Lessons Learnt from Numerical Analyses of Geotechnical Problems

Mostafa Ismail & Sergei Terzaghi

This presentation will be in two parts with Dr Mostafa Ismail leading the main presentation with a closing presentation by Sergei Terzaghi on specific numerical modelling for tunnels including a brief commentary on soil-structure interaction effects.

Complexity of soil structure interaction problems is increasing due to continuing demand on existing infrastructures, including tunnelling, underpinning activities, vibration control, as well as extension of existing facilities. This complexity is normally exacerbated by potentially very complex geotechnical conditions and possible requirements for ground improvements to otherwise inferior ground conditions. Handling such complexities requires high level of numerical expertise, clear understanding of soil behaviour, awareness of limitations of existing numerical tools and willingness to mitigate inherent risk by undertaking efficient site investigation and lab testing campaigns. This presentation covers a few lessons learnt from projects involving numerical analysis from Australia and overseas with focus on tunnelling. The lessons highlight some of the critical issues to consider when modelling soil-structure interaction problems. Focus is made on modelling and calibration of parameters of soft clay, selection of constitutive models, determination of model parameters and associated sensitivity analyses, and details required to model structural elements. Emphasis and reference will be made to laboratory testing and how this can be used to determine and calibrate soil parameters.

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