Methods for dismantling steel arch frames used in the construction of box-type reinforced concrete arch bridges

Abstract

This invention relates to a method for dismantling steel arch frames used in the construction of box-type reinforced concrete arch bridges. The steel arch frame is divided into one arch crown segment, two arch waist segments, and two arch foot segments. Two winches are installed on each side of the arch crown segment on the bridge, and one anchor tower is installed on each bank. Two transverse beams are inserted across the bridge at both ends of the arch crown segment. One transverse beam is inserted in each arch waist and arch foot segment. The transverse beams in the arch crown segment are securely connected to the winches on both sides of the bridge, and the transverse beams in the arch waist and arch foot segments are securely connected to the anchor towers on both banks using steel strands. First, the arch crown segment is lowered onto a transport ship using the winches. Then, the arch waist and arch foot segments are rotated vertically downwards as a whole. The left arch waist segment is supported on the transport ship, and the arch waist segment is dismantled. Finally, the arch foot segments are rotated vertically onto the transport ship, and the arch foot segments are dismantled. This invention provides high efficiency and safety in arch frame dismantling and avoids damage to the bridge structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bridge construction, and relates to a combined dismantling method of a steel arch frame for box-type reinforced concrete arch bridge construction. BACKGROUND

[0002] The box-type reinforced concrete arch bridge has good stress performance, economy and durability, and is a bridge type widely used for crossing special geological environments such as mountain gorges and rivers. During the construction of the box-type reinforced concrete arch bridge, a steel arch frame is often used as a supporting structure for installing a formwork and bearing a concrete pouring construction load of the arch bridge. After the construction of the arch bridge is completed, the arch frame needs to be dismantled.

[0003] The steel arch frame is often composed of multiple pieces of a Bailey beam spliced in segments. During installation, the steel arch frame can be hoisted by using a cable-stayed buckle hanging method or a cable crane, which is similar to the installation construction of arch ribs of the arch bridge. However, during the dismantling of the steel arch frame, the constructed arch bridge blocks the way, and the construction space under the bridge is limited, so that large equipment cannot be used for dismantling. Generally, only small segments of the steel arch frame can be dismantled piece by piece, which is low in efficiency and poor in safety.

[0004] In the prior art, patent CN210684485U discloses a steel arch frame dismantling device for construction of a deck-type box-type arch bridge. A plurality of hangers are pre-buried in the concrete of the arch bridge to be connected with the steel arch frame, and a plurality of hanger holes are reserved on the bridge. The steel arch frame is dismantled in segments. When each segment is dismantled, a winch is arranged on the bridge to be connected with the segment through a hanger, and then the connection between the segment and the hanger and other segments is released. The segment is lowered to a transport ship below by the winch.

[0005] The above device can realize the dismantling of large segments of the steel arch frame. However, a large number of hangers reserved in the concrete of the arch bridge need to be cut off and the concrete needs to be repaired in the later period. The cutting and repairing operations are performed by workers in a hanging basket, which not only increases the workload, but also has a certain danger in high-altitude construction. In addition, a part of the steel hangers is left in the concrete, which easily forms a corrosion channel and causes diseases such as concrete cracking. SUMMARY

[0006] The purpose of the present application is to provide a dismantling method of a steel arch frame for box-type reinforced concrete arch bridge construction, which can ensure the safety of the dismantling construction of the arch frame, improve the construction efficiency, and avoid damaging the concrete structure of the arch bridge.

[0007] The technical scheme of the present application is as follows:

[0008] A dismantling method of a steel arch frame for box-type reinforced concrete arch bridge construction, the box-type reinforced concrete arch bridge being a river-crossing arch bridge, characterized in that the method comprises the following steps:

[0009] (1) divide the steel arch into five large segments, including one arch top segment, two arch waist segments and two arch foot segments; after the arch bridge construction is completed, two winches are arranged on the bridge opposite to the two sides of the arch top segment, and one tower is arranged on each bank;

[0010] Two beams are arranged across the bridge at the two ends of the arch top segment, and one beam is arranged in each arch waist segment and arch foot segment near the front end, and each beam protrudes to the outside of the two sides of the bridge; the two ends of each beam arranged in the arch top segment are connected firmly with the winches on the two sides of the bridge through steel strands; the two ends of the beams arranged in the arch waist segment and the arch foot segment are connected firmly with the tension jacks on the towers on the two banks through steel strands;

