Geoscience Reference
In-Depth Information
CHAPTER 12
SEISMIC DESIGN OF PILE FOUNDATIONS FOR LIQUEFACTION EFFECTS
Ross W. Boulanger
1
, Dongdong Chang
1
, Scott J Brandenberg
2
, Richard J Armstrong
1
,
and Bruce L.Kutter
1
1. Department of Civil and Environmental Engineering, University of California
at Davis, California, USA
2. Department of Civil and Environmental Engineering, University of California
at Los Angeles, California, USA
Abstract.
Procedures for the seismic design of pile foundations for liquefaction effects are pre-
sented with emphasis on the conditions relevant to bridges. Two local subsystems for a bridge are
discussed in detail: (1) pile groups in laterally spreading ground away from the abutments and
(2) pile groups at the abutments where the restraining or “pinning” effects of the piles and bridge
superstructurecanbeadvantageous.Therecommendeddesignproceduresinvolveequivalentstatic
analyses using beam on nonlinear Winkler foundation models. Guidance for these design proce-
dures was derived from a combination of dynamic centrifuge model tests and associated nonlinear
dynamic finite element studies. The design procedures, their basis, and other issues for design of
bridges for liquefaction effects are discussed.
1. Introduction
The seismic performance and design of pile foundations in areas of liquefaction and lat-
eral spreading have been studied extensively in recent years, leading to an improved
understanding of fundamental mechanisms and associated advances in analysis and
designmethodologies(e.g.,BoulangerandTokimatsu,2006).Designproceduresforliq-
uefaction conditions using a variety of beam on soil spring models have been proposed
witharangeofrecommendationsregardingparameterselectionsandloadingdetails(e.g.,
Tokimatsu and Asaka, 1998; Martin et al., 2002; Boulanger et al., 2003; Dobry et al.,
2003; Tokimatsu, 2003; Liyanapathirana and Poulos, 2005; Rollins et al., 2005; Cubri-
novski and Ishihara, 2006; Brandenberg et al., 2007a). Some of the differences in rec-
ommended parameter relationships and loading conditions are important to practice and
warrant furtherstudy to resolve.
This paper presents guidance on the seismic design of pile foundations for liquefaction
effects, with a specific focus on conditions relevant to bridges. Two situations, as illus-
trated in Figure 12.1, are described: (1) pile groups in laterally spreading ground where
the out-of-plane thickness of the spreading ground is sufficiently large that free-field soil
displacements are relatively unaffected by the presence of the pile groups and (2) pile
groups at approach embankments where the restraining or “pinning” effects of the piles
andbridgesuperstructurecanreducethelateralspreadingdemandsimposedbythefinite-
width embankment. Guidance for both situations is limited to equivalent static analyses
