Dry boring methods make use of a temporary casing to seal the pile bore through
water-bearing or unstable strata overlying suitable stable material. Upon reaching
the design depth, a reinforcement cage is introduced; concrete is placed in the
bore and poured to the required level. The casing is then withdrawn.
‘Wet’ boring also employs a temporary casing through unstable ground and is used
when the pile bore cannot be sealed against water ingress. Boring is then undertaken
using segmental augers/ digging buckets to drill/dig through the underlying soils
to design depth. The reinforcement cage is lowered into the bore and concrete is
placed by tremmie pipe to displace the water which is present in the bore, following
which, extraction of the temporary casing takes place.