Semi-floating system cable-stayed bridge main tower construction process

Abstract

The invention relates to the technical field of cable-stayed bridge main tower construction, in particular to a semi-floating system cable-stayed bridge main tower construction technology. The technical problems that in the prior art, concrete is prone to cracking, a mode of fully laying a support is adopted for construction of a cross beam, the disassembly and assembly difficulty is large, and the support is prone to deformation are solved through the semi-floating system cable-stayed bridge main tower construction technology. According to the technical scheme, the semi-floating system cable-stayed bridge main tower construction technology comprises the following steps that S1, a lower tower column is constructed; s2, cross beam construction; s3, construction of an upper tower column; and S4, construction of the cableway pipe. In order to prevent large-volume concrete temperature cracks in the construction period, control the temperature of the large-volume concrete temperature cracks, reduce internal stress caused by temperature change to the maximum extent and prevent the cracks and serious structural damage, a supporting system combining the pre-buried brackets and the steel pipe columns is adopted for construction of the cross beams, and compared with a fully-laid support, the construction efficiency is improved. The support is small in elastic and inelastic deformation and easy to construct and control.

Description

Technical Field

[0001] The invention relates to the technical field of cable-stayed bridge main tower construction, and in particular to a semi-floating system cable-stayed bridge main tower construction process. Background Art

[0002] With the continuous development of my country's economy, my country is also building a large number of bridges. Bridges mainly cross rivers and roads. In particular, large-span bridges are needed to cross large rivers. Cable-stayed bridges, also known as cable-stayed bridges, are a type of bridge in which the main beam is directly pulled on the bridge tower by many cables. It is a structural system composed of pressure-bearing towers, tensioned cables and bending beams. It can be seen as a multi-span elastically supported continuous beam with cables replacing piers. It can reduce the bending moment in the beam body, lower the building height, reduce the structural weight, and save materials. It can be said that cable-stayed bridges are now In the mainstream development direction of large-span bridges, cable-stayed bridges are composed of main towers, main beams and cable-stayed cables. The construction of the main tower of a cable-stayed bridge includes the construction of the lower tower column, the construction of the crossbeam, the construction of the upper tower column and the construction of the cable duct. The construction of the main tower of a cable-stayed bridge is a key link in the construction of a cable-stayed bridge. The level of main tower construction technology directly affects the construction and use of the entire bridge. However, the existing construction technology does not accurately control the temperature of the concrete during the pouring process, and the concrete is prone to cracks. In addition, the construction of the crossbeam adopts a full-paved bracket method, which makes disassembly and assembly difficult, and the bracket is prone to deformation. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a semi-floating system cable-stayed bridge main tower construction process, which aims to solve the technical problems that concrete is prone to cracks under the prior art, the construction of the crossbeam adopts a full-paved bracket method, which makes disassembly and assembly difficult, and the bracket is easily deformed.

[0004] The technical solution of the present invention is: a construction process for the main tower of a semi-floating cable-stayed bridge, the steps of which are as follows:

[0005] S1: Lower tower column construction

[0006] S11: Clean the construction site where concrete is to be poured, set up the support, material yard and pile positions, and measure the reference points according to the requirements of the design drawings;

[0007] S12: Cement, sand, gravel and water are mixed into concrete by a mixer;

[0008] S13: Define the pouring area, install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfer bars and hook bars. Then lay the formwork around the pouring area, fix the formwork support rods and bottom plate connectors, and make overall adjustments according to the design requirements.

