A method for construction of a plane composite curve beam by incremental launching

Abstract

The present application relates to a kind of plane composite curve beam pushing construction method, the starting point and the end point of bridge pushing construction section are determined, make the circular curve through starting point and end point and the point on the axis of bridge pushing construction section, as pushing trajectory line;Along pushing trajectory line, temporary support pier is erected, and symmetrical step jack is arranged on the both sides of temporary support pier along pushing trajectory line;Guide beam and beam body section are successively assembled on the temporary support pier on the extension line of pushing trajectory line, and pushing construction is carried out according to the pushing method of simple circular curve bridge.The present application pushes according to the circular curve fitted from itself to the complex composite curve bridge, can widen box girder at a time, to simplify beam body widening process;Unified jack step distance, and the position and angle of jack are fixed in the whole process, can effectively reduce the control difficulty of jack in pushing process.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, and relates to the installation and construction of bridge beams, specifically to a method for jacking construction of composite curved beams. Background Technology

[0002] The jacking method for bridge girder installation involves pouring or assembling the girder segment by segment at the bridgehead, and then using jacks to push it longitudinally through the temporary sliding bearing surfaces on each pier to position it in place. This method is commonly used for the installation of girder bridges. There are two main types of jacking methods: dragging and multi-point stepping. The latter is more widely used because it effectively reduces the horizontal reaction force on the piers and has three-dimensional displacement adjustment capabilities.

[0003] Multi-point step-launching employs three-way jacks, which are positioned on top of the piers during construction. To ensure force balance on both sides of the beam during launching, the jacks must be symmetrically arranged on both sides of the bridge axis, maintaining the longitudinal launching direction consistent with the bridge axis. Therefore, it is more suitable for bridges with relatively simple horizontal alignments, such as purely circular or straight bridges. However, in bridge design, to ensure driving safety and comfort, many bridges are designed as composite curved beams, with alignments including circular curve segments, straight segments, and complex curved segments (non-circular curve segments). For composite curved beams containing complex curved segments, the launching method presents the following main difficulties during construction:

[0004] 1. The curvature of a composite curved beam is constantly changing. During the jacking process, its axial position is not fixed above the same pier top, while the position of the jacks cannot be moved. To ensure the force balance on both sides of the beam bottom, the beam bottom needs to be temporarily widened to make the jacks symmetrical on both sides of the widened beam axis. However, as the beam moves, its axial position will constantly change and deviate from the symmetry line of the jacks on both sides, requiring the beam to be widened again, making the construction process extremely complicated. In actual construction, in order to simplify the widening process, a universal widening is often performed based on the maximum deviation of the beam axis, resulting in a significant increase in construction costs.

[0005] 2. During the jacking of curved bridges, the step distances of the walking jacks on both sides of the bridge axis are different. For simple circular curved beams, the difference in the layout of the jacks on both sides of the bridge axis is fixed and relatively easy to adjust. However, for composite curved beams, the step distance difference of the jacks on both sides of the bridge axis changes constantly, and the jacking direction also needs to be changed at all times. The control and adjustment reference systems for the walking jacks are numerous, which can easily lead to confusion, making the actual jacking process extremely complex and difficult to control.

[0006] Figure 1This is a schematic diagram of the plan structure of a common interchange ramp bridge, which has two spans, including pier 101, pier 202 and pier 303, with the span between pier 202 and pier 303 being a cross-line segment.

[0007] Figure 2 This is the axis diagram of the aforementioned ramp bridge. Its alignment is a compound curve, where the section from point A to point B is a circular curve, the section from point B to point C is a complex curve segment, and the section from point C to point D is a straight line segment. To avoid affecting traffic flow below, the bridge is preferably constructed using the incremental launching method. However, as can be seen, both spans of the bridge include complex curve segments. Whether the entire beam is launched or the beams are launched in sections, the launching route is a compound curve, presenting the same difficulties encountered in the incremental launching of composite curve beams. Summary of the Invention

[0008] The purpose of this invention is to provide a method for jacking planar composite curved beams, which simplifies the construction process, reduces construction difficulty, and solves the problems encountered in the jacking construction of composite curved beams.

[0009] The technical solution of the present invention is as follows:

[0010] A method for jacking a planar composite curved beam, characterized by comprising the following steps:

[0011] (1) Determine the jacking trajectory line: First, determine the starting point and ending point of the bridge jacking construction section, then draw the design axis of the bridge jacking construction section, and draw a circular curve passing through the starting point and ending point of the jacking construction section and any point on the design axis of the bridge jacking construction section except the starting point and ending point, as the jacking trajectory line;

[0012] (2) Erect a certain number of temporary supports along the jacking trajectory line and its extension line; set up walking jacks on each temporary support, and arrange the walking jacks on each support symmetrically on both sides of the jacking trajectory line.

