Cast-in-place beam pier-beam reverse construction method for side pier of cable-stayed swivel bridge

Abstract

According to the pier-beam reverse construction method for the side pier cast-in-place beam of the cable-stayed swivel bridge, a pier column jointly supported by a main bridge cast-in-place beam and an approach bridge cast-in-place beam is constructed in two times, the first time of construction is conducted to the elevation position of the padstone bottom of the main bridge cast-in-place beam, and steel bars needed by the second time of construction of the approach bridge side pier column are reserved during the first time of construction of the pier column. When the first-time concrete strength meets 85% of the design strength, a support of the approach bridge cast-in-place beam is constructed, meanwhile, the position of a tensioning notch of main beam closure prestress is reserved, and meanwhile, it is avoided that a temporary support intrudes into the position of an originally-designed support. A support is erected on a main bridge cast-in-place beam according to design requirements to complete cast-in-place section construction at the position of a side pier and closure block construction after rotation, tensioning grouting and anchor sealing of closure prestressed steel beams are completed after closure block concrete strength meets requirements, and then approach bridge side pier lifting and padstone and support pre-burying construction is completed according to pier column construction requirements. And after the concrete strength of the approach bridge side abutments, the supports and the like reaches the standard, permanent supports are installed, the approach bridge temporary supporting columns are dismantled, the approach bridge cast-in-place beams completely fall on the permanent supports, and system conversion of the approach bridge cast-in-place beams is completed.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a method for reverse construction of cast-in-place beams of side piers of an inclined-stayed swivel bridge. Background Art

[0002] The existing similar construction method of the high and low platform structure of the side pier of the cable-stayed rotating bridge is as follows: ① The side pier with high and low platforms is constructed in two times. The first time is to construct it to the position flush with the top of the low pier of the cast-in-place beam of the main bridge, complete the construction of the cast-in-place section at the side pier position and the construction of the joint block after the rotation, and after the concrete strength of the joint block meets the requirements, complete the tensioning grouting and anchoring of the joint prestressed steel strands, and then complete the raising of the side pier of the approach bridge and the construction of the cast-in-place beam of the approach bridge according to the pier column construction requirements. This method can better adapt to the construction of side piers and beams on both sides with different forms of height differences. However, this conventional sequential operation has the following problems: ① The sequential construction is adopted, and the construction period is long, which is difficult to meet the construction period requirements of short, frequent and fast projects. ② The rental period of machinery and equipment and turnover materials is relatively long, the utilization rate is low, and the construction cost is relatively high. ③ The construction period is extended and the project management cost increases. This reverse construction operation method that breaks the conventional operation is particularly suitable for such pier and beam construction methods with tight construction periods and high and low piers in the side pier design. Summary of the invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for reverse construction of cast-in-place beams of the side piers of a cable-stayed swivel bridge, which adjusts the traditional construction sequence from bottom to top, from pier to beam, and main first and secondary later, avoiding the long construction time required for conventional construction methods. The use of temporary piers realizes the supporting function of the cast-in-place beams, and while realizing the construction of the adjacent cast-in-place beams of the swivel main beam first, it also meets the space for joint closing operations required for the construction of the swivel main beam later. The original sequential construction is adjusted to parallel construction, and the construction tasks on some key lines are adjusted to non-key lines, shortening the length of the key lines, improving the effective utilization rate of mechanical equipment, shortening the rental period of mechanical equipment and materials, and reducing the cost of project management. In addition, the application is more in line with the design intent, and can fully reflect the true significance of the designer setting the joint closing section in the early stage of bridge design.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for reverse construction of cast-in-place beams of side piers of an inclined-stayed swivel bridge, characterized in that it comprises the following steps:

[0006] Step 1, a spiral tube support column filled with concrete, a flange and a stiffening plate of the spiral tube support column, an H-shaped steel for unloading, a wedge-shaped block at the bottom of the beam at the top of the support column, and a template for the wedge-shaped block at the bottom of the beam are arranged at the top of the side pier;

