2015-03-11_REPORT - M1974004

• Permit No: M1974004
• IBM Index Class Name: REPORT
• Doc Date: 3/11/2015
• Doc Name: Annual Report Fee Map
• From: Martin Marietta Materials, Inc.
• To: DRMS
• Email Name: MAC
• Media Type: D
• Archive: No

Martin Marietta Materials
Spec -Agg 2015 Annual Report
1) Representative discontinuity orientations (dip and dip direction) from data collected during the
2014 site visits (Table 1).
2) Mine Slope Orientations (dip and dip direction) as presented in Table 2 and shown in Figure
2. A total of thirteen (13) slope orientations were considered.
3) Estimated Rock Mass Discontinuity Interface Friction Angle. A typical interface friction angle
of 33 degrees was considered in all cases for the kinematic analysis, as discussed in Section
6.3.
The kinematic analysis stereonet plots are presented in Figures 8 through 15. Representative
discontinuity orientations are shown as green lines. The slope orientation for the considered wall is
shown as a blue line. The friction circle is shown as a black line. Each kinematic analysis plot is
evaluated based on where discontinuities plot in relation to the "critical zone ", which is shown as a light
red shaded area on the stereonet plots.
6.4.1 Potential Failure Modes
6.4.1.1 Planar Failure
Planar failure is indicated as a potential failure mode if the dip vector of a discontinuity falls between the
dip direction of the slope face and the friction cone representing the assumed discontinuity interface
friction angle. The following four conditions, defined by Hoek & Bray (1977), must be met in order for
planar failure to occur:
1) The plane on which sliding occurs must strike parallel or nearly parallel to the slope face.
Typically, discontinuity planes with a dip direction within 30 degrees of the slope dip direction are
considered.
2) The failure plane must "daylight' in the slope face (i.e., the dip of the failure plane must be smaller
than the dip of the slope face).
3) The dip of the failure plane must be greater than the angle of friction of the plane.
4) Release surfaces, which provide negligible resistance to sliding, must be present in the rock
mass to define the lateral boundaries of the slide.
On the stereonets, criteria for planar sliding are satisfied when the dip vector of a discontinuity plots within
the critical zone, shown as shaded regions in Figures 8 through 15. The limits of the critical zone are
defined by the area of overlap between the friction circle and the great circle representing the plane of the
slope face.
6.4.1.2 Wedge Failure
Wedge failure is characterized by sliding that occurs along the line of intersection of two discontinuities
(Hoek & Bray, 1977).
According to the analysis method developed by Markland (1972), a wedge failure can occur when the
following criteria are satisfied:
1) The plunge of the lines of intersection is less than the dip of the slope face.
2) The plunge of the lines of intersection exceeds the angle of friction.
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