Press-in type open caisson without external pile foundation and construction method of press-in type open caisson

Abstract

The invention relates to the technical field of building construction, and particularly discloses a press-in type open caisson without an external pile foundation and a construction method thereof.The press-in type open caisson comprises an anchor foundation, a connecting system, a well wall, an open caisson structure and a retaining wall, and the anchor foundation, the connecting system, the well wall and the open caisson structure are all located within the well wall projection range of the open caisson; the well wall is located in the retaining wall, a plurality of connecting columns are arranged on the retaining wall, the inner side of each connecting column is connected with a connecting system, the inner side of each connecting system is connected with an anchor foundation, and bottom sealing concrete is arranged at the lower end of the open caisson structure; the anchor foundation comprises two end sealing plates, two outer sealing plates and two inner rib plates, the two end sealing plates and the two inner rib plates are arranged in parallel, and the two inner rib plates are located between the two end sealing plates. According to the method, the open caisson process can better adapt to complex surrounding environment conditions of a central urban area, the application range of the press-in type open caisson process is widened, and the engineering land area and land acquisition cost are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and particularly relates to a pressed-in open caisson without external pile foundations and a construction method thereof. Background Art

[0002] Given that the open caisson construction method can achieve excavation without dewatering, in the case of relatively deep burial depth, high risk of confined water, and high requirements for surrounding environmental protection, more and more underground projects adopt the open caisson construction method. The pressed-in open caisson is an advanced version of the open caisson technology. By adopting an auxiliary sinking system, the sinking accuracy of the open caisson can be accurately controlled, greatly expanding the application field of the open caisson construction method.

[0003] Conventional pressed-in open caissons generally set auxiliary sinking systems on both sides, and the reaction force required for their sinking force is provided by driving pile foundations. At the same time, the pile foundations can provide uplift resistance for the subsequent permanent structure. Existing technology pile foundations are all set outside the open caisson. To ensure the need for controlling the sinking attitude of the open caisson, a net distance of 0.8 m - 1 m is generally reserved between the pile foundation and the open caisson. The pile foundation generally adopts the form of bored cast-in-place piles or under-reamed piles.

[0004] Currently, the following areas for improvement still exist in the existing technology: (1) The external pile foundation, as a permanent structure, greatly widens the cross-sectional width of the entire open caisson structure, significantly increasing the land use area of the underground project. The total width generally widens by 3 m - 4 m, resulting in land waste and an increase in project investment. Taking the subway station constructed by the open caisson method as an example, the land acquisition cost will increase by 15% - 20% correspondingly after the width increases.

[0005] (2) When implementing underground projects, if they occupy municipal roads, generally following the principle of "one for one replacement", the original traffic is diverted. Since the open caisson adopts an external pile foundation, the open caisson construction period occupies a larger site, resulting in more lanes being occupied and having a greater impact on municipal traffic.

[0006] (3) Considering that the pile foundation of the open caisson is a permanent structure, all pipelines within this range need to be relocated during the construction period, whether it is the open caisson or the pile foundation. Since the open caisson adopts an external pile foundation, the amount of pipeline relocation is larger. Moreover, there is a joint between the pile foundation and the open caisson, so there is no space for horizontal pipelines to pass through.

[0007] (4) After the structure is formed, a top ring beam needs to be set at the pile head position to connect the external pile foundation and the open caisson structure. This structure is located above the top plate and below the ground, and its elevation is close to the elevation of conventional pipelines, occupying the municipal pipeline laying space. And it is set for the entire length of the station or underground facility, with a large range, which is not conducive to the subsequent development and utilization of underground space.

[0008] Therefore, in the case of limited engineering land, high groundwater level, and strict engineering quality requirements, by innovating the jacked caisson technology and optimizing the external pile foundation, it can be completed safely, economically, and efficiently, which is of great significance to the field of jacked caissons. Summary of the Invention

[0009] To solve the above problems existing in the prior art, the present invention provides a jacked caisson without an external pile foundation and its construction method, which can make the caisson technology more adaptable to the complex surrounding environmental conditions in the central urban area, broaden the application scope of the jacked caisson technology, and save the engineering land area and land acquisition costs.