[0007] Step 2: By assembling the above components according to the construction sequence, the pier columns with high and low piers are constructed in two times; the first time, the pier columns are constructed to a position flush with the top of the low pier of the main beam, avoiding the position of the prestressed tensioning notch of the main beam joint, and the plane position and elevation of the temporary support column of the cast-in-place beam of the approach bridge are released on the top of the pier on the side of the approach bridge;

[0008] Step 3. According to the elevation of the top of the side pier of the approach bridge, cut a 609x16mm spiral tube as the support column of the cast-in-place beam of the approach bridge, set a t=10mm, 900x900mm steel plate on the top of the support column as the flange of the support column, and evenly set 8 150x150mm, t=10mm triangular steel plates around the flange and the support column as the stiffening plates of the flange. Intermittent welding is used between the flange steel plate and the supporting spiral tube, and full welding is used between the stiffening plate, the flange and the spiral tube; a circular hole with a diameter of 200mm is opened at the center of the flange as the feeding hole and vibration hole for pouring concrete for the support column, and 4 air outlets with a diameter of 10mm are evenly opened on the flange steel plate at a position 5cm away from the spiral tube wall of the support column, and C50 micro-expansive concrete is poured into the spiral tube from the center hole of the flange and vibrated to compact;

[0009] Step 4: Cut 6 pieces of 25H-shaped steel with a length of 900mm, install three pieces on the top of each support column flange, install the H-shaped steel along the bridge direction, and require it to be centered on the top of the steel pipe support column and close together. Install square wood and bamboo plywood on the top of the H-shaped steel as the outer mold of the wedge block at the bottom of the beam;

[0010] Step 5: According to the cast-in-place beam construction method, the cast-in-place section of the main bridge side pier and the cast-in-place beam of the approach bridge are constructed on the bracket at the same time. After the rotation of the main beam is completed, the main bridge joint section is constructed on the bracket, and after the concrete strength of the joint section reaches the design strength, the main beam joint prestressed beam is constructed, and the prestressed beam is grouted and the tensioning groove is sealed;

[0011] Step 6: Install the high pier steel bars and formwork on the approach bridge side of the side pier top, install the approach bridge pad stone steel bars, pour the high pier concrete on the approach bridge side, and after the concrete strength of the high pier on the approach bridge side reaches 2.5 MPa, install the approach bridge pad stone steel bars, install the bearing embedded bolts, pour the pad stone concrete, and install the spherical bearing on the approach bridge side after the concrete strength meets the requirements;

[0012] Step 7. Use gas cutting to cut the H-shaped steel one by one along the web of the top of the temporary support column to separate the H-shaped steel from the web. Pull out the cut steel one by one from between the bottom of the beam and the temporary support column. Remove the square wood and formwork at the wedge block position at the bottom of the beam at the temporary support. Support the cast-in-place beam on the permanent support to complete the system conversion.

[0013] The lower end of the temporary support column of the cast-in-place beam of the approach bridge is a steel pipe support filled with C50 slightly expansive concrete. The top surface elevation of the steel pipe support column is flush with the top of the side pier of the approach bridge. A flange and a stiffening rib are arranged on the top surface of the steel pipe support column. A 25 I-shaped steel is installed on the top surface of the flange, and a 20 I-shaped steel is installed on the 25 I-shaped steel. A thick bamboo plywood is laid on the 20 I-shaped steel, and a beam bottom wedge block is mounted on the thick bamboo plywood.

[0014] 16 threaded steel bars are arranged in the wedge-shaped block at the bottom of the beam.

[0015] The beneficial effects of the present invention are:

[0016] The present invention is designed to adapt to the cast-in-place box beam with an inner transverse diaphragm. Compared with the conventional steel pipe frame construction, it has the advantages of short construction period, fast construction speed, less investment in manpower, material and financial resources, high material turnover utilization rate, convenient operation, etc.

[0017] 1. Taking the construction of cast-in-place box girder of the main bridge of Chengxiang River Bridge on National Highway 241 as an example, this cast-in-place box girder with inner transverse diaphragm was initially constructed by erecting steel pipe frames, but the economic benefits were significantly improved by adopting this improved inner sliding beam construction method.

