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<br />- -2- <br />• -• STRENGTIi OF CAMEO "B" SEAM COAL <br />• Physical compression tests were performed an coal specimens rnred from blocks <br />of coal taken from two locations in the Roadside Mine. One location was just north <br />J of the 2nd East Section at position 10+00 along the beltline. The other location was <br />I <br />~ from just west of the 3rd East Section at position 5+00 in the 2nd Right Entry. <br />i Two uniaxial and six triaxial compression tests were run on coal from each <br />' location. Detailed test results are included in Appendix A. Five of the trioxial <br />~ compression tests performed at each location were between 200 and 1000 psi, confining <br />pressure approximating The range of depth induced confining pressures for the 2nd Gast <br />Section. One triaxial test was performed at 2000 psi confining pressure, approximating <br />the maximum depth induced stress at the Roadside Mine. These compression test <br />results are displayed on Fiqure I and presented in Table 1. <br />i , • The strength of the Cameo "B" seam coat exceeds the strength of any of the <br />western coal seartu for which test results are available, see Appendix B. The results <br />demonstrate that there is no statistical difference between the results obtained from <br />the two locations. The standard error of estimate.(Syx) for the crombined samples for <br />• confining pressures from 0 to 1000 psi is less than for either set of test results alone. <br />In addition, the level of confidence that a relationship exists between failure strength <br />and confining pressure increases for the combined samples when compared to the <br />separate sample sets. The recommended pillar design values for depths to 1000 ft are <br />0 <br />~ = 47.2 and cohesion (a a) = 783 psi. <br />The Cameo "B" seam variations in coal strength are apparently related to their <br />relative moisture contents and densities, as given in Appendix A. The samples from <br />2nd East Section were slightly weaker, slightly wetter and slightly less dense than the <br />samples from 3rd East Sectim. This agrees with the normal case for sedimentary <br /> <br />