Instabilities Modeling In Geomechanics

Instabilities Modeling in Geomechanics describes complex mechanisms which are frequently met in earthquake nucleation, geothermal energy production, nuclear waste disposal and CO2 sequestration. These mechanisms involve systems of non-linear differential equations that express the evolution of the geosystem (e.g. strain localization, temperature runaway, pore pressure build-up, etc.) at different length and time scales. In order to study the evolution of a system and possible instabilities, it is essential to know the mathematical properties of the governing equations. Therefore, questions of the existence, uniqueness and stability of solutions naturally arise. This book particularly explores bifurcation theory and stability analysis, which are robust and rigorous mathematical tools that allow us to study the behavior of complex geosystems, without even explicitly solving the governing equations. The contents are organized into 10 chapters which illustrate the application of these methods in various fields of geomechanics.

In this volume a number of developments on a variety of topics have been reported. These topics include: partially saturated soil; instabilities in soil behaviour; environmental geomechanics; parallel computing; and applications to tunnels, embankments, slopes, foundations and anchors.

Sixty-five papers cover a wide range of topics from engineering applications to theoretical developments in the areas of embankment and slope stability, underground cavity design and mining; dynamic analysis, soil and structure interaction, and coupled processes and fluid flow.

This book contains a sampling of papers presented at the June 2-5, 2002 International Workshop on Bifurcations andamp; Instabilities in Geomechanics (IWBI 2002). The scope of the Workshop includes analytical approaches, numerical methods, and experimental techniques.

Sixty-five papers cover a wide range of topics from engineering applications to theoretical developments in the areas of embankment and slope stability, underground cavity design and mining; dynamic analysis, soil and structure interaction, and coupled processes and fluid flow.

This is an up-to-date review of developments in the field of bifurcations and instabilities in geomechanics from some of the world’s leading experts. Leading international researchers and practitioners of the topics debate the developments and applications which have occurred over the last few decades. Beside fundamental research findings, applications in geotechnical, petroleum, mining, and bulk materials engineering are emphasised.

Linear mathematical assumptions for procedures in other branches of engineering have little relevance for geoengineering, which must accommodate non-linear behaviors. Contributors to eight papers apply the breakthrough numerical modeling Distinct Element Method (Cundall, late 1960s). The design philosophy for structures or excavations in geotechnical engineering is different from that followed for fabricated materials like steel and concrete. The designer has little data both with regard to geological weaknesses and strength and deformation characteristics of materials before finalizing the designs. Also these characteristics vary from place to place. In-situ stresses due to gravity and tectonics and transient forces imposed due to rainfall and earthquakes make the matter more complicated. The pore waters carry the load initially before passing it on to the solids. For the analytical procedure, to be realistic, it should account for large displacements and non-linear behaviour including strain-softening. Because of these considerations, the designers have followed procedures based on simplifying assumptions such as linear, small strain, elastoplastic behaviour. Numerical procedures based on such assumptions, though very popular in other branches of engineering, have made little impact in geo-engineering. An attempt has been made in this book to compile the recent use of distinct element codes for solutions of some of the problems in geomechanics — particularly those involving excavations. It is hoped that it will provide an opportunity for the fraternity of geotechnical engineers to appreciate the opening of new frontiers in the use of computers for solving more challenging geotechnical problems.

Reflecting the current research and advances made in the application of numerical methods in geotechnical engineering, this volume details proceedings of the Ninth International Symposium on 'Numerical Models in Geomechanics - NUMOG IX' held in Ottawa, Canada, 25-27 August 2004. Highlighting a number of new developments in the area, papers concentrate upon the following four main areas: * constitutive relations for geomaterials * numerical algorithms: formulation and performance * modelling of transient, coupled and dynamic problems * application of numerical techniques to practical problems. Representing the most advanced, modern findings in the field, Numerical Models in Geomechanics is a comprehensive and impeccably-researched text, ideal for students and researchers as well as practising engineers.