CN214695113U - Back-loading cantilever arm structure of spine beam bridge - Google Patents

Abstract

The utility model provides a spine beam bridge after-loading cantilever arm structure, which is suitable for a spine beam bridge with a segment prefabricated composite cross section, and comprises a core longitudinal beam, a back-loading cantilever arm, a prefabricated bearing, a back-loading cantilever arm top plate longitudinal joint, a prefabricated bottom die, a back-loading cantilever arm top plate, a back-loading cantilever arm ribbed plate and the like; the rear cantilever arm is a prefabricated concrete member assembled by sections; each prefabricated section of the rear cantilever arm comprises two cantilever arm rib plates and cantilever arm top plates in corresponding ranges; the rear cantilever rib plate is provided with a prefabricated bearing at the lower edge of the root part and forms a group of vertical supports together with the bearing of the core longitudinal beam; the rear-loading cantilever arm top plate is provided with a longitudinal joint between the adjacent prefabricated top plates in the longitudinal direction of the longitudinal bridge; and the bottom edges of the prefabricated top plates on two sides of the longitudinal wet joint are respectively provided with a prefabricated bottom die. The utility model overcomes the technical bottleneck of jumbo size festival section roof beam transportation, construction among the prior art, the back dress that makes compound cross-section backbone roof beam is picked arm festival section and is connected reliably, construction convenient with the core longeron, has promoted the design and the construction key technology of the prefabricated concrete bridge of assembling of festival section.

Description

Back-loading cantilever arm structure of spine beam bridge

Technical Field

The utility model belongs to the technical field of bridge member and construction thereof, especially a back cantilever arm structure of spine beam bridge.

Background

The segmental precast and assembled concrete bridge accords with the national industry development direction, has the advantages of environmental protection, small influence on environment and traffic, convenient transportation, quick construction, attractive appearance, durability, low whole life cost and the like, is widely popularized and applied in domestic railway, highway, rail transit and municipal engineering in recent years, and achieves good use effect.

At present, for a large prefabricated section box girder with a wider bridge deck, the transportation size and the hoisting weight restrict, a split type multi-box section is adopted in a conventional method, machines and tools of the scheme have high equipment investment, a pier top beam has high construction difficulty, the construction period is long, the construction cost is high, and the landscape effect is difficult to satisfy. In order to solve the difficult problems of transportation and construction of wide bridge section beams, the concept of a spine beam with a composite section is required to be provided, namely, a section is decomposed into a core longitudinal beam and a rear cantilever arm. Because the construction time sequence that the rear cantilever arm is erected step by step after the core longitudinal beam is formed is followed, the construction progress of the main stressed structure is not influenced by the installation of the cantilever arm, and the composite section spine beam is an efficient construction method at the same time.

Aiming at the structural characteristics and the construction method of the ridge beam with the composite section, a rear cantilever arm and a longitudinal joint structure thereof of a ridge beam bridge are required to be provided, so that the cantilever arm sections are convenient and fast to prefabricate and construct, and meanwhile, a reliable structural system can be formed by the cantilever arm sections and the core longitudinal beam, so that the cantilever arm sections have structural performance which is not inferior to that of the traditional cast-in-place beam. At present, the conventional prefabricated segment assembly can adopt two types of seam connection structures such as dry joint or wet joint. For composite section spinal bridges, the transverse splice may optionally be a wet or matched dry splice, but the advantage of using a wet splice for the longitudinal seams is more pronounced. According to the scheme, the rear cantilever arm section does not need to be matched with the core longitudinal beam for prefabrication, the cantilever arm section can be conveniently and rapidly prefabricated in batches in a factory, and the cantilever arm section can better adapt to complex conditions such as ultrahigh gradual change, curve sections and the like. Considering that the single ribbed slab cantilever has the risk of lateral overturning in the construction stage, the double ribbed slab cantilever structure with the prefabricated bearing is provided, stable vertical support can be provided for a rear cantilever in the construction stage, the supporting procedures of erection and dismantling of a large number of supports on site are saved, the hoisting times can be reduced due to a large section modulus, and the construction progress is greatly accelerated. In addition, considering that a great number of wet joints exist discretely along the longitudinal bridge direction, if the working procedure of building templates one by one, pouring the wet joints and removing the templates after the maintenance is finished exists in a construction site, the construction efficiency and the construction quality are seriously restricted, and the high-altitude operation risk is greatly increased, so that a wet joint solution with a prefabricated bottom die is provided.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome the technical bottleneck problem of the transportation of jumbo size festival section roof beam, construction that exists among the prior art, provide the backbone girder bridge that can be under construction fast and back the cantilever arm structure, reach the back of composite cross section backbone roof beam and back the cantilever arm festival section be connected reliably, the construction is convenient with the core longeron, promote the design and the construction key technology of festival section prefabrication assembly concrete bridge, promote the purpose of the prefabricated development of assembling the technique of festival section roof beam.

