Page 179 - Rock Mechanics For Underground Mining

PROBLEMS

Figure 5.12 A section of the stress principal stresses which can be incorporated in site investigations and preliminary
map of the world, showing orienta- design and scoping studies. A map of this type is also valuable in other fields of
tions of horizontal principal stresses
resource engineering. For example, considering the Australian continental land mass,
in and around the Australasian plate
Mukhamadiev et al. (2001) showed that, by analysis of the horizontal principal stress
(after Reinecker et al., 2003).
orientations, after constructing the principal stress trajectories it was possible to de-
duce the macroscopic state of stress throughout the continental block. An important
result from the analysis was that it suggested the existence of a singular point in the
interior of the Australian continent, where the ratio k of the horizontal stresses is
unity. This has significant implications for exploitation of petroleum and geothermal
energy resources in the region, which might depend on hydraulic fracture treatments
for their economic recovery.

Problems

1 At a particular site, the surface topography can be represented in a vertical cross
section by a vertical cliff separating horizontal, planar ground surfaces, as shown
in the figure (a) below. The upper and lower surfaces AB and CD can be taken to
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