The earthquake of 26 September 1997, one ofthe largest seismic events of the last 20 years in Italy, caused significant damage in a large area of Umbria and Marche regions. The national strong motion network recorded very high peak ground accelerations (PGA), whose maximum value was of about 0.56 gat the town of Nocera Umbra, and significant local soil amplifications. The Acciano zoned earth dam, sited close to Nocera Umbra, suffered damage to the crest structure, consisting mainly in longitudinal cracks, maximum settlement of about 20 centimetersand lateral displacement of l0 centimeters in the downstream-upstream direction. The behaviour of the dam during the main shocks is examined in the paper by using the Newmark’s method of analysis and a comparison is made between computed and observed dam deformations. Moreover an attempt is made to correlate the conventional factors of safety deriving from pseudo—static approach with allowable deformations. The lessons learned from the “real scale experiment made by Nature” consist in the confirmation of the usefulness of the Newmark’s method in the assessment of the behaviour of earth dam during strong earthquakes and that the minimum factors of safety prescribed by italian code granted the dams to withstand PGA up to SA times the constant level of acceleration introduced in the pseudo-static approach.
The earthquake o …
AUTORI: Paoliani P. RIG ANNO: 2000 NUMERO: 2 Numero di pagina: 20