In order to realize the purpose of the utility model, the technical proposal of the back cantilever arm structure of the spine girder bridge provided by the utility model is that:

a spine beam bridge post-loading cantilever arm structure is suitable for a spine beam bridge with a composite section prefabricated by segments and comprises a core longitudinal beam, a post-loading cantilever arm, a prefabricated bearing, a post-loading cantilever arm top plate longitudinal joint, a prefabricated bottom die, a post-loading cantilever arm top plate and a post-loading cantilever arm ribbed plate; the rear cantilever arm is a prefabricated concrete member assembled by sections and follows the construction time sequence of gradually erecting the finished core longitudinal beam; each prefabricated section of the rear cantilever arm comprises two cantilever arm rib plates and cantilever arm top plates in corresponding ranges; the lower edge of the root part of the rear cantilever rib plate is provided with a prefabricated bearing which is matched with the bearing of the core longitudinal beam to form a group of vertical supports; the cast-in-place reinforced concrete joint, namely the longitudinal joint of the rear-mounted cantilever top plate, is arranged between the adjacent prefabricated top plates in the longitudinal bridge direction; and the longitudinal wet joint is respectively provided with an integrated precast concrete disassembly-free type template, namely a precast bottom template, at the bottom edges of the precast top plates at the two sides.

Furthermore, due to the adoption of a wet joint structure, the rear-mounted cantilever arm segment is not required to be matched and prefabricated with the core longitudinal beam, so that the rear-mounted cantilever arm segment can be conveniently and rapidly prefabricated in batches in a factory; after the core longitudinal beam part of the spine beam is finished on site, a prefabricated rear-mounted cantilever arm segment (including a prefabricated bottom die) can be installed, the prefabricated bearing can conveniently provide vertical support for the cantilever arm segment, and relative stability of the rear-mounted cantilever arm and the core longitudinal beam is ensured; after the construction of transverse joints (including joints between rear cantilever rib plates and core longitudinal beam webs/rib plates and joints between rear cantilever top plates and core beam top plates) between rear cantilever arms and core longitudinal beams is completed, longitudinal wet joint concrete between the two adjacent rear cantilever top plates can be quickly poured without additionally erecting a bottom die.

Furthermore, the single rear cantilever arm section consists of a whole cantilever arm top plate and two cantilever arm ribbed plates which play a supporting role below the top plate, and the hoisting times and the construction period can be saved due to the larger section modulus; the lower edge of the cantilever rib plate is provided with a prefabricated support; the lower edge of the cantilever arm top plate is provided with a prefabricated bottom die; the transverse width of the rear loading cantilever arm should not exceed 2/5 of the total width of the bridge, and preferably 1/4-1/3 of the total width of the bridge; the space between the arm-raising ribbed plates is not more than the transverse size of the arm-raising, preferably 2-4 m; the longitudinal size (including the prefabricated bottom die) of the top plate of the cantilever arm is twice of the space between rib plates of the cantilever arm.

