NUMERICAL-ANALYSIS OF SEDIMENTATION AND CONSOLIDATION BY THE MOVING FINITE-ELEMENT METHOD

Traditionally, sedimentation and self-weight consolidation have been viewed as physically distinct processes requiring separate treatment. Relatively recently, Pane and Schiffman(1) and also Philip and Smiles(2) have suggested that the two processes may be described by a single partial differential equation, essentially that of Gibson et al.(3) The former suggests a modification of Terzaghi's effective stress principle while the paper by Philip and Smiles suggests that a suitable modelling of material properties is sufficient. We have adopted the latter approach by allowing for the compressibility of the material in question to change abruptly from finite values to infinity in the so-called transition region which delineates that portion of space where effective stress is zero from that where effective stress in non-zero. This procedure gives rise to serious difficulties when trying to solve the governing partial differential equation numerically. These difficulties are circumvented by using a relatively new numerical technique known as the Moving Finite Element (MFE) method. The MFE method is especially effective in solving problems having solutions that characteristically exhibit shock-like structure. The modelling of sedimentation and self-weight consolidation from a single governing model is an ideal candidate for MFE due to the abrupt, almost discontinuous change in void ratio displayed in the transition region.