One approach for design and construction of slopes in andesitic rocks prone to deterioration

This paper presents an approach applied in the design and construction of one cut at the section km
24+740 - km 24+960 from the expressway A4, section Stip – Radovish, a part of the Macedonian road
network in construction. The road in some zones is constructed in hydrothermally modified rock mass
of andesitic type, with complex geological structure and alternation of different zones within the
massif, prone to deterioration. In the frame of this article, the approach based on the integral
application of empirical – analytical, and observational methods during the design and construction is
presented. Some results from investigations and correlations between the investigated parameters
necessary to define optimal elements of the slope are also given. The complexity of the problem,
requiring consideration and inclusion of many factors in the analysis and the degree of uncertainty of
the input parameters, especially in zones of rock masses prone to weathering and deterioration, is
pointed out. The example indicates that sometimes it is almost impossible to fully predict all
geotechnical and construction aspects in the initial stages of research and design. It is noted that every
engineering problem is a unique challenge, which requires the cooperation of all parties involved in
investigation, design, and investment in capital projects. In this regard, some recommendations on the
acceptable values of the factor of safety and probability of failure, in the context of the rank of the
object are presented.