2015-03-11_REPORT - M1974004 - Laserfiche WebLink

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Martin Marietta Materials Spec -Agg 2015 Annual Report 6.0 ANALYSIS OF STRUCTURAL DISCONTINUITIES The stability of the rock mass that forms the quarry walls is primarily controlled by the presence of rock discontinuities, such as joints, foliation, and faults. Discontinuities can create surfaces for sliding, and the intersections of multiple discontinuities can define the boundaries of wedges or blocks that have the potential to slide. The orientations of discontinuity sets vary considerably throughout the quarry. Therefore, it is possible that discontinuity orientations in a specific location of the quarry could deviate from the discontinuity orientations assumed for the analyses presented in this report. 6.1 Evaluation of Discontinuity Measurements Representative discontinuity orientations for the quarry walls are required in order to evaluate the stability of the rock mass that forms the mine walls. Representative orientations for each discontinuity set observed were developed by analyzing the thousands of measurements collected since the beginning of the project. For the 2015 annual report, we evaluated how the data collected over the past year compares with the previous geologic structure dataset and the representative orientations of observed discontinuity sets previously selected for analysis. Using this approach, we are able to assess possible emerging trends related to the shift in orientation of the various observed discontinuity sets as more of the rock mass is exposed during mining operations. Our structural discontinuity analysis for the 2015 annual report is based on the updated representative discontinuity orientations that includes the data collected this year. We analyzed the discontinuity orientation data using DIPS 6.016 (Rocscience, 2014). The program enables plotting of individual data points, and offers several methods of data analysis, including contouring or cluster analysis. We plotted the individual data points collected during the June and December 2014 site visits over contours for the entire dataset, and alongside representative discontinuity orientations used for the 2014 annual report (Figure 5). In general, the data collected during our recent visits is consistent with the representative orientations of discontinuity sets observed in previous years, with a few exceptions. These exceptions include: 1) Joint set P -5 was observed again this year, 2) the absence of F -3 identified in the previous report (prior to 2013), 3) the new representative joint set (P -7) identified in the 2013 annual report was again observed, and 4) the observation of new foliations which may be localized and will need further observation during next year's study (Figure 6). We plotted and contoured individual data points from the 2014 site visits to help visualize the clustering of data from the recent measurements and to develop representative discontinuity orientations for use in kinematic analyses performed as part of this annual report (Figure 6). Individual data points are plotted by area (Main Pit versus Southern Expansion Area) to assist in evaluating whether some of the data trends are location specific. Representative discontinuity orientations of the nine (9) previously recognized discontinuity sets from the 2013 and 2014 annual reports are shown for comparison. As shown in Figure 6, there is general consistency between the representative discontinuity orientations previously used for the structural discontinuity analysis and the contour peaks based on clustering of the new data, with some notable differences. We did not measure discontinuities this year that are representative of previously recognized foliation F -3. Arrows shown in Figure 6 indicate the apparent February 25, 2015 Page 8 Lachel & Associates, Inc. Project 14364006 00 ©2015 All Rights Reserved