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Geotechnical Evaluation of Mine-Induced Earthquakes on Bruce Park Dam <br />Bowie Resources, Limited <br />June 2002 <br />identified as new embankment, old embankment, foundation soils (glacial deposits), and <br />bedrock as described in the aforementioned report. New embankment materials are <br />associated with an embankment raise completed in 1952 and old embankment materials are <br />associated with the original construction of the dam in 1940. The representative section had <br />a 16-foot-wide crest with 3H:1 V and ;.5H:1 V upstream and downstream slopes, <br />respectively. The representative section used in the pseudo-static analysis is presented on <br />Figure 3.1. <br />3.4 Representative Cross Section for SHAKE Analysis <br />We used a vertical section through the crest of the dam, which is consistent with a vertical <br />section through Figure 3.1 to develop the one-dimensional model for the SHAKE analysis. <br />The one-dimensional model used for the SHAKE analysis is shown on Figure 3.2. . <br />3.5 Water Pressures <br />Water pressures through the dam and foundation were estimated based on the following: <br />• full reservoir and steady state seepage with the reservoir at normal pool, which is 6 <br />feet below the crest of the dam <br />• the embankment is homogeneous and isotropic because it has no internal drainage <br />systems <br />• the phreatic surface would exit the downstream slope above the toe of the dam and <br />can be estimated using the Casagrande's solution (Casagrande, 1940) <br />It is our opinion that these assumptions are very conservative because seepage has not been <br />observed on the downstream slope and based on the typical operation of the reservoir, <br />saturation of the embankment is unlikely. <br />3.6 Material Properties <br />Material properties, such as moist and saturated unit weights, shear strengths, and maximum <br />shear moduli for different soil types were estimated based on: 1) results from laboratory tests <br />(GEI 2001), 2) published empirical correlations, and 3) our experience in geotechnical <br />engineering. <br />Static undrained shear strengths of new embankment, old embankment, and foundation soils <br />were based on undrained strength versus consolidation stress plots (Figures C.2, CA, and C.6 <br />from GEI, 2001), which are provided in Appendix A for reference. <br />11 <br />02-05-:: Geotechnical Evaluation of Mine-Induced Earthquakes <br />GEI Consultants, Inc. 8