FROM THE DIRECTOR'S DESK
By Scott Sloan
This is the first email newsletter for the ARC Centre of Excellence for Geotechnical Science and Engineering (CGSE), which is focused on the development of cost-effective strategies for the geotechnical design of energy and transport infrastructure.
The CGSE harnesses the research strengths of the Priority Research Centre for Geotechnical and Materials Modelling at The University of Newcastle, the Centre for Offshore Foundation Systems at The University of Western Australia, and the Centre for Geotechnics and Railway Engineering at the University of Wollongong. In addition, it includes two world-renowned partner investigators in Professor Harry Poulos from Coffey Geotechnics and Professor Vaughan Griffiths from the Colorado School of Mines, and receives valuable financial support from Coffey Geotechnics, Douglas Partners, and Advanced Geomechanics.
The newsletter will augment the detailed Annual Report, which is widely distributed in April every year. Its main function is to inform the wider community of the work being done in the Centre, with a special focus on new scientific developments and their practical application.
Laureate Professor Scott Sloan.
AUSTRALIA'S FIRST NATIONAL FACILITY FOR SOFT SOILS TESTING
Richard Kelly, who is on an industry sabbatical from Coffey Geotechnics with the ARC Centre of Excellence for Geotechnical Science and Engineering, describes the development of Australia’s first national facility for testing the behaviour of soft soils. The article appeared in Engineers Australia, Volume 85, June 2013.
Physical infrastructure – such as offshore platforms and pipelines, roads and rail – is increasingly being built on extremely soft sediments. Offshore, these are encountered in almost all modern developments, where water depths now mostly exceed 500m. Onshore, transport corridors must increasingly make use of poor ground that has proved problematic for other developments. In all such cases the response of the geomaterials is complex and highly variable, and presents major design and construction challenges.
A national geotechnical soft soil field testing facility has been established near Ballina, NSW for the purpose of reducing cost and risk of infrastructure construction on low-strength, poor-quality ground onshore and offshore soft soils.
The facility is being operated by the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering (CGSE) which is a collaboration between the universities of Newcastle, Wollongong and Western Australia as well as industry partners Advanced Geomechanics, Coffey Geotechnics and Douglas Partners.
Construction of Ballina Bypass.
The need for a national soft soil field testing facility was first identified by the Ballina Bypass Alliance (BBA). The alliance, comprised of NSW Roads and Maritime Services (RMS), Leighton Contractors, Aecom, Coffey Geotechnics and SMEC, constructed the Ballina Bypass motorway over deep deposits of soft estuarine clay. During construction settlements up to 6.5m have been recorded. In contrast, target post construction settlements over 40 years ranged from 50mm to 200mm. Significant challenges were encountered in accurately characterising the properties of the soft clay, in design of extensive ground improvement solutions, in construction, and in communicating risks and opportunities with respect to whole-of-life performance of pavements and structures.
Ground improvement solutions included prefabricated vertical drains with surcharge, stability berms and structural geofabric, vibro-replacement stone columns, dry soil mixing, vacuum consolidation, dynamic replacement columns and timber piles. Lightweight bottom ash fill was also placed at various locations.
One of the goals of the alliance was to provide a legacy to the engineering community. Given the challenges encountered in this project, the idea of using surplus land owned by RMS for a field testing facility was developed. During this period the CGSE was awarded a $15 million grant over seven years to perform research in this area. The field test facility was incorporated into the CGSE to allow laboratory trials and theoretical developments to be proven in the field prior to adoption in practice.
The CGSE has four geotechnical science themes, each of which is linked to advanced computational modelling, state-of-the-art physical and laboratory testing, and engineering applications.
Research into geomaterials will include formulation of new models for highly compressible soft soils, as found on seabeds and in estuarine deposits, as well as development of novel ground improvement methods.
Multiphysics modelling will tackle emerging geotechnical design problems that span material behaviour beyond the domain of conventional soil mechanics. Examples include submarine slides, where geomaterials with high water content may transform into non-Newtonian fluids, and torpedo anchors, where the frictional strength of soil-structure interfaces varies by an order of magnitude with loading rate and accumulated displacement.