[0009] S14: Pump concrete from a pump truck and pour it into the formwork at a uniform speed, using one-time continuous pouring;

[0010] S15: After the concrete is poured, vibrate and maintain;

[0011] S2: Beam construction, bury the corbels in the tower body that has been poured at both ends of the upper beam, place the steel pipe column on the lower beam, and then lay the distribution beam and template on the corbels and the steel pipe column. The prestressing tension control of the beam, first of all, the installation and positioning of the plastic corrugated pipe, the corrugated pipe is positioned on the frame after the installation of the rigid frame, and fixed with steel bars at the joints. When tying the transverse stirrups of the main reinforcement to the corrugated pipe, tie the anti-collapse steel bars of the corrugated pipe at the same time. Secondly, when installing the anchor seat, first temporarily fix the anchor seats on the main reinforcement or stirrups one by one, and Connect the corrugated pipe and fix it to the notch template with bolts. To prevent the corrugated pipe from leaking, insert a rubber hose into the corrugated pipe after the anchor seat is installed and pull it out after the concrete is initially set. If the corrugated pipe is deformed, it should be handled immediately. Before tensioning, the bundles are threaded. Each bundle has dozens of strands, which are divided into several small bundles and threaded several times. Each small bundle is buried with a sparse handle and tied in one section. The manual threading method is adopted, and finally the prestressing is carried out. Due to the large tensioning tonnage and small curvature radius, in order to ensure that each steel strand is evenly stressed, it is tensioned in batches;

[0012] S3: Construction of upper tower column

[0013] S31: Install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfer bars and hook bars. Install the first section of the formwork and reinforce it. Use the same mix ratio of concrete as in S12 for pouring and curing.

[0014] S32: Install the second section of the formwork, vibrate and cure after pouring, then roughen and turn the formwork up to pour the third section, then turn the formwork over again to complete the pouring of the penultimate section, and finally pour the top layer, then vibrate and cure;

[0015] S4: Construction of cableway pipe

[0016] S41: Ground installation

[0017] S411: Divide the rigidity of the rigid frame into sections, and use AutoCAD graphics software to perform theoretical analysis on each section, taking into account the weight of the cableway tube and the rigid frame, the lifting capacity of the tower crane, and the factors affecting the overall rigidity of the rigid frame;

[0018] S412: Construction data collection, using AutoCAD graphics software to draw three-dimensional graphics and obtain the spatial coordinates and relative coordinates of each point;

[0019] S413: According to the maximum width and length of the rigid frame, a ground installation platform is manufactured on site;

[0020] S414: Make and install a center point locator, and find the center point of the space between the upper and lower ends of the cableway pipe through the center point locator;

[0021] S415: The projection position of the outer edge line, center line, and center points of the upper and lower openings of the cableway pipe on the construction platform;

[0022] S416: Install the rigid frame on the platform according to the platform's contour line and center line. Use a truck crane for installation and make adjustments through simple levers and manual work.

[0023] S417: Install the cableway pipe. Determine the position of the cableway pipe according to the projection center point on the platform and the height between the center points of the upper and lower ends of the cableway pipe and the projection surface. Use a car crane to install it. Use a simple lever and manual adjustment. After the adjustment is completed, fix the cableway pipe on the frame.

[0024] S418: Move the installed cableway pipe and the frame out of the installation platform using a truck crane;

[0025] S419: Install the next section of the cableway pipe;

[0026] S42: High altitude installation

[0027] S421: Weld the positioning steel plate on the top surface of the rigid frame that has been installed at high altitude, and then check the top surface elevation. If the elevation deviation is large, make necessary adjustments by cutting or padding. On the positioning steel plate, lay out the outer edge of the frame to be installed;

[0028] S422: Installation in place: Use a tower crane to hoist the cableway pipe and rigid frame installed on the ground and install them on the positioning plate on the top surface of the previous rigid frame. According to the positioning line on the positioning plate, the rigid frame is rigidly positioned and preliminarily welded.

[0029] S423: Verify the coordinates of the center points of the upper and lower openings of the cableway pipe. The measurement adopts the forced centering three-dimensional measurement technology. The total station is used to measure the coordinates of the sharp point of the center point positioner. The total station observation platform is set as a permanent support platform.

