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<br />~1 <br />I <br />4.5.2 Displacement Analyses <br />San Luu Mine - ['hose Q, Raise 1 Design Report <br />' 4.5.2.1 Background <br />Although pseudostatic stability analyses similar to those presented in the Amendment demonstrate <br />' adequate stability, dynamic deformation analyses, developed to more accurately predict the behavior <br />of an embankment during an earthquake, have also been conducted to confirm that the structure will <br />' be stable. Newmark (1965) proposed a method of dynamic analysis of potential failure surfaces <br />within an embankment analogous to a block resting on an inclined plane. If an acceleration pulse <br />results in an inertia force which when coupled with stale shear stresses is fazge enough to overcome <br />' the resisting force, the block will slide down the plane until the acceleration reduces sufficiently for <br />the resisting forces to be lazger than the combined inertia and static forces. For a series of <br />acceleration pulses, such as from an earthquake, the total displacement of the block down the plane <br />will be the sum of the displacements which occur during each pulse producing inertia forces greater <br />than the available resisting forces. <br />Newmark utilized four earthquake strong motion records to determine the effective number of pulses <br />in an actual earthquake. He then normalized these records to a peak ground acceleration of O.Sg <br />' and maximum ground velocity of 30 in/sec and determined the normalized displacements for various <br />ratios of resistance to earthquake acceleration. Newmark presented his results in a chart giving the <br />upper bound displacements calculated for each of the normalized strong motion records. <br />The Corps of Engineers (Franklin and Chang, 1977) has extended the data base for Newmazk's <br />' chart by processing many additional strong motion records and revised his upper bound limits for <br />displacement. A total of 169 horizontal and 10 vertical records from 27 earthquakes and 10 <br />synthetic accelerograms were used with the sliding block analyses. All strong motion records were <br />scaled to a maximum acceleration of O.Sg and maximum ground velocity of 30 9n/sec by adjusting <br />the acceleration and time scales. The results are presented in the form of a chart giving <br />standardized values of displacement which can then be utilized for any value of acceleration andlor <br />velocity through scaling factors. <br />Recognizing that an embankment dam does not behave as a rigid structure, Professor H. Bolton Seed <br />and his colleagues incorporated the dynamic response of the embankment into the displacement <br />' concepts originally proposed by Newmark. Makdisi and Seed (1977) utilized a furite element <br />program to determine the time-history of average accelerations in a variety of embartkntents and <br />' utilized the results of many other studies to evaluate embankment response. Ttley utilized these <br />results to determine the average acceleration acting on a sliding mass relative to the input ground <br />' July 13, 1993 9 SRK Project No. 14719 <br /> <br />