Steel-concrete combined hanging box cofferdam for high-pile bearing platform shaped like Chinese character'wang 'and construction method thereof

Abstract

The invention discloses a steel-concrete combined hanging box cofferdam for a high-pile bearing platform shaped like a Chinese character'wang 'and a construction method of the steel-concrete combined hanging box cofferdam. Comprising a steel casing, a guide ring plate, a steel cable, a bracket, a keel, a prefabricated bottom plate, micro-expansion concrete, a side plate embedded part, a prefabricated side plate, a tension and compression rod embedded part, a tension and compression rod, a first inner support, an inner support stand column, a leakage stopping sandbag, shoulder pole type steel, a hoisting system, a steel strand, local bottom sealing concrete, a shear plate, a bearing platform, a second inner support and a third inner support. The construction process of large-area bottom sealing concrete pouring is omitted, rapid splicing is achieved, and the bearing platform construction efficiency is remarkably improved; meanwhile, the shoulder pole profile steel is used for connecting the prefabricated side plates and the inner supporting stand columns, the length of the steel strands is shortened, and the stability in the lowering process is improved; finally, leakage possibly occurring in the local bottom sealing concrete pouring process is reduced through a guide ring plate, the bottom sealing quality is guaranteed, pollution to the water environment is reduced, and an economical and efficient solution is provided for coastal bridge construction.

Description

Technical Field

[0001] The invention relates to the field of coastal bridge pile foundation engineering construction, and in particular to a steel-concrete combined hanging box cofferdam for a high-pile W-shaped cap and a construction method thereof. Background Art

[0002] With the vigorous development of coastal urban construction, coastal bridges are characterized by a large main tower pedestal area in deep water areas. If conventional steel cofferdams are used for construction, the cofferdam construction is easily affected by the deep water environment, the internal support stability is greatly affected, the bottom pouring of the bottom concrete takes a long time, and the quality is difficult to guarantee. Based on the above reasons, for the high-pile W-shaped pedestal (that is, the pedestal is close to the sea level, so the water pressure on the side wall of the cofferdam is small, and the buoyancy of the bottom plate is also small), combined with the particularity of the cofferdam shape (W-shaped cofferdam), it is necessary to study a steel-concrete composite cofferdam that is easy to construct quickly. Summary of the invention

[0003] The present invention aims to solve the problems in the prior art of high-pile deep-water large-scale construction cost, low efficiency, and difficulty in effectively ensuring the quality of bottom concrete, and provides a steel-concrete composite hanging box cofferdam for a high-pile W-shaped cap and a construction method thereof.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a steel-concrete composite hanging box cofferdam for a high-pile W-shaped cap, comprising a steel casing, a guide ring plate, a steel cable, a corbel, a keel, a prefabricated bottom plate, a slightly expansive concrete, a side plate embedded part, a prefabricated side plate, a tension and compression rod embedded part, a tension and compression rod, a first inner support, an inner support column, a leak-proof sandbag, a shoulder pole steel, a hanging system, a steel strand, a partial bottom sealing concrete, a shear plate, a cap, a second inner support, and a third inner support;

[0005] The corbel is temporarily installed on the outer wall of the steel casing above the design water level, the keel is hoisted on the corbel, several prefabricated bottom plates are installed on the keel, and a post-casting section is reserved between the several prefabricated bottom plates. The micro-expansion concrete is poured in the post-casting section and forms a hanging box bottom plate with the prefabricated bottom plate, and the hanging box bottom plate is in the shape of a lying king;

[0006] A number of side panel embedded parts are embedded in the edge of the hanging box bottom plate, a number of prefabricated side panels are vertically fixed to the edge of the hanging box bottom plate through the side panel embedded parts and spliced ​​to form the hanging box side panels, and the hanging box side panels and the hanging box bottom plate form a steel-concrete composite hanging box;

[0007] A number of tension and compression rod embedded parts are embedded in the bottom plate of the hanging box, and the tension and compression rod embedded parts are evenly arranged around the circumference of the steel casing. The bottom of the tension and compression rod is fixed to the bottom plate of the hanging box through the tension and compression rod embedded parts, and the top of the tension and compression rod is welded and fixed to the outer wall of the steel casing;

