Abstract: The consolidation characteristics of dredged slurry improved by vacuum preloading significantly deviate from conventional patterns due to its unique properties. However, there is a lack of large strain consolidation models that consider the development of soil columns during vacuum preloading, especially regarding the variation of soil clogging characteristics over time and spatial distribution. To address this issue, this study developed a large strain consolidation model for slurries improved by the vacuum preloading, incorporating the increasing radius of soil columns. The model integrates factors such as the variation of permeability with radius, time-dependent discharge capacity, soil self-weight, nonlinear compressibility and nonlinear permeability. The governing equations using void ratio as the control variable, were solved by the finite difference method to calculate consolidation behavior considering soil column variations. The proposed model was validated by comparing its predicted results with those from an existing analytical model. Based on this, a parametric study analyzed the influences of radial permeability distribution, soil column formation time and drain discharge capacity. The results indicate the necessity of considering soil column radius variation over time and its permeability relative to the distance from the prefabricated vertical drain in the computational model due to their significant influence. Ignoring the soil column development process underestimates both consolidation speed and degree, with errors exceeding 10%. Assuming the soil column’s permeability coefficient remains constant at different position along the radius also underestimates consolidation speed and degree, with the errors increasing as permeability decreases. The consolidation differences under various soil column radius growth times are substantial and increase as the soil column radius increases and the permeability coefficient decreases.

Key words: vacuum preloading, dredged slurries, large strain consolidation, soil column