Further, when the bridge is located in the straight line segment, the top plate of the single cantilever arm segment is rectangular; when the bridge is located in the circular curve section, the top plate of the single cantilever arm section is in a fan shape.

Furthermore, the prefabricated support is formed by combining a pair of reinforced concrete members and comprises an upper support and a lower support; the upper bearing is positioned on the rear-loading cantilever arm segment, the lower bearing is positioned on the core longitudinal beam, and the structural shapes of the upper bearing and the lower bearing are matched; and an epoxy resin adhesive is smeared on the contact surface between the upper bearing and the lower bearing.

Further, the transverse joint of the rear cantilever arm can adopt 1) a wet joint of cast-in-place reinforced concrete, 2) a dry joint without cast-in-place concrete or 3) a mixed connection of the two modes.

Furthermore, the prefabricated bottom moulds of the adjacent cantilever arm sections are tightly combined, concrete is poured from the bridge floor to finish wet joints, and a large number of working procedures of erecting and dismantling templates can be omitted; pre-buried steel bars are reserved on the prefabricated cantilever top plates and respectively extend into the wet joint area; common concrete is poured into the wet joint, and the embedded steel bars are annular; preferably, the wet joint is poured with high-performance concrete, and the embedded steel bars are linear short steel bars.

Further, the prefabricated bottom die is a reinforced concrete member prefabricated in a factory and arranged on the bottom edge of the cantilever top plate; preferably, the water stop rubber strip is arranged on the side edge of the prefabricated bottom die, so that the sections of the later-installed cantilever arms are closely attached, and the slurry leakage in the concrete pouring link is avoided; preferably, in order to avoid the weakening of the thickness of the prefabricated template to the wet joint of the top plate and ensure the reliable force transmission of the longitudinal wet joint of the cantilever arm, the longitudinal joint of the top plate of the cantilever arm and the standard section of the top plate of the cantilever arm are of equal thickness after being taken, meanwhile, a thickness gradual change section is designed and arranged at the joint of the prefabricated bottom die and the top plate of the cantilever arm, and the edge of the prefabricated bottom die forms an inclined slope surface.

The utility model provides a pair of after spinal beam bridge the beneficial effect of cantilever arm structure as follows:

1. the utility model discloses a reasonable back dress is chosen arm and vertical seam structure thereof makes the back dress and chooses the arm segment section and need not match the prefabrication with the core longeron, has ensured to choose the arm segment section and can prefabricate in convenient quick batch in mill. Meanwhile, reliable connection and convenient construction of rear cantilever arm sections are ensured, a reliable spine beam system with a composite cross section can be formed, the spine beam system has structural performance which is not inferior to that of a traditional cast-in-place beam, and the integral stress has obvious advantages compared with that of a separated multi-box section which is widely adopted at present.

2. The utility model provides a take prefabricated bearing's double ribbed slab cantilever structure can for back cantilever arm provides stable vertical braces at the construction stage, has practiced thrift on-the-spot a large amount of support of setting up, has demolishd the support process, has avoided single ribbed slab cantilever arm segment's lateral overturning risk simultaneously, and great segment modulus can also save the hoist and mount number of times in a large number, reduction on-the-spot time limit for a project, promotion construction quality, reduction high altitude construction risk.

3. The utility model provides a vertical seam structure that wet seam and prefabricated die block are constituteed, the construction is quick, convenient, combines the prefabrication of customization to pick the arm roof, can match the concrete demand of all kinds of engineering in a flexible way, is applicable to various complicated sections, superelevation gradual change and curve section bridge, has extensive application prospect.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

Fig. 2 is an elevation view of the present invention.

Fig. 3 is a cross-sectional view of the present invention.

Fig. 4 is a top view (straight-line bridge) of the present invention.

Fig. 5 is a top view (circular curve segment bridge) of the present invention.

Fig. 6 is a cross-sectional view of a longitudinal seam of the present invention.

Fig. 7 is an exploded view of the composite section spinal bridge of the present invention after arm picking.

