Underground structure prefabricated column foot assembly type connecting structure and construction method

Abstract

The invention discloses an underground structure prefabricated column base assembly type connecting structure and a construction method, and high-precision positioning and efficient force transmission of a prefabricated column are achieved through an anchor bolt pre-embedding and corrugated pipe grouting technology. The structure comprises a bottom longitudinal beam pre-embedded assembly, a prefabricated column connecting steel plate and a stiffening rib, and is fixed through anchor bolts and reinforced through grouting during construction, so that the joint mechanical property and the construction efficiency are remarkably improved. The problems that a traditional column base is difficult to connect and position, low in force transmission efficiency, complex in construction and the like are effectively solved, the method has the advantages of being convenient to position and construct, reliable in load transmission and the like, the mechanical property and construction efficiency of a column base joint are remarkably improved, and the method is suitable for rail transit fabricated underground stations and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of column foot connection of prefabricated underground structures such as underground stations in rail transit engineering, and particularly relates to a prefabricated connection structure and construction method for the column foot of a precast column of an underground structure. Background Art

[0002] With the rapid development of urban rail transit construction, prefabricated underground structures have gradually attracted attention due to their advantages such as high efficiency and environmental protection. In prefabricated underground structures, the column foot is a key part that bears the loads of the top slab and the middle slab, and its mechanical safety performance and construction quality are directly related to the stability and construction efficiency of the entire underground structure. However, at present, the design of prefabricated underground structures is still in its infancy, and the column foot connection technology is not yet mature. The existing column foot connection methods have many deficiencies in terms of mechanical properties and construction convenience, and it is difficult to meet the growing engineering requirements. Therefore, it is urgent to develop a column foot connection and construction method suitable for prefabricated underground structures. However, the existing prefabricated column foot connection technology still has the following problems: Difficult positioning: Traditional column foot connections rely on on-site welding or pouring, resulting in difficult to guarantee the positioning accuracy of precast columns and bottom longitudinal beams, which affects the overall stability of the structure.

[0003] Low force transfer efficiency: The design of the column foot joint is unreasonable, resulting in the inability to effectively transfer the main reinforcement load to the bottom longitudinal beam, and there is a risk of local stress concentration.

[0004] Complex construction: The existing technology requires multiple adjustments and temporary fixings, with a long construction period and high labor costs.

[0005] For example, Patent CN201810123456.7 proposed an anchor bolt structure for connecting a precast column and a foundation, but it did not solve the problem of coordinated force transfer between corrugated pipe grouting and steel reinforcement cage; the literature "Design and Construction of Prefabricated Underground Structures" also pointed out that the grouting density of existing column foot connection joints is insufficient, which is likely to lead to a decline in durability.

[0006] Based on this, the present invention proposes an innovative prefabricated connection structure and construction method, which significantly improves the mechanical properties and construction efficiency of the column foot joint through the technologies of embedded anchor bolts, welded connection plates, and corrugated pipe grouting. Summary of the Invention

[0007] The present invention aims to provide a prefabricated connection and construction method for the column foot of a precast column of an underground structure, which realizes the efficient installation and construction of the column foot joint on the premise of ensuring good mechanical properties of the column foot of the prefabricated underground structure, and solves the design and related construction problems of the column foot of the prefabricated underground structure.

[0008] To achieve the above object, the present invention provides a prefabricated connection structure for the column foot of a precast column of an underground structure, including: Bottom longitudinal beam 1, at the top of the bottom longitudinal beam 1, a bottom longitudinal beam anchor bolt base plate 4 and embedded anchor bolts 3 are pre-buried, and a bottom longitudinal beam reserved insertion bar 10 is pre-buried at the center of the bottom longitudinal beam 1; Prefabricated column 6, at the bottom of the prefabricated column 6, a prefabricated column anchor bolt base plate 5 is provided, and the prefabricated column anchor bolt base plate 5 is connected to the bottom longitudinal beam anchor bolt base plate 4 through the embedded anchor bolts 3; the prefabricated column 6 includes prefabricated column main reinforcement bars 7 and a connecting steel plate 11, the prefabricated column main reinforcement bars 7 are welded to the connecting steel plate 11, and the connecting steel plate 11 is welded to the prefabricated column anchor bolt base plate 5; connection holes are opened at the positions of the bottom longitudinal beam anchor bolt base plate 4 corresponding to the positions of the bottom longitudinal beam embedded anchor bolts 3; Corrugated pipe 9 and grouting holes 8, the corrugated pipe 9 and the grouting holes 8 are pre-buried at the center of the bottom of the prefabricated column 6, the bottom longitudinal beam reserved insertion bar 10 is inserted into the corrugated pipe 9, the positions of the corrugated pipe 9 and the bottom longitudinal beam reserved insertion bar 10 correspond one by one, and high-strength grouting material is injected through the grouting holes 8.

