embedded reinforcement by binding and will be removed when the binding pier body reinforcement skeleton is installed;

[0062] (2) During the construction of the hollow thin-walled pier body reinforcement, two cotton threads are used to draw the center axis of the cap according to the axis position placed in advance. The positioning steel bars are adjusted and fixed according to the position of the cotton threads. The pre-embedded steel bars of the pier body are positioned and tied to the positioning steel bars according to the position of the red oil strokes on the positioning steel bars. If there is interference between the pier body reinforcement and the cap reinforcement, the position of the cap reinforcement must be appropriately adjusted on the premise of ensuring the correct position of the pier body reinforcement, but it must not be arbitrarily cut off;

[0063] (3) For the installed pier body reinforcement skeleton, temporary stabilization measures should be taken before installing the formwork to prevent it from tipping over;

[0064] (4) Before extending the steel bars, the top of the cast layer should be staked out again to ensure the verticality and accuracy of the steel bar installation;

[0065] Step 3: Steel bar protective layer. The steel bar protective layer of hollow thin-walled piers is controlled by using pancake-shaped concrete pads with the same strength as the pier body concrete. The pads are in plum blossom shape and are customized according to the design dimensions of the protective layer in the drawings. The thickness deviation of the protective layer is controlled within ±10mm. The steel bar pads of the pier body are arranged in plum blossom shape when tied. The spacing between pads in the same row is 0.75m, and the number of pads is not less than 4 / m2. The pads are firmly tied to the steel bars with wire ties, and the wire heads of the wire ties must not enter the concrete protective layer.

[0066] Step 4: Embedded parts construction. During the pier construction, due to the need for engineering construction measures, many embedded parts for temporary projects must be buried on the concrete surface. The embedded parts used for construction mainly include tower crane foundation and wall support embedded parts, construction elevators, pedestrian ladders, cap beams and other embedded parts;

[0067] Step 5: System installation and debugging, the operation is as follows,

[0068] (1) Install the enclosure: adjust and install the enclosure according to the plane position of the solid pier and connect them into a whole;

[0069] (2) Installing the lifting system, installing the lifting bracket, and after the enclosure is fixed, welding the lifting bracket and the enclosure into a whole; the lifting system includes:

[0070] Support rod: The support rod is made of seamless steel pipe with a diameter of 48mm and a wall thickness of 3.5mm. It is supported in the concrete. The enclosure is lifted by a gantry lifting frame and a jack. The lifting frame is made of 20a I-beam and [10 channel steel is used for diagonal support;

[0071] Jack: 8 jacks are used, 2 are arranged on each side of the inner and outer molds along the bridge. The support rods are all supported in the concrete and staggered on the outside. The jacks use QYD-100 wedge-type hydraulic jacks with a theoretical lifting capacity of 100KN, a working lifting capacity of 50KN, and a stroke of 35cm. The jacks work cyclically through two internal toothed retaining rings to crawl upward along the support rods.

[0072] (3) Install the template. First, install one end of the screw on the enclosure, then put the template in place, connect the screw and the template, and then install the template hanging rod to hang the template on the bracket;

[0073] (4) Install the internal tooth through-hole jack on the top surface of the lifting bracket according to the design position of the climbing pole;

[0074] (5) Install the climbing pole, which passes through the jack and the bracket, and install a clamp ring above the jack to limit the climbing height of the jack;

[0075] (6) Install the operating platform and precision control system. After installing the operating platform and control console, install the pipeline. The pipeline is divided into a main line and a branch line. An oil distribution valve is set between the main line and the branch line. The pipeline is laid along the enclosure and directly reaches the jack along the bottom of the bracket chamfer. The precision control system is driven by an electric motor and has an internal warning bell. The operating surface is composed of an ammeter, a voltmeter, a pressure gauge, a hydraulic control cabinet, a jack, a control valve, a main oil pipe, and a branch oil pipe. The sliding height of the jack is fixed by a limiter fixed on the support rod. When installing the operating system, the inner and outer oil pipes are arranged separately to facilitate the lifting and adjustment of the control enclosure and the template;

