Consolidation of unsaturated composite ground reinforced by permeable columns

In this paper, the governing equations and semi-analytical solutions are proposed to investigate the consolidation behavior of unsaturated composite ground with the permeable columns. Based on the stress and strain equilibrium conditions of composite ground and the strain–stress relations of unsaturated soils under the axisymmetric condition, a set of the basic equations are proposed for describing the strain–stress relations of soil element, air and water phases of unsaturated soils in the composite ground. Then, two consolidation equations for air and water phases are derived considering the continuity of pore volume change, and flow laws for air and water phases under the axisymmetric condition. Correspondingly, the semi-analytical solutions of the consolidation equations are proposed by using the Laplace and finite Hankel transforms. The proposed governing equations as well as the semi-analytical solutions are verified by checking against the existing ones for a special case in the literature. Finally, a parametric study is performed to investigate the consolidation behavior with different parameters for the permeable columns and surrounding unsaturated soils.