Numerical analysis of the effectiveness of countermeasure works on earth slide stabilization: a case study in South Tyrol (Italy)

An active complex earth slide causes risk for the resort of Corvara in Badia (South Tyrol, Italy). Displacement rates measured in the source area from 2001 to 2004 by GPS and inclinometers ranged between mm and dm per month, with sliding depth varying from 20 to 40 m. In this crucial sector of the landslide a mitigation option is the construction of rows of wells coupled with pile-founded retaining structures. The effect of such countermeasures was estimated by finite difference method, using FLAC 2D programme. Elasto-visco-plastic behaviour along the sliding zone was simulated with Burger’s viscosity model. Plasticity and viscosity parameters were determined in back analysis by fitting computed and measured displacements in fully saturated conditions. Numerical simulation showed that lowering ground water level for several meters is not sufficient to significantly reduce movement rate and that retaining structures introduced into the model do not achieve a complete mitigation of movements, since parts of the slope far-off the structure keep moving.