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Table2-Deere's engineering classification for intact rock. <br />Class Description Uniaxial compressive strength, psi <br />A Very high strength <br />B High strength <br />C Medium strength <br />D :Low strength <br />E Very low strength <br />On the basis of modulus ratio <br />Class Description <br />H High modulus ratio <br />M Medium modulus ratio <br />L Low modulus ratio <br />>32,000 <br />16,000-32,000 <br />8,000-16,000 <br />4,000-8,000 <br /><4,000 <br />Modulus ratio <br />>500 <br />200-500 <br /><200 <br />The point load tests complemented the uniaxial compressive strength results by providing <br />additional data in a cost-effective manner. Because many of the axial point load tests <br />were obtained very close to where measurements of uniaxial compressive strength were <br />collected, it is possible to correlate test results. As illustrated in figure 5, the data is <br />scattered around a one-to-one ratio line. There is a fair correlation between point load <br />and UCI test results with linear regression coefficient (R) of .61. <br />UCS vs Axial Point Load Strength <br />30000 <br />25000 <br />20000 <br />a <br />15000 <br />0 <br />0 <br />pn <br />Q <br />10000 <br />5000 <br />0 <br />0 <br /> <br />? 1:1 Line <br />• <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />5000 10000 15000 20000 25000 30000 <br />Uniaxial compressive strength, psi <br />Figure 5. Uniaxial compressive strength vs. axial point-load test results. <br />E <br /> <br />0 <br />Maleki Technologies, Inc. Page 15