[0076] The operating platform is divided into a construction platform and a decoration platform. The construction platform is arranged on the top surface of the truss to provide necessary space for tying steel bars and pouring concrete. It is supported on the main vertical rods of the lifting frame and is connected to the truss through the lifting frame. The platform is 1.7m wide, and the outer side of the platform is 1.35m fully paved with 5mm thick anti-slip steel plates. The platform 0.35m inside the formwork is connected with an axle pin, and a horizontal limit device is set. During the construction process, the platform tabletop can be flipped along the axis as needed to facilitate the removal of the formwork. The guardrail uses vertical L7.5 angle steel with a spacing of 1m and a safety net is hung. In order to facilitate the construction personnel to check the quality of the concrete after demoulding at any time, immediately repair the defects on the concrete surface, pull out the embedded parts, and immediately spray water on the concrete surface for maintenance, there are two layers of modified platforms under the truss, also known as auxiliary plates, with a height of 2m and a width of 0.6m. They are welded with L5 angle steels, and the plate surface is fully paved with 5mm thick anti-slip steel plates, which are suspended under the trusses and lifting frames. The hanger can be made of L7.5 angle steel. In order to ensure safety, a guardrail is installed on the outside to hang a safety net to prevent falling.

[0077] (7) System calibration and debugging: after installation, calibrate the template system and pipeline positioning and fixation first, then start and debug the system;

[0078] The template system includes an inner mold body, an outer mold, a ring, etc. The template adopts a standardized steel template produced by the manufacturer and is assembled on site. The outer mold is 40 cm away from the ring and is connected to the ring with an adjustable screw rod.

[0079] The outer formwork is 2.0m high, the front width consists of 2 3.5m formworks, the side formwork is 4.0m wide, the panel is a 5mm thick steel plate, the vertical ribs are 12cm channel steel, 9 are arranged on the front, 5 are arranged on the side, and the transverse ribs are 10cm channel steel, 7 are arranged. The inner mold body is made of 5mm thick steel plate, supported by the inner integral truss.

[0080] The main function of the enclosure is to keep the template in the assembled plane shape and connect the template to the lifting frame into a whole. The enclosure bears horizontal loads such as concrete lateral pressure, impact force and wind load transmitted by the template, and also bears vertical loads such as the gravity of the lifted template, static load acting on the operating platform and construction load, and transmits them to the lifting frame, jack and support rod. The enclosure is welded into a truss with angle steel, with a width and height of 100cm and 150cm respectively, and a spacing of 1m between transverse rods. Angle steel is used to connect the two rods diagonally. The four angle steels at the corners are L7.5, and the diagonal connecting rods are L5 angle steel.

[0081] Step 6: Pour the first section of concrete. The concrete pouring is carried out by crane or tower crane. The slump and workability of the concrete are strictly controlled during the pouring process. The concrete pouring is carried out synchronously along all sides. The layer thickness is 30cm. Pay attention to the concrete vibration during the pouring process. When vibrating the upper layer of concrete, insert 5-10cm into the lower layer of concrete. Over-vibration or missed vibration is strictly prohibited. After the concrete pouring is completed, the next section of steel bars is directly installed on the platform;

[0082] Step 7: Remove the formwork. After the concrete solidifies, loosen the nut of the screw manually with a wrench, and the formwork slides back horizontally with the screw;

[0083] Step 8: The template system slides up. Before sliding up, first accurately locate the positioning clamp on the fixed climbing rod, start the control console, and the system climbs up. During the climbing process, pay attention to the uniform climbing speed of each climbing rod;

[0084] Step 9: The template is in place and installed. After the template is in place, adjust the lead screw nut, the template slides forward, and automatically closes and installs. After installation, the verticality correction check is carried out, which is mainly controlled by a total station. For the joints between the shaped combined steel templates with too wide joints, and the joints between the side template and the bottom template, use a thin foam sheet and a thin rubber sheet, and fasten them with a U-shaped buckle to prevent leakage of slurry at the joints;

[0085] Step 10: Curing. The curing adopts an automatic sprinkler system. After the water valve is turned on, the sprinkler system installed on the truss automatically cures. The power line is equipped with a power switch box on the operating platform according to the temporary power requirements. After the water pipe is fixed around the perimeter with curing water, it is made into a sprinkler system for automatic spray curing.

[0086] Step 11: Pour the next section of concrete. After the formwork is in place, adjust the lead screw nut, and the formwork will automatically close and install. After installation, check the verticality.

[0087] Follow the above sequence until the pier top is poured, the operating platform is set up, and the formwork system is dismantled.