[0030] S424: According to the three-dimensional measurement and verification data, if the deviation is greater than the allowable value, timely adjustment should be made. The adjustment measures are to cut some welding points, use a hand chain hoist to correct the position of the cableway pipe, and then measure and verify. After the verification requirements, weld the cut points and reinforce the welding;

[0031] S425: Take out the center positioner;

[0032] S426: Construct the main tower concrete, and then install the next section of the cableway pipe;

[0033] Preferably, the cement is silicate cement, sulphoaluminate cement or slag cement; the sand is fine sand or medium sand; and the diameter of the crushed stone is 5 to 40 mm.

[0034] Preferably, the temperature control method during concrete pouring includes: (1) using low-temperature water to rinse or spray the formwork before pouring the concrete; (2) adding a cooling agent to the concrete during pouring; (3) adding ice cubes, ice water or distilled water to the concrete.

[0035] Preferably, when pouring the lower tower column and the upper tower column, a chute needs to be hung to assist in pouring, the chute is arranged at a spacing of 1.5m to 2m, and the falling height of the concrete does not exceed 2m.

[0036] Preferably, the concrete is cured by covering it with sacks or geotextiles and then sprinkling water on it to moisten it. The curing is carried out within 12 hours after the pouring is completed. The curing time of the lower tower column is not less than 24 days, and the curing time of each section of the upper tower column is not less than 7 days.

[0037] Preferably, the concrete is vibrated using an inserted vibrator, the moving distance of the vibrator does not exceed 1.5 times the action radius of the vibrator, and the vibrator is kept at a distance of 50 to 100 mm from the side form, and the vibration time is 25 to 35 seconds.

[0038] As a preferred method, the installation of the rigid frame in S13 is divided into two steps: (1) When the rigid frame is initially positioned on site, a short angle steel of the same type is pre-welded to the inner side of the vertical angle steel at the top of the installed small-section truss as an installation positioning code for the bottom of the extended truss. Then, the small-section truss is lifted by a lifting device and slowly approached to the installed truss so that the bottom of the vertical angle steel is close to the short angle steel used as the installation positioning code. The plane position, single-section inclination angle and top elevation of the installed truss are measured, and adjustments are made according to the measurement results. When the truss position is full, After the requirements are met, the lower end of the truss vertical angle steel is immediately welded to the short angle steel of the positioning code, and the initial positioning of the truss is completed; (2) The horizontal connection of the rigid frame is accurately positioned. After the small-section truss is extended and initially positioned, the horizontal connection angle steel is welded. First, the horizontal positioning angle steel is welded on the truss, and the horizontal position control point of the vertical main reinforcement of the lower tower column is marked on the horizontal positioning angle steel to determine the horizontal position edge line of the main reinforcement; then, the horizontal connection angle steel is installed and welded according to the horizontal position edge line of the main reinforcement, and horizontal bracing is added according to the length of the horizontal connection angle steel.

[0039] Preferably, the steps for binding the main reinforcement are: after the rigid frame is installed, install the horizontal positioning angle steel on the rigid frame, and mark out the horizontal edge position control points of the inner and outer main reinforcements on the horizontal positioning angle steel; weld and connect the inner and outer connecting angle steels according to the control points on the horizontal positioning angle steel; mark out the spacing and position of the inner and outer main reinforcements on the connecting angle steel, and extend and fix the inner and outer main reinforcements.

[0040] Preferably, the steps for tying the horizontal reinforcement and chamfered reinforcement are as follows: after each row of main reinforcement is extended, start tying the horizontal reinforcement, first make horizontal reinforcement marks on the main reinforcement, and then tie the horizontal reinforcement in a plum blossom shape. The steel bar tying spacing should meet the design requirements, and the main reinforcement should be tied securely. After all the segmental horizontal reinforcements are tied, mark the horizontal reinforcement and main reinforcement according to the design position and inclination angle, and then tie the chamfered reinforcement and tie it securely to the horizontal reinforcement.

[0041] Preferably, the steps for tying the hook reinforcement are as follows: after the chamfer reinforcement is tied, the hook reinforcement is set and tied according to the intersection of the main reinforcement and the horizontal stirrups. The binding must be firm, and the hooks at both ends of the hook reinforcement must be hooked on the outside of the vertical main reinforcement and the horizontal annular reinforcement.