[0008] The guide ring plate is temporarily suspended on the steel casing by steel cables and is subsequently fixed to the bottom of the precast floor slab. The leak-proof sandbags are installed inside the guide ring plate, and the partial bottom-sealing concrete is poured inside the guide ring plate;

[0009] The side plates of the lifting box are in the shape of a lying-down king character frame. A pair of first internal supports are installed in the middle of the front and rear inner walls of each rectangular frame of the "king" character frame, and a pair of second internal supports are installed at the front and rear ends of the left and right inner walls. A pair of third internal supports are installed in the middle of the opposite faces of the rectangular frames at both ends of the side plates of the lifting box. The steel casing is located within the rectangular frames separated by the first internal supports, the second internal supports, and the third internal supports. The tops of several internal support columns are respectively fixed to the bottoms at the intersection points of the first internal supports and the third internal supports and the bottom at the position where the first internal support is perpendicular to the center of the steel casing. The bottoms of the internal support columns are fixed to the precast floor slab. One end of the flat steel is welded and fixed to the inner wall of the side plate of the lifting box, and the other end is welded and fixed to the internal support column close to the steel casing;

[0010] The hoisting system is suspended on the steel casing, and the steel strands of the hoisting system are hoisted on the flat steel for hoisting the overall steel-concrete combined lifting box;

[0011] Several shear-resistant plates are embedded in the precast floor slab and are evenly distributed around the circumference of the steel casing. The shear-resistant plates, the tension and compression bar embedded parts, and the internal support columns are arranged alternately. The shear-resistant plates are welded and fixed to the outer wall of the steel casing, and the bearing platform is poured at the bottom inside the steel-concrete combined lifting box.

[0012] Specifically, a fourth internal support is installed in the middle of the opposite faces of the precast side plates between two adjacent rectangular frames of the side plates of the lifting box, and an external support is installed in the middle of the opposite faces of two adjacent rectangular frames of the side plates of the lifting box.

[0013] Specifically, several first strengthening bars are respectively arranged within the rectangular frames separated by the third internal supports and the fourth internal supports, and several second strengthening bars are arranged between two adjacent built-in layer columns.

[0014] Specifically, a sealing gasket is provided between the contact surfaces of the precast side plate and the precast floor slab. A baffle is provided at the top of the side plate embedded part adjacent to the precast side plate, and sealing mortar is poured into the gap between the baffle and the precast side plate.

[0015] A construction method for a steel-concrete combined lifting box cofferdam for a high-pile king-shaped bearing platform includes the following steps:

[0016] S1. After the bored pile construction is completed, the drilling platform is removed, and a guide ring plate is sleeved on the steel casing. The guide ring plate is hoisted on the steel casing by steel cables;

[0017] S2. Drill holes on the side wall of the steel casing above the design water level and install corbels at the holes. Hoist keels on the top of the corbels to form a temporary assembly platform for the bottom plate. Hoist the prefabricated bottom plate on site on the temporary assembly platform for the bottom plate. Reserve post-casting sections between the prefabricated bottom plates. Pour micro-expansion concrete in the post-casting sections. The prefabricated bottom plate and the micro-expansion concrete together form the bottom plate of the hanging box;

[0018] S3, install the prefabricated side panels, install the prefabricated side panels through the side panel embedded parts on the bottom plate of the hanging box, assemble the prefabricated side panels into the hanging box side panels, the hanging box bottom plate and the hanging box side panels form a hanging box, and install the tension and compression rods through the tension and compression rod embedded parts on the bottom plate of the hanging box;

[0019] S4, install the first inner support, the second inner support, the third inner support, and the fourth inner support on the inner side of the hanging box side plate, and weld the inner support column between the first inner support and the prefabricated bottom plate;

[0020] S5. Lift the guide ring plate upwards and weld it to the bottom of the bottom plate of the hanging box, remove the steel cable, and install a leak-proof sandbag in the guide ring plate;

[0021] S6. Weld the pole-shaped steel between the side plate of the hanging box and the inner supporting column, install the hanging system on the steel casing, and then place the steel strand of the hanging system under the pole-shaped steel. The pole-shaped steel serves as a connecting device between the hanging system and the steel-concrete combined hanging box cofferdam. Remove the corbels and keels, and use the hanging system to lift the entire steel-concrete combined hanging box 15 cm.

