Construction method of large cantilever winged steel box girder

Abstract

The present application relates to a kind of cantilever winged steel box girder hoisting construction method, comprising the following specific steps: step one, construction preparation;Step two, steel pipe pile and side pier construction;Step three, temporary support construction;Step four, steel box girder hoisting installation;Step five, cantilever steel box girder hoisting installation;Step six, steel box girder linear adjustment;Step seven, steel-mixing combination section top hoisting steel box prestressed tension construction;Step eight, temporary support and steel pipe pile dismantling construction;Step nine, construction is completed and checks acceptance, equipment and machinery dismantling and leaving the scene.The present application belongs to the field of bridge engineering construction, not only can improve the stability of temporary support structure, steel box girder installation precision, side pier top adjustment precision and convenience, cantilever installation speed, prestressed tension effect, improve construction quality at the same time, greatly improve the efficiency of steel box girder hoisting and installation construction on site, save manpower and cost, applied in practical engineering can obtain good technical and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering and is applicable to the construction of steel box girder hoisting, especially to the construction of large cantilevered winged steel box girder hoisting. Background Technology

[0002] Currently, in order to maximize the span while reducing the bridge's self-weight and increasing its load-bearing capacity, the main beams of long-span suspension bridges in China are generally made of steel box girder structures. Steel box girders are usually processed in factories and assembled on-site, which greatly reduces the construction time of the bridge on the river surface. They also have advantages such as large span, novel structure, and simple and beautiful appearance, and are widely used in bridge engineering. After the steel box girders are transported to the construction site, they need to be hoisted and installed. In order to ensure the construction quality and progress of the steel box girder construction, it is particularly important to complete the hoisting and installation quickly. Among them, how to ensure construction efficiency and installation accuracy for the cantilever section of the large cantilevered steel box girder has become a construction challenge. In the past, the construction efficiency was low and the labor cost was high.

[0003] In view of this, and in light of the shortcomings of previous steel box girder hoisting construction, there is an urgent need for a new construction method for a large cantilever winged steel box girder hoisting system to improve construction efficiency, enhance construction quality, and ensure safe and reliable construction quality. Summary of the Invention

[0004] The purpose of this invention is to provide a method for hoisting and installing large cantilevered steel box girders that can effectively improve the stability of temporary support structures, the installation accuracy of steel box girders, the adjustment accuracy and convenience of side pier tops, the installation speed of cantilever arms, and the prestressing tensioning effect. At the same time, it improves construction quality, greatly increases the efficiency of on-site steel box girder hoisting and installation, saves manpower and costs, and has the characteristics of being environmentally friendly and energy-saving, convenient to construct, and simple to operate.

[0005] To achieve the above-mentioned technology, the present invention adopts the following technical solution:

[0006] A method for hoisting and constructing a large cantilevered steel box girder includes the following steps:

[0007] Step 1, Construction Preparation: Implement on-site traffic control, close off the construction area, allow machinery and equipment to enter the site, and inspect and accept the construction materials entering the site;

[0008] Step 2, Construction of steel pipe piles and side piers: First, construct the steel pipe piles, and then construct the side piers at the top of the steel pipe piles; after the side piers are constructed, arrange the pier top; fix the hydraulic jacks on the side piers, set the top plate on top of the hydraulic jacks, and fix the support beams on the top plate.

[0009] Step three, temporary support construction: embedded parts are arranged in the enlarged foundation, the column is fixed on the enlarged foundation through the embedded parts, the adjacent two columns are connected through the support steel, and the enlarged end plate is arranged at the top of the column;

[0010] Step four, steel box girder hoisting installation: combined construction of automobile crane and gantry crane, the gantry crane track is fixed on the ground, the gantry crane is arranged on the gantry crane track, the hoisting rope is arranged on the gantry crane, the lifting lug is arranged on the steel box girder, the groove base is arranged on the steel pipe pile and the temporary support, and the groove base is arranged on both sides of the steel box girder installation position; the steel sheet is arranged on the groove base; a plurality of hydraulic jacks are fixed on the steel sheet, and the steel box girder is adjusted in the horizontal position during hoisting through the hydraulic jacks on the steel sheet;

