Liquefaction Assessment of Zefta Barrage in Egypt

The Zefta Barrage is a vital hydraulic structure situated on the Damietta branch of the Nile River. This research mainly aims to evaluate the liquefaction potential under the Zefta Barrage and the associated damage. A range of field and laboratory tests are used to estimate soil parameters in order to construct a two-dimensional finite element model. The probabilistic seismic hazard approach (PSHA) is used to estimate the ground-motion parameters of the operating basis earthquake (OBE) and the maximum design earthquake (MDE) at the Zefta Barrage site considering local site conditions. The obtained response spectra are implemented in the spectral matching methodology to acquire reasonable time histories. The current analysis reveals that the structure is stable against liquefaction for the OBE, but the concrete blocks downstream need an extension to keep the structure a way off the liquefiable zone. On the other hand, for MDE, the downstream part of the structure is affected by liquefaction at the end of the downstream raft. This liquefaction is caused by a layer of liquefied sand occurring at a depth equal to 0.33 m. It is found that the barrage downstream needs limited strengthening to overcome the liquefaction effects.