[0042] Beneficial effects of the present invention:

[0043] 1. In order to prevent large-volume concrete temperature cracks during the construction period, the temperature is controlled to ensure that the temperature is kept within the appropriate range required by the technical specifications. The appropriate temperature is conducive to the formation and development of the internal structure of the concrete, and can minimize the internal stress caused by temperature changes, prevent cracks and serious structural damage. The construction of the beam adopts a support system combining pre-buried brackets and steel pipe columns. Compared with the full-paved bracket, this method is easy to disassemble and assemble, the bracket has small elastic and inelastic deformation, and is easy to control during construction;

[0044] 2. Use a construction process that combines ground installation with high-altitude installation, make a center point locator, and use the center points of the upper and lower ends of the cableway pipe as positioning control points to reduce the workload of high-altitude operations and reduce safety risks. It is easy to operate and requires less manpower. Ground installation can be carried out in advance, speeding up the construction progress. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the embodiments.

[0046] The present invention provides an embodiment: a construction process for a main tower of a semi-floating cable-stayed bridge, the steps of which are as follows:

[0047] S1: Lower tower column construction

[0048] S11: Clean the construction site where concrete is to be poured, set up the support, material yard and pile positions, and measure the reference points according to the requirements of the design drawings;

[0049] S12: Cement, sand, gravel and water are mixed into concrete by a mixer;

[0050] S13: Define the pouring area, install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfer bars and hook bars. Then lay the formwork around the pouring area, fix the formwork support rods and bottom plate connectors, and make overall adjustments according to the design requirements.

[0051] S14: Pump concrete from a pump truck and pour it into the formwork at a uniform speed, using one-time continuous pouring;

[0052] S15: After the concrete is poured, vibrate and maintain;

[0053] S2: Beam construction, bury the corbels in the tower body that has been poured at both ends of the upper beam, place the steel pipe column on the lower beam, and then lay the distribution beam and template on the corbels and the steel pipe column. The prestressing tension control of the beam, first of all, the installation and positioning of the plastic corrugated pipe, the corrugated pipe is positioned on the frame after the installation of the rigid frame, and fixed with steel bars at the joints. When tying the transverse stirrups of the main reinforcement to the corrugated pipe, tie the anti-collapse steel bars of the corrugated pipe at the same time. Secondly, when installing the anchor seat, first temporarily fix the anchor seats on the main reinforcement or stirrups one by one, and Connect the corrugated pipe and fix it to the notch template with bolts. To prevent the corrugated pipe from leaking, insert a rubber hose into the corrugated pipe after the anchor seat is installed and pull it out after the concrete is initially set. If the corrugated pipe is deformed, it should be handled immediately. Before tensioning, the bundles are threaded. Each bundle has dozens of strands, which are divided into several small bundles and threaded several times. Each small bundle is buried with a sparse handle and tied in one section. The manual threading method is adopted, and finally the prestressing is carried out. Due to the large tensioning tonnage and small curvature radius, in order to ensure that each steel strand is evenly stressed, it is tensioned in batches;

[0054] S3: Construction of upper tower column

[0055] S31: Install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfer bars and hook bars. Install the first section of the formwork and reinforce it. Use the same mix ratio of concrete as in S12 for pouring and curing.

