A reverse reinforced concrete structural column connection structure and construction method thereof

Abstract

A reverse construction reinforced concrete structure column connection structure and a construction method thereof, including a first construction structure, a second construction structure and a secondary pouring structure constructed in a soil layer, the first construction structure including a concrete cushion layer, an underground structure top plate, an early underground structure column cap, an early underground structure upper column, a prism-shaped cavity structure and a grouting steel pipe; the bottom of the grouting steel pipe is connected to the prism-shaped cavity structure to form a secondary grouting channel; the second construction structure includes an underground structure column cap, a temporary steel pipe support, a later underground structure lower column and a prism-shaped structure, and the secondary pouring structure is a sealing structure formed by grouting from a grouting steel pipe into the secondary grouting seam formed in the construction seam. The present invention combines the super-pouring method and the grouting method, and ensures the construction quality in the construction seam through the secondary pouring structure. Through the design of the prism-shaped cavity, the fitting connection between the two column structures is realized, the shear resistance of the connection part is increased, and the secondary pouring structure further reinforces the construction seam.

Description

Technical Field

[0001] The invention belongs to the field of reverse construction structural column construction, in particular to a reverse construction reinforced concrete structural column and a construction method thereof. Background Art

[0002] In the reverse construction method, the underground structure is divided into two parts: the early construction and the later construction. The early underground structure constructed first includes horizontal beams and the upper columns of the structural columns. Therefore, there is a construction joint between the lower columns of the later underground structure and the upper columns of the early structure. Due to the shrinkage of the concrete of the later underground structure columns, as well as defects such as water precipitation or accumulation of bubbles in the concrete on the joint surface, the construction quality of the construction joint and the effective force transmission between the upper and lower structural columns are greatly affected. This is a key issue that needs to be solved in the promotion and application of the reverse construction technology.

[0003] At present, in order to ensure the density of the horizontal joint concrete of the upper and lower structural columns, there are usually three treatment measures for the construction joints between the upper and lower columns of the reverse underground structure, namely, over-pouring, grouting and grouting. The over-pouring method is to pour concrete by pouring holes or bell mouths during the construction of the lower column of the underground structure in the later stage, so that the pouring surface of the lower column concrete exceeds a certain height of the construction joint. The over-pouring method is the most commonly used joint treatment process in reverse construction. It has the advantage of low cost, but it has high requirements for materials, operating processes, etc., and the construction quality is often not easy to guarantee.

[0004] Grouting is a construction method that uses high-flow, low-shrinkage grouting materials to treat joints during the later construction of the lower column of the underground structure. Grouting is usually used in conjunction with super-grouting, which is a further enhancement of the super-grouting method and an effective supplement to possible defects. It has a good effect on closing the cracks existing in the super-grouting method and improving the water-stopping performance, but it has no obvious effect on improving the stress performance of the connection position.

[0005] The grouting method is to reserve a gap of no less than 50mm between the lower column and the upper column during the later construction of the lower column of the underground structure. After the construction of the lower column is completed, a template is set up between the upper and lower sections, and high-strength, non-shrinkage grouting material is used to grout between the upper and lower column sections. The grouting method artificially turns one construction joint into two construction joints, and requires secondary formwork, which has a high construction cost. In addition, cement-based grouting materials have no aggregate components, and there is still a lack of a lot of application experience during construction.

[0006] For top-down underground structures, especially reinforced concrete structural columns, how to ensure the integrity and stress performance between the upper and lower columns, especially the shear resistance between the two, is a problem that the engineering community has been exploring. Summary of the invention

[0007] The purpose of the present invention is to provide a top-down reinforced concrete structural column connection structure and a construction method thereof, in order to solve the three existing construction methods for connecting construction joints between upper and lower columns of a top-down underground structure, wherein the super-pouring method has the advantages of simple construction and low cost, but has the technical problems of high requirements on the fluidity and operation process of concrete materials and difficult to guarantee the construction quality; the grouting method is often a further strengthening and supplement to the super-pouring method, and has a better effect on improving the water-stopping performance, but has the technical problem of little effect on improving the stress performance of the connection position, especially the shear resistance of the connection part; the grouting method has the advantages of high construction cost, and the cement-based grouting material for secondary pouring has no aggregate component, and the stress performance of the connection part, especially the high-strength structural column, is not easy to guarantee.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A top-down reinforced concrete structural column connection structure, comprising a pre-construction structure, a post-construction structure and a secondary casting structure constructed in a soil layer, wherein the pre-construction structure comprises a concrete cushion layer, an underground structure top plate, a pre-underground structure column cap, a pre-underground structure upper column, a prism-shaped cavity structure and a grouting steel pipe;