Many new infrastructure applications require an entirely new design paradigm which will allow the geostructure to move large distances during its design life. New analytical methods will allow realistic simulations of a wide range of geostructures, including offshore and onshore foundation systems, compressible earth structures and undersea pipelines. These methods also have applications for improving interpretation of in situ soil penetrometer test data.
In response to industry and community demands, the modelling and management of geotechnical risk has become a major issue in the design of all forms of physical infrastructure. This is a very challenging aspect for government authorities and engineering practice, due to the natural variability in geological deposits and the complexity of the problems that need to be analysed. Key areas of innovation will include the development of new stochastic limit and shakedown analysis techniques to predict the load capacity of geostructures under static and cyclic loads, the prediction of landslides and their effect on onshore and seabed infrastructure, such as pipelines, and risk-based prediction of slope stability including the modelling of rockfall events. This work will lead to adoption of probabilistic design methods and use of probabilistic methods when developing construction specifications and acceptance criteria for geomaterials. Communication of risk to asset owners and constructors will be based on calculation as well as engineering judgement.
A state-of-the-art soil characterisation will be followed by construction of embankments leading to an international numerical prediction competition for embankment deformations. The aim is to improve local practices in site characterisation, provide a definitive reference data set for local practice, and develop new methods of analysis and approaches to construction leading to reductions in cost, time and risk for projects.
Laureate Professor Scott Sloan is director of the 100-strong GCSE. Other chief investigators are Prof John Carter, Prof Mark Cassidy (deputy director), Prof Christophe Gaudin, Prof Buddhima Indraratna, A/Prof Kristian Krabbenhoft, Prof Andrei Lyamin, Prof Mark Randolph, Prof Daichao Sheng, and Prof David White. Partner investigators are Prof Harry Poulos (Coffey Geotechnics), Prof Vaughan Griffiths (Colorado School of Mines) and Dr Richard Merifield (SMEC). Other significant contributors working on the field test site are Dr Cholachat Rujiatkamjorn and Dr Geng Xu.
PRESTIGIOUS FELLOWSHIP FOR MARK CASSIDY
Professor Mark Cassidy, Deputy Director of the ARC Centre of Excellence for Geotechnical Science and Engineering, has been awarded a prestigious Australian Laureate Fellowship from the ARC. It is one of only 17 Laureate Fellowships awarded in 2013, and he is the only recipient based in Western Australia. Professor Cassidy is a leading researcher whose work has helped make offshore oil and gas platforms safer and more stable. This brings the number of Laureate Fellows in the Centre of Excellence for Geotechnical Science & Engineering to two, with Laureate Professor Scott Sloan being the other.
Mark’s Fellowship – worth more than $3 million – is for the project 'New Frontiers in Offshore Geotechnics: Securing Australia’s Energy Future'. The inaugural Australian Research Council (ARC) Future Fellow is also the Director of the Centre for Offshore Foundation Systems at UWA and in 2011 was appointed as a member of the ARC College of Experts for Engineering, Mathematics and Informatics. Mark made the following comments: "Offshore gas lies at the heart of Australia’s prosperity with $120 billion of infrastructure under construction. But the future of offshore gas requires new technology to safely build offshore foundations in our weak and problematic soils. This project will provide engineers with science-based tools to unlock the natural gas stranded in our deep oceans."
Laureate Professor Mark Cassidy.
Mark’s research interests are in offshore geotechnics and engineering, predominantly developing wave-structure-soil interaction models for the analysis of oil and gas platforms, mobile drilling rigs and pipelines. He is a Fellow of the Australian Academy of Technological Sciences and Engineering and has received numerous other distinctions including being named the Prime Minister's Malcolm McIntosh Australian Physical Scientist of the Year and winning the WA Premier's Early Career Achievement Award for excellence in science education, research and achievement. The ARC’s Laureate Fellowship scheme supports excellence in research at Australian universities by attracting world-class researchers and research leaders to key positions. Further information and a full list of awardees can be found here.