[0056] S32: Install the second section of the formwork, vibrate and cure after pouring, then roughen and turn the formwork up to pour the third section, then turn the formwork over again to complete the pouring of the penultimate section, and finally pour the top layer, then vibrate and cure;

[0057] S4: Construction of cableway pipe

[0058] S41: Ground installation

[0059] S411: Divide the rigidity of the rigid frame into sections, and use AutoCAD graphics software to perform theoretical analysis on each section, taking into account the weight of the cableway tube and the rigid frame, the lifting capacity of the tower crane, and the factors affecting the overall rigidity of the rigid frame;

[0060] S412: Construction data collection, using AutoCAD graphics software to draw three-dimensional graphics and obtain the spatial coordinates and relative coordinates of each point;

[0061] S413: According to the maximum width and length of the rigid frame, a ground installation platform is manufactured on site;

[0062] S414: Make and install a center point locator, and find the center point of the space between the upper and lower ends of the cableway pipe through the center point locator;

[0063] S415: The projection position of the outer edge line, center line, and center points of the upper and lower openings of the cableway pipe on the construction platform;

[0064] S416: Install the rigid frame on the platform according to the platform's contour line and center line. Use a truck crane for installation and make adjustments through simple levers and manual work.

[0065] S417: Install the cableway pipe. Determine the position of the cableway pipe according to the projection center point on the platform and the height between the center points of the upper and lower ends of the cableway pipe and the projection surface. Use a car crane to install it. Use a simple lever and manual adjustment. After the adjustment is completed, fix the cableway pipe on the frame.

[0066] S418: Move the installed cableway pipe and the frame out of the installation platform using a truck crane;

[0067] S419: Install the next section of the cableway pipe;

[0068] S42: High altitude installation

[0069] S421: Weld the positioning steel plate on the top surface of the rigid frame that has been installed at high altitude, and then check the top surface elevation. If the elevation deviation is large, make necessary adjustments by cutting or padding. On the positioning steel plate, lay out the outer edge of the frame to be installed;

[0070] S422: Installation in place: Use a tower crane to hoist the cableway pipe and rigid frame installed on the ground and install them on the positioning plate on the top surface of the previous rigid frame. According to the positioning line on the positioning plate, the rigid frame is rigidly positioned and preliminarily welded.

[0071] S423: Verify the coordinates of the center points of the upper and lower openings of the cableway pipe. The measurement adopts the forced centering three-dimensional measurement technology. The total station is used to measure the coordinates of the sharp point of the center point positioner. The total station observation platform is set as a permanent support platform.

[0072] S424: According to the three-dimensional measurement and verification data, if the deviation is greater than the allowable value, timely adjustment should be made. The adjustment measures are to cut some welding points, use a hand chain hoist to correct the position of the cableway pipe, and then measure and verify. After the verification requirements, weld the cut points and reinforce the welding;

[0073] S425: Take out the center positioner;

[0074] S426: Construct the main tower concrete, and then install the next section of the cableway pipe;

[0075] The cement is silicate cement, sulphoaluminate cement or slag cement; the sand is fine sand or medium sand; the diameter of the crushed stone is 5 to 40 mm; the temperature control methods during concrete pouring include: (1) using low-temperature water to rinse or spray the formwork before concrete pouring; (2) adding a cooling agent to the concrete during pouring; (3) adding ice cubes, ice water or distilled water to the concrete.

[0076] At the same time, when pouring the lower tower column and the upper tower column, it is necessary to hang a chute to assist in the pouring of materials. The chute is arranged at a spacing of 1.5m to 2m, and the falling height of the concrete does not exceed 2m; the concrete is cured by covering it with sacks or geotextiles and then sprinkling water to moisten it. The curing is carried out within 12 hours after the pouring is completed. The curing time of the lower tower column is not less than 24 days, and the curing time of each section of the upper tower column is not less than 7 days; the concrete is vibrated with an inserted vibrator, and the moving spacing of the vibrator does not exceed 1.5 times the effective radius of the vibrator, and the vibrator is kept at a distance of 50 to 100mm from the side form, and the vibration time is 25 to 35s.