[0010] The concrete cushion layer is located on the upper side of the soil layer and the lower side of the top plate of the underground structure;

[0011] The underground structure top plate, the preliminary underground structure column caps and the preliminary underground structure upper column are an integrally cast reinforced concrete structure;

[0012] The prism-shaped cavity structure is located at the center of the upper column of the previous underground structure and is concave. The prism-shaped cavity structure is narrow at the top and wide at the bottom. It is a groove formed by pre-setting a customized prism body template box in the upper column of the previous underground structure and removing it. Two grouting steel pipes are fixedly connected to the top surface of the customized prism body template box to position and support steel bars. There are two grouting steel pipes in total. The bottom of the grouting steel pipe is positioned by sleeve-engaging with the top of the grouting steel pipe positioning support steel bars. The bottom surface of the grouting steel pipe is pressed tightly against the top surface of the customized prism body template box so that the bottom surface of the grouting steel pipe is flush with the top surface of the prism-shaped cavity structure; the top of the grouting steel pipe extends out of the top surface of the underground structure roof; the middle part of the grouting steel pipe is connected to the steel bars in the column cap of the underground structure by binding, and the bottom of the grouting steel pipe is connected to the prism-shaped cavity structure to form a secondary grouting channel;

[0013] The post-construction structure includes an underground structure column cap, a temporary steel pipe support, a later underground structure lower column and a prism-shaped structure. The underground structure column cap is excavated directly below the previous underground structure column cap. The underground structure column cap is a reinforced concrete structure. The top of the temporary steel pipe support is fixedly connected to the four corners of the previous underground structure column cap, and the bottom of the temporary steel pipe support is fixedly connected to the underground structure column cap.

[0014] The lower column of the later underground structure and the prism-shaped structure are reinforced concrete structures cast in one piece, the prism-shaped structure is located at the center of the top surface of the lower column of the later underground structure, the prism-shaped structure is narrow at the top and wide at the bottom, and is formed by filling the prism-shaped cavity structure with concrete; the lower column of the later underground structure is directly opposite to the upper column of the earlier underground structure, the bottom surface of the upper column of the earlier underground structure is connected to the top surface of the lower column of the later underground structure as a whole, and a construction joint is formed at the connection position of the two, and the construction joint is a bending surface at the prism-shaped structure position and a plane at other positions;

[0015] The secondary pouring structure is a sealing structure formed by grouting from a grouting steel pipe into the secondary grouting seam formed in the construction joint.

[0016] The column cap of the preliminary underground structure includes an upper horizontal plate body and a lower frustum body. The top of the temporary steel pipe support is supported on the bottom surface of the horizontal plate body. The frustum body is wide at the top and narrow at the bottom. The bottom surface size of the frustum body is the same as the size of the upper column of the preliminary underground structure, and the top surface size of the frustum body is smaller than the size of the horizontal plate body.

[0017] The steel bars in the underground structure column cap include the previous underground structure column cap main bars and the previous underground structure column cap stirrups;

[0018] The main reinforcement of the column cap of the early underground structure is arranged vertically downward from the top surface of the underground structure top plate and connected to the main reinforcement of the lower column of the later underground structure as a whole. The top of the main reinforcement of the column cap of the early underground structure is horizontally radially bent at the top surface of the underground structure top plate; the bottom of the main reinforcement of the column cap of the early underground structure passes through the bottom surface of the column cap of the underground structure, and the passing parts are arranged in a staggered manner, one long and one short.

[0019] The stirrups of the column cap of the preliminary underground structure are arranged within the height range of the column cap of the preliminary underground structure, and the stirrups of the column cap of the preliminary underground structure include half-ring stirrups alternately arranged at the front and rear sides, and the half-ring stirrups are tied and connected with the grouting steel pipe at the position of the grouting steel pipe.

[0020] The secondary cast structure is formed by slightly expansive cement slurry.

[0021] The two grouting steel pipes are the grouting pipe and the exhaust pipe respectively. The top surface of the grouting steel pipe is exposed 100mm-150mm above the top surface of the underground structure roof.

[0022] The height of the grouting steel pipe positioning support steel bars is 30mm-50mm, the diameter of the short plain round steel bars is 15mm-18mm, and the inner diameter of the grouting steel pipe is 16mm-20mm.

