A method for positioning and constructing the steel anchor box of a circular arch main tower of a cable-stayed bridge

Abstract

The present invention provides a method for positioning and constructing a steel anchor box for a circular arch main tower of a cable-stayed bridge, comprising the following steps: S1, measuring the axial alignment and verticality of the main tower and determining the installation time period of the steel anchor box; S2, determining the installation positioning points of the segmental steel anchor box and laying them out; S3, re-measuring the installation positioning points determined in S2 and installing the segmental steel anchor box; S4, determining the cable guide anchor point and the cable guide outlet position point on the segmental steel anchor box, and setting the cable guide outlet IP layout mark point; S5, re-measuring the cable guide outlet IP layout mark point and installing the cable guide pre-embedded section; S6, installing a template on the main tower wall, connecting a cable guide transition connecting steel plate at the end of the cable guide pre-embedded section, and connecting the cable guide rear connecting section to the cable guide transition connecting steel plate; S7, repeating steps S2-S6. The present invention has the effect of improving the existing problems in the installation of steel anchor boxes in the main tower, such as the difficulty in positioning, the inaccurate installation, the box construction period, and the construction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and in particular to a positioning construction method for a steel anchor box of a circular arch main tower of a cable-stayed bridge. Background Art

[0002] Cable-stayed bridges, a common type of long-span bridge, are increasingly being used in numerous bridge construction projects both domestically and internationally due to their uniquely beautiful main tower structure, relatively light weight, and material-saving features. A cable-stayed bridge uses multiple cables to directly tie the main beam to the tower. The structure is composed of compression-bearing towers, tension-bearing cables, and a bending-bearing beam. Cable-stayed bridges primarily consist of towers, main beams, and stay cables. During installation, a steel anchor box is installed within the tower, and one end of the cable guide is fixedly connected to the anchor box.

[0003] Currently, steel anchor boxes installed in cable-stayed bridge towers are usually manufactured in factories and then installed on-site in sections. This installation method has disadvantages such as difficult-to-control processing errors and cumulative installation errors, which are mainly manifested in the following aspects:

[0004] 1. Before installing the steel anchor box, its installation point needs to be observed and placed. However, due to the influence of the sway of the bridge tower, wind speed, weather and temperature, the initial positioning and precise positioning of the steel anchor box installation are both difficult, resulting in a long installation period.

[0005] 2. In the existing technology, the construction of the arched tower column adopts the hydraulic climbing formwork construction process. However, due to the inconsistency of the spatial coordinates of the cable guide tube of each section of the steel anchor box, and the fact that one end of the cable guide tube connected to the steel anchor box is tilted downward and extends 100 mm (the shortest position distance) from the tower column surface, the climbing formwork of each section needs to be adaptively modified, which increases the construction difficulty, prolongs the construction period, increases the construction cost, and makes it difficult to ensure the construction quality. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a positioning construction method for the steel anchor box of the circular arch main tower of a cable-stayed bridge, which can improve the problems of the existing technology in which the positioning of the steel anchor box in the main tower is difficult, resulting in inaccurate installation, and the problems of box construction period and construction cost.

[0007] According to an embodiment of the present invention, a method for positioning and constructing a steel anchor box of a circular arched main tower of a cable-stayed bridge comprises the following steps:

[0008] S1. Measure the axial alignment and verticality of the main tower, and monitor and collect stress and strain data of the main tower at different times and temperatures to determine the installation time period of the steel anchor box;

[0009] S2. Determine the installation positioning points of the segmental steel anchor boxes and arrange them within the installation time period determined in S1;

[0010] S3. Within the installation time period determined in S1, re-measure the installation positioning points determined in S2 and install the segmental steel anchor boxes;

[0011] S4. Within the installation time period determined in S1, determine the coordinates and elevations of the cable guide anchorage points and the cable guide outlet location points on the segment steel anchor box, and set the cable guide outlet IP layout mark point at the main tower wall outlet;

[0012] S5. During the installation period determined in S1, re-measure the IP marking point of the cable guide outlet determined in S4 and install the pre-buried cable guide section. One end of the pre-buried cable guide section is installed in the steel anchor box, and the other end is installed on the main tower and extends to the IP marking point of the cable guide outlet.

[0013] S6. Install the formwork on the main tower wall and connect the cable duct transition connection steel plate to the end of the pre-embedded cable duct section. The cable duct transition connection steel plate and the formwork are located on the same plane. Finally, pour concrete in the formwork cavity and connect the cable duct rear connection section to the cable duct transition connection steel plate.

[0014] S7. Repeat steps S2-S6 until the installation of each segment of the steel anchor box and its cable guide tube is completed.

