The paper describes the three-dimensional numerical model of Ville San Pietro, an Italian village subject to slope movements causing damage. The church (dating back to 1776), which is the most significant building of the area, is modelled too. The information from geotechnical and geophysical surveys on field are used to define the model geometry and the soil properties. A finite element code is adopted to simulate the slope behavior in occurrence of water table fluctuations, detected by piezometers, and to evaluate the slope displacements and stability. The validation of the model is carried out using the inclinometer and interferometry measures and by on-site inspections. The model demonstrated a good ability to simulate the slope behavior during the raising and lowering of the water table. The critical areas computed by the numerical code are in good accordance to the actual portions affected by soil displacements and damages. The modelling presented in this paper is crucial for future analyses that will take advantage of an innovative monitoring system, which will be installed on site.

This paper describes a simple methodology to calculate the two-dimensional seepage across an infinite unsaturated slope using models of one-dimensional infiltration through horizontal ground. The methodology decomposes the seepage across the infinite slope into antisymmetric and symmetric parts, whose respective solutions are combined to calculate the actual flow regime. The antisymmetric solution is trivial and does not even require integration of the governing continuity equation while the symmetric solution, albeit non-trivial, reduces to the case of one-dimensional flow through horizontal ground, for which solutions already exist. The methodology is generally applicable to the calculation of distinct seepage regimes across unsaturated slopes with different hydraulic properties under both stationary and transient conditions. The paper also defines the gradient of the piezometric head parallel to the slope, which is the Neumann boundary condition to be imposed on slope sections perpendicular to the ground surface. The rigorous definition of this gradient overcomes the need of imposing arbitrary boundary conditions in finite element models. Finally, the paper demonstrates that all infiltrated water crosses the slope along the shortest path, i.e. the path normal to the surface, while the flow parallel to the slope is entirely fed by an upstream source at infinite distance.