Ultra-long steel sheet pile cofferdam for complex geology in navigable water area and construction method

Abstract

The invention relates to an ultra-long steel sheet pile cofferdam for the complex geology of a navigable water area and a construction method. The construction method comprises the following steps that firstly, a steel pile casing at the top of a pipe pile is used for connecting and installing steel sheet piles and a positioning frame of an enclosing purlin; a steel sheet pile construction positioning frame is constructed by installing enclosing purlins on the positioning frame; secondly, holes are formed in the positions, corresponding to the soil layers, of the steel sheet piles; a steel sheet pile is driven to be anchored with the gravel mixture in the hole; thirdly, inner supports are installed through surrounding purlins and buoyancy tanks, the two ends of the buoyancy tanks are temporarily fixed to the steel sheet piles, and the surrounding purlins are matched to control the installation elevation of the inner supports; fourthly, concrete bottom sealing construction is conducted; the method has the beneficial effects that accurate positioning of the steel sheet pile is achieved by constructing the construction positioning frame; steel casings are connected to form a positioning frame, enclosing purlins are installed and matched with buoyancy tanks to assist in installation of inner supports, elevation is flexibly adjusted through movable blocks and the buoyancy tanks, and stability and flexibility of construction positioning reference are guaranteed; and the long-term stability of the cofferdam is ensured by anchoring the bottoms of the steel sheet piles and

Description

Technical Field

[0001] The invention belongs to the field of bridge engineering, and in particular relates to an ultra-long steel sheet pile cofferdam in navigable waters with complex geology and a construction method thereof. Background Art

[0002] When constructing infrastructure in navigable waters, such as bridges and docks, it is often necessary to build cofferdams under complex geological conditions to provide dry land construction conditions and ensure construction safety. However, the traditional steel sheet pile cofferdam construction technology faces many technical difficulties when faced with the complex geology of navigable waters and the need for extra-long steel sheet piles, including: 1) Low positioning accuracy of steel sheet piles: In traditional steel sheet pile cofferdam construction, the positioning of steel sheet piles mostly relies on simple guide devices or manual experience. Under complex geological conditions and navigable water environments, it is difficult to ensure the precise positioning of steel sheet piles, and problems such as deviation and tilt are prone to occur, affecting the structural stability and waterproof performance of the cofferdam. 2) Inconvenient installation and elevation adjustment of purlins: The installation method of purlins in the existing technology is relatively fixed, lacking a flexible adjustment mechanism, and it is difficult to adapt to the precise adjustment of the purlin elevation under different geological conditions and construction requirements, which in turn affects the construction quality and stability of the entire cofferdam. 3) It is difficult to control the installation elevation of the internal support: When installing the internal support, it is difficult to accurately control the elevation of the internal support with traditional methods, especially under complex geological and navigable water conditions. Factors such as water level changes and uneven geological settlement will affect the installation elevation of the internal support, thereby affecting the stress performance of the internal support and the overall safety of the cofferdam. 4) The steel sheet piles are not firmly fixed: For the fixation of extra-long steel sheet piles in complex geology, the existing technology may not fully consider the characteristics of different strata, resulting in insufficient fixation of the bottom of the steel sheet piles. Under the action of external forces such as water flow and waves, the steel sheet piles are prone to displacement and deformation, affecting the protection effect of the cofferdam. 5) Low construction efficiency: Due to the above-mentioned problems in positioning, installation, and fixation, frequent adjustments and corrections may be required during the construction process, resulting in slow construction progress and increased construction costs and construction period. 6) Poor ability to adapt to complex geological and navigation environments: Traditional steel sheet pile cofferdam construction technology lacks effective response measures when faced with complex geological conditions in navigable waters, such as large changes in silt layers and bearing layers, as well as external factors such as water flow and ship collisions, resulting in threats to the safety and stability of the cofferdam.

