Engineering Rock Mechanics

224 Rock mechanics interactions and rock engineering systems (RES)

Discontinuous rock mass

/ Local stress field affected by

-/ discontinuities

High normal stresses reduce

discontinuity permeability

could alter the mechanical and hydrogeological properties

Interaction 6: (Stress/rock structure)

'I

the rock structure

4

/ High stresses can alter '

t t t

Figure 14.1 Six of the main rock mechanics interactions.

water flow. The interactions annotated (1)-(6) in the figure are listed below.

Interaction 1: Rock structurelstress-stress field affected by discontinuities.

Interaction 2: Rock structurelwuterflow-water preferentially flows along

Interaction 3: Stresslwuter flow-high normal stresses reduce discon-

Interaction 4: Wu terflowlstress-water pressure in discontinuities reduces

Interaction 5: Wuterflowlrock structure-water flow causes discontinuity

Interaction 6: Stresshock structure-high stress can alter the rock structure.

The figure shows the interactions occurring around an underground

excavation but a similar diagram could be drawn for any rock engineering

application. Also, these are only six of a large number of interactions which

occur in rock mechanics and during rock engineering: we have chosen

these because of their fundamental nature.

Interaction matrices are used to provide a systematic approach to the

interactions. Generally, matrices are used as assemblages of detached

coefficients, subject to agreed manipulative procedures for mathematical

utility. However, the basic presentational approach is also useful if the

matrix components are concepts, or subjects, and the interactions between

discontinuities.

tinuity permeability.

effective normal stress.

surface alteration.