Implementation method for temporary height connection and resetting of steel pipe concrete column in top-down method foundation pit

Abstract

The present application belongs to the field of construction structure, and relates to an implementation method for temporary height connection and resetting of a steel pipe concrete column in a top-down method foundation pit. The technical scheme comprises the following steps: S1, temporary nodes and permanent nodes are pre-buried in the top-down excavation stage; S2, temporary structure is removed and column top resetting is formed; and S3, surface layer is closed and finished. The problems of in-situ utilization of the steel pipe concrete column under the conditions of large-scale open area of the top plate such as a atrium and low column top in the top-down method foundation pit project and connection of beams and columns in different stages are solved. The technology can simultaneously meet the safe connection of the temporary support beam and the temporary height connection column in the open area of the top plate in the top-down excavation stage, the safe connection of the structure beam and the structure column at the original design column top position, and the connection structure requirement of the structure beam and the structure column after the temporary height connection column is removed and the column top is reset after the basement top-down construction is completed.

Description

Technical Field

[0001] This invention belongs to the field of building structures, and particularly relates to the implementation method of temporarily raising and resetting steel-concrete composite columns when the top of the structural columns falls in the case of reverse construction foundation pit engineering. Technical Background

[0002] In underground space development under complex environmental conditions or with special construction requirements, deep foundation pit engineering often employs the reverse construction method. This method utilizes the structural beams and slabs of each underground level to replace temporary horizontal supports, and uses the main structural piles and columns to replace the vertical support structures under the horizontal supports. The beams, slabs, columns, and piles are designed to meet the needs of both the foundation pit stage and the normal use stage. In the pile and column design for the reverse construction method, a "one column, one pile" arrangement system is typically adopted. This involves setting steel-concrete composite columns or angle steel lattice columns at the structural frame column locations, with engineering piles serving as column piles beneath these columns. The basement roof slab and the structural beams and slabs of each underground level are connected to the steel-concrete composite columns or angle steel lattice columns via concrete ring beams or steel corbels. However, in some commercial complexes with complex building functions, the first basement level is often designed as a large atrium area, resulting in a large open area of ​​the basement roof slab and structural columns that drop to the first basement level. This fails to meet the dual requirements of ensuring the continuity of horizontal force transmission and vertical support of the basement roof slab during the reverse construction stage. Therefore, in engineering projects, horizontal temporary support beams are often installed in open areas to solve such problems, while vertical support is achieved by adding temporary steel columns and piles. Although the above methods have certain applicability, the addition of steel columns and piles results in excessively dense column spacing in the area below the first basement level, which is not conducive to top-down excavation. At the same time, the addition of steel columns and piles also increases the construction cost, and the temporary columns and piles will be removed or abandoned after the basement top-down construction is completed, causing further waste and hindering the green and low-carbon control of top-down construction technology. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for temporarily extending and repositioning steel-concrete composite columns in reverse construction excavations. This method solves the problems of utilizing steel-concrete composite columns in situ when there are large open areas of the roof slab, such as atriums, and when the tops of structural columns are lowered, as well as the connection of beams and columns at different stages in reverse construction excavation projects. This technology can simultaneously meet the safety requirements of the temporary support beams and temporary extension columns in the open areas of the roof slab during the reverse excavation stage, the safety connection of the structural beams and structural columns at the original design column top positions, and the connection requirements of the structural beams and structural columns after the temporary extension columns are removed and the column tops are repositioned following the completion of the basement reverse construction.

[0004] The technical solution of this invention is: a method for temporarily extending and repositioning a steel-concrete composite column in a reverse-construction foundation pit, characterized by the following construction steps: S1, Pre-embedding of temporary and permanent nodes during the reverse excavation stage The top of the original steel-concrete composite column was extended to create a temporary extended section of the steel-concrete composite column. This temporary extended section of the steel-concrete composite column was then assembled and connected with a temporary support beam and a temporary concrete ring beam to form a temporary beam-column connection node at the top.

[0005] After the foundation pit is excavated in reverse to below the top elevation of the original steel-concrete composite column, the top of the original steel-concrete composite column is formed and connected to the concrete ring beam and structural beam to form a permanent beam-column connection structure. At the same time, sealing steel bars are pre-embedded in the concrete ring beam; some of the sealing steel bars are exposed upwards outside the concrete ring beam.

