Deepwater steel pipe pile cofferdam and construction method thereof

Abstract

The application belongs to the technical field of underwater foundation construction, and particularly relates to a deep-water steel pipe pile cofferdam and a construction method thereof, which comprises a prefabricated hoisting box, the prefabricated hoisting box comprises side plates and corner plates, a plurality of side plates are spliced with each other and arranged on four sides of a lower hoisting frame, and the corner positions between the side plates of the four sides are connected through the corner plates; the lower hoisting frame comprises a first cross beam and a second cross beam, the bottom side of the side plate is provided with a first bottom beam and two second bottom beams, a sliding insertion groove is formed between the two second bottom beams, and the bottom side of the corner plate is provided with a matching beam. The side plate along the length direction of the first cross beam is supported on the first cross beam through the first bottom beam, the side plate along the length direction of the second cross beam is supported in the side groove of the second cross beam through the second bottom beam, and the corner plate extends into the sliding insertion groove through the matching beam. The structure converts the complex underwater connection operation into accurate positioning and support on the preset track, thereby ingeniously solving the problem of underwater rapid and reliable connection.

Description

Technical Field

[0001] This invention belongs to the field of underwater foundation construction technology, and in particular relates to a deep-water steel pipe pile cofferdam and its construction method. Background Technology

[0002] With the continuous advancement of transportation infrastructure construction, the number of cross-river and cross-sea bridge projects is increasing, making deep-water foundation construction technology a crucial aspect of bridge construction. In deep-water bridge foundation construction, the pier cap, as a key load-bearing component connecting the pile foundation and the pier, directly affects the overall safety and durability of the bridge due to its construction quality. However, pier cap construction in deep-water environments faces multiple challenges, including water flow impact, water level changes, and difficulties in underwater operations. Creating a dry construction environment underwater has become a core engineering challenge.

[0003] Steel cofferdam technology has emerged to address this need. Its basic principle is to utilize pre-constructed bored piles and steel casings as load-bearing and guiding structures. A steel cofferdam with a bottom plate is suspended from the pile foundation via a hoisting system, forming a closed water-retaining structure. Water is then stopped at the bottom by pouring bottom-sealing concrete, and finally, the water inside the cofferdam is pumped out, creating conditions for the construction of the pile cap. Compared to traditional bed-type cofferdams, bottomed steel cofferdams are not limited by water depth or riverbed conditions, require less steel, and have a shorter construction period, making them particularly suitable for high-pile pile cap construction.

[0004] The steel caisson cofferdam is tall and heavy. In addition to using a suspension system fixed to the bored piles to suspend the entire steel caisson cofferdam, it is also necessary to ensure a reliable connection between the bottom side (water-facing part) of the steel caisson cofferdam and the suspension system. The existing technology has the following drawback: the connection between the underwater part and the suspension system during the splicing of the steel caisson cofferdam lacks a quick and accurate positioning method.

[0005] Currently, the installation of steel caisson cofferdams mainly involves in-situ assembly: an assembly platform needs to be erected within the pier area, or a suspended installation method is used. This results in a large amount of on-site work, complex construction techniques, and a long cycle. In particular, the connection between the water-covered part of the bottom of the steel caisson cofferdam and the suspension system is crucial. Since it is an underwater operation, the connection between the bottom of the steel caisson cofferdam and the suspension system needs to be achieved quickly, reliably, and firmly. However, the current cofferdam structure is bulky and complex, and the bottom of the steel caisson cofferdam is basically composed of large keels (H-shaped steel), making construction quite difficult. Summary of the Invention

