Laserfiche WebLink
<br />' addition, as discussed in the previous section, an east-west striking unnamed <br />fault zone is mapped in the northwest corner of the main pit. With the <br />combination of faulting and discontinuities on the north walls, the potential <br />impact on the slope stability should be closely monitored as mining continues. <br /> 6.2.3 West Walls <br /> No mayor stability issues currently exist for the west walls of the main pit or <br />' middle level of the quarry. Previous analysis indicated that the west highwalls <br /> have approximately the optimum orientations for stability. Two west wall <br /> orientations were analyzed in this study. The first had a dip direction of 091 °, <br /> and using this orientation the stereonet plot (Figure 13) indicated two plunges of <br />' line intersections less than the angle of the slope face, and one intersecting set <br /> of discontinuities that is within the failure envelope. Two of the intersections <br /> were at angles lower than the critical friction angle and indicate that sliding along <br /> these surfaces is possible but unlikely. For the set that is within the failure <br /> envelope (i.e. P-1 and P-6) sliding is assumed to occur because the plunge of <br /> the line of intersection slightly exceeds the 33° angle of friction. <br /> <br /> The second western wall analyzed in this study, has a dip direction of 120° <br />t (Figure 13). The results for this analysis yielded fairly comparable results, with <br /> two intersecting planes falling outside the failure envelope and one set mapped <br />' within. The intersection of discontinuities F-1 and P-2 fall just within the shaded <br /> region and sliding is assumed to occur as the plunge of the line of intersection <br /> exceeds the 33° angle of friction. <br />6.2.4 South Walls <br />As with the north wall and west wall, the southern wall has also been subdivided <br />into separate slopes for analysis: two southwest walls and a southeast wall <br />orientation were selected based on the proposed Lafarge mine plan (Lafarge, <br />2003). This approach is the same as was used for the 2004 annual report, in <br />-21 -