The main construction techniques involved in the installation of U-shaped girders include double-crane lifting, bridge erecting machine construction, modular vehicle construction, and sliding construction. This article will introduce them one by one.

1.Double-crane Lifting Construction

Double-crane lifting, which is the most commonly used construction method for hoisting rail beams, is widely used in various construction sites. Its main benefits are its versatility and convenience. It can be hoisted in different positions, such as parallel parking hoisting and T-shaped parking hoisting, and can meet the requirements of different positions during hoisting and positioning, and has strong adaptability to the transportation and positioning of U-shaped beams. The equipment is relatively simple and can be used in large quantities to shorten the construction period. Its main shortcomings are that it requires a better transport road, and the construction occupies a large site. When it is close to the existing road, this method is still feasible, but it is necessary to do a good job in protecting underground pipelines and overhead lines on the ground. If there is no existing road, a better road needs to be opened up, which costs a lot, and it is also inconvenient to cross bridges and rivers.

2. Bridge Erecting Machine Construction

Bridge erecting machine construction is also a common construction technology in rail transit construction. Its main advantages are that there is no need for a special girder transportation road, and the already erected rail beams become high-altitude beam transportation channels. The construction basically has no impact on the ground, the construction process is relatively simple, the equipment operation is repeated, and it is easy to master proficiently, and the external uncertain factors have little impact on it, and the rhythm is strong. Its main shortcomings are that the structural form of the rail beam line to be laid is relatively single, and it is also necessary to open up a beam-loading site, beam-loading equipment and beam transportation equipment, and the ability to adapt to external changes is poor. When the beam transportation is too long, the work efficiency is easily reduced. During the construction, the sequence is strong and the beam supply cannot be reversed.

3.Modular Vehicle Construction

Modular vehicle construction has basically not been applied in the rail transit construction process. The modular vehicle is a self-propelled flat trailer that is modularly manufactured and assembled, with a horizontal adjustable elevation is 600 mm (1.2 to 1.8 m). Its advantages are that it can be configured into various structures, sizes and masses according to the different needs of the loaded goods. At the same time, the traction force of the modular vehicle is provided by the hydraulic motor. Each axis performs various actions and realizes various postures such as movement, rotation, and lifting under the precise control of the main control program, and can also complete the actions that traditional trailers cannot complete, and can turn around in place, translate horizontally, and rotate around the midpoint. The drawback is that the auxiliary workload is large, additional beam-loading equipment is required, and the overall usage price is high and cannot be used in large quantities.

4. Sliding Construction

Sliding construction technology is also often applied in rail transit construction. It is divided into bracket method and cantilever method according to the support method, and is divided into friction type and wheel-rail type according to the sliding form. Generally speaking, the sliding method is generally applied in some places with extremely harsh working conditions and where large equipment cannot be used for construction, and the auxiliary workload is extremely large.

Conclusion

The construction methods that can be adopted in various working conditions are diverse and also have certain trade-offs. There is no best construction technology, only the most appropriate construction technology. Many times the difficulties of local construction also have a considerable help to the entire construction. At the same time, the enterprise's own resources also have a considerable impact on the process selection. It is hoped that this article can provide certain reference and help for the construction of U-shaped girder.