Assembled steel plate-mud alkali-activated concrete underground composite structure wall and method

Abstract

The invention discloses an assembled steel plate-mud alkali-activated concrete underground composite structure wall and method, belonging to the technical field of underground structures, comprising a steel caisson group, a steel frame group being mounted on the top of the outer surface of the steel caisson group, and the inner cavity of the steel caisson group being filled with mud alkali-activated concrete; the steel caisson group, the mud alkali-activated concrete and the corrugated staggered parts are arranged to realize the assembly into a required overall structure, and after the overall structure is formed, the chamber of the steel caisson group is filled with mud excavated from an underground foundation pit, and the mud alkali-activated concrete is formed after being stimulated to strength by a tailings slag alkali activator, and the corrugated staggered parts in the chamber can make the connection between the mud alkali-activated concrete and the steel caisson group more closely, and the corrugated shape effectively shares the stress of the filled mud, and local materials are used, which greatly reduces the processing cost of the mud excavated from the foundation pit and the cost of transporting concrete over long distances, and truly realizes a waste-free construction site and green and low-carbon.

Description

Technical Field

[0001] The invention relates to the technical field of underground structures, and in particular to an assembled steel plate-mud alkali-activated concrete underground composite structure wall and a method thereof. Background Art

[0002] The underground continuous wall is constructed by using a trenching machine on the ground to dig a long and narrow deep trench along the peripheral axis of the deep excavation project under the condition of mud wall protection. After the trench is cleared, a steel cage is suspended in the trench, and then underwater concrete is poured using the conduit method to form a unit trench section. The trench sections are constructed at intervals to build a continuous reinforced concrete wall underground.

[0003] It has multiple functions such as anti-seepage, water interception, load-bearing, soil retaining, explosion-proof, etc. It is very suitable for various needs and is widely used in anti-seepage of rivers, lakes, ports, docks, sewage treatment plants, basements of high-rise buildings, underground parking lots, subways, bridge construction and other fields.

[0004] Traditional underground composite structural walls are mostly reinforced concrete structures. However, traditional reinforced concrete structures have inherent limitations in underground projects, such as long construction period, large construction disturbance, high cost of long-distance concrete transportation and high cost of excavation mud treatment. In addition, traditional reinforced concrete underground continuous walls have low ductility and poor deformation capacity due to their high structural stiffness. In addition, the construction of traditional reinforced concrete underground continuous walls often encounters problems such as wall intrusion, weak zones at joints, wall bulging, poor concrete molding quality, insufficient durability and impermeability. The existence of these problems seriously affects the quality and safety of the project. Summary of the invention

[0005] The purpose of the present invention is to solve the inherent limitations of traditional reinforced concrete structures in underground projects, such as long construction period, large construction disturbance, high cost of long-distance concrete transportation and high cost of excavation mud treatment, and to propose an assembled steel plate-mud alkali-activated concrete underground composite structure wall and method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The assembled steel plate-mud alkali activated concrete underground composite structural wall comprises a steel caisson group, a steel frame group is sleeved on the top of the outer surface of the steel caisson group, and the inner cavity of the steel caisson group is filled with mud alkali activated concrete;

[0008] The steel caisson group includes a middle box, both ends of the middle box are clamped with side boxes, one end of the side box is clamped with a corner box, the inner walls of the middle box, the side box and the corner box are all equipped with corrugated staggered pieces, and the corrugated staggered pieces are equipped with reinforcement pieces for reinforcing the cast steel caisson group;

[0009] The corrugated staggered parts include long corrugated steel plates fixed on two inner walls of the middle box, side box and corner box, and short corrugated steel plates are fixed on the other two inner walls of the middle box, side box and corner box, so that the mud alkali activated concrete can be tightly connected with the inner cavity of the steel caisson group after pouring.

[0010] As a further description of the above technical solution:

[0011] The reinforcement comprises a steel sleeve inserted into the vertical section of the long corrugated steel plate, and threaded sleeves are fixed to both side walls of the middle box and the side box. The steel sleeve passes through both ends of the long corrugated steel plate and is threadedly connected to two threaded sleeves respectively.

