Engineering Rock Mechanics

Questions and answers: rock mechanics interactions and rock engineering systems 239

414.8 Assume that the interactions in the matrix required by 414.4
(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, de-
velop its 'Cause-Effect' (C,€) co-
ordinates. These are the sums of
the values in the row and column
through each principal factor.
For example, the (C,€) co-ordin-
ates for principal factor F are
C=l+4+1=6and
E = 1 + 1 + 2 = 4, i.e. (6,4). Hence establish the interaction intensity,
C+€, and dominance, C-E, of each principal factor in the interactive
system. Then plot the four principal factors using Cause and Effect
axes.

A 14.8 The required values are given in the following table.

Principal Factor C E C+E C-E

interactive intensity dominance

Fractures, F 64 10

RockStress,S 4 5 9

Water Flow, W 6 9 15

Construction,C 7 5 12

2

-1

-3

2

The principal factors, F, S, W and

C are plotted in Cause-Effect space in

the diagram to the right.

to illustrate the Cause-Effect co-ordin-

ates for principal factors in the inter-

action matrix, the maximum possible

values of the co-ordinates are (12J2).

Thus, the co-ordinate values of F(6,4),

S(4,5), W(6,9) and C(7,5) indicate that

the interaction matrix system struc-

ity. The principal factor W, Water Flow,

has the greatest interactive intensity, represented by a C + E value of 15.

In the plot above, more interactive factors plot further along the C = E

For this example, which is included Effect, E

ture has a medium interactive intens- Cause, C