Static and dynamic analysis on slope stability using a DFN-DEM approach on the right abutment of the Karun 4 dam
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EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION
Earthq Eng & Eng Vib (2020) 19: 937-951
October, 2020
DOI: https://doi.org/10.1007/s11803-020-0605-7
Static and dynamic analysis on slope stability using a DFN-DEM approach on the right abutment of the Karun 4 dam Sadegh Kefayati1†, Alireza Baghbanan1‡, Masoud Torkan1†, Hamid Hashemolhosseini2‡ and Roohollah Narimani Dehnavi1† 1. Department of Mining Engineering (DME), Isfahan University of Technology (IUT), Isfahan 84156-83111, Iran 2. Department of Civil Engineering (DCE), Isfahan University of Technology (IUT), Isfahan 84156-83111, Iran
Abstract:
Uncertainty in input fracture geometric parameters during analysis of the stability of jointed rock slopes is inevitable and therefore the stochastic discrete fracture network (DFN) - distinct element method (DEM) is an efficient modeling tool. In this research, potentially unstable conditions are detected in the right abutment of the Karun 4 dam and downstream of the dam body as a case study. Two extreme states with small and relatively large block sizes are selected and a series of numerical DEM models are generated using a number of validated DFN models. Stability of the rock slope is assessed in both static and dynamic loading states. Based on the design basis earthquake (DBE) and maximum credible earthquake (MCE) expected in the dam site, histories of seismic waves are applied to analyze the stability of the slope in dynamic earthquake conditions. The results indicate that a MCE is likely to trigger sliding of rock blocks on the rock slope major joint. Furthermore, the dynamic analysis also shows a local block failure by the DBE, which can consequently lead to slope instability over the long term. According to the seismic behavior of the two models, larger blocks are prone to greater instability and are less safe against earthquakes.
Keywords: rock slope; DFN; DEM; UDEC; dynamic behavior; earthquake
1 Introduction Each year earthquakes impose excessive financial costs and lead to losses of life in different parts of the world. Iran is one of the most seismically active countries in the world, being crossed by several major faults. Earthquakes in Iran occur more often and are potentially destructive. Therefore, constructing structures adjacent to mountainous regions such as natural slopes demands further attention towards factors influencing their dynamic stability. As for main infrastructures like dams, the dynamic stability analysis of slopes located near the dam abutments being specifically prone to severe earthquakes is among the most significant engineering topics. Nowadays, various approaches including the pseudo-static method, permanent-displacement method (Newmark's method) and numerical methods are being employed for dynamic stability analysis of slopes. In pseudo-static analysis as a simple method, an earthquake is modeled as a constant force acting in the horizontal or vertical direction to the media (Terzhagi, 1950). This method suggests a safety factor about stability or Correspondence to: Alireza
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