[0012] As a further description of the above technical solution:

[0013] The outer side and inner side of the middle box and the side box are provided with bolt holes corresponding to the threaded sleeves. The steel sleeve is equipped with a bolt whose end is sunk in the inner bolt hole. One end of the bolt that penetrates into the outer bolt hole is threadedly connected with a threaded head, and the threaded head is sunk in the outer bolt hole.

[0014] As a further description of the above technical solution:

[0015] Internal threads are provided on both sides of the inner wall of the steel casing, and external threads matching the internal threads are provided on the outer wall of the bolt, so that the bolt can be threadedly connected with the steel casing after being inserted into the steel casing.

[0016] As a further description of the above technical solution:

[0017] The cavities formed between the long corrugated steel plates and the short corrugated steel plates and the inner walls of the middle box, the side box and the corner box are filled with fillers, and the long corrugated steel plates and the short corrugated steel plates are staggered.

[0018] As a further description of the above technical solution:

[0019] Insert blocks are fixed on both sides of the middle box and one side of the side box, and sockets compatible with the insert blocks are fixed on both sides of the corner box and the other side of the side box, so that the middle box, side box and corner box can be surrounded together to form a combined structural wall.

[0020] As a further description of the above technical solution:

[0021] The steel enclosure group comprises an L-shaped enclosure sleeved on the side boxes and the corner boxes, and a middle enclosure is sleeved on the middle box.

[0022] As a further description of the above technical solution:

[0023] Both ends of the middle enclosure are fixed with T-shaped plates, and both ends of the L-shaped enclosure are provided with T-shaped grooves adapted to the T-shaped plates, so that the middle enclosure can be connected with the L-shaped enclosure.

[0024] As a further description of the above technical solution:

[0025] The slurry alkali activated concrete is a concrete formed after the slurry is activated by a tailings alkali activator to increase its strength.

[0026] The method of fabricating steel plate-mud alkali activated concrete underground composite structural wall includes the following steps:

[0027] S1. First, the middle box, the side box and the corner box are connected together through plug blocks and sockets to form a whole, and then the steel casing is installed;

[0028] S2. After the whole is formed, the inner cavity of the middle box, the side box and the corner box is filled with mud excavated from the underground foundation pit, and the strength is stimulated by the tailings alkali activator to form mud alkali activated concrete;

[0029] S3, insert bolts into the steel casing and fix them through the threaded head to reinforce the steel enclosure group, then put the L-shaped enclosure group on the steel enclosure group and connect them together through the middle enclosure;

[0030] S4. Finally, the whole structure is sunk by caisson technology. After it sinks to the predetermined elevation, the concrete bottom plate is poured to complete the bottom sealing, thereby constructing a complete and continuous underground composite structure wall.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] By setting up the steel caisson group, mud alkali activated concrete and corrugated staggered parts, the required overall structure is assembled, and after the overall structure is formed, the mud excavated from the underground foundation pit is filled in the chamber of the steel caisson group, and the mud alkali activated concrete is formed after the strength is stimulated by the tailings alkali activator. At the same time, the corrugated staggered parts in the chamber can make the connection between the mud alkali activated concrete and the steel caisson group tighter, effectively improving the structural strength. At the same time, the corrugated shape effectively shares the stress of the filling mud, has strong shear resistance, uses local materials, and greatly reduces the processing cost of the mud excavated from the foundation pit and the cost of transporting concrete over long distances. At the same time, the structural wall also has the advantages of simple process, fast construction, high overall rigidity, good water-stopping and anti-seepage effect, and small construction disturbance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It shows a schematic diagram of a structure provided in a three-dimensional manner according to an embodiment of the present invention;

[0034] Figure 2A schematic diagram of the planar structure of the interior of the side box provided according to an embodiment of the present invention is shown;

[0035] Figure 3 The embodiment of the present invention provides Figure 2 The enlarged view of point A in the middle;

[0036] Figure 4 It shows a schematic structural diagram of a reinforcement member after being cut open according to an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of the structure of a corner box provided according to an embodiment of the present invention is shown;

[0038] Figure 6 The embodiment of the present invention provides Figure 5 The enlarged view of point B in the middle;

[0039] Figure 7 A schematic diagram of structural decomposition according to an embodiment of the present invention is shown;

[0040] Figure 8 A schematic diagram of the structural disassembly of a steel enclosure frame group provided according to an embodiment of the present invention is shown;

[0041] Fig. 9 It shows a schematic diagram of the overall structure provided by an embodiment of the present invention;

[0042] Fig.10 The embodiment of the present invention provides Fig. 9 Enlarged view of point C in the middle.

