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• WHEXSIopeEvaluation AdrianBrown <br />3. GEOMECHANICAL PROPERTIES <br />3.1 Density <br />A total of 12 rock core samples from two core holes drilled into the WHEX Project were tested for <br />density (ATT, 2002). Density of the granitic rocks averaged 1561b/ft3, or about 13 cubic feet per short <br />ton. Previous tests of the Cripple Creek Diatreme volcanics indicated a density of approximately 148 <br />lb/cu.ft, or about 14 cubic feet per short ton. <br />3.2 Material Strength <br />The intact strength of the materials that comprise the WHEX Mine walls has been evaluated by <br />laboratory testing. Tests were performed on samples recovered from the geotechnical coreholes drilled <br />into the wall areas of the proposed WHEX Mine. The results of the testing are presented in Appendix A, <br />and aze summarized below. <br />3.2.1 Point load testing <br />Point load tests have been, or will be performed on core from all holes drilled in the WHEX <br />geotechnical program. The data available to date is from holes GT03-02, -03, -O5, and WHC02-32. The <br />• other holes drilled are being tested during logging, which is ongoing. The results are presented in <br />Appendix A, and are summarized Table 1. <br />The unconfined compressive strength results presented in Table 1 were computed from the load test data <br />using the following relationships (Hoek and Bray, 1980): <br />IS = P/D2 <br />UCS = (14+0.175*D[mm]) * IS <br />where: P =point load (force) <br />Is =point load index (pressure) <br />D =core diameter (unit selected for IS computation determines UCS units) <br />UCS =unconfined compressive strength <br />The diameter of most core that was point load tested in this program was 2.4 inches, giving: <br />UCS = 24.7 * IS <br />This relationship has been found to be confirmed empirically for volcanic rocks in the Cresson Diatreme <br />(Brown, 1997). <br />The relationship has been used to convert point loads to UCS values, for all materials tested in the <br />program. The results for the rock types observed in the project azea (combined with prior test results for <br />diatremal rocks) are shown in Table 1. <br />• <br />Report 1385L.200309017 4 <br />