[0009] Furthermore, the connecting steel plate 11 is provided with stiffening ribs 12, and the stiffening ribs 12 are connected to the prefabricated column anchor bolt base plate 5 by double-sided fillet welds.

[0010] Furthermore, bottom longitudinal beam main reinforcement bars 18 and anchor bolt positioning frames 2 are also pre-buried on the bottom longitudinal beam 1.

[0011] Furthermore, the prefabricated column anchor bolt base plate 5 of the prefabricated column 6 is connected to the bottom longitudinal beam anchor bolt base plate 4 through double nuts 13 and anchor bolt backing plates 16.

[0012] Furthermore, the connecting steel plate 11 is connected to the prefabricated column anchor bolt base plate 5 by full penetration groove welding, and the stiffening ribs 12 are welded to the connecting steel plate 11 and the prefabricated column anchor bolt base plate 5 by double-sided fillet welds.

[0013] The present invention also provides a construction method for assembling and connecting the column foot of a prefabricated column in an underground structure, including the following steps: Step 1: First, bind the bottom longitudinal beam main reinforcement bars 18; pre-bury the bottom longitudinal beam anchor bolt base plate 4 at the top of the bottom longitudinal beam; at the same time, pre-bury the anchor bolt positioning frame 2 in the bottom longitudinal beam, and pre-bury the anchor bolts 3, and set the bottom longitudinal beam reserved insertion bar 10 and pre-buried steel bar stirrups 19 in the bottom longitudinal beam; Step 2: Complete the pouring of the stacked prefabricated column 6 in the factory. The prefabricated column 6 is pre-buried with a corrugated pipe 9, prefabricated column main reinforcement bars 7 and a connecting steel plate 11. At the same time, grouting holes 8 are provided on the prefabricated column 6, and a prefabricated column anchor bolt base plate 5 is provided at the bottom of the prefabricated column 6. The prefabricated column main reinforcement bars 7 are welded to the connecting steel plate 11, the connecting steel plate 11 is welded to the prefabricated column anchor bolt base plate 5, the connecting steel plate 11 is welded with stiffening ribs 12 and stud bolts 15, and holes are opened at the corresponding positions of the prefabricated column anchor bolt base plate 5. The positions of the corrugated pipe 9 and the bottom longitudinal beam reserved insertion bar 10 correspond one by one; Step 3: Clean the contact surfaces of the embedded bolt base plate 5 of the precast column and the embedded bolt base plate 4 of the bottom longitudinal beam. Insert the embedded bolts 3 of the bottom longitudinal beam into the openings of the embedded bolt base plate at the bottom of the precast column. Insert the reserved reinforcing bars 10 of the bottom longitudinal beam into the embedded corrugated pipe 9 of the precast column. Install the bolt backing plates 16 and double nuts 13 in sequence and tighten them. Weld the bolt backing plates 16 and the embedded bolt base plate 5 of the precast column around the perimeter. Full-weld the embedded bolt base plate 5 of the precast column and the embedded bolt base plate 4 of the bottom longitudinal beam. Pour high-strength grouting material into the corrugated pipe 9 through the grouting hole 8. Pour the reserved reinforcing bars 10 of the bottom longitudinal beam into the precast column 6. At the same time, pour the concrete at the column foot to isolate the embedded bolt base plate 5 of the precast column and the embedded bolt base plate 4 of the bottom longitudinal beam from the air.

[0014] Further, in Step 1, after the binding of the main reinforcement bars 18 of the bottom longitudinal beam is completed, it is necessary to check the steel bar specifications, spacing, and binding firmness. After meeting the design requirements, proceed with the subsequent embedding work.

[0015] Further, in Step 2, when welding the main reinforcement bars of the precast column and the connecting steel plate, control the welding current, voltage, and welding speed to ensure the welding quality. After welding, perform non-destructive testing.