[0023] A construction method for a reverse reinforced concrete structural column connection structure, the construction steps are as follows:

[0024] Step 1: excavate the soil within the range of the top plate of the underground structure in the soil layer until the excavation reaches the elevation position of the bottom surface of the top plate of the underground structure;

[0025] Step 2: excavating the structure of the column cap and the upper column of the preliminary underground structure downward along the bottom surface of the top plate of the underground structure by manual excavation;

[0026] Step 3: Lay the preliminary underground structure column cap formwork, and drive elevation control wood piles at the joint turning point of the formwork panel, so that the top surface of the elevation control wood pile is flush with the bottom surface of the bottom formwork panel of the horizontal plate body;

[0027] Step 4: embed a customized prism formwork box at the bottom center of the upper column position of the previous underground structure, and weld a grouting steel pipe positioning support steel bar on the top of the customized prism formwork box;

[0028] Step 5: At this time, a concrete cushion is poured on the top surface of the soil layer, and the top surface of the concrete cushion is flush with the top surface of the previous underground structure column cap template;

[0029] Step 6: Tie up the steel bars of the underground structure top plate, the column caps of the preliminary underground structure and the steel bars of the upper columns of the preliminary underground structure, and insert the main bars of the column caps of the preliminary underground structure into the soil layer; then install two grouting steel pipes on the grouting steel pipe positioning support steel bars of the customized prism-shaped formwork box, insert the grouting steel pipe positioning support steel bars into the bottom of the grouting steel pipe, and tie up the middle of the grouting steel pipe with the hoop bars of the column caps of the preliminary underground structure; the top of the grouting steel pipe is exposed to the top surface of the underground structure top plate;

[0030] Step 7, pouring concrete of the underground structure top plate, the early underground structure column caps and the early underground structure upper column, then carrying out the waterproof layer construction of the underground structure top plate, and restoring the road on the upper side of the underground structure top plate;

[0031] Step 8: Continue to excavate the earth below the upper column of the previous underground structure, support the template of the underground structure column cap, tie the steel bars and cast;

[0032] Step nine, four temporary steel pipe supports are set between the underground structure column cap and the four corners of the horizontal plate body to bear the vertical load at the column position before the upper column of the early underground structure and the lower column of the later underground structure form an integral load-bearing column;

[0033] Step 10: remove the customized prism formwork box to form a prism-shaped cavity structure, then roughen the concrete at the bottom construction joint of the upper column of the previous underground structure and clean the steel bar stubble, and then mechanically connect the longitudinal main reinforcement of the upper column of the previous underground structure with the longitudinal main reinforcement of the lower column of the later underground structure;

[0034] Step eleven, supporting the lower column formwork reinforcement system of the lower column of the later underground structure, and leaving two overfilled trumpet formworks on both sides of the top for pouring concrete of the lower column of the later underground structure, the top surface of the overfilled trumpet formwork is higher than the top surface of the prism-shaped cavity structure, pouring concrete to form the lower column of the later underground structure and the prism-shaped structure, wherein the trumpet formwork positions on both sides of the column at the construction joint position are overfilled to form overfilled concrete;

[0035] Step 12: After the column strength meets the requirements, remove the temporary steel pipe support and the lower column formwork reinforcement system, and chisel out the over-cast concrete;

[0036] Step thirteen, secondary grouting is performed on the secondary grouting joints in the construction joints through two pre-buried grouting steel pipes, and the grouting liquid is injected from one of the grouting steel pipes until it overflows from the other grouting steel pipe, and the grouting is completed to form a sealing structure.

[0037] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0038] In the present invention, during the construction of the preliminary underground structure, a customized prism-shaped steel template is set at the bottom of the upper column of the preliminary structure, so as to ensure that a prism-shaped cavity structure can be formed at the bottom of the upper column of the preliminary construction. Therefore, by reserving a prism-shaped cavity structure in the upper column during the construction of the preliminary underground structure, a trumpet is set in the construction template of the lower column of the later underground structure to perform super-high pouring on the prism body, thereby forming a fitting mortise and tenon connection between the upper column of the preliminary underground structure and the lower column of the later underground structure.

[0039] The present invention welds short round steel bars with a height of 30mm-50mm and a diameter 2mm smaller than the inner diameter of the grouting pipe on the customized prism-shaped steel formwork, which serve as the lower support point and positioning point of the grouting steel pipe, thereby ensuring the fixed position of the grouting pipe in the early concrete pouring of the underground structure and the smooth grouting in the later stage.

[0040] The present invention sets two grouting steel pipes during the construction process of the upper column of the preliminary underground structure. The middle part of the grouting pipe is connected to the stirrups of the column cap of the preliminary underground structure, and the bottom is sleeved with the short round steel bar welded on the prism-shaped steel formwork, thereby ensuring the position of the grouting pipe in the preliminary underground structure concrete pouring and the smoothness of the subsequent grouting. After the reinforcement system of the formwork of the column of the later underground structure is removed, the grouting steel pipe is used to perform pressure grouting on the connection in the construction joint of the prism body position between the upper column poured in advance and the lower column poured in the later stage to form a secondary casting structure, thereby further ensuring the integrity and shear resistance of the upper and lower structural columns at the construction joint position. Two grouting steel pipes, one is used for pressure grouting of the gap at the connection part of the upper and lower column sections in the later stage, and the other is used for exhaust during the grouting process, thereby ensuring the density and quality of the grouting.

