One approach in definition of acceptable level of risk for slopes in hard rocks

Slope stability analysis in hard rocks is one of the most complex tasks in geotechnical engineering. It requires application of specific design principles in order to find a way to incorporate all uncertainties coming from geological, geotechnical, economic and social aspects. In the frame of this article are presented the basics of one approach that shows how is possible to link the acceptable level of risk with the values of Factor of Safety or Probability of Failure. The methodology is supported with some results from stability analyses performed for slopes on the access road to dam “Sveta Petka” in R.Macedonia and some other case histories. Based on these analyses, the article gives some new proposals in definition of acceptable (tolerable) level of risks using also criteria of probability of failure, potential loss of life and economic impacts