Construction method for upper tower column in large-dip-angle variable-cross-section ultrahigh cable tower

Abstract

The invention discloses a construction method of an upper tower column in a large-dip-angle variable-cross-section ultrahigh cable tower, a middle tower column and the upper tower column form an inverted Y shape, and the construction method comprises the steps that a starting section of the middle tower column is constructed through a formwork of a middle tower column creeping formwork, other standard sections are constructed through the creeping formwork, a bracket is erected at the intersection of the middle tower column, and an intersection section is constructed through a creeping formwork outer climbing frame; when the upper tower column is constructed, the support body is adjusted firstly, then the steel anchor beam is integrally installed, and then the upper tower column is constructed through the hydraulic creeping formwork. Smooth conversion construction of the joint of the lower tower column and the middle tower column is achieved by designing the lower tower column creeping formwork dismantling method and reasonably designing the construction procedures, the process improves the structural stability, operation is convenient, overall protection is complete, and construction safety is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering cable tower construction, and more specifically, to a construction method for a middle and upper tower column of a large-angle variable-section super-high cable tower. Background Art

[0002] With the development of China's society and economy, bridge construction has shown an unprecedented scale in the engineering field. In bridge engineering, the construction of the cable-stayed bridge across the Yellow River is a very important component. As a cable system, the cable-stayed bridge has a larger spanning capacity and a light structure. It not only saves materials but also has good economic efficiency. It has been widely used in the Yellow River Basin. The construction of the cable tower of the cable-stayed bridge is the top priority in the bridge construction process.

[0003] In recent years, in order to meet the requirements of urban landscape, the main tower structure should have a unique aesthetic sense compared with the previous linear structure. The most common requirement is to design it into a "diamond-shaped" main tower structure. Specifically, the lower tower column of the "diamond-shaped" main tower is a V-shaped structure with a large inclination angle and a variable cross-section, and the middle and upper tower columns are inverted Y-shaped. In the construction project, due to the large inclination angle, irregular cross-section, and large distribution of concrete deadweight, the formwork is also subject to a large load, which makes it difficult to fix. The linear control of the lower tower column with a large inclination angle of the cable tower is difficult. The shorter tower column is often constructed by the bracket method. The bracket system is used on the large-angle climbing surface to transfer the concrete load to the ground foundation through the bracket. The characteristics of this method are simple construction technology and obvious mechanical model. However, the bracket method is not suitable for riverside and middle and upper tower column construction. The bracket method has high construction cost, long construction period, and large engineering volume. Therefore, climbing formwork is generally used for construction. The hydraulic climbing formwork has good climbing stability, convenient operation, overall protection, and light frame, which greatly improves construction safety, can speed up construction progress, and reduce construction costs. For the construction of the middle and upper tower columns, after the construction of the lower tower column is completed, due to the large inclination angle between the lower tower column and the middle tower column, how to smoothly switch from the lower tower column to the middle tower column construction is also a technical challenge. In addition, the middle tower column is an inverted Y shape. How to carry out separate construction and smoothly achieve the top joint also requires technical improvements to adapt to the construction of the new tower column structure. Summary of the invention

[0004] One object of the present invention is to provide a construction method for the upper and middle tower columns of a large-angle variable-section super-high cable tower. By designing a method for removing the climbing formwork of the lower tower column and reasonably designing the construction process, the smooth conversion construction of the connection between the lower tower column and the middle tower column can be achieved. The process improves the structural stability, is easy to operate, and has perfect overall protection, which greatly improves construction safety.

[0005] In order to solve the above technical problems, the present invention provides a construction method for the middle and upper tower columns of a large-angle variable-section super-high cable tower. The middle tower column and the upper tower column are formed into an inverted Y shape, and the construction method comprises: the starting segment of the middle tower column is constructed using the template of the middle tower column climbing formwork, and the remaining standard segments are constructed using the climbing formwork. A bracket is set up at the intersection of the middle tower column, and the intersection section is constructed using a climbing frame outside the climbing formwork; when constructing the upper tower column, the bracket frame is adjusted first, and then the steel anchor beam is installed as a whole, and then the upper tower column is constructed by a hydraulic climbing formwork.

[0006] Preferably, a large inclination angle is formed between the first section of the middle tower column and the lower tower column. After the construction of the first section of the middle tower column is completed, the climbing formwork equipment of the lower tower column will be completely dismantled and the construction of the middle tower column will be transferred. The specific dismantling process is as follows: 1) After the first section of the middle and upper tower column is fully maintained, the upper truss of the hydraulic climbing formwork is removed by tower crane; 2) Use the first hand chain hoist to connect the middle part of the lower bracket of the hydraulic climbing formwork to the cable tower and remove the guide rail; 3) Use a tower crane and a safety sling to assist in the lifting of the hydraulic climbing formwork, where the upper end of the safety sling is fixed to the first section of the middle tower column; 4) Remove the lower climbing cone support and hydraulic oil pump; 5) Release the first hand chain hoist to set the length, remove the pin of the upper climbing cone support, and use the tower crane to lift the hydraulic climbing formwork to separate the hydraulic climbing formwork from the upper climbing cone support; 6) Use the tower crane to slowly move the hydraulic climbing formwork and slowly release the first hand winch to separate the hydraulic climbing formwork from the cable tower, remove the safety sling and the first hand winch, lower the hydraulic climbing formwork; and remove the upper climbing cone support.

