Construction method for unbalanced installation of arch ribs on both sides of intermediate piers of continuous concrete-filled steel tube arch bridges

Abstract

The present invention relates to the technical field of bridge construction, and specifically discloses a construction method for unbalanced installation of arch ribs on both sides of the middle pier of a continuous concrete-filled steel tube arch bridge, which includes the following steps: (1) Install partial arch rib segments on each side of the middle pier of the continuous concrete-filled steel tube arch bridge, and tension the stay cables for the corresponding arch rib segments while installing. (2) Use the stabilizing cable to offset the middle pier towards the side of the arch rib segment on one side of the middle pier. (3) Then, starting from the opposite side of the stabilizing cable, continue to install the arch rib segments and tension the stay cables for the arch rib segments at the same time. After completion, install the arch rib segments on the opposite side of the arch rib segments, and tension the stay cables for these two groups of arch rib segments at the same time. Repeat this process until all the arch rib segments on both sides of the middle pier are installed crosswise. The method of the present invention not only effectively solves the problems of pier top deviation and excessive pier bottom stress of the middle pier caused by crosswise installation of arch ribs on both sides, but also helps to reduce the risks brought by the unbalanced construction process.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and particularly to a construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily to be regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Concrete-filled steel tube arch bridges are widely used in the construction of mountain bridges due to many advantages such as large stiffness, high bearing capacity, and good durability. The segment installation of concrete-filled steel tube arch bridges usually adopts the cable hoisting technology. When installing the arch rib segments of a single-span concrete-filled steel tube arch bridge, the tie cables and the anchor cables need to be tensioned simultaneously. After the tie cables and the anchor cables are anchored on both sides of the bridge pier, the force is transmitted to the ground, thus forming a stable structural system. Due to terrain limitations, sometimes it is necessary for the arch bridge to span two adjacent "V"-shaped canyons, and then the double-span continuous arch bridge emerges (see the attached drawings of the specification Figure 1 ).

[0004] For the arch ribs (i.e., the left arch rib and the right arch rib) on both sides of the intermediate pier of the double-connected arch (see the attached drawings of the specification Figure 2 ), when the arch rib segments on both sides are installed simultaneously and the tie cables are tensioned simultaneously, the structure is in a balanced and safe state. However, the actual situation is that since the cable hoisting system can only transport one segment to the installation position at a time, especially under terrain limitations. This results in the inability to install the arch ribs on both sides of the intermediate pier simultaneously. For example, when installing the left arch rib segment first and tensioning the left tie cable, the right side of the intermediate pier is in an unbalanced state due to the lack of symmetric tie cable force, which further causes the top of the intermediate pier to deflect to the left, and at the same time, tensile stress appears at the right side position of the pier bottom. As the number of installed arch rib segments increases, this construction method will lead to excessive horizontal deformation at the top of the intermediate pier and excessive tensile stress at the pier bottom. Coupled with the fact that some intermediate piers adopt a hollow structure, especially for the hollow intermediate pier, the above construction method brings potential safety problems to the construction safety. Summary of the Invention

[0005] In view of the above problems, the present invention provides a construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge, which effectively solves the problems of the top deflection of the intermediate pier and excessive stress at the pier bottom caused by the cross-installation of the arch ribs on both sides, and helps to reduce the risks brought by the unbalanced construction process. Specifically, the technical solution of the present invention is as follows.

[0006] A construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge, comprising the following steps:

[0007] (1)In the case where the arch ribs on both sides of the intermediate pier of a concrete-filled steel tube arch bridge cannot be installed simultaneously due to terrain restrictions, during construction, first install partial arch rib segments on each side of the intermediate pier, and while installing, tension the stay cables corresponding to the respective arch rib segments to maintain the stability of these arch rib segments.

[0008] (2)Prepare a stabilizing cable, connect its upper end to the top of the intermediate pier, and then fix the lower end of the stabilizing cable on the base surface on one side of the intermediate pier and tension it so that the intermediate pier deflects a set amount towards the side where the inclined stabilizing cable is located, and the stabilizing cable and an arch rib segment on a certain side of the intermediate pier are on the same side.

[0009] (3)Then, starting from the opposite side of the stabilizing cable, continue to install arch rib segment a and partially tension the stay cable a of this arch rib segment a, and use the formed partial stay cable force to exert a partial pulling effect on the intermediate pier. After completion, install arch rib segment b on the opposite side of arch rib segment a, and tension the stay cable b of this arch rib segment b so that the formed partial stay cable force is the same as the partial stay cable force of arch rib segment a. Then, simultaneously tension stay cable a and stay cable b until the same final stay cable force is reached. After completion, continue to install arch rib segments starting from the opposite side of the stabilizing cable, and so on until all the arch rib segments on both sides of the intermediate pier are installed crosswise.