[0013] (3) Assemble the guide beam and beam segments sequentially on the temporary support on the extension line of the jacking trajectory. When there is a deviation between the designed longitudinal axis of the beam segment and the jacking trajectory, widen and reinforce the bottom of the beam segment according to the deviation value so that the longitudinal axis of the widened bottom of the beam is consistent with the jacking trajectory.

[0014] (4) The jacking construction is carried out according to the jacking method of simple circular curve bridge. After each segment is assembled, it is jacked forward by one segment until all beam segments are jacked into place.

[0015] The essence of this invention is to push a complex composite curve bridge according to a circular curve fitted from itself, providing a simplified path and method based on a simple line shape and a clear, fixed reference position, which has the following advantages:

[0016] Since the curvature of the circular curve is constant, the deviation of the beam axis from the circular curve is constant at any position. Therefore, the widening and reinforcement positions are fixed, and the box girder can be widened at one time, ensuring that the entire path of the jacking process is applicable, thereby simplifying the beam widening or reinforcement process.

[0017] Since the curvature of a circular curve is constant, the curve can be pushed by setting a fixed step distance difference between the walking jacks that push the inner and outer sides of the curve at the same position. This can not only unify the pushing step distance, but also fix the position and angle of the pushing jacks throughout the process, effectively reducing the control difficulty of the walking jacks.

[0018] This invention has a wide range of applications, not only applicable to the jacking construction of composite curve beams with unidirectional curvature changes, but also applicable to various construction scenarios such as composite curve bridges with reverse bidirectional curvature changes and widening bridges. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the plan structure of a composite curve overpass ramp bridge;

[0020] Figure 2 yes Figure 1 A schematic diagram of the longitudinal axis of the bridge shown.

[0021] Figure 3 This is a construction flowchart of the present invention;

[0022] Figure 4 Yes Figure 1 A schematic diagram of the jacking circular curve fitted to the curved bridge shown.

[0023] Figure 5 This is a schematic diagram showing the arrangement of temporary supports based on the jacking circular curve;

[0024] Figure 6 This is a schematic diagram showing the arrangement of the stepping jacks based on the jacking circular curve.

[0025] Figures 7 to 9 This is a schematic diagram illustrating the pushing motion along a circular curve, where:

[0026] Figure 7 This is a schematic diagram showing the assembly and jacking status of the guide beam.

[0027] Figure 8 This is a schematic diagram showing the assembly and jacking status of the bridge segments after the guide beam.

[0028] Figure 9 This is a schematic diagram showing the state of a bridge after one span has been jacked up. Detailed Implementation

[0029] The following is through the analysis of Figure 1The method of the present invention is described in detail through the jacking process of the composite curve overpass ramp bridge shown.

[0030] The overall construction process of this invention is as follows: Figure 3 As shown, the specific construction process is as follows:

[0031] (1) Determine the jacking trajectory: First, determine the starting point and ending point of the bridge jacking construction section, then draw the design axis of the bridge jacking construction section, and draw a circular curve passing through the starting point and ending point of the jacking construction section and any point on the design axis of the bridge jacking construction section except for the starting and ending points, as the jacking trajectory. Generally, the permanent pier of the bridge is selected as the starting and ending point.

[0032] During the specific construction process, Figure 1 In the illustrated embodiment, the bridge is designed as a two-span structure. Initially, the permanent piers of the entire bridge are used as the starting and ending points, specifically pier 101 and pier 103. However, after drawing the circular curve of the jacking trajectory using the above method, it was found that the deviation between the main beam axis and the circular trajectory line was too large. If jacking is carried out according to this circular curve, the cost of temporarily widening the bottom of the beam would be too high, and the safety level would also need to be improved. To reduce costs, segmented jacking of the bridge is considered. Since the span between piers 102 and 103 crosses an existing railway line, jacking construction is prioritized. The starting point of this jacking construction segment is permanent pier 102, and the ending point is permanent pier 103.

[0033] like Figure 4 As shown, the center points O2 and O3 of permanent piers 102 and 103 were found. A circular curve passing through O2, O3, and any point O on the bridge axis of this section was drawn as the jacking trajectory line L1 for the jacking construction. The maximum deviation between the jacking trajectory line L1 and the bridge axis L0 is at point E, which is 230.3 mm. This deviation value is within the normal safety assurance level.

[0034] (2) For example Figure 5 , Figure 6 As shown, a certain number of temporary supports 1 are erected along the jacking trajectory line L1 and its extension line; walking jacks 2 are set on each temporary support, and the walking jacks 2 on each support are symmetrically arranged on both sides of the jacking trajectory line L1.

