CN117431821A - Single cantilever construction combined bridge and construction method - Google Patents

Abstract

The invention discloses a single cantilever construction combined bridge and a construction method, wherein tunnel construction is firstly carried out on two sides of a V-shaped trough respectively, then a bottom plate of a tunnel portal section is excavated downwards to form a working space and zero section casting construction is carried out, a counterweight section is constructed at one end of the zero section far away from the V-shaped trough, and an anchoring device is constructed at the counterweight section to anchor the counterweight section and a rock body into a whole; starting from zero sections at two sides of the V-shaped trough, constructing the cantilever section in sections, and installing a tensioning stiffening stay cable to ensure the linearity of the cantilever section in the construction process; then carrying out closure section construction; after the folding sections harden, removing hanging baskets on the bridge, and then carrying out stiffening steel truss construction on the bridge deck; and finally, constructing the auxiliary engineering of the bridge, and completing the construction of the single cantilever construction combined bridge of the V-shaped gullies. The invention realizes single cantilever pouring construction by using the counterweight section, the stay cable, the steel truss and the anchoring device, and the span can reach 40-200 m, thereby shortening the construction period and reducing the influence on the environment.

Description

Single cantilever construction combined bridge and construction method

Technical Field

The invention belongs to the field of bridge engineering, relates to a bridge crossing V-shaped valleys, and in particular relates to a single cantilever construction combined bridge and a construction method.

Background

The bridge is a structure crossing the obstacle, a large number of bridge crossing valleys exist in southwest mountain areas of China, various densely distributed highway and railway networks are met, and bridge crossing V-shaped valleys inevitably appear. The V-shaped gully is large in depth from the bridge deck to the valley bottom, difficult steep slopes are arranged on two sides, the condition of building a bracket is generally not provided under the terrain condition, the bracket construction risk is high, the economical efficiency is poor, a construction method without the bracket is selected when the bridge scheme is designed, and two ends of the bridge are directly adjacent to a tunnel.

When the crossing range of the bridge crossing the V-shaped gully is more than 200m, the arch bridge is selected to be crossed, but the arch bridge engineering cost is high, the construction process is complex, the construction risk and the construction period are long, and the bridge is often a control engineering restricting the engineering construction;

when the span is smaller than 40m, the prefabricated simply supported beams can be selected to span, one span is adopted, long tunnels are arranged on two sides of the span, but the large-scale effect cannot be formed by adopting the bridge girder erection equipment, so that the economy is not good.

When the span is in the range of 40-200 m, the T-shaped rigid frame bridge is mainly selected from the safety and economical aspects of construction. However, the bridge type can bring other problems, such as high pier, even more than 100 meters, large section of the lower part of the pier, and back-invasion of the flood area of the gullies, so that the erosion develops to the mountain bottoms at two sides to cause slope collapse, and the engineering safety is affected. Meanwhile, the construction of the high pier is also quite large in engineering difficulty and cost, and is an unobtainable scheme choice.

If a new bridge type without bridge pier can be provided, the application range of the span is wider, and the span can cover the range of 30 m-300 m, the bridge type with the V-shaped valley landform is very competitive.

Disclosure of Invention

The invention aims to provide a single cantilever construction combined bridge for V-shaped valleys and a construction method thereof, which are used for replacing a T-shaped rigid frame bridge in the prior art so as to achieve the purposes of reducing cost, improving safety and reducing damage to the environment.

As shown in fig. 1, a T-shaped rigid frame bridge 100, which is often used when constructing a bridge in a V-shaped valley with a span ranging from 40m to 200m in the prior art, is used as a middle rigid frame pier 110 in the middle valley bottom of a V-shaped valley 300, and the zero-number section is positioned at the top and two side tunnel openings of the middle rigid frame pier 110, and is constructed simultaneously from the middle rigid frame pier and the two side tunnel openings during construction. The invention improves the T-shaped rigid frame bridge in the prior art, cancels the middle rigid frame pier, sets the zero-number sections at tunnel openings at two sides of the V-shaped gullies, sets a counterweight section and an anchoring device at one side of each zero-number section, which is not a cantilever, and balances unbalanced bending moment at two sides of the zero-number section during cantilever pouring construction.