[0043] Legend:

[0044] 10. Steel caisson group; 11. Middle box; 12. Side box; 13. Corner box; 14. Insert block; 15. Socket;

[0045] 20. Steel enclosure set; 21. L-shaped enclosure; 22. Middle enclosure; 23. T-shaped plate; 24. T-shaped slot;

[0046] 30. Mud alkali activated concrete;

[0047] 40. Corrugated interlaced parts; 41. Long corrugated steel plate; 42. Short corrugated steel plate; 43. Filler;

[0048] 50. Reinforcement member; 51. Steel casing; 52. Threaded sleeve; 53. Bolt hole; 54. Bolt; 55. Threaded head; 56. Internal thread; 57. External thread. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] like Figure 1 - Fig.10 As shown, the present invention provides:

[0051] The assembled steel plate-mud alkali activated concrete underground composite structural wall comprises a steel caisson group 10, a steel frame group 20 is mounted on the top of the outer surface of the steel caisson group 10, and the inner cavity of the steel caisson group 10 is filled with mud alkali activated concrete 30;

[0052] The steel caisson group 10 includes a middle box 11, both ends of the middle box 11 are clamped with side boxes 12, one end of the side box 12 is clamped with a corner box 13, the inner walls of the middle box 11, the side boxes 12 and the corner boxes 13 are equipped with corrugated staggered pieces 40, and the corrugated staggered pieces 40 are equipped with reinforcing pieces 50 for reinforcing the cast steel caisson group 10, both sides of the middle box 11 and one side of the side box 12 are fixed with plug blocks 14, and both sides of the corner box 13 and the other side of the side box 12 are fixed with sockets 15 adapted to the plug blocks 14, so that the middle box 11, the side boxes 12 and the corner boxes 13 can be surrounded together to form a combined structural wall;

[0053] Specifically, the steel caisson group 10 realizes rapid assembly and disassembly through the design of the plug block 14 and the socket 15, which not only significantly shortens the construction period, but also reduces labor costs and improves construction efficiency. At the same time, the modular design makes the construction more flexible and adaptable to the needs of different underground spaces. The modular design is also convenient for transportation and storage, reducing the difficulty and cost of construction.

[0054] like Figure 2 , Figure 3 , Figure 5 and Figure 6 As shown, the corrugated staggered member 40 includes a long corrugated steel plate 41 fixed on two inner side walls of the middle box 11, the side box 12 and the corner box 13, and short corrugated steel plates 42 are fixed on the other two inner side walls of the middle box 11, the side box 12 and the corner box 13, so that the mud alkali activated concrete 30 can be closely connected with the inner cavity of the steel caisson group 10 after pouring;

[0055] The cavities formed between the long corrugated steel plates 41 and the short corrugated steel plates 42 and the inner walls of the middle box 11, the side box 12 and the corner box 13 are filled with fillers 43, and the long corrugated steel plates 41 and the short corrugated steel plates 42 are staggered;

[0056] Specifically, the staggered arrangement of the long corrugated steel plate 41 and the short corrugated steel plate 42 increases the contact area between the steel plate and the concrete, thereby improving the bonding force between the concrete and the steel plate, which helps to form an overall force system and enhance the bearing capacity of the structural wall. At the same time, the filler 43 is filled in the cavity between the corrugated steel plate and the inner wall of the steel caisson group 10, thereby enhancing the stability of the structure.

