CN101736685A - Ground-anchored-self-anchored suspension combined system bridge - Google Patents

Abstract

The ground anchor-self-anchor suspension composite system bridge belongs to the technical field of construction engineering, and particularly relates to the design of long-span bridges under complex geological conditions in bridge engineering. Its characteristics are: after the construction of the cable tower and the side hole pier, the cantilever assembly of the concrete main beam of the cable-stayed bridge begins; after the cantilever is assembled to the side hole, the main cable is suspended, and one end is anchored on the permanent anchor block, and the other end is anchored on the outer end of the concrete beam. The anchor block is pulled on the temporary anchorage with temporary anchor cables; the beam end of the main girder with permanent anchor block is supported horizontally on the abutment; the steel girder in each section of the mid-span is hoisted by a cable crane; after closing, Temporary anchor cables are removed in batches, and the main cable is completely anchored at the end of the main girder, completing the system conversion from temporary anchorage to self-anchor. The effect and benefit of the present invention are that the performance of the material is fully utilized, and for complex geological conditions, huge anchorages are saved, the project cost is reduced, the construction period is shortened, and the risk in the construction process is reduced.

Description

Ground anchor-self-anchored suspension-stayed combined system bridge

technical field

The invention belongs to the technical field of construction engineering and relates to the design of bridges in bridge engineering, in particular to the design of long-span bridges.

Background technique

At present, the following types of bridges are usually used in the design of long-span bridges:

1. Cable-stayed bridge

The cable-stayed bridge with the largest span that has been built now is the Tatara Bridge in Japan, with a span of 890m. However, when the cantilever span of the cable-stayed bridge reaches about 500m during construction, its aerodynamic stability is really worrying. At the same time, its axial horizontal pressure will increase rapidly with the increase of the cantilever span. Buckling instability will occur near the tower.

2. Suspension Bridge

The suspension bridge with the largest span is the Akashi Kaikyo Bridge in Japan, with a main span of 1991m. However, the amount of steel used for the main cable and girder of the suspension bridge is large, which increases the construction cost. At the same time, the long-span suspension bridges are all anchored in the ground, requiring huge anchorage, and their volume increases rapidly with the increase of the span. According to reports, the cost of a suspension bridge with a main span of 1000m is 16.7% higher than that of a cable-stayed bridge with the same span. In addition, aerodynamic stability is also a restrictive factor for the development of suspension bridges with large spans.

3. Cable-stayed-suspension collaborative system bridge

This type of bridge adopts a cable-stayed structure for the side span and a suspension cable structure for the mid-span, giving full play to the respective advantages of the cable-stayed bridge and the suspension bridge. The first bridge of this type in the world - Guizhou Wujiang Bridge was built in China, with a main span of only 288m. Many domestic and foreign sea-crossing bridges, such as the Lingdingyang Bridge and the Bering Strait Bridge, have proposed this scheme. At present, the bridge type is mainly in the scheme design stage. The proposed schemes are all ground anchor systems, which require huge anchors, are difficult to construct, and cost high.

Contents of the invention

The technical problem to be solved by the present invention is to propose a long-span bridge design scheme for complex geological conditions.

The technical solution of the present invention is to first construct the cable-stayed bridge part, and then hang the main cable, one end of the main cable is anchored to the permanent tunnel anchor, and the other end is anchored to the temporary anchor block, and then the steel main girder of the suspension bridge part is hoisted. After closing, remove the temporary anchor cable, complete the conversion of the main cable system, and adopt the ground anchor-self-anchor system. Concrete beams are used for the cable-stayed section, and steel beams are used for the mid-span suspension section.

Specific steps:

Step 1: After the construction of the cable tower and the side hole pier, start the cantilever assembly of the concrete main girder of the cable-stayed bridge;

Step 2: After the cantilever is assembled to the side hole, the main cable is suspended, one end is anchored on the permanent anchor block, the other end is anchored on the outer end anchor block of the concrete beam, and the anchor block is pulled on the temporary anchor by a temporary anchor cable;

Step 3: The beam end of the main girder with permanent anchor blocks is horizontally supported on the abutment;

Step 4: Use a cable crane to hoist the steel girders of each section of the mid-span;

Step 5: After closing, the temporary anchor cables are removed in batches, the main cable is completely anchored at the end of the main beam, and the system conversion from temporary anchorage to self-anchor is completed;

Step 6: Complete bridge deck pavement, railing construction, and adjust the cable force of the whole bridge to complete the bridge.