[0077] In addition, the installation of the rigid frame in S13 is divided into two steps: (1) When the rigid frame is initially positioned on site, a short angle steel of the same type is welded to the inner side of the vertical angle steel at the top of the installed small-section truss in advance as the installation positioning code for the bottom of the extended truss. Then, the small-section truss is lifted by a lifting device and slowly approached to the installed truss so that the bottom of the vertical angle steel is close to the short angle steel used as the installation positioning code. The plane position, single-section inclination angle and top elevation of the installed truss are measured and adjusted according to the measurement results. When the truss position meets the requirements, the installation is completed. After the requirements are met, the lower end of the truss vertical angle steel is immediately welded to the short angle steel of the positioning code, and the initial positioning of the truss is completed; (2) The horizontal connection of the rigid frame is accurately positioned. After the small-section truss is extended and initially positioned, the horizontal connection angle steel is welded. First, the horizontal positioning angle steel is welded on the truss, and the horizontal position control point of the vertical main reinforcement of the lower tower column is marked on the horizontal positioning angle steel to determine the horizontal position edge line of the main reinforcement; then, the horizontal connection angle steel is installed and welded according to the horizontal position edge line of the main reinforcement, and horizontal bracing is added according to the length of the horizontal connection angle steel.

[0078] In addition, the steps of main reinforcement binding are as follows: after the rigid frame is installed, install the horizontal positioning angle steel on the rigid frame, and mark out the horizontal edge position control points of the inner and outer main reinforcements on the horizontal positioning angle steel; weld and connect the inner and outer connecting angle steels according to the control points on the horizontal positioning angle steel; mark out the spacing and position of the inner and outer main reinforcements on the connecting angle steel, extend and fix the inner and outer main reinforcements; the steps of horizontal reinforcement and chamfered reinforcement binding are as follows: after each row of main reinforcements is extended, start to bind the horizontal reinforcements, and first make a Mark the horizontal reinforcement, and then tie the horizontal reinforcement in a plum blossom shape. The reinforcement tying spacing should meet the design requirements, and the main reinforcement should be tied securely. After all the segmental horizontal reinforcements are tied, mark the horizontal reinforcement and main reinforcement according to the design position and inclination angle, and then tie the chamfered reinforcement and tie it securely with the horizontal reinforcement. The steps for tying the hook reinforcement are as follows: after the chamfered reinforcement is tied, set the hook reinforcement according to the intersection of the main reinforcement and the horizontal stirrups and tie it securely. The binding must be secure, and the hooks at both ends of the hook reinforcement must be hooked on the outside of the vertical main reinforcement and the horizontal annular reinforcement.