[0010] Further, in step (1), the number of the partial arch rib segments is based on: when an arch rib segment is installed on one side of the intermediate pier and a symmetric arch rib segment has not been installed on the opposite side, the pier top deflection amount generated by the intermediate pier at this time is not greater than 3 cm and the pier bottom stress does not exceed 1.6 MPa. It should be understood that the installation of this part of the rib segments can be carried out in an unbalanced state.

[0011] Further, in step (1), the stay cable is inclined, its upper end is connected to the side wall of the intermediate pier, and its lower end is connected to the corresponding arch rib segment. Optionally, the angle between the stay cable and the horizontal plane is 2.5 - 37°.

[0012] Further, in step (2), a connection buckle for detachably connecting with the lower end of the stabilizing cable is anchored in the base surface.

[0013] Further, in step (2), the set amount is that the top of the intermediate pier deflects 2 - 4 cm towards the side where the stabilizing cable is located by the pulling of the stabilizing cable.

[0014] Further, in step (2), the angle between the stabilizing cable and the horizontal plane is 10° to 45°, which can be specifically determined according to the terrain of the construction site. Generally speaking, the smaller the angle, the easier it is to effectively pull the intermediate pier, so that when the arch rib segments on both sides of the intermediate pier are installed, the stabilizing cable can more effectively limit the horizontal deformation of the intermediate pier.

[0015] Further, in step (3), the partial cable force is not greater than 60% of the final cable force. During the process of tensioning the cable a, since the offset of the intermediate pier will decrease under the action of the cable force, if the cable force of the cable a is tensioned to reach the final cable force at one time, it will cause the offset of the intermediate pier to return to zero or even become negative, that is, to deflect to the side of the arch rib segment a, resulting in excessive horizontal deformation of the intermediate pier and excessive tensile stress at the pier bottom. For this reason, the present invention proposes a method of first partially tensioning the cable a to form a partial cable force, so as to ensure that the intermediate pier maintains a certain offset. This can not only meet the installation requirements of the arch rib segment a, but also utilize the balanced state formed after installing the arch rib segment b, and simultaneously tension the cable a and the cable b until they reach the same final cable force. In this way, while the installation of the arch rib segment a and the arch rib segment b is completed, the offset of the intermediate pier returns to the initial state, which is convenient for the installation of subsequent arch rib segments.

[0016] Further, in step (3), after all the arch rib segments are installed, the stabilizing cable can be removed.

[0017] Further, in step (2), the stabilizing cable at least includes two ropes arranged in parallel. After all the arch rib segments are installed in step (3), only the lower end of the stabilizing cable is disassembled, and the upper end still remains connected to the intermediate pier. Then, the ropes obtained by separating the stabilizing cable are distributed on both sides of the intermediate pier and respectively connected to the bridge deck columns fixed on the arch rib segments, and the ropes are tensioned.

[0018] Further, after the bridge deck paving construction supported on the bridge deck columns is completed, the stabilizing cable is removed from the intermediate pier and the bridge deck columns.

[0019] Further, the cable and the stabilizing cable are both steel strands formed by stranding a plurality of steel wires, which not only have high strength but also high toughness. Preferably, the surface of the steel strand has an anti-corrosion layer.

[0020] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0021] The present invention proposes a method of using a stabilizing cable to increase the anti-pushing stiffness of the intermediate pier of a continuous concrete-filled steel tube arch bridge, so as to resist the horizontal force in the unbalanced installation state of the arch rib segments, thereby well realizing the control of the deformation and stress of the intermediate pier and preventing the instability of the intermediate pier during the installation process of the arch rib segments, and further causing engineering safety problems. At the same time, after the installation of the arch rib segments is completed, the present invention also utilizes the convenience provided by the stabilizing cable to limit the deviation of the bridge deck columns, enhance the stability of the structure, and thus contribute to further improving the construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0023] Figure 1 It is a schematic structural diagram of a double-span continuous arch bridge in the foregoing background art.

[0024] Figure 2 It is a schematic structural diagram of the intermediate pier of the double-span continuous arch bridge in the foregoing background art.

[0025] Figure 3 It is a schematic structural diagram of the intermediate pier of a double-arch with a stabilizing cable tensioned in the following embodiments.