[0007] Preferably, the construction of the middle tower column specifically includes: first constructing the lower cross beam, then symmetrically constructing the first segment tower column of the middle tower column on both sides, and removing the climbing formwork of the lower tower column, and then symmetrically constructing the segment tower columns in turn by the climbing formwork again until the horizontal cross brace position, installing the horizontal cross brace, and then repeating the above process to symmetrically construct the remaining tower columns in turn and install the horizontal cross brace, when the construction reaches the segment below the intersection, staggeredly constructing the tower columns on both sides of the next segment of the intersection, and finally constructing the intersection segment tower column to complete the construction of the middle tower column; The upper tower column construction specifically includes: first constructing the first section of the upper tower column, then adjusting the support frame, continuing the construction to the installation position of the steel anchor beam, installing the steel anchor beam, and then constructing the tower column through hydraulic climbing formwork in sequence until the upper tower column construction is completed.

[0008] Preferably, the rigid frames of the middle tower column and the upper tower column both adopt a truss structure, the rigid frames are divided into blocks, and then the divided rigid frames are processed into segments in the processing site. After being transported to the construction site, the segments are assembled to form an integral rigid frame block; initially, the foundation section steel is pre-embedded at the designed position, and after the construction of the upper layer of the pedestal is completed, the assembled rigid frame truss blocks are welded and installed on the pre-embedded foundation section steel. Before installation, they are temporarily fixed and then measured and positioned. After the positioning accuracy meets the design requirements, they are welded and fixed; this process is repeated, and the rigid frame truss blocks are installed in sequence. Adjacent frame blocks are welded into a whole using connecting angle steels as horizontal braces and diagonal braces.

[0009] Preferably, each section of the rigid frame is higher than the tower column concrete surface by a set height, serving as a connecting section for the next section of the rigid frame; when the rigid frame conflicts with the tower column structural member, the accurate positioning of the structural member is first ensured.

[0010] Preferably, the steel anchor beam is installed synchronously with the construction of the cable tower column segment. The steel anchor beam installation positioning method uses a total station to measure each structural feature point to obtain high-precision size and elevation data, and then accurately compares it with the design value and adjusts it to the error requirement range, specifically including: First, the four corner points on the top surface of the anchor box bottom plate are used as known points to set up the measurement station. Before setting up the station, the steel anchor beam is accurately leveled so that the height difference of the four corners is within the set height difference range. Secondly, after the station is successfully set up, a vertical prism is set at the anchor point to measure the center position of the anchor point; Next, a steel plate is set at the lower end of the cable duct axis and fixed, and the cable duct axis point corresponding to this elevation is placed on the steel plate, and then a pull line is set between this point and the center of the anchor point, which is the cable duct axis; Then, measure the distance from the inner wall of the cable guide tube to the pulling axis in four 90-degree directions, and adjust the position of the cable guide tube until the deviation value is qualified; Finally, the cable duct is fixed. The cable duct has been cut and matched according to the design data before installation on site. When the axis deviation is qualified, the mileage direction error is within the error requirement range.

[0011] Preferably, the steel anchor beam is installed on the tower. After the total station is set up, when the setting error exceeds the set value, the mileage and elevation corrections are performed using the backsight point set at the crossbeam in the tower to ensure that the relative error of each section of the steel anchor beam is within the qualified range when it is installed. The specific method is: first, measure the positions and elevation data of the centers of the four anchor points and the four corner points of the top plate. If the error exceeds the value required by the specification, make adjustments; secondly, jacks are set at the design positions of the four corners of the previous section of the steel anchor beam, and the spatial positions of the characteristic points of the steel anchor beam of the installation section are adjusted by adjusting the elevations of the four corners until the data is qualified; finally, after positioning is completed, the limit device is fixed, and the position of the cable guide axis is again staked out on the steel plate set up during site acceptance. When the error exceeds the specification, the position of the cable guide is fine-tuned until the data is qualified and fixed.

[0012] The present invention has at least the following beneficial effects: 1. The present invention ensures the safety of installation and disassembly of large-angle formwork frames by accurately controlling the inclination angle and cross-sectional changes of the formwork; the stable installation and precise positioning of the rigid skeleton provide a strong support system for the cable tower; the accurate installation and positioning of the steel anchor beam further enhances the overall stability of the structure. The process improves structural stability, is easy to operate, and has perfect overall protection, greatly improving construction safety. The construction method of the present invention is simple, economical, and widely applicable. It has considerable reference value in the field of similar engineering construction and provides important technical guarantees for the construction of the main tower of the cable-stayed bridge.