[0079] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A semi-floating cable-stayed bridge main tower construction process; characterized in that: The steps are as follows: S1: Lower tower column construction S11: Clean the construction site where concrete is to be poured, set up the support, material yard and pile positions, and measure the reference points according to the requirements of the design drawings; S12: Cement, sand, gravel and water are mixed into concrete by a mixer; S13: Define the pouring area, install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfer bars and hook bars. Then lay the formwork around the pouring area, fix the formwork support rods and bottom plate connectors, and make overall adjustments according to the design requirements. S14: Pump concrete from a pump truck and pour it into the formwork at a uniform speed, using one-time continuous pouring; S15: After the concrete is poured, vibrate and maintain; S2: Beam construction, bury the corbels in the tower body that has been poured at both ends of the upper beam, place the steel pipe column on the lower beam, and then lay the distribution beam and template on the corbels and the steel pipe column. The prestressing tension control of the beam, first of all, the installation and positioning of the plastic corrugated pipe, the corrugated pipe is positioned on the frame after the installation of the rigid frame, and fixed with steel bars at the joints. When tying the transverse stirrups of the main reinforcement to the corrugated pipe, tie the anti-collapse steel bars of the corrugated pipe at the same time. Secondly, when installing the anchor seat, first temporarily fix the anchor seats on the main reinforcement or stirrups one by one, and Connect the corrugated pipe and fix it to the notch template with bolts. To prevent the corrugated pipe from leaking, insert a rubber hose into the corrugated pipe after the anchor seat is installed and pull it out after the concrete is initially set. If the corrugated pipe is deformed, it should be handled immediately. Before tensioning, the bundles are threaded. Each bundle has dozens of strands, which are divided into several small bundles and threaded several times. Each small bundle is buried with a sparse handle and tied in one section. The manual threading method is adopted, and finally the prestressing is carried out. Due to the large tensioning tonnage and small curvature radius, in order to ensure that each steel strand is evenly stressed, it is tensioned in batches; S3: Construction of upper tower column S31: Install the rigid skeleton and steel bars. The installation of steel bars includes the binding of main bars, horizontal bars, chamfered bars and hook bars. Install the first section of the formwork and reinforce it. Use the same mix ratio of concrete as in S12 for pouring and curing. S32: Install the second section of the formwork, vibrate and cure after pouring, then roughen and turn the formwork up to pour the third section, then turn the formwork over again to complete the pouring of the second to last section, and finally pour the top layer, then vibrate and cure; S4: Construction of cableway pipe S41: Ground installation S411: Divide the rigidity of the rigid frame into sections, and use AutoCAD graphics software to perform theoretical analysis on each section, taking into account the weight of the cableway tube and the rigid frame, the lifting capacity of the tower crane, and the factors affecting the overall rigidity of the rigid frame; S412: Construction data collection, using AutoCAD graphics software to draw three-dimensional graphics and obtain the spatial coordinates and relative coordinates of each point; S413: According to the maximum width and length of the rigid frame, a ground installation platform is manufactured on site; S414: Make and install a center point locator, and find the center point of the space between the upper and lower ends of the cableway pipe through the center point locator; S415: The projection position of the outer edge line, center line, and center points of the upper and lower openings of the cableway pipe on the construction platform; S416: Install the rigid frame on the platform according to the platform's contour line and center line. Use a truck crane for installation and make adjustments through simple levers and manual work. S417: Install the cableway pipe. Determine the position of the cableway pipe according to the projection center point on the platform and the height between the center points of the upper and lower ends of the cableway pipe and the projection surface. Use a car crane to install it. Use a simple lever and manual adjustment. After the adjustment is completed, fix the cableway pipe on the frame. S418: Move the installed cableway pipe and the frame out of the installation platform using a truck crane; S419: Install the next section of the cableway pipe; S42: High altitude installation S421: Weld the positioning steel plate on the top surface of the rigid frame that has been installed at high altitude, and then check the top surface elevation. If the elevation deviation is large, make necessary adjustments by cutting or padding. On the positioning steel plate, lay out the outer edge of the frame to be installed; S422: Installation in place: Use a tower crane to hoist the cableway pipe and rigid frame installed on the ground and install them on the positioning plate on the top surface of the previous rigid frame. According to the positioning line on the positioning plate, the rigid frame is rigidly positioned and preliminarily welded. S423: Verify the coordinates of the center points of the upper and lower openings of the cableway pipe. The measurement adopts the forced centering three-dimensional measurement technology. The total station is used to measure the coordinates of the sharp point of the center point positioner. The total station observation platform is set as a permanent support platform. S424: According to the three-dimensional measurement and verification data, if the deviation is greater than the allowable value, timely adjustment should be made. The adjustment measures are to cut some welding points, use a hand chain hoist to correct the position of the cableway pipe, and then measure and verify. After the verification requirements, weld the cut points and reinforce the welding; S425: Take out the center positioner; S426: Construct the main tower concrete, and then install the next section of the cableway pipe.

2. The construction process of a main tower of a semi-floating cable-stayed bridge according to claim 1, characterized in that: The cement is silicate cement, sulphoaluminate cement or slag cement; the sand is fine sand or medium sand; the diameter of the crushed stone is 5 to 40 mm.

3. The construction process of the main tower of a semi-floating cable-stayed bridge according to claim 1 is characterized by: Temperature control methods during concrete pouring include: (1) using low-temperature water to rinse or spray the formwork before pouring concrete; (2) adding cooling agents to the concrete during pouring; (3) adding ice cubes, ice water or distilled water to the concrete.