[0057] like Figure 1 , Figure 2 and Figure 3 As shown, the mud alkali activated concrete 30 is a concrete formed after the mud is activated by the tailings alkali activator to increase its strength;

[0058] Specifically, the use of mud alkali-activated concrete 30 realizes the reuse of resources and reduces pollution to the environment, which helps to promote sustainable development. Moreover, since mud alkali-activated concrete 30 utilizes mud at the construction site and tailings alkali activator as raw materials, the material cost is reduced, which helps to reduce the construction cost of the entire project and improve economic benefits.

[0059] like Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the reinforcement 50 includes a steel sleeve 51 inserted into the vertical section of the long corrugated steel plate 41, and threaded sleeves 52 are fixed to both side walls of the middle box 11 and the side box 12. The steel sleeve 51 passes through the long corrugated steel plate 41 and is threadedly connected to the two threaded sleeves 52 at both ends;

[0060] The outer and inner sides of the middle box 11 and the side box 12 are provided with bolt holes 53 corresponding to the threaded sleeves 52. A bolt 54 with an end sunk into the inner bolt hole 53 is installed in the steel casing 51. One end of the bolt 54 inserted into the outer bolt hole 53 is threadedly connected with a thread head 55, and the thread head 55 is sunk into the outer bolt hole 53. Internal threads 56 are provided on both sides of the inner wall of the steel casing 51. External threads 57 matching the internal threads 56 are provided on the outer wall of the bolt 54, so that the bolt 54 can be threadedly connected with the steel casing 51 after being inserted into the steel casing 51.

[0061] Specifically, the structural wall is further reinforced by using the combination of the steel casing 51, the threaded sleeve 52, the bolt 54 and the threaded head 55, which significantly improves the bearing capacity of the structural wall, enabling it to withstand a greater load. The use of the reinforcement 50 also enhances the seismic performance of the structural wall and can disperse stress.

[0062] At the same time, the head of the bolt 54 and the threaded head 55 are sunk into the inner and outer bolt holes 53 and are flush with the inner wall of the steel caisson group 10, so no additional resistance will be brought when the entire structure is sunk.

[0063] like Figure 1 , Figure 7 , Figure 8 and Fig. 9 As shown, the steel frame group 20 includes an L-shaped frame 21 sleeved on the side box 12 and the corner box 13, and a middle frame 22 sleeved on the middle box 11. T-shaped plates 23 are fixed at both ends of the middle frame 22, and T-shaped grooves 24 adapted to the T-shaped plates 23 are opened at both ends of the L-shaped frame 21, so that the middle frame 22 can be connected to the L-shaped frame 21.

[0064] Specifically, the steel frame group 20 is composed of an L-shaped frame 21 and a middle frame 22, and a complete frame structure is formed by connecting a T-shaped plate 23 and a T-shaped groove 24. This frame structure improves the lateral force resistance of the structural wall. When subjected to horizontal loads, the steel frame group 20 can disperse stress and enhance the stability of the structure.

[0065] The method of fabricating steel plate-mud alkali activated concrete underground composite structural wall includes the following steps:

[0066] S1, firstly connect the middle box 11, the side box 12 and the corner box 13 together through the plug block 14 and the socket 15 to form a whole, and install the steel casing 51;

[0067] S2, after the whole is formed, the inner cavity of the middle box 11, the side box 12 and the corner box 13 is filled with mud excavated from the underground foundation pit, and the strength is stimulated by the tailings alkali activator to form mud alkali activated concrete 30;

[0068] S3, insert the bolt 54 into the steel casing 51 and fix it through the threaded head 55 to reinforce the steel enclosure group 20, then put the L-shaped enclosure 21 on the steel enclosure group 20 and connect them together through the middle enclosure 22;

[0069] S4. Finally, the whole structure is sunk by caisson technology. After it sinks to the predetermined elevation, the concrete bottom plate is poured to complete the bottom sealing, thereby constructing a complete and continuous underground composite structure wall.

[0070] Specifically, the prefabricated steel plate-mud alkali-activated concrete underground composite structure wall, due to its special structural form, is mainly composed of steel plates, concrete walls and connecting components. It can be continuously constructed and fully formed. Its quality is reliable, and it has good compressive resistance and good impermeability. Therefore, it can be used as a foundation pit support structure, which greatly saves construction time and investment, while reducing risks and adverse effects on society, with obvious comprehensive benefits.

