A fully coupled finite element analysis of water-table fluctuation and land deformation in partially saturated soils due to surface loading

A fully coupled numerical model is presented for the water-table fluctuation and land deformation in partially saturated soils due to surface loading. This numerical model is developed based on the poroelastic governing equations for groundwater flow in deforming variably saturated porous media and the Galerkin finite element method. The numerical model is verified and validated against a one-dimensional consolidation problem concerning surface loading on a soil column which has six different initial water-table elevations. The numerical model is then applied to a two-dimensional consolidation problem of surface loading on a partially saturated soil at a construction site. Results from the numerical simulations of both problems show that the water table fluctuates in the partially saturated soils, and the unsaturated zone above the water table has significant effects on the consolidation behaviour of the partially saturated soils under surface loading. Such effects are caused by the permanent absorption of a portion of the mechanical loading stress and the weak hydromechanical coupling between the solid skeleton deformation field and the groundwater flow field in the unsaturated zone due to its partial saturation. Copyright (C) 2000 John Wiley & Sons, Ltd.