[0016] Further, in Step 3, before grouting, check the sealing performance of the corrugated pipe to ensure there is no grout leakage. During the grouting process, control the grouting pressure and grouting volume to ensure that the corrugated pipe is fully grouted.

[0017] Further, in Step 3, after the concrete at the column foot is poured, carry out curing according to regulations. The curing time meets the design and specification requirements to ensure the growth of concrete strength.

[0018] In the present invention, by providing embedded bolt base plates for the bottom longitudinal beam and the precast column and using bolts for connection, the positioning and construction process of the precast column are simplified. The fabrication of the precast column and the construction preparation of the bottom longitudinal beam can be carried out simultaneously, reducing the on-site construction time. During connection, insert the embedded bolts into the holes of the embedded bolt base plate of the precast column, which is simple in operation and improves the construction efficiency.

[0019] The bolts around the column foot and the reserved steel cage in the middle work together. The main reinforcement bars of the precast column are connected to the connecting steel plate by welding, and the connecting steel plate is then welded to the embedded bolt base plate. The load is transmitted to the embedded bolt base plate of the bottom longitudinal beam through the bolts. At the same time, the reserved reinforcing bars of the bottom longitudinal beam are inserted into the corrugated pipe of the precast column and grouted, enhancing the connection integrity, effectively ensuring the transfer of the precast column load to the bottom longitudinal beam, and ensuring the mechanical properties and stability of the underground structure.

[0020] The stiffeners enhance the stability of the connecting steel plate and the embedded bolt base plate, preventing deformation under load. The embedded steel bar stirrups restrain the concrete of the bottom longitudinal beam, preventing cracking. The stud bolts enhance the bonding force between the connecting steel plate and the concrete, enabling better cooperation of each component and improving the stability of the entire structure. Description of the Drawings

[0021] Figure 1It is a schematic diagram of the connection of the column bottom node.

[0022] Figure 2 It is a top view of the column bottom node.

[0023] Figure 3 It is a detailed drawing of the anchor bolts.

[0024] Reference numerals: 1-bottom longitudinal beam; 2-anchor bolt positioning frame; 3-embedded anchor bolt; 4-bottom longitudinal beam anchor bolt base plate; 5-prefabricated column anchor bolt base plate; 6-prefabricated column; 7-prefabricated column main reinforcement; 8-grouting hole; 9-corrugated pipe; 10-bottom longitudinal beam reserved inserted reinforcement; 11-steel bar connection steel plate; 12-stiffening rib; 13-double nut; 14-column footing cast-in-place concrete; 15-stud; 16-anchor bolt backing plate; 17-opening in the anchor bolt base plate; 18-bottom longitudinal beam main reinforcement; 19-embedded steel bar stirrup; 20-embedded corrugated pipe stirrup. Specific embodiments

[0025] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0026] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups.

[0027] For the sake of simplicity of the drawings, only the parts related to the present invention are schematically shown in each drawing, and they do not represent their actual structures as products. In addition, for the sake of simplicity and easy understanding of the drawings, in some drawings, components with the same structure or function are only schematically shown for one of them, or only one of them is marked. In this article, "one" not only means "only this one", but also can mean the situation of "more than one".

[0028] It should be further understood that the term "and / or" used in the specification and appended claims of this application refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0029] In the embodiments shown in the drawings, the indication of directions (such as up, down, left, right, front and back) is used to explain that the structures and movements of various components of the present invention are not absolute but relative. When these components are in the positions shown in the drawings, these explanations are appropriate. If the description of the positions of these components changes, then the indication of these directions also changes accordingly.

[0030] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0032] This embodiment describes in detail an assembled connection structure and construction method for the prefabricated column foot of an underground structure, aiming to improve the mechanical properties and construction efficiency of the assembled underground structure foot. Figure 1 - Figure 3 ) provide detailed description of the specific implementation process.