[0011] Step five, hoisting installation of cantilever steel box girder: first, assemble the steel box girder large cantilever cantilever installation fixed support, after the assembly of the steel box girder large cantilever cantilever installation fixed support is completed, the cantilever steel box girder is hoisted and placed on the inclined support plate; the installation of the cantilever steel box girder is completed through the steel box girder large cantilever cantilever installation fixed support;

[0012] Step six, linear adjustment of steel box girder: the rectangular frame base is placed at the lower end of the steel box girder, the rectangular frame base is fixed through the U-shaped hoop and the fixing nail, the hydraulic jack is arranged on the rectangular frame base through the fixed circular sleeve, and the height of the steel box girder is adjusted through the hydraulic jack on the rectangular frame base;

[0013] Step seven, steel box internal prestressed tensioning construction of the top of the steel-concrete combined section: the frame body is fixed and installed at the top of the steel box girder, the fixed steel pipe is arranged at the top of the frame body, the adjustable hanging rope is arranged on the fixed steel pipe, the lifting hook is arranged at the lower end of the adjustable hanging rope, the tensioning equipment is connected with the lifting hook, and then the steel box girder is prestressed and tensioned through the tensioning equipment;

[0014] Step eight, temporary support and steel pipe pile demolition construction: after the steel box girder is welded and the welding seam is qualified, the stay cable is tensioned; after the stay cable tensioning is completed, the temporary support does not bear the load of the steel box girder, and then the temporary support is removed;

[0015] Step nine, construction is completed and inspection and acceptance, equipment and machinery are removed and leave the scene.

[0016] As preferred, in step three, the upper and lower two columns are fixed through connecting bolts, and the welded fixing parts are arranged on the enlarged end plate.

[0017] As preferred, in step four, the groove base is provided with a groove, and the lower end of the steel sheet is fixed in the groove.

[0018] As preferred, in step five, the assembly method of the steel box girder large cantilever cantilever installation fixed support is as follows:

[0019] The movable track is arranged on the temporary support, the roller is arranged at the bottom of the main profile steel frame, the transverse profile steel bottom frame and the transverse positioning rod are fixed on the main profile steel frame, one end of the oblique support plate is fixed on the main profile steel frame, and the other end is fixed on the transverse profile steel bottom frame, one end of the vertical positioning rod is fixed on the transverse positioning rod, and the other end is fixed on the transverse profile steel bottom frame; the extendable baffle is arranged at one end of the transverse profile steel bottom frame away from the main profile steel frame through a hinge; after the main profile steel frame is adjusted to the installation position, one end of the support fixing rod is fixed on the transverse profile steel bottom frame, and the other end is fixed on the temporary support; and the main profile steel connecting rod is fixedly connected with two adjacent main profile steel frames.

[0020] After the steel box girder large cantilever cantilever installation fixing support is assembled, the cantilever steel box girder is hoisted and placed on the oblique support plate; and the installation of the cantilever steel box girder is completed through the extension of the extendable baffle.

[0021] As preferred, in the assembling of the steel box girder large cantilever cantilever installation fixing support, one end of the inner support rod and the support short rod is fixed on the oblique support plate, and the other end is fixed on the transverse profile steel bottom frame.

[0022] As preferred, in step seven, the frame body is built by the transverse support steel pipe and the vertical support steel pipe.

[0023] As preferred, in step five, when the cantilever steel box girder is installed, the extendable baffle is erected, the cantilever steel box girder is placed on the oblique support plate, the cantilever steel box girder is positionally constrained through the extendable baffle to prevent it from falling; when the cantilever steel box girder is adjusted to the installation position, the extendable baffle is laid flat, the constraint on the extendable baffle is released, the cantilever steel box girder is moved to the installation position and installed.

[0024] The present application has the following characteristics and beneficial effects:

[0025] (1) The temporary support system can be quickly assembled to meet the height requirements of the bridge, and the materials can be reused, thereby greatly reducing the material and transportation costs.

[0026] (2) Through the overall adjustable pad on the side pier top, the gantry crane hoisting adjustment system, the steel box girder installation elevation adjustment technology, the horizontal and vertical positions of the steel box girder can be quickly and accurately adjusted, the operation is simple, the manpower is saved, the traditional method of using a pull hook to adjust is avoided, and the construction efficiency is improved.

[0027] (3) The steel box girder large cantilever cantilever installation fixing support is used for the hoisting construction of the cantilever steel box girder, the positioning and installation speed and precision of the cantilever steel box girder are improved, the manpower is saved, and the construction progress is accelerated.