[0041] The present invention combines the super-pouring method and the grouting method, and ensures the construction quality in the construction joint through the secondary casting structure. Through the design of the prism-shaped cavity, the fitting connection between the two column structures is realized to form an approximate mortise and tenon connection. The construction joint is a bending surface, which improves the stress performance of the connection position, especially increases the shear resistance of the connection part. The secondary casting structure further reinforces the construction joint. The present invention designs a customized prism formwork box in the upper column in advance to form a prism-shaped cavity structure. At the same time, the prism-shaped cavity structure becomes the template for the subsequent lower column, reducing the cost of grouting construction and ensuring the stress performance of the connection part. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0043] Figure 1 It is a schematic diagram of the overall structure of the reverse-cast reinforced concrete structural column of the present invention.

[0044] Figure 2 It is a structural diagram of the upper columns of the preliminary underground structure.

[0045] Figure 3 It is a structural diagram of the lower column of the later underground structure.

[0046] Figure 4 It is a schematic diagram of the construction section of the upper column of the preliminary underground structure.

[0047] Figure 5 yes Figure 4 Schematic diagram of the structure of the customized prism template box.

[0048] Figure 6 It is the structural layout diagram of grouting steel pipes and preliminary underground structure column cap reinforcement.

[0049] Figure 7 yes Figure 6 Schematic diagram of the structure after horizontal rotation of 90 degrees.

[0050] Figure 8 yes Figure 6 and Figure 7 Schematic diagram of the top view structure.

[0051] Fig. 9 yes Figures 6 to 8 Schematic diagram of the three-dimensional structure.

[0052] Fig.10 It is a structural diagram of the formwork reinforcement system for casting columns in the lower section of the later underground structure.

[0053] Figure numerals: 1 - top plate of underground structure, 2 - column cap of preliminary underground structure, 2a - horizontal plate body, 2b - lower frustum body, 3 - upper column of preliminary underground structure, 4 - prism-shaped cavity structure, 5 - prism-shaped structure, 6 - lower column of later underground structure, 7 - column cap of underground structure, 8 - construction joint, 9 - temporary steel pipe support, 10 - concrete cushion layer, 11 - elevation control wooden pile, 12 - formwork of column cap of preliminary underground structure, 13 - grouting steel pipe positioning support steel bar, 14 - customized prism formwork box, 15 - soil layer, 16 - main reinforcement of column cap of preliminary underground structure, 17 - grouting steel pipe, 18 - stirrups of column cap of preliminary underground structure, 19 - over-grouting trumpet formwork, 20 - reinforcement steel pipe, 21 - tension bolts, 22 - wooden beam. DETAILED DESCRIPTION

[0054] See Example Figure 1 As shown, a top-down reinforced concrete structural column connection structure includes a first-construction structure, a second-construction structure and a secondary casting structure constructed in a soil layer 15.

[0055] See also Figure 2 As shown, the pre-constructed structure includes a concrete cushion layer 10, an underground structure top plate 1, a preliminary underground structure column cap 2, a preliminary underground structure upper column 3, a prism-shaped cavity structure 4 and a grouting steel pipe 17.

[0056] The concrete cushion layer 10 is located on the upper side of the soil layer 15 and the bottom side of the underground structure top plate 1 .

[0057] The underground structure top plate 1, the preliminary underground structure column cap 2 and the preliminary underground structure upper column 3 are reinforced concrete structures cast in one piece.

[0058] In this embodiment, the column cap 2 of the preliminary underground structure includes an upper horizontal plate body 2a and a lower frustum body 2b. The top of the temporary steel pipe support 9 is supported on the bottom surface of the horizontal plate body 2a. The frustum body 2b is wide at the top and narrow at the bottom. The bottom surface size of the frustum body 2b is the same as the size of the upper column 3 of the preliminary underground structure, and the top surface size of the frustum body 2b is smaller than the size of the horizontal plate body 2a.

