Page 265 - Rock Mechanics For Underground Mining

IDENTIFICATION OF POTENTIAL BLOCK FAILURE MODES – BLOCK THEORY

Figure 9.5 Stereographic projection
of a plane, illustrating different do-
mains for the upper and lower half-
spaces of the plane (after Goodman,
1989).

Figure9.6 Constructionofgreatcir-
cles and identification of JPs for three
joint planes.
◦
◦
60 /135 , the solid rock above the given plane is represented by the great circle
marked EP in Figure 9.7(a). For the particular case of a plane horizontal roof of an
excavation, the excavation pyramid is the solid rock in the half space above the roof.
It is therefore the region inside the reference circle, as shown in Figure 9.7(b). For the
south-east vertical wall of an excavation, the solid rock is on the south-east side of the
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