456 Questions 74.7-14.70: rock mechanics interactions
Q14.6 Each off-diagonal term in the interaction matrix represents a
mechanism linking two principal factors. If a mechanism involves three
or more principal factors, their combined interaction is represented by
pathways through the interaction matrix. With reference to the interac-
tion matrix required by 414.4, show the example pathway representing
how Construction blasting affects the Rock Stress around an excavation,
which allows Fractures to open, leading to increased Water Flow which
then affects Construction.
Q 14.7 Assume that you have been asked to undertake a technical audit
of a rock engineering design for a DIANE rock mass, where a CHILE
numerical code has been used to determine the elastic rock stresses
and displacements around an underground excavation. List briefly the
likely sources of error in the determination of the rock stresses and
displacements.
414.8 Assume that the interactions in the matrix required by Q14.4
(which has the principal factors of Fractures, Rock Stress, Water Flow,
and Construction) have been considered for a specific rock mass and
engineering objective. Each interaction has been assigned a number
according to the following scheme:
0 - no interaction;
1 - weak interaction;
2 - medium interaction;
3 - strong interaction;
4 - critical interaction.
These numbers are shown in the
matrix to the right.
For each principal factor, develop
its 'Cause-Effect' (C, E) co-ordin-
ates. These are the sums of the val-
ues in the row and column through
each principal factor.
For example, the (C, E) co-ordin-
ates for principal factor F are C =
1 + 4 + 1 = 6 and E = 1 + 1 + 2 = 4, i.e. (6,4). Hence establish the
interaction intensity, C + E, and dominance, C - E, of each principal
factor in the interactive system. Then plot the four principal factors using
Cause and Effect axes.
Q 14.9 In developing a rock mass classification system for estimating the
relative instability of natural rock slopes in the Italian Alps (Mazzoccola
and Hudson, 1996), the following parameters were chosen.