[0010] The object of the present invention can be achieved by the following technical solutions: A jacked caisson without an external pile foundation includes an anchor base, a connection system, a well wall, a caisson structure, and a retaining wall. The anchor base, connection system, well wall, and caisson structure are all within the projection range of the well wall of the caisson. The well wall is located inside the retaining wall. A plurality of connecting columns are provided on the retaining wall. An inner side of each connecting column is connected to a connection system, an inner side of each connection system is connected to an anchor base, and a bottom sealing concrete is provided at the lower end of the caisson structure. The anchor base includes two end sealing plates, two outer sealing plates, and two inner rib plates. The two end sealing plates and the two inner rib plates are all arranged in parallel. The two inner rib plates are located between the two end sealing plates. The two outer sealing plates are respectively located at both ends of the two end sealing plates. The two outer sealing plates are perpendicular to the two end sealing plates. Post-cast concrete is provided in the internal space surrounded by the two end sealing plates and the two outer sealing plates, and a plurality of built-in grouting holes are provided on the post-cast concrete.

[0011] Further, the anchor base is made of a steel-concrete composite material. A plurality of slurry outlet holes are provided on the post-cast concrete. A grouting pipe is provided in each of the built-in grouting holes, and the plurality of slurry outlet holes are all communicated with the grouting pipes.

[0012] Further, a plurality of tooth blocks are provided on an outer side of each anchor base, and the plurality of tooth blocks are distributed in a plum blossom shape around the outer edge of the anchor base.

[0013] Further, an anchor head plate is fixedly provided at the top of each anchor base. A top sealing plate is fixedly provided at an upper end of each anchor head plate. A plurality of reserved grouting holes are provided on each top sealing plate. A reserved cable hole is provided at a central position of each anchor head plate and the corresponding top sealing plate. A coping plate is fixedly provided on both sides of each anchor base through shear-resistant rib plates, and each coping plate is perpendicular to the top sealing plate.

[0014] Furthermore, a bottom plate is provided at the upper end of the bottom-sealing concrete, and the bottom plate and the anchor foundation are fixedly connected by stud bolts.

[0015] Furthermore, a connecting arm is fixedly provided at the lower end of each connecting column through a side lower anchor plate, and each anchor foundation and the corresponding connecting arm are fixedly connected through an anchor backing plate.

[0016] Furthermore, each connecting arm and the corresponding anchor foundation are fixedly connected through a tension anchor cable.

[0017] Furthermore, a pull rod is provided at the upper end of each connecting arm, and each pull rod is fixedly connected to the connecting column through a side upper anchor plate, and the plurality of pull rods are all in an I-shaped structure.

[0018] Furthermore, a plurality of truss rods are arranged between each pull rod and the connecting arm, and the plurality of truss rods are all in an M-shaped structure.

[0019] A construction method for a pressed-in open caisson without an external pile foundation includes the steps: S1: Construct the anchor foundation; S2: Pour the first-stage open caisson blade foot, shaft wall and open caisson structure, install a connection system and a sinking assistance device inside the shaft wall, and sink the first-stage open caisson structure; S3: Pour the second-stage open caisson structure, fill the open caisson with water, and use underwater non-drainage excavation for subsequent excavation. Install a connection system and a sinking assistance device inside the shaft wall, and sink the open caisson structure; S4: Pour the third-stage open caisson structure, connecting columns and retaining walls, install a connection system and a sinking assistance device inside the connecting columns, fill the open caisson with water, continue to use underwater non-drainage excavation, and sink the open caisson structure; S5: Pour underwater the bottom-sealing plain concrete, pump out and drain all the water inside the open caisson, scour the exposed anchor foundation, and weld stud bolts within the range of the bottom plate; S6: Pour the bottom plate. After reaching the design strength, cut off the part of the anchor foundation above the bottom plate, pour the internal structure of the open caisson layer by layer from bottom to top. After the top plate is completed, remove the connecting columns and the connection system, and backfill with soil to complete the open caisson structure.

