Modelling of Influence of Matric Suction Induced by Native Vegetation on Ground Behaviour
Speaker:Dr. Behzad FATAHI
Senior Lecturer of Geotechnical and Railway Engineering,
Centre for Built Infrastructure Research (CBIR),
University of Technology Sydney (UTS), Sydney, Australia
Date & Time:23 Jun 2014 (Monday) 15:00 - 16:00
Venue:J215 (University of Macau)
Organized by:Department of Civil and Environmental Engineering

Abstract

Bioengineering including native vegetation is an ancient method of improving the stability of slopes. In modern railway engineering, this technique is re-captured for increasing the soil stiffness and shear strength of sub-grade beneath rail tracks. Tree roots provide three stabilising functions: (a) reinforcement of the soil, (b) dissipation of excess pore pressures and (c) establishing sufficient matric suction to increase the shear strength.The main focus of this presentation will on investigating the effects of vegetation on soil matric suction, ground settlement and lateral movement (radial consolidation). A mathematical model developed for the rate of root water uptake based on the root growth rate and considering ground conditions, type of vegetation and climatic parameters, is presented. A two dimensional finite element approach based on ABAQUS has been employed to solve the transient coupled flow and deformation equations incoporating the proposed root water uptake model as a subroutine. To validate the model, an array of field measurements conducted at Miram site in Victoria, Australia are presented. In addition, the action of two rows of trees on improving the soil behaviour under railway or road embanklments are compared to a vertical drain with applied suction (vacuum pressure).

Biography

Dr. Fatahi has worked as a consulting and site geotechnical and railway engineer and has completed doctorate studies in Soft Soil Geomechanics from the University of Wollongong in Australia. He was a part of very strong geotechnical design teams in several alliance projects around Australia mainly on road and highway construction/upgrade and was involved in forensic and confidential projects for mining sector in Australia while working in Coffey International (Sydney Office). He worked as a full-time researcher for Rail-CRC conducting research to improve performance of rail tracks built on soft soils to minimise the maintenance costs. Behzad has immensely contributed to the idea of green corridors for railway lines. Dr. Fatahi was named 'Australasia Young Railway Engineer of Year 2007' by Engineers Australia and Railway Technical Society of Australasia. Behzad was also awarded the first prize at the Young Geotechnical Professional's Night in 2006, which is a prestigious geomechanics award from the Australian Geomechanics Society and Engineers Australia. He is currently a senior lecturer of Geotechnical and Railway Engineering at the University of Technology Sydney (UTS) leading several large research projects funded by the Australian Research Council and key engineering companies in the field of soft soil engineering and ground improvement, and supervising numerous PhD students.