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1 <br />1 <br />1 <br /> <br /> <br />t <br />1 <br />i <br /> <br /> <br /> <br />t <br />1 <br />1 <br />1 <br /> <br /> <br /> <br />highest slope configuration and, therefore, its <br />configuration was used for the slope stability analysis. <br />Two cases of shear strength parameters were used in the <br />stability analysis. One case assumed the typical shear <br />strength parameters determined by the method described <br />elsewhere in this report, while the other case assumed a <br />"worst case" where all bedrock materials were assumed to <br />have the weakest shear properties associated with the <br />shales. The results of the analysis indicates that the <br />rock in the vicinity of the portals can be excavated to <br />0.5 vertical to 1.0 horizontal and have a safety factor <br />greater than 1.5 for all cases. <br />• Non-Circular Rock f,Yy~ Failure: The non-circular rock <br />failure analysis indicated that there is no potential for <br />massive planar, wedge or toppling failures to occur at <br />the proposed rock cuts. This is mainly the result of the <br />0 <br />general orientation of the bedrock (NS E) with its dip of <br />five to 10 degree slope into the slope rather than <br />exiting from the slope and the relative perpendicular <br />orientation of the joints. <br />• Aench Failure Modes: Figure 17 indicated that Case A <br />will have the highest bench elevation among all the <br />proposed alternatives. Therefore, this case was analyzed <br />for its slope stability. The results of the stability <br />analysis indicated that the proposed bench will have a <br />factor of safety greater than 1.5. <br />13 <br />