Powerhouse Cavern Estangento-Sallente - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 729

Figure 22.5 Section through powerhouse (Soria & Wittke 1985)

22.2 Site Investigation and Testing Prior to Construction

22.2.1 Site Investigation
Information on the rock types existing in the project area was obtained from the geo-
logic map (Fig. 22.6) and from mapping of outcrops at nearby slopes. Furthermore,
exploration adits had been driven. From the access adit, the portal of which is located in
the area of the outlet structure, an exploration adit branches off, which follows the axis
of the cavern and is located within the cross-section of the cavern's vault (Fig. 16.19).
From this adit core drillings had been carried out. The second adit which also runs ap-
prox. parallel to the cavern axis is located ca. 35 m west of the powerhouse (Fig. 16.19).
A drainage tunnel near the cavern invert level was excavated at an early stage of the
project and could thus also be used for exploration purposes (Figs. 16.19 and 22.4). This
tunnel was connected to the exploration adit in the cavern vault by a vertical shaft and a
crosscut. In a later phase of the project the main access tunnel to the cavern (Figs. 16.19,
22.2 and 22.4) was also excavated, which allowed additional exploration.