[0071] In addition, the structure tightly connects multiple steel caissons into an integral structure, thereby constructing a fully enclosed space in the wall. This change enables the entire structure to act as a unified and coordinated force-bearing unit, significantly enhancing the stability and bearing capacity of the overall structure, and realizing a form that traditional reinforced concrete structures cannot achieve. The structure also has the advantages of good construction quality, fast construction, high overall rigidity, good water-stopping and anti-seepage effects, high assembly rate, resource conservation, and green environmental protection. The structure makes up for the defects of traditional structures very well. At the same time, the new structure is combined with the construction technology of traditional caissons. While giving full play to the advantages of the new structure, the advantages of the caisson technology such as small construction disturbance, large burial depth, and less excavation are utilized.

[0072] It can be used as a temporary support structure or as a permanent underground continuous wall structure. As the highlight of the caisson technology, the advantage of the combination of permanent and temporary is that the main structure constructed on the ground is directly used for the soil sinking in the subsequent excavation process, so that the structure itself has the function of foundation pit enclosure. This design cleverly replaces the temporary support structure required for the traditional foundation pit with a permanent structure, such as underground continuous walls, internal supports and steel columns, thereby greatly reducing the workload of setting up and dismantling temporary facilities, not only saving building materials and resources, but also significantly shortening the overall construction period of the project. In addition, the combination of permanent and temporary also enhances the functionality and practicality of the project, so that the project can be put into use more quickly after completion to meet diverse functional requirements. This structure is sunk by the caisson technology, taking advantage of its efficient construction, small amount of excavation and the advantages of permanent and temporary combination, combined with the characteristics of short construction time and high efficiency of prefabricated structure, which significantly reduces the burden of on-site work. Thanks to this method, processes such as cumbersome steel bar binding, underground continuous wall support and cast-in-place pile construction are greatly reduced, which greatly improves the construction speed and effectively saves precious time costs. This constitutes an important economic advantage in the application of this technology.

[0073] In underground structures, reinforced concrete walls do not require high stiffness due to their three-dimensional stress characteristics, but their actual stiffness far exceeds the standard, resulting in unnecessary waste of resources. In contrast, the steel plate-concrete composite structure wall uses the stiffness of the steel plate itself to meet the needs of underground continuous walls, which relaxes the choice of filling materials inside the caisson and can turn to economical, low-carbon, and environmentally friendly alternatives. To this end, we actively explore and utilize various types of industrial waste, including silt, mud, industrial waste, and soil generated by excavation, in order to achieve efficient recycling of these resources and thus reduce production costs.

[0074] In addition to filling ordinary concrete in the steel plate, the steel plate-concrete underground composite structural wall can also be filled with foam concrete and solid waste concrete, etc., and can even be filled with mud from foundation pit excavation. In actual construction, this structural wall uses mud alkali-activated concrete as the filling material.

[0075] Using an alkali-activated cementitious material system to treat waste mud can consume a large amount of construction waste, save production costs, and combine two "green materials". The alkaline slurry of recycled aggregate plays a positive role in the slag base, and the strength of the combination of the two is higher than that of ordinary recycled concrete, so there is a possibility of achieving better performance by combining the two.

[0076] Mud alkali activated concrete greatly reduces the cost of long-distance concrete transportation and the cost of excavated mud treatment, truly achieving a waste-free construction site and being green and low-carbon.

[0077] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An assembled steel plate-mud alkali-activated concrete underground composite structural wall, comprising a steel caisson group (10), wherein a steel frame group (20) is sleeved on the top of the outer surface of the steel caisson group (10), characterized in that: The inner cavity of the steel caisson group (10) is filled with mud alkali activated concrete (30); The steel caisson assembly (10) comprises a middle box (11), both ends of the middle box (11) are clamped with side boxes (12), one end of the side box (12) is clamped with a corner box (13), the inner walls of the middle box (11), the side box (12) and the corner box (13) are all equipped with corrugated staggered pieces (40), and the corrugated staggered pieces (40) are equipped with reinforcing pieces (50) for reinforcing the cast steel caisson assembly (10); The corrugated staggered member (40) comprises a long corrugated steel plate (41) fixed on two inner side walls of the middle box (11), the side box (12) and the corner box (13), and short corrugated steel plates (42) are fixed on the other two inner side walls of the middle box (11), the side box (12) and the corner box (13), so that the mud alkali activated concrete (30) can be tightly connected with the inner cavity of the steel caisson group (10) after pouring.

2. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 1 is characterized in that: The reinforcement member (50) comprises a steel casing (51) inserted into the vertical section of the long corrugated steel plate (41), and threaded sleeves (52) are fixed to both side walls of the middle box (11) and the side box (12), and the steel casing (51) passes through both ends of the long corrugated steel plate (41) and is respectively threadedly connected to the two threaded sleeves (52).

3. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 2 is characterized in that: The outer sides and inner sides of the middle box (11) and the side box (12) are both provided with bolt holes (53) corresponding to the threaded sleeves (52); a bolt (54) with an end sunk into the inner bolt hole (53) is installed in the steel sleeve (51); one end of the bolt (54) inserted into the outer bolt hole (53) is threadedly connected with a thread head (55); the thread head (55) is sunk into the outer bolt hole (53).

4. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 3 is characterized in that: Internal threads (56) are provided on both sides of the inner wall of the steel casing (51), and external threads (57) matching the internal threads (56) are provided on the outer wall of the bolt (54), so that the bolt (54) can be threadedly connected to the steel casing (51) after being inserted into the steel casing (51).

5. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 1 is characterized in that: The cavities formed between the long corrugated steel plates (41) and the short corrugated steel plates (42) and the inner walls of the middle box (11), the side box (12) and the corner box (13) are filled with fillers (43), and the long corrugated steel plates (41) and the short corrugated steel plates (42) are staggered.

6. The assembled steel plate-mud alkali activated concrete underground composite structural wall according to claim 5 is characterized in that: Insert blocks (14) are fixed to both sides of the middle box (11) and one side of the side box (12), and sockets (15) compatible with the insert blocks (14) are fixed to both sides of the corner box (13) and the other side of the side box (12), so that the middle box (11), the side box (12) and the corner box (13) can be enclosed together to form a combined structural wall.

7. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 6 is characterized in that: The steel enclosure set (20) comprises an L-shaped enclosure (21) sleeved on the side box (12) and the corner box (13), and a middle enclosure (22) sleeved on the middle box (11).

8. The assembled steel plate-mud alkali activated concrete underground composite structure wall according to claim 7 is characterized in that: T-shaped plates (23) are fixed to both ends of the middle surrounding frame (22), and T-shaped grooves (24) matching the T-shaped plates (23) are provided at both ends of the L-shaped surrounding frame (21), so that the middle surrounding frame (22) can be connected to the L-shaped surrounding frame (21).

9. The fabricated steel plate-mud alkali activated concrete underground composite structural wall according to claim 1, characterized in that: The slurry alkali activated concrete (30) is a concrete formed after the slurry is activated by a tailings alkali activator to increase its strength.

10. The method for the fabricated steel plate-mud alkali activated concrete underground composite structure wall according to any one of claims 1 to 9, characterized in that: The steps include: S1, firstly, the middle box (11), the side box (12) and the corner box (13) are connected together through the plug block (14) and the socket (15) to form a whole, and then the steel casing (51) is installed; S2, after the whole is formed, the inner cavity of the middle box (11), the side box (12) and the corner box (13) is filled with mud excavated from the underground foundation pit, and the strength is stimulated by the tailings alkali activator to form mud alkali activated concrete (30); S3, insert the bolt (54) into the steel casing (51) and fix it through the threaded head (55) to reinforce the steel enclosure group (20), then put the L-shaped enclosure group (21) on the steel enclosure group (20) and connect them together through the middle enclosure group (22); S4. Finally, the whole structure is sunk by caisson technology. After it sinks to the predetermined elevation, the concrete bottom plate is poured to complete the bottom sealing, thereby constructing a complete and continuous underground composite structure wall.

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