[0026] Figure 4 It is a schematic diagram of installing the left arch rib segment in the following embodiments.

[0027] Figure 5 It is a schematic diagram of installing the right arch rib segment in the following embodiments.

[0028] Figure 6 It is a schematic structural diagram of enhancing the stability of the bridge deck columns by using a stabilizing cable in the following embodiments.

[0029] Figure 7 It is the finite element simulation test result of the unbalanced installation construction method with a stabilizing cable added in the following embodiments.

[0030] Figure 8 It is the finite element simulation test result of the unbalanced installation construction method without a stabilizing cable added in the following embodiments.

[0031] The above marks in the figures respectively represent: 1 - intermediate pier, 2 - left arch rib segment, 3 - right arch rib segment, 4 - fastening cable, 5 - stabilizing cable, 6 - connecting buckle, 7 - bridge deck column, 8 - bridge deck. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0033] It should be noted that the terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] For the convenience of description, if the words "upper", "lower", "left", and "right" appear in the present invention, they only indicate the same directions as the upper, lower, left, and right of the accompanying drawings themselves, and do not limit the structure. They are merely for facilitating the description of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to needs to have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0035] The construction method for the unbalanced installation of the arch ribs on both sides of the intermediate pier of the continuous concrete-filled steel tube arch bridge of the present invention will be further described in conjunction with the accompanying drawings of the specification and specific embodiments. Specifically, the method includes the following steps:

[0036] (1) Refer to Figure 2 , in view of the situation where the arch rib segments on both sides of the intermediate pier 1 of the continuous concrete-filled steel tube arch bridge cannot be installed simultaneously due to terrain restrictions, the method adopted in this embodiment is as follows: First, use a cable hoisting system to install four arch rib segments (i.e., four left-side arch rib segments 2 and four right-side arch rib segments 3) on the left and right sides of the intermediate pier 1 respectively, and adopt a cross-installation method on the left and right sides. At the same time, tension the tie cables 4 for the left-side arch rib segments 2 and the right-side arch rib segments 3 to ensure the stability of these arch rib segments. The tie cable 4 is inclined, with its upper end connected to the side wall of the intermediate pier 1 and its lower end connected to the corresponding arch rib segment. The included angle between the tie cable 4 and the horizontal plane ranges from 2.5 to 37°. As the number of the installed arch rib segments increases, the longer the arch rib cantilever length formed, and at this time, the smaller the included angle between the tie cable and the horizontal plane, so the greater the horizontal force caused by the weight of the arch rib segment, and the greater the horizontal deformation at the top of the intermediate pier and the stress at the bottom of the pier caused by the unbalanced hoisting. In this embodiment, the included angles between the tie cables 4 corresponding to the four arch rib segments and the horizontal plane are 37°, 30°, 20°, and 15° from bottom to top in sequence. The tie cable 4 is a steel strand composed of several steel wires twisted together, which not only has high strength but also high toughness, and is convenient for providing good tie cable force for the arch rib segments.

[0037] (2) As the number of arch rib segments installed on both sides of the intermediate pier 1 increases, the connection position of the cable 4 to the intermediate pier 1 becomes higher and higher. When installing the arch rib segments on one side of the intermediate pier 1, the tension of the cable 4 after tensioning may cause the intermediate pier 1 to shift, resulting in tensile stress at the bottom position of the intermediate pier 1. Especially as the number of arch rib segments continues to increase, it will eventually lead to excessive horizontal deformation at the top of the intermediate pier 1 and excessive tensile stress at the pier bottom (taking the pier top offset of the intermediate pier greater than 3 cm and the pier bottom stress exceeding 1.6 MPa as the standard), which affects the construction safety.

[0038] Therefore, referring to Figure 3 , in this embodiment, a tensioned inclined stabilizing cable 5 (a steel strand composed of several steel wires twisted together) is provided on the right side of the intermediate pier 1: its upper end is connected to the top of the intermediate pier 1, and the lower end is fixed on the foundation surface on the right side of the intermediate pier 1, so that the intermediate pier 1 is offset to the right by a set amount (such as 2 cm, 3 cm, 4 cm, etc.). The included angle between the stabilizing cable 5 and the horizontal plane can be arbitrarily selected within the range of 10° to 45°, such as 10°, 20°, 30°, 45°, etc., or the included angle outside the above range can also be selected according to the actual terrain characteristics.