Fig. 8 is an application example of the wet joint of the top plate using the combination of the common concrete and the ring-shaped steel bar of the present invention.

Fig. 9 is an application example of the top plate wet joint using high performance concrete and straight short steel bars.

In the figure:

the device comprises a core longitudinal beam 1, a rear-mounted cantilever arm 2, a prefabricated bearing 3, a rear-mounted cantilever arm top plate longitudinal joint 4, a prefabricated bottom die 5, a water stop rubber strip 6, a thickness gradient section 7, a cantilever arm top plate 8, a cantilever arm ribbed plate 9, a core longitudinal beam cantilever arm ribbed plate 10, embedded steel bars 11, common concrete 12 and high-performance concrete 13.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully and specifically with reference to the accompanying drawings and preferred embodiments, but the scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

The present embodiment employs a spinal bridge post-cantilever arm configuration, as shown in the drawings.

The embodiment is suitable for a segmental prefabricated composite section spine beam bridge and comprises a core longitudinal beam 1, a rear-mounted cantilever arm 2, a prefabricated bearing 3, a rear-mounted cantilever arm top plate longitudinal joint 4, a prefabricated bottom die 5, a rear-mounted cantilever arm top plate 8, a rear-mounted cantilever arm ribbed plate 9 and the like. The cantilever arm 2 is a prefabricated concrete member assembled by sections and follows the construction time sequence of gradually erecting the core longitudinal beam 1 after finishing the construction; each prefabricated section of the rear cantilever arm 2 comprises two cantilever arm ribbed plates 9 and a cantilever arm top plate 8 in a corresponding range; the rear cantilever rib plate 9 is provided with a prefabricated bearing 3 at the lower edge of the root part, and forms a group of vertical supports together with the bearing of the core longitudinal beam; the rear cantilever arm top plate 8 is provided with a cast-in-place reinforced concrete joint 4, namely a longitudinal wet joint, between the adjacent prefabricated top plates in the longitudinal bridge direction; and the longitudinal wet joint 4 is respectively provided with an integrated precast concrete disassembly-free type template, namely a precast bottom die 5, at the bottom edges of the precast top plates 8 at the two sides.

During specific implementation, the rear-loading cantilever arm 2 is hoisted by a bridge deck crane, the core longitudinal beam 1 is hoisted one by one after forming a continuous structure, and a stable vertical support is formed by the prefabricated bearing 3 and the core longitudinal beam 1, so that the further installation is facilitated. Pick 4 wide 550cm in arm roof wet joint, prefabricated die block 5 is that the prefabricated arm roof 8 bottoms of picking of both sides all set up the template of certain thickness, matches the alignment each other, forms the wet joint and exempts from to tear open the template structure.

The construction method of the after-loading cantilever arm 2 and the longitudinal joint 4 thereof comprises the following steps: due to the adoption of a wet joint structure, the adjacent rear-mounted cantilever arm 2 sections do not need to be prefabricated in a matching way, so that the cantilever arm sections can be conveniently and quickly prefabricated in batches in a factory; after the core longitudinal beam 1 of the spine beam is partially finished on site, the prefabricated cantilever arm sections 2 (including the prefabricated bottom die 5) can be installed, the prefabricated bearing 3 can conveniently provide vertical support for the cantilever arm sections, and the relative stability of the rear-mounted cantilever arm 2 and the core longitudinal beam 1 is ensured; after the construction of transverse joints (including joints between rear cantilever rib plates and core longitudinal beam web plates/rib plates and joints between rear cantilever top plates and core beam top plates) between the rear cantilever arms 2 and the core longitudinal beams 1 is completed, longitudinal wet joint concrete between the two adjacent rear cantilever top plates can be quickly poured without additionally erecting a bottom mould.

