Evaluating Proposed Solutions for Equivalent Plane Strain Modeling of PVD
Assisted Preloading
Ali Parsa-Pajouh
1
, Behzad Fatahi
2
, Hadi Khabbaz
3
, and Philippe Vincent
4
1
PhD Candidate, School of Civil and Environmental Engineering, University of Technology Sydney
(UTS). E-mail: Ali.ParsaPajouh@uts.edu.au
2
Senior Lecturer in Geotechnical Engineering (PhD, CPEng), School of Civil and Environmental
Engineering, University of Technology Sydney (UTS). E-mail: behzad.fatahi@uts.edu.au
3
Associate Professor in Geotechnical Engineering (PhD), School of Civil and Environmental
Engineering, University of Technology Sydney (UTS). E-mail: hadi.khabbaz@uts.edu.au
4
Technical Manager, Menard Bachy Pty Ltd. Email: pvincent@menardbachy.com.au
ABSTRACT: In this study, a numerical code has been developed using FLAC 2D to
model the prefabricated vertical drain (PVD) assisted preloading process considering
the smear zone, and evaluate the efficiency of the proposed equations for the
conversion of permeability coefficient from axisymmetric state to plane-strain
condition. A laboratory PVD assisted preloading test has been conducted employing a
fully instrumented large Rowe cell to verify the developed numerical code. The results
of the numerical plane-strain and axisymmetric simulations have been compared using
four methods of permeability conversion from axisymmetric to plane-strain condition.
INTRODUCTION
Barron (1948) introduced the first axisymmetric classical solution to estimate the
radial PVD assisted consolidation including the effect of the smear zone properties,
namely the extent ratio (the smear zone radius over the drain radius, r
s
/r
w
), and the
permeability ratio (the permeability of the intact zone over the permeability of the
smear zone, k
h
/k
s
). A number of solutions were developed to improve Barron’s (1948)
theory for radial axisymmetric consolidation (e.g. Hansbo, 1981; Onoue, 1988).
Considering the available mathematical developments and to save computation time, it
is possible to conduct the numerical simulation of the multiple vertical drains or
complex tree root system using 2D numerical analysis adopting the equivalent plane-
strain permeability for the intact region and the smear zone (Indraratna et al., 2005;
Fatahi et al, 2009 and 2010). Several methods have been proposed for the conversion
of the permeability from axisymmetric state to plane-strain condition (e.g. Hird et al.,
1992; Lin et al., 2000; Tuan and Mitachia, 2008). In this study, a numerical code has
been developed to evaluate the accuracy of different permeability conversion methods
9 Advances in Transportation Geotechnics and Materials for Sustainable
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