[0059] The prism-shaped cavity structure 4 is located in the center of the upper column 3 of the previous underground structure and is concave. The prism-shaped cavity structure 4 is narrow at the top and wide at the bottom. It is a groove formed by pre-setting a customized prism body template box 14 in the upper column 3 of the previous underground structure and removing it. Two grouting steel pipe positioning support steel bars 13 are fixedly connected to the top surface of the customized prism body template box 14. There are two grouting steel pipes 17 in total. The bottom of the grouting steel pipe 17 is positioned by sleeve-fitting with the top of the grouting steel pipe positioning support steel bar 13. The bottom surface of the grouting steel pipe 17 is tightly pressed against the top surface of the customized prism body template box 14 so that the bottom surface of the grouting steel pipe 17 is flush with the top surface of the prism-shaped cavity structure 4; the top of the grouting steel pipe 17 extends out of the top surface of the underground structure top plate 1; the middle part of the grouting steel pipe 17 is connected by binding with the steel bars in the column cap 2 of the underground structure, and the bottom of the grouting steel pipe 17 is connected to the prism-shaped cavity structure 4 to form a secondary grouting channel.

[0060] See also Figure 5 As shown, in this embodiment, the customized prism formwork box 14 is a steel formwork box with a top width of 150 mm, a bottom width of 300 mm, and a hollow interior. The grouting steel pipe positioning support steel bar 13 serves as the lower support point and positioning point of the grouting steel pipe, thereby ensuring the position fixation of the grouting steel pipe in the early underground structure concrete pouring and the smoothness of the later grouting.

[0061] The height of the grouting steel pipe positioning support steel bar 13 is 30mm-50mm, and the diameter is a short round steel bar of 15mm-18mm, which is welded to the customized prism formwork box 14. The inner diameter of the grouting steel pipe 17 is 16mm-20mm. The two grouting steel pipes 17 are the grouting pipe and the exhaust pipe respectively. In order to facilitate grouting, the top surface of the grouting steel pipe 17 is exposed 100mm-150mm from the top surface of the underground structure top plate 1. In this embodiment, the diameter of the grouting steel pipe positioning support steel bar 13 is 18mm. The inner diameter of the grouting steel pipe is 20mm.

[0062] See also Figure 6-9 As shown, the steel bars in the column cap 2 of the underground structure include the main reinforcement 16 of the column cap of the early underground structure and the stirrups 18 of the column cap of the early underground structure. The main reinforcement 16 of the column cap of the early underground structure is arranged vertically downward from the top surface of the underground structure top plate 1 and is connected to the main reinforcement of the lower column 6 of the later underground structure as a whole. The top of the main reinforcement 16 of the column cap of the early underground structure is horizontally radially bent at the top surface position of the top plate 1 of the underground structure. The stirrups 18 of the column cap of the early underground structure are arranged within the height range of the column cap of the early underground structure 2. The stirrups 18 of the column cap of the early underground structure include semi-ring stirrups alternately arranged at intervals on the front and rear sides. The semi-ring stirrups are tied and connected with the grouting steel pipe 17 at the position of the grouting steel pipe 17. The bottom of the main reinforcement 16 of the column cap of the early underground structure passes through the bottom surface of the column cap of the underground structure 2, and the passing parts are arranged in a staggered manner, one long and one short, to form an arrangement form to avoid the weak points of force being on a line.

[0063] See also Figure 3 As shown, the post-construction structure includes an underground structure column cap 7, a temporary steel pipe support 9, a later underground structure lower section column 6 and a prism-shaped structure 5. The underground structure column cap 7 is excavated directly below the early underground structure column cap 2. The underground structure column cap 7 is a reinforced concrete structure. The top of the temporary steel pipe support 9 is fixedly connected to the four corners of the early underground structure column cap 2, and the bottom of the temporary steel pipe support 9 is fixedly connected to the underground structure column cap 7.

[0064] The lower column 6 of the later underground structure and the prism-shaped structure 5 are reinforced concrete structures cast as one piece. The prism-shaped structure 5 is located at the center of the top surface of the lower column 6 of the later underground structure. The prism-shaped structure 5 is narrow at the top and wide at the bottom, and is formed by filling the prism-shaped cavity structure 4 with concrete; the lower column 6 of the later underground structure is directly opposite to the upper column 3 of the earlier underground structure, and the bottom surface of the upper column 3 of the earlier underground structure is connected to the top surface of the lower column 6 of the later underground structure as a whole, and a construction joint 8 is formed at the connection position between the two, and the construction joint 8 is a bending surface at the position of the prism-shaped structure 5 and a plane at other positions.

[0065] The secondary cast structure is a sealing structure formed by grouting from a grouting steel pipe 17 into the secondary grouting seam formed in the construction seam 8. The secondary cast structure is formed by micro-expansion cement slurry.

[0066] The construction steps of this reverse construction reinforced concrete column connection structure are as follows:

[0067] Step 1: excavate the earth within the range of the underground structure top plate 1 in the soil layer 15 until the excavation reaches the bottom elevation position of the underground structure top plate 1.