[0020] The beneficial effects of the present invention are: (1) By setting the anchor base, connection system, caisson structure and retaining wall, the achievable technical effects are that the anchor base, connection system, well wall and caisson structure are all within the projection range of the well wall of the caisson. The press-in caisson can solve the problems of excessive width of conventional press-in caissons, large amount of pipeline relocations, and difficult traffic diversion, making the caisson technology more adaptable to the complex surrounding environmental conditions in the central urban area, broadening the application scope of the press-in caisson technology, saving the project land area and land acquisition costs, and economically, reasonably, safely and efficiently completing the layout of the press-in caisson structure without the external pile foundation set in conventional press-in caissons.

[0021] (2) By setting the anchor base and connection system, the achievable technical effects are to realize the auxiliary sinking function of the press-in caisson, and the well wall is located inside the retaining wall. There are multiple connecting columns on the retaining wall, and each inner side of each connecting column is connected with a connection system, and each inner side of each connection system is connected with an anchor base. The lower end of the caisson structure is provided with underwater concrete sealing, and the connection system provides force transmission for the sinking of the caisson. The anchor base is constructed by the static pressure process, and the section demarcation position is connected by welding. The welding uses groove penetration welding to achieve equal-strength welding at the interface.

[0022] (3) By setting the grout outlet holes and grouting pipes, the achievable technical effects are that the anchor base includes two end sealing plates, two outer sealing plates and two inner rib plates. The two end sealing plates and the two inner rib plates are all arranged in parallel. The two inner rib plates are located between the two end sealing plates. The two outer sealing plates are respectively located at both ends of the two end sealing plates. The two outer sealing plates are perpendicular to the two end sealing plates. Post-cast concrete is arranged in the internal space surrounded by the two end sealing plates and the two outer sealing plates. The post-cast concrete is used to increase the structural stiffness. Multiple built-in grouting holes are opened on the post-cast concrete. The anchor base is made of steel-concrete composite material. Multiple grout outlet holes are opened on the post-cast concrete. Each built-in grouting hole is provided with a grouting pipe, and multiple grout outlet holes are all communicated with the grouting pipe. Grouting is carried out in the grouting pipe to increase the adhesion and friction resistance between the outside of the anchor base and the soil.

[0023] (4) By setting the anchor base, the achievable technical effects are that during the caisson construction stage, the anchor base provides uplift resistance for the sinking of the caisson; during the caisson use stage, the anchor base provides buoyancy resistance for the anti-floating of the caisson during future use, and also provides a relatively stable foundation for the caisson structure to control the uneven settlement at the bottom of the caisson. The anchor base during the caisson construction period is a full-length member. During the caisson use stage, the anchor base is truncated at the bottom plate. The anti-floating load-bearing members during the permanent use stage are located at the bottom plate and below, so that there are no members occupying the underground space above the top plate, which is beneficial to the subsequent development and utilization of the underground space. Description of the Drawings

[0024] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the drawings.

[0025] Figure 1 Overall plan view of the present invention; Figure 2 Overall cross-sectional view of the present invention; Figure 3 Cross-sectional view of the anchor base structure of the present invention; Figure 4 Arrangement plan of the slurry outlet holes reserved for the anchor base of the present invention; Figure 5 Arrangement plan of the outer toothed blocks of the anchor base of the present invention; Figure 6 Top plan view of the anchor base of the present invention; Figure 7 Cross-sectional view during the use stage of the present invention; Figure 8 Schematic diagram of the anchor base at the bottom plate position of the present invention; Figure 9 First plan view of the connection system of the present invention; Figure 10 Second plan view of the connection system of the present invention; Figure 11 Cross-sectional view of the connection system of the present invention; Figure 12 A - A cross-sectional view of the connection system of the present invention; Figure 13 B - B cross-sectional view of the connection system of the present invention; Figure 14 C - C cross-sectional view of the connection system of the present invention; Figure 15 Construction procedure diagram of S1 of the present invention; Figure 16 Construction procedure diagram of S2 of the present invention; Figure 17 Construction procedure diagram of S3 of the present invention; Figure 18 Construction procedure diagram of S4 of the present invention; Figure 19 Construction procedure diagram of S5 of the present invention; Figure 20 Construction procedure diagram of S6 of the present invention; Explanation of reference numerals: In the figure: 1. Connection system; 2. Retaining wall; 3. Truss rod; 4. Connection column; 5. Well wall; 6. Open caisson structure; 7. Bottom sealing concrete; 8. Anchor base; 9. End sealing plate; 10. Outer sealing plate; 11. Inner rib plate; 12. Post-cast concrete; 13. Built-in grouting hole; 14. Grout outlet hole; 15. Tooth block; 16. Shear-resistant rib plate; 17. Eaves plate; 18. Top sealing plate; 19. Reserved hole for grouting hole; 20. Reserved hole for anchor cable; 21. Anchor head plate; 22. Bottom plate; 23. Stud; 24. Tensioned anchor cable; 25. Tie rod; 26. Anchor backing plate; 27. Lower side anchor plate; 28. Connection arm; 29. Upper side anchor plate. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application; obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0027] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0029] Refer to Figures 1 to 14 , a press-in open caisson without an external pile foundation disclosed in the present invention, includes an anchor base 8, a connection system 1, a well wall 5, an open caisson structure 6, and a retaining wall 2. The anchor base 8, the connection system 1, the well wall 5, and the open caisson structure 6 are all within the projection range of the well wall 5 of the open caisson.

