Additional points 369here, the water is flowing horizontally across the page as this is the
direction of the major principal stress. We can see that the boundary
stress is greatest in those regions where the flowing water would first
come into contact with the obstruction, and that the regions of tensile
stress coincide with where we would expect eddies, or turbulence, to
occur behind the obstruction.
minimum stress =S=19.3 Additional points
We have emphasized the basic principles and techniques involved in
considering underground excavation instability mechanisms. There is
no substitute for this basic understanding of the 3-D geometry of rock
Figure 19.6 Visualizing a rock mass dissected by four fracture sets.