Stabilization of a Rock Mass Slide - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 817

Figure 25.25 Increase in anchor loads, comparison of measured and calculated loads

25.4 Installation of Additional Tendons

Although the slope was stable, for long-term stability a safety factor of 1.2 was re-
quired. Also, a maximum admissible anchor load of 805 kN was specified. This cor-
responds to the load above which stress cracking corrosion may occur (Fig. 25.19).
The tendons located in the area surrounded by the red contour line in Fig. 25.19 on
which this force has been exceeded were released by removing the spacer disk that
was inserted during installation. By this means, the anchor force of these tendons was
reduced by 95 kN. Thus, an additional anchor force of n · 95 kN was required for the
stabilization of the slope, where n is the number of tendons with an anchor force of
F A > 805 kN . For this purpose, 21 additional tendons were installed. Supplementary
tendons were installed for those tendons on which even after removing the spacer disk
an anchor force of F A > 805 kN was measured. The installation of the overall 135
additional and supplementary tendons was completed in summer 2005 (Rensing &
Pierau 2006, Fig. 25.26).