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REP48063
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REP48063
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Entry Properties
Last modified
8/25/2016 12:51:53 AM
Creation date
11/27/2007 12:13:15 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1974004
IBM Index Class Name
Report
Doc Date
4/15/2004
Doc Name
Slope Stability Report
From
Lafarge
To
DMG
Media Type
D
Archive
No
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6.2.2 North Walls <br />Similar to the previous L&A annual reports, the north wall has been subdivided <br />into two separate slopes for analysis: the northeast and the northwest wall. <br />The instabilities observed in the eastern section of the wall and the differing <br />slope orientations (dip directions) necessitated the distinction between the two <br />slopes. To take into account the shallower slope angle of the past three <br />benches as well as the final mine plan design, a 35° dip angle for the slope was <br />used in the analysis of each of the north walls. Also, for each stereonet multiple <br />foliation discontinuity dip angles have been utilized in order to reflect the range of <br />realistic values expected. The alternate foliation joint dip angles correspond to <br />one standard deviation above and below the mean dip angle of 37° (i.e., 48° and <br />26°). <br />As previously documented along the northeast wall, and as described in this <br />report, planar failures can occur when foliation joints, intersected by two or more <br />discontinuities, daylight in the exposed highwall. The stereonet plots prepared <br />for the northeast wall (Figure 11) and the northwest wall (Figure12) indicate a <br />possibility for planar failure along the foliation plane (refer to previous section for <br />the four criteria for planar sliding). Each of the stereonet plots prepared <br />indicated that intersections between discontinuities F-1 and P-2 and F-1 and P-3 <br />will occur, and each of the intersections fall very close to or within the daylighting <br />envelope. In addition, in the stereonet plot for the northeast wall, the dip <br />direction of the F-1 plane falls between the dip direction of the slope face and the <br />trend of the line of intersection formed by F-1 and P-2; therefore indicating that <br />planar failure along F-1 is possible. <br />To further investigate the impact of the foliation on the stability of both the <br />northeast and northwest walls, the discontinuity data collected to date that <br />contains elevation information for the foliation orientation were plotted on a chart <br />showing dip versus elevation (Figure 13). The plot indicates that there is a <br />significant percentage of "shallower than 37°" dipping foliation planes that start at <br />an elevation of 6,325 feet and continue to below the planned final pit elevation. <br />-16- <br />
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