FUTURE FELLOWSHIP FOR ANDREI LYAMIN
Professor Andrei Lyamin has been awarded $766,856 for an Australian Research Council Future Fellowship entitled 'Variational Multiscale Modelling of Granular Materials'.
Granular materials play an important role in a wide range of problems related to physical infrastructure. These include landslides and similar catastrophic events which can result in a loss of life and major property damage. This project will develop new methods for improved simulation of granular flows to allow the formulation of efficient risk mitigation strategies. Application of the new methods to assess risk will lead to more cost-effective designs of civil infrastructure in risk prone areas, as well as better safety outcomes.
Professor Lyamin is a Chief Investigator in the Centre and is based at the Newcastle Node.
Associate Professor Andrei Lyamin.
CGSE'S UWA RESEARCHERS WIN GAS TECHNOLOGY INNOVATION AWARDS
Researchers from The University of Western Australia node, the Centre for Offshore Foundation Systems and the School of Civil and Resource Engineering swept the board in the Australian Gas Technology Innovation Awards, held last month at the AGT Conference. In the pre-commercial category, two UWA entries could not be separated by the judges and were announced as joint winners.
The first winner was UWA's O-Tube Program, which is developing new methods for the design of subsea pipelines, accounting for ocean-pipeline-seabed interaction. O-Tube Research Team Leader Professor Cheng said he was delighted to accept the award.
"The O-Tube program is developing new methods for the design of subsea pipelines. It is globally unique and allows the seabed conditions during cyclones to be mimicked on a large-scale in the laboratory," Professor Cheng said.
Gas Technology Innovation Award Winners.
Congratulations to the O-tube team: Liang Cheng, David White, Hongwei An, Scott Draper, Tuarn Brown, Chengcai Luo, Qin Zhang, Henning Mohr and Alex Duff. This is the fourth award scooped by the O-tube since it began operations three years ago.
The second winner was UWA's Remote Intelligent Geotechnical Seabed Survey technology (RIGSS). UWA's Shell EMI Chair of Offshore Engineering, Professor David White, explained that RIGSS involved a new approach to seabed characterisation.
"We are developing better tools that include our hemiball and toroidal penetrometers, and new technology derived from our centrifuge facilities to control these tools robotically at the seabed. It allows our engineers to determine the behaviour of pipelines and other infrastructure on soft, fine-grained seabeds," he said.
The O-Tube at UWA.
Congratulations to the RIGSS team: David White, David Russell-Cargill, Yue Yan, Sam Stanier, Conleth O'loughlin and Mark Randolph. A new Joint Industry Project is planned around this technology.
MANBY PRIZE AWARDED TO MAJID NAZEM, JOHN CARTER, DAVID AIREY AND SHIAOHUEY CHOW
Dr Majid Nazem, Professor John Carter, Professor David Airey and Dr Shiaohuey Chow received the Manby Prize from the Institution of Civil Engineers, London for their paper entitled "Dynamic analysis of a smooth penetrometer free-falling into uniform clay" which was published in volume 62 of Géotechnique in 2012. Dr Shiaohuey Chow is now employed as a Research Associate within the CGSE and is based at The University of Western Australia. Link to the Publication.
RAIL INNOVATION SMART TOOL DEVELOPED BY BUDDHIMA INDRARATNA
Professor Buddhima Indraratna, a Chief Investigator and node-leader in the CGSE and the Director of the Centre for Geomechanics and Railway Engineering at the University of Wollongong, has developed a SMART tool for railway track design as part of his work in the CRC for Rail Innovation. This work is being expanded and developed further by Buddhima and his team as part of a CGSE project.
The Systematic Method of Analysis for Railway Track (SMART) tool has excellent predictive and analytical capabilities for all track elements, with the potential to reduce construction costs while ensuring the highest levels of track performance under all conditions (including track fouling and geogrid use). The SMART tool is applicable to the construction of new track, the improvement of existing track maintenance procedures, and the elimination of rail inefficiencies.
