The ALPACA research project to improve design of piles driven in chalk

Abstract

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.