ABSTRACT
In the geotechnical engineering field both analytical and numerical solutions are used to estimate flow rates and pore water pressures associated with seepage in the presence of phreatic surfaces. Calculation of steady state flow rates and drawdowns for both confined and unconfined problems is often based on the assumption of predominantly horizontal flow (Dupuit’s assumptions). Under these assumptions, transient seepage can also be modelled as a sequence of steady states. When applied to transient flow, the Dupuit-Forchheimer assumptions, can lead to the one-dimensional, transient Boussinesq equation, which can be linearised. Thus, a number of analytical solutions can be obtained. For the majority of problems, however, use of numerical techniques such as finite differences or finite elements will be required. Two distinct approaches to modelling unconfined flow have been used with numerical models. Both approaches involve strong non-linearities, making their numerical solution challenging.