[0006] S2. Temporary structure dismantling and column top repositioning. After all the reverse construction procedures of the basement are completed, the temporary support beams, temporary concrete ring beams, and temporary extension steel-concrete columns are removed in sequence. Stiffening ring plates are welded to the top of the original steel-concrete columns that are exposed after removal. The pre-embedded sealing steel bars are bent and welded together to form the column cap steel cage at the top of the original steel-concrete columns. Then, water-swellable waterstop strips are installed inside the column cap steel cage and on the upper surface of the concrete ring beam. Finally, the concrete column cap is poured to cover the top of the original steel-concrete columns that are exposed after removal. The final beam-column connection node is formed and repositioned.

[0007] S3, Finishing construction of surface sealing layer After the column cap concrete has cured and the construction quality has passed inspection, the building surface layer is constructed in accordance with the building design specifications to cover the column cap, thus completing the final construction.

[0008] Based on the above technical features, in step S1, the original steel-concrete composite column and the temporary extension steel-concrete composite column are integrated as a whole. The original steel-concrete composite column and the extension steel-concrete composite column share the same extended steel pipe, and concrete is poured inside the steel pipe.

[0009] Based on the above technical features, in step S1, the top elevation of the temporary extension section of the steel-concrete composite column is lower than the beam surface elevation of the temporary support beam and the temporary concrete ring beam; a stiffening ring plate is welded to the top of the temporary extension section of the steel-concrete composite column, and shear studs and shear ring bars are welded to the sides; the main reinforcement bars on the top surface of the temporary support beam are installed through the top of the column, and the main reinforcement bars on the bottom surface of the temporary support beam are anchored into the temporary concrete ring beam.

[0010] Based on the above technical features, in step S1, shear studs and shear ring bars are welded to the sides of the original steel-concrete composite column, and the top and bottom main bars of the structural beam are anchored into the concrete ring beam.

[0011] This patent proposes a method for temporarily extending and repositioning steel-concrete composite columns in a reverse-construction foundation pit. On the one hand, by temporarily extending the steel-concrete composite columns whose tops have been lowered, it satisfies the vertical support requirements of the horizontal support beams and slabs at the top of open areas such as the atrium during the reverse-construction excavation stage, and makes full use of the original pile and column system of the frame columns, avoiding the need to add additional temporary columns and column piles, thus improving economy, facilitating construction, and avoiding waste. On the other hand, by reserving sealing steel bars in the concrete ring beam, setting column caps and waterstops on the repositioned column tops, it solves the problem of beam-column connection structure after the basement reverse construction is completed and the temporary extension column is removed.

[0012] The beneficial effects of this invention are as follows: by temporarily raising the steel-concrete composite column whose top has fallen, and by adopting a series of measures such as concrete ring beams, reserved sealing steel bars, and setting the repositioned pile top column cap, the requirements for beam-column connection during the reverse excavation stage of temporary horizontal support beams and structural beams, and the removal of temporary columns and repositioning of pile tops after the completion of reverse construction are solved. This method makes full use of the original structural piles and columns as vertical support components, avoids the need to add additional temporary columns and column piles, is convenient to construct, and is green and economical. Attached Figure Description

[0013] Figure 1 This is a structural elevation view of the steel-concrete composite column after temporary extension during the reverse excavation stage.

[0014] Figure 2 This is a schematic elevation view of the temporary extension steel columns removed after the basement reverse construction was completed.

[0015] Figure 3 This is a structural elevation view of the column cap after the top of the steel-concrete composite column has been reset.

[0016] Figure 4 This is a schematic diagram of the elevation of the column cap after it is completed and enclosed in the building surface.

[0017] Figure 5 This is a schematic diagram of the beam-column connection section after the steel-concrete composite column is temporarily extended during the reverse excavation stage.

[0018] Figure 6 This is a schematic diagram of the cross-section of the stiffening plate welded to the top of the temporary elevated steel column after its removal.