[0006] In view of the technical problems existing in the background art, the present invention provides a deep-water steel pipe pile cofferdam and its construction method.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows: A deep-water steel pipe pile cofferdam, comprising: A steel casing is inserted into the bedrock at the bottom of the riverbed. Reinforced concrete piles are then drilled and poured inside the steel casing. Support columns are pre-embedded at the top of the reinforced concrete piles. A suspension system, comprising an upper suspension and a lower suspension, wherein the upper and lower suspensions are connected by a plurality of suspension rods, and the upper suspension is mounted on a support column; A prefabricated caisson includes a base plate, side plates, and corner plates. Several base plates are spliced ​​together and mounted on a lower suspension frame. The base plates are fitted around the outside of the steel casing. Several side plates are spliced ​​together and mounted on the four sides of the lower suspension frame. The corners between the side plates on the four sides are connected by corner plates. The base plate, side plates, and corner plates are spliced ​​together to form a prefabricated caisson with an open top. The lower suspension frame includes a number of first and second crossbeams arranged in a crisscross pattern. The upper sides of the first crossbeams are tightly fixed with second crossbeams, and each pair of second crossbeams forms a group. Both the first and second crossbeams are set in an "I" shape. The side plate has a first bottom beam on its bottom side, and second bottom beams are symmetrically arranged on both sides of the first bottom beam. Both the first bottom beam and the second bottom beam are set in the shape of "I". The second bottom beam is located inside the first bottom beam, and both ends of the second bottom beam extend to the outside of the first bottom beam so that a sliding slot is formed between the two second bottom beams; the corner plate has a mating beam on its bottom side. The side plate along the length of the first crossbeam is supported on the upper end face of the first crossbeam by the first bottom beam, and the side plate along the length of the second crossbeam is supported in the side groove of the second crossbeam by the second bottom beam; the bottom side of the corner plate is supported on the second crossbeam, and the mating beam extends into the sliding slot.

[0008] Optionally, a slider may be selectively configured in the sliding slot of the second bottom beam. Several connecting holes are opened on both sides of the second bottom beam along the length direction. Two first locking rods are internally threaded to the slider. The two first locking rods pass through the connecting holes of the two second bottom beams on the upper side of the first crossbeam respectively, connecting and fixing the two adjacent second bottom beams.

[0009] Optionally, the two second crossbeams in each group are set at a fixed distance apart so that an installation groove is formed between the two second crossbeams, and a locking block is provided in the installation groove; a guide part is provided in the middle of one side of the locking block, and abutment parts are symmetrically provided on both sides of the guide part. The guide part is provided in the installation groove, and the abutment parts abut against the second bottom beam inside the second crossbeam.

[0010] Optionally, the two ends of the second crossbeam are respectively provided with first locking holes, and the abutting part and the guide part are respectively provided with second locking holes. The first locking holes and the second locking holes are connected by a second locking rod.

[0011] Optionally, the abutting portion of one side of the locking block installed on the bottom side of the corner plate abuts against the mating beam of the corner plate.

[0012] Optionally, the mating beam has several through-holes, and a positioning pin is fitted in each of the through-holes. The positioning pin passes through the connecting hole of the second bottom beam.

[0013] Optionally, the side plate has a plurality of first mounting holes evenly distributed on its upper side and vertical sides, and the corner plate has a plurality of second mounting holes evenly distributed on its upper side and vertical sides.

[0014] Optionally, a semi-circular groove is provided on one side of the base plate to avoid the steel casing, and a notch is provided on the other side of the base plate to avoid the lifting rod.

[0015] Optionally, the steel casing is provided with several bracket support structures, and the bottom end of the lower hanger is supported on the bracket support structures.

[0016] A construction method for a deep-water steel pipe pile cofferdam, comprising the following steps: S1, Install steel casing: Use a floating gantry crane to insert the steel casing into the bedrock at the bottom of the riverbed, ensuring that the top of the steel casing extends above the water surface; S2, Install the drilling platform: Install the drilling platform on the upper side of the steel casing and drill in batches; S3, Pile foundation construction: Cast reinforced concrete piles inside steel casings, and pre-embed support columns at the top of the reinforced concrete piles; remove the drilling platform after the pile foundation construction is completed. S4, Install the hanger system and prefabricated caisson: Install the upper hanger and hanger rod on the support column, then install the lower hanger, adjust the elevation and install the bottom plate, first floor side plate and corner plate, and pour the bottom sealing concrete; S5, High Pile Foundation Casting: The water in the precast caisson is pumped out, the steel casing above the bottom plate is cut off, and then the first-floor foundation construction is carried out.

[0017] The present invention has the following advantages and beneficial effects: By optimizing the structural design of the gantry system and prefabricated caissons, it is easier to quickly and accurately position and assemble the prefabricated caissons, and to reliably support and fix the prefabricated caissons and gantry system underwater, thus reducing the difficulty of underwater installation operations.

