Geotechnical Modelling (applied Geotechnics)

Geotechnical modelling David Muir Wood Version 2.2 April 2004 Preface Modelling forms an implicit part of all engineering design but many engineers are not aware either of the fact that they are making assumptions as part of the modelling or of the nature and consequences of those assumptions. Many engineers make use of numerical modelling but may not have stopped to think about the approximations and assumptions that are implicit in that modelling— still less about the nature of the constitutive models that may have been invoked. Many engineers are probably not aware of the possibilities and implications of physical modelling either at single gravity or on a centrifuge at multiple gravities. I have worked for many years at the interface between research and industry in developing numerical models of soil behaviour and in attempting to explain to practising engineers the possibilities of soil modelling. In particular, in 1996 and 1997 I held a Royal Society Industry Fellowship to be seconded to work within Babtie Group with both geotechnical and structural engineers and as a result became more aware of the realities of the conditions within typical consulting engineering companies. This book was conceived during that secondment. The scope of the book attempts to cover the range of guidance that I believe that engineers who are undertaking geotechnical modelling need. I hope that they will find the approach accessible. Much of the material in this book has been developed during courses given to final year MEng and postgraduate students at Bristol University and elsewhere. The reader is assumed to have a familiarity with basic soil mechanics and with traditional methods of geotechnical design. Some modest mathematical ability is expected: this is not intended to deter, but rather to indicate the nature of the theoretical understanding that is necessary if geotechnical modelling is to be safely undertaken. My previous book Soil behaviour and critical state soil mechanics (Muir Wood, 1990) used a particular constitutive model for soil behaviour, Cam clay, as a vehicle for describing the mechanical behaviour of soils and of some simple geotechnical structures. While Cam clay is presented briefly in section §3.4.2, this present book deliberately tries not to repeat too much of the material in that earlier book: there is more description of simple alternative constitutive models and of the modelling of a range of geotechnical systems. The two books should be seen as complementary. I am grateful to the Royal Society for the Industry Fellowship and to Babtie Group for welcoming me into their midst: they may not have anticipated that this would have been the outcome. This book project has inevitably lingered iii iv Preface and I am grateful to Bristol University for giving me a University Research Fellowship during academic year 2002-2003 in order to give me slightly more time to work on the manuscript. The final surge to completion was greatly helped by a Visiting P