Powerhouse Cavern Estangento-Sallente - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 743

cable tunnel and both the upstream and downstream manifolds. Both figures indicate
that individual joints of these sets extend for some considerable distance.
Figure 22.19 Mapping of cavern, developed view (Soria & Wittke 1985)
The monitored displacements resulting from excavation of benches III to IX (extensom-
eters E-10, E-30, E-43, E-53 and convergence measuring cross-sections C-4, C-22, C-43,
C-56) are represented in Figs. 22.21 and 22.22. The displacements measured with exten-
someters were related to the anchoring points farthest from the cavern. They may indi-
cate the extent of the disturbed or loosened rock zone around the cavern (e.g. E-10(2) in
Fig. 22.21 and E-43 in Fig. 22.22). In convergence measuring cross-sections C-22, C-43
and C-53 approximately equal horizontal wall displacements were monitored with a
maximum of 30 mm. These displacements were considerably larger than those monitored
in cross-section C-4, which is located near the end wall of the cavern, reflecting three-
dimensional effects. All measured displacements increased with advancing excavation.