[0013] 2. The installation and dismantling construction method of the large-angle variable-section super-high cable tower climbing surface formwork of the present invention is stable and easy to operate, ensuring a smooth transition of the formwork during the dismantling process and avoiding safety risks caused by improper operation.

[0014] 3. The rigid frame installation and positioning method of the present invention can improve the positioning accuracy of the rigid frame without increasing the difficulty of construction, reduce the adverse effects caused by construction errors, effectively control the construction quality and reduce rework costs.

[0015] 4. The steel anchor beam installation and positioning method of the present invention uses a total station to measure each structural feature point, which can obtain high-precision size and elevation data, and accurately compare with the design value to ensure that the installation position of the steel anchor beam is accurate. During the installation of the steel anchor beam, the spatial position of the steel anchor beam can be fine-tuned by setting a jack and adjusting the elevation of the four corners to ensure the accurate positioning of each feature point. This improves construction accuracy, ensures construction quality, improves construction efficiency, reduces safety risks, facilitates quality control, and enhances structural stability.

[0016] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the tower column structure in the present invention; Figure 2 This is a structural schematic diagram of step 1 of tower column construction in the present invention; Figure 3 This is a structural schematic diagram of the second step of tower column construction in the present invention; Figure 4 This is a structural schematic diagram of step three of tower column construction in the present invention; Figure 5 This is a structural schematic diagram of step five of tower column construction in the present invention; Figure 6 It is a schematic diagram of the construction platform structure of the starting section of the tower column in the present invention; Figure 7 It is the elevation layout diagram of the rigid skeleton of the upper tower column in the present invention; Figure 8 This is a schematic diagram of the construction platform of the bracket for the tower column intersection section in the present invention; Fig. 9 This is a schematic diagram of the first step of dismantling the large-angle hydraulic climbing formwork of the present invention; Fig.10 This is a schematic diagram of the second step of dismantling the large-angle hydraulic climbing formwork of the present invention; Fig.11 This is a schematic diagram of step three of dismantling a large-angle hydraulic climbing formwork according to the present invention; Fig.12 This is a schematic diagram of step 4 of dismantling a large-angle hydraulic climbing formwork according to the present invention; Fig.13 This is a schematic diagram of step five of dismantling the large-angle hydraulic climbing formwork of the present invention. DETAILED DESCRIPTION

[0018] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement it according to the description.

[0019] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] 1. Construction of middle tower column.

[0021] The middle tower column is a double-tower-limb structure, and the single tower limb adopts a single-box single-chamber section with a cross-sectional size of 3.5m×6.0m (transverse bridge direction×longitudinal bridge direction), the transverse bridge wall thickness is 80cm~100cm, and the longitudinal bridge wall thickness is 80cm~90cm.

[0022] The middle tower column is 42.185m high and is divided into 11 sections along the height direction (section 20 to section 30). Section 20 is the starting section of the middle tower column, section 21 is the climbing formwork installation section, sections 22 to 28 are standard sections (climbing formwork construction), and sections 29 to 30 are intersection sections. The structure of the middle tower column is as follows: Figure 1 shown.

[0023] 1. Construction process of middle tower column.

[0024] The starting section of the middle tower column is constructed using the formwork of the middle tower column climbing formwork. The climbing formwork is installed on the starting section, and the standard sections are constructed using the climbing formwork. A bracket is set up at the intersection of the tower columns, and the intersection section is constructed using the climbing frame outside the climbing formwork.

[0025] Construction of lower crossbeam - installation of reinforcement for the 20th segment tower column, including erection of construction platform and reinforcement processing - installation of formwork for the 20th segment tower column - pouring of concrete for the 20th segment tower column, including removal of lower tower column formwork - installation of climbing formwork on the 20th segment - construction of 21st to 25th segment tower columns with climbing formwork - climbing the climbing formwork to the 25th segment tower column - installation of the first horizontal cross brace for the middle tower column - construction of 25th to 26th segment tower columns with climbing formwork - climbing the climbing formwork to the 27th segment tower column - installation of the second horizontal cross brace for the middle tower column - construction of 27th segment tower column with climbing formwork - staggered construction of 28th segment tower column - removal of the cross bridge and climbing frame to the inside - installation of intersection bracket and bottom formwork - removal of the remaining climbing formwork to the inside of the cross bridge - installation of the third horizontal cross brace for the middle tower column - construction of 29th to 30th segment tower columns - completion of middle tower column construction.

[0026] 2. Construction steps of middle tower column.

[0027] Step 1: First, use the 19th segment frame as a construction platform to construct the 20th segment (the first section of the middle tower column) reinforcement. Figure 2 As shown in the figure), the longitudinal climbing frame of the bridge is removed, two hanging frames are hung on the 19th section, and the concrete of the tower column of the 20th section is poured in the mold.

[0028] Step 2: If Figure 3 As shown, first, the lower tower column climbing formwork is removed for modification, and the climbing formwork is installed again on the 20th segment. Secondly, the 21st segment tower column reinforcement is installed, and the 21st segment tower column concrete is poured in the mold.

