CN112281680A - Steel box girder composite lifting system and construction method thereof - Google Patents

Abstract

The invention relates to a steel box girder composite lifting system and a construction method thereof, wherein the steel box girder composite lifting system comprises the following steps: the junction pier is arranged at the junction between water and land; the pushing support is arranged on land and arranged side by side with the junction pier along the longitudinal bridge direction; one end of the main truss structure is fixed on the junction pier through a supporting device, and the other end of the main truss structure is anchored on the pushing support through a rear anchor device; and the lifting device is used for lifting the steel box girder and is fixed on the main truss structure. The steel box girder composite lifting system and the construction method thereof greatly save the using amount of steel, can take the girder in water, and ensure the traffic safety of the under-bridge navigation during the construction period; the device occupies less Yangtze river channel, has light structure, economy and reasonability, simple and clear stress, stable and uniform lifting, continuity and rapidness and strong popularization.

Description

Steel box girder composite lifting system and construction method thereof

Technical Field

The invention relates to the technical field of bridge construction, in particular to a steel box girder composite lifting system and a construction method thereof.

Background

At present, a steel box girder bridge is a common structural form of a bridge, and has the characteristics of light structure dead weight, high torsional rigidity, good wind resistance stability and convenience in construction and maintenance.

In the related technology, in the conventional erection method of the steel box girder bridge, a support method is generally adopted, and the method is mainly characterized in that a floor type support is erected at a boundary pier, then a large-tonnage floating crane is used for hoisting the steel box girder section between pier tops, and then a bridge deck crane is used for installation.

However, the method needs a large-tonnage floating crane, has high requirements on the depth of the water area and high cost, and the erection of the support consumes a large amount of steel, thereby influencing the navigation of the water area under the bridge.

Disclosure of Invention

The embodiment of the invention provides a steel box girder composite lifting system and a construction method thereof, and aims to solve the problems that a large-tonnage floating crane is needed by adopting a support method in the related art, and the navigation of a water area under a bridge is influenced due to the fact that a large amount of steel is consumed by erecting a support.

In a first aspect, a steel box girder composite lifting system is provided, which comprises: the junction pier is arranged at the junction between water and land; the pushing support is arranged on land and arranged side by side with the junction pier along the longitudinal bridge direction; one end of the main truss structure is fixed on the junction pier through a supporting device, and the other end of the main truss structure is anchored on the pushing support through a rear anchor device; and the lifting device is used for lifting the steel box girder and is fixed on the main truss structure.

In some embodiments, the support device comprises: the cross rod is arranged at the top of the junction pier along the transverse bridge direction; and the vertical rod is vertically attached to the surface of the junction pier, the upper end of the vertical rod is hinged to the cross rod, and the lower end of the vertical rod is fixed to the junction pier through an embedded part.

In some embodiments, the support device further comprises: the lapping rods are obliquely arranged in the horizontal plane, one ends of the lapping rods are hinged with the cross rods, and the other ends of the lapping rods are fixed with the junction pier; the inclined rod is obliquely arranged in the vertical surface, one end of the inclined rod is hinged to the cross rod, and the other end of the inclined rod is fixed to the junction pier.

In some embodiments, the posterior anchor device comprises: a steel frame anchored to the incremental launching bracket; the annular plate is used for anchoring the main truss structure and is arranged above the steel frame; the ring plate and the steel frame are fixed through opposite-pulling finish rolling thread steel bars.

In some embodiments, the ring plate is provided with a groove matching the main truss structure, and the main truss structure is accommodated in the groove.

In some embodiments, the main truss structure comprises: a horizontal strut having a first end fixed to the pushing support and a second end fixed to the support device; the rear end of the walkway beam is fixed with the second end of the horizontal support rod through an upright post; and one end of the diagonal draw bar is hinged to the pushing support, and the other end of the diagonal draw bar is hinged to the walkway beam.

In some embodiments, the main truss structure further comprises: one end of the diagonal brace is fixed at the second end of the horizontal brace rod, and the other end of the diagonal brace is fixed with the front end of the walkway beam; and one end of each web member is hinged to the inclined strut, and the other end of each web member is hinged to the walkway beam.

In some embodiments, the horizontal stay bar and the upright post are formed by assembling a plurality of sections of round steel tubes, and two adjacent round steel tubes are connected through a flange plate.