[0015] Preferably, in step S1, monitoring points are set at the middle of each construction segment of the main tower and at the top of the tower segment by a total station to measure the axial linearity and verticality of the main tower; and four strain sensors are arranged at the four corner points of the tower column interface to monitor and collect stress and strain data of the main tower at different times and temperatures.

[0016] Preferably, in step S1, the installation time period is 7:00-9:00 in the morning and 19:00-21:00 in the evening.

[0017] Preferably, in step S2, before the concrete is poured to the bottom elevation of the first section of the steel anchor box, the embedded positions of the embedded steel plates and embedded steel bars are accurately located in advance using a total station, and the embedded steel plates and embedded steel bars are pre-embedded and arranged.

[0018] Preferably, in step S3, when installing the first section steel anchor box, the top surface elevation of the embedded steel plate is first remeasured.

[0019] Preferably, in step S2, when determining the installation positioning points of the steel anchor boxes of other segments, the rigid frame is first installed on the main tower column, and then the elevation and position of each corner point of the steel anchor box are laid out on the rigid frame by a total station to form the installation positioning points and arrange them on the rigid frame.

[0020] Preferably, in step S3, when installing other segments of steel anchor boxes, first use BIM technology to simulate and calculate the center of gravity and lifting points of each steel anchor box, then hoist the steel anchor box and temporarily reinforce it at the installation positioning point, and then use a total station to check the plane position and elevation multiple times during the installation period to ensure that its elevation deviation is ≤2mm, the plane position deviation is ≤5mm, and the deviation of the four corners of the anchor box is ≤2mm, and the steel anchor box is reinforced.

[0021] Preferably, in step S4, when staking out the cable duct anchor point and the cable duct outlet position point of the cable duct, the vertical axis of the cable duct is first laid out using a total station to determine the vertical plane where the cable duct is located, so that the relative deviation angle between the line connecting the cable duct anchor point and the cable duct outlet position point and the axis of the inclined cable meets the design requirements.

[0022] Preferably, in step S5, when installing the pre-buried section of the cable conduit, it is hoisted by a tower crane, and the plane position and elevation of the control point of the pre-buried section of the cable conduit are adjusted by a hand winch to ensure that they coincide with the IP layout identification point of the cable conduit outlet.

[0023] In summary, the present invention includes at least one of the following beneficial technical effects:

[0024] 1. By measuring the axial linearity and verticality of the main tower and monitoring and collecting the stress and strain data of the main tower at different times and temperatures, the elevation and displacement changes of the main tower during the construction process can be controlled, thereby controlling the changes in the installation positioning points of the steel anchor box, determining the optimal time for the installation of the steel anchor box, ensuring the accurate positioning of the steel anchor box, and shortening the installation monitoring time; the cableway pipe is set as a cable guide pre-embedded section, a cable guide transition connecting steel plate, and a cable guide rear connecting section for segmented installation, avoiding the modification of the climbing formwork of each section due to the inconsistent spatial coordinates of the cable guide of each section of the steel anchor box, and realizing the rapid and accurate positioning and installation of the anchor box in the tower, thereby improving the existing technology of the installation of the steel anchor box in the main tower, which is difficult to locate, resulting in inaccurate installation, and the problems of box construction period and construction cost, and realizing the rapid and accurate positioning construction of the anchor box in the tower;

[0025] 2. By determining the cable guide anchor point and the cable guide outlet location, and using these two points as auxiliary line setting, the relative deviation angle between the cable guide and the cable axis is controlled to meet the design requirements, achieving precise installation of the cable guide embedded section in the steel anchor box;

[0026] 3. BIM technology is used to simulate and calculate the center of gravity and lifting points of each steel anchor box section, and specific settings are made according to the different inclination conditions of the steel anchor box in each section. This can complete the rapid initial positioning and fine-tuning of the steel anchor box hoisting installation, thereby effectively reducing the time for repeated positioning and adjustment in traditional steel anchor box hoisting installation and speeding up the construction progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is an installation elevation view of the steel anchor box of the present invention;

[0028] Figure 2 yes Figure 1 Middle AA cross-section;

[0029] Figure 3 It is a construction flow chart of an embodiment of the present invention.

[0030] In the above drawings: 1. strain sensor; 2. cable guide anchoring point; 3. cable guide outlet position point; 4. cable guide pre-buried section; 5. cable guide outlet IP layout identification point; 6. cable guide transition connection steel plate; 7. cable guide rear connection section. DETAILED DESCRIPTION

[0031] The following is combined with Figure 1-3 The present invention will be further described.