[0022] S7. Lower the steel-concrete composite hanging box as a whole to the design elevation of the cofferdam, and weld the top of the tension and compression rods to the steel casing when the water level is low before the cofferdam is pumped out;

[0023] S8. Pour local bottom sealing concrete into the guide ring plate. When the local bottom sealing concrete strength reaches the requirement, gradually pump water to the bottom of the steel-concrete composite hanging box, and quickly weld the shear plate buried in the prefabricated bottom plate to the steel casing;

[0024] S9. Remove the tension and compression rods and the hoisting system, cut off the excess steel casing, chisel off the pile head, and start pouring the foundation on the bottom plate of the hanging box to complete the construction of the steel-concrete composite hanging box cofferdam and the entire foundation.

[0025] The beneficial effects of the present invention are:

[0026] In order to optimize the construction process of large-scale high-pile deep-water caps of coastal bridges, the present invention adopts a steel-concrete composite box cofferdam assembled by a prefabricated bottom plate, a prefabricated side plate, an inner support and an inner support column, thereby reducing the construction process of pouring bottom concrete over a large area, realizing rapid assembly, and significantly improving the efficiency of cap construction; at the same time, shoulder-pole steel is used to connect the inner support columns on the prefabricated side plates and the prefabricated bottom plate, thereby enhancing the stability of the inner support of the large cofferdam and shortening the length of the steel strand, thereby increasing the stability of the lowering process; finally, a guide ring plate is used to reduce leakage that may occur during the pouring of local bottom concrete, thereby ensuring the quality of the bottom, reducing pollution to the water environment, and providing an economical and efficient solution for coastal bridge construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a construction schematic diagram of S1 and S2 in the construction method of the present invention;

[0028] Figure 2 It is a construction schematic diagram of S3 in the construction method of the present invention;

[0029] Figure 3 It is a construction schematic diagram of S4, S5 and S6 in the construction method of the present invention;

[0030] Figure 4 It is a schematic diagram of the construction of S8 in the construction method of the present invention;

[0031] Figure 5 It is a schematic diagram of the construction of S9 in the construction method of the present invention;

[0032] Figure 6 It is a schematic diagram of the positions of the first inner support, the second inner support, the third inner support, the fourth inner support, the outer support, and the first reinforcing rod in the cofferdam structure of the present invention;

[0033] Figure 7 for Figure 1 The enlarged schematic diagram of point B in the middle;

[0034] Figure 8 for Figure 2 The enlarged schematic diagram at A in the middle;

[0035] Fig. 9 It is a schematic diagram of the position of the second reinforcing rod in the cofferdam structure of the present invention;

[0036] In the figure: 1 - steel casing; 2 - guide ring plate; 3 - steel cable; 4 - bracket; 5 - keel; 6 - precast bottom plate; 7 - slightly expanded concrete; 8 - side plate embedded part; 9 - precast side plate; 10 - tension and compression bar embedded part; 11 - tension and compression bar; 12 - first internal support; 13 - internal support column; 14 - leak - stopping sandbag; 15 - shoulder - shaped steel; 16 - hoisting system; 17 - steel strand; 18 - partial bottom - sealing concrete; 19 - shear - resistant plate; 20 - bearing platform; 21 - second internal support; 22 - third internal support; 23 - fourth internal support; 24 - external support; 25 - first strengthening bar; 26 - second strengthening bar.