In some embodiments, the lifting device comprises: a girder structure fixed to the main truss structure, the girder structure being provided with a slideway; the lifting jack is arranged on the girder structure and connected with a steel strand used for lifting the steel box girder, and the lifting jack can slide on the slide way along the transverse bridge direction.

In a second aspect, a construction method of the steel box girder composite lifting system is provided, which includes the following steps: pouring and molding the junction pier, and mounting the supporting device on the junction pier; building the pushing support, and installing the rear anchor device on the pushing support; hoisting the main truss structure to the position above the junction pier and the pushing support, fixing one end of the main truss structure to the supporting device, and fixing the other end of the main truss structure to the rear anchor device; hoisting the lifting device to the main truss structure.

The technical scheme provided by the invention has the beneficial effects that:

the embodiment of the invention provides a steel box girder combined type lifting system and a construction method thereof, wherein one end of a main girder structure is fixed on a junction pier through a supporting device, the other end of the main girder structure is anchored on a pushing support through a rear anchor device, and the lifting device is fixed on the main girder structure, so that the constructed junction pier is used as a supporting point of the lifting device in the whole lifting system, the pushing support is used as a rear anchoring point of the lifting device, the supporting height from the lifting device to a river bed is reduced, the use amount of steel is greatly saved, a girder can be taken out from water, and the traffic safety of underbridge navigation during construction is guaranteed; and need not build independent support and hoist and mount steel case roof beam through large-tonnage floating crane to reduce the input of large-scale aquatic lifting equipment, the fortune roof beam ship is gone and is promoted to utilizing this system behind the hoisting device below, has accomplished green, occupies the changjiang river channel less, and the structure is light, economical reasonable, and the atress is simple clear and definite, promotes steady at the uniform velocity, in succession swift, and the popularization nature is strong.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a steel box girder composite lifting system according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of A-A of FIG. 1;

FIG. 3 is a schematic structural diagram of a cross bar and a lap bar according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a rear anchor device provided in accordance with an embodiment of the present invention;

FIG. 5 is a schematic structural view of a main truss structure provided in an embodiment of the present invention;

FIG. 6 is a schematic cross-sectional view of B-B of FIG. 1.

In the figure: 1. a junction pier; 2. pushing the bracket; 3. a support device; 31. a cross bar; 32. a vertical rod; 33. a lap joint rod; 34. a diagonal bar; 35. embedding parts; 4. a rear anchor device; 41. a steel frame; 42. a ring plate; 421. a groove; 43. oppositely pulling and finish rolling the twisted steel; 44. an anchor rod; 45. an anchor plate; 5. a main truss structure; 51. a horizontal stay bar; 511. a first end; 512. a second end; 52. a walkway beam; 53. a column; 54. a diagonal member; 55. bracing; 56. a web member; 57. a connecting system; 6. a lifting device; 61. a girder structure; 62. a jack base frame; 63. a jack; 64. steel strand wires; 65. a reel; 66. guiding a cable; 7. a steel box girder.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The embodiment of the invention provides a steel box girder combined type lifting system and a construction method thereof, which can solve the problems that a large-tonnage floating crane is needed by adopting a support method in the related art, and the navigation of a water area under a bridge is influenced by the fact that a large amount of steel is consumed by erecting a support.

Referring to fig. 1, a steel box girder composite lifting system according to an embodiment of the present invention includes: the junction pier 1 is arranged at the junction between water and land, and the common junction pier 1 is arranged at the position close to the land on the edge of a river; the pushing support 2 is arranged on the land and is arranged side by side with the boundary pier 1 along the longitudinal bridge direction, namely, the pushing support 2 is arranged behind the boundary pier 1 along the longitudinal bridge direction; one end of the main truss structure 5 is fixed on the junction pier 1 through a supporting device 3, and the other end of the main truss structure is anchored on the pushing support 2 through a rear anchor device 4, so that the main truss structure 5 is fixed on the junction pier 1 along the longitudinal bridge direction; a hoisting device 6 for hoisting steel box girder 7, it is fixed in main truss structure 5, makes hoisting device 6 fix on juncture pier 1 through main truss structure 5 for whole hoisting system uses juncture pier 1 that has been under construction as hoisting device 6's strong point, and the top pushes away support 2 as hoisting device 6 back anchor point, reduces the support height of hoisting device 6 to the riverbed, saves the steel use amount greatly.