[0030] The well wall 5 is located inside the retaining wall 2. A plurality of connecting columns 4 are provided on the retaining wall 2. An inner side of each connecting column 4 is connected to a connecting system 1, and an inner side of each connecting system 1 is connected to an anchor base 8. A bottom-sealing concrete 7 is provided at the lower end of the open caisson structure 6. The connecting system 1 provides force transmission for the sinking of the open caisson. The anchor base 8 is constructed by a static pressure process. The section demarcation position is connected by welding, and the welding adopts groove penetration welding to achieve equal-strength welding at the interface.

[0031] The anchor base 8 includes two end sealing plates 9, two outer sealing plates 10 and two inner rib plates 11. The two end sealing plates 9 and the two inner rib plates 11 are arranged in parallel. The two inner rib plates 11 are located between the two end sealing plates 9. The two outer sealing plates 10 are respectively located at both ends of the two end sealing plates 9. The two outer sealing plates 10 are perpendicular to the two end sealing plates 9. Post-cast concrete 12 is provided in the internal space surrounded by the two end sealing plates 9 and the two outer sealing plates 10. The post-cast concrete 12 is used to increase the structural stiffness, and a plurality of built-in grouting holes 13 are opened on the post-cast concrete 12.

[0032] The anchor base 8 is made of a steel-concrete composite material. A plurality of slurry outlet holes 14 are opened on the post-cast concrete 12. A grouting pipe is arranged in each built-in grouting hole 13. The plurality of slurry outlet holes 14 are all communicated with the grouting pipe, and grouting is carried out in the grouting pipe to increase the adhesion and frictional resistance between the outside of the anchor base 8 and the soil.

[0033] A plurality of tooth blocks 15 are provided on the outer side of each anchor base 8. The plurality of tooth blocks 15 are distributed in a plum blossom shape around the outer edge of the anchor base 8. The tooth blocks 15 are 50 mm wide, 35 mm deep, spaced 100 mm apart, and the upper and lower rows of tooth blocks 15 are arranged staggeredly.

[0034] A top anchor plate 21 is fixedly provided at the top of each anchor base 8. A top sealing plate 18 is fixedly provided at the upper end of each top anchor plate 21. A plurality of grouting hole reserved holes 19 are opened on each top sealing plate 18. A cable anchor reserved hole 20 is opened at the central position of each top anchor plate 21 and the corresponding top sealing plate 18. A coping plate 17 is fixedly provided on both sides of each anchor base 8 through a shear-resistant rib plate 16. The shear-resistant rib plate 16 is connected by welding. The shear-resistant rib plate 16 is used to strengthen the shear bearing capacity between the top anchor plate 21 and the anchor base 8. Each coping plate 17 is perpendicular to the top sealing plate 18. A reserved hole for the auxiliary sinking tension cable 24 is reserved on the top sealing plate 18, and the size of the reserved hole is 150 mm × 150 mm.