[0003] Due to the existence of the above technical difficulties, it is difficult to meet the needs of engineering construction, so a new cofferdam construction technology is needed to solve these problems. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide an ultra-long steel sheet pile cofferdam in navigable waters with complex geology and a construction method.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] A method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology comprises the following steps:

[0007] Step 1: Use the steel casing on the top of the pipe pile to connect and install the steel sheet pile and the positioning frame of the surrounding purlin; and construct a construction positioning frame for the steel sheet pile by installing the surrounding purlin on the positioning frame;

[0008] Step 2: drilling holes at the soil layer positions corresponding to the steel sheet piles; filling the holes with a sand-gravel mixture, and driving steel sheet piles to anchor the sand-gravel mixture;

[0009] Step 3: Install the inner support using the surrounding purlin; set a pontoon under the inner support, and temporarily fix the two ends of the pontoon to the steel sheet piles; adjust the elevation of the pontoon to match the surrounding purlin to control the installation elevation of the inner support;

[0010] Step 4: Concrete bottom construction.

[0011] Specifically, the positioning frame includes an upper horizontal plate and a lower horizontal plate; the enclosure purlin is installed on the lower horizontal plate; the enclosure purlin is provided with a lower protrusion; positioning blocks are provided on both sides of the lower protrusion; a movable block is movably installed between the lower protrusion and the lower horizontal plate; the enclosure purlin is installed using the lower protrusion and the positioning block, and the elevation of the enclosure purlin is adjusted using the movable block.

[0012] Specifically, in step one, an embedding block is installed on the upper part of the surrounding purlin and the lower part of the upper cross plate; an embedding rod is movably installed in the embedding block; the construction positioning frame of the steel sheet pile includes a first limit frame and a second limit frame; the embedding rod connects the first limit frame and the second limit frame through a cross-linking rod; the cross-linking rod is located at the side end of the steel sheet pile; the first limit frame and the second limit frame are provided with through holes, and the first limit rod and the second limit rod are movably installed in the through holes; a fixed block and an adjusting rod are provided on the upper cross plate, and the adjusting rod is used to adjust the vertical position of the first limit rod and the second limit rod; the length of the first limit rod and the second limit rod is longer than that of the first limit frame and the second limit frame; at least two cross-linking rods and the first limit frame, the second limit frame, the first limit rod and the second limit rod together constitute the construction positioning frame of the steel sheet pile.

[0013] Specifically, in step 2, the steel sheet piles are positioned and driven using a construction positioning frame, so that the bottom of the steel sheet piles is located in a sand-gravel mixture, and the sand-gravel mixture is anchored to the steel sheet piles to form a fixed end.

[0014] Specifically, in step three, after the steel sheet piles are driven, the inner support is installed using the purlin and the pontoon body; the pontoon body includes a float bag, a transverse frame and a longitudinal frame on the upper part of the float bag; the upper part of the float bag is provided with a water inlet pipe, and the water inlet pipe has a water inlet connected to the inside of the float bag; both sides of the pontoon body are temporarily fixedly connected to the steel sheet piles by fixing cables and fixing rings; the water volume in the float bag is adjusted by pumping water with the water inlet pipe, thereby adjusting the elevation of the pontoon body, so as to control the installation elevation of the inner support; after the installation of the inner support is completed, the pontoon body is removed.

[0015] An ultra-long steel sheet pile cofferdam for navigable waters with complex geology is constructed by the above-mentioned ultra-long steel sheet pile cofferdam for navigable waters with complex geology construction method.

[0016] The beneficial effects of the present invention are:

[0017] 1) The present invention can realize accurate positioning of steel sheet piles by constructing a construction positioning frame composed of a horizontal connecting rod, a first limit frame, a second limit frame, a first limit rod, a second limit rod, etc., especially the first limit rod and the second limit rod are longer, which can realize the positioning of steel sheet piles at deeper positions, effectively ensuring the accuracy of the steel sheet pile driving position and improving the molding quality of the overall structure of the cofferdam.

[0018] 2) The present invention utilizes the steel casing at the top of the pipe pile to form a positioning frame, and the purlin and the lower cross plate are stably installed by means of the lower protrusion and the positioning block. At the same time, the purlin elevation is flexibly adjusted with the movable block, which ensures the benchmark stability of the construction positioning from multiple levels and helps to accurately carry out the subsequent construction links.

