How Does Bridge Jacking Work?

Bridge Jacking is the activity wherein the various structural points or parts of a bridge are slowly lifted and then put out to help repair and replace these parts. The process of bridge jacking is also widely known as the structural lifting process or operation. This structural lifting is necessary to ensure that the structural components of the bridge’s integrity are maintained as the activity of repairing and replacement on the bridge is being done. One of the main aspects to keep in mind about the bridge shoring activity is that during this process, the parts of the bridge that need repair are not removed but are simply given additional support to the bridge’s structure until the process is completed.

The main difference between the process of bridge shoring and bridge jacking is that during shoring, bridges can support live load, but this is not possible during jacking. The process of both jacking and shoring are equally important for repairs and replacements of parts of bridges in various situations. The many parts of bridges that take the help of shoring and jacking for repairs are beams, piers, girders.

What is the importance of bridge jacking?

The process of bridge jacking is important for the repairs and replacements activities to take place. With the help of bridge jacking, the load of the entire structure of the bridge is relieved, and it helps in repairing the components and parts of the bridge that are already present, and the process will easily be in full effect.

During the process of bridge jacking, the activity of hydraulic systems is most typically used to stress cables, replace the bearings and beams and even in replacing trusses and the process of jacking is mainly used for total replacements in a bridge.

The rigging process is also attached to this process and is particularly used in the process of inspection. As bridge jacking is mostly used for full bridge replacement, the old bridge whose structure is failing is removed, and the new, improved structure is placed in its place. The activities of bridge jacking and bridge shoring are essential and are done by professional engineers to achieve optimum results.

Types of Jacks

Hydraulic –

The most widely used and conventional technique or machine for jacking is hydraulic jacks. These jacks are always available in a wide range of volumes, with the limit of up to 1000 tones. Furnished with a turn head, they can oblige slight misalignment of the jacking surface and ensuing rotational development of the design. You can also opt for 300 ton hydraulic cylinder for inspections.a

An implicit locking collar permits the water driven framework to be taken out once compression is finished and gets the jack against unexpected development and obstruction. In cases of extension bearing substitution, Freyssinet plan and assembling PTFE and elastomer sliding surfaces, which enable the jack head to oblige restricted vertical and flat underlying development, for example, to permit connect deck jacking under live traffic.

Flat Jacks: 

Similar to hydraulics, flat jacks are available in a large number of volumes up to 1000 tones and can be put to use for various situations that can be either temporary or permanent. A flat jack machine consists of two plates made out of steel and conjoins at the rim.

When it is inflated, the machines work so that the two steel plates, upper and lower, are pushed apart and can produce forces up to 15 N/mm2. Therefore, these machines can easily work in places with a gap for jacking is 50mm or even less. During temporary situations when there is an option to remove the jack, inflation occurs using hydraulic oil. In a permanent jack situation that can be such as bearing pre-loading or just structural lifting, the flat jack can be put up from the outset with epoxy resin, or it can be started with hydraulic oil and then mixed with under load using epoxy resin later.

Considerations

Various things need to be kept in mind before the process of bridge jacking can be processed. Many issues are to be considered and may take place which can happen:

  • The structure of the bridge might get affected and lead to failure.
  • The articulation and working of the present bearing as compared to the original or last one.
  • The movement and working of the deck about support.
  • Monitoring of all the parts and members.
  • The functionality and appropriateness of the new design and structure.
  • The stage at which the corrosion might be taking place and will ultimately lead to repairs and replacements.

Conclusion

Bridge shoring is one of the essential methods used by expert engineers to achieve all the infrastructure repairs. This helps to ensure that all the repairs and replacements properly and execute all the plans correctly. You can also replace trusses, bearings, beams, and other stressing cables within the Hydraulic systems.

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