[0029] Step 3: If Figure 4 As shown, first, the QTZ900 tower crane installs the first layer of attachment, and then lifts up to 5 standard sections; the WA7015-10E tower crane installs the second layer of attachment, and then lifts up to 8 standard sections. Secondly, the 22nd to 25th section templates and frames climb normally, the climbing formwork climbs to the 25th section, and the first horizontal cross brace of the middle tower column is installed. Then, the elevator is raised to the first horizontal cross brace.

[0030] Step 4: First, the 26th to 27th section formwork and frame are normally climbed, the climbing formwork is climbed to the 27th section, and the second horizontal cross brace of the middle tower column is installed. Secondly, the elevator is raised to the second horizontal cross brace.

[0031] Step 5: If Figure 5 As shown, firstly, due to insufficient spacing before the intersection section, the two tower columns of the 28th section were staggered by one section for construction. Secondly, the bracket bracket embedded parts of the middle tower column intersection section were pre-embedded during the construction of the 28th section.

[0032] Step 6: First, install the WA7015-10E tower crane on the third layer, and then lift it to the height of one standard section. Secondly, remove the upper frame of the climbing formwork on the inner side of the cross bridge of the 28th section, and install the bracket and bottom formwork of the intersection section on the 28th section. Then, remove the remaining climbing formwork on the inner side of the cross bridge of the 28th section, and install the third horizontal cross brace of the middle tower column. Again, raise the elevator to the 29th section. Finally, install the steel bars of the tower column of the 29th section, climb the climbing formwork to the 29th section, and pour the concrete of the tower column of the 29th section.

[0033] Step 7: First, QTZ900 tower crane installs the second layer of attachment, and then lifts 5 standard sections; WA7015-10E tower crane lifts 8 standard sections. Secondly, the elevator is connected to the 30th section. Then, the 30th section tower column reinforcement is installed. Finally, the formwork and frame climb normally, the 30th section tower column concrete is cast, and the construction of the middle tower column is completed.

[0034] 3. Specific construction technology of the middle tower column.

[0035] (1) Construction of the starting section of the middle tower column (section 20).

[0036] A. Construction platform.

[0037] The construction platform of the starting section of the middle tower column is divided into two parts: Figure 6 As shown, the lower tower column climbing formwork is used as a construction platform for the outer part of the tower column, and a scaffolding platform is set up on the lower crossbeam for the inner part of the lower crossbeam.

[0038] After the construction of the lower beam is completed, continue to climb the climbing formwork until it is flush with the corner line of the tower column. At this time, the hydraulic climbing formwork can be used as the construction platform for the 20th section to complete the work of steel bar binding and formwork installation. In the area above the lower beam, a scaffolding platform can be set up on the lower beam. The scaffolding platform is set up with a fastener-type bracket. The platform can be set up on site according to the external dimensions of the tower column to ensure that all parts have continuous and stable operating space during the construction process.

[0039] B. Rigid skeleton.

[0040] The steel reinforcement frame of the middle tower column adopts a truss structure and is connected to the lower tower column. The entire reinforcement frame is divided into 21 segments, using a 2m high standard segment. Figure 7 The figure shows the elevation layout of the rigid skeleton of the upper tower column in the present invention.

[0041] To facilitate transportation, on-site positioning and installation, the rigid frame is formed into truss blocks on each side. These blocks are processed into segments in the processing site and then transported to the site and assembled in segments to form the rigid frame as a whole.

[0042] The starting section and intersection section of the middle tower column are non-standard sections. The height of the rigid frame is determined according to the corresponding concrete pouring height. The height of each section is controlled to be 1m higher than the corresponding concrete pouring surface, and the higher part is used as the starting section for the subsequent rigid frame installation.

[0043] When installing the rigid frame, first temporarily fix it, measure and position it, and then weld and fix the rigid frame blocks after the accuracy meets the requirements. Use connecting angle steels as horizontal and diagonal braces between adjacent frame blocks and weld them into a whole.

[0044] The tower column steel reinforcement frame adopts a truss structure. The installation steps are as follows: 1) Before constructing the first layer of cap concrete, pre-embed the foundation section steel of the rigid skeleton at the corresponding position. The foundation section is a steel bar, and the top of the bar is controlled by the design bottom elevation of the skeleton.

[0045] 2) After the construction of the second-layer foundation is completed, the processed rigid skeleton truss blocks will be hoisted and welded to the embedded foundation nodes.

[0046] 3) The rigid skeleton blocks are hoisted by crawler cranes for foundation construction. They are temporarily fixed during installation. After measurement and positioning, the rigid skeleton blocks are welded and fixed after the accuracy meets the requirements. Adjacent skeleton blocks are welded into a whole using connecting angle steels as horizontal and diagonal braces.

[0047] The following points should be noted when installing and positioning: 1) Each section of the rigid frame should be 1m higher than the concrete surface of the tower column, serving as the connection section of the next section of the rigid frame.