In order to solve the problems, the invention adopts the following technical scheme:

a single cantilever construction combined bridge for V-shaped gullies comprises a zero number section, a counterweight section, a cantilever section, a folding section, a stiffening stay cable and a stiffening steel truss;

the zero number sections are two and are respectively arranged in tunnel openings at two sides of the V-shaped gully and used for providing a fulcrum of the combined bridge, and the weight on the bridge is transmitted to the tunnel bottom plate through the support and then is transmitted into the ground;

the outer ends of the two cantilever sections are respectively connected with two zero sections, and the inner sides of the two cantilever sections are connected through a folding section;

one side of each zero segment, which corresponds to the corresponding cantilever segment, is provided with a counterweight segment, and the counterweight segments are anchored on the rock mass at the bottom in the corresponding tunnel portal through an anchoring device;

one end of the stiffening stay cable is anchored on the rock mass at two sides of the V-shaped trough, and the other end of the stiffening stay cable is connected with the cantilever section and is used for improving the overall stability of the combined bridge;

the stiffening steel truss is arranged at the midspan section formed by the two cantilever sections, so that the spanning capacity of the combined bridge body is improved.

The invention also provides a construction method of the single cantilever construction combined bridge for the V-shaped gullies, which comprises the following steps:

step 1, tunnel construction, namely respectively carrying out tunnel construction on two sides of a V-shaped trough, and reinforcing the edges of a bottom plate of a tunnel portal section close to the V-shaped trough;

step 2, working space excavation: respectively excavating downwards in the reinforced areas of the bottom plates of the two tunnel portal sections, and supporting a foundation pit while excavating to form a working space;

step 3, construction of a zero segment: carrying out zero-number section casting construction in the working space to form two zero-number sections on two sides of the V-shaped trough;

and 4, construction of a counterweight section: constructing a casting balance weight section at one end of each zero section far away from the V-shaped trough, and embedding an anchor rod sleeve in the casting process;

and 5, foundation construction of the anchoring device: installing a drill rod in the anchor rod sleeve at the top of the counterweight section, and downwards drilling into a rock mass bearing layer below the working space through a drilling machine to form an anchor hole; installing an anchor rod in the anchoring hole, then grouting and filling to form an anchoring device, and anchoring the counterweight section and the rock mass into a whole;

step 6, cantilever section construction: constructing cantilever sections of tunnel openings at two sides of the gullies from the zero section, and constructing the cantilever sections in sections by using hanging baskets;

step 7, stay cable construction: when the cantilever section is constructed to a span range of 2/3-1/3 of the span, constructing the cantilever section by adopting the method of step 6, and simultaneously, lagging a stage to install a tensioning stiffening stay cable, so as to ensure that the deformation of the beam body meets the linear requirement until the last cantilever section before closure;

step 8, construction of a folding section: when the two cantilever sections are constructed section by section to the folding section, one hanging basket is retreated, the other hanging basket is selected to hoist the rigid frame of the folding section, the linearity of the bridge is adjusted, and the folding section is poured to finish closure;

step 9, construction of stiffening steel trusses: after the closure section is hardened, removing a hanging basket on the bridge, and hoisting and removing the bridge deck; assembling stiffening steel trusses in situ on a bridge deck to form a monolithic whole, adjusting the cable force of the stiffening stay cable for multiple times to adjust the linearity of the bridge, and welding the stiffening steel truss sheets to anchor joints reserved on the bridge deck;

step 10, bridge deck auxiliary construction: after the bridge deck is cleaned, the auxiliary engineering construction of the bridge is completed, and the construction of the combined bridge is completed.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a single cantilever construction combined bridge for V-shaped valleys, which cancels the traditional T-shaped rigid frame bridge pier,

the construction of pouring of a bracket-free single cantilever is realized by using the counterweight and the anchoring foundation, and the diameters of two sides of the beam body are supported on the bottom plate of the tunnel, so that the problem of slope stability caused by engineering risk caused by exceeding pier construction and slope toe scouring caused by the pier occupying the valley flood-passing area is avoided. Meanwhile, a combined structure is formed by arranging stiffening stay cables, stiffening steel trusses or the combination of the stiffening stay cables and the stiffening steel trusses, the crossing capacity of a beam body is increased, the economic application range of the bridge type is enlarged to 30-300 m, the traditional prefabricated simply supported beam scheme, the T-shaped rigid frame scheme and the arch bridge scheme can be replaced, the engineering cost is low, the construction risk is low, the process improvement difficulty is low, the bridge type with competitive power in V-shaped valley landforms is provided, the types of the bridge are enriched, and the bridge type has great engineering value.