[0035] A bottom plate 22 is provided at the upper end of the bottom-sealing concrete 7. The bottom plate 22 and the anchor base 8 are fixedly connected by stud bolts 23.

[0036] At the lower end of each connecting column 4, a connecting arm 28 is fixedly arranged through a side lower anchor plate 27, and each anchor base 8 and the corresponding connecting arm 28 are fixedly connected through an anchor backing plate 26. Each connecting arm 28 and the corresponding anchor base 8 are fixedly connected through a tension anchor cable 24.

[0037] At the upper end of each connecting arm 28, a tie rod 25 is arranged. Each tie rod 25 is fixedly connected to the connecting column 4 through a side upper anchor plate 29, and multiple tie rods 25 are all in an I-shaped structure. Between each tie rod 25 and the connecting arm 28, multiple truss rods 3 are arranged. The multiple truss rods 3 are in an M-shaped structure, and the connecting arm 28 is a cantilever structure.

[0038] The layout position of the anchor base 8 is determined according to the inner edge line position of the caisson cutting edge, the construction deviation values of the caisson and the anchor base 8, and the requirements of the underwater excavation space. According to the existing dredging and mud cleaning process, generally the gap is 0.7m - 0.9m. On the premise of meeting the earth excavation process, the smaller the spacing, the better.

[0039] During the construction stage of the caisson, the anchor base 8 provides uplift resistance for the caisson sinking; during the service stage of the caisson, the anchor base 8 provides buoyancy resistance for the anti-floating during the future use of the caisson, and at the same time provides a relatively stable foundation for the caisson structure 6, controlling the uneven settlement at the bottom of the caisson.

[0040] The anchor base 8 during the caisson construction period is a full-length member. During the service stage of the caisson, the anchor base 8 is truncated at the bottom plate 22. The anti-floating force-bearing members in the permanent use stage are located at and below the bottom plate 22, so that there are no members occupying the underground space above the top plate, which is beneficial to the subsequent development and utilization of the underground space.

[0041] The pressed caisson can solve problems such as the too large width of the conventional pressed caisson, the large amount of pipeline relocation, and the difficult traffic diversion, making the caisson process more adaptable to the complex surrounding environmental conditions in the central urban area, broadening the application range of the pressed caisson process, saving the project land area and land acquisition costs, and economically, reasonably, safely and efficiently completing the layout of the pressed caisson structure 6.

[0042] Refer to Figures 15 to 20 , a construction method of a pressed caisson without an external pile foundation, including the steps: S1: Construct the anchor base 8. The anchor base 8 is a support in the factory, transported to the site, and constructed by the static pressure method and driven in. The anchor base 8 can be fabricated in sections and welded on site during driving. S2: Pour the first section of the caisson cutting edge, the well wall 5 and the caisson structure 6. Install the connection system 1 and the sinking assistance device inside the well wall 5, and sink the first section of the caisson structure 6. S3: Pour the second section of the caisson structure 6. Fill the caisson with water, and the subsequent excavation adopts underwater non-draining excavation. Install the connection system 1 and the sinking assistance device inside the well wall 5, and sink the caisson structure 6. S4: Pour the third-section open caisson structure 6, connecting columns 4 and retaining walls 2. Install the connection system 1 and the sinking assistance device inside the connecting columns 4. Fill the open caisson with water and continue with underwater non-drainage excavation to sink the open caisson structure 6. S5: Pour underwater the blinding concrete for the bottom seal, pump out all the water inside the open caisson. After scouring the exposed anchor bases 8, weld stud bolts 23 within the range of the bottom slab 22. S6: Pour the bottom slab 22. After it reaches the design strength, cut off the part of the anchor base 8 above the bottom slab 22. Pour the internal structure of the open caisson layer by layer from bottom to top. After the top slab is completed, remove the connecting columns 4 and the connection system 1, and then backfill with soil to complete the open caisson structure 6.

