Laserfiche WebLink
<br />(10) Stabilizing slopes around the reservoir rim to prevent <br />slides into the reservoir. <br /> <br />(11) Providing special details for treating the enbankment- <br />foundstion interface if there is a potential for fault <br />movement in the foundation. <br /> <br />(12) Providing good quality, free draining rockfill shells. <br /> <br />(13) Remove foundation materials that may present potential <br />p rob 1ems . <br /> <br />Defensive measures should be the first consideration in <br />arriving at a solution to problems suggested by the possibility <br />of earthquake effects. Since the occurrence of liquefaction <br />and slope instability may invalidate the beneficial effects of <br />defensive measures, these two concerns warrant analytical <br />effort of sufficient sophistication to define their <br />possibility. <br /> <br />c. Methods of Analyses <br /> <br />(1 ) General <br /> <br />For a dam and foundation not subject to liquefaction, <br />deformation should not be a problem if all of the <br />following conditions are satisfied: <br /> <br />(a) The dam is a well-built (densely compacted) dam and <br />peak bedrock accelerations are 0.2g or less; <br /> <br />(b) The slopes of the dam are 3 horizontal to 1 vertical <br />or flatter (These slopes are applicable to <br />earthfill dams. Slopes could be steeper on rockfi11 <br />dams with central or inclined cores); <br /> <br />(c) The static factor of safety of the critical failure <br />surfaces involving the crest (other than the infinite <br />slope case and rapid drawdown) are greater than 1.5 <br />under loading conditions expected prior to an <br />earthquake; and <br /> <br />(d) The freeboard is 2 to 3 percent of the embankment <br />he igh to <br /> <br />If these conditions are not satisfied, a deformational <br />analysis should be made using the Newmark approach; or <br />alternatively, a deformational analysis using a finite <br />element-strain potential approach may be used. <br /> <br />(2) Liquefaction Analysis <br /> <br />The evaluation of the potential for liquefaction of silts, <br />sands, and gravels at a site requires specification of the <br /> <br />-24- <br />