[0028] (4) The steel box is hung at the top of the steel-concrete combined section by the prestress tension technology, the precision of the tension position at the same height can be precisely controlled, only one person is needed for construction, the labor input is reduced, the construction efficiency is improved, and the cost is saved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a front view of a temporary support structure;

[0030] Figure 2 is a side view of a temporary support structure;

[0031] Figure 3 is a schematic view of an adjustable pad structure on the top of a side pier;

[0032] Figure 4 is a schematic view of a gantry crane hoisting adjustment system structure;

[0033] Figure 5 is a schematic view of a hydraulic jack installation structure of a gantry crane hoisting adjustment system;

[0034] Figure 6 is a schematic view of a steel box girder installation elevation adjustment device structure;

[0035] Figure 7 is a front view of a steel box girder large cantilever cantilever installation fixed support structure;

[0036] Figure 8 is a side view of a steel box girder large cantilever cantilever installation fixed support structure;

[0037] Figure 9 is a schematic view of a prestress tension device structure in a steel box hung at the top of a steel-concrete combined section;

[0038] Figure 10 is Figure 9 A-A sectional view in the middle;

[0039] In the diagram: 1-Enlarged foundation, 2-Embedded parts, 3-Column, 4-Column connecting bolts, 5-Supporting steel, 6-Enlarged end plate, 7-Welded fasteners, 8-Side pier, 9-Hydraulic jack, 10-Top plate, 11-Supporting beam, 12-Steel pipe pile, 13-Gantry crane track, 14-Temporary support, 15-Gantry crane, 16-Lifting rope, 17-Lifting lug, 18-Steel box girder, 19-Thin steel plate, 20-Groove base, 21-Groove, 22-Rectangular frame base, 23-Fixing nail, 24-Fixing circular clamp, 25-U-shaped clamp. 26-Moving track, 27-Roller, 28-Horizontal steel base frame, 29-Inner support rod, 30-Short support rod, 31-Diagonal support plate, 32-Horizontal limiting rod, 33-Main steel frame, 34-Horizontal positioning rod, 35-Vertical positioning rod, 36-Cantilever steel box girder, 37-Extendable baffle, 38-Hinge, 39-Support fixing rod, 40-Main steel frame connecting rod, 41-Concrete box girder, 42-Horizontal support steel pipe, 43-Vertical support steel pipe, 44-Fixed steel pipe, 45-Adjustable hanging rope, 46-Hook, 47-Tensioning equipment. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the description is not limited to the following embodiments.

[0041] Figure 1 This is a front view of the temporary support structure. Figure 2 This is a side view of the temporary support structure. Figure 3 This is a schematic diagram of the adjustable support structure on the top of the pier. Figure 4 This is a schematic diagram of the gantry crane hoisting and adjustment system structure. Figure 5 This is a schematic diagram of the hydraulic jack installation structure for the gantry crane hoisting and adjustment system. Figure 6 This is a schematic diagram of the elevation adjustment device for steel box girder installation. Figure 7 This is a front view of the steel box girder cantilever arm installation and fixing support structure. Figure 8 This is a side view of the steel box girder cantilever arm installation and fixing support structure. Figure 9 This is a schematic diagram of the prestressing tensioning technology within the steel box suspended at the top of the steel-concrete composite section. Figure 10 yes Figure 9 AA section view, see details. Figures 1 to 10 .

[0042] like Figures 1 to 10 As shown, the large cantilevered steel box girder hoisting system includes temporary support 14, adjustable pads on the top of the side piers, gantry crane hoisting and adjustment system, steel box girder installation elevation adjustment device, large cantilevered steel box girder installation and fixing support, and prestressing tensioning device for the steel box girder suspended at the top of the steel-concrete composite section.

[0043] The temporary support 14 comprises an enlarged foundation 1, a pre-embedded part 2, a column 3, a column connecting bolt 4, a support profile steel 5, an enlarged end plate 6, a welding fixing part 7, the pre-embedded part 2 is arranged in the enlarged foundation 1, the column 3 is fixed on the enlarged foundation 1 through the pre-embedded part 2, the support profile steel 5 is arranged between the two columns 3, the column connecting bolt 4 is used for fixing the upper and lower two columns 3, the enlarged end plate 6 is arranged at the top of the column 3, and the welding fixing part 7 is arranged on the enlarged end plate 6. The enlarged end plate 6 is used for expanding the bearing area of the top of the column 3, and the welding fixing part 7 is used for welding and fixing with other parts.