[0018] After the side plates and corner plates are assembled into a ring-shaped cofferdam, the side plates can be selectively installed according to their positions: the side plates along the length of the first crossbeam are supported on the upper surface of the first crossbeam by the first bottom beam; the side plates along the length of the second crossbeam are supported in the side groove of the second crossbeam by the second bottom beam. Using the same side plate structure, stable limiting support can be achieved in any orientation. The bottom side of the corner plate is supported on the second crossbeam, and the cooperating beam extends into the sliding slot, thus completing the rapid positioning and installation of the corner plates. This structure transforms the complex underwater connection operation into precise positioning and support on a pre-set track, cleverly solving the problem of rapid and reliable underwater connection. It ensures the rapid connection of the precast caisson and the gantry system underwater, while also guaranteeing the reliability of the entire precast caisson connection and the reliability of subsequent foundation pouring construction. Attached Figure Description

[0019] Figure 1 This is one of the structural diagrams of the deep-water steel pipe pile cofferdam of the present invention; Figure 2 This is the second structural diagram of the deep-water steel pipe pile cofferdam of the present invention; Figure 3 for Figure 1 A magnified view of a portion of point a. Figure 4 for Figure 1 A magnified view of a section at point b in the middle; Figure 5 for Figure 1 A magnified view of a section at point c in the middle; Figure 6 for Figure 2 A magnified view of a portion at point d in the middle; Figure 7 for Figure 2 A magnified view of a section at point e in the middle; Figure 8 for Figure 2 A magnified view of a portion at point f. Figure 9 for Figure 8 Structure diagram of removing the lock block; Figure 10 for Figure 7 Structure diagram of removing the lock block; Figure 11 This is one of the structural diagrams of the prefabricated caisson and hanger system of the present invention; Figure 12 This is the second structural diagram of the prefabricated caisson and hanger system of the present invention; Figure 13 This is one of the structural diagrams of the side plate of the present invention; Figure 14 This is the second structural diagram of the side plate of the present invention; Figure 15This is the third structural diagram of the side plate of the present invention; Figure 16 This is one of the structural diagrams of the corner plate of the present invention; Figure 17 This is the second structural diagram of the corner plate of the present invention; Figure 18 This is a structural diagram of the base plate of the present invention; Figure 19 This is a structural diagram of the locking block of the present invention.

[0020] Attached reference numerals: 1-Bedrock surface at the bottom of the riverbed, 2-Steel casing, 21-Corner support structure, 22-Vertical reinforcement, 23-Support column, 3-Upper hanger, 31-First hanging beam, 32-Second hanging beam, 33-Horizontal plate, 4-Hanging rod, 41-Locking nut, 5-Lower hanger, 51-First horizontal beam, 52-Second horizontal beam, 53-First locking hole, 54-Installation groove, 6-Side plate, 61-First bottom beam, 62-Second bottom beam Beam, 621-sliding slot, 622-connecting hole, 63-slider, 64-first locking rod, 65-first mounting hole, 7-angle plate, 71-pad plate, 72-fitting beam, 721-pin hole, 73-positioning pin, 74-second mounting hole, 8-base plate, 81-semi-circular groove, 82-notch, 9-locking block, 91-guide part, 92-abutting part, 93-second locking hole, 94-second locking rod, 95-stiffening plate. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] Example like Figures 1 to 19 As shown, a deep-water steel pipe pile cofferdam includes: a steel casing 2, a hanging system, and a prefabricated caisson.

[0024] like Figures 1-3 As shown, the bottom end of the steel casing 2 is inserted into the bedrock surface 1 at the bottom of the riverbed. A hole is drilled along the inside of the steel casing 2 and a reinforced concrete pile is poured. A supporting column 23 is pre-embedded at the top of the reinforced concrete pile. Vertical steel bars 22 are also pre-embedded at the top of the reinforced concrete pile.

[0025] like Figures 1-3 , Figure 11 and Figure 12 As shown, the hanger system includes an upper hanger 3 and a lower hanger 5, which are connected by several hanger rods 4. The upper hanger 3 is installed on the support column 23.