[0068] Step 2: adopting the method of manual excavation, excavating downwards along the bottom surface of the underground structure top plate 1 to form the structural form of the preliminary underground structure column cap 2 and the preliminary underground structure upper column 3.

[0069] Step three, lay the preliminary underground structure column cap formwork 12, and drive elevation control piles 11 at the joint turning point of the formwork panel. The top surface of the elevation control piles 11 is flush with the bottom surface of the bottom formwork panel of the horizontal plate body 2a; in this embodiment, the structural column cap formwork 12 adopts 14mm thick laminated plywood.

[0070] Step 4: embed a customized prism formwork box 14 at the bottom center of the upper column 3 of the previous underground structure, and a grouting steel pipe positioning support steel bar 13 is welded on the top of the customized prism formwork box 14.

[0071] Step 5: At this time, a concrete cushion layer 10 is poured on the top surface of the soil layer 15. The top surface of the concrete cushion layer 10 is flush with the top surface of the previous underground structure column cap template 12. The thickness of the concrete cushion layer 10 is 100mm, and the concrete grade is C15. The concrete cushion layer 10 ensures the flatness of the bottom concrete surface of the underground structure top plate 1. After the construction is completed, refer to Figure 4 shown.

[0072] Step six, tie up the steel bars of the underground structure top plate 1, the preliminary underground structure column caps 2 and the preliminary underground structure upper column 3, and insert the preliminary underground structure column cap main reinforcement 16 into the soil layer 15; then install two grouting steel pipes 17 on the grouting steel pipe positioning support reinforcement 13 of the customized prism-shaped template box 14, insert the grouting steel pipe positioning support reinforcement 13 into the bottom of the grouting steel pipe 17, and the middle part of the grouting steel pipe 17 is tied and connected with the preliminary underground structure column cap stirrups 18; the top of the grouting steel pipe 17 is exposed from the top surface of the underground structure top plate 1.

[0073] Step seven, pouring concrete of the underground structure top plate 1, the preliminary underground structure column caps 2 and the preliminary underground structure upper column 3, then constructing the waterproof layer of the underground structure top plate 1, and restoring the road on the upper side of the underground structure top plate 1.

[0074] Step eight, continue to excavate the earth below the upper column 3 of the previous underground structure, support the template of the underground structure column cap 7, tie the steel bars and cast.

[0075] Step nine, four temporary steel pipe supports 9 are set between the underground structure column pedestal 7 and the four corners of the horizontal plate body 2a to bear the vertical load at the column position before the early underground structure upper column 3 and the later underground structure lower column 6 form an integral load-bearing column.

[0076] Step ten, remove the customized prism formwork box 14 to form a prism-shaped cavity structure 4, then roughen the concrete at the bottom construction joint 8 of the upper column 3 of the previous underground structure and clean the steel bar stubble, and then mechanically connect the longitudinal main reinforcement of the upper column 3 of the previous underground structure with the longitudinal main reinforcement of the lower column 6 of the later underground structure.

[0077] Step 11, see Fig.10 As shown, the lower column formwork reinforcement system of the lower column 6 of the later underground structure is supported, and two over-filled trumpet formworks 19 are left on both sides of the top for pouring concrete of the lower column 6 of the later underground structure. The top surface of the over-filled trumpet formwork 19 is higher than the top surface of the prism-shaped cavity structure 4, and concrete is poured to form the lower column 6 and the prism-shaped structure 5 of the later underground structure, wherein the over-filled trumpet formworks 19 on both sides of the column at the construction joint 8 form over-filled concrete; to ensure the density of the pouring, the top surface of the over-filled trumpet formwork 19 needs to be 200 mm higher than the top surface of the prism-shaped cavity structure 4.

[0078] Step 12: After the column strength meets the requirements, the temporary steel pipe support 9 and the lower column formwork reinforcement system are removed, and the excess over-cast concrete outside the column is chiseled off. In this embodiment, the lower column formwork reinforcement system includes a reinforcement steel pipe 20, a tension bolt 21 and a wooden beam 22.

[0079] Step 13: When pouring the lower column 6 of the underground structure in the later stage, the concrete may not be able to completely fill the prism-shaped cavity structure 4 in the upper column 3 of the previous underground structure, resulting in a loose connection between the upper and lower structural columns. Therefore, the secondary grouting seams in the construction joint 8 are secondary grouting through two pre-buried grouting steel pipes 17, and the grouting material is micro-expansion cement slurry. The grouting liquid is injected from one of the grouting steel pipes until it overflows from the other grouting steel pipe, and the grouting is completed to form a sealed structure.

