Author(s): Corrado Gisonni–Roberto Greco; Rudy Gargano
Linked Author(s):
Keywords: Urban hydrology; Sewer failure; Unsaturated pyroclastic soil; Reliability index
Abstract: In 1997 the city of Naples was heavily hit by tragic event due to sewer failure and consequent formation of large cavities below the road level. The failure mechanism is strongly depending on particular soils involved. In this paper the phenomenon is highlighted, with respect to leakage from sewer networks subject to pressurised flow. A simple procedure is proposed, in order to estimate the risk correlated to pressurised flow in sewer channels buried in unsaturated pyroclastic soils. The procedure defines a critical event with respect to the risk of excavations over channel top, by studying the time dependent flow in unsaturated soil caused by leaching from pressurised sewer channel. A dimensionless abacus is derived, allowing to identify critical events for general situations. Some criteria to evaluate the reliability of an existing sewer network are presented, with special respect to the probability of a structural collapse of the channel together with the surrounding soils. Finally, an application of the procedure to a channel of Naples sewer network is presented.
Year: 2001