[0048] 2) The surveying personnel first weld the limiting angle steel on the embedded truss connecting plate according to the tower column taper angle.

[0049] 3) The crawler crane hoists the truss. When the diagonal columns of the truss enter the limit devices on the connecting plate, the surveyors will check whether the tilting position meets the requirements. When it meets the design requirements, the frame and the connecting plate will be welded immediately.

[0050] 4) When each truss is hoisted, it is necessary to set up guy ropes for preliminary fixation to prevent it from hitting the steel bars and other components.

[0051] 5) Each upright of the rigid frame should be numbered in detail. During the installation process, each upright should be welded according to the corresponding number. During the welding process, the positioning should be accurately adjusted through measurement to ensure that the frame size and axis are installed accurately.

[0052] 6) If the rigid frame conflicts with the position of the tower column structure, first ensure the accurate positioning of the structure.

[0053] The above-mentioned rigid frame installation and positioning method can improve the positioning accuracy of the rigid frame without increasing the difficulty of construction, reduce the adverse effects caused by construction errors, effectively control the construction quality and reduce rework costs.

[0054] (2) Construction of climbing formwork installation section (section 21).

[0055] When constructing the 20th section tower column, the anchoring structure of the climbing frame is pre-buried on the tower column. The anchoring structure adopts a climbing cone. After the construction of the 20th section is completed, the climbing frame of the climbing formwork is installed on the 20th section tower column. The climbing frame is used as a construction platform for the 21st section tower column and a platform for the construction of the rigid frame, steel bars, formwork and other engineering projects of the 21st section tower column.

[0056] In the area above the lower crossbeam, a scaffolding platform can be set up on the lower crossbeam. The scaffolding platform is set up with a fastener-type bracket. The setting up of the platform can be determined on-site according to the external dimensions of the tower column to ensure that all parts have continuous and stable operating space during the construction process.

[0057] (3) Construction of sections 22 to 28 of the middle tower column.

[0058] As the middle tower column rises, the tower limbs tilt inward as a whole, and the tower column generates a horizontal inward force. In order to offset the inward force of the middle tower column and achieve the goal of controlling the line shape and stress of the tower column, three horizontal cross braces are set on the middle tower column, with a spacing of 8m between each cross brace. The concrete pouring of the 24th segment tower column is completed. After the tower column concrete reaches the strength, the hydraulic climbing formwork climbs to the 25th segment tower column and installs the first horizontal cross brace of the middle tower column. The concrete pouring of the 26th segment tower column is completed. After the tower column concrete reaches the strength, the hydraulic climbing formwork climbs to the 27th segment tower column and installs the second horizontal cross brace of the middle tower column. The concrete pouring of the 28th segment tower column is completed. After the tower column concrete reaches the strength, the cross bridge is removed and the inward climbing formwork is installed, and the third horizontal cross brace of the middle tower column is installed.

[0059] (4) Construction of the middle tower column intersection section (sections 29 to 30).

[0060] The 29th section of the middle tower column is the intersection section of the two tower columns. This section of the tower column is 3.248m high. The 30th section above is the intersection section of the middle tower column. The intersection section is constructed with brackets. When constructing the 28th section of the tower column, the bracket embedded parts are embedded on the tower column. The brackets are arranged from bottom to top: double-joined 50a corbels, double-joined 40a unloading blocks, 25a arch frames, 20a distribution beams, and bottom formwork. After the concrete pouring of the 28th section of the tower column is completed, the cross bridge is removed and the trusses on the inner climbing formwork are used. The main load-bearing layer of the climbing formwork is used as the construction platform for installing the bracket of the intersection section. Figure 8 The figure shows a schematic diagram of the bracket construction platform of the intersection section.

[0061] 4. After the construction of the 20th section of the tower column is completed, the climbing formwork equipment will be completely dismantled and the construction of the middle tower column will begin. The specific dismantling process is as follows: (1) If Fig. 9 As shown in the figure, after the first section of the middle and upper tower column is cured, the upper truss of the hydraulic climbing formwork is removed by using a tower crane. The high-angle climbing frame is lifted, and after pouring the concrete of the 20th section, the inclined steel formwork is removed after curing, and the climbing formwork bracket on the downward climbing surface is ready to be removed.

[0062] (2) If Fig.10 As shown, the first hand chain hoist is used to connect the middle part of the lower bracket of the hydraulic climbing formwork to the cable tower, and the guide rail is removed. The hydraulic climbing formwork system and hand chain hoist are used to push out the climbing formwork track, and the tower crane is used to lift and remove it.

[0063] (3) If Fig.11 As shown, the hydraulic climbing formwork is assisted in lifting using a tower crane and a safety sling, wherein the upper end of the safety sling is fixed to the first section of the middle and upper tower column. Preparation for dismantling the climbing formwork support.