[0018] The manpower input has been reduced, and each beam section has been reduced by about 30 working days. The labor wage for each working day is calculated at 260 yuan, and each beam section can save about 7,800 yuan in labor costs. The main bridge of the Chengxiang River Bridge has a total of 4 T-structures, and there are a total of 72 beam sections that can be constructed using this method, which can save about 560,000 yuan in labor costs.

[0019] The investment in temporary steel bar materials is reduced. When conventional steel pipe racks are erected, horse stool bars need to be installed at the bottom of each steel pipe rack. Each beam section requires approximately 260 kg of horse stool bars. Calculated at 6,000 yuan per ton of steel, there are a total of 72 beam sections, which saves approximately 112,000 yuan in steel bar costs for temporary construction.

[0020] The construction period was shortened by 2.5 days for each beam section. There were 72 beam sections in total for the four main piers that were constructed using the modified inner sliding beams, which saved a total of 6 months. The rental fee for each 6015 tower crane was calculated at 40,000 yuan, which saved 240,000 yuan. In addition, the rental fees for other small mechanical equipment and materials, and other indirect costs were all non-negligible expenses.

[0021] 2. Compared with the conventional steel pipe rack construction, the present invention avoids the frequent erection and dismantling of the steel pipe rack, material transportation and other cumbersome construction procedures, and greatly shortens the construction time of each beam section. The cast-in-place box beam of the Chengxiang River Bridge was constructed by erecting a steel pipe rack in the early stage, and the construction period of each beam section was about 15 days. However, this modified inner sliding beam construction was later adopted, and the construction period of each beam section was shortened to 12.5 days, which has a significant guarantee for the entire construction period.

[0022] In the early stage, the steel pipe frame was erected on the steel bars of the bottom plate. When pouring the concrete of the top plate of the box beam, the bottom plate concrete was not solidified. The steel pipe frame had a great disturbance on the bottom plate concrete. The pouring speed of the top plate concrete could only be slowed down during the pouring. Due to the large pouring area and discontinuous pouring, many construction cold joints affected the appearance quality of the concrete. However, when using this modified internal sliding beam construction, the load of the top plate of the box beam is fully transferred from the sliding beam to the completed beam section and hanging basket. When pouring concrete, there will be no disturbance to the floor concrete. At the same time, the concrete pouring speed is appropriately accelerated, avoiding the formation of cold joints and improving the appearance quality of the concrete.

[0023] In summary, the present invention is used to construct a continuous beam with an inner transverse beam, and the front and rear inner molds of the transverse beam are constructed by means of a slideway. The inner molds are installed and removed quickly, the quality of concrete is guaranteed, the construction is safe and reliable, the construction efficiency is improved, the application scope of the hanging basket construction is expanded, and the social benefits are obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the present invention.

[0025] Figure 2 It is a schematic diagram of the present invention.

[0026] Figure 3 It is the side pier construction segment division diagram of the present invention;

[0027] Figure 4 It is a schematic diagram of the plane positions of the support, block and temporary pier at the side pier of the present invention.

[0028] Figure 5 This is a diagram of a temporary buttress on the top of a side pier of the present invention. Figure 6 Schematic diagram of the temporary support column of the cast-in-place beam of the approach bridge, with the lower end of the steel pipe support filled with C50 slightly expansive concrete. Figure 7 Schematic diagram of setting 16 threaded steel bars in the wedge-shaped block at the bottom of the beam. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0030] like Figure 1 , 2 As shown, a method for reverse construction of cast-in-place beams of side piers of a cable-stayed swivel bridge is characterized by comprising the following steps:

[0031] Step 1: Construction preparation

[0032] (1) Based on the actual conditions of the cast-in-place beam construction site, a qualified design unit is commissioned to design the cast-in-place beam support system and temporary support columns for the approach bridge, calculate the strength, rigidity and stability of the support system, and ensure that the cast-in-place beam support construction is safe and reliable.

