Editors’ Note

Abstract

This issue addresses a timely and broad array of pile-related subjects ranging from battered piles in embankments, seismic behaviour of helical piles, cased and uncased drilled shaft behaviour as well as the performance of soil nails for slope stabilisation. Jehu Johnson and his co-authors present the results of numerical simulations of T-walls supported by battered piles within levee embankments. This research resulted, in part, from the heightened awareness of the performance of levee embankments after the failures associated with Hurricane Katrina in New Orleans, Louisiana. The authors performed an extensive amount of numerical two dimensional finitedifference simulations to investigate the effects of various parameters on Settlement-Induced Bending Moment T-walls with batter piles. A specific focus of the study addressed the effect of structural head fixity and associated moment loading. The authors identified a linear relationship between the batter angle and pile bending moment for the conditions and range of batter angles investigated and a reduction of pile bending moment for pile batters when aligning closer to vertical. Qiang Li, Armin Stuedlein, and Tony Marinucci compare the performance of side resistances for drilled shafts with and without casing using four full-scale, instrumented drilled shafts. Such data are vital given the great importance in quantifying the impact of construction techniques during design. The authors utilise data from thermal integrity profiler sensors to interpret the differences in soil-shaft contact conditions and the resulting load transfer. The uncased test shafts exhibited significantly greater axial shaft resistance compared to the cased test shafts. Important performance metrics between the cased and uncased shafts, including the axial load–displacement curves, load transfer distributions, and back-calculated unit shaft resistance–relative displacement relationships (t–z curves) are presented in full detail. Alireza Askari and Arash Gholami conduct 3D numerical parametric studies to investigate the effects of soil nail length and orientation on various segments of a slope. Parametric variations include the slope height and the surcharge pressure. The authors provide recommendations for optimising the nail geometry in the upper, middle and lower parts of the slope and show under which angular orientation the maximum performance can be expected. Amy Cerato, Tatjana Vargas and Shawn Allred close this issue with an in-depth review of the state-of-knowledge on the seismic behaviour of helical piles. Given the growing application of helical piles, Dr Cerato’s paper is well timed to provide needed assistance to designers. This work is part of a three phase investigation on the use of helical piles for earthquake mitigation and identifies future research needs in the light of seismic retrofit requirements. The results of an extensive literature and industry search for previous seismic tests performed on helical piles are described as well as the current design standards used in seismic regions. This work was funded, in part, by through DFI’s technical committee projects and is endorsed by the DFI Helical Pile Committee. We hope you will enjoy this issue and encourage you to join our lineup of authors that consistently contribute meaningful and practice-oriented research and case histories to enhance the geotechnical profession.