ROTARY DISPLACEMENT auger piling is one of the fastest growing sectors of the foundation industry.
Usually credited as the invention of Belgian Professor Wille van Impe, it seems the concept may be much older than previously assumed.
Gerry Anderson's 1965 cult TV puppet series Thunderbirds, now being reshown on British terrestrial television, features an incredible drilling machine, the Mole. Its drilling head bears a remarkable resemblance to a rotary displacement piling auger.
However it is not wholly a case of life imitating art. According to the Thunderbirds official website, the Mole weighs 30 tons and is powered by engines supplied by fuel from an on-board nuclear reactor. It is ferried to the danger zone aboard one of the Thunderbird 2 pods and then carried by its own tracked vehicle to the drilling site.
Once at the location, the Mole is tilted for vertical drilling with its C30/1 drill bit, which can cut through any known metal or rock. Caterpillar tracks on its side propel the Mole down its own bore hole. This allows the vehicle to reverse to the surface once the rescue operation is completed.
The sinking house that hit that tabloids at Christmas is back in the news with contractor Branlows taking the limelight for putting the problem right. Within weeks ofmoving into Rose Farm at Irlam, Manchester, the Whitfield family's newly built 'dream house'started sinking, moving an incredible 1. 5m in five weeks.
Engineers from structural engineering consultancy Brian Clancy Partnership were appointed to monitor movements. They called in Warrington-based Branlows to provide foundations for an identical house to be built in front of the existing one, which is to be demolished. The original foundations were 150mm square, precast segmental piles driven into 9m ofpeat overlying very soft clay to 13m to 14m overlying dense sand. Branlows'replacement used 273mm diameter permanently cased bottom driven piles, each joint having a continuous fillet welded rigid connection.
Some 18 piles were installed to depths of 16m to17m ending in the dense underlying sands. Total cost of demolition and rebuilding work is expected to be about £200,000.