[0044] As an improved embodiment, the whole pier top adjustable cushion of the side pier further comprises a side pier 8, a hydraulic jack 9, a top plate 10, a support cross beam 11 and a steel pipe pile 12, the side pier 8 is arranged at the top end of the steel pipe pile 12, the hydraulic jack 9 is fixed on the side pier 8, the hydraulic jack 9 on the side pier 8 is vertically arranged, and the top plate 10 is arranged at the top of the hydraulic jack 9; the support cross beam 11 is correspondingly arranged around the bottom of the steel box girder 18 and is fixed on the top plate 10.

[0045] As an improved embodiment, the gantry crane hoisting adjustment system further comprises a hydraulic jack 9, a gantry crane track 13, a temporary support 14, a gantry crane 15, a hoisting rope 16, a lifting lug 17, a steel box girder 18, a profile steel sheet 19 and a grooved base 20, the gantry crane track 13 is fixed on the ground, the gantry crane 15 is arranged on the gantry crane track 13, the hoisting rope 16 is arranged on the gantry crane 15, the lifting lug 17 is arranged on the upper end of the steel box girder 18, the grooved base 20 is arranged on the steel pipe pile 12 and the temporary support 14, and the grooved base 20 is located on both sides of the installation position of the steel box girder 18; the grooved base 20 is provided with a groove 21, the profile steel sheet 19 is arranged on the grooved base 20, the lower end of the profile steel sheet 19 is fixed in the groove 21, and a plurality of hydraulic jacks 9 are fixed on the profile steel sheet 19, and the hydraulic jacks 9 arranged on the profile steel sheet 19 are horizontally arranged.

[0046] As an improved embodiment, the steel box girder installation elevation adjustment device further comprises a hydraulic jack 9, a rectangular frame base 22, a fixing nail 23, a fixing circular sleeve 24 and a U-shaped clamp 25, the rectangular frame base 22 is arranged at the lower end of the steel box girder 18, the rectangular frame base 22 is fixed through the U-shaped clamp 25 and the fixing nail 23, the hydraulic jack 9 is arranged on the rectangular frame base 22 through the fixing circular sleeve 24, and the hydraulic jack 9 is located at the four corners of the inner side of the rectangular frame base 22. When the steel box girder is hoisted, the installation height of the steel box girder 18 is adjusted through the hydraulic jack 9 arranged on the rectangular frame base 22 at the lower end of the steel box girder 18.

[0047] As an improved specific embodiment, the steel box girder large cantilever cantilever installation fixing support further comprises a movable track 26, a roller 27, a transverse steel bottom frame 28, an inner support rod 29, a support short rod 30, an inclined support plate 31, a transverse limiting rod 32, a main steel frame 33, a transverse positioning rod 34, a vertical positioning rod 35, a cantilever steel box girder 36, an extendable baffle 37, a hinge 38, a support fixing rod 39, and a main steel frame connecting rod 40. The movable track 26 is arranged on the temporary support 14, the roller 27 is arranged at the bottom of the main steel frame 33, and the roller 27 is located on the movable track 26 and can move along the movable track. The main steel frame 33 is arranged vertically, the transverse steel bottom frame 28 and the transverse positioning rod 34 are fixed on the main steel frame 33, one end of the inclined support plate 31 is fixed on the main steel frame 33, and the other end is fixed on the transverse steel bottom frame 28. One end of the inner support rod 29 and the support short rod 30 is fixed on the inclined support plate 31, and the other end of the inner support rod 29 and the support short rod 30 is fixed on the transverse steel bottom frame 28. One end of the vertical positioning rod 35 is fixed on the transverse positioning rod 34, and the other end is fixed on the transverse steel bottom frame 28. The extendable baffle 37 is arranged at the end of the transverse steel bottom frame 28 away from the main steel frame 33 through the hinge 38, and the extendable baffle 37 can be turned over through the hinge 38. One end of the support fixing rod 39 is fixed on the transverse steel bottom frame 28, and the other end is fixed on the temporary support 14. The main steel frame connecting rod 40 is connected between two adjacent main steel frames 33, and is used for fixedly connecting the two adjacent main steel frames 33.