[0011] (2) the transport ship is driven to the position directly below the arch top segment; the connection between the arch top segment and the two arch waist segments of the steel arch is released, and the arch top segment is lowered to the transport ship through the winch;

[0012] (3) after the transport ship transports the arch top segment to the designated position and returns, it is driven to the position below the arch waist segment on the left side of the steel arch; the tension jacks on the left tower are loosened to make the steel strands relax, and the left arch waist segment and the arch foot segment are vertically turned downward as a whole until the left arch waist segment is supported on the transport ship;

[0013] the connection between the left arch waist segment and the tower is released, and then the connection between the left arch waist segment and the arch foot segment is released, so that the arch waist segment is completely released onto the transport ship;

[0014] (4) the tension jacks on the left tower are tensioned to make the steel strands tensioned, and the arch foot segment is vertically turned upward by a certain angle; after the transport ship transports the left arch waist segment to the designated position and returns, it is driven to the position below the left arch foot segment; the tension jacks on the left tower are loosened to make the steel strands relax, and the left arch foot segment is vertically turned downward until the left arch foot segment is supported on the transport ship;

[0015] the connection between the left arch foot segment and the arch base and the connection between the left arch foot segment and the tower are released, so that the left arch foot segment is completely released onto the transport ship, and the transport ship transports the left arch foot segment to the designated position;

[0016] (5) the right arch waist segment and the arch foot segment are removed by the same method, and the whole steel arch is removed.

[0017] The present application uses the cable-stayed and hanging method, the vertical turning method and the large segment lifting method in the installation of the steel structure arch rib as the reverse process of the above-mentioned methods, and combines the above-mentioned methods to remove the steel arch, so that the large segment removal of the steel arch under the condition of limited space is realized, the construction efficiency and safety are improved, and the damage to the bridge structure is avoided.

[0018] The present application is especially suitable for the dismantling construction of the steel arch frame installed by the inclined cable fastening and hanging method or the vertical turning method, the fastening tower is not dismantled temporarily after the installation of the steel arch frame, and is used in the later arch frame dismantling, so that the arch frame dismantling construction cost can be saved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the construction flow chart of the present application;

[0020] Figure 2 is the side view of the present application for fixing the arch frame segment by the cross beam and the steel strand before the arch frame dismantling;

[0021] Figure 3 is the plan view of the present application for fixing the arch frame segment by the cross beam and the steel strand;

[0022] Figure 4 is Figure 3 is the partial enlarged view of the steel arch frame fixing structure;

[0023] Figure 5 is the state schematic view of the whole arch top segment being lowered to the ship by the winch;

[0024] Figure 6 is the state schematic view of the arch waist segment and the arch foot segment on one side of the arch frame being vertically turned downward by the fastening tower;

[0025] Figure 7 is the dismantling state schematic view of the arch foot segment;

[0026] Figure 8 is the state schematic view of the steel arch frame after the dismantling. DETAILED DESCRIPTION

[0027] Figure 1 is the construction flow chart of the present application, and the specific construction mode is as follows:

[0028] (1) as shown in Figure 2 , Figure 3 , Figure 4 , the steel arch frame is divided into five large segments before the arch frame dismantling, including one arch top segment 1, two arch waist segments 2 and two arch foot segments 3; after the construction of the arch bridge 100, two winches 4 are arranged on the bridge opposite to the two sides of the arch top segment, one fastening tower 5 is arranged on the two banks, and a tensioning jack is arranged on the fastening tower;

[0029] the fastening tower structure is the same as the fastening tower structure for installing the arch rib by the inclined cable fastening and hanging method; if the steel arch frame is installed by the inclined cable fastening and hanging method or the vertical turning method, the fastening tower is not dismantled after the installation of the arch frame, and is used as the fastening tower 5 in the above-mentioned arch frame dismantling;

[0030] Two beams 6 are respectively arranged at two ends of the crown segment 1 in the transverse direction, one beam 6 is arranged in each of the haunch segment 2 and the spring segment 3 near the front end, and each beam 6 protrudes to the outside of the two sides of the bridge at two ends; the two ends of each beam 6 arranged in the crown segment 1 are respectively connected to the winch 4 on the two sides of the bridge through the steel strand; the two ends of the beam 6 arranged in the haunch segment 2 and the spring segment 3 are respectively connected to the tensioning jack on the buckle tower 5 on the two banks through the steel strand 7;

