General Semianalytical Solution for Axisymmetric Consolidation of Unsaturated Soil with Unified Boundary under Electroosmotic and Surcharge Preloading

Abstract

This study proposed a general semianalytical solution for axisymmetric consolidation of unsaturated soil where the unified boundary is extended under electroosmotic and surcharge preloading, allowing for the diversity of permeability at the top boundary of the soil layer. In the coupled electric-flow-mechanic fields, the Laplace transform, decoupling technique, and Laplace inversion were used to derive a semianalytical solution. Then, the proposed solution was examined respectively against the two cases of considering only electroosmosis in saturated soils and only surcharge preloading in unsaturated soils to verify the validity of the solution. The analysis of the factors affecting the consolidation characteristics shows that as the permeability of the top boundary increases, the excess pore pressures dissipate faster, and then the final negative excess pore-water pressure decreases. The electroosmotic-enhanced preloading technique can significantly improve the speed of foundation consolidation and reduce the post-work settlement compared to a single method. Moreover, the excess pore pressures induced by the surcharge preloading dissipate faster as the electrical-to-radial water permeability ratio decreases. It is meritorious to note that the new solution in the present study is applicable to the axisymmetric consolidation model for unsaturated soils under arbitrary time-varying loading and different permeability topsides.