Claims

1. A method for integrated flip-sliding construction of a hollow thin-walled pier, characterized in that: Here are the steps: Step 1: Construction preparation: roughen the foundation before setting out, clean it, and mark the plane position of the pier body on the foundation; Step 2: Steel bar production and installation; Steel bar production: (1) The hollow thin-walled pier steel bars are made in the processing shed and installed on site. First, the bent steel bars are straightened. The straightening method of the bent steel bars should be approved by the supervising engineer. The damage of the steel bars after straightening cannot exceed 5% of the cross section. Flame heating is not allowed. (2) The steel bars are cut by a steel bar cutting machine, and the bending and hooking are processed by a steel bar bending machine. The allowable deviation of the processed steel bars complies with the specifications; (3) All steel bar bending must be carried out at a temperature above +5°C; (4) The steel bars shall be bent according to the shape shown in the drawings. The exposed part of the steel bars poured into the concrete shall not be bent at the concrete pouring site. All steel bars shall be cold-bent in the processing plant. Steel bar installation: (1) After the installation of the cap reinforcement is completed, the cap template is installed, the pier body position is released using a total station, and then the pier body reinforcement is embedded. To ensure the spacing and protective layer of the embedded reinforcement, a circle of positioning reinforcement is installed on the surface reinforcement of the cap. The positioning is required to be accurate and all the embedded reinforcement and the cap surface reinforcement are welded and fixed. The position of each embedded reinforcement is marked on the positioning reinforcement. To prevent the embedded reinforcement of the pier body from sinking, the cap frame reinforcement within the pier body range is welded to the upper and lower main reinforcement of the cap to play a supporting role. To ensure the overall rigidity of the pier body reinforcement skeleton, a layer of pier body stirrups is installed at 1.5m from the top surface of the cap. The temporary positioning stirrups of the pier body are connected to the embedded reinforcement by binding and will be removed when the binding pier body reinforcement skeleton is installed; (2) During the construction of the hollow thin-walled pier body reinforcement, two cotton threads are used to draw the center axis of the cap according to the axis position placed in advance. The positioning steel bars are adjusted and fixed according to the position of the cotton threads. The pre-embedded steel bars of the pier body are positioned and tied to the positioning steel bars according to the position of the red oil strokes on the positioning steel bars. If there is interference between the pier body reinforcement and the cap reinforcement, the position of the cap reinforcement must be appropriately adjusted on the premise of ensuring the correct position of the pier body reinforcement, but it must not be arbitrarily cut off; (3) For the installed pier body reinforcement skeleton, temporary stabilization measures should be taken before installing the formwork to prevent it from tipping over; (4) Before extending the steel bars, the top of the cast layer should be staked out again to ensure the verticality and accuracy of the steel bar installation; Step 3: Steel bar protective layer. The steel bar protective layer of the hollow thin-walled pier is controlled by using a pancake-shaped concrete pad with the same strength as the pier body concrete. The pad is in plum blossom shape and is customized according to the design size of the protective layer in the drawing. The steel bar pads of the pier body are arranged in plum blossom shape when tied. The pads are firmly tied to the steel bars with wire ties, and the wire heads of the wire ties must not enter the concrete protective layer. Step 4: Embedded parts construction. During the pier construction, due to the need for engineering construction measures, many embedded parts for temporary projects must be buried on the concrete surface. The embedded parts used for construction mainly include tower crane foundation and wall support embedded parts, construction elevators, pedestrian ladders, cap beams and other embedded parts; Step 5: System installation and debugging, the operation is as follows, (1) Install the enclosure: adjust and install the enclosure according to the plane position of the solid pier and connect them into a whole; (2) Install the lifting system, install the lifting bracket, and after the enclosure is fixed, weld the lifting bracket and the enclosure into a whole; (3) Install the template. First, install one end of the screw on the enclosure, then put the template in place, connect the screw and the template, and then install the template hanging rod to hang the template on the bracket; (4) Install the internal tooth through-hole jack on the top surface of the lifting bracket according to the design position of the climbing pole; (5) Install the climbing pole, which passes through the jack and the bracket, and install a clamp ring above the jack to limit the climbing height of the jack; (6) Install the operating platform and precision control system. After installing the operating platform and control console, install the pipeline. The pipeline is divided into a main line and a branch line. An oil distribution valve is installed between the main line and the branch line. The pipeline is laid along the circle and goes directly to the jack along the bottom of the bracket chamfer; (7) System calibration and debugging: after installation, calibrate the template system and pipeline positioning and fixation first, then start and debug the system; Step 6: The first section of concrete pouring is carried out by crane or tower crane. The slump and workability of concrete are strictly controlled during the pouring process. Concrete pouring is carried out synchronously along all four sides with a layer thickness of 30cm. Over-vibration or missed vibration is strictly prohibited. After the concrete pouring is completed, the next section of steel bars is directly installed on the platform; Step 7: Remove the formwork. After the concrete solidifies, loosen the nut of the screw manually with a wrench, and the formwork slides back horizontally with the screw; Step 8: The template system slides up. Before sliding up, first accurately locate the positioning clamp on the fixed climbing rod, start the control console, and the system climbs up. During the climbing process, pay attention to the uniform climbing speed of each climbing rod; Step 9: The template is in place and installed. After the template is in place, adjust the lead screw nut, the template slides forward, and automatically closes and installs. After installation, the verticality correction check is carried out, which is mainly controlled by a total station. For the joints between the shaped combined steel templates with too wide joints, and the joints between the side template and the bottom template, use a thin foam sheet and a thin rubber sheet, and fasten them with a U-shaped buckle to prevent leakage of slurry at the joints; Step 10: Curing. The curing adopts an automatic sprinkler system. After the water valve is turned on, the sprinkler system installed on the truss automatically cures; Step 11: Pour the next section of concrete. After the formwork is in place, adjust the lead screw nut, and the formwork will automatically close and install. After installation, check the verticality. Follow the above sequence until the pier top is poured, the operating platform is set up, and the formwork system is dismantled.