[0019] Figure 7 A schematic diagram of the column cap section installed on the top of the column after the temporary extension steel column is dismantled.

[0020] Figure 8 This is a schematic diagram showing the final state of the column caps being enclosed within the surface layer after the building surface layer is completed. Figure Labels

[0021] 1-Original design steel-concrete composite column; 2-Concrete ring beam; 3-Structural beam; 4-Shear stud; 5-Shear ring reinforcement; 6-Bottom main reinforcement of structural beam; 7-Top main reinforcement of structural beam; 8-Sealing reinforcement; 9-Temporary extension steel-concrete composite column; 10-Top main reinforcement of support beam; 11-Bottom main reinforcement of support beam; 12-Stiffening ring plate; 14-Water-swellable sealing strip; 15-Column capital; 16-Building surface layer; 17-Temporary concrete ring beam; 18-Temporary support beam. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] When the basement is a large, column-free space, such as an open atrium area, the top of the original steel-concrete composite column 1 falls below the elevation of the basement floor slab. The specific construction method for temporarily extending and repositioning the steel-concrete composite column in the reverse construction method excavation pit is as follows: Construction step S1 as follows Figure 1 and Figure 5 As shown, the top of the original steel-concrete composite column 1 is extended upwards to below the top surface of the temporary support beam 18, forming a temporary extended section of steel-concrete composite column 9. That is, the top elevation of the temporary extended section of steel-concrete composite column 9 is raised to the area of ​​the basement roof opening. The original steel-concrete composite column 1 and the temporary extended section of steel-concrete composite column 9 can share a single extended steel pipe, and concrete can be poured inside the steel pipe.

[0025] The top of the temporary elevated steel-concrete composite column 9 is welded with a stiffening ring plate 12, and the sides are welded with shear studs 4 and shear ring reinforcements 5, which are then connected to the temporary concrete ring beam 17. The main reinforcement 10 on the top surface of the support beam is installed through the top of the column, and the main reinforcement 11 on the bottom surface of the support beam is anchored into the temporary concrete ring beam 17, forming a beam-column connection structure at the top of the temporary elevated steel-concrete composite column.

[0026] After excavating in reverse to below the top of the original steel-concrete composite column 1, shear studs 4 and shear ring reinforcement 5 are welded to the side of the top of the original steel-concrete composite column 1 and then connected to the concrete ring beam 2. The top main reinforcement 7 and bottom main reinforcement 6 of the structural beam 3 are anchored into the concrete ring beam 2, forming the beam-column connection structure at the top of the original steel-concrete composite column 1. At the same time, sealing reinforcement 8 is pre-embedded in the concrete ring beam 2.

[0027] After the underground structure is constructed in reverse order, proceed to step S2. For example... Figure 2 , Figure 6 As shown, the upper temporary support beam 18, temporary concrete ring beam 17, and temporary extension steel-concrete column 9 are removed. The top elevation of the repositioned steel-concrete column should be 30mm to 50mm higher than the surface of the structural beams and slabs to avoid damaging the existing structure due to excessively low chisel surfaces during the removal of the temporary extension.

[0028] At the bottom of the temporary elevated steel-concrete composite column 9 after demolition, i.e., at the top of the original steel-concrete composite column 1, a stiffening ring plate 12 is welded. Afterwards, as... Figure 3 , Figure 7 As shown, the sealing reinforcement 8 is bent and welded. The sealing reinforcement 8 also serves as the vertical main reinforcement of the column cap, and after bending, it also serves as the top reinforcement of the column cap. The reinforcement area of ​​the sealing reinforcement is implemented in accordance with the requirements of the current concrete structure design code.

[0029] After installing the water-swellable sealing strip 14, the column cap 15 is poured to form the final beam-column connection structure after repositioning.

[0030] After step S2 is completed, proceed to step S3. For example... Figure 4 , Figure 8 As shown, the construction surface layer 16 is used to cover the column caps 15, completing the overall construction. The construction surface layer 16 is constructed using the same method as the surface layer in the basement atrium and other functional areas.

