Rock mechanics
74 interactions and
rock engineering
systems (RES)
In this chapter, we introduce a method of structuring all the ways in which
rock mechanics parameters and variables can affect one another-the rock
mechanics interactions. The method is presented within the wider context
of an approach to integrate all the relevant information in rock engineering
design and construction, rock engineering systems, Hudson (1992). The
interaction matrix is explained first with examples and a general consid-
eration of the nature of matrix symmetry. Then larger matrices are
discussed demonstrating the links between rock mechanics and rock
engineering, especially the pre-construction and post-construction inter-
actions. Further example applications are given so that readers will feel
confident in generating their own matrices for any problem. The RES
approach aims to identify the parameters relevant to a problem, and their
interactions, thus providing overall coherency in approaching rock
mechanics and rock engineering problems.
Referring back to Fig. 1.12, the three-tier approach to all rock engineering
problems, the inner ring represents the analysis of individual subjects. The
chapters in this book have so far followed such single-subject themes but
this chapter is about interactions and coupled mechanisms (represented by
the middle ring of Fig. 1.12). It is only through the understanding of these
interactions that we can arrive at the outer ring of Fig. 1.12 and the
corresponding solution of complete rock engineering problems using
theory and experience.
The need to study the interactions has always been present. Now we have
much better computational capability and are being faced with increasingly
large and complex problems in which it is by no means clear what the main
factors are, how they interact, and how best to build the most appropriate
conceptual, mathematical, numerical or mechanical models.
14.1 Introduction to the subject
In several of the earlier chapters, we have touched on the fact that one rock
mechanics parameter can affect another. This is illustrated in Fig. 14.1,
which shows the six binary interactions of in situ stress, rock structure and