Uncertainties and Complexities of the Geological Model in Slope Stability: a Case Study of Sabzkuh Tunnel

Abstract

Slope stability analysis is a geotechnical engineering problem characterized by many sources of<br />uncertainty. In slope stability computations, some of these sources are encountered, such as geological<br />details missed in the exploration program, estimation of soil properties that are difficult to quantify<br />and many other relevant factors. Therefore, accurate reproduction of the spatial variability in the field<br />could be essential to decrease uncertainty. The Sabzkuh-Choghakhor water conveyance tunnel is<br />currently under construction using the NATM and TBM tunnelling methods in the Zagros Mountains<br />in south-western Iran. In the slope stability assessment of the Sabzkuh tunnel portal, despite adequate<br />geotechnical investigations, field studies have not been performed with appropriate accuracy. A<br />landslide and collapse has occurred in a part of the portal due to tunnel excavation. In this paper, the<br />importance of having a precise and predetermined schedule for selecting site location, monitoring,<br />complexities of the geological model, uncertainty and its effects on the stability of the trench were<br />investigated and the necessity of comprehensive slope management was emphasized.