Numerical modelling of vertical drains
DOI:
https://doi.org/10.24849/j.geot.2018.144.07Keywords:
Wick drains, stone columns, numerical modellingAbstract
The installation of vertical drains (stone columns and wick drains) in soft cohesive soils is a soil improvement technique frequently used for the foundation of embankments. Its application with preloading allows the acceleration of the consolidation of soil. This paper presents the numerical methods for modelling of vertical drains whose behaviour is of the tri-dimensional character. The evolution of settlements and dissipation of the excess of the pore water pressure during the consolidation is studied. To facilitate the two-dimensional analysis, it is necessary to transform the radial flow corresponding to the vertical drain in terms of a unit cell to the plane strain conditions. Additionally, in the case of stone columns, the equivalence of the deformability is required as well. For this reason, the conversion of certain geotechnical parameters is necessary to achieve the equivalence in consolidation grade and settlements in three-dimensional and two-dimensional models. This paper presents different existing methods of permeability transformation between the unit cell and the plane strain model that can be achieved by matching the permeability and/or geometry conditions. An example of the application is presented contrasting the obtained results of settlements and dissipation of excess pore water pressure during the consolidation. Finally, the failure mechanism of stone columns is studied in function of their position under the embankment load.
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