[0033] (2) The technical director shall organize technical personnel to study the construction drawings and specifications together. After the construction plan is approved, the technical personnel and relevant management personnel shall be organized to study the core content of the plan together, master the key points of construction control, and complete the briefing work for the workers.

[0034] (3) Determine the resource allocation and on-site preparation of personnel, materials, and machinery based on the construction plan.

[0035] Step 2: First construction of side piers;

[0036] First, divide the pier construction sections, and construct the shadow part to meet the bottom elevation of the main beam support pad stone to meet the main beam construction needs. The pier on one side of the approach bridge to be raised structure should be prepared with steel bars and joints reserved according to the design requirements. Figure 3 .

[0037] Step 3: Setting up temporary piers for cast-in-place beams of approach bridge;

[0038] The plane longitudinal position of the temporary support column is kept consistent with the permanent support line of the cast-in-place beam of the approach bridge in the mileage direction, and the horizontal position is as close to the permanent support position as possible without affecting the prestressing construction of the main beam, so as to ensure the best stress state of the cast-in-place beam when supported by the temporary support column. Taking a pier column of this project as an example, according to the working space and position of the prestressing construction of the main beam on the pier column, the temporary support column is horizontally set at a position with an offset of 2.5m, see Figure 4 shown.

[0039] The temporary support column system consists of beam bottom wedge blocks, supporting square timber, H-shaped steel, and concrete-filled steel pipe support columns from top to bottom. In order to improve the bearing capacity of the steel pipe support columns, C50 micro-expansive concrete is poured into the steel pipe support columns, and stiffening plates are added between the steel pipe support columns and the flange steel plate brackets at the top of the columns.

[0040] The temporary support steel pipe column adopts Ф609×16 spiral pipe. The steel pipe column is placed on the top surface of the first completed pier. To prevent the steel pipe support column from sliding, the steel pipe support is welded and fixed to the embedded steel bars on the top of the pier. The top elevation of the steel pipe support column is flush with the top of the pier column on the approach bridge side to facilitate the removal of the temporary support column in the later stage. Flanges and stiffening ribs are set on the top of the spiral pipe to improve the supporting performance of the flange of the steel pipe column. The concrete pouring in the steel pipe support column requires denseness without shrinkage. A feeding hole is set in the middle of the top seat plate on the top surface of the steel pipe support column to facilitate vibration and exhaust during concrete pouring to ensure the density of concrete in the steel pipe column.

[0041] Step 4: Construction of cast-in-place beams of approach bridge;

[0042] (1) After the construction of temporary piers is completed, the cast-in-place support formwork system of the approach bridge is immediately set up. The cast-in-place beam support adopts Z-shaped disc-type support for cast-in-place construction. On the top of the support, an I14 I-beam distribution beam is placed in the cross direction of the bridge, and then 10cm×10cm square timber is laid on it in the direction of the bridge. A 15mm thick plywood bottom formwork is laid on the square timber to ensure that the support system has sufficient bearing capacity and a stable structural state. At the same time, attention should be paid to strengthening the connection of the support system at the temporary piers. Figure 5 .

[0043] (2) After the pre-stressing of the formwork is completed and the pre-arch adjustment is carried out, the beam reinforcement engineering and prestressing construction are carried out. The order of reinforcement installation construction is: bottom plate → cross beam → web plate → partition plate → supporting inner formwork → top plate → embedded parts.

[0044] (3) When pouring the concrete of the beam body, pour it longitudinally from low to high and from large deformation to small deformation, and pour it horizontally symmetrically. The concrete of the beam top plate and flange plate is spread and vibrated at one time. After the concrete pouring is completed and the second slurry is collected, the roughening equipment is used to roughen the concrete of the beam surface in a timely manner. Then, a special person is assigned to do the maintenance work of the concrete.

