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1 <br />' The most dominant and critical structure was awest -east trending feature dipping moderately to <br />the south. This was also observed in the East Pi[ mapping and showed joint lengths ranging <br />between 50 - 100 feet. The exposure within the East Pit indicated that the remaining joint sets were <br />' less than 20 feet in length. In additicn to joint orientations, the following were recorded; <br />1. Type of structure <br />(' 2. Discontinuity size. Determined through pit mapping or implied by structure type when drill <br />' core was only was available. <br />3. Infill characteristics. This was described by the joint alteration. The Pink Gneiss was <br />' ~ highly chlorite-clay altered, whereas joints in the Biotite Gneiss exhibited only slight <br />alteration to unaltered joint walls. <br />' 4. Water. <br />' S. Joint Roughness: The degree of surface roughness was recorded for the individual <br />' structures as outlined in Figure 6 and Appendix I. <br />' It was observed in cell mapping of the Biotfte Gneiss in the East Pit that a moderate <br />(JRC=10) joint roughness was recorded as shown in Figure 9. <br />' 6. Intact Rock Strength: This was determined primarily through point load testing on drill <br />core and using field index tests as described in Table 2. The Biotite Gneiss exhibited <br />strengths exceeding a field index of R3 (7500 - 15000 psi) and an average unconfined <br />compressive strength (UCS) as estimated through poirn load testing of 9!00 psi. The <br />Santa Fe, Pink Gneiss and Green Ciay materials exhibited field strength values below an <br />S5 (under 150 psi). This is shown in Figure 10. <br />The structures within the Biotite Gneiss showed similar joint populations, Figure 6. However, for <br />' mine design purposes, the discontinuities mapped within a particular structural domain were <br />employed for the design of that sector rather than grouping data from all drill holes together onto <br />one stereonet. <br />5.0 MINE DESIGN <br />' The structural domains are areas exhibiting similar geotechnical characteristics. If the mine plan is <br />superimposed upon the domains we can delineate mine sectors, where slope angles have to be <br />assessed wRh respect to the variance in wall trend. In addition, slope angles wthin Individual mine <br />sectors are influenced by ultimate slope heights, the implications of failure and sequence of <br />extraction. <br />1 <br />1 <br /> <br />