Two Dimensional Simulation of Soil Moisture around a Leaking Water Pipe adjacent to a Concrete Slab

A method of predicting transient moisture distributions in soils beneath covered areas has been extended to examine the effects of a leaking water pipe adjacent to a concrete slab. The two dimensional unsaturated flow behaviour is predicted using solutions to the fully linearised Richards equation. Laplace and Fourier transforms are exploited to reduce the governing partial differential equation to an ordinary differential equation which can be solved analytically for a horizontal soil layer. Solutions for a layered soil profile are possible using a Finite Layer solution approach. The presence of a slab-on-ground is modelled by prescribing a zero flux segment at the upper boundary. Climatic effects such as rainfall and evaporation events are modelled using Type 3 boundary conditions, which regulate inflow and outflow as a linear function of the surface moisture content. The method of applying a Type 3 boundary condition in a transform solution formulation is described briefly. The presence of a leaking pipe adjacent to the edge of the slab is modelled by prescribing a source segment at a given depth. An example is provided.