[0031] (2) As shown in Figure 5 , the transport ship 200 is driven to be below the crown segment 1 of the bridge, and a support for supporting the arch segment is arranged on the transport ship in advance; the connection between the crown segment 1 of the steel arch and the two haunch segments 2 is released, and the crown segment 1 is lowered onto the transport ship 200 through the winch 4;

[0032] (3) As shown in Figure 6 , the transport ship 200 transports the crown segment to the designated position and returns, and is driven to be below the haunch segment on the left side of the steel arch; the tensioning jack on the left buckle tower 5 loosens the steel strand, and the left haunch segment 2 and the spring segment 3 are vertically turned downward as a whole until the left haunch segment 2 is supported on the transport ship 200;

[0033] The connection between the steel strand of the left haunch segment 2 and the buckle tower is released, and then the connection between the left haunch segment and the spring segment is released, and the haunch segment 2 is completely released onto the transport ship;

[0034] (4) As shown in Figure 7 , the tensioning jack on the left buckle tower 5 tensions the steel strand 7, and the spring segment 3 is vertically turned upward by a certain angle; the transport ship 200 transports the left haunch segment to the designated position and returns, and is driven to be below the left spring segment 3; the tensioning jack on the left buckle tower 5 loosens the steel strand 7, and the left spring segment 3 is vertically turned downward until the left spring segment 3 is supported on the transport ship;

[0035] The hinge connection between the left spring segment and the arch base and the steel strand connection between the left spring segment and the buckle tower are released, and the left spring segment 3 is completely released onto the transport ship 200, and the transport ship transports the left spring segment to the designated position;

[0036] (5) The right haunch segment and the spring segment are removed by the same method, as shown in Figure 8 , the whole steel arch is removed.

Claims

1. A method for removing a steel arch frame for construction of a box-type reinforced concrete arch bridge, the box-type reinforced concrete arch bridge being a river-crossing arch bridge, characterized by, The method comprises the following steps: (1) dividing the steel arch into five large segments, including one arch top segment, two arch waist segments and two arch foot segments; after the arch bridge is constructed, two winches are arranged on the bridge opposite to the two sides of the arch top segment, and one clamping tower is arranged on each bank; two cross beams are arranged at the two ends of the arch top segment in the cross direction, and one cross beam is arranged in each arch waist segment and arch foot segment near the front end, and each cross beam protrudes to the outside of the two sides of the bridge at the two ends; the two ends of each cross beam arranged in the arch top segment are connected to the two winches on the two sides of the bridge by steel strands; the two ends of the cross beams arranged in the arch waist segment and the arch foot segment are connected to the tensioning jacks on the clamping towers on the two banks by steel strands; (2) the transport ship is driven to the position directly below the arch top segment of the steel arch; the connection between the arch top segment and the two arch waist segments is released, and the arch top segment is lowered to the transport ship by the winch; (3) after the transport ship transports the arch top segment to the designated position and returns, the transport ship is driven to the position below the left arch waist segment of the steel arch; the tensioning jacks on the left clamping tower loosen the steel strands, and the left arch waist segment and the arch foot segment are vertically rotated downward until the left arch waist segment is supported on the transport ship; the connection between the left arch waist segment and the clamping tower is released, and then the connection between the left arch waist segment and the arch foot segment is released, so that the arch waist segment is completely released onto the transport ship; (4) the tensioning jacks on the left clamping tower tension the steel strands, and the arch foot segment is vertically rotated upward by a certain angle; after the transport ship transports the left arch waist segment to the designated position and returns, the transport ship is driven to the position below the left arch foot segment; the tensioning jacks on the left clamping tower loosen the steel strands, and the left arch foot segment is vertically rotated downward until the left arch foot segment is supported on the transport ship; the hinge connection between the left arch foot segment and the arch base and the connection between the left arch foot segment and the clamping tower are released, so that the left arch foot segment is completely released onto the transport ship, and the transport ship transports the left arch foot segment to the designated position; (5) the right arch waist segment and the arch foot segment are removed by the same method, and the whole steel arch is removed.

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