Mathematical and numerical modeling of pore pressure dissipation and deformation of soft clay foundations stabilised with synthetic band drains and sand compaction piles

This paper describes an analytical model developed by the authors to quantify the smear effect and well resistance, and to investigate its role on soft clay behaviour. The mathematical model has been incorporated in a 2D plane strain finite element code employing the modified Cam-clay theory. In this technique, the vertical drain system is converted into equivalent parallel drain walls by adjusting the spacing of the drains and then transforming the coefficient of permeability of the soil to an equivalent plane strain value. The transformed permeability coefficient is incorporated in SAGE-CRISP through appropriate subroutines. The plane strain results are compared with the axisymmetric model results, and the numerical predictions are compared with the field measurements. The results conclude that mathematical models representing the effects of smear and well resistance are necessary for describing the true behaviour of PVD in soft clay, and that both the smear and well resistance should be minimised to improve the effectiveness of PVD in soft compressible soils.