Abstract At the Sarcheshmeh mine, the design and stability analysis is very critical due to the existence of major features such as faults and dikes, and relation of various joint sets with the geometrical form of the pit. Western area of Sarcheshmeh mine includes various types of failures, commonly structural failure type such as Sarcheshmeh pseudowedge failure. This type of failure consists of large and weak blocks of weathered highly jointed andesite surrounded by a fault and important joints. Existence and extension of near parallel faults filled with pyrite-clay in the western wall of Sarcheshmeh mine along with the geometry of this wall results in special slide conditions which need to be considered during mine expansion project. There are some limitations in using limit equilibrium methods to analyze this type of sliding. This paper analyzes Sarcheshmeh pseudowedge failure using three dimensional distinct elements method. The influence of effective parameters on the stability of such failures is quantitatively calculated and proper solutions are discussed. 1. Introduction The Sarcheshmeh porphyry copper-molybdenum deposit is located in southern Iran, at 30 degree N lat., 56 degree E long. It is currently the largest open pit mine in Iran. Western area of Sarcheshmeh mine includes various types of failures, commonly structural failure type such as Sarcheshmeh pseudowedge failure. This type of failure consists of large and weak blocks of weathered highly jointed andesite. Due to intersect of a fault with the rock mass surrounding the walls of this area (figure 1), various wedge-like rocks have been progressively sliding on the fault plane [1]. Sarcheshmeh mine is being expanded as a result of cut off grade reduction. Existence and extension of near parallel faults has made pseudowedge failure a new challenge in expanding western area of Sarcheshmeh mine. Most parts of this rare failure are kinematically stable but they will become instable with time and therefore they can not be kinematically analyzed. In limit equilibrium analysis, the stability is investigated regardless of its relation with displacements and safety factor is calculated based on static condition. Therefore, when displacements occur in a slope, limit equilibrium methods are not suitable to evaluate the effect of such displacements on total stability of the slope [2]. An example of such analysis has been done on Sarcheshmeh pseudowedge failure [3]. Numerical methods are available to analyze and model this phenomenon according to observations. This paper analyzes Sarcheshmeh pseudowedge failure using three-dimensional distinct elements method. The influence of effective parameters on the stability of such failure is quantitatively calculated and proper solutions are discussed. 2. Geological Settings Porphyry ores, such as Sarcheshmeh, are the most complex geological environments in terms of fracturing. The Sarcheshmeh deposit is related to the Late Tertiary granodioritic stock which intruded the early Tertiary volcanics. The deposit 560 was intruded by intra-mineralization and post mineralization dikes and intrusives [4].