[0043] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to form equivalent embodiments with equivalent changes, provided that they do not depart from the technical solution of the present invention. Any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A press-in caisson without external pile foundation, characterized in that: It includes an anchor foundation, a connection system, a well wall, a caisson structure and a retaining wall, wherein the anchor foundation, the connection system, the well wall and the caisson structure are all located within the projection range of the well wall of the caisson; The well wall is located inside the retaining wall, a plurality of connecting columns are arranged on the retaining wall, the inner side of each connecting column is connected to a connecting system, the inner side of each connecting system is connected to an anchor base, and the lower end of the caisson structure is provided with bottom sealing concrete; The anchor base includes two end sealing plates, two outer sealing plates and two inner rib plates. The two end sealing plates and the two inner rib plates are arranged in parallel. The two inner rib plates are located between the two end sealing plates. The two outer sealing plates are respectively located at the two ends of the two end sealing plates. The two outer sealing plates are perpendicular to the two end sealing plates. Post-cast concrete is arranged in the internal space surrounded by the two end sealing plates and the two outer sealing plates. A plurality of built-in grouting holes are opened on the post-cast concrete.

2. A press-in caisson without external pile foundation according to claim 1, characterized in that: The anchor base is made of a steel-concrete composite material. A plurality of grouting holes are provided on the post-cast concrete. A grouting pipe is provided in each of the built-in grouting holes, and the plurality of grouting holes are all connected to the grouting pipe.

3. A press-in caisson without external pile foundation according to claim 1, characterized in that: A plurality of tooth blocks are arranged on the outer side of each anchor base, and the plurality of tooth blocks are distributed in a plum blossom shape along the outer edge of the anchor base.

4. A press-in caisson without external pile foundation according to claim 1, characterized in that: An anchor head plate is fixedly provided on the top of each anchor base, a top sealing plate is fixedly provided on the upper end of each anchor head plate, a plurality of reserved holes for grouting holes are provided on each top sealing plate, an anchor cable reserved hole is provided at the center position of each anchor head plate and the corresponding top sealing plate, a brim plate is fixedly provided on both sides of each anchor base through shear ribs, and each brim plate is perpendicular to the top sealing plate.

5. The press-in caisson without external pile foundation according to claim 1, characterized in that: A bottom plate is arranged at the upper end of the bottom sealing concrete, and the bottom plate is fixedly connected to the anchor base by bolts.

6. A press-in caisson without external pile foundation according to claim 1, characterized in that: The lower end of each connecting column is fixedly provided with a connecting arm through a side lower anchor plate, and each anchor base and the corresponding connecting arm are fixedly connected through an anchor pad.

7. A press-in caisson without external pile foundation according to claim 6, characterized in that: Each of the connecting arms and the corresponding anchor base is fixedly connected via a tensioned anchor cable.

8. The press-in caisson without external pile foundation according to claim 6, characterized in that: A pull rod is arranged at the upper end of each connecting arm, and each pull rod is fixedly connected to the connecting column through an upper side anchor plate, and a plurality of the pull rods are in an I-shaped structure.

9. A press-in caisson without external pile foundation according to claim 8, characterized in that: A plurality of truss rods are arranged between each of the pull rods and the connecting arms, and the plurality of truss rods are in an M-shaped structure.

10. A construction method for a press-in caisson without an external pile foundation, applied to the press-in caisson as claimed in any one of claims 1 to 9, characterized in that: Includes steps: S1: Construction of anchor foundation; S2: Cast the first section of the caisson blade, the well wall and the caisson structure, install the connection system and the sinking aid device on the inner side of the well wall, and sink the first section of the caisson structure; S3: Cast the second section of the caisson structure, fill the caisson with water, and use underwater undrained excavation for subsequent excavation. Install the connection system and sinking aid device on the inner side of the well wall to sink the caisson structure; S4: Cast the third section of the caisson structure, connecting columns and retaining walls, install the connection system and sinking aid device on the inner side of the connecting columns, fill the caisson with water, continue to use underwater undrained excavation, and sink the caisson structure; S5: Pour the bottom sealing plain concrete underwater, drain the water inside the caisson, flush the exposed anchor foundation, and weld bolts on the bottom plate; S6: Cast the bottom plate. After reaching the designed strength, cut off the anchor foundation above the bottom plate, and cast the internal structure of the caisson layer by layer from bottom to top. After the top plate is completed, remove the connecting columns and the connecting system, and backfill with soil to complete the caisson structure.

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