Stability and Reliability Analysis of the Slope of Haiqar Dam Supports Using Key Groups Method Mehdi Mokhberi (&) and Bahman Jahan Bekam Fard Department of Geotechnical Engineering, Islamic Azad University, Estahban Branch, Estahban, Iran m_mokhberi@iau.ac.ir Abstract. The study of engineering and mechanical behavior of rocks began after the collapse of jointed rocks of Vajont Dam in October 1963 in which more than 2000 people were killed. Since the dam was not damaged in this event, the overlap of engineering geology and geotechnical engineering is highly signifi- cant. Therefore, the analysis of the stability and reliability of the slope of dam stone supports, especially that of jointed stones, is one of the most important issues considered in the design of dams which is accessible through the implementation of a geotechnical model. In spite of all of the scientific devel- opments in the recent decades, this field still faces complicated problems due to the great diversity of factors affecting dam behaviors especially geotechnical conditions. Moreover, ignoring these problems can lead to project failure and great financial and human damages. One of the techniques of stability analysis is to find appropriate 3D geometrical models for rock masses including a set of simulated geotechnical blocks of masses which are formed based on topography position, the model limit, tectonic blocks, and the existing discontinuities using definite, statistical, or geotechnical methods. The findings of the present study can have significant implications in geotechnical studies for the estimation of blocks volumes and the analysis and mechanical modeling on blocks, especially the walls loss modeling and their stability analysis. Accordingly, Haiqer Reservoir Dam, located in Fars province in Iran, was analyzed in the present study. The results indicated that the left support has a low reliability and therefore, its loss risk is very high. In contrast, the left support has better stability conditions with less probable great loss risks. It was also noted that if the blocks are taken into account as a whole they can form a key group which is potentially more dangerous than a single key block. Keywords: Rock mechanics  Dam abutment  Slope stability Key groups  Block theory 1 Introduction In rock mechanics category, the Key Groups method can be employed for geotechnical engineering projects and the Key Block Analysis method can be used on geometric models with block sets. Results of limit equilibrium analysis on some blocks show that © Springer Nature Switzerland AG 2019 H. Shehata and C. S. Desai (Eds.): GeoMEast 2018, SUCI, pp. 87–100, 2019. https://doi.org/10.1007/978-3-030-01926-6_6