Rotary bored Pile

Rotary bored Piling uses a bored piling machine with specially designed drilling tools, buckets and grabs to remove soil and rock. The auger with 4 or 5 turns of flight is bored into the ground, withdrawn, and the spoil removed. This process is repeated until the design depth is reached.

If the surrounding ground will not stand open as the auger passes up and down, casings are used. These can be temporary or permanent. They are handled by the rig or by Cranes, depending on size and weight. Where the pile diameter or depth is so great a casing would be too long or heavy, or where groundwater would flood the bore, drilling fluid such as bentonite is used.

The advantages over CFA piling are the depths and diameters achievable. Also by using casing an open hole can be formed to great depths. This enables chiselling or coring at depth to form rock sockets, the placement of unusually long or complex reinforcement cages, or complex pile instrumentation and load cells.

Rotary bored piles deeper than 40m are common and recent trends have seen piles over 70m deep.