[0033] Example 1

[0034] See also Figures 1-3 The present embodiment provides an assembled connection structure of the column foot of an underground structure prefabricated column, comprising: a bottom longitudinal beam 1, wherein a bottom longitudinal beam anchor bottom plate 4 and a pre-embedded anchor bolt 3 are pre-embedded at the top of the bottom longitudinal beam 1, and a bottom longitudinal beam reserved dowel bar 10 is pre-embedded at the center of the bottom longitudinal beam 1; a prefabricated column 6, wherein a prefabricated column anchor bottom plate 5 is provided at the bottom of the prefabricated column 6, and the prefabricated column anchor bottom plate 5 is connected to the bottom longitudinal beam anchor bottom plate 4 through the pre-embedded anchor bolt 3; the prefabricated column 6 comprises a prefabricated column main reinforcement 7 and a connecting steel plate 11, The prefabricated column main reinforcement 7 is welded to the connecting steel plate 11, and the connecting steel plate 11 is welded to the prefabricated column anchor base plate 5; the bottom longitudinal beam anchor base plate 4 is provided with a connecting hole corresponding to the position of the bottom longitudinal beam embedded anchor 3; the corrugated pipe 9 and the grouting hole 8, the corrugated pipe 9 and the grouting hole 8 are embedded in the bottom center of the prefabricated column 6, the bottom longitudinal beam reserved dowel 10 is inserted into the corrugated pipe 9, the position of the corrugated pipe 9 and the bottom longitudinal beam reserved dowel 10 corresponds one by one, and high-strength grouting material is injected through the grouting hole 8.

[0035] As a preferred embodiment, the connecting steel plate 11 is provided with a stiffening rib 12, and the stiffening rib 12 is connected to the prefabricated column anchor bolt base plate 5 by a double-sided fillet weld.

[0036] As a preferred embodiment, the bottom longitudinal beam 1 is also pre-embedded with a bottom longitudinal beam main reinforcement 18 and an anchor bolt positioning frame 2 .

[0037] As a preferred embodiment, the precast column anchor base plate 5 of the precast column 6 is connected to the bottom longitudinal beam anchor base plate 4 through a double nut 13 and an anchor pad 16 .

[0038] As a preferred embodiment, the connecting steel plate 11 and the precast column anchor bolt base plate 5 are connected by full penetration groove welding, and the stiffening rib 12 and the connecting steel plate 11 and the precast column anchor bolt base plate 5 are welded by double-sided fillet welds.

[0039] Embodiment 2

[0040] This example provides a construction method for the assembled connection structure of the precast column footing of an underground structure, including the following specific steps: Step 1, Construction preparation of the bottom longitudinal beam 1. Main reinforcement binding First, carry out the construction preparation work of the bottom longitudinal beam 1, and bind the main reinforcement 18 of the bottom longitudinal beam according to the design requirements. During the binding process, strictly control the spacing, quantity, and firmness of the main reinforcement. Select steel bars that meet national standards as the main reinforcement to ensure that their strength and toughness meet the load-bearing requirements of the underground structure. For example, according to the design calculation, the bottom longitudinal beam bears a large load, so the diameter and material of the main reinforcement need to be accurately calculated and selected to ensure the safety of the structure. After binding, conduct a comprehensive inspection of the layout of the main reinforcement to ensure that it meets the requirements of the design drawings.

[0041] 2. Embedding of the anchor bolt base plate Embed the bottom longitudinal beam anchor bolt base plate 4 at the bottom of the bottom longitudinal beam. Before embedding, conduct a quality inspection of the anchor bolt base plate to ensure that its dimensional accuracy and surface flatness meet the requirements. Use a positioning die to assist in embedding to ensure the accurate position of the anchor bolt base plate. The material of the anchor bolt base plate is selected as high-strength steel to ensure that it can bear the load transmitted by the precast column. In this embodiment, the material of the anchor bolt base plate is Q345B steel, and its yield strength and tensile strength can meet the design requirements.

[0042] 3. Anchor bolt positioning and embedding Install the anchor bolt positioning frame 2, which is used to accurately determine the position of the anchor bolt 3. The anchor bolt positioning frame is welded by angle steel or channel steel and has sufficient stiffness and stability. Mark the position of the anchor bolt on the positioning frame to ensure that the spacing and verticality of the anchor bolt meet the design standards during embedding. Pass the anchor bolt 3 through the anchor bolt positioning frame and embed it in the bottom longitudinal beam, and use chemical anchoring or mechanical anchoring methods to ensure the firm connection between the anchor bolt and the bottom longitudinal beam. In this embodiment, chemical anchoring agent is used to fix the anchor bolt in the reserved hole of the bottom longitudinal beam. The chemical anchoring agent has the advantages of high strength and aging resistance, and can effectively ensure the anchoring effect of the anchor bolt.

