Numerical investigation of the behaviour of hydraulically dredged fine-grained soils during and after filling of the containment facility of the port of Gaeta

Abstract

Fine-grained dredged sediments can be efficiently and sustainably handled by hydraulically filling containment facilities, which can then be reclaimed. This study presents two numerical modelling strategies, characterized by markedly different levels of complexity, that simulate the gradual filling and subsequent consolidation process. Both numerical models employ hydro-mechanical constitutive relations apt to cover wide state ranges, starting from very low effective stresses. Class A predictions of a well-documented case study, where an articulated construction sequence was implemented, are reported and the effectiveness of the two proposed strategies is compared. After updating the numerical predictions according to the recorded construction timeline, the numerical results are validated against field data, specifically versus the monitored height of dredged mud. Finally, the monitoring data are back-analysed, emphasizing the influence of the hydro-mechanical behaviour at high void ratios. The results show that both modelling strategies are sufficiently accurate and can provide substantial benefits to the design of the filling works and to the evaluation of the actual storage capacity of the impoundments, especially if the available volume is limited or if complex construction procedures are implemented.