7 Introduction
1.1 The subject of rock mechanics
The subject of rock mechanics started in the 1950s from a rock physics base
and gradually became a discipline in its own right during the 1960s. As
explained in the Preface, rock mechanics is the subject concerned with the
response of rock to an applied disturbance, which is considered here as an
engineering, i.e. a man-induced, disturbance. For a natural disturbance,
rock mechanics would apply to the deformation of rocks in a structural
geology context, i.e. how the folds, faults, and fractures developed as
stresses were applied to the rocks during orogenic and other geological pro-
cesses. However, in this book we will be concerned with rock mechanics
applied to engineering for civil, mining, and petroleum purposes.
Thus, rock mechanics may be applied to many engineering applications
ranging from dam abutments, to nuclear power station foundations, to the
manifold methods of mining ore and aggregate materials, to the stability
of petroleum wellbores and including newer applications such as
geothermal energy and radioactive waste disposal. Probably, the main
factor that distinguishes rock mechanics from other engineering disciplines
is the application of mechanics on a large scale to a pre-stressed, naturally
occurring material.
In the two photographs in Figs 1.1 and 1.2, we illustrate a typical full-
scale rock structure and a closer view of the rock material itself. It is quite
clear from these illustrations that the nature of the rock mass and the rock
material must be taken into account in both the basic mechanics and the
applied engineering. This has been increasingly appreciated since the
beginning of the discipline in the early 1960s.
In the civil and mining engineering areas, the subject of rock mechanics
flourished in the 1960s. In 1963, a particular landmark was the formation
of the International Society for Rock Mechanics which has grown steadily
to its current membership of about^7000 from^37 countries. The discipline
of rock mechanics is universal in its application and the engineering is
especially visible in those countries where the ground surface is predomi-
nantly composed of rock, for example, Chile, Finland, Scotland, Spain, and