Drawings

Fig. 1 is a schematic diagram of a prior art T-shaped rigid frame bridge.

FIG. 2 is a schematic diagram of a single cantilever construction composite bridge on a V-shaped valley in an embodiment of the invention.

FIG. 3 is a construction diagram of a single cantilever construction composite bridge in an embodiment of the invention

Fig. 4.1 is a schematic diagram of tunnel construction in step 1.

Figure 4.2 working space excavation schematic in step 2.

And 4.3, constructing a zero section in the step 3.

Fig. 4.4 is a schematic diagram of construction of the counterweight segment in step 4.

Fig. 4.5 a schematic view of the construction of the anchoring device in step 5.

Fig. 4.6 is a schematic diagram of the construction of the cantilever section in step 6.

Fig. 4.7 schematic diagram of stay cable construction in step 7.

Fig. 4.8 is a schematic diagram of the construction of the closure segment in step 8.

FIG. 4.9 is a schematic view of the construction of a stiffening steel truss in step 9.

Fig. 4.10 a schematic diagram of the construction of the finished single cantilever construction composite bridge in step 10.

200-single cantilever construction combined bridge, 210-zero section, 220-counterweight section, 230-cantilever section, 240-folding section, 250-anchoring device, 251-anchor rod, 260-working space, 270-hanging basket, 300-V-shaped trough, 400-tunnel, 410-tunnel portal, 500-stiffening stay cable, 510-stay cable, 520-stay cable anchoring device and 600-stiffening steel truss.

Detailed Description

Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit the scope of the invention.

As shown in fig. 2 and 3, the present invention provides a single cantilever construction composite bridge 200 comprising a zero-numbered section 210, a counterweight section 220, a cantilever section 230, a closure section 240, a stiffening stay cable 500, and a stiffening steel truss 600;

the zero section 210 is provided with two sections, and the two sections are respectively arranged in tunnel openings 410 at two sides of the V-shaped trough 300 and are used for providing a fulcrum of a combined bridge, and the weight on the bridge is transmitted to a tunnel bottom plate through a support and then is transmitted into the ground;

the outer ends of the two cantilever sections 230 are respectively connected with the two zero sections 210, and the inner sides are connected through a folding section 240;

a counterweight section 220 is arranged on one side of each zero section 210 corresponding to the corresponding cantilever section 230, and the counterweight section 220 is anchored on the rock mass at the bottom in the corresponding tunnel portal 410 through an anchoring device 250 and is used for providing bending moment generated by the balanced cantilever section due to suspension;

one end of the stiffening stay cable 500 is anchored on the rock mass at two sides of the V-shaped trough through the stay cable anchoring device 520, and the other end is connected with the cantilever section for improving the overall stability of the combined bridge;

the stiffening steel truss 600 is arranged in the midspan section formed by the two cantilever sections, so that the spanning capacity of the combined bridge body is increased.

As a preferred embodiment, the bottom of the zero-number section 210 is provided with a support, i.e. the zero-number section 210 is mounted on the tunnel floor at the tunnel portal 410 by means of the support, and the weight of the bridge is transferred to the tunnel floor by means of the support. The zero section 210 is supported on the support, the two ends of the zero section 210 are respectively provided with a counterweight section 220 and a cantilever end, and bending moment around the support generated by the cantilever is balanced through the configuration section.

As a preferred embodiment, as shown in fig. 4.3, the support is a steel ball type support (not shown in fig. 4.3), which is located on the middle bottom plate of the zero segment 210, and vertically supported between the tunnel bottom plate and the zero segment 210, so as to ensure that the gravity of the structure is transferred to the mountain.

As a preferred embodiment, as shown in fig. 4.3, the top of the zero-numbered section 210 is flush with the tunnel floor in the tunnel portal 410 on both sides of the V-shaped trough 300.

As a preferred embodiment, as shown in fig. 2, the counterweight segment 220 is formed by a solid beam-cast prestressed concrete structure, and is integrally connected with the zero segment 210 by internal prestressed steel strands and reinforcing steel bars (prestressed bundles). Still further preferably, high density steel sand concrete casting may be used to better balance the moment generated by the cantilever segment 230; so that the whole bridge is in a mechanically stable state.

As a preferred embodiment, as shown in fig. 2, the anchoring device 250 includes a bolt 251 sleeve pre-embedded in the weight section 220, an anchoring hole formed in the rock body at the bottom of the tunnel, a bolt 251 inserted into the anchoring hole from the bolt 251 sleeve, and grouting for filling the periphery of the bolt 251 to form an anchoring structure; the grout may preferably be an epoxy mortar.