When concrete implementation, 2 segmentations of arm are chosen in the prefabrication utilize the bridge floor crane to install, and the arm 2 is chosen to the prefabrication hangs to flush with core longeron 1, makes the prefabrication bearing 3 of choosing arm 2 take on the core longeron bearing, matches the butt joint between the two, forms stable vertical support, conveniently indulges horizontal wet joint concrete placement. When the cantilever longitudinal wet joint 4 is poured, an external hanging template is not arranged on the site, and the prefabricated bottom die 5 is used for directly pouring.

The rear loading arm 2 is structured as follows: the single cantilever arm section consists of a whole cantilever arm top plate 8 and two cantilever arm ribbed plates 9 which play a supporting role below the top plate, and the hoisting times and the construction period can be saved due to the larger section modulus; the lower edge of the rib plate is provided with a prefabricated support 3; the lower edge of the top plate is provided with a prefabricated bottom die 5; the transverse width of the cantilever arm should not exceed 2/5 of the total width of the bridge, preferably 1/4-1/3 of the total width of the bridge; the space between the ribbed plates is not more than the transverse size of the cantilever arm, preferably 2-4 m; the longitudinal dimension of the top plate (including the prefabricated bottom die 5) is twice of the space between the rib plates.

In specific implementation, the width of a single cantilever arm segment in the transverse bridge direction is 7.7m, which is about 0.3 time of the total width of the bridge; the single cantilever arm segment comprises two ribbed plates, the length of the cantilever arm segment along the bridge direction is 6m, and the interval of the ribbed plates is 3 m. And a single cantilever arm segment is about 33t heavy, so that the weight is light, and the bridge deck crane is convenient to lift. The transverse size of the prefabricated bearing 3 of the cantilever arm segment is 350mm, and the longitudinal size of the prefabricated bearing is 300mm, wherein the thickness of the prefabricated bearing is equal to that of a rib plate. The prefabricated bearing 3 is arranged at intervals of 3 meters along with the cantilever rib plate and is arranged on the bearing of the core longitudinal beam.

The rear cantilever top plate 8: when the bridge is located on the straight line segment, the top plate of the single cantilever arm segment is rectangular; when the bridge is located in the circular curve section, the top plate of the single cantilever arm section is in a fan shape.

During specific implementation, the top plate section at the top plate longitudinal joint 4 of the cantilever arm section is arranged in a mode of being perpendicular to the middle line of the bridge, and the longitudinal joints of the circular and curved bridge sections can be conveniently spliced.

The support is formed by combining a pair of reinforced concrete members and comprises an upper support and a lower support; the upper bearing is positioned on the rear-loading cantilever arm 2 segment, the lower bearing is positioned on the core longitudinal beam 1, and the structural shapes of the upper bearing and the lower bearing are matched; and an epoxy resin adhesive is coated on the contact surface between the upper bearing and the lower bearing.

When the device is specifically implemented, the cantilever rib plate prefabricated bearing 3 and the core longitudinal beam bearing are matched and prefabricated, and are spliced through an epoxy resin binder. The cementing strength of the epoxy resin binder is not lower than the corresponding index of C60 concrete, the primary curing time is more than 2 hours, the epoxy resin binder is completely cured within 24 hours to reach the cementing strength, and the procedures of gluing, pressurizing and the like are ensured to be completed before curing. The glue layer is uniform, and the thickness is controlled to be 2-3 mm. Measures are taken in the brushing process and the colloid curing process to prevent rainwater invasion and sunlight irradiation. The epoxy-coated joint should be cleaned, in any case free of grease, and cleaned of surface scum.

The transverse joint of the rear-loading cantilever arm 2 can adopt 1) a wet joint of cast-in-place reinforced concrete, 2) a dry joint without cast-in-place concrete or 3) a mixed connection of the two modes.

When the concrete implementation, cantilever rib plate prefabricated bearing 3 is 350mm wide with the bearing of core longeron, and both carry out dry joint through the epoxy binder, set up one wide 550mm, thick 300 mm's wet seam more than the bearing simultaneously, form wholly through embedded reinforcement 11 and core longeron 1.

