Page 1 Installation Effect of Controlled Modulus Columns on Nearby Existing Structures Huu Hung Nguyen 1 , Hadi Khabbaz 2 , Behzad Fatahi 3 , Roger Santos 4 , Michael Marix-Evans 5 , and Philippe Vincent 6 1 PhD Student, Centre for Built Infrastructure Research, University of Technology Sydney (UTS), NSW, Australia; HuuHung.Nguyen@uts.edu.au 2 Associate Professor, Centre for Built Infrastructure Research, University of Technology Sydney (UTS), NSW, Australia; Hadi.Khabbaz@uts.edu.au 3 Senior Lecturer, Centre for Built Infrastructure Research, University of Technology Sydney (UTS), NSW, Australia; Behzad.Fatahi@uts.edu.au 4 Senior Project Engineer, Fulton Hogan Australia Pty Ltd, Australia; Roger.Santos @fultonhogan.com.au 5 Design Manager, Fulton Hogan Australia Pty Ltd, Australia; Michael.Marix- Evans@fultonhogan.com.au 6 General Manager, Menard Bachy Pty Ltd, Australia; PVincent@menardbachy.com.au ABSTRACT: Controlled Modulus Columns (CMC) ground improvement technique is a novel approach to reduce ground settlement. To install CMC, a rotary displacement auger is used to form a vertical cylindrical cavity, by displacing the surrounding soils laterally, followed by grout injection. While the method reduces spoil generation, excessive lateral soil displacement may damage the adjacent structures and freshly-grouted CMCs. Although there has been growing interest in quantifying such effects, only a handful of studies have been attempted. This paper presents results of a numerical investigation on the CMC installation effect on an existing bridge pile using the three-dimensional finite difference software package FLAC 3D . The bridge pile response to the lateral soil movement induced by the CMC installation are presented and discussed. INTRODUCTION Ground improvement using Controlled Modulus Column (CMC) is an innovative method that uses rigid inclusions to reinforce soft ground, typically for projects having a tight construction schedule or concern related to contaminated soils. The Gerringong Upgrade project is one recent project where CMC have been successfully utilised for bridge and road construction (Fulton Hogan 2013). The solution consists of installing non-reinforced concrete columns in the ground, followed by the construction of a load transfer platform prior to the construction of the fill