[0026] like Figures 1-3 , Figure 11 and Figure 12 As shown, the upper suspension frame 3 includes several crisscrossing first suspension beams 31 and second suspension beams 32. Four supporting columns 23 are pre-embedded in the top of each steel casing 2. The bottom sides of the first suspension beams 31 are welded and fixed to the supporting columns 23, while the second suspension beams 32 are welded and fixed to the first suspension beams 31. Every two second suspension beams 32 form a group, with the two second suspension beams 32 in the same group spaced at a fixed distance and fixed by several horizontal plates 33. The suspension rod 4 extends downwards through the horizontal plates 33, and a locking nut 41 is provided on the suspension rod 4 to secure it to the second suspension beams 32.

[0027] like Figures 1-3 , Figure 11 and Figure 12 As shown, the lower hanger 5 includes several first crossbeams 51 and second crossbeams 52 arranged in a crisscross pattern. The upper sides of the first crossbeams 51 are tightly fixed with second crossbeams 52. Two second crossbeams 52 form a group, with the two second crossbeams 52 in the same group spaced at a fixed distance and fixed by welding with several horizontal plates 33. Both the first crossbeams 51 and the second crossbeams 52 are shaped like the letter "I". The bottom end of the hanger rod 4 extends into the interior of the same group of second crossbeams 52. A locking nut 41 is also provided on the bottom side of the hanger rod 4 to suspend the lower hanger 5 (first crossbeams 51 and second crossbeams 52) on the hanger rod 4.

[0028] like Figures 1 to 18 As shown, the prefabricated caisson includes a base plate 8, side plates 6, and corner plates 7. Figure 12 As shown, several base plates 8 are spliced ​​together and mounted on the lower hanger 5. The base plates 8 are fitted around the outer side of the steel casing 2 to avoid obstructing the steel casing 2. Figure 11 As shown, several side plates 6 are spliced ​​together and set on the four sides of the lower gantry 5. The corner positions between the side plates 6 on the four sides are connected by the corner plates 7. The bottom plate 8, side plates 6 and corner plates 7 are spliced ​​together to form a prefabricated gantry with an open top, i.e., a cofferdam.

[0029] like Figures 13-15As shown, a first bottom beam 61 is provided on the bottom side of the side plate 6, and second bottom beams 62 are symmetrically arranged on both sides of the first bottom beam 61. Both the first bottom beam 61 and the second bottom beam 62 are configured in an "I" shape. The second bottom beams 62 are welded inside the first bottom beam 61 to achieve the limiting installation of the second bottom beams 62. This structure firstly ensures the strength of the overall bottom support structure, and secondly, it allows for convenient connection from multiple directions. The two ends of the second bottom beams 62 extend to the outside of the first bottom beam 61, meaning that the length of the second bottom beams 62 is longer than that of the first bottom beam 61, so that a sliding slot 621 is formed between the two second bottom beams 62. Because the two second bottom beams 62 have a fixed interval, a sliding slot 621 can be formed for subsequent connection.

[0030] like Figure 16 and Figure 17 As shown, a pad 71 is provided on the bottom side of the corner plate 7, and a matching beam 72 is provided on the bottom side of the pad 71. The matching beam 72 can be set in the shape of "I".

[0031] like Figure 2 , Figure 6 and Figure 7 As shown, the side plate 6 along the length of the first crossbeam 51 is supported on the upper surface of the first crossbeam 51 by the first bottom beam 61. That is, the side plate 6 at both ends of the first crossbeam 51 is supported and fixed by the first bottom beam 61 on the bottom side of the side plate 6. At this time, the first bottom beam 61 is directly supported and fixed on the first crossbeam 51, while the second bottom beam 62 is not supported. At this time, the inner side of the second bottom beam 62 is limited by the side wall of the second crossbeam 52. When the side plate 6 is installed in place (the side plate 6 is installed tightly against the bottom plate 8), the inner side of the second bottom beam 62 abuts against the side wall of the second crossbeam 52 to achieve limitation.

[0032] like Figure 2 , Figure 7 and Figure 8 As shown, the side plate 6 along the length of the second crossbeam 52 is supported within the side groove of the second crossbeam 52 by the second bottom beam 62. That is, the side plate 6 at both ends of the second crossbeam 52 is supported and fixed by the second bottom beam 62 on the bottom side of the side plate 6. Since the second crossbeam 52 is designed in an I-beam shape, both ends of the second bottom beam 62 are directly supported and fixed within the inner groove of the second crossbeam 52, while the first bottom beam 61 is not supported.