The longitudinal joint 4 of the rear-loading cantilever arm is characterized in that: the prefabricated bottom moulds 5 of the adjacent cantilever arm sections are tightly combined, concrete is poured from the bridge floor to finish wet joints, and a large number of working procedures of erecting and dismantling templates can be omitted; pre-buried steel bars 11 are reserved on the prefabricated cantilever top plates 8 and respectively extend into the wet joint area; ordinary concrete 12 is poured into the wet joint, and the embedded steel bars 11 are annular; preferably, the wet joint is poured with high-performance concrete 13, and the embedded steel bars 11 are linear short steel bars.

When the concrete implementation is carried out, the prefabricated cantilever top plates 8 on the two sides are both provided with HRB400 annular embedded steel bars 11 with the diameter of 10, and the transverse distance between the annular steel bars is 150 mm. Hoisting the prefabricated arm-picking 2 segments (including the prefabricated bottom die 5) to enable the upper and lower bearings to be in lap joint, locally adjusting the adjacent prefabricated arm-picking 2, enabling the embedded ring-shaped steel bars 11 on the two sides to be arranged in a close-fitting manner from front to back, and ensuring enough welding or lap joint length. After 6 HRB400 full-length transverse steel bars with the diameter of 12 penetrate through the inner part of the ring, C55 common concrete is poured in the wet joint.

The prefabricated bottom die 5 is a reinforced concrete member prefabricated in a factory and is arranged on the bottom edge of the top plate; preferably, the water stop rubber strips 6 are arranged on the side edges of the prefabricated bottom die 5, so that the cantilever arm sections are closely attached, and the slurry leakage in the concrete pouring link is avoided; preferably, in order to avoid the weakening of the thickness of the prefabricated bottom die 5 to the wet joint 4 of the top plate and ensure the reliable force transmission of the vertical wet joint of the cantilever arm, the thicknesses of the wet joint and the standard section of the top plate are equal, meanwhile, a thickness gradual change section 7 is designed and arranged at the joint of the prefabricated bottom die 5 and the top plate, and the edge forms an inclined slope surface.

During specific implementation, the bottom of the prefabricated cantilever top plate 8 is provided with a prefabricated bottom die 5, and the prefabricated bottom dies 5 on the two sides are aligned and closely attached to each other to form a rectangular wet joint area. The edge of the prefabricated bottom die 5 is provided with a 2cm water stop rubber strip 6, the interface is kept dry when the water stop rubber strip 6 is installed, floating slag, dust and sundries on the interface are removed before construction, and the water stop strip 6 is fixed at the installed position by using an adhesive or a high-strength anchor. The prefabricated bottom die 5 has a rectangular cross section, the width is 275mm, the thickness is 40mm, and the concrete label is C55. At prefabricated die block 5 and the combination department of choosing arm roof 8, it is thick to choose arm roof to be thick carries out local reinforcing, by standard 230mm with 1: the ratio of 4 was thickened to 270 mm.

The foregoing is a more detailed description of the invention, taken in conjunction with the accompanying preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described above. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims (12)

1. A spine beam bridge post-loading cantilever arm structure is suitable for a spine beam bridge with a prefabricated composite section of a segment, and comprises a core longitudinal beam (1), a post-loading cantilever arm (2), a prefabricated bearing (3), a post-loading cantilever arm top plate longitudinal joint (4), a prefabricated bottom die (5), a post-loading cantilever arm top plate (8) and a post-loading cantilever arm ribbed plate (9); the method is characterized in that: the rear-mounted cantilever arm (2) is a prefabricated concrete member assembled by sections and follows the construction time sequence of gradually erecting the finished core longitudinal beam (1); each prefabricated section of the afterloading cantilever arm (2) comprises two cantilever arm rib plates (9) and cantilever arm top plates (8) in corresponding ranges; the rear cantilever rib plate (9) is provided with a prefabricated bearing (3) at the lower edge of the root part, and forms a group of vertical supports by matching with the bearing of the core longitudinal beam (1); the rear-mounted cantilever arm top plate (8) is provided with a cast-in-place reinforced concrete joint, namely a rear-mounted cantilever arm top plate longitudinal joint (4), between adjacent prefabricated top plates in the longitudinal bridge direction; and after-loading the longitudinal joint (4) of the top plate of the cantilever arm, the bottom edges of the prefabricated top plates at the two sides are respectively provided with an integrated prefabricated concrete disassembly-free type template, namely a prefabricated bottom die (5).