4. The construction process of a main tower of a semi-floating cable-stayed bridge according to claim 1 is characterized by: When pouring the lower tower column and the upper tower column, it is necessary to hang a chute to assist in pouring. The chute is arranged at a spacing of 1.5m to 2m, and the falling height of the concrete does not exceed 2m.

5. The construction process of the main tower of a semi-floating cable-stayed bridge according to claim 1 is characterized by: Concrete curing is done by covering it with sacks or geotextiles and then sprinkling water on it to moisten it. Curing should be carried out within 12 hours after the pouring is completed. The curing time for the lower tower column is not less than 24 days, and the curing time for each section of the upper tower column is not less than 7 days.

6. The construction process of a main tower of a semi-floating cable-stayed bridge according to claim 1 is characterized by: The concrete is vibrated with an inserted vibrator. The moving distance of the vibrator shall not exceed 1.5 times the effective radius of the vibrator, and the vibrator shall be kept at a distance of 50 to 100 mm from the side form. The vibration time shall be 25 to 35 seconds.

7. The construction process of a main tower of a semi-floating cable-stayed bridge according to claim 1, characterized in that: The installation of the rigid frame in S13 is divided into two steps: (1) When the rigid frame is initially positioned on site, a short angle steel of the same type is welded to the inner side of the vertical angle steel at the top of the installed small-section truss in advance as the installation positioning code for the bottom of the extended truss. Then, the small-section truss is lifted by a lifting device and slowly approached to the installed truss so that the bottom of the vertical angle steel is close to the short angle steel used as the installation positioning code. The plane position, single-section inclination angle and top elevation of the installed truss are measured and adjusted according to the measurement results. When the truss position meets the requirements, the installation is completed. After the request is made, the lower end of the truss vertical angle steel is immediately welded to the short angle steel of the positioning code, and the initial positioning of the truss is completed; (2) The horizontal connection of the rigid frame is accurately positioned. After the small-section truss is extended and initially positioned, the horizontal connection angle steel is welded. First, the horizontal positioning angle steel is welded on the truss, and the horizontal position control point of the vertical main reinforcement of the lower tower column is marked out on the horizontal positioning angle steel to determine the horizontal position edge line of the main reinforcement; then, the horizontal connection angle steel is installed and welded according to the horizontal position edge line of the main reinforcement, and horizontal bracing is added according to the length of the horizontal connection angle steel.

8. The construction process of a main tower of a semi-floating cable-stayed bridge according to claim 1 is characterized by: The steps for binding the main reinforcement are as follows: after the rigid frame is installed, install the horizontal positioning angle steel on the rigid frame, and mark out the horizontal edge position control points of the inner and outer main reinforcements on the horizontal positioning angle steel; weld and connect the inner and outer connecting angle steels according to the control points on the horizontal positioning angle steel; mark out the spacing and position of the inner and outer main reinforcements on the connecting angle steel, and extend and fix the inner and outer main reinforcements.

9. The semi-floating cable-stayed bridge main tower construction process according to claim 1 is characterized by: The steps for tying horizontal reinforcement and chamfered reinforcement are as follows: after each row of main reinforcement is extended, start tying horizontal reinforcement. First, make horizontal reinforcement marks on the main reinforcement, and then tie the horizontal reinforcement in a plum blossom shape. The spacing between steel bar tying should meet the design requirements, and the main reinforcement must be tied securely. After all the segmental horizontal reinforcements are tied, mark the horizontal reinforcement and main reinforcement according to the design position and inclination angle, and then tie the chamfered reinforcement and tie it securely to the horizontal reinforcement.

10. The semi-floating cable-stayed bridge main tower construction process according to claim 1, characterized in that: The steps for tying the hook reinforcement are as follows: after the chamfer reinforcement is tied, the hook reinforcement is set and tied according to the intersection of the main reinforcement and the horizontal stirrups. The binding must be firm, and the hooks at both ends of the hook reinforcement must be hooked on the outside of the vertical main reinforcement and the horizontal annular reinforcement.