REP48063 - Laserfiche WebLink

Home Browse Search

analyses. This approach of using ~ + i to represent the friction angle of the rock differs from the Mohr Coulomb strength criterion utilized in the 2003 geotechnical investigation and slope stability analysis, but is utilized due to the geometric input constraints of the stereonet and the wedge stability analysis used in this study. The Mohr Coulomb approach includes both a friction angle and a cohesion value to define the shear strength of the discontinuities, where the cohesion value is used to account for'Yhe interlocking of asperities on the matching surfaces of the joint, and the increase in shear strength given by this interlocking..." (Hoek, 2000). 5.0 Field Observations In addition to the field data collected, the following field observations were also used to assess the current quarry conditions: ' 1) Significant mining progress has occurred in the quarry since the previous annual report was prepared (Li3iA, 2002). Most notable is the new access/haulage road (Photo1), and excavation and reclamation of the initial two 20-foot benches in the southern expansion area (Photo 2). The third and fourth benches (each 35 feet high) are also currently being excavated. These benches are being excavated in two lifts, each approximately 17-18 feet high. Rock exposures on advancing benches were mapped for east, southeast, northeast and north facing exposures in this area. The middle level has also been extensively mined since the 2002 annual report with the average elevation of the entire bench being approximately 100 ft lower (Figure 2, Photo 3). Currently, the middle level is being excavated to the 6,480-foot elevation, and rock exposures on advancing faces were mapped for north, east, west and south facing wall orientations at this level. In the main pit, the base elevation of 6,340-feet has not changed since the 2002 annual report was prepared. Some mining has continued in the -7-