Vol.:(0123456789) 1 3 Environmental Earth Sciences (2019) 78:621 https://doi.org/10.1007/s12665-019-8573-9 ORIGINAL ARTICLE Stability analysis of cut slopes using empirical, kinematical, numerical and limit equilibrium methods: case of old Jeddah–Mecca road (Saudi Arabia) Mehmet Sari 1 Received: 3 February 2019 / Accepted: 2 September 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract The stability of natural and man-made rock slopes has always been of great concern for engineering geology studies. To ensure a safe and functional design of excavated slopes, the frst and most crucial step is to use reliable input parameters while searching for possible failure modes at the preliminary design stage. It is highly important for practicing engineers to determine the best material property for a chosen failure criterion. This study aims to analyze the stability condition of a case road cut from diferent aspects. For this purpose, two well-known failure criteria proposed for rock masses and rock joints were applied in the study depending on the scale of the problem in the slope face. The Hoek–Brown failure criterion was used to obtain input data required for modeling intact rock and rock mass behavior, and the Barton-Bandis shear strength criterion to determine the input data necessary for the modeling of rock joint behavior. SMRTool and Dips 7.0 programs were utilized to analyze the structurally controlled instabilities due to discontinuities in the cut slope. Slide 2018 and RS2 9.0 programs were executed to examine the stability condition of cut slope subjected to circular and non-circular failures, respectively. According to the results of numerical and limit equilibrium methods, no stability problem occurred in the case of slope due to non-sliding circular or non-circular slip failures. However, according to the results of empirical and kinematical analyses, some structurally controlled sliding failure modes of planar, wedge, and toppling were expected on the slope face. The result of this study clearly shows that to reach a fnal decision, diferent analysis methods should be used to evaluate the stability of cut slopes by considering various conditions of jointed rock masses. Keywords Rock mass strength · Slope cut · Kinematic analysis · Jointed rock · Finite element analysis Introduction The stability of natural and man-made rock slopes (e.g., open pit benches, road cuts, dam abutments, and tunnel portals) has always been of great concern for engineering geology studies. Rocks as natural engineering material in these slopes exhibit considerable variations in strength and deformability both spatially and inherently. This is because they are formed as a result of various previous geological and tectonic processes. During the preliminary design of structures built in or on such rock masses, this variation must be explicitly taken into consideration. Besides, rock masses around engineering structures show signifcant variation in failure response depending on the rock structure, condition of discontinuities, and efective stresses. In case where the routes of motorways pass through these rock masses, espe- cially in mountainous regions, it is very misleading to rely on a single analysis method and material type to ensure the stability of excavated slopes. Road cuts as one of the main engineering structures built on such problematic routes, as well as viaducts, bridges, and tunnels are typical examples of this situation. To ensure a safe and functional design of cut slopes, the frst and most crucial step is to use reliable input parameters while searching for possible failure modes at the preliminary design stage. In rock mechanics literature, several failure criteria are proposed to model rock mass behavior (Hoek and Brown 1980; Yudhbir et al. 1983; Sheorey et al. 1989; Yoshida et al. 1990; Ramamurthy et al. 1988; Mehranpour et al. 2018). Besides, there are several methods proposed for stability * Mehmet Sari mehmetsari@aksaray.edu.tr 1 Department of Mining Engineering, Aksaray University, 68100 Aksaray, Turkey