[0048] As an improved specific embodiment, the steel box girder large cantilever cantilever installation fixing support further comprises a movable track 26, a roller 27, a transverse steel bottom frame 28, an inner support rod 29, a support short rod 30, an inclined support plate 31, a transverse limiting rod 32, a main steel frame 33, a transverse positioning rod 34, a vertical positioning rod 35, a cantilever steel box girder 36, an extendable baffle 37, a hinge 38, a support fixing rod 39, and a main steel frame connecting rod 40. The movable track 26 is arranged on the temporary support 14, the roller 27 is arranged at the bottom of the main steel frame 33, and the roller 27 is located on the movable track 26 and can move along the movable track. The main steel frame 33 is arranged vertically, the transverse steel bottom frame 28 and the transverse positioning rod 34 are fixed on the main steel frame 33, one end of the inclined support plate 31 is fixed on the main steel frame 33, and the other end is fixed on the transverse steel bottom frame 28. One end of the inner support rod 29 and the support short rod 30 is fixed on the inclined support plate 31, and the other end of the inner support rod 29 and the support short rod 30 is fixed on the transverse steel bottom frame 28. One end of the vertical positioning rod 35 is fixed on the transverse positioning rod 34, and the other end is fixed on the transverse steel bottom frame 28. The extendable baffle 37 is arranged at the end of the transverse steel bottom frame 28 away from the main steel frame 33 through the hinge 38, and the extendable baffle 37 can be turned over through the hinge 38. One end of the support fixing rod 39 is fixed on the transverse steel bottom frame 28, and the other end is fixed on the temporary support 14. The main steel frame connecting rod 40 is connected between two adjacent main steel frames 33, and is used for fixedly connecting the two adjacent main steel frames 33.

[0049] The large cantilever spread-wing steel box girder hoisting construction method comprises the following steps:

[0050] Step one, construction preparation: good on-site traffic control, close the construction area, mechanical equipment into the field, the construction materials entering the site are inspected and accepted.

[0051] Step two, steel pipe pile and side pier construction: first, construct steel pipe pile 12, then construct side pier 8 on the upper end of steel pipe pile 12; after side pier 8 construction is completed, perform pier top arrangement; fix hydraulic jack 9 on side pier 8, set top plate 10 on the top of hydraulic jack 9, correspondingly arrange support cross beam 11 on the bottom of steel box girder 18, and fix support cross beam 11 on top plate 10.

[0052] Step three, temporary support 14 construction: embed part 2 in enlarged foundation 1, fix column 3 on enlarged foundation 1 through embed part 2, connect two adjacent columns 3 through support section steel 4, and fix two columns 3 through connecting bolt 4; set enlarged end plate 6 on the top of column 3, and set welded fixing part 7 on enlarged end plate 6.

[0053] Step four, steel box girder hoisting and installation: adopt combined construction of automobile crane and gantry crane, fix gantry crane track 13 on the ground, set gantry crane 15 on gantry crane track 13, set hoisting rope 16 on gantry crane 15, set lifting lug 17 on steel box girder 18, set recessed base 20 on steel pipe pile 12 and temporary support 14, and set recessed base 20 on both sides of the installation position of steel box girder 18; install section steel sheet 19 on recessed base 20; recess 21 is arranged on recessed base 20, and the lower end of section steel sheet 19 is fixed in recess 21; multiple hydraulic jacks 9 are fixed on section steel sheet 19; steel box girder enters the area between two section steel sheets 19 in the hoisting process, and the horizontal position of steel box girder 18 in the hoisting process is finely adjusted through hydraulic jacks 9 on section steel sheet 19.

[0054] Step five, hoisting and installation of cantilever steel box girder 36: first, assemble steel box girder large cantilever installation fixing support, and the assembly method is as follows:

[0055] Set movable track 26 on temporary support 14, set roller 27 on the bottom of main section steel frame 33, fix horizontal section steel bottom frame 28 and horizontal positioning rod 34 on main section steel frame 33, fix one end of inclined support plate 31 on main section steel frame 33 and the other end on horizontal section steel bottom frame 28, fix one end of inner support rod 29 and support short rod 30 on inclined support plate 31 and the other end on horizontal section steel bottom frame 28; fix one end of vertical positioning rod 35 on horizontal positioning rod 34 and the other end on horizontal section steel bottom frame 28; set extendable baffle 37 on the end of horizontal section steel bottom frame 28 away from main section steel frame 33 through hinge 38; after main section steel frame 33 is adjusted to the installation position, fix one end of support fixing rod 39 on horizontal section steel bottom frame 28 and the other end on temporary support 14, and fix main section steel connecting rod 40 on two adjacent main section steel frames 33;

