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Pipe jacking is a technique for installing underground pipelines, ducts and culverts. Powerful hydraulic jacks are used to push specially designed pipes through the ground behind a shield at the same time as excavation is taking place within the shield. A thrust wall is constructed to provide a reaction against which to jack. In poor ground, piling or other special arrangements may have to be employed to increase the reaction capability of the thrust wall. Where there is insufficient depth to construct a normal thrust wall, for example through embankments, the jacking reaction must be resisted by means of a structural framework having adequate restraint provided by means of piles, ground anchors or other such methods for transferring horizontal loads.
Construction on the new cylindrical and circular reservoir at the Vlakfontein Reservoir, Benoni
The construction of a 210ML Reservoir project kicked off in 2020.
Esor Construction was sub-contracted to instal concrete sleeves by means of pipejacking method for the steel piping connecting the new 210ML reservoir to the existing reservoir and to install a 660m overflow pipeline also by means of pipejacking.
Linking the old with the new.
Three jacked sleeves connecting the older reservoir to the new Mega reservoir varied in size and length. It comprised in jacking 2 x2.5m diameter sleeves and total length of 45m long and one 2,25m diameter with a length of 22m long.
Normal jacking setups are constructed in an excavated pit to allow the thrust to bear against a concrete wall spreading the load onto the immediate in-situ material.
In this case there were no jacking pit and, the concrete thrust wall had to be constructed protruding the “N.G.L” with the capability to withstand the jacking forces.
Overflow pipeline
For the 660m long overflow pipeline a 1800diameter jacked concrete sleeve was required.
Eight intermediate jacking stations was established to an average of 8,5m deep with jacking distances of up to 114m between them.
In some of the jacking stations we had to jack in opposite directions. One line was completed, the setup turned to continue jacking in a different direction.
Contract Value : R 14 980 552.85
Completion : July 2022