[0019] 3) The bottom of the steel sheet pile involved in the present invention is located in a hole filled with a sand and gravel mixture, and the sand and gravel mixture is anchored to the steel sheet pile to form a firm fixed end, which enhances the foundation stability of the steel sheet pile under complex geological conditions, so that the entire cofferdam structure can better resist external forces such as water flow, and ensure the long-term stability of the cofferdam in the complex geological environment of navigable waters.

[0020] 4) After the steel sheet piles are driven, the present invention utilizes the surrounding purlins and the floating box to assist in the installation of the inner support, and the floating box can adjust the elevation to accurately control the installation elevation of the inner support. Multiple methods and multiple links ensure the reasonable installation of the inner support, further enhancing the overall stability of the entire cofferdam structure, so that it can better withstand external loads.

[0021] 5) A movable block is provided between the purlin and the lower cross plate involved in the present invention, which can flexibly adjust the elevation of the purlin to meet the elevation requirements under different construction site conditions, improve the adaptability to complex geological and site environmental changes during the construction process, and avoid construction obstacles caused by factors such as site differences.

[0022] 6) The present invention sets a water inlet pipe on the pontoon body, which can adjust the water volume in the float bag by pumping and releasing water, and then adjust the elevation of the pontoon body, so as to flexibly control the installation elevation of the inner support; this adjustable method is convenient for accurate installation of the inner support under different working conditions and construction stages, and enhances the flexibility of the entire construction process to cope with complex navigable water environments and different construction requirements.

[0023] 7) The present invention clarifies a reasonable construction sequence, such as first carrying out the purlin construction, etc., and each construction step is connected in an orderly and clear manner, which helps construction personnel to construct efficiently according to the process, reduce confusion and errors in construction, and ensure construction progress and quality; the design of related structures such as the construction positioning frame and the construction steps are all centered on key links such as ensuring the accurate driving of steel sheet piles and the reasonable installation of internal supports, ensuring construction quality from multiple aspects, reducing rework caused by construction deviations, etc., and indirectly improving the overall construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0025] Figure 1 This is a schematic diagram of drilling holes for steel sheet piles according to the present invention;

[0026] Figure 2 This is a schematic diagram of the construction of purlins and steel sheet piles;

[0027] Figure 3 for Figure 2 Schematic diagram of the plan view of the positioning frame for medium steel sheet pile construction;

[0028] Figure 4 This is a schematic diagram of the internal support installation;

[0029] Explanation of the reference numerals: 1. steel sheet pile; 2. cast-in-place pile; 3. silt layer; 4. bearing layer; 5. hole; 6. sand-gravel mixture; 7. steel casing; 8. bottom cover; 9. enclosure space; 10. surrounding purlin; 11. upper horizontal plate; 12. lower horizontal plate; 13. lower protrusion; 14. movable block; 15. positioning block; 16. positioning bolt; 17. first limit frame; 18. first limit rod; 19. second limit frame; 20. second limit rod; 21. adjusting rod; 22. fixed block; 23. embedded block; 24. embedded rod; 25. horizontal connecting rod; 26. inner support; 27. floating bag; 29. ​​transverse frame; 30. longitudinal frame; 31. water inlet pipe; 32. water inlet; 33. fixing rope; 34. fixing ring. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0031] Embodiment 1

[0032] As an example, see Figure 1-4 As shown, in this embodiment, a construction method for an ultra-long steel sheet pile cofferdam in a navigable water area with complex geology is provided, comprising the following steps:

[0033] Step 1: Combine Figure 1 and Figure 2 As shown, the cofferdam includes cast-in-place piles 2, steel sheet piles 1 and a surrounding space 9 formed by the steel sheet piles 1. The cast-in-place piles 2 have steel casings 7 on their upper parts. The steel casings 7 on the top of the pipe piles are used to connect and install the steel sheet piles 1 and the positioning frame for the surrounding purlins 10. The construction positioning frame for the steel sheet piles 1 is constructed by installing the surrounding purlins 10 on the positioning frame. Figure 2 As shown, the purlin 10 is constructed before the steel sheet piles 1; the steel casing 7 on the top of the pipe pile is used to connect the steel sheet piles 1 and the purlin 10 to form a positioning frame, and the positioning frame includes an upper cross plate 11 and a lower cross plate 12, and the purlin 10 is installed on the lower cross plate 12; the purlin 10 has a lower protrusion 13, and positioning blocks 15 are provided on both sides of the lower protrusion 13. A plurality of movable blocks 14 are movably installed between the lower protrusion 13 and the lower cross plate 12. The purlin 10 can be stably installed by using the lower protrusion 13 and the positioning blocks 15, and the elevation of the purlin 10 can be flexibly adjusted by using the movable blocks 14, which ensures the benchmark stability of the construction positioning from multiple levels and helps to accurately carry out the subsequent construction links.

