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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />002654 <br /> <br />Shear Strength. <br /> <br /> <br />In order to analyze the stability of the proposed dam, the shear <br /> <br /> <br />strength characteristics of the 3 materials involved were required. <br /> <br /> <br />Undrained, consolidated, saturated, triaxial shear tests with pore <br /> <br /> <br />pressure measurements were performed on representative samples of <br /> <br /> <br />the foundation, Zone 1 and Zone 2 material as discussed above. The <br /> <br /> <br />foundation material was remolded to approximately 121 p.c.f. dry <br /> <br /> <br />density to represent the approximate average in-place density as <br /> <br /> <br />determined in the test pits using a nuclear density gauge. The <br /> <br /> <br />main borrow area material was remolded to approximately 118.5 p,c.f. <br /> <br /> <br />dry density to reflect roughly 95% standard proctor density (ASTM <br /> <br /> <br />D-698). The clay shale material, representative of the left abut- <br /> <br /> <br />ment, spillway area, and Zone 1 embankment, was remolded to 114 <br /> <br /> <br />p.c.f. dry density to approximate both in-place density on the left <br /> <br /> <br />abutment and roughly 95% standard proctor density since the abutment <br /> <br /> <br />material was actually more dense than 95% in place. All materials <br /> <br /> <br />involved are gravelly, with particles much too large to practically <br /> <br /> <br />include in a triaxial sample. The samples were therefore reblended <br /> <br /> <br />to closely represent the material to be used. The results of the <br /> <br /> <br />triaxial tests are presented in APPENDIX C. As can be seen, these <br /> <br /> <br />GC soils possess good shear strength as indicated by the moderate <br />cohesive strengths which accompany the relatively high angles of <br />internal friction. This material will not only provide good stab- <br />ility in the dam embankment, but also in the foundation and abut- <br />ments due to the high in-place densities encountered. <br /> <br />Downstream Slope Stability. <br /> <br />The stability of the downstream slope of the dam was analyzed using <br /> <br />the effective stress soil shear strengths for each material involved <br /> <br />-3- <br /> <br />~ .~ <br />