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6.0 Analysis of Structural Discontinuities <br />The stability of the rock mass that form the highwalls of the quarry is controlled <br />by the discontinuities that exist within the rock mass. When the discontinuities <br />intersect, wedges and blocks of various sizes develop and create the surfaces <br />along which sliding can occur. As observed throughout the quarry, the <br />discontinuities all have a range of dip and dip direction, and therefore it is <br />possible that occasional discontinuity orientations in a specific location of the <br />quarry deviate from the general discontinuity orientations assumed for this <br />report. <br />6.1 Evaluation of Discontinuity Measurements <br />^ As the database for discontinuity measurements has increased, various methods <br />' have been utilized to efficiently analyze the new geologic data relative to the <br />existing data. For this study, the data were evaluated with stereographic plots <br />' using a combination of contour analyses and cluster analyses to determine <br />representative dip directions and dip angles for the predominant discontinuities. <br />1 The contour analysis of the entire dataset (i.e., 2,716 points) resulted in a plot of <br />density contours which facilitated determination of the primary discontinuity <br />' orientations (Figure 6). The cluster analysis further refined the data by utilizing <br />an iterative approach to group the data measurements into representative <br />clusters. The nucleus of each cluster represents the concentration center for the <br />cluster (Figure 7). The differences between each of the year's analyses can best <br />be seen on a stereographic presentation showing all of the concentration poles <br />for the clusters for multiple years analyses (Figure 8). A combination of the <br />' clusters from Figure 8 and the results of the contour and cluster analysis of the <br />entire dataset were used to define the discontinuities and their orientations for us <br />' in this year's analysis. The poles representing these discontinuities are <br />presented in Figure 9, and are further detailed in Table 2. <br />1 _,Z_ <br />