[0033] Through the above structural design, the side plate 6, with the same structure, can be stably installed on different sides. When installing the prefabricated caisson, the caisson is submerged to a depth of about one meter in the water. Therefore, in this case, this structure allows for the rapid positioning and installation of the side plate 6 in any orientation, ensuring its precise support on the lower caisson 5. The same side plate can be supported by different bottom beams in two orthogonal directions. The interchangeability brought about by the structural symmetry reduces the difficulty of distinguishing directions underwater.

[0034] like Figure 7 and Figure 10 As shown, the bottom side of the corner plate 7 is supported on the second crossbeam 52, and the matching beam 72 extends into the sliding slot 621. This allows for precise positioning and installation of the corner plate 7, thereby enabling a quick connection between the corner plate 7 and the side plates 6 on both sides.

[0035] like Figure 6 , Figures 13-15 As shown, a slider 63 can be selectively configured in the sliding slot 621 of the second bottom beam 62. Several connecting holes 622 are opened on both sides of the second bottom beam 62 along the length direction. Two first locking rods 64 are internally threaded to the slider 63. The two first locking rods 64 pass through the connecting holes 622 of the two second bottom beams 62 on the upper side of the first crossbeam 51, respectively, to connect and fix the two adjacent second bottom beams 62.

[0036] In this design, after the side plates 6 at both ends of the first crossbeam 51 are supported and fixed, the second bottom beam 62 on the bottom side of the two sets of side plates 6 has a fixed interval. To achieve a reliable connection between the two sets of side plates 6, a sliding slider 63 is used. Before installation, the slider 63 is stored inside the second bottom beam 62 (e.g., Figure 14 As shown), after the side plate 6 is installed, adjust the position of the slider 63 so that the slider 63 extends into the sliding slots 621 of the two adjacent sets of second bottom side beams, and then make a stable connection through the first locking rod 64.

[0037] like Figure 9 As shown, the two second crossbeams 52 in each group are spaced at a fixed distance, so that a mounting groove 54 is formed between the two second crossbeams 52. Figure 8 As shown, a locking block 9 is fitted inside the mounting groove 54 to limit and fix the side plate 6. Figure 8 and Figure 19As shown, a guide portion 91 is provided in the middle of one side of the locking block 9, and abutment portions 92 are symmetrically arranged on both sides of the guide portion 91. The abutment portions 92 are shaped like an I-beam. The guide portion 91 is fitted into the mounting groove 54, and the abutment portions 92 abut against the second bottom beam 62 inside the second crossbeam 52. The guide portion 91 and the abutment portions 92 are spaced apart, and the guide portion 91 and the abutment portions 92 are respectively provided with stiffening plates 95 to strengthen the connection. With this design, the side plates 6 at both ends of the second crossbeam 52 can be limited and fixed by the locking block 9. By inserting the guide portion 91 of the locking block 9 into the mounting groove 54 inside the second crossbeam 52, and making the abutment portion 92 abut against the second bottom beam 62 of the side plate 6, precise and reliable limiting is achieved.

[0038] like Figure 4 , Figure 8 , Figure 9 and Figure 19 As shown, the second crossbeam 52 is further provided with first locking holes 53 through both ends, and second locking holes 93 through the abutment part 92 and the guide part 91. The first locking holes 53 and the second locking holes 93 are connected by a second locking rod 94, so that the second crossbeam 52 can be locked and fixed, thus completing the limiting and fixing of the side plate 6.

[0039] like Figure 7 and Figure 10 As shown, furthermore, the abutting part 92 on one side of the locking block 9 installed on the bottom side of the corner plate 7 abuts against the mating beam 72 of the corner plate 7. In this way, the locking block 9 can be used to simultaneously install and fix the side plate 6 and the corner plate 7. Multiple constraints are achieved with a single part, reducing underwater operation steps.

[0040] In this invention, all positioning is achieved by the natural formation of guide surfaces by the flanges / webs of the I-beams, eliminating the need for measurement or manual alignment.

[0041] like Figure 7 and Figure 10 As shown, furthermore, the mating beam 72 has several through-holes 721, and a positioning pin 73 is fitted into each of the through-holes 721. The positioning pin 73 passes through the connecting hole 622 of the second bottom beam 62. This further enhances the connection stability between the mating beam 72 and the second bottom beam 62.

