Laserfiche WebLink
• WHEXSI <br />111191'11 <br />luation <br />AdrianBrown <br />where: c' =effective stress cohesion of rockmass <br />~' =effective stress friction angle of rockmass <br />y =specific weight of the rockmass <br />H =height of wall <br />The ray for this parameter is drawn from the origin of the Hoek chart appropriate to the water condition <br />in the wall, and the wall slope for the desired factor of safety (generally 1.3) is computed by <br />interpolation. <br />6.3.2 Slidinc,~Wedge Method <br />In the case of the walls excavated in granitic material, the foliation planes provide the opportunity for <br />large scalethrough-going planes of weakness in the rock wall. To analyze these features, a simple planar <br />wedge was evaluated, with varying slope angles and weak plane angles, and with the measured <br />parameters for the joints established by testing. The factor of safety and probability of failure is <br />computed for each mine and weak plane geometry, and a maximum slope computed. The results of this <br />evaluation are summarized in Table 7 below. <br />Table 7 -Simple Wedge Sliding Evaluation - WHEX <br /> <br />Weak Plane: Volcanics Granites Fault Gouge <br />Water Gradient 0.1 0.1 0.1 <br />Friction(deg) 40 55 0 <br />Cohesion(psi) 31 29 40 <br />Height (ft) 455 455 455 <br />Slope (deg) 50 50 50 <br />Plane (deg) 35 35 35 <br />FOS 1.57 1.83 1.03 <br />Based on these results, slopes in granite containing through-going weak planes approach a factor of <br />safety of 1.3 when the slope is 45°, while slopes in volcanics under similar circumstances approach a <br />factor of safety of 1.3 when the slope approaches 50°. <br />6.4 Results <br />The analysis of each location with respect to stability is included in the well information presented in <br />Appendix B. The results of the slope angles that are proposed for each location are summarized in Table <br />8 below, and presented on a tentative mine map (Plate 2). <br />• <br />Report 1385L.200309017 13 <br />