ARC Centre of Excellence Geotechnical Science & Engineering

RHD Students

Firman Raybat Siahaan

RHD Students


BEng (Hons), MEngSc


  • 2010
    Master of Engineering Science in Geotechnical Engineering and Engineering Geology, at the University of NSW, Australia
  • 2006
    Bachelor of Engineering (Hons) in Civil Engineering at the University of NSW, Australia


  • 2006
    Summer Research Scholar, UNSW, Australia, 4 months
  • 2006
    Geotechnical Engineer, Coffey Geotechnics, Sydney, Australia, 6 years (ongoing)

Research Interests

  • Soft Soil Improvements
  • Foundation Engineering
  • Micromechanics in Geomechanics


  • Professor Buddhima Indraratna
  • Dr Cholachat Rujikiatkamjorn

Research Topic

Micromechanically-Inspired Stone Column Behaviour in Soft Soil Improvement

Research Abstract

This project investigates behavior of a stone column used in soft soil improvement from the micromechanical perspective. As a granular assembly, shear resistance and boundary dilation of stone column are influenced by particle morphological properties such as shape, roundness and roughness. The first part of this project attempts to derive mathematical representation that correlates the basic micromechanical parameters, such as inter-particle friction angle and angularity, with the shear strength and lateral strain internally and in the vicinity of boundary. Column clogging due to clay/silt contamination and particle breakage will be accordingly considered. Subsequently, the composite behavior of stone column and clay under the embankment loading is studied by applying Constant Normal Stiffness (CNS) condition at the column-clay interface and considering the limiting yield stress of clay. Through this project, it is expected that proper understanding on behavior of single stone column is gained and extendable to include the behavior of column groups for the improvement of soft clay.