Referring to fig. 1 and 2, in some embodiments, the support device 3 may include: the cross rod 31 can be arranged at the top of the junction pier 1 along the transverse bridge direction, and can be fixed with the junction pier 1 through the embedded part 35 and the finish-rolled threaded steel bars; and the montant 32 of vertical attached on juncture pier 1 surface, in this embodiment, the montant 32 sets up in juncture pier 1's relative both sides, the upper end of montant 32 can be articulated with horizontal pole 31, the lower extreme can be fixed with juncture pier 1 through built-in fitting 35, through setting up crisscross horizontal pole 31 and montant 32 of violently indulging, make strutting arrangement 3 firm be fixed in juncture pier 1's top, and montant 32 is connected with horizontal pole 31 is articulated, can release the moment of flexure of montant 32 and horizontal pole 31 junction, guarantee that the vertical load on horizontal pole 31 transmits to montant 32, montant 32 passes to juncture pier 1 again, in this embodiment, the preferred reinforcing bar of built-in fitting 35.

Referring to fig. 1 to 3, preferably, the supporting device 3 may further include: the lapping rod 33 is obliquely arranged in the horizontal plane, one end of the lapping rod 33 is welded and fixed with the cross rod 31, and the other end of the lapping rod 33 is fixed with the boundary pier 1, namely, the lapping rod 33 is obliquely arranged relative to the boundary pier body, so that the lapping rod 33, the cross rod 31 and the boundary pier body form a stable triangular structure; the slope sets up the down tube 34 in the vertical plane, the one end of down tube 34 is articulated with horizontal pole 31, the other end is fixed with juncture pier 1, because down tube 34 also inclines to set up, make down tube 34, horizontal pole 31 also form stable triangle-shaped structure with juncture pier 1 three, thereby improve the holistic stability of strutting arrangement 3, down tube 34 is articulated with horizontal pole 31, can release the moment of flexure of down tube 34 and horizontal pole 31 junction, guarantee that the vertical load on the horizontal pole 31 transmits down tube 34, down tube 34 passes juncture pier 1 again.

Referring to fig. 1 and 4, in some embodiments, the posterior anchor device 4 may include: a steel frame 41 which can be anchored on an anchor beam at the top of the pushing support 2; a ring plate 42 for anchoring the main truss structure 5, provided above the steel frame 41; the ring plate 42 can be fixed through the finish rolling twisted steel 43 of drawing to the steelframe 41 with the steelframe 41, in this embodiment, all be equipped with the finish rolling twisted steel 43 of drawing in the both sides of ring plate 42, can closely fix ring plate 42 and steelframe 41 through the finish rolling twisted steel 43 of drawing, wherein, still can press from both sides between ring plate 42 and the steelframe 41 and be equipped with stock 44, the preferred cylindric of stock 44, can promote the height of ring plate 42 through setting up stock 44, be convenient for support main truss structure 5 at certain height, and cylindric stock 44 has better bending strength.

Referring to fig. 1 and 4, in some alternative embodiments, the ring plate 42 may have a groove 421 matching with the main truss structure 5, and the main truss structure 5 is accommodated in the groove 421, specifically, when the main truss structure 5 is cylindrical, the cross section of the groove 421 is also arc-shaped, and when the main truss structure 5 is square, the cross section of the groove 421 is also square, and by providing the groove 421 matching with the structure, the main truss structure 5 may be clamped in the groove 421, so that the positioning is accurate, the main truss structure is not easy to detach, the main truss structure 5 may be limited from rotating in a horizontal plane, and the main truss structure 5 and the ring plate 42 may be welded and fixed.

Referring to fig. 1 and 4, preferably, the rear anchor device 4 may further include two anchor plates 45 arranged in parallel and spaced apart, the lower ends of the two anchor plates extend downward into the anchor rods 44 and are welded to the anchor rods 44, and the upper ends of the two anchor plates extend upward through the ring plate 42 and the main truss structure 5 and are welded to the ring plate 42 and the main truss structure 5, and the anchor plates 45 may connect the anchor rods 44, the ring plate 42 and the main truss structure 5 into a whole.

