'Engineering geology' is one of those terms that invite definition. The American Geological Institute, for example, has expanded the term to mean 'the application of the geological sciences to engineering practice for the purpose of assuring that the geological factors affecting the location, design, construction, operation and mainten ance of engineering works are recognized and adequately provided for'. It has also been defined by W. R. Judd in the McGraw-Hill Encyclopaedia of Science and Technology as 'the application of education and experience in geology and other geosciences to solve geological problems posed by civil engineering structures'. Judd goes on to specify those branches of the geological or geo-sciences as surface (or surficial) geology, structural/fabric geology, geohydro logy, geophysics, soil and rock mechanics. Soil mechanics is firmly included as a geological science in spite of the perhaps rather unfortunate trends over the years (now happily being reversed) towards purely mechanistic analyses which may well provide acceptable solutions for only the simplest geology. Many subjects evolve through their subject areas from an interdisciplinary background and it is just such instances that pose the greatest difficulties of definition. Since the form of educational development experienced by the practitioners of the subject ulti mately bears quite strongly upon the corporate concept of the term 'engineering geology', it is useful briefly to consider that educational background."

The first edition of this book was received more kindly than it deserved by some, and with some scepticism by others. It set out to present a simple, concise and reasonably comprehensive introduction to some of the theoretical and empirical criteria which may be used to define rock as a structural material. The objectives - reinforced by the change in title - remain the same, but the approach has been changed considerably and only one or two sections have been retained from the first edition. The particular aim in this edition is to provide a description of the mechanical behaviour of rocks, based firmly upon experimental data, which can be used to explain how rocks deform, fracture and yield, and to show how this knowledge can be used in design. The major emphasis is on the behaviour of rocks as materials, although in the later chapters the behaviour of discontinuities in rocks, and the way in of rock masses, is considered. which this can affect the behaviour If this edition is an improvement on the first edition it reflects the debt lowe to numerous people who have attempted to explain the rudiments of the subject to me. I should like to thank Peter Attewell and Roy Scott in particular. I should also like to thank Tony Price and Mike Gilbert whose work at Newcastle I have used shamelessly.

Coal Mine Structures is based on a six-year study, carried out at the University of Newcastle upon Tyne between 1976 and 1982 and financed by the National Coal Board and the European Coal and Steel Community (Projects 7220 - ACj806 and 7220 - ACj814), into the behaviour of under ground openings in British coal mines. The original work has been expanded to include other relevant British and international data. How ever, it remains, deliberately, a personal view based on a specific - albeit broad - research programme. It does not pretend to be a complete description of the behaviour of shafts, tunnels, rooms, pillars and long wall excavations. Nor does it set out to provide a manual for design. The specific aim is to show, often through consideration of quite detailed laboratory and field data, how the observed performance of some under ground structures during mining, can be explained by the deformation characteristics of the rocks which surround them. The work is based on observatiollB by many engineers working for the National Coal Board's Mining Research and Development Establishment, and by research associates and postgraduate students at the University of Newcastle upon Tyne. I am grateful to them all, but I am particularly indebted to Dr A. H. Wilson and Mr M. J. Bell of the National Coal Board, to Dr P. F. R. Altounyan, Dr P. Garritty, Dr P. Holmes, and Dr P. D. Shelton formerly of the University of Newcastle upon Tyne, to Dr R. N."

Rock masses comprise systems of discontinuities developed by tectonic action or diagenesis, and occasionally imposed by excavation, which bound blocks of intact rock. Fluid flow is determined by distribution of the discontinuities and by the way in which their apertures respond to natural and imposed stress fields in the rock masses.