Sydney Chapter

Young Geotechnical Professional’s Night


Ana Heitor: Characterisation of Compacted Soil Using Shear Wave Velocity
Field compaction testing is widely undertaken using nuclear density meters. Due to its localized nature however, the method is limited in assessment over larger depths and wider surface areas. Only a few studies have evaluated compacted soil behaviour under unsaturated conditions using alternative non-destructive testing, namely shear wave velocity surveys. In this presentation, the results of laboratory testing on sets of compacted silty sand samples are discussed. Under different confining pressures, the shear wave velocity and matric suction of each specimen were measured using bender elements and a small tip tensiometer. Novel relationships between the measured values are proposed along the compaction curve.

Ben Rotter: Robust Geotechnical Solutions in the Face of Limited Data
Engineers frequently deal with projects that significantly lack subsurface data. This results in substantial uncertainty in conceptual models and the geological and parameter inputs for numerical models and analytical solutions. This presentation discusses the challenges associated with conducting analyses, and developing and utilising conceptual and numerical models of the subsurface, with uncertain and/or limited data. Techniques to assess uncertainty and better constrain models are presented, with particular attention given to conceptual model development, numerical model calibration and stochastic uncertainty analysis methods.

Shiao Huey Chow: Soil Strength Estimation using Free Falling Penetrometers
A free falling penetrometer can be a cost effective solution for obtaining soil strength parameters at sites with poor accessibility. This has led to the development of numerous penetrometer systems. For example, these penetrometers (retrievable or expendable) can be deployed from small vessels and be allowed to free-fall into the seabed. However, free falling penetrometer application is not widespread due in part to difficulties in data interpretation. There is a lack of appropriate theory and well controlled experimental data to estimate the rapid penetration resistance of the soil. This presentation investigates the interpretation of undrained shear strength parameters from free falling penetrometer results through a series of laboratory model tests.

Daniel Barnes: Behaviour of Tunnel Rock Subject to Fire Loading
A number of recent incidents involving fires in tunnels have indicated the need to investigate the properties and characteristics of tunnel materials under fire situations. Most studies so far have focused on concrete and related materials rather than natural materials such as supporting rock. This presentation looks at a preliminary analysis of the behaviour of sandstone in Sydney tunnels when exposed to fire using PLAXIS, a Finite Element Modelling (FEM) program, and follows from previous research including large and small scale fire testing.

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