[0034] Step 2: drilling holes 5 at the soil layer positions corresponding to the steel sheet piles 1; filling the holes 5 with a sand-gravel mixture 6, and driving the steel sheet piles 1 and the sand-gravel mixture 6 for anchoring.

[0035] Step 3: Use the purlin 10 to install the inner support 26; set a pontoon under the inner support 26, and temporarily fix both ends of the pontoon to the steel sheet piles 1; adjust the elevation of the pontoon to match the purlin 10, and control the installation elevation of the inner support 26.

[0036] Step 4: Construction of concrete bottom seal 8.

[0037] This embodiment clarifies a reasonable construction sequence, so that each construction step is connected in an orderly and clear manner, which helps construction personnel to carry out construction efficiently according to the process, reduces confusion and errors in construction, and ensures construction progress and quality.

[0038] Embodiment 2

[0039] As another embodiment, this embodiment 2 is proposed on the basis of embodiment 1 and includes the following steps:

[0040] Step 1: Use the steel casing 7 on the top of the pipe pile to connect and install the steel sheet pile 1 and the positioning frame of the surrounding purlin 10; construct a construction positioning frame for the steel sheet pile 1 by installing the surrounding purlin 10 on the positioning frame; Figure 2 As shown, an embedded block 23 is installed at the upper part of the surrounding purlin 10 and the lower part of the upper cross plate 11, and an embedded rod 24 is movably installed in the embedded block 23. The embedded rod 24 connects the first limit frame 17 and the second limit frame 19 through a cross connecting rod 25. The cross connecting rod 25 is located at the side end of the steel sheet pile 1 to be constructed to avoid position conflict. The first limit frame 17 and the second limit frame 19 have through holes inside, and the first limit rod 18 and the second limit rod 20 are movably installed in the through holes; at the same time, a fixed block 22 and an adjusting rod 21 are provided on the upper cross plate 11 for adjusting the vertical position of the first limit rod 18 and the second limit rod 20. The thickness of the first limiting rod 18 and the second limiting rod 20 is longer than that of the first limiting frame 17 and the second limiting frame 19, so that the steel sheet pile 1 can be positioned at a deeper position; at least two horizontal connecting rods 25 and the first limiting frame 17, the second limiting frame 19, the first limiting rod 18, and the second limiting rod 20 together constitute a construction positioning frame for the steel sheet pile 1, so as to achieve precise positioning of the steel sheet pile 1, especially the first limiting rod 18 and the second limiting rod 20 are longer, so as to achieve positioning of the steel sheet pile 1 at a deeper position, effectively ensure the accuracy of the driving position of the steel sheet pile 1, and improve the molding quality of the overall structure of the cofferdam.

[0041] Step 2: drilling holes 5 at the soil layer positions corresponding to the steel sheet piles 1; filling the holes 5 with a sand-gravel mixture 6, and driving the steel sheet piles 1 and the sand-gravel mixture 6 for anchoring;

[0042] Step 3: Use the purlin 10 to install the inner support 26; set a pontoon under the inner support 26, and temporarily fix the two ends of the pontoon to the steel sheet piles 1; adjust the elevation of the pontoon to match the purlin 10, and control the installation elevation of the inner support 26;

[0043] Step 4: Construction of concrete bottom seal 8.

[0044] The design of the relevant structures of the construction positioning frame and the construction steps mentioned in this embodiment is carried out around key links such as ensuring the accurate driving of the steel sheet pile 1 and the reasonable installation of the internal support, which ensures the construction quality from many aspects, reduces rework caused by construction deviations, and indirectly improves the overall construction efficiency.

