Theoretical and experimental study on the consolidation of soil with continuous drainage boundary under electroosmosis–surcharge preloading

Electroosmosis and surcharge preloading represent two effective soil consolidation methodologies. Their combined application has been proven to be effective in shortening the consolidation period and mitigating the degradation of electroosmotic consolidation performance due to crack generation. In this study, an axisymmetric free-strain consolidation analytical model incorporating a continuous drainage top boundary was established. A semi-analytical solution was then derived utilizing Laplace-Hankel transform and boundary condition homogenization. The validity of the proposed solution was confirmed by comparing it with three cases documented in the existing literature. Additionally, a comparison with indoor model box test results demonstrated the rationality of setting the top boundary as a continuous drainage boundary. Parameter analysis revealed several key insights: firstly, under the free strain assumption, the spatiotemporal distribution of excess pore water pressure aptly captured the coupled effects of the radial electric field. Secondly, the combination of electro-osmosis and preloading technology significantly improved consolidation efficiency, with this effect becoming more pronounced as the applied voltage increased. Lastly, the general solution based on the continuous drainage boundary proved to be suitable for addressing the consolidation of soft soils enhanced by vertical drainage, applicable to real foundation consolidation problems with top boundaries exhibiting different permeabilities.