[0045] (4) After the concrete strength of the beam body meets the conditions for prestressing construction, the prestressing tendons of the beam body are tensioned in the order of longitudinal → transverse, first the long tendons, then the short tendons, first the web, then the bottom plate, and finally the top plate. At the same time, all longitudinal prestressing tendons are tensioned in accordance with the principle of "left-right symmetry and simultaneous tension at both ends" to complete the prestressing construction.

[0046] (5) After concrete pouring, non-load-bearing formwork should be removed after the concrete strength reaches 2.5 MPa. The support and bottom formwork of the load-bearing formwork must be removed after the prestressing is established. The removal order follows: flange plate → web plate → bottom plate, and it should be removed symmetrically from the mid-span to the piers at both ends.

[0047] Step 5: Construction of cast-in-place beams of the main bridge;

[0048] (1) The cast-in-place section of the side pier of the main bridge is cast-in-place using a full-bridge bracket. The bracket also uses a heavy-duty disc bracket formwork system. During the construction of the cast-in-place section, attention should be paid to reserving the embedded steel plates required for locking the rotating and closure sections. The positioning of the prestressed pipe must be accurate to ensure that it corresponds to the position of the rotating beam section to prevent misalignment during the positioning and installation of the prestressed pipe.

[0049] (2) The locking of the joint section adopts the "external rigid skeleton locking" scheme. The rigid skeleton connecting steel plates are pre-buried in advance during the construction of the segments on both sides of the joint section. Continuous observation (once every 2 hours) is carried out 48 hours before the concrete pouring of the joint section to understand the change pattern of the joint mouth elevation and distance length. The concrete pouring time should be selected when the temperature is the lowest on the day and the temperature rises slowly after pouring. The 67m3 concrete of the joint section is controlled to be poured within 5 hours, and a special person is assigned to carry out maintenance.

[0050] (3) After the joint section is poured, when the concrete strength reaches the design requirements, the prestressing of the joint section begins. The prestressing sequence is longitudinal first, then transverse, and finally vertical. Before starting the prestressing, the rigid skeleton locked in the joint section is released to ensure that the concrete in the joint section can be compressed and deformed freely when the prestressing of the joint section is tensioned.

[0051] (4) After the prestressing strength meets the requirements, remove the brackets of the joint section and the cast-in-place section, loosen the top support on the bracket, separate the joint section formwork from the beam concrete, and then remove the brackets and formwork of the cast-in-place section and the joint section, and drop the beam.

[0052] Step 6: Secondary construction of side piers;

[0053] After the formwork support except for the temporary piers near the cast-in-place beam support of the approach bridge is removed, the side pier supporting the approach bridge end is raised according to the design requirements, and the remaining pier body, cast-in-place beam support pad stone, pier top block, pier side damper, lightning protection grounding terminal and other construction are completed. The outer side of the pier body is designed to be enclosed with a layer of steel plate. The steel plate is used as the permanent structure of the pier column, and the pier column formwork can be constructed with the help of the outer steel plate. After the construction of the pier column steel plate, steel bars and concrete is completed, the topcoat is sprayed. According to the design requirements, the topcoat color should be consistent with the concrete color.

[0054] Step 7: conversion of cast-in-place beam system of approach bridge;

[0055] After the prestressed construction of the main beam is completed and the tensioning grooves are sealed, the secondary concrete of the approach bridge side piers and the concrete strength of the approach bridge support pads reach the design requirements, the embedded bolts of the permanent supports on the approach bridge side are tightened one by one, and the connecting bolts between the upper and lower seat plates of the supports are loosened. The formwork of the temporary support columns of the approach bridge and the wedge-shaped blocks at the bottom of the top beam that are exposed on the concrete surface of the pier top are cut and removed to complete the conversion of the cast-in-place beam system of the approach bridge.

[0056] like Figure 6As shown, the lower end of the temporary support column of the cast-in-place beam of the approach bridge is a steel tube support filled with C50 slightly expansive concrete. The top surface elevation of the steel tube support column is flush with the top of the side pier column of the approach bridge. A flange and a stiffening rib are arranged on the top surface of the steel tube support column. A 25 I-shaped steel is installed on the top surface of the flange. A 20 I-shaped steel is installed on the 25 I-shaped steel. A thick bamboo plywood is laid on the 20 I-shaped steel, and a beam bottom wedge block is set on the thick bamboo plywood.