High impact and cyclic loads on railway lines can cause significant track deformations leading to poor track geometry as well as a breakdown of the physical integrity of the supporting ballast. Regular impact loads at crossings, switches and insulating joints often cause rapid densification and degradation of the ballast, and also lead to and noise and vibration problems.
Professor Buddhima Indraratna.
The repeated transfer of impact loads from the wheels to the rail, and then through to the sleepers into the ballast ultimately affects the strength of the subgrade. Often these repeated impacts cause liquefaction (eg. clay pumping) and subsequent fouling of the ballast. The intrusion of fine coal dust from freight trains similarly destroys the stability of ballast formations.
The SMART tool has features which support traditional methods and add to the practical design repertoire.
VICE-CHANCELLOR'S AWARD FOR RESEARCH PARTNERSHIP
Professor Buddhima Indraratna, Associate Professor Cholachat Rujikiatkamjorn and Dr Geng Xueyu from the Wollongong node of the CGSE, in partnership with Dr Richard Kelly and Dr Jay Amaratunga of Coffey Geotechnics, have won the University of Wollongong Vice-Chancellor's Award for Research Partnership with Industry.
The Wollongong geotechnical research team, under the leadership of Professor Buddhima Indraratna, has collaborated extensively with Coffey Geotechnics on various ARC Linkage projects associated with ground improvement, including the application of vertical drains and vacuum consolidation for the development of transport infrastructure on soft soils.
This research partnership has led to tangible results including improved delivery of services and new design techniques, numerous high-calibre journal articles, and invited keynote lectures at leading geotechnical conferences.
Installation of prefabricated vertical drains.
The research outcomes have been incorporated in new Australian Standard on the "Execution of Vertical Drains in Soft Soils" launched in February 2012, led by Dr Jay Amaratunga. The techniques developed in this research have been tested in the field and applied to Port of Brisbane reclamation, the Ballina Bypass, and the rail track upgrade at Sandgate (near Newcastle).
ISMGE AND AGS AWARDS FOR CHOLACHAT RUJIKIATKAMJORN
Dr Cholachat Rujikiatkamjorn has won a Young Member Award from the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE). Competition for this particular award is always keen with dozens of candidates nominated from many nations. The award is given every 4 years and will be presented to him at the next ISSMGE Conference which will be held in Paris in September 2013.
Cholachat was also recently awarded the prestigious Trollope Medal from the Australian Geomechanics Society (AGS). The Trollope Medal is awarded to the author of an outstanding paper on either theoretical or applied geomechanics. The work reported in the paper must have been undertaken in Australia by an author under 35 years of age.
RAILWAY TECHNICAL SOCIETY POSTGRADUATE THESIS PRIZE
Dr Ngog Trung No was the runner-up for the Railway Technical Society of Australia Post Graduate Thesis Award. This comprised a $5,000 cash prize for his thesis entitled ‘Performance of Geotextile Stabilised Fouled Ballast in Rail Tracks’.
Professor Griffiths completed his Masters degree at UC Berkeley and holds a Doctoral degree from the University of Manchester, U.K. He is currently Professor of Civil Engineering at the Colorado School of Mines where his primary research interests lie in application of finite element and risk assessment methodologies to a broad range of geotechnical engineering topics. He was previously on the Civil Engineering faculty at the University of Manchester, UK and has held visiting appointments at Princeton University, the University of Sydney and the University of Canterbury, New Zealand. He has written over 250 research papers and is the co-author of four textbooks: 'Programming the Finite Element Method', 4th edition, Wiley (2004), 'Numerical Methods for Engineers', 2nd edition, Chapman & Hall/CRC (2006), 'Risk Assessment in Geotechnical Engineering' Wiley (2008) and a recently published text entitled 'Programming the Finite Element Method, 5th Edition' (download the flyer). He gives regular short-courses for ASCE Continuing Education on 'Risk Assessment in Geotechnical Engineering' and 'Finite Elements in Geotechnical Engineering'. He is on the Board of Direction of the ASCE and currently serves as an Editor of Computers and Geotechnics. Professor Griffiths is a licensed Professional Engineer in Colorado and a Chartered Engineer in the U.K.