[0037] The following will be described in detail with reference to the accompanying drawings in combination with the embodiments of the present invention. Specific embodiments

[0038] The present invention will be further described below in combination with embodiments:

[0039] As Figure 1-Figure 9 shown, the steel - concrete combined suspension box cofferdam for the high - pile king - shaped bearing platform includes a steel casing 1, a guide ring plate 2, a steel cable 3, a bracket 4, a keel 5, a precast bottom plate 6, slightly expanded concrete 7, a side - plate embedded part 8, a precast side plate 9, a tension and compression bar embedded part 10, a tension and compression bar 11, a first internal support 12, an internal support column 13, a leak - stopping sandbag 14, a shoulder - shaped steel 15, a hoisting system 16, a steel strand 17, partial bottom - sealing concrete 18, a shear - resistant plate 19, a bearing platform 20, a second internal support 21, a third internal support 22, a fourth internal support 23, an external support 24, a first strengthening bar 25, and a second strengthening bar 26.

[0040] The brackets are temporarily installed on the outer wall of the steel casing 1 above the design water level. The keel 5 is hoisted on the brackets 4, and a number of precast bottom plates 6 are installed on the keel 5, and a post - casting section is reserved between the precast bottom plates 6. The slightly expanded concrete 7 is poured into the post - casting section and forms a cofferdam bottom plate with the precast bottom plates 6. The cofferdam bottom plate is in the shape of a lying - down king character.

[0041] A number of side - plate embedded parts 8 are embedded at the edge of the cofferdam bottom plate. A number of precast side plates 9 are vertically fixed to the edge of the cofferdam bottom plate through the side - plate embedded parts 8 and spliced to form a cofferdam side plate. A sealing gasket is provided between the contact surfaces of the precast side plates 9 and the precast bottom plates 6. A baffle adjacent to the precast side plate 9 is provided at the top of the side - plate embedded part 8, and sealing mortar is poured into the gap between the baffle and the precast side plate 9.

[0042] A number of tension and compression bar embedded parts 10 are embedded on the cofferdam bottom plate, and the tension and compression bar embedded parts 10 are evenly distributed around the circumference of the steel casing 1. The bottom of the tension and compression bar 11 is fixed to the cofferdam bottom plate through the tension and compression bar embedded parts 10, and the top of the tension and compression bar 11 is welded and fixed to the outer wall of the steel casing 1.

[0043] The guide ring plate 2 is temporarily suspended on the steel casing 1 by a steel cable 3 and is subsequently fixed to the bottom of the precast floor slab 6. The leak-proof sandbag 14 is installed inside the guide ring plate 2, and the partial bottom-sealing concrete 18 is poured inside the guide ring plate 2.

[0044] The side plates of the suspension box are in the shape of a lying-down king character frame. A pair of first internal supports 12 are installed in the middle of the front and rear inner walls of each rectangular frame of the "king" character frame. A pair of second internal supports 21 are installed at the front and rear ends of the left and right inner walls. A pair of third internal supports 22 are installed in the middle of the opposite faces of the rectangular frames at both ends of the side plates of the suspension box. The steel casing 1 is located within the rectangular frames separated by the first internal supports 12, the second internal supports 21, and the third internal supports 22. The tops of several internal support columns 13 are respectively fixed to the bottoms at the intersection points of the first internal supports 12 and the third internal supports 22 and the bottom at the position where the first internal support 12 is perpendicular to the center of the steel casing 1. The bottoms of the internal support columns 13 are fixed to the precast floor slab 6. The internal support columns 13 are first used to enhance the stability of each internal support. One end of the flat steel 15 is welded and fixed to the inner wall of the side plate of the suspension box, and the other end is welded and fixed to the internal support column 13 near the steel casing 1, which is equivalent to raising the lifting point position of the suspension box, that is, using the internal support column 13 to reduce the length of the steel strand 17. A fourth internal support 23 is installed in the middle of the opposite faces of the precast side plates 9 between two adjacent rectangular frames of the side plates of the suspension box. An external support 24 is installed in the middle of the opposite faces of two adjacent rectangular frames of the side plates of the suspension box. Several first strengthening bars 25 are respectively provided within the rectangular frames separated by the third internal supports 22 and the fourth internal supports 23, and several second strengthening bars 26 are provided between two adjacent internal support columns 13.

[0045] The hoisting system 16 is suspended on the steel casing 1, and the steel strand 17 of the hoisting system 16 is hoisted on the flat steel 15 for hoisting the overall steel-concrete combined suspension box.