[0057] like Figure 7 As shown, 16 threaded steel bars are arranged in the wedge-shaped block at the bottom of the beam.

[0058] Example

[0059] The Chengxiang River Bridge of the National Highway 241 Line Realignment Project from Beiwang Township to the County Seat in Fushan County:

[0060] 1. Project Overview

[0061] The eastern extension of Xinyang Avenue is a main urban road in the core area of ​​Yangqu County. It starts from Shouyi Road in the west and ends at Shuangyang Road in the east. The road runs east-west with a red line width of 30 to 35 meters. It is a newly built road, and an overpass scheme is adopted at the Yangqu railway station node.

[0062] The total length of the upper bridge is 540m, with a design mileage range of K1+345.726~K1+885.726, a total of four sections, and the span arrangement is: 2×43m continuous box beam + 2×39m continuous box beam + (2×150)m single-tower cable-stayed rotating bridge + 2×35m continuous box beam. The main bridge deck width is 26.18m, and the approach bridge deck width is 19~26.18m.

[0063] The side piers of the main bridge are 4# and 6#, the main beam is 3.5m high, and the two cast-in-place beams adjacent to the main beam are the second 2×39m continuous box beam with a beam height of 2.5m and the fourth 2×35m continuous box beam with a beam height of 2.0m, so the 4# and 6# side piers are designed as high-low platforms. The top and bottom plates of the cast-in-place beams of the approach bridge are prestressed in a single-end tensioning in the box, while the top plate of the main beam is tensioned in a single-end tensioning in the box, and the bottom plate is tensioned in the beam segment.

[0064] 2. Application effect

[0065] The cable-stayed rotating bridge across the Beitongpu Railway was constructed using the improved pier-beam reverse construction method, which achieved the purpose of parallel construction of the rotating main beam and the cast-in-place beam of the adjacent approach bridge, greatly shortened the construction period, improved the effective utilization rate of machinery and equipment, reduced the time cost of project management, achieved good economic and social benefits, and had a good application effect.

[0066] The improved construction method does not need to calculate the construction time of the adjacent approach bridge cast-in-place beams and bridge deck accessories separately. Traditional construction requires the completion of the construction and tensioning of the low-level pier beams before the high-level piers and the approach bridge body can be raised. The time required from the start of the high-level pier construction to the completion of the adjacent cast-in-place beams and accessories is calculated as follows: 10 days for high pier construction, 7 days for the construction of the side pads and supports of the approach bridge, 2 days for the installation of the bottom formwork and end formwork of the approach bridge cast-in-place beam at the side pier, 30 days for the construction of the approach bridge cast-in-place beam steel bars and concrete, 7 days for the curing of the approach bridge cast-in-place beam concrete, 7 days for the prestressing and grouting of the approach bridge cast-in-place beam, 5 days for the prestressing grouting curing, 5 days for the removal of the bridge bracket, and 15 days for the approach bridge deck accessory structure. Compared with the traditional construction method, the improved construction method can save 88 days, about 3 months, without considering the influence of any uncontrollable factors.

[0067] Conventional construction methods After the main bridge girder construction is completed, in order to complete the construction in the shortest time, the two approach bridges are usually constructed simultaneously. Each approach bridge is calculated based on an average of two 25t truck cranes, which requires a total of 25t truck cranes for 12 months. The rental fee of each 25t truck crane is calculated at 36,000 yuan, which requires a rental fee of 432,000 yuan; the construction unit management fee is calculated at 600,000 yuan per month, which requires 1.8 million yuan for 3 months. Without considering other expenses, under the two expenses of project management fees and large construction machinery fees, the improved pier-beam reverse construction method saves about 2.432 million yuan compared with the traditional method.