Claims

1. A top-down reinforced concrete column connection structure, characterized in that: It comprises a pre-construction structure, a post-construction structure and a secondary casting structure constructed in a soil layer (15), wherein the pre-construction structure comprises a concrete cushion layer (10), an underground structure top plate (1), a pre-underground structure column cap (2), a pre-underground structure upper column (3), a prism-shaped cavity structure (4) and a grouting steel pipe (17); The concrete cushion layer (10) is located on the upper side of the soil layer (15) and on the lower side of the underground structure top plate (1); The underground structure top plate (1), the preliminary underground structure column cap (2) and the preliminary underground structure upper column (3) are an integrally cast reinforced concrete structure; The prism-shaped cavity structure (4) is located at the center of the upper column (3) of the previous underground structure and is concave. The prism-shaped cavity structure (4) is narrow at the top and wide at the bottom. It is a groove formed by removing a custom prism-shaped template box (14) preset in the upper column (3) of the previous underground structure. Two grouting steel pipe positioning support steel bars (13) are fixedly connected to the top surface of the custom prism-shaped template box (14). There are two grouting steel pipes (17) in total. The bottom of the grouting steel pipe (17) is connected to the grouting steel pipe positioning support steel bars (13). The top of the supporting steel bar (13) is sleeved and positioned, and the bottom surface of the grouting steel pipe (17) is pressed against the top surface of the customized prism-shaped formwork box (14) so ​​that the bottom surface of the grouting steel pipe (17) is flush with the top surface of the prism-shaped cavity structure (4); the top of the grouting steel pipe (17) extends out of the top surface of the underground structure top plate (1); the middle part of the grouting steel pipe (17) is tied and connected with the steel bars in the column cap (2) of the underground structure, and the bottom of the grouting steel pipe (17) is connected to the prism-shaped cavity structure (4) to form a secondary grouting channel; The post-construction structure comprises an underground structure column cap (7), a temporary steel pipe support (9), a later underground structure lower column (6) and a prism-shaped structure (5); the underground structure column cap (7) is excavated directly below the earlier underground structure column cap (2); the underground structure column cap (7) is a reinforced concrete structure; the top of the temporary steel pipe support (9) is fixedly connected to the four corners of the earlier underground structure column cap (2); the bottom of the temporary steel pipe support (9) is fixedly connected to the underground structure column cap (7); The lower column (6) of the later underground structure and the prism-shaped structure (5) are reinforced concrete structures cast in one piece. The prism-shaped structure (5) is located at the center of the top surface of the lower column (6) of the later underground structure. The prism-shaped structure (5) is narrow at the top and wide at the bottom. It is formed by filling the prism-shaped cavity structure (4) with concrete. The lower column (6) of the later underground structure is directly opposite to the upper column (3) of the earlier underground structure. The bottom surface of the upper column (3) of the earlier underground structure is connected to the top surface of the lower column (6) of the later underground structure as a whole. A construction joint (8) is formed at the connection position of the two. The construction joint (8) is a bending surface at the position of the prism-shaped structure (5) and a flat surface at other positions. The secondary pouring structure is a sealing structure formed by grouting from a grouting steel pipe (17) into a secondary grouting joint formed in a construction joint (8).

2. The top-down reinforced concrete structural column connection structure according to claim 1 is characterized in that: The column cap (2) of the preliminary underground structure comprises an upper horizontal plate body (2a) and a lower frustum body (2b), the top of the temporary steel pipe support (9) is supported on the bottom surface of the horizontal plate body (2a), the frustum body (2b) is wide at the top and narrow at the bottom, the bottom surface size of the frustum body (2b) is the same as the size of the upper column (3) of the preliminary underground structure, and the top surface size of the frustum body (2b) is smaller than the size of the horizontal plate body (2a).

3. The top-down reinforced concrete structural column connection structure according to claim 2 is characterized in that: The steel bars in the underground structure column cap (2) include the previous underground structure column cap main bars (16) and the previous underground structure column cap stirrups (18); The main reinforcement bars (16) of the column caps of the early underground structure are arranged vertically downward from the top surface of the underground structure top plate (1) and are connected to the main reinforcement bars of the lower column (6) of the later underground structure as a whole. The top of the main reinforcement bars (16) of the column caps of the early underground structure is horizontally radially bent at the top surface of the underground structure top plate (1). The bottom of the main reinforcement bars (16) of the column caps of the early underground structure passes through the bottom surface of the column caps (2) of the underground structure, and the passing parts are arranged in a staggered manner, one long and one short. The preliminary underground structure column cap stirrups (18) are arranged within the height range of the preliminary underground structure column cap (2), and the preliminary underground structure column cap stirrups (18) include semi-ring stirrups arranged alternately at the front and rear sides, and the semi-ring stirrups are tied and connected to the grouting steel pipe (17) at the position of the grouting steel pipe (17).