[0039] (3) Referring to Figure 4 , starting from the left side of the intermediate pier 1, that is, the opposite side of the stabilizing cable 5, install the fifth left arch rib segment 2 and its corresponding cable 4, and partially tension the cable 4 to form a partial cable force on the fifth left arch rib segment 2 (50% of the final cable force). At this time, due to the restriction of the stabilizing cable 5 on the intermediate pier 1, the anti-pushing stiffness of the intermediate pier is enhanced, and the pier top deflection and excessive tensile stress at the pier bottom during the unbalanced installation of the arch rib segments on both sides of the intermediate pier 1 are restricted. After completion, install the fifth right arch rib segment 3 on the right side of the intermediate pier 1 and its corresponding cable 4 (refer to Figure 5 ), and then tension the cable 4 so that its cable force is the same as the partial cable force of the fifth left arch rib segment 2. After completion, simultaneously tension the cables 4 of the fifth left arch rib segment 2 and the fifth right arch rib segment 3 to form symmetric cable forces. At this time, the intermediate pier 1 returns to the balanced state, so that after the installation of the fifth right arch rib segment 3 is completed, the intermediate pier 1 returns to the initial rightward offset amount. Continue to install the sixth left arch rib segment 2 and its corresponding cable 4 on the left side of the intermediate pier 1 according to the above method until all the arch rib segments on both sides of the intermediate pier 1 are cross-installed.

[0040] After installing all the arch rib segments, the stabilizing cable 5 can be removed. It should be understood that the stabilizing cable 5 can also be arranged on the left side of the intermediate pier 1, and the difference lies in that the installation sequence of the subsequent arch rib segments is opposite to that of step (3) above. In this embodiment, the stabilizing cable 5 is used to increase the anti-pushing stiffness of the intermediate pier 1 of the continuous concrete-filled steel tube arch bridge, which is equivalent to adding external prestressed steel bars, so as to resist the horizontal force in the unbalanced installation state of the arch rib segments, and well realize the control of the deformation and stress of the intermediate pier, and prevent the intermediate pier from losing stability during the installation process of the arch rib segments. At the same time, the stabilizing cable 5 and the intermediate pier 1 form a stable triangular structure, so that the construction can be carried out under the condition of building the cross-section of the intermediate pier to be smaller, which can save materials and reduce costs.

[0041] For another embodiment, in the unbalanced installation construction method of the above embodiment, the surface of the steel strand has an anti-corrosion layer to increase the service life of the tie cable 4 and the stabilizing cable 5.

[0042] For another embodiment, refer to Figure 3 、 Figure 4 or Figure 5 In step (2) of the unbalanced installation construction method of the above embodiment, a connecting buckle 6 is anchored in the base surface so as to be detachably connected to the lower end of the stabilizing cable 5, which is convenient for the connection and removal of the stabilizing cable 5.

[0043] For another embodiment, refer to Figure 6 In the unbalanced installation construction method of the above embodiment, the stabilizing cable 5 used in step (2) at least includes two ropes arranged side by side (each rope is a steel strand formed by stranding a number of steel wires). On the one hand, the overall strength of the stabilizing cable 5 can be enhanced, which is convenient for providing a more sufficient pulling effect. On the other hand, after installing all the arch rib segments in step (3) above, in this embodiment, only the lower end of the stabilizing cable 5 is disassembled, and the upper end still remains connected to the intermediate pier 1. Then, after distributing each rope obtained by separating the stabilizing cable 5 to both sides of the intermediate pier 1, they are respectively connected to the bridge deck columns 7 fixed on the left arch rib segment 2 and the right arch rib segment 3, and the ropes are tensioned, so as to use the intermediate pier 1 with greater stiffness to limit the possible deviation of the bridge deck columns 7 during the laying process of the bridge deck 8, and enhance the overall stability of the support structure formed by the arch rib segments and the bridge deck columns 7. After the bridge deck 8 paving construction is completed, the two ends of the stabilizing cable 5 are respectively removed from the intermediate pier 1 and the bridge deck columns 7.

