Axial resistance of CFA piles in Dublin boulder clay

This paper describes the results of static compression and tension load tests performed on three-instrumented large diameter Continuous Flight Auger piles installed in Dublin boulder clay. The piles developed very high shaft resistance and, in contrast to piles driven into boulder clay which exhibit friction fatigue, the shaft distribution was uniform along the pile shaft. This resulted in the normalised average shear resistance being mobilised by a bored pile exceeding that of a pile driven in similar ground conditions. In contrast the base resistance of the test piles were significantly lower than a pile driven in similar ground conditions.