[0032] Reference Figures 1 to 3 The embodiment of the present invention provides a method for positioning and constructing a steel anchor box of a circular arch main tower of a cable-stayed bridge, comprising the following steps:

[0033] S1. Measure the axial alignment and verticality of the main tower, and monitor and collect stress and strain data of the main tower at different times and temperatures to determine the installation time period of the steel anchor box;

[0034] During this process, monitoring points were set up in the middle of each construction section and at the top of the tower section by using a total station to measure the axial alignment and verticality of the main tower. Figure 2 And by arranging 4 strain sensors 1 at the four corner points of the tower column interface, specifically, 4 strain sensors can be arranged at the four corner points of each section of the bottom section of the upper tower column, the sections corresponding to the ZS21, ZS19, ZS11, and ZS9 cables, the center of the tower crown and its top and bottom sections, and the top and bottom sections of the lower tower column, so as to monitor and collect the stress and strain data of the main tower at different times and temperatures.

[0035] Since the monitoring data varies greatly during the installation of the steel anchor box at different times and temperatures, it is necessary to determine the time period when the observation data is stable for installation and construction; specifically, when the temperature is low and changes steadily in the morning and evening of a day, the observation data is stable, so it is chosen to install the steel anchor box in the morning and evening, and the preferred installation time period is 7:00-9:00 in the morning and 19:00-21:00 in the evening.

[0036] S2. Determine the installation positioning points of the segmental steel anchor boxes and arrange them within the installation time period determined in S1;

[0037] During this process, when determining the installation positioning point of the first section steel anchor box, within the installation time period determined in step S1, when the concrete is poured as the installation foundation and before reaching the bottom elevation of the first section steel anchor box, the total station is used to accurately locate the embedded positions of the embedded steel plates and embedded steel bars in advance, and the embedded steel plates and embedded steel bars are embedded to facilitate the subsequent installation of the first section steel anchor box.

[0038] At the same time, in this process, when determining the installation positioning points of the steel anchor boxes of other segments, the rigid frame is first installed on the main tower column, and then the coordinates of the corner points of the steel anchor boxes on different elevation surfaces are calculated according to the design drawings, and the elevations and positions of the corner points of the steel anchor boxes are laid out on the rigid frame through the total station to form installation positioning points and arrange them on the rigid frame; among them, the installation positioning points are set as follows: an iron plate with a hole drilled in the middle is welded on the rigid frame.

[0039] S3. Within the installation time period determined in S1, re-measure the installation positioning points determined in S2 and install the segmental steel anchor boxes;

[0040] During this process, the top elevation of the embedded steel plate needed to be re-measured before re-sizing the installation positioning points of the first segment's steel anchor box. A tower crane was used to assist in the installation of the first segment's steel anchor box. After the predicted top elevation of the steel plate was re-measured and confirmed, high-strength bolts were used to anchor the anchor box.

[0041] During this process, when installing other segments of steel anchor boxes, BIM technology is first used to simulate and calculate the center of gravity and lifting points of each steel anchor box to ensure stability when lifting the steel anchor box; then the steel anchor box is lifted and temporarily reinforced at the installation positioning point to complete the preliminary installation; then the total station is used to check the plane position and elevation multiple times during the installation period to ensure that its elevation deviation is ≤2mm, the plane position deviation is ≤5mm, and the deviation of the four corners of the anchor box is ≤2mm, and the steel anchor box is reinforced.

[0042] S4. Within the installation time period determined in S1, determine the coordinates and elevation of the cable guide anchor point 2 and the coordinates and elevation of the cable guide outlet position point 3 on the segment steel anchor box, and set the cable guide outlet IP layout mark point 5 at the main tower wall outlet;

[0043] In this process, the vertical axis of the cable guide tube is firstly laid out using a total station to determine the vertical plane where the cable guide tube is located, and the cable guide tube is accurately positioned on the vertical axis. The cable guide tube is only fixed left and right and can move up and down along the axis; then the coordinates of the cable guide tube outlet position point 3 at the designed tower end are laid out using the total station (mainly divided into mileage and elevation control), and the cable guide tube outlet position point 3 at the tower end is preliminarily located; then the coordinates of the cable guide anchor point 2 at the designed tower end are laid out using the total station (mainly divided into mileage and elevation control), and the cable guide anchor point 2 is located; and the relative deviation angle a between the line connecting the cable guide anchor point 2 and the cable guide outlet position point 3 and the axis of the inclined cable meets the design requirements.

[0044] S5. Within the installation time period determined in S1, re-measure the cable guide outlet IP layout mark point 5 determined in S4 and install the cable guide pre-buried section 4. One end of the cable guide pre-buried section 4 is installed in the steel anchor box, and the other end is installed on the main tower and extends to the cable guide outlet IP layout mark point 5.

[0045] During this process, when re-measuring the cable duct outlet IP layout identification point 5 determined in S4, its plane position and elevation deviation are controlled within 5mm; when installing the cable duct embedded section 4, it is hoisted by a tower crane, and the plane position and elevation of the control point of the cable duct embedded section 4 are adjusted using a hand hoist to ensure that it coincides with the cable duct outlet IP layout identification point 5.

