Three-dimensionalnumericalmanifoldmethodforunconfinedseepageanalysisisproposedinthisarticle.Byconstructinghydraulicpotentialfunctionsofthemanifoldelement,theelementconductivitymatrixandtheglobalsimultaneousequationsforunconfinedseepageanalysisarederivedindetail.Thealgorithmoflocatingthefreesurfaceandtheformulaforseepageforcesarealsogiven.Three-dimensionalmanifoldmethodemploysthetetrahedralmathematicalmeshestocoverthewholematerialvolume.Intheiterativeprocessforlocatingthefreesurface,themanifoldmethodcanachieveanaccurateseepageanalysisofthesaturateddomainbelowthefreesurfacewithmathematicalmeshesunchanged.Sincetheshapeofmanifoldelementscanbearbitrary,thedisadvantageofchangingthepermeabilityoftransitionalelementscutbythefreesurfaceintheconventionalFiniteElementMethod(FEM)isremoved,andtheaccuracyoflocatingthefreesurfacecanbeensured.Furthermore,theseepageforceactingonthetransitionalelementscanbeaccuratelycalculatedbythesimplexintegration.Numericalresultsforatypicalexampledemonstratethevalidityoftheproposedmethod.