Referring to fig. 1 and 5, in some embodiments, the main truss structure 5 may include two pieces of trusses, wherein a single piece truss may include: a horizontal stay 51 having a first end 511 fixed to the pushing support 2 and a second end 512 fixed to the support device 3, such that the horizontal stay 51 is supported on the abutment pier 1 along the longitudinal direction; the walkway beams 52 are assembled by adopting H-shaped steel and equal-strength joints, the rear ends of the walkway beams are fixed with the second ends 512 of the horizontal support rods 51 through the upright columns 53, namely, the upright columns 53 are vertically fixed at the second ends 512 of the horizontal support rods 51, the walkway beams can be supported at a certain height through the upright columns 53, and the front ends of the walkway beams 52 can extend forwards to exceed the junction piers 1, so that the walkway beams 52 can be positioned above the river surface, and the lower parts of the walkway beams cannot be shielded by the junction piers 1, thereby being convenient for hoisting the steel box beams 7; the diagonal draw bar 54, preferably a round steel tube, has one end hinged to the pushing support 2 and the other end hinged to the walkway beam 52, specifically, the rear end of the diagonal draw bar 54 may be hinged to the anchor plate 45 of the pushing support 2 through a pin shaft, so that the rear end of the diagonal draw bar 54 is anchored to the pushing support 2, and the front end of the diagonal draw bar 54 is hinged to the rear end of the walkway beam 52, so that the diagonal draw bar 54 tensions the walkway beam 52 at the rear, and the walkway beam 52 is prevented from inclining to the front and the lower.

Referring to fig. 1 and 5, preferably, the horizontal brace 51 and the upright column 53 may be assembled from multiple sections of round steel pipes, the multiple sections of round steel pipes are sequentially connected end to form the horizontal brace 51, the multiple sections of steel pipes are sequentially connected end to form the vertical upright column 53, the lower end of the upright column 53 may be welded and fixed to the second end 512 of the horizontal brace 51, wherein two adjacent round steel pipes forming the horizontal brace 51 may be connected by a flange, two adjacent round steel pipes forming the upright column 53 may also be connected by a flange, and the horizontal brace 51 and the upright column 53 are both made of round steel pipes, so that the assembled horizontal brace 51 and upright column 53 have better strength and bending resistance.

Referring to fig. 1 and 5, in some alternative embodiments, the single-piece truss may further include: one end of the diagonal brace 55 is fixed to the second end 512 of the horizontal brace 51, and the other end of the diagonal brace is fixed to the front end of the walkway beam 52, so that the lower end of the diagonal brace 55 is fixed to the upright 53 and the second end 512 of the horizontal brace 51 at the same point, and in the embodiment, the diagonal brace 55 is preferably fixed by welding, and when the upright 53 supports the rear end of the walkway beam 52, the diagonal brace 55 can be supported to the front end of the walkway beam 52, thereby improving the stability of the diagonal brace 55; a plurality of web members 56, preferred circular steel tube, its one end articulates in bracing 55, and the other end articulates in walkways roof beam 52, and in this embodiment, web member 56 articulates in the middle part of bracing 55, through setting up web member 56, makes set up a plurality of strong points between walkways roof beam 52 and the bracing 55, and stability is better, and adopts the articulated connection to release the moment of flexure.

Referring to fig. 1, preferably, a connection system 57 may be further provided between the two trusses, and the connection system 57 may connect the two parallel diagonal braces 55, the two parallel vertical columns 53, and the two parallel walkway beams 52, so that the two individual trusses are connected into a whole through the connection system 57.

Referring to fig. 1, 2 and 5, in some embodiments, the lifting device 6 may be mounted to a front end of the walkway beam 52, and the lifting device 6 may include: a girder structure 61 fixed on the main truss structure 5, wherein the girder structure 61 can be provided with a slideway along the transverse bridge direction, and a jack underframe 62 can be arranged on the slideway so that the jack underframe 62 can slide on the slideway; the jack 63 is positioned above the girder structure 61, the jack 63 can be fixed on the jack underframe 62, the jack 63 can be connected with a steel strand 64 for lifting the steel box girder 7, and the jack 63 can slide along the transverse bridge direction on the slide way along with the jack underframe 62, so that the convenience and stability in walking and sliding when the lifting device 6 lifts the steel box girder 7 are ensured; and the lifting device 6 can be provided with different numbers of jacks 63 according to the hoisting load, and the continuous jacks 63 with multiple safety devices are adopted, so that the steel box girder 7 is ensured to be lifted in place efficiently and safely.

