Powerhouse Cavern Estangento-Sallente - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 731

Figure 22.7 Pole plot of discontinuities mapped in the exploration adits (Soria & Wittke 1985)
Four of the mapped master joints and very few further discontinuities intersect the
cavern axis approximately at right angles. These were classifi ed as a further set D4. The
mapped discontinuities of set D4 are not represented in the pole plot in Fig. 22.7 (left).
Furthermore, two larger discontinuities striking approximately parallel to the cavern
axis and dipping steeply to east and west were mapped in the access adit at larger dis-
tance from the cavern. Since very few smaller discontinuities of these orientations were
mapped, these discontinuities assigned to sets named D3 and D3' were also not entered
in the pole plots represented in Fig. 22.7.
Within the granite the same discontinuity sets as in the metamorphic rock were encoun-
tered.
22.2.3 Testing
During the design phase an extensive rock mechanical testing program was performed,
including uniaxial and triaxial compression tests, Brazilian tests, LFJ tests, dilatometer
tests and triaxial cell stress measurements (Chapters 14, 15 and 16). The locations where
the fi eld tests were carried out are shown in Fig. 16.19.
Relatively large unconfi ned compressive strengths of 80 - 200 MPa were obtained for
the metamorphic rock, the mean value being c = 150 MPa. Also the unconfi ned com-
pressive strength of the granite was found to be very large.