[0043] 4. Inserted reinforcement and stirrup setting Set the reserved bottom longitudinal beam reinforcement bars 10 and embedded steel bar stirrups 19 in the bottom longitudinal beam. The length and diameter of the reserved bottom longitudinal beam reinforcement bars are determined according to the design requirements, and their function is to enhance the connection strength between the bottom longitudinal beam and the precast column. The spacing and specifications of the embedded steel bar stirrups are arranged according to the design drawings to improve the overall stability of the bottom longitudinal beam. In this embodiment, the diameter of the reserved bottom longitudinal beam reinforcement bars is 20 mm, the length is 500 mm, and the spacing of the embedded steel bar stirrups is 200 mm, which can effectively restrain the concrete of the bottom longitudinal beam and prevent it from cracking, and then concrete is poured to obtain the bottom longitudinal beam.

[0044] Step 2, manufacture of precast column 1. Binding of main reinforcement bars During the manufacture of the precast column 6, first bind the main reinforcement bars 7 of the precast column. Select steel bars with the same specifications as the main reinforcement bars of the bottom longitudinal beam or meeting the design requirements as the main reinforcement bars of the precast column to ensure the load-bearing capacity of the precast column. During the binding process, strictly control the spacing and arrangement of the main reinforcement bars to ensure the structural uniformity of the precast column. In this embodiment, according to the design requirements, the spacing of the main reinforcement bars of the precast column is 150 mm, and the arrangement is rectangular.

[0045] 2. Welding of connecting steel plates At the bottom of the precast column, weld the main reinforcement bars 7 to the connecting steel plate 11. Before welding, clean the connecting steel plate to remove impurities such as oil stains and rust on the surface to ensure the welding quality. Use appropriate welding processes and welding materials for welding to ensure the strength and toughness of the welded joints. In this embodiment, manual arc welding is used for welding, the welding material is selected as E5015 electrode, and the welding current is controlled between 120 - 150 A to ensure the quality of the welded joints. At the same time, weld the stud 15 to the connecting steel plate 11, and the function of the stud is to enhance the bonding force between the connecting steel plate and the concrete.

[0046] 3. Installation of anchor bolt base plate and stiffeners Set the precast column anchor bolt base plate 5 at the bottom of the precast column 6. The steel bar connecting steel plate 11 and the precast column anchor bolt base plate 5 are connected by full penetration groove welding, and this welding method can ensure the strength and tightness of the connection. The stiffeners 12 and the steel bar connecting steel plate 11 and the precast column anchor bolt base plate 5 are welded by double-sided fillet welds, and the function of the stiffeners is to enhance the stability of the connecting steel plate and the anchor bolt base plate. Open holes 17 at the corresponding positions of the precast column anchor bolt base plate 5, and the size and position of the holes should match the anchor bolts 3 embedded in the bottom longitudinal beam to ensure the accuracy of subsequent installation.

[0047] 4. Setting of corrugated pipes and grouting holes A corrugated pipe 9 is embedded in the center of the prefabricated column 6 and a grouting hole 8 is set. The function of the corrugated pipe 9 is to provide an insertion space for the reserved dowel bar 10 of the bottom longitudinal beam and to form a grouting channel in the subsequent grouting process. The material of the corrugated pipe is a high-strength plastic or metal corrugated pipe with good flexibility and corrosion resistance. The position of the grouting hole 8 should be convenient for the grouting operation, and it should ensure that air can be discharged during the grouting process to ensure the density of the grouting. During the embedding process, ensure that the position of the corrugated pipe 9 corresponds to the reserved dowel bar 10 of the bottom longitudinal beam one by one to ensure the accurate connection between the prefabricated column and the bottom longitudinal beam.

[0048] Step 3: Connect the prefabricated column with the bottom longitudinal beam and cast the column foot 1. Clean the contact surface Clean the contact surface between the prefabricated column anchor bolt base plate 5 and the bottom longitudinal beam anchor bolt base plate 4, remove impurities such as oil, dust and oxide layer on the surface, and ensure that the contact surface is flat and clean. Sandpaper polishing, high-pressure water gun washing, etc. can be used for cleaning, and wipe it with a dry cloth after cleaning to ensure good fit of the contact surface.

