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Martin Marietta Materials <br />Spec -Agg 2014 Annual Report <br />1) Representative discontinuity orientations (dip and dip direction) from data collected during the <br />November 2013 and March 2014 (Table 1). <br />2) Mine Slope Orientations (dip and dip direction) as presented in Table 2 and shown in Figure <br />2. A total of thirteen (13) slope orientations were considered. <br />3) Estimated Rock Mass Discontinuity Interface Friction Angle. A typical interface friction angle <br />of 33 degrees was considered in all cases for the kinematic analysis, as discussed in Section <br />6.3. <br />The kinematic analysis stereonet plots are presented in Figures 8 through 15. Representative <br />discontinuity orientations are shown as green lines. The slope orientation for the considered wall is <br />shown as a blue line. The friction circle is shown as a black line. Each kinematic analysis plot is <br />evaluated based on where discontinuities plot in relation to the "critical zone ", which is shown as a light <br />red shaded area on the stereonet plots. <br />6.4.1 Potential Failure Modes <br />6.4.1.1 Planar Failure <br />Planar failure is indicated as a potential failure mode if the dip vector of a discontinuity falls between the <br />dip direction of the slope face and the friction cone representing the assumed discontinuity interface <br />friction angle. The following four conditions, defined by Hoek & Bray (1977), must be met in order for <br />planar failure to occur: <br />1) The plane on which sliding occurs must strike parallel or nearly parallel to the slope face. <br />Typically, discontinuity planes with a dip direction within 30 degrees of the slope dip direction are <br />considered. <br />2) The failure plane must "daylight' in the slope face (i.e., the dip of the failure plane must be smaller <br />than the dip of the slope face). <br />3) The dip of the failure plane must be greater than the angle of friction of the plane. <br />4) Release surfaces, which provide negligible resistance to sliding, must be present in the rock <br />mass to define the lateral boundaries of the slide. <br />On the stereonets, criteria for planar sliding are satisfied when the dip vector of a discontinuity plots within <br />the critical zone, shown as shaded regions in Figures 8 through 15. The limits of the critical zone are <br />defined by the area of overlap between the friction circle and the great circle representing the plane of the <br />slope face. <br />6.4.1.2 Wedge Failure <br />Wedge failure is characterized by sliding that occurs along the line of intersection of two discontinuities <br />(Hoek & Bray, 1977). <br />March 31, 2014 Page 11 Lachel & Associates, Inc. <br />Project 13364013.00 02014 All Rights Reserved <br />