Adjustment of Phreatic Line in Seepage Analysis by Finite Element Method

Department also publishes a continuing series of Bulletins. Lists of recently published titles in both of these series are provided inside the back cover of this report. Requests for copies of any of these documents should be addressed to the Departmental Secretary. The interpretations and opinions expressed herein are solely those of the author(s). Considerable care has been taken to ensure the accuracy of the material presented. Nevertheless, responsibility for the use of this material rests with the user. 1979 Synopsis In the appliaation of finite element methods to analysis of seepage through earth dams, previous researahers have reported various methods for adjust­ ing the phreatia line with differing degrees of sua­ aess in satisfying the exit boundary aonditions. This paper reviews five suah methods for phreatia line adjustment, and reports the results of a set of aomparison tests for assessing their relat­ ive performanae in terms of (a) position of the phreatia line, (b) pore pressures, and (a) estim­ ation of seepage flow rates. It is aonaluded that the method used for the adjustment of the phreatia line makes no signifiaant differenae to the results obtained in prinaipal appliaations and the ahoiae of method depends, there­ fore, on its suitability for the partiaular applia­ ation and the ease with whiah it aan be implemented.