[0049] 2. Positioning and connection Insert the embedded anchor 3 into the anchor hole in the prefabricated column anchor base plate 5, and insert the reserved dowel bar 10 of the bottom longitudinal beam into the embedded corrugated pipe 9 in the prefabricated column 6. Set the anchor pad 16 and double nut 13 on the anchor in turn, tighten the double nut 13 with a torque wrench, and control the tightening torque according to the design requirements to ensure the tightness of the connection. After the double nut is tightened, the anchor pad 16 and the prefabricated column anchor base plate 5 are welded around, and a continuous weld is used to ensure the sealing and strength of the welding. At the same time, the prefabricated column anchor base plate 5 and the bottom longitudinal beam anchor base plate 4 are fully welded to further enhance the stability of the connection.

[0050] 3. Corrugated pipe grouting High-strength grouting material is poured into the corrugated pipe 9 through the grouting hole 8. Before grouting, the corrugated pipe is inspected to ensure that there is no debris blocking inside. High-strength grouting material that meets the design requirements is selected, which has the characteristics of early strength, high strength, and micro expansion, and can effectively fill the gap between the corrugated pipe and the inserted reinforcement to enhance the integrity of the connection. During the grouting process, the grouting pressure and grouting speed are controlled to ensure that the grouting material can fully fill the corrugated pipe. After the grouting is completed, the grouting hole is blocked to prevent the grouting material from overflowing.

[0051] 4. Pouring concrete at the column base Pour the column base 14 with concrete, select a suitable concrete mix ratio to ensure the strength and durability of the concrete. During the pouring process, use the method of layered vibration to ensure the compactness of the concrete. When vibrating, avoid touching the anchor bolts and inserted steel bars with the vibrating rod to prevent affecting the stability of the connection. After pouring, cure the column base concrete, using methods such as covering for moisture retention or watering for curing. The curing time is controlled according to the design and specification requirements to ensure the normal growth of the concrete strength.

[0052] Through the above specific implementation process, the prefabricated column base assembled connection structure and construction method of the underground structure of the present invention can effectively improve the mechanical properties and construction efficiency of the column base of the prefabricated underground structure, and ensure the safety and stability of the underground structure.

[0053] The prefabricated column base assembled connection and construction method for the underground structure proposed by the present invention has the following beneficial effects: The positioning of the prefabricated column is realized by setting an anchor bolt base plate between the bottom longitudinal beam and the prefabricated column, and the connection is carried out through the anchor bolts, which is convenient for the positioning and construction of the prefabricated column. Through the anchor bolts around the column base and the reserved steel reinforcement cage in the middle, the effective transfer of the load of the prefabricated column to the bottom longitudinal beam is ensured.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. An assembled connection structure for prefabricated column bases of underground structures, characterized in that: include: A bottom longitudinal beam (1), wherein a bottom longitudinal beam anchor bolt bottom plate (4) and embedded anchor bolts (3) are pre-embedded at the top of the bottom longitudinal beam (1), and a bottom longitudinal beam reserved dowel bar (10) is pre-embedded at the center of the bottom longitudinal beam (1); A prefabricated column (6), wherein a prefabricated column anchor bolt base plate (5) is provided at the bottom of the prefabricated column (6), and the prefabricated column anchor bolt base plate (5) is connected to the bottom longitudinal beam anchor bolt base plate (4) via embedded anchor bolts (3); the prefabricated column (6) comprises a prefabricated column main reinforcement (7) and a connecting steel plate (11), the prefabricated column main reinforcement (7) and the connecting steel plate (11) are welded, and the connecting steel plate (11) and the prefabricated column anchor bolt base plate (5); the bottom longitudinal beam anchor bolt base plate (4) is provided with a connecting hole at a position corresponding to the bottom longitudinal beam embedded anchor bolt (3); A bellows (9) and a grouting hole (8), wherein the bellows (9) and the grouting hole (8) are pre-buried at the bottom center of the prefabricated column (6), the bottom longitudinal beam reserved dowel bar (10) is inserted into the bellows (9), the bellows (9) and the bottom longitudinal beam reserved dowel bar (10) have a one-to-one correspondence in position, and high-strength grouting material is injected through the grouting hole (8).

2. The connection structure according to claim 1, characterized in that: The connecting steel plate (11) is provided with a stiffening rib (12), and the stiffening rib (12) is connected to the prefabricated column anchor bolt base plate (5) by using a double-sided fillet weld.