2. The method for turning and sliding a hollow thin-wall pier according to claim 1, characterized in that: The template system includes an inner template body, an outer template, a circle, etc. The template adopts a standardized steel template produced by the manufacturer and is assembled on site.

3. The method for turning and sliding a hollow thin-wall pier according to claim 2 is characterized in that: The outer formwork is 2.0m high, the front width consists of 2 3.5m formworks, the side formwork is 4.0m wide, the panel is a 5mm thick steel plate, the vertical ribs are 12cm channel steel, 9 are arranged on the front, 5 are arranged on the side, and the transverse ribs are 10cm channel steel, 7 are arranged.

4. The method for turning and sliding a hollow thin-wall pier according to claim 2, characterized in that: The inner mold body is made of 5mm thick steel plate and supported by an inner integral truss.

5. The method for turning and sliding a hollow thin-wall pier according to claim 2, characterized in that: The main function of the enclosure is to keep the formwork in the plane shape of the assembly and connect the formwork and the lifting frame into a whole. The enclosure bears horizontal loads such as concrete side pressure, impact force and wind load transmitted by the formwork, and also bears vertical loads such as the gravity of the lifted formwork, static load and construction load acting on the operating platform, and transmits them to the lifting frame, jack and support rod.

6. The method for turning and sliding a hollow thin-wall pier according to claim 1, characterized in that: The operating platform is divided into a construction platform and a decoration platform. The construction platform is arranged on the top surface of the truss to provide a necessary space for tying steel bars and pouring concrete. It is supported on the main vertical rods of the lifting frame and is connected to the truss through the lifting frame.

7. The method for turning and sliding a hollow thin-wall pier according to claim 1, characterized in that: The lifting system comprises: Support rod: The support rod is made of seamless steel pipe with a diameter of 48mm and a wall thickness of 3.5mm. It is supported in the concrete, and the enclosure is lifted by a gantry lifting frame and a jack; Jack: 8 jacks are used, with 2 arranged on each side of the inner and outer molds along the bridge. The support rods are all supported in the concrete and staggered on the outside. The jacks work cyclically through two internal toothed clamps to crawl upward along the support rods.

8. The method for turning and sliding a hollow thin-wall pier according to claim 1, characterized in that: The precision control system is driven by an electric motor and has a built-in warning bell. The operating surface is composed of an ammeter, a voltmeter, a pressure gauge, a hydraulic control cabinet, a jack, a control valve, a main oil pipe, and a branch oil pipe. The sliding height of the jack is fixed by a limiter fixed on the support rod. When the operating system is installed, the inner and outer oil pipes are arranged separately to facilitate the control of the lifting and adjustment of the enclosure and the template.

9. The method for turning and sliding a hollow thin-wall pier according to claim 1, characterized in that: The power line is provided with a power switch box on the operating platform according to the temporary power demand, and a water pipe is fixed around the periphery with curing water to form a sprinkler system for automatic spray curing.

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