Pipe Jacking

THIS TRENCHLESS TECHNIQUE IS USED TO INSTALL OPEN PIPELINES (STEEL, CONCRETE, GRES, PRFV, POLYCRETE) RANGING BETWEEN 100 mm AND 3000 mm IN DIAMETER. HYDRAULIC JACKS LOCATED AT THE TUNNEL ENTRY ARE USED TO PUSH IN SEQUENCED PIPE ELEMENTS TO FORM THE LINE.

A temporary (suitably sized) thrust wall is constructed to provide a reaction against the jacks.

Jacking equipment depends on the type of soil, on the diameter and length of the pipeline and also on the site-specific geological conditions.

The pipe-ground friction is a major factor since it may have an influence on the maximum length of the stretch and on the use of intermediate jacking stations.

Two different methods can be used:

1. SOIL DISPLACEMENT JACKING TECHNIQUE

Pipes are jacked without any ground removal. However, when the jacking operation involves cohesive soils and/or small-diameter pipes, the pipe front end may get stuck; in such a case the installation continues with soil displacement (as with the installation of a close-end pipe). If this is not the case, the ground will be removed from the pipeline internal upon completion of the jacking process.

2. MANUAL JACKING TECHNIQUE

For larger pipe diameters, manual mechanical excavation is required, which is controlled by the excavation front from inside the tunnel. Spoil is removed by trailers, conveyor belts, etc..

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