4. The top-down reinforced concrete structural column connection structure according to claim 2 is characterized in that: The secondary cast structure is formed by slightly expansive cement slurry.

5. The reverse reinforced concrete structural column connection structure according to claim 2 is characterized in that: The two grouting steel pipes (17) are respectively a grouting inlet pipe and an exhaust pipe. The top surface of the grouting steel pipe (17) is exposed 100 mm to 150 mm above the top surface of the underground structure top plate (1).

6. The top-down reinforced concrete structural column connection structure according to claim 2 is characterized in that: The height of the grouting steel pipe positioning support steel bars is 30mm-50mm, the diameter of the short round steel bars is 15mm-18mm, and the inner diameter of the grouting steel pipe (17) is 16mm-20mm.

7. A construction method for a top-down reinforced concrete structural column connection structure according to any one of claims 2 to 6, characterized in that: The construction steps are as follows: Step 1: excavating earth within the range of the underground structure top plate (1) in the soil layer (15) until the excavation reaches the bottom elevation of the underground structure top plate (1); Step 2: excavating the structure of the column cap (2) and the upper column (3) of the preliminary underground structure downwards along the bottom surface of the underground structure top plate (1) by manual excavation; Step 3, laying the preliminary underground structure column cap formwork (12), and driving elevation control wood piles (11) at the joint turning point of the formwork panel, wherein the top surface of the elevation control wood pile (11) is flush with the bottom surface of the bottom formwork panel of the horizontal plate body (2a); Step 4: embed a custom prism formwork box (14) at the bottom center of the upper column (3) of the previous underground structure, and weld a grouting steel pipe positioning support steel bar (13) on the top of the custom prism formwork box (14); Step 5: at this time, a concrete cushion layer (10) is poured on the top surface of the soil layer (15), and the top surface of the concrete cushion layer (10) is flush with the top surface of the previous underground structure column cap template (12); Step 6: Tie up the steel bars of the underground structure top plate (1), the column caps (2) of the preliminary underground structure, and the steel bars of the upper column (3) of the preliminary underground structure, and insert the main bars (16) of the column caps of the preliminary underground structure into the soil layer (15); then install two grouting steel pipes (17) on the grouting steel pipe positioning support bars (13) of the customized prism-shaped template box (14), insert the grouting steel pipe positioning support bars (13) into the bottom of the grouting steel pipe (17), and tie up the middle of the grouting steel pipe (17) with the stirrups (18) of the column caps of the preliminary underground structure; the top of the grouting steel pipe (17) is exposed from the top surface of the underground structure top plate (1); Step 7, pouring concrete of the underground structure top plate (1), the preliminary underground structure column cap (2) and the preliminary underground structure upper column (3), then constructing a waterproof layer of the underground structure top plate (1), and restoring the road on the upper side of the underground structure top plate (1); Step eight, continue to excavate the earth below the upper column (3) of the previous underground structure, support the template of the underground structure column cap (7), tie the steel bars and cast; Step nine, four temporary steel pipe supports (9) are arranged between the underground structure column cap (7) and the four corners of the horizontal plate body (2a) to bear the vertical load at the column position before the upper column (3) of the early underground structure and the lower column (6) of the later underground structure form an integral load-bearing column; Step 10, removing the customized prism formwork box (14) to form a prism-shaped cavity structure (4), then roughening the concrete at the bottom construction joint (8) of the upper column (3) of the previous underground structure and cleaning the steel bar stubble, and then mechanically connecting the longitudinal main reinforcement of the upper column (3) of the previous underground structure with the longitudinal main reinforcement of the lower column (6) of the later underground structure; Step eleven, supporting the lower column formwork reinforcement system of the lower column (6) of the later underground structure, and leaving two overfilled trumpet formworks (19) on both sides of the top for pouring concrete of the lower column (6) of the later underground structure, the top surface of the overfilled trumpet formworks (19) being higher than the top surface of the prism-shaped cavity structure (4), pouring concrete to form the lower column (6) of the later underground structure and the prism-shaped structure (5), wherein the overfilled trumpet formworks (19) on both sides of the column at the construction joint (8) position form overfilled concrete; Step 12: After the column strength meets the requirements, the temporary steel pipe support (9) and the lower column formwork reinforcement system are removed, and the over-filled concrete is chiseled out; Step thirteen, secondary grouting is performed on the secondary grouting joint in the construction joint (8) through two pre-buried grouting steel pipes (17), and the grouting liquid is injected from one of the grouting steel pipes until it overflows from the other grouting steel pipe, and the grouting is completed to form a sealed structure.

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