[0064] The tower crane is installed at the fulcrum of the main platform load-bearing frame at 4 points, and plays the main vertical force role; Use two 6m long slings (load-bearing 5t) with the upper ends fixed on the main reinforcement and rigid frame, and the lower ends fixed on the supporting points of the load-bearing frame inside the main platform to play a limiting role; Two ear plates (using 2.5 cm thick steel plates) are welded on the embedded steel plate of the 0# bracket to fix two 5t hand hoists. The lower part is connected in series with steel wire ropes, and the lower end is fixed at the fulcrum position of the load-bearing frame on the inner side of the main platform to play a limiting role.

[0065] Clear away small items on the climbing formwork hanger, and remove large items such as hydraulic oil pumps, distribution boxes, etc. from the main platform springboard and hoist them away with the tower crane. Also, weld and fix the parts on the platform that are easy to fall off to ensure that no items fall off during the lifting process.

[0066] (4) If Fig.12 As shown, remove the lower climbing cone support and the hydraulic oil pump; release the first hand chain hoist to a certain length, remove the pin of the upper climbing cone support, and use the tower crane to lift the hydraulic climbing formwork to separate the hydraulic climbing formwork from the upper climbing cone support. After the preliminary work is in place, the operator uses the intercom to command the removal of the climbing cone support. Before removal, ensure that all hoisting and limiters are fully stressed and no large sliding occurs.

[0067] (5) If Fig.13 As shown, use the tower crane to slowly move the hydraulic climbing formwork, and slowly release the first hand chain hoist to separate the hydraulic climbing formwork from the cable tower, release the safety sling and the first hand chain hoist, and lower the hydraulic climbing formwork. The operator uses the intercom to give unified commands, and through the hand chain hoist, the two sides synchronously and slowly release the wires to free the climbing formwork hanger from the restraints, while preventing the frame from swinging sharply; when the climbing frame is completely out of contact with the tower body, unfasten the upper part of the safety sling at the top of the 20th segment, loosen the connection between the hand chain hoists on both sides and the wire rope, release the limit and slowly lower it, and pull the cable wind rope at the bottom of the hanger during the lowering process. (The maximum possible travel of the hand chain hoist is about 1.7m).

[0068] (6) Remove the climbing cone support.

[0069] In the above dismantling step diagram, the climbing formwork track climbing cone 1, the elevator platform embedded 2, the 0# block embedded parts 3, the tower crane supporting wall embedded 4, and the cable wind rope 5 are shown.

[0070] During the construction process of the above-mentioned large-angle variable-section cable tower column, the installation and dismantling construction method of the climbing surface formwork of the large-angle variable-section super-high cable tower is stable and easy to operate, ensuring a smooth transition of the formwork during the dismantling process and avoiding safety risks caused by improper operation.

[0071] 2. Construction of upper tower column.

[0072] The cross section of the upper tower column is an octagonal box section with a width of 5.5m in the transverse direction and 6.0m in the longitudinal direction. The thickness of the tower body in the transverse and longitudinal directions is 0.7m, and the total height of the tower column is 35m. It is divided into 8 sections from the 31st section to the 38th section. The 31st to 37th sections of the upper tower column are equipped with steel anchor beams, and 10 sets of upper tower columns are arranged on a single main tower.

[0073] 1. Construction process. Construction of the 30th section - adjustment of the support frame. When constructing the 31st section, the cross bridge climbing frame is re-hung with the help of a tower crane. When constructing the 32nd section, the longitudinal climbing frame is re-hung with the help of a tower crane - measurement and layout - construction joint treatment - overall installation of steel anchor beams, steel brackets, rigid embedded steel plates and cable guide tubes, and installation after overall pre-assembly - installation of steel bars and rigid skeletons, before which the rigid skeletons and steel bars are made, and embedded bars are installed in advance - formwork installation - concrete pouring and maintenance - hydraulic climbing formwork climbing - standard section construction of sections 33-38, during which the tower crane and elevator are synchronously connected - completion of upper tower column construction.

[0074] 2. Construction steps.

[0075] Step 1: Construction of Section 31.

[0076] First, the steel bars are installed and the embedded parts are installed simultaneously.

[0077] Secondly, after the construction of the 30th section is completed, the angle of the truss on the outer climbing frame along the bridge is straightened and climbed, and the cross-bridge climbing frame is re-hanged with the assistance of a tower crane, and the concrete of the 31st section is poured in the mold.

[0078] Step 2: Construction of sections 32 to 38.

[0079] First, install the steel bars and embedded parts; Secondly, after the construction of the 31st section is completed, the outer climbing frame along the bridge is re-hung with the assistance of a tower crane, the horizontal bridge climbing frame is normally climbed, and the concrete of the 32nd section is poured in the mold; Again, the 33rd to 38th sections were climbed normally and the upper tower column construction was completed; Finally, steel anchor beams are arranged in sections 31-37 of the upper tower column. The steel anchor beams and corbels are installed as a whole using a QTZ900 tower crane. The installation of the steel anchor beams is carried out alternately with the concrete pouring of the corresponding section tower columns.

[0080] 3. Construction technology.

[0081] 3. Positioning and installation of steel anchor beam.

