Radial filtration model for prefabricated vertical drain treatment of slurry considering Poisson's effects

During the vacuum preloading treatment of slurry ground, the significant improvement is only observed in the soil adjacent to the prefabricated vertical drain (PVD), resulting in the formation of a protruding "soil column" with the PVD as its axis. The presence of soil column, as a unique phenomenon of slurry ground pre-treatment, leads to severe clogging and ineffective treatment results. An axisymmetric vacuum filtration model is established in the coordinate system using the continuity, kinematic and equilibrium equations for both liquid and solid phases of slurry. The moving boundary condition and Poisson's effects associated with the soil column are also incorporated. The growth pattern and clogging behavior of soil columns are investigated through the model and verified by comparing the predicted results with the particle image velocity (PIV) ones. The results show that reduction of permeability coefficient within the soil column is up to 97%, indicating that the dense soil column is the essence of clogging. Furthermore, notable influences of the Poisson's effects and negative pressure on the growth and compression behavior of the soil column are observed. The low amplitude negative pressure promotes formation of the relatively small loose soil columns, thereby mitigating the clogging behavior.