[0035] (3) such as Figure 7 , Figure 8 As shown, guide beam 3 and beam segment 4 are assembled sequentially on temporary support 1 on the extension line of the jacking trajectory line L1 near the jacking starting point O2. When there is a deviation between the designed longitudinal axis of beam segment 4 and the jacking trajectory line, the bottom of the beam segment is widened and reinforced according to the deviation value so that the longitudinal axis of the widened bottom of the beam is consistent with the jacking trajectory line.

[0036] (4) such as Figure 8 , Figure 9As shown, the jacking construction was carried out using the jacking method for simple circular curve bridges. After each beam segment 4 was assembled, it was jacked forward by one section until all beam segments 4 were jacked into place. The guide beam was then removed, completing the jacking construction.

[0037] After the bridge span between piers 102 and 103 is completed, the bridge section between piers 101 and 102 can be jacked up using the same method. In this embodiment, since the bridge span between piers 101 and 102 is a non-crossing section, this bridge section can also be constructed using the hoisting method without affecting the traffic on the existing line.

[0038] Since the beam needs to be widened when the beam segment axis does not match the launching curve, in order to minimize the widening cost, in the specific implementation of this invention, when determining the launching trajectory line, the root mean square deviation of the deviation distance between the left and right sides of the launching trajectory line and the beam axis should be minimized as much as possible. Specifically, the following methods can be adopted:

[0039] Option 1: First, construct a straight line segment between the starting and ending points of the bridge jacking construction section. Then, draw a perpendicular line through the midpoint of this straight line segment and find the intersection of this perpendicular line and the design axis of the bridge jacking section. Next, construct a circular curve passing through the starting and ending points of the jacking construction and this intersection point as the jacking trajectory line. This option is suitable for complex curves with relatively gentle curvature changes.

[0040] Option 2: First, construct a straight section between the starting and ending points of the bridge jacking construction segment. Measure the maximum and minimum distance deviations between this straight section and the design axis of the bridge jacking segment. Take the average of the maximum and minimum deviations. Then, find a point on the design axis of the bridge jacking segment that is equal to or closest to this average value. Draw a circular curve passing through the starting and ending points of the jacking construction and this point, as the jacking trajectory line. This option is suitable for complex curves with significant curvature changes.

Claims

1. A method for incremental launching of a flat composite curved beam, characterized in that, The method comprises the following steps: (1) determining a pushing track line: first determining the starting point and the ending point of the pushing construction section of the bridge, then drawing the design axis of the pushing construction section of the bridge, and making a circular curve passing through the starting point and the ending point of the pushing construction section and any point on the design axis of the pushing construction section of the bridge except the starting point and the ending point, as the pushing track line; (2) erecting a certain number of temporary piers along the pushing track line and the extension line thereof; setting walking jacks on each temporary pier, and the walking jacks on each temporary pier are symmetrically arranged on both sides of the pushing track line; (3) sequentially assembling the guide beam and the beam segment on the temporary piers on the extension line of the pushing track line, and when the design longitudinal axis of the beam segment deviates from the pushing track line, the bottom of the beam segment is widened and reinforced according to the deviation value, so that the longitudinal axis of the widened beam bottom is consistent with the pushing track line; (4) pushing according to the pushing method of the simple circular curve bridge, pushing a segment forward after each segment is assembled, until all the beam segments are pushed into place.

2. The incremental launching construction method of a planar composite curve beam according to claim 1, wherein: When the bridge has two or more spans, and the curvature of the whole bridge is relatively large, the pushing construction is performed in sections, and the starting point and the ending point of each section are two permanent piers at the two ends of the section, and each section is pushed according to the method of steps (1) to (4).

3. The incremental launching construction method of a planar composite curve beam according to claim 1, wherein: In the step (1), when the pushing track line is determined, first a straight line section between the starting point and the ending point of the pushing construction section of the bridge is made, a perpendicular line passing through the midpoint of the straight line section is made, and the intersection point of the perpendicular line and the design axis of the pushing section of the bridge is found, and a circular curve passing through the starting point and the ending point of the pushing construction and the intersection point is made as the pushing track line.

4. The incremental launching construction method of a planar composite curve beam according to claim 1, wherein: In the step (1), when the pushing track line is determined, first a straight line section between the starting point and the ending point of the pushing construction section of the bridge is made, the maximum distance deviation and the minimum distance deviation between the straight line section and the design axis of the pushing section of the bridge are measured, the average value of the maximum deviation and the minimum deviation is taken, and the point on the design axis of the pushing section of the bridge equal to or closest to the average value is found, and a circular curve passing through the starting point and the ending point of the pushing construction and the point is made as the pushing track line.

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