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schematic drawings illustrating the types of failure anticipated. Analysis of these <br /> potential failures is based upon techniques of stereographic projection discussed by Hoek <br /> and Bray (1977). <br /> 4.4.1 Intermediate Scale Stability <br /> A number of small faults, mapped in Bench 1, have been identified and have the <br /> potential to create wedges of intermediate size. The faults have a linear continuity of <br /> several hundreds of feet and clay gouge fillings up to 1 inch thick. <br /> The potential for wedge formation is shown graphically in Figures 4.4 and 4.5, <br /> where the plunge and plunge direction of the wedge intersection is plotted in lower <br /> hemisphere stereographic projection. The two figures also show the strike and dip of the <br /> composite pit wall for the north, south, and east walls. A friction circle for the coefficient <br /> of friction of thick, clay gouge 12°) was superimposed on the stereonet and defines <br /> the shaded area where: <br /> • the plunge of the structural feature is less than the composite slope angle and, <br /> therefore, it is kinematically possible for the wedge to slide out of the slope; <br /> and <br /> • the frictional resistance along the fault planes is less than shear force causing <br /> the wedge to slide. <br /> The wedge intersections that plot in the shaded area can fail should their spatial locations <br /> coincide with the pit slope in a way that allows the wedge to develop. <br /> Figure 4.4 shows that the potential for the mapped faults to form wedges in the <br /> north wall is limited to Il_6. The two faults, F1 and F6, are located at opposite ends of <br /> Bench 1, and the actual point of location does not lie within the pit. <br /> A total of five potential intersections occur for the south wall and two potential <br /> intersections occur for the east wall. Plane failures on F3 and F5 are also possible on the <br /> south wall if these fault structures, mapped on Bench 1 of the north wall, are typical of <br /> the southern area of the pit. <br /> 16 <br />