[0042] Figures 13-15 As shown, the side plate 6 has several first mounting holes 65 evenly distributed on its upper side and vertical sides, and the corner plate 7 has several second mounting holes 74 evenly distributed on its upper side and vertical sides. When adjacent side plates 6 are installed, they are fixed by inserting bolts into the first mounting holes 65; when the corner plate 7 and the side plate 6 are installed, they are fixed by inserting bolts by aligning the first mounting holes 65 and the second mounting holes 74.

[0043] like Figure 18As shown, a semi-circular groove 81 is provided on one side of the base plate 8 to avoid the steel casing 2, and is used to install it tightly against the outside of the steel casing 2. A notch 82 is provided on the other side of the base plate 8 to avoid the lifting rod 4.

[0044] Figures 1-9 As shown, the steel casing 2 is equipped with several corbel support structures 21, and the bottom of the lower hanger 5 is supported on the corbel support structures 21. This design allows the corbel support structures 21 to be used to install the drilling platform in the early stages, facilitating drilling and pile foundation pouring. Later, after the drilling platform is dismantled, they can support the installation of the lower hanger 5. This suspension combined with bottom-side support method for installing the deep-water steel pipe pile cofferdam further enhances its strength and stability.

[0045] A construction method for a deep-water steel pipe pile cofferdam, comprising the following steps: S1, Install steel casing 2: Use a floating gantry crane to insert the steel casing 2 into the bedrock surface 1 at the bottom of the riverbed, ensuring that the top of the steel casing 2 extends above the water surface. The floating gantry crane can be assembled on a double-guided vessel as a lifting device for the underwater foundation. Use the double-guided vessel to install the steel casing 2, and use a vibratory hammer to assist in sinking the steel casing 2 to the bedrock.

[0046] S2, Install the drilling platform: Install the drilling platform on the upper side of the steel casing 2 using the bracket support structure 21, and carry out drilling in batches.

[0047] S3, Pile foundation construction: Cast reinforced concrete piles are poured inside the steel casing 2, and support columns 23 are pre-embedded on the top of the reinforced concrete piles. After the pile foundation construction is completed, the drilling platform is removed.

[0048] S4, Install the scaffolding system and precast caisson: Install the upper scaffolding 3 and scaffolding rod 4 on the supporting column 23, then install the lower scaffolding 5. After adjusting the elevation, install the base plate 8, the first-floor side plate 6, and the corner plate 7, and pour underwater bottom sealing concrete using the tremie method. During installation, first install the first-floor foundation formwork (that is, the precast caisson also serves as the formwork for the cofferdam and the first-floor foundation construction). The first-floor foundation formwork is located in the water, so after the precast caisson is installed as a whole, bottom sealing concrete needs to be poured, and then the water is pumped out.

[0049] S5, High Pile Foundation Casting: Pump out the water from the precast caisson, and cut off the steel casing above 8mm of the base plate (e.g., ...). Figure 11 As shown in the diagram, the vertical reinforcing bars 22 inside the steel casing 2 are exposed. Then, the foundation reinforcement is erected, and the first-floor foundation pouring is carried out. The water depth at the foundation location is relatively large, and there are many piles. The foundation is a high-pile foundation, and the bottom of the foundation is submerged in water for about one meter.

