A steel-concrete composite arch bridge spanning a karst cave in a tunnel and a construction method thereof

Abstract

The present invention provides a steel-concrete composite arch bridge across a cave in a tunnel and a construction method thereof, wherein the arch bridge comprises a plurality of steel arch ribs arranged in parallel, the two ends of each steel arch rib are fixedly connected to arch seats cast on the two side walls of the cave, there is a certain spacing between adjacent steel arch ribs, and they are connected by a plurality of cross beams, a supporting steel plate is laid on the cross beam, a layer of concrete arch ribs is cast on the top of the steel plate support and the steel arch ribs, a concrete filling layer is cast on the top of the concrete arch ribs, and the top surface of the concrete filling layer is flush with the bottom surface of the tunnel. During construction, the steel arch ribs are first installed by vertical rotation construction, and then the steel arch ribs are used as brackets to construct the upper concrete arch ribs, making full use of the characteristics of the steel arch ribs, such as small dead weight, high strength, and convenient and quick installation, avoiding the need to set up a formwork bracket under the bridge, thereby reducing the construction difficulty, ensuring the construction quality, reducing safety risks, and reducing construction costs.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and relates to a steel-concrete composite arch bridge structure and a construction method thereof, which is used for crossing a karst cave when a karst cave is encountered during tunnel excavation. Background Art

[0002] When encountering caves during tunnel excavation, backfilling is generally used for smaller caves, while bridges can be used to cross larger caves. However, for large and deep caves, the efficiency of bridge construction is low due to the small space in the tunnel, where large machinery cannot function properly. Especially for water-crossing caves, there are also problems such as difficulty in setting up formwork supports under the bridge, making it difficult to construct bridges in caves. Summary of the invention

[0003] The purpose of the present invention is to provide a steel-concrete composite arch bridge structure and a construction method for crossing a large karst cave in a tunnel in order to solve the problem of difficulty in crossing a large karst cave during tunnel construction, thereby reducing construction difficulty and improving construction efficiency.

[0004] The present invention provides a steel-concrete composite arch bridge that spans a cave in a tunnel, which is characterized by comprising a plurality of steel arch ribs arranged in parallel, both ends of each steel arch rib being fixedly connected to arch seats cast on the two side walls of the cave, a certain spacing between adjacent steel arch ribs, and being connected by a plurality of cross beams, support steel plates being laid on the cross beams, a layer of concrete arch ribs being cast on the top of the steel plate supports and the steel arch ribs, a concrete filling layer being cast on the top of the concrete arch ribs, and the top surface of the concrete filling layer being flush with the bottom surface of the tunnel.

[0005] The present invention provides a method for constructing a steel-concrete composite arch bridge across a karst cave in a tunnel, which is characterized by comprising the following steps:

[0006] (1) Cast two opposing arch seats on the two side walls of the cave, one of which is provided with a hinged support, and the other is provided with a pre-embedded section of a steel arch rib;

[0007] (2) Bend multiple I-beams into arc-shaped arch ribs, and set the span of the arch ribs according to the distance between the two arch seats; connect 2-3 arch ribs into a group using cross beams;

[0008] (3) Using a truck crane, lift a group of arch ribs to the top of the arch seat where the hinged support is set, and connect one end of each arch rib to the arch seat through a swivel hinge;

[0009] (4) A fixed pulley is installed at a certain height on the side wall of the cave above the arch seat, and a cable is passed around the fixed pulley and connected to the other end of the arch rib;

[0010] (5) Slowly loosen the cable to allow the arch rib to rotate toward the arch seat on the other side of the cave under the action of gravity;

[0011] (6) After the arch rib is vertically rotated into place, the hinged end of the arch rib and the arch seat is fixed, and the other end of the arch rib is welded to the embedded section of the arch rib on the other arch seat;

[0012] (7) According to the above method, each group of arch ribs is installed and fixed on the arch seat in sequence, and each group of arch ribs is connected into a whole with a cross beam, and then a patterned steel plate is welded on the upper part of the cross beam;

[0013] (8) Use the steel arch rib and the steel plate welded to the beam as the formwork support, and pour a layer of concrete arch rib on the upper part;

[0014] (9) After the concrete arch rib reaches the designed strength, a concrete filling layer is poured on top of it until it is flush with the bottom surface of the tunnel.

[0015] The present invention adopts steel sections as arch ribs to span the cave according to the topographic conditions at the cave and the characteristics of the bridge span structure. During construction, the steel section arch ribs are first installed in groups through the vertical rotation construction process, which solves the difficulty of large-scale mechanical equipment in the tunnel. Then, the steel section arch ribs are used as supports to construct the upper concrete arch ribs. After the construction is completed, the steel section arch ribs and the concrete arch ribs form a steel-concrete composite arch structure to jointly bear the upper load, and the characteristics of the steel section arch ribs, such as small dead weight, high strength, and convenient and quick installation, are fully utilized, and the erection of formwork supports under the bridge is avoided, thereby reducing the construction difficulty, ensuring the construction quality, reducing safety risks, and reducing construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side structural schematic diagram of the steel-concrete composite arch of the present invention;

