Chalk is present under large areas of NW Europe as a
low
-
density, porous
,
weak carbonate rock.
Large numbers
of
offshore wind turbines, bridge
s
and port facilities rely on piles driven in chalk.
C
urrent
European practice assume
s
ultimate shaft resistances that appear low
in
comparison with the Chalk’s unconf
ined
compression strength and CPT cone resistance ranges
and
can impact very significantly on project economics.
L
ittle guidance is available on pile driveability, set
-
up or lateral resistance in chalk, or on how piles driven in
chalk can sustain
axial or
lateral
cyclic loading. This paper describes the ALPACA (Axial
-
Lateral Pile Analysis
for Chalk Applying multi
-
scale field and laboratory testing)
p
roject
funded by EPSRC and Industry
that is
develop
ing
new design guidance through comprehensive field testin
g at
a
well
-
characterised low
-
to
-
medium
density test site
,
supported by analysis of
other
te
sts.
Field experiments on
36
driven piles,
sixteen
of
which
employ
high resolution fibre
-
optic strain gauges,
is
supported by advanced laboratory and in
-
situ testing, as well
as theoretical analysis. The
field work commenced in October
2017 and
was largely complete in
May
2019.