As a preferred embodiment, as shown in fig. 2, the anchor rods 251 of the anchoring device 250 are anchor rods 251, and the weight segments 220 are anchored with the mountain (the rock at the bottom of the tunnel) integrally by a plurality of anchor rods 251 penetrating through the bottom plate of the tunnel, so as to balance the unbalanced bending moment generated by the weight segments 220 and the cantilever segments 230 around the support.

As a preferred embodiment, as shown in fig. 2, the anchor 251 is inserted into the rock mass to a depth greater than the thickness or height of the weight segment 220 itself.

As a preferred embodiment, as shown in fig. 2, the cantilever segment 230 is a prestressed concrete structure, and prestressed steel strands (prestressed bundles) required by ensuring structural stress are arranged inside the cantilever segment.

As a preferred embodiment, the cantilever section 230 may be a hollow box beam, the cross-sectional type of the box beam is not limited, and the bridge cross-sectional height of the cantilever section 230 is gradually reduced from the zero-numbered sections 210 at both sides of the V-shaped valley 300 to the folding section 240 at the middle of the V-shaped valley 300.

As a preferred embodiment, the cantilever section 230 adopts the hanging basket 270 to perform the prefabricated beam sectional splicing construction or the sectional cast-in-situ construction, and the specific construction mode is not limited and is determined according to the actual working condition of the site.

As a preferred embodiment, the folding section 240 is a cast-in-situ or prefabricated box beam, which is used to connect two cantilever sections 230 extending from adjacent tunnel openings 410 of the V-shaped trough 300 into a whole, so as to form a bridge integral structure.

As a preferred embodiment, as shown in FIG. 2, the stiffening stay cable 500 is a stay cable 510 dedicated to a cable-stayed bridge in the prior art, wherein one end of the stay cable 510 is anchored in a rock body above a tunnel portal, and the other end is anchored in a span-mid-cantilever section range (i.e. two cantilever sections are close to a closure section) of the girder body, and the anchoring height of the stay cable anchoring device 520 on the stay cable 510 is selected so that the angle of the stay cable 510 is generally in the range of 30 degrees to 60 degrees. The stay cables 510 are generally arranged in a single row, a double row or three rows, the bridge deck of the beam body is respectively arranged in the middle of the bridge deck, two sides of the flange or the combination of the two sides, compared with the two-way double-lane or four-lane bridge, the bridge is not particularly wide, one row of stay cables 510 can be respectively arranged on the flanges of the two sides of the beam body, if the lanes are too large, the road surface is relatively wide, and one row of stay cables 510 can be additionally arranged in the middle of the beam body.

As shown in fig. 2, the stiffening steel truss 600 adopts a steel truss structure formed by i-steel or steel sections, is longitudinally arranged in the span range of 1/3-2/3 of the middle of the beam body, and has a height and a transverse number determined according to span mechanics calculation, and is generally arranged in a single row, a double row or three rows, wherein the bridge floor of the beam body is respectively arranged in the transverse middle, the two sides of the flange or the combination of the two sides, so that the stiffening steel truss is an auxiliary facility for increasing the stability of the beam body.

As shown in fig. 4.1 to 4.9, the present invention further provides a construction method of the single cantilever construction composite bridge 200, comprising the steps of:

step 1, constructing a tunnel 400, as shown in fig. 4.1, respectively performing tunnel construction (adopting a scheme in the prior art, such as a blasting method, a shield method and the like) on two sides of a V-shaped trough 300, and reinforcing the edges of a bottom plate of a tunnel portal section close to the V-shaped trough 300, wherein the bottom plate of the tunnel portal section can be particularly reinforced by adopting a rectangular frame;

step 2, working space 260 excavation: as shown in fig. 4.2, the foundation pit is excavated while the foundation pit is supported in the reinforced areas (i.e. in the rectangular frames) of the two tunnel portal section bottom plates respectively to form a working space 260, and the supporting mode is determined according to geological conditions, for example, steel plate supporting can be adopted;

step 3, construction of a zero segment 210: as shown in fig. 4.3, the zero-number segment 210 is cast in the working space 260 to form two zero-number segments 210 on both sides of the V-shaped valley 300; before the construction of the construction zero section 210, the inner bottom of the working space 260 is excavated in a super-deep manner, and then concrete is poured to strengthen the inner bottom of the working space 260.