2. The posterior cantilever arm construction of a spinal beam bridge as claimed in claim 1, wherein: wherein, the single rear-mounted cantilever arm (2) segment consists of a whole cantilever arm top plate (8) and two cantilever arm ribbed plates (9) which play a supporting role below the whole cantilever arm top plate; the lower edge of the cantilever rib plate (9) is provided with a prefabricated bearing (3); the lower edge of the cantilever arm top plate (8) is provided with a prefabricated bottom die (5).

3. A posterior cantilever arm construction of a spine bridge according to claim 2, wherein the lateral width of the posterior cantilever arm (2) should not exceed 2/5 of the total width of the bridge; the space between the cantilever rib plates (9) is not more than the transverse dimension of the rear cantilever (2); the longitudinal size of the cantilever top plate (8) contains a prefabricated bottom die (5) which is twice of the distance between cantilever rib plates (9).

4. A posterior cantilever arm construction of a spine bridge according to claim 3, wherein the lateral width of the posterior cantilever arm (2) is 1/4-1/3 of the total width of the bridge; the space between the cantilever rib plates (9) is 2-4 m.

5. The posterior cantilever arm construction of a spinal beam bridge as claimed in claim 1, wherein: when the bridge is positioned in the straight line section, the top plate (8) of the single rear cantilever arm section is rectangular; when the bridge is located in the circular curve section, the top plate (8) of the single rear cantilever arm section is in a fan shape.

6. The post-loading cantilever arm structure of a spine beam bridge as claimed in claim 1, wherein the prefabricated support (3) is composed of a pair of reinforced concrete members, and comprises an upper support and a lower support; the upper bearing is positioned on the rear-loading cantilever arm (2) segment, the lower bearing is positioned on the core longitudinal beam (1), and the structural shapes of the upper bearing and the lower bearing are matched; and an epoxy resin adhesive is smeared on the contact surface between the upper bearing and the lower bearing.

7. The posterior cantilever arm construction of a spinal beam bridge as claimed in claim 1, wherein: the prefabricated bottom moulds (5) of the adjacent cantilever arm sections are tightly combined, and concrete is poured from the bridge floor to finish a wet joint; and (3) prefabricating a cantilever top plate (8), reserving embedded steel bars (11) and respectively extending into the wet joint area.

8. The structure of a rear cantilever arm of a spine beam bridge according to claim 7, wherein the wet joint is cast with normal concrete, and the embedded steel bars are ring-shaped.

9. The structure of claim 7, wherein the wet joint is poured with high performance concrete, and the embedded steel bars are linear short steel bars.

10. The rear cantilever structure of a spine beam bridge according to claim 1, wherein the prefabricated bottom mold (5) is a prefabricated reinforced concrete member and is arranged at the bottom edge of the cantilever top plate (8).

11. The structure of the rear cantilever arm of the spine beam bridge as claimed in claim 10, wherein the side edge of the prefabricated bottom die (5) is provided with a water-stop rubber strip (6) to ensure that the sections of the rear cantilever arm (2) are closely attached.

12. The structure of the spine beam bridge rear cantilever arm according to claim 10, wherein the longitudinal joint (4) of the top plate of the rear cantilever arm has the same thickness as the standard section of the top plate (8) of the cantilever arm, and a thickness gradually-changing section (7) is arranged at the joint of the prefabricated bottom die (5) and the top plate (8) of the cantilever arm, and the edge of the thickness gradually-changing section forms an oblique slope.

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