Temporary Cased Flight Auger

A temporary casing can be screwed into the upper parts of the borehole normally to a maximum depth of 6.0M. The casing seals out any water ingress or provides support to loose soils in the first few metres of the drill hole.

As boring proceeds, the bore is lined with (temporary) steel casings screwed together in sections. These steel lining tubes are used to support unstable ground and exclude water from the bore. Where the bore has penetrated into clay it is often unnecessary to use lining tubes and the bore is advanced 'open hole'. On reaching the depth necessary to develop the required bearing capacity of the pile, a steel reinforcement cage is placed centrally in the pile.

Self-compacting concrete of high workability is then poured and at the same time, the steel lining is steadily withdrawn or can be left in situ. The method ensures that all weaknesses in the stratum are adequately filled with concrete and cover to the steel reinforcement is maintained.