Questions 14.1 -1 4.1 0:
rock mechanics
interactions and rock
engineering systems
4 14. 1 Explain with a one-sentence answer how, in a rock mass,
(a) the rock stress can affect water flow in fractures,
(b) the water pressure in fractures can affect the rock stress,
(c) the fractures can affect water flow,
(d) water flow can affect the fractures,
(e) the fractures can affect rock stress, and
(f) the rock stress can affect the fractures.414.2 Draw an interaction matrix having Fractures, Rock Stress, and
Water Flow as the leading diagonal terms. Insert the letters representing
the six mechanisms in Q14.1 in the appropriate off-diagonal boxes of the
interaction matrix.414.3 Under what conditions is a matrix symmetrical? Why will almost
all rock mechanics interaction matrices be asymmetrical?414.4 In order to consider also the interaction of rock engineering
activities with the rock mechanics factors, extend the 3 x 3 interaction
matrix of Q14.2 to a 4 x 4 interaction matrix by adding the extra leading
diagonal term CONSTRUCTION. Write a one-phrase explanation of the
content of each of the six extra off-diagonal interaction boxes introduced
by adding the leading diagonal term, CONSTRUCTION.
414.5 The use of the interaction matrix is helpful for thinking about
any problem involving manifold factors. The principal factors, located
on the leading diagonal, are established first. Then, the interactions,
i.e. the mechanisms linking the principal factors, are considered in the
off-diagonal positions.
For example, when studying natural fractures in the rock mass, as-
sume that we are interested in the four parameters of fracture orient-
ation, spacing, extent (or persistence) and roughness. Using these four
parameters as the leading diagonal terms of a 4 x 4 interaction matrix,
identify the content of the 12 off-diagonal boxes and hence show that the
parameters are likely to be related.