In order to improve engineering properties of soft deposit, the preloading method combined with drainage systems is the most popular and efficient scheme. In that case, it is necessary to take into account for the three-dimensional effect of drainage systems on the behavior of soft deposit. However, it is not effective to simulate the real three-dimensional field behavior in the numerical analysis. Thus, an equivalent two-dimensional model is developed in this study on the basis of the finite element technique.
The main concern related with the construction method is the time-dependent behavior of soft deposit due to the preloading. Several methods have been proposed to effectively model the three-dimensional behavior by comparing the amount of flowing water or the amount of settlement at any time, respectively. It has been found, however, that the proposed methods may not represent the whole range of real three-dimensional time-dependent behavior.
In this study, a simultaneous consideration of the amount of flowing water and the settlement at any time has been taken and an equivalent permeability($k_{eq}$) has been derived. The stiffness of drainage system was also adjusted in the two-dimensional equivalent model. The results were compared with those obtained from the three-dimensional analysis. It has been validated that the proposed model well approximates the whole range of real three-dimensional time-dependent behavior in considering the real well resistance effect.
