ABSTRACT
This study describes the effect of smear zone and well resistance in a vertical drain analysis using a 2D plane strain finite element model employing a modified Cam-clay theory. The vertical drain system was converted into equivalent parallel drain walls by adjusting the spacing of the drains and the coefficient of permeability of the soil and then incorporated in CRISP through appropriate subroutines. Determination of the extent of smear zone around the vertical drain using a large-scale consolidometer is also described. The results reveal that the extent of smear zone can be established as a function of the ratio of horizontal to vertical permeability. The analysis of a selected case histories using the authors’ model conclude that the accuracy of the predictions can be improved by incorporating the smear zone and well resistance in the model for both prefabricated vertical drains and sand drains. The effectiveness of vacuum preloading in conjunction with the vertical drains is also discussed based on experimental results.
