FINITE ELEMENT SEEPAGE FLOW MODEL FOR UNSATURATED LOESS WITH JOINTS

A finite element method is established for calculating the seepage flow in loess with consideration of its joints' influence. The basic seepage flow equation in unsaturated media is worked out with the view of conservation of mass. It is about the velocity and the saturation's expression. Appling the Darcy law, the variable can be changed from velocity to hydraulic head in the equation. The parameter in the basic flow equation of loess joints is determined according to the characteristic of loess vertical joints. Using the quadrilateral isoparametric element, the finite element form of the equation is given with the Galerkin weighted residual method. Under local Dirichlet boundary condition, the loess 2-D seepage problem is numerically studied considering the influence of loess joint. The results show that joint has a huge influence on the migration of wetting front.