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Through a series of projects funded by the Australian Coal Industry Research Association (ACARP), we have developed a rock mass rating scheme for coal measure rocks which draws upon the compositional data contained within the geophysical logs as well as the sonic data. The scheme is known as the Geophysical Strata Rating (GSR) and our approach has some similarity to the method proposed by Barton for estimating Q-value from seismic velocity corrected for porosity and depth. As with other rating schemes, it also considers the properties of the intact rock mass as well as defects. These aspects of the GSR will be explained.

GSR data are obtained for the full length of each borehole. Data in this form can be used as input for the construction of 3D geotechnical models. For coal mining, we can extract information on key horizons and units so as to assist with decisions relating to bolting, caving and roadway stability. In this talk I will also provide examples of the use of the GSR in the construction of 3D geotechnical models.

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Every year piling rigs fall over or are subject to near misses due to inadequately prepared or maintained site surfaces – often such incidents involve potential fatalities or serious injury to operatives and extensive damage to equipment. Modern piling equipment is becoming increasingly heavy, often with higher centres of gravity, to cater for the demand for deeper and larger diameter foundations to take higher load capacities.

In Europe and in particular the UK, there has been a coordinated effort by piling federations and the geotechnical fraternity to improve practices related to the use of piling and associated plant, with the aim of improving safety on construction sites. The Federation of Piling Specialists (FPS) in the UK contracted the Building Research Establishment Ltd (BRE) to produce a guide to the design of working platforms.

The guide entitled, “Working Platforms for Tracked Plant”, was released in 2004 and notes in the foreword that the guide is not intended to reduce the designer’s input, but rather to promote the implementation of minimum design, installation, repair and maintenance standards. In Australia, the Piling & Foundation Specialists Federation (PFSF) is currently promoting awareness of the BRE guide and the importance of forming and maintaining good working platforms to the construction industry.

A working platform is the foundation for a piling rig and as such, geotechnical engineers are well qualified to design and specify the platform. The presentation describes the process of designing working platforms and what information is needed in terms of rigs pressures, types of loading and soil parameters. A common problem for the platform designer occurs in situations where pile foundations are to be used, where there is usually a lack of information within the geotechnical report on the upper soil profile, the critical zone of interest for the platform.

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Dryland Salinity is an issue that has become increasingly apparent with urban expansion across Australia, affecting buildings, infrastructure and the environment. This presentation covers an overview of the occurrence, salinity processes, engineering issues, investigation methodologies, assessment of impacts, design related management planning / reporting, monitoring and adoption of salinity techniques within DA certification requirements.

The presenter has conducted and reviewed dryland salinity related to investigations; management planning; reporting; training; presentations and incorporation of salinity measures as part DA requirements over the last 11 years.

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The Young Geotechnical Professionals’ Night is an opportunity to see four selected presentations by young geotechnical professionals discussing interesting and challenging aspects of their work. After the presentations, you will have a chance to catch up with friends and the presenters over drinks and finger food, and see additional posters prepared by YGP’s. The following presentations will be given during the evening.

Finite Difference Modelling of Soil-structure Interaction for Seismic Design at Moment Resisting Building Frames

Hamid Reza Tabatabaiefar

The importance of Soil-Structure Interaction (SSI) both for static and dynamic loads has been well established and the related literature spans at least 30 years of computational and analytical approaches for solving soil–structure interaction problems. In the present study, a ten storey moment resisting building frame, resting on shallow foundation, is selected in conjunction with three different soil types with different properties. The structure is modelled considering the three types of the soil deposits employing Finite Difference approach using FLAC 2D software. Fully nonlinear dynamic analysis under influence of different earthquake records is conducted, and the results of the different cases are compared and discussed.

Three Dimensional Geometric Modelling for the Construction of the Northwest Corner of the Port Botany Expansion Project

Keiran Wright

The Port Botany Expansion (PBE) project involves the construction of an extension to the existing port in Botany Bay, Sydney. A new Tug Berth is located in the North-West corner of this port expansion, and provides berthing for tug vessels associated with the operation of the port. The design and construction of this berth, and the North-West corner of the PBE project was heavily constrained by the geometric requirements of the project. This geometric complexity posed significant challenges in the staging of construction. As a consequence, three dimensional (3D) construction staging models were developed by the design team to assist in knowledge transfer through the construction process. This paper discusses the development of these staging models, and the benefits that were seen on the project as a result. It also presents some lessons learnt through the design and construction process which could be beneficial for similar future projects.

Analysis, Design, and Construction Stages of Milad Geosynthetic Reinforced Soil Bridge Abutment in Tehran, Iran

S.Alireza Mirlatifi (Sam)

Reinforced soil walls are one the most cost effective options for retaining structures, and are being increasingly used in recent years around the world. They have also proved that they have performed to an acceptable level under earthquake loading conditions. This paper presents the analysis, design, and construction stages of the first major geosynthetic reinforced soil bridge abutment built in Iran. This abutment is analysed using both Limit Equilibrium Methods (LEM) for stability analysis and Finite Element Method (FEM) for deformation analysis under static and seismic loads. This project was undertaken on behalf of the Tehran Municipality with the aim of bringing this new method of abutment construction to the country. This project is likely to be the first of many to adopt this cost effective solution and presents lessons learned in the design and construction phases.