[0046] Several shear plates 19 are embedded in the precast floor slab 6 and are evenly distributed around the circumference of the steel casing 1. The shear plates 19, the tension and compression bar embedded parts 10, and the internal support columns 13 are arranged alternately. The shear plates 19 are welded and fixed to the outer wall of the steel casing 1, and the bearing platform 20 is poured at the bottom inside the steel-concrete combined suspension box.

[0047] A construction method for a steel-concrete combined suspension box cofferdam for a high-pile king-shaped bearing platform includes the following steps:

[0048] S1. After the bored pile construction is completed, the bored pile platform is demolished, and the guide ring plate 2 is sleeved on the steel casing 1. The guide ring plate 2 is hoisted on the steel casing 1 by a steel cable 3;

[0049] S2, opening a hole on the side wall of the steel casing 1 above the design water level and installing a corbel 4 at the opening, hoisting a keel 5 on the top of the corbel 4 to form a temporary assembly platform for the bottom plate, hoisting a prefabricated bottom plate 6 on site on the temporary assembly platform for the bottom plate, and reserving a post-casting section between the prefabricated bottom plates 6, pouring micro-expansive concrete 7 in the post-casting section, and the prefabricated bottom plate 6 and the micro-expansive concrete 7 together form the bottom plate of the hanging box;

[0050] S3, install the prefabricated side panels 9, install the prefabricated side panels 9 through the side panel embedded parts 8 on the bottom plate of the hanging box, assemble the prefabricated side panels 9 into the hanging box side panels, the hanging box bottom plate and the hanging box side panels form a hanging box, and install the tension and compression rods 11 through the tension and compression rod embedded parts 10 on the bottom plate of the hanging box;

[0051] S4, install the first inner support 12, the second inner support 21, the third inner support 22, and the fourth inner support 23 on the inner side of the hanging box side plate, and weld the inner support column 13 between the first inner support 12 and the prefabricated bottom plate 6;

[0052] S5, lift the guide ring plate 2 upward and weld it to the bottom of the bottom plate of the hanging box, remove the steel cable 3, and install the leak-proof sandbag 14 in the guide ring plate 2;

[0053] S6, weld the shoulder-pole steel 15 between the side plate of the hanging box and the inner supporting column 13, install the hanging system 16 on the steel casing 1, and then place the steel strand 17 of the hanging system 16 under the shoulder-pole steel 15, the shoulder-pole steel 15 is used as a connecting device between the hanging system 16 and the steel-concrete combined hanging box cofferdam, remove the corbel 4 and the keel 5, and lift the entire steel-concrete combined hanging box 15cm by the hanging system 16;

[0054] S7, lower the steel-concrete composite hanging box as a whole to the design elevation of the cofferdam, and weld the top of the tension and compression rod 11 to the steel casing 1 when the water level is low before the cofferdam is pumped out;

[0055] S8, pouring partial bottom sealing concrete 18 in the guide ring plate 2, and when the strength of the partial bottom sealing concrete 18 reaches the required level, gradually pumping water to the bottom of the steel-concrete composite hanging box, and quickly welding the shear plate 19 buried on the prefabricated bottom plate 6 to the steel casing 1;

[0056] S9, dismantle the tension and compression rods 11 and the hanging system 16, cut off the redundant steel casing 1, chisel off the pile head, and start pouring the cap 20 on the bottom plate of the hanging box, completing the construction of the steel-concrete composite hanging box cofferdam and the entire cap.

[0057] In order to optimize the construction process of high-pile deep-water large-scale foundations of coastal bridges, the present invention adopts a steel-concrete composite box cofferdam assembled by a prefabricated bottom plate 6, a prefabricated side plate 9, internal supports (a first internal support 12, a second internal support 21, a third internal support 22, and a fourth internal support 23) and internal support columns 13, thereby reducing the construction process of pouring bottom concrete over a large area, achieving rapid assembly, and significantly improving the efficiency of foundation construction; at the same time, a shoulder-pole steel 15 is used to connect the prefabricated side plates 9 and the internal support columns 13 on the prefabricated bottom plate 6, shortening the length of the steel strand 17 and increasing the stability of the lowering process; finally, a guide ring plate 2 is used to reduce possible leakage during the pouring of local bottom concrete 18, thereby ensuring the quality of the bottom seal, reducing pollution to the water environment, and providing an economical and efficient solution for coastal bridge construction.

