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2. Laboratory Results <br />I Twenty-six drill core samples from various depths of five holes were tested <br />by F. M. Fox and Associates in Denver, Colorado. The results of the core <br />testing programs are summarized as follows: <br />` Uniaxial Indirect <br />Specific Unit Compressive Tensile <br />Rock Gravity Weight Strength Strength <br />Sandstone 2.55 143.7 pcf 10,425 psi 664 psi <br />Siltstone 2.42 135.3 3,310 389 <br />Shale 2.51 147.9 9.952 520 <br />` Coal* 1.48 76.0 2,240 162 <br />{ *Most of the coal had been removed from the core boxes prior to our <br />111 study. The core tested as coal was taken from the remainder and may <br />i not be representative. <br />1 <br />Four soil samples of three different types of soil taken from the out- <br />crops were tested at id. A. Wahler and Associates' laboratory, the results <br />ttt of which are given below: <br />Triaxial Shear Strength <br />~. Specific Total Stress Effective Stress <br />Material Gravity Cohesion Friction Cohesion Friction <br />leathered shale 2.71 5.0 psi 10.5° 0 psi 35.So <br />Decomposed shale 2.72 4.5 15.0 1.8 32.5 <br />Clay 2.71 9.2 14.5 3.8 33.5 <br />L 3. Stability Analyses <br />L The general geology of the area and the laboratory test results Indic fed <br />that a "wedge analysis" would be the most appropriate for the stability <br />analysis. A total of six combinations of two slope heights and three <br />L slope angles were analyzed using a conventional wedge analysis. In the <br />analyses of the design slopes, the average values of effective and total <br />stress strength parameters of soil were used as tl~e limiting strength <br />of the jointed rock mass, assuming the failure will occur along sets of <br />4 joints and bedding planes. Water was assumed to exist seasonally in each <br />'• of the coal seams. <br />W AWRHIER Project 0807 III-2 <br />L & assoc~~ <br />