On another note, Professor Griffiths' paper 'Slope stability analysis by finite elements', co-authored by P A Lane, (1999) has just been announced as one of Géotechnique's five 'Most Cited Papers of all time'.
PROFESSOR DAVID MUIR-WOOD TO VISIT THE CGSE
Professor David Muir-Wood, Geotechnical Engineering, School of Engineering, Physics and Mathematics at the University of Dundee, UK will be visiting the Centre in 2013. Professor Muir-Wood will spend a week at Newcastle node during October and will then travel onto UWA node where he will spend 6 weeks collaborating with research staff. Professor Muir-Wood will also attend the Centre workshop during December.
PAUL W. MAYNE WORKSHOP ON GEOCHARACTERIZATION IN THE YEAR 2013 AND BEYOND
Professor Paul W. Mayne, an internationally renowned researcher from Georgia Tech who focuses on in situ testing, delivered a one-day workshop on enhanced in situ testing with emphasis on CPT and its derivatives CPTu and SCPTu at The University of Newcastle in June 2013. The workshop was very well attended with approximately 25 staff and students from the Newcastle and Wollongong nodes, as well as 20 engineers from geotechnical practice.
PROFESSOR JOSE MUNOZ COLLABORATES WITH THE CGSE
Professor Jose Munoz studied mechanical engineering at the Universitat Politècnica de Catalunya, Spain. After gaining some professional experience in civil engineering he completed his PhD at Imperial College London, and followed this with post-doctoral studies at King's College London. He then joined the research group Laboratory de Càclul Numèric (LaCaN, www.lacan.upc.edu) at UPC, where he is now an associate professor in applied mathematics.
Joes’s current research interests are in numerical methods for limit analysis, mainly in mesh adaptivity for upper and lower bounds and more recently in decomposition methods. He is also collaborating with biological laboratories in developing numerical models for simulating soft biological tissues and cell rheology, by using cell-centered models for cell softening and hardening. Previous research works are also focused on finite element methods for embryogenesis, contact mechanics of solids in large deformations and time-integration methods for non-linear beams and rotations.
Professor Jose Munoz.
Jose is working with Andrei Lyamin, Kristian Krabbenhoft and Jinsong Huang on sequential limit analysis in the Georisk program and will be at the CGSE from July to September 2013.
QUANTITATIVE RISK ASSESSMENT OF LANDSLIDES
Numerous studies have been undertaken in recent years to develop rigorous methods for estimating the probability of failure, pf. Upon determining pf, it is possible to calculate the risk, R, through the simple relation R = pfC, where C is the consequence of failure.
The above method for evaluating risk works well for systems that have a single failure mode. In landslide problems, however, multiple failure modes can coexist. Because failure and consequence are correlated, the consequence associated with each failure mode should be assessed individually. The risk must be redefined as
where pi and Ci are the probability and consequence of failure number i and nf is the number of failures. The new definition of risk requires the assessment of pi and Ci individually for each failure. This can be easily achieved in the framework of Monte Carlo simulation. The new and traditional methods are contrasted in the two flow charts below, where Nsim is the number of simulations.
A shallow failure
A deep failure
It is clear that the consequences associated with the two failures are very different, which implies the necessity to assess consequence individually for each failure.
The figure on the left is the histogram of sliding mass from 2000 lower bound simulations of a two layer undrained slope. It shows clearly two dominant failure mechanisms. It also shows that the size of the sliding mass varies over a wide range.
Conclusions: A new framework of quantitative risk assessment for landslides is proposed, which is based on the logic that the consequence should be assessed individually for each failure mode. Although only landslide risk is considered, the framework is generally applicable to other types of risk assessment in civil engineering.
Key Researchers: Dr Jinsong Huang, Professor Andrei Lyamin, Professor D. Vaughan Griffiths, Associate Professor Kristian Krabbenhoft and Laureate Professor Scott Sloan.