[0046] S6. Install the formwork on the main tower wall, and connect the cable duct transition connection steel plate 6 to the end of the cable duct embedded section 4. The cable duct transition connection steel plate 6 and the formwork are located on the same plane. Finally, pour concrete in the formwork cavity, and connect the cable duct rear connection section 7 with a flange on the cable duct transition connection steel plate 6.

[0047] S7. Repeat steps S2-S6 until the installation of each segment of the steel anchor box and its cable guide tube is completed.

[0048] In the above construction steps, when making observations to determine the installation positioning points, the average value of the observation values ​​of the tower crane rotation in the four directions of large and small mileages and upstream and downstream is taken to eliminate the influence of the tower crane rotation and ensure the accuracy of finding the installation positioning points.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge, characterized in that: The following steps are involved: S1. Measure the axial alignment and verticality of the main tower, and monitor and collect stress and strain data of the main tower at different times and temperatures to determine the installation time period of the steel anchor box; S2. Determine the installation positioning points of the segmental steel anchor boxes and arrange them within the installation time period determined in S1; S3. Within the installation time period determined in S1, re-measure the installation positioning points determined in S2 and install the segmental steel anchor boxes; S4. Within the installation time period determined in S1, determine the coordinates and elevation of the cable guide anchor point (2) and the coordinates and elevation of the cable guide outlet position point (3) on the segment steel anchor box, and set the cable guide outlet IP layout mark point (5) at the main tower wall outlet; S5. Within the installation time period determined in S1, re-measure the IP layout mark point (5) of the cable guide outlet determined in S4, and install the cable guide pre-buried section (4). One end of the cable guide pre-buried section (4) is installed in the steel anchor box, and the other end is installed on the main tower and extends to the IP layout mark point (5) of the cable guide outlet; S6. Install the template on the main tower wall, and connect the cable duct transition connection steel plate (6) to the end of the cable duct embedded section (4), so that the cable duct transition connection steel plate (6) and the template are located on the same plane. Finally, pour concrete in the template cavity, and connect the cable duct rear connection section (7) to the cable duct transition connection steel plate (6); S7. Repeat steps S2-S6 until the installation of each segment of the steel anchor box and its cable guide tube is completed.

2. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 1, characterized in that: In step S1, monitoring points are set at the middle of each construction segment and the top of the tower segment by a total station to measure the axial alignment and verticality of the main tower; and four strain sensors (1) are arranged at the four corner points of the tower column interface to monitor and collect stress and strain data of the main tower at different times and temperatures.

3. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 2, characterized in that: In step S1, the installation time period is 7:00-9:00 in the morning and 19:00-21:00 in the evening.

4. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 1, characterized in that: In step S2, before the concrete is poured to the bottom elevation of the first section of the steel anchor box, the embedded positions of the embedded steel plates and embedded steel bars are accurately located in advance using a total station, and the embedded steel plates and embedded steel bars are pre-embedded and arranged.

5. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 4, characterized in that: In step S3, when installing the first section steel anchor box, first re-measure the top surface elevation of the embedded steel plate.

6. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 4, characterized in that: In step S2, when determining the installation positioning points of the steel anchor boxes of other segments, first install the rigid frame on the main tower column, and then use the total station to mark the elevation and position of each corner point of the steel anchor box on the rigid frame to form the installation positioning points and arrange them on the rigid frame.

7. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 6, characterized in that: In step S3, when installing the steel anchor boxes of other segments, first use BIM technology to simulate and calculate the center of gravity and lifting points of each steel anchor box, then hoist the steel anchor box and temporarily reinforce it at the installation positioning point, and then use a total station to check the plane position and elevation multiple times during the installation period to ensure that its elevation deviation is ≤2mm, the plane position deviation is ≤5mm, and the deviation of the four corners of the steel anchor box is ≤2mm, then reinforce the steel anchor box.

8. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 1, characterized in that: In step S4, when staking out the cable guide anchor point (2) and the cable guide outlet position point (3) of the cable guide, first use a total station to stake out the vertical axis of the cable guide, and determine the vertical plane where the cable guide is located, so that the relative deviation angle between the line connecting the cable guide anchor point (2) and the cable guide outlet position point (3) and the axis of the inclined cable meets the design requirements.

9. The method for positioning and constructing a steel anchor box for a circular arched main tower of a cable-stayed bridge according to claim 8, characterized in that: In step S5, when installing the cable conduit embedded section (4), it is hoisted by a tower crane, and the plane position and elevation of the control point of the cable conduit embedded section (4) are adjusted by a hand winch to ensure that it coincides with the cable conduit outlet IP layout identification point (5).

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