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I <br />PA <br />I <br />E <br />J <br />4P <br />I <br />I <br />I <br />I <br />4-3 <br />were considered unrealistically high (� > 34°). The coarse particles in <br />the fill can, when inadvertently included in direct shear test samples, <br />make test results unrepresentative of the mass fill. The test results <br />were not used. <br />D'Appolonia performed a triaxial test series on undisturbed material as <br />discussed in Section 2.3. The results of these tests showed the <br />following effective strength parameters: <br />- Angle of Internal Friction - 29° <br />- Cohesion - 655 psf. <br />General strength values for specific material types were also noted from <br />general soil mechanics references. <br />The rock drain comprises a comparatively small fraction of the dam cross <br />section. Data on the design gradation or strength of the in-place <br />material were not available. Based on the design specifications, the <br />drain material was assigned the following effective strength parameters: <br />- Angle of Internal Friction = 38' <br />- Cohesion - p <br />Strength properties for the foundation alluvial soils were determined <br />using available field data, direct shear test results, general material <br />correlations, and experience. The effective strength parameters <br />selected were: <br />- Angle of Internal Friction - 30° <br />- Cohesion - 0 <br />Borings in the area of the dam identify the alluvial soils as silty and <br />clayey sands and gravels. The majority of the alluvium was classified <br />