[0056] After the completion of the assembly of the steel box girder large cantilever cantilever installation fixing support, the cantilever steel box girder 36 is hoisted and placed on the inclined support plate 31; the installation of the cantilever steel box girder is completed through the extension of the extendable baffle. The specific method is as follows: the extendable baffle is erected, and the cantilever steel box girder 36 is placed on the inclined support plate 31; the position of the cantilever steel box girder 36 is constrained by the extendable baffle 37 to prevent it from falling; when the cantilever steel box girder 36 is adjusted to the installation position, the extendable baffle 37 is placed flat, the constraint of the extendable baffle 37 is released, and the cantilever steel box girder 36 is moved to the installation position and installed.

[0057] Step six, linear adjustment of steel box girder: the steel box girder installation elevation adjustment device is used, the rectangular frame base 22 is placed at the lower end of the steel box girder 18, and the rectangular frame base 22 is fixed by the U-shaped hoop 25 and the fixing nail 23; the hydraulic jack 9 is installed on the rectangular frame base 22, the hydraulic jack is vertically arranged, the hydraulic jack 9 is arranged on the rectangular frame base 22 through the fixed circular sleeve hoop 24, and the elevation of the steel box girder 18 is adjusted by the hydraulic jack 9 on the rectangular frame base 22, and the steel box girder 18 is adjusted horizontally by the hydraulic jack 9 on the thin plate 19 of the shaped steel.

[0058] Step seven, steel box inner prestressed tensioning construction of steel box girder top hanging: the frame body is fixedly installed at the top of the steel box girder 18, the frame body is built by the horizontal support steel pipe 42 and the vertical support steel pipe 43, the fixed steel pipe 44 is arranged at the top of the frame body, the adjustable hanging rope 45 is arranged on the fixed steel pipe 44, the lifting hook 46 is arranged at the lower end of the adjustable hanging rope 45, the tensioning equipment 47 is connected with the lifting hook 46, and then the steel box girder 18 is prestressed and tensioned by the tensioning equipment 47.

[0059] Step eight, temporary support 14 and steel pipe pile demolition construction: after the welding of the steel box girder 18 is completed and the welding seam is qualified, the cable-stayed cable is tensioned; after the cable-stayed cable tensioning is completed, the temporary support 14 does not bear the load of the steel box girder 18, and then the temporary support 14 is removed.

[0060] Step nine, construction is completed and inspection and acceptance, equipment and machinery are removed and leave the scene.