3. The connection structure according to claim 1, characterized in that: The bottom longitudinal beam (1) is also pre-embedded with bottom longitudinal beam main reinforcement (18) and an anchor bolt positioning frame (2).

4. The connection structure according to claim 1, characterized in that: The prefabricated column anchor bolt base plate (5) of the prefabricated column (6) is connected to the bottom longitudinal beam anchor bolt base plate (4) via a double nut (13) and an anchor bolt pad (16).

5. The connection structure according to claim 1, characterized in that: The connecting steel plate (11) and the prefabricated column anchor bolt bottom plate (5) are connected by penetration groove welding, and the stiffening rib (12) and the connecting steel plate (11) and the prefabricated column anchor bolt bottom plate (5) are welded by double-sided fillet welds.

6. A method for assembling and connecting the base of a prefabricated column of an underground structure, characterized in that: The following steps are involved: Step 1: firstly, tie the main reinforcement (18) of the bottom longitudinal beam; pre-embed the bottom longitudinal beam anchor bolt bottom plate (4) at the top of the bottom longitudinal beam; at the same time, pre-embed the anchor bolt positioning frame (2) in the bottom longitudinal beam, and pre-embed the anchor bolt (3); and set the bottom longitudinal beam reserved dowel (10) and pre-embed the steel stirrup (19) on the bottom longitudinal beam; Step 2: Casting of the stacked prefabricated column (6) is completed in the factory, wherein the prefabricated column (6) is pre-buried with a corrugated pipe (9), a prefabricated column main reinforcement (7) and a connecting steel plate (11), and a grouting hole (8) is provided on the prefabricated column (6), a prefabricated column anchor base plate (5) is provided at the bottom of the prefabricated column (6), the prefabricated column main reinforcement (7) is welded to the connecting steel plate (11), the connecting steel plate (11) is welded to the prefabricated column anchor base plate (5), a stiffening rib (12) and a stud (15) are welded to the connecting steel plate (11), holes are opened at corresponding positions of the prefabricated column anchor base plate (5), and the positions of the corrugated pipe (9) and the reserved dowel bars (10) of the bottom longitudinal beam correspond one to one; Step 3: clean the contact surface between the anchor base plate (5) of the precast column and the anchor base plate (4) of the bottom longitudinal beam, insert the embedded anchor bolt (3) of the bottom longitudinal beam into the opening of the anchor base plate at the bottom of the precast column, insert the reserved dowel bar (10) of the bottom longitudinal beam into the embedded corrugated pipe (9) of the precast column, install the anchor pad (16) and the double nut (13) in sequence and tighten them, weld the anchor pad (16) and the anchor base plate (5) of the precast column, fully weld the anchor base plate (5) of the precast column and the anchor base plate (4) of the bottom longitudinal beam, pour high-strength grouting material into the corrugated pipe (9) through the grouting hole (8), pour the reserved dowel bar (10) of the bottom longitudinal beam into the precast column (6), and pour the column foot concrete at the same time, so as to isolate the anchor base plate (5) of the precast column and the anchor base plate (4) of the bottom longitudinal beam from the air.

7. The method for assembling and connecting the base of a prefabricated column of an underground structure according to claim 6, characterized in that: In step 1, after the main reinforcement (18) of the bottom longitudinal beam is tied, the specifications, spacing and firmness of the reinforcement need to be checked. Only when they meet the design requirements can the subsequent embedding work be carried out.

8. The method for assembling and connecting the base of a prefabricated column of an underground structure according to claim 6, characterized in that: In step 2, when the main reinforcement of the prefabricated column is welded to the connecting steel plate, the welding current, voltage and welding speed are controlled to ensure the welding quality, and non-destructive testing is performed after the welding is completed.

9. The method for assembling and connecting the base of a prefabricated column of an underground structure according to claim 6, characterized in that: In step three, the sealing of the bellows is checked before grouting to ensure that there is no leakage. During the grouting process, the grouting pressure and amount are controlled to ensure that the bellows is fully grouted.

10. The method for assembling and connecting the base of a prefabricated column of an underground structure according to claim 6, characterized in that: In step three, after the column base concrete is poured, it is cured as required. The curing time meets the design and specification requirements to ensure the increase of concrete strength.

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