Large-Strain Radial Consolidation Analysis Incorporating Soil Smear and Well Resistance Effect

Abstract

A mathematical model was developed to investigate the consolidation behavior of soft soil deposits improved by prefabricated vertical drains. The smear effect caused by drain installation was incorporated into the model by assuming a parabolic variation of permeability and compressibility with radius. The non-Darcian flow of pore water in the soil and the well resistance effect caused by the limited discharge capacity of drain were also incorporated in the model. The void ratio dependence of permeability and compressibility was taken into consideration to account for their variation with time. The proposed model was validated by comparing the predicted results with experimental data and with existing analytical models. A parametric study was performed to evaluate the influence of various parameters such as non-Darcian flow, permeability ratio, and discharge capacity on the consolidation of the soil deposit. The average effective stress decreased by approximately 20% when the ratio of permeability in the undisturbed zone to the smear zone was increased from 1.5 to 5. The average excess pore-water pressure at the soil–drain interface reduced by approximately 80% when the discharge capacity was increased from 20 to 100 m3/year. The well resistance effect was more significant for non-Darcian flow as compared to Darcian flow. The rate of dissipation of average excess pore-water pressure increased by approximately 75% when the non-Darcian parameter n was increased from 1 to 2. However, the average excess pore-water pressure became independent of the non-Darcian parameter (n) for n greater than 2.5.