The casting construction method of the zero segment 210 is as follows:

and arranging a support on the bottom plate in the working space 260 according to the drawing requirement, binding a reinforcing cage of the zero-number section 210, arranging a prestressed corrugated pipe, pouring concrete to form the zero-number section 210, and reserving an extension reinforcing bar at the end part of the zero-number section 210 when binding the reinforcing cage of the zero-number section 210.

Step 4, construction of a counterweight section 220: as shown in fig. 4.4, a casting weight section 220 is constructed at one end of each zero segment 210 far from the V-shaped gully 300, and a sleeve of anchor rod 251 is pre-buried in the casting process; the construction method of the counterweight section 220 is as follows:

binding a reinforcement cage of the counterweight section 220 in the working space 260, welding the reinforcement cage and the zero section 210 into a whole by reserving extension reinforcement, arranging hoops of the anchor rods 251 in the reinforcement cage of the counterweight section 220, and pouring concrete to form the counterweight section 220.

Preferably, steel sand concrete casting may be used to increase the weight of the weight segment 220. To improve the balance capability of the balance weight section 220 to the bending moment of the cantilever section 230, reduce the dependence of the low anchoring device 250, the anchoring capability of the anchoring device 250 depends on the geological condition under the tunnel to a great extent, when the geological condition is good, the anchoring device can provide a very good anchoring effect when being a hard rock layer, but the geological condition is not good, when the rock layer or the rock mass is loose, the effect of the anchor rod 251 is limited, and the weight of the balance weight section 220 needs to be increased to balance the bending moment of the cantilever section 230.

Step 5, foundation construction of the anchoring device 250: as shown in fig. 4.5, at the top of the weight section, a drill rod is installed in the bolt 251 casing, and the drill is drilled down into the rock mass bearing layer below the working space 260 by a drill to form an anchor hole; installing the anchor rod 251 in the anchor hole, then grouting and filling to form an anchor device 250, and anchoring the counterweight section and the rock mass into a whole;

step 6, cantilever segment 230 construction: as shown in fig. 4.6, from the zero section 210, the cantilever section 230 of the tunnel portal 410 on two sides of the valley is constructed, and the cantilever section 230 is constructed in sections by using the hanging basket 270;

step 7, construction of stay cable 510: when the cantilever section is constructed to a span range of 2/3-1/3 of the span, constructing the cantilever section by adopting a method of step 6, and simultaneously, lagging a stage to install a tensioning stiffening stay cable 500, so as to ensure that the deformation of the beam body meets the linear requirement until the last cantilever section before closure;

step 8, construction of a folding section 240: as shown in fig. 4.7, when two cantilever sections 230 are constructed to a folding section 240 section by section, one hanging basket 270 is retreated, the other hanging basket 270 is selected to hoist the rigid frame of the folding section 240, the linearity of the bridge is adjusted, and the folding section 240 is poured to finish closure;

and 9, construction of a stiffening steel truss 600: after the closure segment 240 is hardened, removing the hanging basket 270 on the bridge, and hoisting and removing the bridge deck; assembling the stiffening steel truss 600 in situ on the bridge deck to form a monolithic whole, adjusting the linearity of the bridge by adjusting the cable force of the stiffening stay cable 500 for a plurality of times, and welding the stiffening steel truss 600 sheets to the reserved anchor joints of the bridge deck;

step 10, bridge deck auxiliary construction: and as shown in fig. 4.9, after the bridge deck is cleaned, the auxiliary engineering construction of the bridge is completed.

Specifically, the bridge deck auxiliary construction comprises auxiliary structure construction such as an anti-collision wall, a cable groove, a street lamp and the like.

The above embodiments are only for illustrating the present invention, and are not limiting of the present invention. While the invention has been described in detail with reference to the embodiments, those skilled in the art will appreciate that various combinations, modifications, and substitutions can be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A construction method for a single cantilever construction composite bridge for V-shaped valleys, comprising the steps of:

step 1, tunnel construction, namely respectively carrying out tunnel construction on two sides of a V-shaped trough, and reinforcing the edges of a bottom plate of a tunnel portal section close to the V-shaped trough;

step 2, working space excavation: respectively excavating downwards in the reinforced areas of the bottom plates of the two tunnel portal sections, and supporting a foundation pit while excavating to form a working space;