[0045] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0046] Embodiment 3

[0047] As another embodiment, this embodiment 3 is proposed on the basis of embodiment 1, and includes the following steps:

[0048] Step 1: Use the steel casing 7 on the top of the pipe pile to connect and install the steel sheet pile 1 and the positioning frame of the surrounding purlin 10; and construct a construction positioning frame for the steel sheet pile 1 by installing the surrounding purlin 10 on the positioning frame.

[0049] Step 2: drill a hole 5 at the soil layer corresponding to the steel sheet pile 1; fill the hole 5 with a sand-gravel mixture 6, and use the construction positioning frame of the steel sheet pile 1 to position and install the steel sheet pile 1, so that the bottom of the steel sheet pile 1 is located in the sand-gravel mixture 6, and the sand-gravel mixture 6 is anchored to the steel sheet pile 1 to form a fixed end; and the sand-gravel mixture 6 is anchored to the steel sheet pile 1 to form a firm construction positioning frame composed of a horizontal connecting rod 25, a first limit frame 17, a second limit frame 19, a first limit rod 18, a second limit rod 20, etc.

[0050] Step 3: Use the purlin 10 to install the inner support 26; set a pontoon under the inner support 26, and temporarily fix both ends of the pontoon to the steel sheet piles 1; adjust the elevation of the pontoon to match the purlin 10, and control the installation elevation of the inner support 26.

[0051] Step 4: Construction of concrete bottom seal 8.

[0052] The provision of the construction positioning frame in this embodiment enhances the foundation stability of the steel sheet pile 1 under complex geological conditions, so that the entire cofferdam structure can better resist external forces such as water flow, and ensure the long-term stability of the cofferdam in the complex geological environment of navigable waters.

[0053] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0054] Embodiment 4

[0055] As another embodiment, this embodiment 4 is proposed on the basis of embodiment 1, and includes the following steps:

[0056] Step 1: Use the steel casing 7 on the top of the pipe pile to connect and install the steel sheet pile 1 and the positioning frame of the surrounding purlin 10; construct a construction positioning frame for the steel sheet pile 1 by installing the surrounding purlin 10 on the positioning frame;

[0057] Step 2: drilling holes 5 at the soil layer positions corresponding to the steel sheet piles 1; filling the holes 5 with a sand-gravel mixture 6, and driving the steel sheet piles 1 and the sand-gravel mixture 6 for anchoring;

[0058] Step 3, using the purlin 10 to install the inner support 26; set a buoyancy box under the inner support 26, and temporarily fix the two ends of the buoyancy box to the steel sheet piles 1; adjust the elevation of the buoyancy box to cooperate with the purlin 10 to control the installation elevation of the inner support 26; after the steel sheet piles 1 are driven, use the purlin 10 and the buoyancy box to install the inner support 26; the buoyancy box includes a float bag 27, a transverse frame 29 and a longitudinal frame 30 on the upper part of the float bag 27; the upper part of the float bag 27 is provided with a water inlet pipe 31, and the water inlet pipe 31 has a water inlet 32 ​​connected to the inside of the float bag 27; the two sides of the buoyancy box are temporarily fixedly connected to the steel sheet piles 1 by fixing ropes 33 and fixing rings 34; use the water inlet pipe 31 to pump and release water to adjust the water volume in the float bag 27, thereby adjusting the elevation of the buoyancy box, so as to control the installation elevation of the inner support 26; after the installation of the inner support 26 is completed, the buoyancy box is removed.

[0059] Step 4: Construction of concrete bottom seal 8.