Referring to fig. 1 and 6, in some alternative embodiments, the lifting device 6 may further include a drum 65 mounted on the jack base frame 62, the steel strand 64 may be wound on the drum 65, and the drum 65 may move along the cross bridge along with the jack 63, a guide cable 66 may be further disposed between the jack 63 and the drum 65, the steel strand 64 connected to the jack 63 may be connected to the drum 65 through the guide cable 66, and the steel cable may be extended according to a predetermined route by disposing the guide cable 66, so as to guide the steel strand 64 wound on the drum 65 to the vertical jack 63.

The embodiment of the invention also provides a construction method of the steel box girder composite lifting system, which comprises the following steps:

step 1: and (3) casting and molding the boundary pier 1, and installing a supporting device 3 on the boundary pier 1.

In some embodiments, in step 1, when the abutment pier 1 is poured, an embedded part 35 for fixing the supporting device 3 may be disposed at a predetermined position of the abutment pier 1.

Step 2: and (3) building a pushing support 2, and installing a rear anchor device 4 on the pushing support 2.

In some embodiments, in step 2, when the pushing support 2 is built, an anchor beam is installed on the top of the pushing support 2, and the rear anchor device 4 is fixedly arranged on the anchor beam.

And step 3: and hoisting the main truss structure 5 to the upper part of the boundary pier 1 and the pushing support 2, fixing one end of the main truss structure 5 to the supporting device 3, and fixing the other end of the main truss structure 5 to the rear anchor device 4.

In some embodiments, in step 3, the main truss structure 5 may include horizontal struts 51, vertical columns 53, walkway beams 52, diagonal braces 54, diagonal braces 55; hoist main truss structure 5 to juncture pier 1 and top and push away 2 tops of support to be fixed in strutting arrangement 3 with main truss structure 5's one end, be fixed in back anchor device 4 with main truss structure 5's the other end, specifically can include: and respectively hoisting the horizontal stay bar 51, the upright 53 and the inclined stay 55 to a designed position in sequence through a tower crane, rechecking and then installing the horizontal stay bar 51, the upright 53 and the inclined stay 55 into a whole, wherein the front end of the horizontal stay bar 51 is fixed on the supporting device 3, the rear end of the horizontal stay bar 51 is fixed on the rear anchor device 4, then the walkway beam 52 and the inclined stay bar 54 are further arranged, and finally, the connecting system 57 of the main truss structure 5 is welded.

And 4, step 4: hoisting means 6 are hoisted to the main girder structure 5.

In some embodiments, in step 4, the lifting device 6 may be hoisted above the main girder structure 5 by using a tower crane, and the installation work is completed.

In some alternative embodiments, after step 4, the steel box girder 7 may be transported by floating directly under the lifting device 6, and the wire rope of the lifting device 6 is lowered to the hoisting point of the steel box girder 7 and the hoisting point is installed.

In some embodiments, after step 4, the lifting device 6 includes a jack 63, the steel box girder 7 is lifted to the designed height by the jack 63, and the pushing construction is performed by the pushing support 2 after the steel box girder 7 is aligned and connected with the guide beam or the erected steel box girder 7.

And repeating the steps until all the steel box girders 7 are lifted and erected.

The principle of the steel box girder composite lifting system and the construction method thereof provided by the embodiment of the invention is as follows:

one end of the main truss structure 5 is fixed on the junction pier 1 through the supporting device 3, the other end of the main truss structure is anchored on the pushing support 2 through the rear anchor device 4, and the lifting device 6 is fixed on the main truss structure 5, so that the constructed junction pier 1 of the whole lifting system is used as a supporting point of the lifting device 6, the pushing support 2 is used as a rear anchoring point of the lifting device 6, the supporting height from the lifting device 6 to a river bed is reduced, the use amount of steel is greatly saved, a beam can be taken out from water, and the traffic safety of underbridge navigation during construction is guaranteed; and need not build independent support and hoist steel case roof beam 7 through large-tonnage floating crane to reduce the input of large-scale aquatic lifting equipment, the fortune roof beam ship is gone and is promoted to utilizing this system behind hoisting device 6 below, has accomplished green, occupies the Changjiang river channel less, and light, economical and reasonable structure, the atress is simple clear and definite, promote steady at the uniform velocity, in succession swift, the popularization nature is strong, and can ensure high-efficient safe completion steel case roof beam 7's promotion, installation work.