step 3, construction of a zero segment: carrying out zero-number section casting construction in the working space to form two zero-number sections on two sides of the V-shaped trough;

and 4, construction of a counterweight section: constructing a casting balance weight section at one end of each zero section far away from the V-shaped trough, and embedding an anchor rod sleeve in the casting process;

and 5, foundation construction of the anchoring device: installing a drill rod in the anchor rod sleeve at the top of the counterweight section, and downwards drilling into a rock mass bearing layer below the working space through a drilling machine to form an anchor hole; installing an anchor rod in the anchoring hole, then grouting and filling to form an anchoring device, and anchoring the counterweight section and the rock mass into a whole;

step 6, cantilever section construction: constructing cantilever sections of tunnel openings at two sides of the gullies from the zero section, and constructing the cantilever sections in sections by using hanging baskets;

step 7, stay cable construction: when the cantilever section is constructed to a span range of 2/3-1/3 of the span, constructing the cantilever section by adopting the method of step 6, and simultaneously, lagging a stage to install a tensioning stiffening stay cable, so as to ensure that the deformation of the beam body meets the linear requirement until the last cantilever section before closure;

step 8, construction of a folding section: when the two cantilever sections are constructed section by section to the folding section, one hanging basket is retreated, the other hanging basket is selected to hoist the rigid frame of the folding section, the linearity of the bridge is adjusted, and the folding section is poured to finish closure;

step 9, construction of stiffening steel trusses: after the closure section is hardened, removing a hanging basket on the bridge, and hoisting and removing the bridge deck; assembling stiffening steel trusses in situ on a bridge deck to form a monolithic whole, adjusting the cable force of the stiffening stay cable for multiple times to adjust the linearity of the bridge, and welding the stiffening steel truss sheets to anchor joints reserved on the bridge deck;

step 10, bridge deck auxiliary construction: after the bridge deck is cleaned, the auxiliary engineering construction of the bridge is completed, and the construction of the combined bridge is completed.

2. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 1, wherein: in the step 1, a rectangular frame is adopted for reinforcing the bottom plate of the tunnel portal section, and a working space is excavated in the rectangular frame.

3. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 1, wherein: in the step 3, before the construction of the zero section casting construction, the inner bottom of the working space is excavated in a super-depth mode, and then concrete is cast for reinforcement, so that the inner bottom plate of the working space is formed.

4. A construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 3, wherein: in the step 3, the zero section pouring construction method comprises the following steps:

and arranging a support on the bottom plate in the working space according to the drawing requirement, binding a zero-section steel reinforcement cage, arranging a prestressed corrugated pipe, pouring concrete to form a zero-section, and reserving an extension steel bar at the end part of the zero-section when binding the zero-section steel reinforcement cage.

5. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 4, wherein: in the step 4, the construction method of the counterweight section is as follows:

binding a balance weight section steel reinforcement cage in the working space, welding the balance weight section steel reinforcement cage and the zero-number section reserved extension steel reinforcement into a whole, arranging anchor rod hoops in the balance weight section steel reinforcement cage, and pouring concrete to form the balance weight section.

6. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 5, wherein: in the step 4, the counterweight section is formed by casting steel sand concrete with high density.

7. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 5, wherein: in the step 5, the anchoring holes are filled with epoxy mortar for anchoring.

8. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 5, wherein: and (6) in the construction process of the cantilever section, a prestress beam is arranged in a roof of a beam body of the cantilever section, and the prestress beam is tensioned on the previous section after the construction of the previous section.

9. The construction method for a single cantilever construction composite bridge for V-shaped valleys according to claim 5, wherein: in the step 6, the cantilever section adopts a hollow beam with a weight reducing function, and the height of the bridge section of the cantilever section is gradually reduced from the zero section at two sides of the V-shaped trough to the folding section in the middle of the V-shaped trough.

10. A single cantilever construction combination bridge for V-arrangement trough which characterized in that: the device comprises a zero section, a counterweight section, a cantilever section and a folding section;

the number of the zero sections is two, and the zero sections are respectively arranged in tunnel openings at two sides of the V-shaped gully;

the outer ends of the two cantilever sections are respectively connected with two zero sections, and the inner sides of the two cantilever sections are connected through a folding section;

one side of each zero segment, which corresponds to the corresponding cantilever segment, is provided with a counterweight segment, and the counterweight segments are anchored on the rock mass at the bottom in the corresponding tunnel portal through an anchoring device.