Semi-analytical solutions to equal-strain consolidation of unsaturated composite ground with granular columns considering well resistance and smear effect

The composite ground is composed of middle-reinforced columns and the surrounding soils. For the permeable columns, they can not only withstand external loads but also form good channels for artificial vertical drainage and pore pressure reduction. Meanwhile, the air and water will flow through the vertical boundaries and radial granular columns. Therefore, the well resistance and smear effect cannot be ignored during the consolidation. This paper explored the influence of well resistance and smear effect on the consolidation of unsaturated composite ground with the equal strain hypothesis. Firstly, the polar governing equations are presented based on the flow rule of air and water phases under axisymmetric conditions and the basic relationships between the granular columns and surrounding soils of composite ground. Then, the Laplace transformation and Fourier sine series expansion are employed in the process of solving the governing equations to get the final solutions. By degenerating the solutions in this paper and comparing them with those in the existing literature, the correctness of the results is verified. Finally, the impacts of factors in terms of well resistance, smear effect, and columns on the consolidation behavior are investigated considering well resistance and smear effect, respectively.