8 Introduction
\
7Analysis of individual subjects
7
Foundation(^444) ..1 I
/-Analysis of coupled mechanisms 7
Rock mechanics interaction matrices -
e.g. block analysis or stress analysis 3
7
/=Complete rock engineering problems
LKnowledge-based expert systems /
,,,, edi'
II
shaft
A $3 Borehole/
Underground
excavation
- xs\%G' r' /E$'''-
9 - Boundary
conditions: - In siru stress,
hydrogeological regime
Figure 1.12 Three-tier approach to all rock engineering problems.
between rock stresses and rock structure in the rock mechanics context;
and there will be relations between rock support systems and cost
implications in the rock engineering context.
finally, the central ring represents the individual aspects of each project,
such as a specific numerical analysis or a specific costing procedure.
In the spirit of this diagram, we discuss the major rock mechanics aspects
on an individual basis in Chapters 2-13. The method of studying the
interactions between subjects is discussed in Chapter 14. Then, in
Chapters 15-20, the main engineering techniques and applications are
discussed. In engineering practice, the procedure is to enter the diagram
in Fig. 1.12 from the outside having specified the objective, pass through
the three rings conducting the necessary analyses at each stage, and then
exit synthesizing the most appropriate design.
We have already mentioned that in rock mechanics there was
considerable emphasis in the 1960s on intact rock and in the 1970s on
discontinuities and rock masses. In the 1980s the emphasis shifted to
numerical analysis and we anticipate that, during the remaining part of the
1990s and beyond, there will be combined emphases on material property
determination, full-scale in situ experiments, enhanced use of the
computer, and improved engineering implementation of the principles.
Currently, our ability to compute has far outstripped our ability to measure
the required input parameters and indeed to know whether the computer
modelling is realistic. A good example of this is the theory of elasticity
which considers stresses and strains in the rock. The vast majority of
elasticity analyses have assumed that the rock is isotropic, i.e. it has the
same elastic properties in all directions, which requires two elastic
properties. We now recognize that it is more realistic to include further
elastic properties, five elastic constants for transverse isotropy (the