[0060] In this embodiment, after the steel sheet pile 1 is driven, the inner support 26 is installed by using the purlin 10 and the floating box body, and the floating box body can adjust the elevation to accurately control the installation elevation of the inner support 26. The reasonable installation of the inner support 26 is guaranteed in multiple ways and multiple links, which further enhances the overall stability of the entire cofferdam structure and enables it to better withstand external loads. At the same time, a movable block is provided between the purlin 10 and the lower cross plate 12, which can flexibly adjust the elevation of the purlin 10, can adapt to the elevation requirements under different construction site conditions, improve the adaptability to complex geological and site environmental changes during the construction process, and avoid construction obstacles caused by factors such as site differences. In order to achieve flexible control of the installation elevation of the inner support 26, an inlet pipe 31 is provided on the floating box body, and the water volume in the floating bag 27 can be adjusted by pumping water, thereby adjusting the elevation of the floating box body; this adjustable method facilitates the accurate installation of the inner support 26 under different working conditions and construction stages, and enhances the flexibility of the entire construction process to cope with complex navigable water environments and different construction requirements.

[0061] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0062] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology, characterized in that: The steps include: Step 1: Use the steel casing on the top of the pipe pile to connect and install the steel sheet pile and the positioning frame of the surrounding purlin; and construct a construction positioning frame for the steel sheet pile by installing the surrounding purlin on the positioning frame; Step 2: drilling holes at the soil layer positions corresponding to the steel sheet piles; filling the holes with a sand-gravel mixture, and driving steel sheet piles to anchor the sand-gravel mixture; Step 3: Install the inner support using the surrounding purlin; set a pontoon under the inner support, and temporarily fix the two ends of the pontoon to the steel sheet piles; adjust the elevation of the pontoon to match the surrounding purlin to control the installation elevation of the inner support; Step 4: Concrete bottom construction.

2. The method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology according to claim 1 is characterized in that: The positioning frame includes an upper horizontal plate and a lower horizontal plate; the enclosure purlin is installed on the lower horizontal plate; the enclosure purlin is provided with a lower protrusion; positioning blocks are provided on both sides of the lower protrusion; a movable block is movably installed between the lower protrusion and the lower horizontal plate; the enclosure purlin is installed using the lower protrusion and the positioning block, and the elevation of the enclosure purlin is adjusted using the movable block.

3. The method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology according to claim 1 is characterized in that: In step one, an embedding block is installed on the upper part of the surrounding purlin and the lower part of the upper cross plate; an embedding rod is movably installed in the embedding block; the construction positioning frame of the steel sheet pile includes a first limit frame and a second limit frame; the embedding rod connects the first limit frame and the second limit frame through a cross-linking rod; the cross-linking rod is located at the side end of the steel sheet pile; the first limit frame and the second limit frame are provided with through holes, and the first limit rod and the second limit rod are movably installed in the through holes; a fixed block and an adjusting rod are provided on the upper cross plate, and the adjusting rod is used to adjust the vertical position of the first limit rod and the second limit rod; the length of the first limit rod and the second limit rod is longer than that of the first limit frame and the second limit frame; at least two cross-linking rods and the first limit frame, the second limit frame, the first limit rod and the second limit rod together constitute the construction positioning frame of the steel sheet pile.

4. The method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology according to claim 1 is characterized in that: In step 2, the steel sheet piles are positioned and driven using a construction positioning frame, so that the bottom of the steel sheet piles is located in the sand and gravel mixture, and the sand and gravel mixture are anchored to the steel sheet piles to form a fixed end.

5. The method for constructing an ultra-long steel sheet pile cofferdam in navigable waters with complex geology according to claim 1 is characterized in that: In step three, after the steel sheet piles are driven, the inner support is installed using the purlin and the pontoon body; the pontoon body includes a float bag, a transverse frame and a longitudinal frame on the upper part of the float bag; the upper part of the float bag is provided with a water inlet pipe, and the water inlet pipe has a water inlet connected to the inside of the float bag; both sides of the pontoon body are temporarily fixedly connected to the steel sheet piles by fixing cables and fixing rings; the water volume in the float bag is adjusted by pumping water with the water inlet pipe, thereby adjusting the elevation of the pontoon body, so as to control the installation elevation of the inner support; after the installation of the inner support is completed, the pontoon body is removed.

6. An ultra-long steel sheet pile cofferdam for navigable waters with complex geology, characterized in that: The super-long steel sheet pile cofferdam is constructed by the construction method for complex geological conditions in navigable waters as described in any one of claims 1 to 5.

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