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Martin Marietta Materials <br /> Spec-Agg 2016 Annual Report <br /> 6.3 Friction Angle <br /> A representative angle of friction (� + i) = 330 was used for our kinematic analysis, where"�" is the basic <br /> friction angle and 'T is the surface roughness angle (Hoek and Bray, 1977). The surface roughness <br /> angle is the angle between the basic plane of the joint and the planes representing the surface of <br /> undulations on the joint surface. This value was based on the results of the direct shear testing <br /> performed as part of the 2003 geotechnical investigation (Lachel, 2003). The test results produced only a <br /> basic friction angle, �, and results indicated that the basic friction angle of the discontinuities ranged from <br /> 13.70 to 49.30 with a mean value of 280. These results do not include the two direct shear tests <br /> conducted on samples with clay material along the foliation plane, which produced an average friction <br /> angle of 5°. A generally accepted and conservative value of 50 was selected for the surface roughness <br /> angle, 'T. <br /> 6.4 Kinematic Analysis <br /> We performed kinematic structural discontinuity analyses for each of the representative quarry wall <br /> orientations presented in Table 2. The analyses were performed to evaluate potential rock slope failure <br /> modes controlled by planar rock mass discontinues based exclusively on the geometric relationships of <br /> the discontinuities measured. Potential rock slope failure modes include sliding of wedges formed in the <br /> slope by the intersection of two discontinuity planes, sliding of rock blocks along a single planar <br /> discontinuity, and toppling rock blocks. The computer program DIPS 6.017 (Rocscience, 2015) was used <br /> for the kinematic stability analysis. Inputs for the analyses include the following: <br /> 1) Representative discontinuity orientations (dip and dip direction) from data collected during the <br /> 2015 site visits (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 /> February 8,2016 Page 7 Lachel & Associates, Inc. <br /> Project 15364004.00 ©2016 All Rights Reserved <br />