Esame del comportamento e della vulnerabilità sismica delle condotte interrate

After a brief description of the characteristics of pipes typically used for buried pipelines, the seismic behaviour of pipelines has been analysed on the basis of data collected during strong earthquakes in U.S.A. (California) and Japan. The most common damage modalities have been identified, highlighting that damage is mainly caused by the variability of soil properties and by the boundary conditions (tee joints, elbows, …) along the pipeline. The analyses show that the main parameters in determining seismic behaviour of buried pipelines are material, joint type, pipe diameter and soil characteristics. Also, damage data collected during and after the 1990 and 1991 earthquakes and relevant to the water delivery systems of four small towns near Potenza have been reported and analysed. Finally, based on the damage statistics and on empirical considerations, a procedure to evaluate the seismic vulnerability for buried pipelines is proposed.