L’individuazione di anomalie nel substrato di imposta della diga in terra sul torrente Astrone (Siena) e possibili cause del cedimento del rilevato

The dam on Astrone stream, where in 1970 occurred a minor instability located on the right bank, has been the object of our search in order that the reason of partial settlement of earthfill was found out. In 1997 and 2000 were execute geognostic analysis, topographic survey on earth complex, storage and surroundig structures. All fissuring meters fit in control room well, 5 soundings anchor to bedrock, laboratory test and monitoring with inclinometers and piezometers shown a slight settlement of embankment. In October 2004, a stability control of downstream side is carried out where more inclinometers, piezometers and estensimeters were installed within boreholes. Measurements are carried on all 2005 with execution of two refraction seismic profiles (P and S waves) that allows to characterize sill morphology. Geophysical survey underlined that, as previous investigations had defined, dam complex is homogeneous-type.