Design and Construction Validation of Pile Performance through High Strain Pile Dynamic Tests for both Contiguous Flight Auger and Drilled Displacement Piles

Authors: S. Pirrello

Abstract:

Sydney’s booming real estate market has pushed property developers to invest in historically “no-go” areas, which were previously too expensive to develop. These areas are usually near rivers where the sites are underlain by deep alluvial and estuarine sediments. In these ground conditions, conventional bored pile techniques are often not competitive. Contiguous Flight Auger (CFA) and Drilled Displacement (DD) Piles techniques are on the other hand suitable for these ground conditions. This paper deals with the design and construction challenges encountered with these piling techniques for a series of high-rise towers in Sydney’s West. The advantages of DD over CFA piles such as reduced overall spoil with substantial cost savings and achievable rock sockets in medium strength bedrock are discussed. Design performances were assessed with PIGLET. Pile performances are validated in two stages, during constructions with the interpretation of real-time data from the piling rigs’ on-board computer data, and after construction with analyses of results from high strain pile dynamic testing (PDA). Results are then presented and discussed. High Strain testing data are presented as Case Pile Wave Analysis Program (CAPWAP) analyses.

Keywords: Contiguous flight auger, case pile wave analysis, high strain pile, drilled displacement, pile performance.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1340358

References:

[1] Australian Standard, AS2159-2009. Piling- Design and installation.
[2] Brown, D.A, 2005. Practical considerations in the selection and use of continuous flight auger and drilling displacement piles. American Society of Civil Engineers, ASCE J. Geotechnical special publication No.132, pp.1-11.
[3] Larish, M. D, 2014. Behaviour of stiff, fine-grained soil during the installation of screw auger displacement piles. PhD Thesis, The University of Queensland, Australia.
[4] Pells, P. J. N, Dougals, D. J. Rodway, B., Thorne, C., McMahon, B. K., 1978. Design loadings for foundations on shale and sandstone in the Sydney region. Australian Geomechanics J. Vol.G8, pp. 31-39.
[5] Pells, P. J. N., 1998. State of practice for design of socketed piles in rock. Proceedings of the 8th A.N.Z. Conference on Geomechanics, Hobart, pp. 307-326
[6] Randolph, M. F., 1994. RATZ load transfer analysis of axially loaded piles, program manual.
[7] Slatter, .J, 2006. Recent developments in continuous flight auger (CFA) and cast-in-situ displacement screw piling in Melbourne. Australian Geomechanics J. Vol. 41, No. 3, pp. 17-24.
[8] Van Impe, W.F., 1988. Considerations on auger pile design. Proc. of 1st 2nd Int. Conference on Deep Foundations on Bored and Augered Piles, Ghent, Balkema.
[9] Van Impe, W. F., 1994. Influence of screw pile installati.on parameters on the overall pile behaviour. Workshop ‘Piled Foundations: Full Scale Investigations, Analysis and Design’, Naples.