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1 <br />' (Figure 9). Both of these two discontinuity orientations are identifiable within the <br />quarry, but have not been recorded in large enough quantities to create a strong <br />signature in the analysis of the entire dataset. However, based on the <br />prevalence of these discontinuities in the southern expansion area, both of these <br />' orientations have also been used in this analysis. <br />To adequately understand the impacts of the new data on wall stability, the <br />' planes representing each discontinuity set and the plane representing the <br />orientation of the respective quarry wall slope face were plotted on individual <br />stereonets. The stereographic analysis of each quarry wall is presented in <br />Figures 11-13 and 15-17. <br />6.2 Wedge Stability Analysis <br />As presented in earlier annual reports, the method of stereographic analysis <br />' developed by Markland (1972) was used for this study. Markland's test is <br />~~ designed to identify the possibility of a wedge failure in which sliding takes place <br />' along the line of intersection of two discontinuities (Hoek & Bray, 1977). <br />According to Markland's test, sliding can occur when: <br />1) The plunge of the lines of intersection is less than the dip of the slope face. <br />2) The plunge of the lines of intersection exceeds the angle of friction. <br />The trends of the lines of intersection that will potentially daylight onto the slope <br />' have been identified with arrows on the stereonets for each of the wall <br />orientations (Figures 11-13 and 15-17). The friction angle is drawn as a dashed <br />' circle on the stereonets at 33° based on the results discussed in Section 4. For <br />each stereonet, multiple foliation discontinuity dip angles have been utilized for <br />F-1 in order to reflect the range of realistic values expected. The alternate <br />' foliation dip angles for F-1 correspond to one standard deviation above and <br />below the mean dip angle of 36° (i.e., 46° and 26°). Markland's two criteria for <br />' potential sliding are satisfied when the intersection of the discontinuities plot on <br />_~~_ <br />