[0044] In a further embodiment, in this embodiment, the finite element simulation technology is used to simulate and test the unbalanced installation construction method of the arch ribs on both sides of the intermediate pier of the above continuous concrete-filled steel tube arch bridge. The results are as Figure 7 and Figure 8As shown in the figure. Among them: the Figure 7 is the test result obtained after establishing the above-mentioned stabilizing cable 5 on the intermediate pier 1, which shows that when the twelfth left arch rib segment of the intermediate pier 1 is installed and the tension of its stay cable is increased to 50% of the final stay cable tension, the intermediate pier 1 deflects 23 mm to the left, and the stress at the bottom of the pier is -0.4 MPa, that is, no tensile stress appears at the bottom of the pier. The Figure 8 is the test result obtained without establishing the above-mentioned stabilizing cable 5 on the intermediate pier 1, which shows that when the twelfth left arch rib segment of the intermediate pier 1 is installed and the tension of its stay cable is increased to 50% of the final stay cable tension, the intermediate pier 1 deflects 99 mm to the left, and the tensile stress at the bottom of the pier is 2.6 MPa, that is, tensile stress appears at the bottom of the pier. It is proved that the stabilizing cable 5 can effectively limit the generation of stress at the bottom of the pier and helps to prevent the problem of instability of the intermediate pier during the installation of the arch rib segment.

[0045] Finally, it should be noted that any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation of the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. Construction method for unbalanced installation of arch ribs on both sides of intermediate piers of continuous concrete-filled steel tube arch bridges, characterized in that, It includes the following steps: (1) In case that the arch ribs on both sides of the intermediate pier of a concrete-filled steel tube arch bridge cannot be installed simultaneously due to terrain restrictions, during construction, first install partial arch rib segments on each side of the intermediate pier respectively, and while installing, tension the tie cables corresponding to the said arch rib segments to keep the stability of these arch rib segments; (2) Prepare a stabilizing cable, connect its upper end to the top of the intermediate pier, then fix the lower end of the stabilizing cable on the base surface on one side of the intermediate pier and tension it, so that the intermediate pier deflects a set amount towards the side where the inclined stabilizing cable is located, and the stabilizing cable and an arch rib segment on a certain side of the intermediate pier are on the same side; (3) Then start from the opposite side of the stabilizing cable, continue to install arch rib segment a and partially tension the tie cable a of this arch rib segment a, and use the formed partial tie cable force to form a partial pulling effect on the intermediate pier; After completion, install arch rib segment b on the opposite side of arch rib segment a, and tension the tie cable b of this arch rib segment b to make the formed partial tie cable force the same as the said partial tie cable force of arch rib segment a; then tension tie cable a and tie cable b simultaneously until the same final tie cable force is reached; After completion, continue to install arch rib segments starting from the opposite side of the stabilizing cable, and repeat this process until all the arch rib segments on both sides of the intermediate pier are cross-installed; In step (2), a connection buckle for detachably connecting with the lower end of the stabilizing cable is anchored in the base surface; In step (2), the stabilizing cable at least includes two parallel ropes. After installing all the arch rib segments in step (3), only detach the lower end of the stabilizing cable, and keep the upper end still connected to the intermediate pier. Then, after distributing the ropes obtained by separating the stabilizing cable to both sides of the intermediate pier, connect them to the bridge deck columns fixed on the arch rib segments respectively, and tension the ropes; 2. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that In step (1), the number of the partial arch rib segments is based on: when installing a certain arch rib segment on one side of the intermediate pier and there is no symmetric arch rib segment installed on the opposite side yet, the pier top deflection amount generated by the intermediate pier at this time is not greater than 3 cm, and the pier bottom stress does not exceed 1.6 MPa; 3. The construction method for unbalanced installation of arch ribs on both sides of the middle pier of a continuous concrete-filled steel tube arch bridge according to claim 2, characterized in that, In step (1), the tie cable is inclined, its upper end is connected to the side wall of the intermediate pier, and the lower end is connected to the corresponding arch rib segment; 4. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 3, characterized in that The included angle between the tie cable and the horizontal plane is 2.5 - 37°; 5. The construction method for unbalanced installation of arch ribs on both sides of the middle pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that, The tie cable and the stabilizing cable are both steel stranded wires formed by stranding several steel wires; 6. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 5, characterized in that The surface of the steel stranded wire has an anti-corrosion layer; 7. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that, In step (2), the set amount is that the top of the intermediate pier deflects 2 - 4 cm towards the side where the stabilizing cable is located by the pulling of the stabilizing cable; 8. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that In step (2), the included angle between the stabilizing cable and the horizontal plane is 10 - 45°; 9. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that, In step (3), the partial tie cable force is not greater than 60% of the final tie cable force; 10. The construction method for unbalanced installation of arch ribs on both sides of the intermediate pier of a continuous concrete-filled steel tube arch bridge according to claim 1, characterized in that, After the bridge deck paving construction supported on the bridge deck columns is completed, then remove the stabilizing cable from the intermediate pier and the bridge deck columns.

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