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Análisis probabilístico de la estabilidad de la ladera derecha sobre el vertedero de la presa de la Central Mazar

Abstract:

The analysis of slopes for balance limit it is common to set the safety factor as an indicator of stability, being determined by the relationship between the forces and / or resistant moments versus the acting. Generally the analysis considers the layers of soil and / or mass rock as homogeneous and geotechnical parameters constant. Instead, the probabilistic analysis, considers the uncertainty in the determination of geotechnical parameters assumed and the natural heterogeneity that rock masses have. Based on the slope analysis using limit equilibrium, it is common to establish the safety factor as the stability indicator, which is determined by the relation between forces and /or resistant moments versus acting forces. The analysis, generally, considers the layers of the soil and/or rock mass as homogenous and with constant geotechnical parameters. However, the probabilistic analysis, considers the uncertainty in determining assumed geotechnical parameters, and the natural heterogeneity that rock mass contains. The analyzed slope is located near the Mazar Hydroelectric dumping ground, in Azuay province. This power plant is part of Paute’s Integral Hydroelectric Project, which is fundamental for Ecuador’s development. The slope was typified with data obtained prior the damn construction as well as from monitoring done after the construction. The criteria applied for the slope stability analysis are as follows: the rupture takes place in the rock mass, geological fault has a planar origin, and it is based on the Mohr Coulomb criterion. On the probabilistic analysis, geotechnical parameters of internal friction and rock cohesion were varied. The results highlight the importance the variation of mechanical parameters of the ground and the sample distribution has on the slope stability analysis. The stability analysis showed that the probability for the slope to meet the safety design factor, i.e. greater that 1.3, is 99.94%.