THE NUMERICAL SIMULATION OF PIPING IN THE TWO-DIMENSIONAL EMBANKMENT

Based on the modified SPV (Stavropoulou-Papanastasiou-Vardoulakis) control equation, the seepage erosion of a two-dimensional homogenous embankment dam with free surfaces is numerically analyzed by employing the Newton-Raphson method and conducting matrix adjustment finite elemental method. The numerical analysis shows that the hydraulic gradients around both the overflow surface and the free surface are bigger than those in other regions, so they more easily exceed the critical hydraulic gradient for piping in a homogenous dam with free surface seepage. The erosion area (Porosity increases significantly) and the area of maximum fine particle concentration first occur near the spilling area, then extend to upstream along the seepage free surface, finally reaching the water inlet near the free surface and forming a channel. Piping erosion enhances the coefficient of permeability and has significant effects on the seepage velocity, though it has little effect on pore-pressure distribution and free surface location.