[0058] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] The above is an exemplary description of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or they are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A steel-concrete composite box cofferdam for a high-pile W-shaped cap, characterized in that: It includes a steel casing (1), a guide ring plate (2), a steel cable (3), a bracket (4), a keel (5), a precast bottom plate (6), a slightly expanding concrete (7), a side plate embedded part (8), a precast side plate (9), a tension and compression bar embedded part (10), a tension and compression bar (11), a first internal support (12), an internal support column (13), a leakage-proof sandbag (14), a flat steel (15), a hoisting system (16), a steel strand (17), a partial bottom-sealing concrete (18), a shear-resistant plate (19), a bearing platform (20), a second internal support (21), and a third internal support (22); The bracket is temporarily installed on the outer wall of the steel casing (1) above the designed water level. The keel (5) is hoisted on the bracket (4). A number of precast bottom plates (6) are installed on the keel (5), and a post-cast section is reserved between the precast bottom plates (6). The slightly expanding concrete (7) is poured into the post-cast section and forms a caisson bottom plate with the precast bottom plate (6). The caisson bottom plate is in an inverted "W" shape; A number of side plate embedded parts (8) are embedded at the edge of the caisson bottom plate. A number of precast side plates (9) are vertically fixed to the edge of the caisson bottom plate through the side plate embedded parts (8) and are spliced to form caisson side plates. The caisson side plates and the caisson bottom plate form a steel-concrete combined caisson; A number of tension and compression bar embedded parts (10) are embedded on the caisson bottom plate, and the tension and compression bar embedded parts (10) are evenly distributed around the circumference of the steel casing (1). The bottom of the tension and compression bar (11) is fixed to the caisson bottom plate through the tension and compression bar embedded parts (10), and the top of the tension and compression bar (11) is welded and fixed to the outer wall of the steel casing (1); The guide ring plate (2) is temporarily hung on the steel casing (1) through the steel cable (3) and is subsequently fixed to the bottom of the precast bottom plate (6). The leakage-proof sandbag (14) is installed inside the guide ring plate (2), and the partial bottom-sealing concrete (18) is poured inside the guide ring plate (2); The caisson side plates are in an inverted "W" shaped frame. A pair of first internal supports (12) are installed in the middle of the front and rear inner walls of each rectangular frame of the "W" shaped frame. A pair of second internal supports (21) are installed at the front and rear ends of the left and right inner walls. A pair of third internal supports (22) are installed in the middle of the opposite faces of the rectangular frames at both ends of the caisson side plates. The steel casing (1) is located inside the rectangular frames separated by the first internal supports (12), the second internal supports (21), and the third internal supports (22). The tops of a number of internal support columns (13) are respectively fixed to the bottoms at the intersection points of the first internal supports (12) and the third internal supports (22) and the bottom at the position where the first internal support (12) is perpendicular to the center of the steel casing (1). The bottoms of the internal support columns (13) are fixed to the precast bottom plate (6). One end of the flat steel (15) is welded and fixed to the inner wall of the caisson side plate, and the other end is welded and fixed to the internal support column (13) close to the steel casing (1); The hoisting system (16) is suspended on the steel casing (1), and the steel strands (17) of the hoisting system (16) are hoisted on the flat steel (15) for hoisting the overall steel-concrete combined caisson; A plurality of shear plates (19) are embedded in the prefabricated bottom plate (6), and the shear plates (19) are evenly distributed around the circumference of the steel casing (1). The shear plates (19), the tension and compression rod embedded parts (10) and the inner support columns (13) are staggered. The shear plates (19) are welded and fixed to the outer wall of the steel casing (1), and the cap (20) is cast at the bottom of the steel-concrete composite hanging box.