Tube-A-Manchette Geo-Nails as Applied at Toombul on the Brisbane Airport Link

Tecwyn Griffiths

Brisbane Airport Link (BAL) is a $4.8 billion infrastructure project, the largest road infrastructure project in Australia. The Airport Link will be the first major motorway linking Brisbane city to the Northern suburbs and airport precinct, with the majority of the 6.7km toll road being underground. A section of the Airport Link at Toombul involved constructing a tunnel underneath a live railway line embankment. To do this a box culvert road tunnel is to be jacked underneath the live railway embankment. This presented many geotechnical challenges to the client, and a solution involving the construction of contiguous bored piled walls, diaphragm walls, jet grouting, canopy tubes, and soil nails was implemented. The solution Keller Ground Engineering (KGE) offered consisted of installing Tube-a-Manchette Geo-Nails (TGNs). TGNs provide slope reinforcement in the same manner as a regular soil nail; however, where a TGN differs from a regular soil nail is the addition of a second phase grouting which improves surrounding soil strengths. The project provided many technical challenges for KGE such as drilling to 55m with a target deviation of less than 500mm. This and other aspects presented many difficulties with lessons learnt along each stage of the construction process. These challenges and obstacles were overcome, with KGE providing an innovative solution to stabilising the site in advance of the major tunnel jacking process.

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The northern batter of the Yallourn mine collapsed suddenly on the 14th November 2007. The collapse had dramatic consequences with loss of 20% of Victoria’s power generation capacity and a cost to the mine measured in hundreds of millions of dollars. Because this was a surprise to government and because of the consequences, the government of Victoria decided to hold an Inquiry into the causes and appointed a Mining Warden for the period of the Inquiry. Like all great failures there are lessons to be learnt and this presentation presents the results of the Inquiry and the lessons learnt.

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Historically, geotechnical stability analysis has been performed by a variety of approximate methods that are based on the notion of limit equilibrium. Although they appeal to engineering intuition, these techniques have a number of major disadvantages, not the least of which is the need to presuppose an appropriate failure mechanism in advance. This feature can lead to inaccurate predictions of the true failure load, especially for cases involving layered materials, complex loading, or three-dimensional deformation.

This lecture will describe recent advances in stability analysis which avoid these shortcomings. Attention will be focused on new methods which combine the limit theorems of classical plasticity with finite elements to give rigorous upper and lower bounds on the failure load. These methods, known as finite element limit analysis, do not require assumptions to be made about the mode of failure, and use only simple strength parameters that are familiar to geotechnical engineers. The bounding properties of the solutions are invaluable in practice, and enable accurate solutions to be obtained through the use of an exact error estimate and automatic adaptive meshing procedures. The methods are extremely general and can deal with layered soil profiles, anisotropic strength characteristics, fissured soils, discontinuities, complicated boundary conditions, and complex loading in both two and three dimensions. Following a brief outline of the new techniques, stability solutions for a number of practical problems will be given including foundations, anchors, slopes, excavations, and tunnels.

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Geotechnical engineers play a critical role in managing the performance of large geographically distributed systems that are affected by geohazards such as earthquakes, floods, hurricanes, and landslides. Systems, such as water supplies, levees, and gas and liquid fuel supply networks, may cover thousands of km2 and be subject to many different ground response and geotechnical failure mechanisms. The geotechnical factors affecting system behaviour have broad implications for life safety and regional economic stability.

The lecture will explore the geotechnical aspects of large system behaviour during extreme natural events, starting with the performance of system components under extreme conditions of soil- structure interaction. The results of large-scale laboratory tests of underground pipeline response to ground rupture will be summarized. The results will be used to illustrate how such testing not only improves our understanding of complex soil-structure interaction, but leads to improvements in geotechnical instrumentation and modelling of soil behaviour. The geotechnical factors affecting regional system response to geohazards will be examined with reference to earthquake effects on the Los Angeles and San Francisco water distribution networks as well as hurricane effects on both the New Orleans levee system and Gulf of Mexico oil and gas pipeline supply network. The lecture will explore the implications of recent earthquakes in Christchurch, New Zealand and the Tohoku, Japan earthquake with respect to low probability/high consequence events and the worldwide need to protect critical infrastructure.

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The need to design safe foundations for offshore and near shore structures has generated greater interest in coastal and marine geotechnics, today an important element in geotechnical engineering. Achieving safe foundation design requires continuing evolution and discussion of design practices and construction techniques by geotechnical and marine professionals.

The Symposium will present state-of-the-art practices, innovative technologies, new research results and case histories in the field of coastal and marine geotechnics. The Symposium will bring together the broad community of marine and geo-professionals working in offshore and near shore geotechnical design. The goal of this symposium is to provide professional engineers, researchers, specialist contractors, regulators, educators, and engineering students the opportunity to meet and share their knowledge and experiences in coastal and marine geotechnics.

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In this talk the general requirements for O-cell instrumentation will be presented, including the differences in instrumentation required for O-cell bi-directional static load tests to conventional load tests, purpose and numbers of various embedded instruments, parameters that need to be measured, instrumentation for additional geotechnical parameters, calculation of plate movements – single level and multi level tests, assessment of the additional elastic compression adjustment required for an O-cell test in comparison to a top-loaded test and the advantages and limitations of single/multi-level O-cell tests.

The added value gained from including strain gauge and extensometer instrumentation will also be discussed. Practical details on the locations and number of strain gauges, assessment of load distribution along the shaft and the use of retrievable gauges in CHSL pipes will be presented together with the importance of actual pile section area, the use of tangent stiffness in the assessment of pile stiffness values and an introduction to the Sonicaliper®.

Methods for the construction of the top-loaded load-displacement behaviour will be presented using the computation methods of summing the measured behaviour or summing the modelled behaviour.

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This talk will present an overview of many of the significant projects on which Andrew has worked. It will include discussion of the salient features and present the “take-away” lessons from a number of geotechnical projects; it will include discussion of the background to the development of the Landslide Risk Management framework for Australia, and in particular the challenges and issues in bringing the framework to fruition; and it will include discussion of the particularly challenging features of a current project relating to management of infrastructure beneath the Main Southern Railway south of Sydney, whilst permitting safe operation of the railway and unimpeded underground longwall mining.