[0031] The basic concept of this invention is as follows: First, by fully utilizing the original structural pile and column system at the frame column positions, the originally designed low-lying steel-concrete composite columns are extended to form vertical supports for temporary support beams, thus avoiding the waste caused by adding additional temporary columns and column piles. Second, during the reverse construction excavation stage, the beam-column connections at each level are achieved mainly through measures such as setting concrete ring beams, shear studs, shear reinforcement rings, and stiffening ring plates. After the reverse construction is completed, the top temporary support beams and temporarily extended concrete columns are removed, and the tops of the originally designed steel-concrete composite columns are reset. After the column tops are reset, the pre-reserved sealing reinforcement bars in the concrete ring beam are bent and welded to form a column cap reinforcement cage. A water-swellable sealing strip is installed between the column cap and the concrete ring beam, and finally, the cap is poured to form the column top. After the column caps are formed, they are enclosed within the building surface layer during the subsequent construction stage, thus not affecting the final finished building surface.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for temporarily extending and repositioning a steel-concrete composite column in a reverse-construction foundation pit, characterized in that, The construction steps include the following: S1, Pre-embedding of temporary and permanent nodes during the reverse excavation stage The top of the original steel-concrete composite column (1) is extended to construct a temporary extended section steel-concrete composite column (9). The temporary extended section steel-concrete composite column (9) is assembled and connected with the temporary support beam (18) and the temporary concrete ring beam (17) to form a top temporary beam-column connection node. After the foundation pit is excavated to the top elevation of the original steel-concrete composite column (1), the top of the original steel-concrete composite column (1) is formed to connect with the concrete ring beam (2) and the structural beam (3) to form a permanent beam-column connection structure. At the same time, sealing steel bars (8) are pre-embedded in the concrete ring beam (2); some of the sealing steel bars (8) are exposed upward outside the concrete ring beam (2). S2. Temporary structure dismantling and column top repositioning. After all the reverse construction procedures of the basement are completed, the temporary support beam (18), the temporary concrete ring beam (17) and the temporary extension section steel pipe concrete column (9) are removed in sequence; a stiffening ring plate (12) is welded to the top of the original steel pipe concrete column (1) exposed after removal, and the pre-embedded sealing steel bars (8) are bent and welded together to form the column cap steel cage at the top of the original steel pipe concrete column (1). Then, a water-swellable waterstop strip (14) is set in the column cap steel cage and on the upper surface of the concrete ring beam (2). Then, the concrete column cap (15) is poured as a whole to cover the top of the original steel pipe concrete column (1) exposed after removal; the final beam-column connection node after molding and repositioning. S3, Finishing construction of surface sealing layer After the concrete of the column cap (15) has been cured and the construction quality has been accepted, the building surface layer (16) is constructed in accordance with the building design specifications to cover the column cap (15) and complete the final construction.

2. The method for temporary extension and repositioning of steel-concrete composite columns in a reverse-construction foundation pit according to claim 1, characterized in that: In step S1, the original steel-concrete composite column (1) and the temporary extension steel-concrete composite column (9) are a whole. The original steel-concrete composite column (1) and the extension steel-concrete composite column (9) share the same extended steel pipe, and concrete is poured in the steel pipe.

3. The implementation method for temporary extension and repositioning of steel-concrete composite columns in a reverse-construction foundation pit according to claim 1, characterized in that: In step S1, the top elevation of the temporary extension section steel pipe concrete column (9) is lower than the beam surface elevation of the temporary support beam (18) and the temporary concrete ring beam (17); the top of the temporary extension section steel pipe concrete column (9) is welded with a stiffening ring plate (12), and the sides are welded with shear studs (4) and shear ring bars (5); the main reinforcement bars (10) on the top surface of the support beam of the temporary support beam (18) are installed through the top of the column, and the main reinforcement bars (11) on the bottom surface of the support beam of the temporary support beam (18) are anchored into the temporary concrete ring beam (17).

4. The implementation method for temporary extension and repositioning of steel-concrete composite columns in a reverse-construction foundation pit according to claim 1, characterized in that: In step S1, shear studs (4) and shear ring bars (5) are welded to the side of the original steel-concrete composite column (1), and the top main bars (7) and bottom main bars (6) of the structural beam (3) are anchored into the concrete ring beam (2).

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