Details:
The SP n. 164 provincial road was damaged by a complex composite landslide activated in loc. Bagnaschino in the Municipality of Torre Mondovì during the flood events of November '94. In order to continuously monitor the stability conditions of the slope, in 2008 the Province of Cuneo started the deep monitoring with the installation of a DMS Slope column in the borehole of a 60 m long.
In the period 2008-2009, 5 reactivations, closely related to intense meteoric events or snow melting, were investigated along the most superficial sliding surface at 7 m bgl. The DMS column has allowed to continuously obtain the kinematics of the aforementioned events, not only limited to the initial stages but also to the reactivation and evolution of the phenomenon until the new stasis conditions are reached.
Through the analysis of the reactivation events recorded, it was possible to identify the specific site model of the landslide with calculation of the curve of intensity/duration of the precipitation events able to reactivate the failure.
This model has allowed the prior implementation of measures to protect public safety following weather warnings, such as the closure of the SP 164 during the meteorological event of March 2011. Specifically, starting from 12.03.2011 the DMS column registered micro-displacements that have grown until reaching, on 17.03.2011, a cumulative shift of over 60 mm. The provincial road was closed to traffic on 13.03.2011 after the first deformations and the forecast of the meteorological bulletin; the reopening was ordered on 21.03.2011 following the registration of the deformation arrest.
The DMS column, in spite of the sensible movements of the landslide with a displacement of over 600 mm on a single module, worked properly during the monitoring period and was recently extracted from ARPA Piemonte as part of an agreement with the Province of Cuneo to be used in other sites of the province.
The case history of the Bagnaschino landslide, from Early Warning to site specific rainfall threshold. - The Second World Landslide Forum, Roma 2011