[0082] After the steel anchor beam, steel bracket, tower wall steel plate and shear nail are manufactured and welded in the factory, they are transported to the site for overall assembly. The pre-assembly accuracy is checked and then hoisted and positioned by a large tower crane. The QTZ900 tower crane is used to install the steel anchor beam of the main tower. The whole piece hoisting method is adopted according to the performance parameters of the tower crane. The construction personnel tie the traction rope to one end of the steel anchor beam. During the lowering of the steel anchor beam, the rope operator directs the construction personnel to tighten the other end of the traction rope to cooperate with the tower crane to control the direction of the steel anchor beam to slowly descend to prevent collision with the installed steel anchor beam. After it is basically in place, the plane position is fine-tuned by the hand winch, and the installation accuracy is ensured by repeated measurement-adjustment-measurement. It is firmly fixed by steel to prevent displacement during concrete pouring. Considering the influence of shrinkage creep and compression of the main tower, the steel anchor beam is pre-lifted according to the monitoring instructions when installing the steel anchor beam on site. The steel anchor beam is installed in a synchronous installation manner with the construction of the cable tower column segment.

[0083] During the site acceptance of the steel anchor beam, a total station is used to measure the characteristic points of each structure, calculate the relative size and elevation position of each component, and compare them with the design value. The specific method is as follows: (1) Take the four corner points on the top surface of the anchor box bottom plate as known points for high-rise station. Before setting up the station, the steel anchor beam on the horse stool must be precisely leveled. The height difference of the four corners shall not be greater than 1mm, and the error of the side center on both sides of the four corners shall not exceed 2mm.

[0084] (2) After the station is successfully set up, a steel disc of corresponding size is set at the anchor point. A small hole with a diameter of 2 mm is set in the center of the disc to facilitate the erection of a prism to measure the center position of the anchor point.

[0085] (3) A 10cm*10cm steel plate is set at the lower end of the cable duct axis and fixed with angle steel support. The cable duct axis point corresponding to this elevation is placed on the steel plate.

[0086] (4) A pull line is then set between this point and the center of the anchor point, which is the axis of the cable guide.

[0087] (5) Use a short L ruler to measure the distance from the inner wall of the tube to the pulling axis in four 90-degree directions, and adjust the position of the cable guide tube until the deviation value is acceptable.

[0088] (6) The cable guide tube is then fixed with angle steel welding. The cable guide tube has been cut and matched according to the design data before installation on site. When the axis deviation is qualified, the mileage direction error is within the error requirement range.

[0089] Installation on the steel anchor beam tower should be carried out two hours after sunset at night. After the total station is set up, if the station setting error exceeds 3mm, the backsight point set at the crossbeam in the tower is used to correct the mileage and elevation to ensure that the relative error of each section of the steel anchor beam is within the qualified range during installation. The specific method is as follows: (1) When installing on the tower, the main measurements are the centers of the four anchor points and the positions and elevation data of the four corner points of the top plate.

[0090] (2) When the error exceeds the specified value, adjustments should be made.

[0091] (3) Jacks are installed near the four corners of the top of the previous section of the steel anchor beam. The spatial positions of the characteristic points of the steel anchor beam of the installation section are adjusted by adjusting the elevation of the four corners until the data is qualified.

[0092] (4) After positioning, weld the code plate and other limiting devices in time.

[0093] (5) After the limit is set, the cable guide axis position is again set on the 10cm*10cm steel plate set during site acceptance. If the error exceeds the specification requirements, the cable guide position needs to be fine-tuned until the data is qualified and fixed.

[0094] The above-mentioned steel anchor beam installation and positioning method uses a total station to measure each structural feature point, which can obtain high-precision size and elevation data, and accurately compare with the design value to ensure that the installation position of the steel anchor beam is accurate. During the installation of the steel anchor beam, the spatial position of the steel anchor beam can be fine-tuned by setting the jack and adjusting the elevation of the four corners to ensure the accurate positioning of each feature point. It improves construction accuracy, ensures construction quality, improves construction efficiency, reduces safety risks, facilitates quality control, and enhances structural stability.

[0095] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation mode, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, other modifications can be easily implemented, so without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A construction method for the upper tower column of a large-angle variable-section super-high cable tower, characterized in that: The middle tower column and the upper tower column are formed into an inverted Y shape, and the construction method includes: The starting section of the middle tower column is constructed using the formwork of the middle tower column climbing formwork, and the remaining standard sections are constructed using climbing formwork. Brackets are set up at the intersection of the middle tower columns, and the intersection section is constructed using the climbing frame outside the climbing formwork; When constructing the upper tower column, first adjust the support frame, then install the steel anchor beam as a whole, and then construct the upper tower column through hydraulic climbing formwork.

2. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 1 is characterized in that: A large inclination angle is formed between the first section of the middle tower column and the lower tower column. After the construction of the first section of the middle tower column is completed, the climbing formwork equipment of the lower tower column will be completely dismantled and the construction of the middle tower column will be transferred. The specific dismantling process is as follows: 1) After the first section of the middle and upper tower column is fully maintained, the upper truss of the hydraulic climbing formwork is removed by tower crane; 2) Use the first hand chain hoist to connect the middle part of the lower bracket of the hydraulic climbing formwork to the cable tower and remove the guide rail; 3) Use a tower crane and a safety sling to assist in the lifting of the hydraulic climbing formwork, where the upper end of the safety sling is fixed to the first section of the middle tower column; 4) Remove the lower climbing cone support and hydraulic oil pump; 5) Release the first hand chain hoist to set the length, remove the pin of the upper climbing cone support, and use the tower crane to lift the hydraulic climbing formwork to separate the hydraulic climbing formwork from the upper climbing cone support; 6) Use the tower crane to slowly move the hydraulic climbing formwork and slowly release the first hand winch to separate the hydraulic climbing formwork from the cable tower, release the safety sling and the first hand winch, lower the hydraulic climbing formwork; and remove the upper climbing cone support.

3. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 1 is characterized in that: The construction of the middle tower column specifically includes: first construct the lower cross beam, then symmetrically construct the first segment of the middle tower column on both sides, and remove the climbing formwork of the lower tower column, and then use the climbing formwork to symmetrically construct the segment tower columns in turn until the horizontal cross brace position, install the horizontal cross brace, and then repeat the above process to symmetrically construct the remaining tower columns in turn and install the horizontal cross brace. When the construction reaches the segment below the intersection, the tower columns on both sides of the next segment of the intersection are staggered, and finally the tower columns of the intersection segment are constructed to complete the construction of the middle tower column; The upper tower column construction specifically includes: first constructing the first section of the upper tower column, then adjusting the support frame, continuing the construction to the installation position of the steel anchor beam, installing the steel anchor beam, and then constructing the tower column through hydraulic climbing formwork in sequence until the upper tower column construction is completed.

4. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 1 is characterized in that: The rigid frames of the middle tower column and the upper tower column both adopt a truss structure. The rigid frames are divided into blocks, and then the divided rigid frames are processed into segments in the processing site. After being transported to the construction site, the segments are assembled to form an integral rigid frame block. Initially, the foundation section steel is pre-embedded at the designed position. After the construction of the upper pedestal is completed, the assembled rigid frame truss blocks are welded and installed on the pre-embedded foundation section steel. Before installation, they are temporarily fixed and then measured and positioned. After the positioning accuracy meets the design requirements, they are welded and fixed. Repeat this process, install the rigid frame truss blocks in sequence, and use connecting angle steels as horizontal braces and diagonal braces between adjacent frame blocks to weld them into a whole.

5. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 1 is characterized in that: Each section of the rigid frame is higher than the concrete surface of the tower column by a set height, serving as the connecting section of the next section of the rigid frame; when the position of the rigid frame conflicts with the tower column structural members, the accurate positioning of the structural members must be ensured first.

6. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 3 is characterized in that: The steel anchor beam is installed synchronously with the construction of the cable tower column segment. The steel anchor beam installation positioning method uses a total station to measure the characteristic points of each structure, obtain high-precision size and elevation data, and accurately compare them with the design values ​​before adjusting them to the error requirement range, including: First, the four corner points on the top surface of the anchor box bottom plate are used as known points to set up the measurement station. Before setting up the station, the steel anchor beam is accurately leveled so that the height difference of the four corners is within the set height difference range. Secondly, after the station is successfully set up, a vertical prism is set at the anchor point to measure the center position of the anchor point; Next, a steel plate is set at the lower end of the cable duct axis and fixed, and the cable duct axis point corresponding to this elevation is placed on the steel plate, and then a pull line is set between this point and the center of the anchor point, which is the cable duct axis; Then, measure the distance from the inner wall of the cable guide tube to the pulling axis in four 90-degree directions, and adjust the position of the cable guide tube until the deviation value is qualified; Finally, the cable duct is fixed. The cable duct has been cut and matched according to the design data before installation on site. When the axis deviation is qualified, the mileage direction error is within the error requirement range.

7. The construction method of the upper tower column of the large-angle variable-section super-high cable tower according to claim 6 is characterized in that: The steel anchor beam is installed on the tower. After the total station is set up, when the setting error exceeds the set value, the mileage and elevation correction is performed using the backsight point set at the crossbeam in the tower to ensure that the relative error of each section of the steel anchor beam is within the qualified range when it is installed. The specific method is: first, measure the positions and elevation data of the centers of the four anchor points and the four corner points of the top plate. If the error exceeds the value required by the specification, make adjustments; secondly, jacks are set at the design positions of the four corners of the previous section of the steel anchor beam, and the spatial positions of the characteristic points of the steel anchor beam of the installation section are adjusted by adjusting the elevations of the four corners until the data is qualified; finally, after the positioning is completed, the limit device is fixed, and the position of the cable guide axis is again staked out on the steel plate set up during the site acceptance. When the error exceeds the specification, the position of the cable guide is fine-tuned until the data is qualified and fixed.

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