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 byGPS and inclinometers ranged between mm and dm per month, with sliding depth varyingfrom 20 to 40 m. In this crucial sector of the landslide a mitigation option is the constructionof rows of wells coupled with pile-founded retaining structures. The effect of suchcountermeasures was estimated by finite difference method, using FLAC 2D programme.Elasto-visco-plastic behaviour along the sliding zone was simulated with Burger’s viscositymodel. Plasticity and viscosity parameters were determined in back analysis by fittingcomputed and measured displacements in fully saturated conditions. Numerical simulationshowed that lowering ground water level for several meters is not sufficient to significantlyreduce movement rate and that retaining structures introduced into the model do not achieve acomplete mitigation of movements, since parts of the slope far-off the structure keep moving.