Claims

1. A method for hoisting and constructing a large cantilevered steel box girder, characterized in that: Includes the following steps: Step 1, Construction Preparation: Implement on-site traffic control, close off the construction area, allow machinery and equipment to enter the site, and inspect and accept the construction materials entering the site; Step 2, Construction of steel pipe piles and side piers: First, construct steel pipe piles (12), and then construct side piers (8) at the upper end of steel pipe piles (12); after the side piers (8) are constructed, arrange the top of the piers; fix the hydraulic jacks (9) on the side piers (8), set the top plate (10) on the top of the hydraulic jacks (9), and fix the supporting beams (11) on the top plate (10); Step 3, temporary support (14) construction: the embedded part (2) is set in the enlarged foundation (1), the column (3) is fixed on the enlarged foundation (1) through the embedded part (2), the two adjacent columns (3) are connected by the supporting steel (5), and the enlarged end plate (6) is set on the top of the column (3); Step 4, Steel Box Girder Lifting and Installation: A combination of truck crane and gantry crane is used for construction. The gantry crane track (13) is fixed to the ground, the gantry crane (15) is erected on the gantry crane track (13), the lifting rope (16) is set on the gantry crane (15), the lifting lug (17) is set on the steel box girder (18), and the grooved base (20) is set on the steel pipe pile (12) and the temporary support (14). The grooved base (20) is located on both sides of the installation position of the steel box girder (18); the steel sheet (19) is installed on the grooved base (20); multiple hydraulic jacks (9) are fixed on the steel sheet (19), and the lateral position of the steel box girder (18) is finely adjusted during the lifting process by the hydraulic jacks (9) on the steel sheet (19); Step 5, hoisting and installing the cantilever steel box girder (36): First, assemble the cantilever steel box girder installation and fixing bracket. After the cantilever steel box girder installation and fixing bracket is assembled, hoist the cantilever steel box girder (36) and place it on the inclined support plate (31); complete the installation of the cantilever steel box girder (36) through the cantilever steel box girder installation and fixing bracket. The assembly method for the installation and fixing bracket of the large cantilever arm of the steel box girder is as follows: Set the moving track (26) on the temporary support (14), set the rollers (27) at the bottom of the main steel frame (33), fix the transverse steel base frame (28) and the transverse positioning rod (34) on the main steel frame (33), fix one end of the diagonal support plate (31) on the main steel frame (33) and the other end on the transverse steel base frame (28), fix one end of the vertical positioning rod (35) on the transverse positioning rod (34), and the other end on the other end on the transverse steel base frame (28). The end is fixed on the transverse steel base frame (28); the extendable baffle (37) is set at the end of the transverse steel base frame (28) away from the main steel frame (33) by a hinge (38); after the main steel frame (33) is adjusted to the installation position, one end of the support fixing rod (39) is fixed on the transverse steel base frame (28), and the other end is fixed on the temporary support (14); the main steel connecting rod (40) is fixedly connected to two adjacent main steel frames (33); After the steel box girder cantilever arm installation and fixing bracket is assembled, the cantilever steel box girder (36) is hoisted and placed on the inclined support plate (31); the installation of the cantilever steel box girder (36) is completed by extending the extendable baffle (37); Step 6, Linear adjustment of steel box girder: Place the rectangular frame base (22) at the lower end of the steel box girder (18), fix the rectangular frame base (22) with U-shaped clamps (25) and fixing nails (23), and set the hydraulic jack (9) on the rectangular frame base (22) with fixing circular sleeves (24). Adjust the elevation of the steel box girder (18) by using the hydraulic jack (9) on the rectangular frame base (22); Step 7, Prestressing tensioning construction of the steel box girder (18) suspended at the top: A frame is fixedly installed at the top of the steel box girder (18), a fixed steel pipe (44) is set at the top of the frame, an adjustable hanging rope (45) is set on the fixed steel pipe (44), a hook (46) is set at the lower end of the adjustable hanging rope (45), a tensioning device (47) is connected to the hook (46), and then the steel box girder (18) is prestressed through the tensioning device (47); Step 8, temporary support (14) and steel pipe pile removal construction: After the steel box girder (18) is welded and the weld seam passes the non-destructive testing, the stay cables are tensioned; after the stay cables are tensioned and the temporary support (14) no longer bears the load of the steel box girder (18), the temporary support (14) is removed. Step nine: After construction is completed and inspected, the equipment and machinery are dismantled and removed from the site.

2. The method for hoisting and constructing a large cantilevered steel box girder according to claim 1, characterized in that, In step three, the upper and lower columns (3) are fixed together by connecting bolts (4), and welding fasteners (7) are installed on the enlarged end plate (6).

3. The method for hoisting and constructing a large cantilevered steel box girder according to claim 1, characterized in that, In step four, a groove (21) is provided on the grooved base (20), and the lower end of the steel sheet (19) is fixed in the groove (21).

4. The method for hoisting and constructing a large cantilevered steel box girder according to claim 1, characterized in that, When assembling the steel box girder cantilever arm installation and fixing bracket, one end of the inner support rod (29) and the support short rod (30) is fixed on the inclined support plate (31), and the other end is fixed on the transverse steel base frame (28).

5. The method for hoisting and constructing a large cantilevered steel box girder according to claim 1, characterized in that, In step seven, the frame is constructed from horizontal support steel pipes (42) and vertical support steel pipes (43).

6. The method for hoisting and constructing a large cantilevered steel box girder according to claim 1, characterized in that, In step five, when installing the cantilever steel box girder (36), the extendable baffle is erected and the cantilever steel box girder (36) is placed on the inclined support plate (31). The position of the cantilever steel box girder (36) is constrained by the extendable baffle (37) to prevent it from slipping. When the cantilever steel box girder (36) is adjusted to the installation position, the extendable baffle (37) is laid flat to release the constraint on the extendable baffle (37). The cantilever steel box girder (36) is then moved to the installation position and installed.

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