Claims

1. A method for reverse construction of cast-in-place beams of side piers of a cable-stayed swivel bridge, characterized in that: The following steps are involved: Step 1, a spiral tube support column filled with concrete, a flange and a stiffening plate of the spiral tube support column, an H-shaped steel for unloading, a wedge-shaped block at the bottom of the beam at the top of the support column, and a template for the wedge-shaped block at the bottom of the beam are arranged at the top of the side pier; Step 2: By assembling the above components according to the construction sequence, the pier columns with high and low piers are constructed in two times; the first time, the pier columns are constructed to a position flush with the top of the low pier of the main beam, avoiding the position of the prestressed tensioning notch of the main beam joint, and the plane position and elevation of the temporary support column of the cast-in-place beam of the approach bridge are released on the top of the pier on the side of the approach bridge; Step 3. According to the elevation of the top of the side pier of the approach bridge, cut a 609x16mm spiral tube as the support column of the cast-in-place beam of the approach bridge, set a t=10mm, 900x900mm steel plate on the top of the support column as the flange of the support column, and evenly set 8 150x150mm, t=10mm triangular steel plates around the flange and the support column as the stiffening plates of the flange. Intermittent welding is used between the flange steel plate and the supporting spiral tube, and full welding is used between the stiffening plate, the flange and the spiral tube; a circular hole with a diameter of 200mm is opened at the center of the flange as the feeding hole and vibration hole for pouring concrete for the support column, and 4 air outlets with a diameter of 10mm are evenly opened on the flange steel plate at a position 5cm away from the spiral tube wall of the support column, and C50 micro-expansive concrete is poured into the spiral tube from the center hole of the flange and vibrated to compact; Step 4: Cut 6 pieces of 25H-shaped steel with a length of 900mm, install three pieces on the top of each support column flange, install the H-shaped steel along the bridge direction, and require it to be centered on the top of the steel pipe support column and close together. Install square wood and bamboo plywood on the top of the H-shaped steel as the outer mold of the wedge block at the bottom of the beam; Step 5: According to the cast-in-place beam construction method, the cast-in-place section of the main bridge side pier and the cast-in-place beam of the approach bridge are constructed on the bracket at the same time. After the rotation of the main beam is completed, the main bridge joint section is constructed on the bracket, and after the concrete strength of the joint section reaches the design strength, the main beam joint prestressed beam is constructed, and the prestressed beam is grouted and the tensioning groove is sealed; Step 6: Install the high pier steel bars and formwork on the approach bridge side of the side pier top, install the approach bridge pad stone steel bars, pour the high pier concrete on the approach bridge side, and after the concrete strength of the high pier on the approach bridge side reaches 2.5 MPa, install the approach bridge pad stone steel bars, install the bearing embedded bolts, pour the pad stone concrete, and install the spherical bearing on the approach bridge side after the concrete strength meets the requirements; Step 7. Use gas cutting to cut the H-shaped steel one by one along the web of the top of the temporary support column to separate the H-shaped steel from the web. Pull out the cut steel one by one from between the bottom of the beam and the temporary support column. Remove the square wood and formwork at the wedge block position at the bottom of the beam at the temporary support. Support the cast-in-place beam on the permanent support to complete the system conversion.

2. The method for reverse construction of cast-in-place beams of side piers of a cable-stayed rotating bridge according to claim 1 is characterized in that: The lower end of the temporary support column of the cast-in-place beam of the approach bridge is a steel pipe support filled with C50 slightly expansive concrete. The top surface elevation of the steel pipe support column is flush with the top of the side pier of the approach bridge. A flange and a stiffening rib are arranged on the top surface of the steel pipe support column. A 25 I-shaped steel is installed on the top surface of the flange, and a 20 I-shaped steel is installed on the 25 I-shaped steel. A thick bamboo plywood is laid on the 20 I-shaped steel, and a beam bottom wedge block is mounted on the thick bamboo plywood.

3. The reverse construction method of the cast-in-place beam of the side pier of the inclined-stayed rotating bridge according to claim 1 is characterized in that: 16 threaded steel bars are arranged in the wedge-shaped block at the bottom of the beam.

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