Incorporating Hydromechanical Coupling of Unsaturated Soils into the Analysis of Rainwater-Induced Groundwater Ponding

Abstract

The moisture contents and coefficients of permeability of partially saturated soils are assumed to follow an exponential function of the pressure head. A partial differential equation is proposed here to describe the groundwater flow in a partially saturated and deformable soil mass based on Darcy’s law, conservation of mass law, and elasticity theory. An accurate solution to the one-dimensional (1D) seepage equation was obtained using the Fourier integral transform. This solution was then applied to examine 1D infiltration into deformable soil that caused the groundwater table to rise. The model developed here can be applied to a 1D seepage problem in deformable soil with recharge at the surface and no flux at the base. As rainwater accumulates up from the lower boundary, the coupling effect increases. The thinner the soil layer, the faster the pressure-head profile builds up in coupled conditions (F < , swelling soils). The rise of the groundwater table is closely correlated to the coupling effect and is also affected by the soil properties, rainfall intensity, and depth of the soil layer.