Effect and benefit of the present invention are:

1. Adopt the combination system of ground anchor and self-anchor, adopt permanent ground anchor system on the side with good geological conditions, and the main beam is also supported on the mountain on this side, and use self-anchor system on the side with poor geological conditions. This bridge type is adapted to local conditions and is economically reasonable;

2. The use of self-anchoring system saves huge anchorage, not only reduces the cost, but also shortens the construction period;

3. The load of the cable-stayed bridge part is transmitted to the tower foundation through the bridge tower, unlike in the suspension bridge, this part of the load is transmitted to the tower foundation through the main cable, which reduces the diameter of the main cable and saves materials;

4. During the construction process, the cantilever of the cable-stayed bridge is shortened, and the range of the suspension bridge is also reduced after the completion of the bridge. Therefore, the aerodynamic stability during the construction process and after the completion of the bridge has been significantly improved, reducing the risk during the construction process ;

5. The part of the cable-stayed bridge is shortened, and the axial pressure at the root of the main beam near the tower is reduced. While ensuring the stability of the main beam, it can also reduce the area of the concrete main beam and reduce the construction cost;

6. Concrete girders are used in the cable-stayed bridge section, while steel girders are used in the suspension bridge section to give full play to the material properties and greatly save the cost.

Description of drawings

Figure 1 is a schematic diagram of the temporary anchorage of the ground anchor-self-anchor suspension system bridge.

In the figure: 1 main cable; 2 main beam; 3 suspender; 4 stay cable; 5 main tower; 6 tunnel anchor; 7 side pier.

Figure 2 is a schematic diagram of the bridge completion scheme of the ground anchor-self-anchor suspension system.

In the figure: 1 main cable; 2 main beam; 3 suspender; 4 stay cable; 5 main tower; 6 tunnel anchor; 8 anchor block.

Detailed ways

The specific implementation manner of the present invention will be described in detail below in combination with the technical scheme and accompanying drawings.

After the main girder of the cable-stayed bridge is assembled in place, the main cable is suspended. One end of the main cable is anchored to the permanent tunnel anchor, and the other end is anchored to the temporary anchor block. The intermediate steel box girder is hoisted, and after the main girder is closed, the temporary anchor cables are removed to complete the conversion of the main cable system, and then the cable force of the whole bridge is adjusted.

Main girder section: part of the main girder of the cable-stayed bridge adopts the concrete box girder section, and the part of the suspension bridge adopts the steel box girder section.

Material properties: C50 concrete is used for part of the main girder and wet joints of the cable-stayed bridge, and C30 concrete is used for pier piles; Q345 steel is used for part of the main girder of the suspension bridge. the

Load class: Highway-I class.

Material characteristics of stay cables and main cables: Stay cables and main cables are twisted cables with extruded sheath.

Claims (1)

1. earth anchor-from anchor hangs and draws combined system birdge, and by the co-operative system that cable stayed bridge and suspension bridge constitute, stiff girder adopts self-anchoring system along bridge to the good end of geological conditions, and an end of geological conditions difference adopts the earth anchor system, it is characterized in that:

1) after the construction of Sarasota and lateral opening pier, beginning free cantilever erection cable stayed bridge concrete girder;

2) free cantilever erection hangs main push-towing rope after lateral opening finishing, and an end is anchored on the permanent anchor block, and the other end is anchored on the anchor block of concrete beam outer end, and anchor block is pulled on the interim anchorage with interim anchor cable;

3) be provided with the girder beam-ends of permanent anchor block, horizontal support is on abutment;

4) with each section of cable crane lifting span centre steel girder;

5) close up after, remove interim anchor cable in batches, the complete anchor of main push-towing rope is in the girder end, finishes by interim anchorage to the system conversion from anchor.

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