2. The steel-concrete composite hanging box cofferdam for high pile W-shaped cap according to claim 1 is characterized in that: A fourth inner support (23) is installed at the middle of the opposite surfaces of the prefabricated side plate (9) between two adjacent rectangular frames of the hanging box side plate, and an outer support (24) is installed at the middle of the opposite surfaces of the two adjacent rectangular frames of the hanging box side plate.

3. The steel-concrete composite hanging box cofferdam for high pile W-shaped cap according to claim 2 is characterized in that: A plurality of first reinforcing rods (25) are respectively arranged in the rectangular frames separated by the third inner support (22) and the fourth inner support (23), and a plurality of second reinforcing rods (26) are arranged between two adjacent inner layer columns (13).

4. The steel-concrete composite hanging box cofferdam for high pile W-shaped cap according to claim 3 is characterized in that: A sealing pad is provided between the contact surfaces of the prefabricated side plate (9) and the prefabricated bottom plate (6), a baffle plate close to the prefabricated side plate (9) is provided on the top of the side plate embedded part (8), and sealing mortar is poured in the gap between the baffle plate and the prefabricated side plate (9).

5. A construction method for a steel-concrete composite hanging box cofferdam for a high-pile W-shaped cap according to claim 4, characterized in that: The following steps are involved: S1. After the bored pile construction is completed, the drilling platform is removed, and a guide ring plate (2) is installed on the steel casing (1). The guide ring plate (2) is hoisted on the steel casing (1) through a steel cable (3); S2, drilling a hole on the side wall of the steel casing (1) above the design water level and installing a corbel (4) at the hole, hoisting a keel (5) on the top of the corbel (4) to form a temporary assembly platform for the bottom plate, hoisting a prefabricated bottom plate (6) on site on the temporary assembly platform for the bottom plate, reserving a post-casting section between the prefabricated bottom plates (6), pouring micro-expansive concrete (7) in the post-casting section, and the prefabricated bottom plate (6) and the micro-expansive concrete (7) together forming the bottom plate of the hanging box; S3, installing the prefabricated side panels (9), installing the prefabricated side panels (9) through the side panel embedded parts (8) on the bottom plate of the hanging box, assembling the prefabricated side panels (9) into the hanging box side panels, the hanging box bottom plate and the hanging box side panels form a hanging box, and installing the tension and compression rods (11) through the tension and compression rod embedded parts (10) on the bottom plate of the hanging box; S4, installing a first inner support (12), a second inner support (21), a third inner support (22), and a fourth inner support (23) on the inner side of the hanging box side plate, and welding an inner support column (13) between the first inner support (12) and the prefabricated bottom plate (6); S5, lift the guide ring plate (2) upwards and weld it to the bottom of the bottom plate of the hanging box, remove the steel cable (3), and install the leak-proof sandbag (14) in the guide ring plate (2); S6, welding a shoulder-pole steel (15) between the side plate of the hanging box and the inner supporting column (13), installing a hanging system (16) on the steel casing (1), and then placing the steel strand (17) of the hanging system (16) under the shoulder-pole steel (15), the shoulder-pole steel (15) serving as a connecting device between the hanging system (16) and the steel-concrete combined hanging box cofferdam, removing the corbels (4) and the keel (5), and hoisting the entire steel-concrete combined hanging box 15 cm by the hanging system (16); S7, lowering the steel-concrete composite hanging box as a whole to the design elevation of the cofferdam, and welding the top of the tension and compression rod (11) to the steel casing (1) when the water level is low before the cofferdam is pumped out; S8, pouring partial bottom sealing concrete (18) into the guide ring plate (2), and after the strength of the partial bottom sealing concrete (18) reaches the required level, gradually pumping water to the bottom of the steel-concrete composite hanging box, and quickly welding the shear plate (19) buried on the prefabricated bottom plate (6) to the steel casing (1); S9, dismantle the tension and compression rods (11) and the hanging system (16), cut off the redundant steel casing (1), chisel off the pile head, and start pouring the cap (20) on the bottom plate of the hanging box, completing the construction of the steel-concrete composite hanging box cofferdam and the entire cap.

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