[0017] Figure 2 It is a schematic diagram of the elevation structure of the steel-concrete composite arch;

[0018] Figure 3 yes Figure 2 A magnified view of the local structure in

[0019] Figure 4 It is a schematic diagram of the plan structure of the steel arch rib;

[0020] Figure 5 This is a schematic diagram of the state of using a truck crane to hoist the steel arch rib;

[0021] Figure 6 It is a schematic diagram of the vertical rotation state of the steel arch rib;

[0022] Figure 7 This is a schematic diagram of the completed installation of the steel arch rib across the cave. DETAILED DESCRIPTION

[0023] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the steel-concrete composite arch bridge across the karst cave in the tunnel provided by the present invention comprises a plurality of steel arch ribs 1 arranged in parallel, both ends of each steel arch rib 1 are fixedly connected to arch seats 3 cast on the two side walls of the karst cave 2, there is a certain spacing between adjacent steel arch ribs, and they are connected by a plurality of cross beams 4, support steel plates 5 are laid on the cross beams 4, a layer of concrete arch ribs 6 are cast on the top of the support steel plates 5 and the steel arch ribs, a concrete filling layer 7 is cast on the top of the concrete arch ribs 6, and the top surface of the concrete filling layer 7 is flush with the bottom surface of the tunnel 8.

[0024] In the specific implementation of the present invention, the steel arch rib 1 can be formed by bending an I-beam, and two connecting plates 9 are symmetrically welded on both sides of the web of the I-beam at a certain interval. The two ends of each crossbeam 4 are respectively connected to the two connecting plates 9 facing each other on the two adjacent arch ribs by bolts.

[0025] The specific construction method of the steel-concrete composite arch bridge across the cave in the above-mentioned tunnel is as follows:

[0026] (1) Figure 5 As shown, two opposite abutments 3 are cast on the two side walls of the cave 2, one of which is provided with a hinged support 31, and the other is provided with a steel arch rib embedded section 32;

[0027] (2) bending a plurality of I-beams into arc-shaped arch ribs 1, wherein the span of the arch ribs is set according to the distance between the two arch seats; and connecting 2-3 arch ribs into a group by using a cross beam;

[0028] (3) Using a truck crane 10, lift a group of arch ribs to the top of an arch seat 3 on which a hinged support is provided, and connect one end of each arch rib 1 to the arch seat 3 through a swivel hinge;

[0029] (4) Figure 6 As shown, a fixed pulley 11 is installed at a certain height on the side wall of the cave above the arch seat hinged to the arch rib, and a cable 12 is passed around the fixed pulley and connected to the other end of the arch rib 1;

[0030] (5) Slowly loosen the buckle cable 12, so that the arch rib rotates toward the arch seat on the other side of the cave under the action of gravity;

[0031] (6) Figure 7 As shown, after the arch rib is vertically rotated into position, the hinged support between the arch rib and the arch seat is sealed, and the other end of the arch rib 1 is welded to the arch rib embedded section 32 on another arch seat 3;

[0032] (7) According to the above method, each group of arch ribs is installed and fixed on the arch seat in sequence, and each group of arch ribs is connected into a whole with a cross beam, and then a supporting steel plate is welded on the upper part of the cross beam;

[0033] (8) Use the steel arch rib and the supporting steel plate welded on the beam as the formwork support, and pour a layer of concrete arch rib on the upper part;

[0034] (9) After the concrete arch rib reaches the designed strength, a concrete filling layer is poured on top of it until it is flush with the bottom surface of the tunnel, and then the upper tunnel structure is constructed.

Claims

1. A method for constructing a steel-concrete composite arch bridge across a karst cave in a tunnel, characterized in that: The following steps are involved: (1) Cast two opposing arch seats on the two side walls of the cave, one of which is provided with a hinged support, and the other is provided with a pre-embedded section of a steel arch rib; (2) Bend multiple I-beams into arc-shaped arch ribs, and set the span of the arch ribs according to the distance between the two arch seats; connect 2-3 arch ribs into a group using cross beams; (3) Using a truck crane, lift a group of arch ribs to the top of the arch seat where the hinged support is set, and connect one end of each arch rib to the arch seat through a swivel hinge; (4) A fixed pulley is installed at a certain height on the side wall of the cave above the arch seat, and a cable is passed around the fixed pulley and connected to the other end of the arch rib; (5) Slowly loosen the cable to allow the arch rib to rotate toward the arch seat on the other side of the cave under the action of gravity; (6) After the arch rib is vertically rotated into place, the hinged end of the arch rib and the arch seat is fixed, and the other end of the arch rib is welded to the embedded section of the arch rib on the other arch seat; (7) According to the above method, each group of arch ribs is installed and fixed on the arch seat in sequence, and each group of arch ribs is connected into a whole with a cross beam, and then a patterned steel plate is welded on the upper part of the cross beam; (8) Use the steel arch rib and the steel plate welded to the beam as the formwork support, and pour a layer of concrete arch rib on the upper part; (9) After the concrete arch rib reaches the designed strength, a concrete filling layer is poured on top of it until it is flush with the bottom surface of the tunnel.

Images