In the description of the present invention, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are merely for convenience in 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 in a specific orientation, and operate, and thus, should not be construed as limiting the present invention. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

It is to be noted that, in the present invention, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The utility model provides a steel box girder combined type hoist system which characterized in that, it includes:

the junction pier (1) is arranged at the junction between water and land;

the pushing support (2) is arranged on the land and is arranged side by side with the boundary pier (1) along the longitudinal bridge direction;

one end of the main truss structure (5) is fixed on the junction pier (1) through a supporting device (3), and the other end of the main truss structure is anchored on the pushing support (2) through a rear anchor device (4);

and the lifting device (6) is used for lifting the steel box girder (7) and is fixed on the main truss structure (5).

2. A steel box girder composite lifting system according to claim 1, wherein the supporting means (3) comprises:

the cross bar (31) is arranged at the top of the boundary pier (1) along the transverse bridge direction;

and vertical attached in montant (32) on juncture pier (1) surface, the upper end of montant (32) with horizontal pole (31) are articulated, the lower extreme pass through built-in fitting (35) with juncture pier (1) is fixed.

3. A steel box girder composite lifting system according to claim 2, wherein the supporting means (3) further comprises:

the lapping rods (33) are obliquely arranged in the horizontal plane, one ends of the lapping rods (33) are hinged with the cross rods (31), and the other ends of the lapping rods (33) are fixed with the boundary pier (1);

the inclined rod (34) is obliquely arranged in the vertical plane, one end of the inclined rod (34) is hinged to the cross rod (31), and the other end of the inclined rod is fixed to the junction pier (1).

4. A steel box girder composite lifting system according to claim 1, wherein the rear anchor means (4) comprises:

a steel frame (41) anchored to the pushing bracket (2);

a ring plate (42) for anchoring the main truss structure (5) and arranged above the steel frame (41);

the ring plate (42) and the steel frame (41) are fixed through counter-pulling finish rolling threaded steel bars (43).

5. The steel box girder composite lifting system of claim 4, wherein:

the ring plate (42) is provided with a groove (421) matched with the main truss structure (5), and the main truss structure (5) is contained in the groove (421).

6. A steel box girder composite lifting system according to claim 1, wherein the main girder structure (5) comprises:

a horizontal stay (51) having a first end (511) fixed to said pushing support (2) and a second end (512) fixed to said supporting means (3);

a walkway beam (52) whose rear end is fixed to the second end (512) of the horizontal stay (51) by a pillar (53);

and one end of the diagonal draw bar (54) is hinged to the pushing support (2), and the other end of the diagonal draw bar is hinged to the walkway beam (52).

7. A steel box girder composite lifting system according to claim 6, wherein the main girder structure (5) further comprises:

one end of the diagonal brace (55) is fixed to the second end (512) of the horizontal brace rod (51), and the other end of the diagonal brace is fixed to the front end of the walkway beam (52);

and a plurality of web members (56) having one end hinged to the diagonal brace (55) and the other end hinged to the walkway girder (52).

8. The steel box girder composite lifting system of claim 6, wherein:

the horizontal support rods (51) and the upright columns (53) are formed by assembling a plurality of sections of round steel tubes, and the adjacent round steel tubes are connected through flanges.

9. A steel box girder composite lifting system according to claim 1, wherein the lifting means (6) comprises:

a girder structure (61) fixed to the main girder structure (5), the girder structure (61) being provided with a slideway;

and the lifting jack (63) is arranged on the girder structure (61), the lifting jack (63) is connected with a steel strand (64) used for lifting the steel box girder (7), and the lifting jack (63) can slide on the slide way along the transverse bridge direction.

10. A construction method of a steel box girder composite lifting system according to any one of claims 1 to 9, comprising the steps of:

pouring and molding the junction pier (1), and installing the supporting device (3) on the junction pier (1);

building the pushing support (2), and installing the rear anchor device (4) on the pushing support (2);

hoisting the main truss structure (5) to the position above the junction pier (1) and the pushing support (2), fixing one end of the main truss structure (5) to the supporting device (3), and fixing the other end of the main truss structure (5) to the rear anchor device (4);

hoisting the lifting device (6) to the main girder structure (5).

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