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Jtinwir.v 15. 20ON <br />Pgge <br /> <br /> <br /> 67 <br /> <br /> <br /> <br /> <br /> <br /> f` f 401W ( <br />\ J,_ • R ,?? • 1 <br /> CR <br /> 7 <br /> 071i 4.C?t S/ j <br /> <br /> <br /> <br />$ 05-G CCR <br />` <br />{--_ <br />U) 074X4-CCR <br />0 <br /> <br />Figure 3. Projection of Previous Characterization Boreholes 05-G1-CC1R through <br />05-G6-('CR to Approximate Location in Landslide <br />[loth these weak mudstone layers are known to be highly bedded layers. "The slide plane <br />of the landslide is thought to be contained in the weak L-Roof mudstone layer and that plane <br />provides a thin shear plane along the bedding. Direct shear tests are used to characterize rock <br />strength along bedding. Although multiple direct shear tests were not possible from I,-Root- <br />mudstone samples, one set of tests were performed on Q-Floor mudstone samples. It is <br />estimated tier 't'able 1 that the weak mudstones have 2011'0-5001'0 strength parallel bedding <br />compared to perpendicular to bedding. <br />The test results also suggest that there is significant difference between peak and residual <br />strengths. The residual strengths are about 40% less than measured peak strength values. This <br />can be seen by the stress-strain curve shown in Figure 4. This data is from a sample of the <br />Q-Floor mudstone from borehole 07-G17-CCR at 227 ft below collar. Similarly, there is a <br />difference between peak and residual strengths along the bedding, but the reduction is only 20% <br />less than measured peak strength values. <br />Agap ito Associates. Inc.