Abstract
We made a study of some seepage characteristics in core zone of embankment dam, taking into account of anisotropy and heterogeneity of permeability simultaneously.Firstly, we reviewed some experimental studies on these characteristics that has been carried out and emphasized the necessity of analytical study.Secondly, we formulated two-dimensional finite element analysis of seepage through a core zone considering both effects simultaneously.Lastly, we demonstrated this numerical method selecting some typical shapes of core zone (inclined and central) and parameters ρ and γ which represented anisotropy and heterogeneity of permeability, respectively. And we discussed the effects of those factors on the potential distributions, exit points and discharge (Q).
The results are summarized as follows:
1) For both of inclined and central core type, the more remarkable the anisotropy is, the higher the phreatic surface and the exit point is.The other hand, the heterogeneity has not so influence on these locations, when ρ is constant. Concerning the potential distributions, however, the flow patterns considering the heterogeneity is much different from the cases considering anisotropy only and the equipotential lines are concentrated near the bottom of downstream face.
2) Relationship between discharge and anisotropy is recognized as linear in these simulations of both core types, when ρ is constant.And when the heterogeneity becomes remarkable, the discharge decreases.The rate of decrease shows larger for1<γ<5, but becomes smaller gradually as γ increases for 5<γ<50.
3) Using the normalized discharge by Q0 (discharge of isotropic core), relationships between Q/Q0 and ρ are linear for each γ value in both core types.Especially in case of central core, they are plotted on the same one line for all models.Getting the values of ρ and γ, discharge of anisotropic core studied here can be simply estimated by using the presented regression equations and tables.