[0050] After the first-layer foundation reaches the required strength, remove the upper hanger 3 and hanger 4, temporarily tie the lower hanger 5 to the first-layer foundation, then complete the reinforcement of the second-layer foundation, install the formwork of the second-layer foundation and pour the foundation.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A deep-water steel pipe pile cofferdam, characterized in that: include, A steel casing is inserted into the bedrock at the bottom of the riverbed. Reinforced concrete piles are then drilled and poured inside the steel casing. Support columns are pre-embedded at the top of the reinforced concrete piles. A suspension system, comprising an upper suspension and a lower suspension, wherein the upper and lower suspensions are connected by a plurality of suspension rods, and the upper suspension is mounted on a support column; A prefabricated caisson includes a base plate, side plates, and corner plates. Several base plates are spliced ​​together and mounted on a lower suspension frame. The base plates are fitted around the outside of the steel casing. Several side plates are spliced ​​together and mounted on the four sides of the lower suspension frame. The corners between the side plates on the four sides are connected by corner plates. The base plate, side plates, and corner plates are spliced ​​together to form a prefabricated caisson with an open top. The lower suspension frame includes a number of first and second crossbeams arranged in a crisscross pattern. The upper sides of the first crossbeams are tightly fixed with second crossbeams, and each pair of second crossbeams forms a group. Both the first and second crossbeams are set in an "I" shape. The side plate has a first bottom beam on its bottom side, and second bottom beams are symmetrically arranged on both sides of the first bottom beam. Both the first bottom beam and the second bottom beam are set in the shape of "I". The second bottom beam is located inside the first bottom beam, and both ends of the second bottom beam extend to the outside of the first bottom beam so that a sliding slot is formed between the two second bottom beams; the corner plate has a mating beam on its bottom side. The side plate along the length of the first crossbeam is supported on the upper end face of the first crossbeam by the first bottom beam, and the side plate along the length of the second crossbeam is supported in the side groove of the second crossbeam by the second bottom beam; the bottom side of the corner plate is supported on the second crossbeam, and the mating beam extends into the sliding slot.

2. The deep-water steel pipe pile cofferdam according to claim 1, characterized in that: The sliding slot of the second bottom beam can be selectively equipped with a slider. Several connecting holes are opened on both sides of the second bottom beam along the length direction. Two first locking rods are internally threaded to the slider. The two first locking rods pass through the connecting holes of the two second bottom beams on the upper side of the first crossbeam respectively, connecting and fixing the two adjacent second bottom beams.

3. The deep-water steel pipe pile cofferdam according to claim 1, characterized in that: The two second crossbeams in each group are set at a fixed distance apart so that an installation groove is formed between the two second crossbeams. A locking block is installed in the installation groove. A guide part is provided in the middle of one side of the locking block. Abutment parts are symmetrically provided on both sides of the guide part. The guide part is installed in the installation groove. The abutment parts abut against the second bottom beam inside the second crossbeam.

4. The deep-water steel pipe pile cofferdam according to claim 3, characterized in that: The two ends of the second crossbeam are respectively provided with first locking holes, and the abutting part and the guide part are respectively provided with second locking holes. The first locking holes and the second locking holes are connected by a second locking rod.

5. The deep-water steel pipe pile cofferdam according to claim 3, characterized in that: The locking block installed on the bottom side of the corner plate has one side abutting part abutting against the mating beam of the corner plate.

6. The deep-water steel pipe pile cofferdam according to claim 5, characterized in that: The mating beam has several through holes, and a positioning pin is fitted in each of the through holes. The positioning pin passes through the connecting hole of the second bottom beam.

7. The deep-water steel pipe pile cofferdam according to claim 1, characterized in that: The side plate has a number of first mounting holes evenly distributed on its upper side and vertical sides, and the corner plate has a number of second mounting holes evenly distributed on its upper side and vertical sides.

8. The deep-water steel pipe pile cofferdam according to claim 1, characterized in that: One side of the base plate has a semi-circular groove for avoiding the steel casing, and the other side of the base plate has a notch for avoiding the lifting rod.

9. The deep-water steel pipe pile cofferdam according to claim 1, characterized in that: The steel casing is provided with several bracket support structures, and the bottom end of the lower hanger is supported on the bracket support structures.

10. A construction method for a deep-water steel pipe pile cofferdam using any one of claims 1-9, characterized in that, The steps are as follows: S1, Install steel casing: Use a floating gantry crane to insert the steel casing into the bedrock at the bottom of the riverbed, ensuring that the top of the steel casing extends above the water surface; S2, Install the drilling platform: Install the drilling platform on the upper side of the steel casing and drill in batches; S3, Pile foundation construction: Cast reinforced concrete piles inside steel casings, and pre-embed support columns at the top of the reinforced concrete piles; remove the drilling platform after the pile foundation construction is completed. S4, Install the hanger system and prefabricated caisson: Install the upper hanger and hanger rod on the support column, then install the lower hanger, adjust the elevation and install the bottom plate, first floor side plate and corner plate, and pour the bottom sealing concrete; S5, High Pile Foundation Casting: The water in the precast caisson is pumped out, the steel casing above the bottom plate is cut off, and then the first-floor foundation construction is carried out.

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