Slope Stabilizing Piles and Pile-Groups: Parametric Study and Design Insights
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 7
Abstract
This paper uses a hybrid method for analysis and design of slope stabilizing piles that was developed in a preceding paper by the writers. The aim of this paper is to derive insights about the factors influencing the response of piles and pile-groups. Axis-to-axis pile spacing (), thickness of stable soil mass (), depth () of pile embedment, pile diameter (), and pile group configuration are the parameters addressed in the study. It is shown that is the most cost-effective pile spacing, because it is the largest spacing that can still generate soil arching between the piles. Soil inhomogeneity (in terms of shear stiffness) was found to be unimportant, because the response is primarily affected by the strength of the unstable soil layer. For relatively small pile embedments, pile response is dominated by rigid-body rotation without substantial flexural distortion: the short pile mode of failure. In these cases, the structural capacity of the pile cannot be exploited, and the design will not be economical. The critical embedment depth to achieve fixity conditions at the base of the pile is found to range from to , depending on the relative strength of the unstable ground compared to that of the stable ground (i.e., the soil below the sliding plane). An example of dimensionless design charts is presented for piles embedded in rock. Results are presented for two characteristic slenderness ratios and several pile spacings. Single piles are concluded to be generally inadequate for stabilizing deep landslides, although capped pile-groups invoking framing action may offer an efficient solution.
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Acknowledgments
This work was partially supported by the EU 7th Framework research project funded through the European Research Council’s (ERC) “Ideas” Programme, in support of Frontier Research—Advanced Grant Contract No. UNSPECIFIEDERC-2008-AdG 228254-DARE.
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© 2011 American Society of Civil Engineers.
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Received: Dec 30, 2009
Accepted: Nov 1, 2010
Published online: Nov 4, 2010
Published in print: Jul 1, 2011
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