Three Dimensional Analysis of Seepage Through Fill Dam for Irrigation Using the Isoparametric Finite Elements

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With regard to planning design and construction of fill dam, Seepage within the dam body or through the foundation are one of important problems. Because of economical and safe performance of fill dams, it is needful to compute quantities of seepage flow in fill dams and their foundations.The results of this research are as follows.1 Steady state flow was dealt with in this seepage problem.2 In this case, a saturated-unsaturated finite element approach, as proposed by Nenman (1973), could be applied. The Newton-Raphson iteration algohithm is also used to obtain an approximate phreatic surface, because the pressure must be zero on the phreatic surface as this is exposed to atmosphere.3 With the shape of the three-dimensional isoparametric element, the variation of the unknown, phi, had been specified.4 The governing equation was written by the balance for steady-state flow and the finite element discretization was proceeded on the assumption of a trial function expansion, using either the week formulation of the governing equation or the variational statement of the functional giving on minimization the satisfaction of the original problem.5 A computer program to carry out a large set of simultaneous, linear algebraic equation solved by Gauss elimination was coded with FORTRAN programming language.6 In the paper, permeability identification procedure was based upon an output error criterion where an existing estimate of the coefficient of permeability was iteratively improved until the calculated phreatic surface was sufficiently close to that of the measured output.