Behaviour of segmental tunnel lining under static and dynamic loads

The aim of the research thesis is to provide a three-dimensional numerical model suitable to interpret the static and dynamic behaviour of a kind of segmental tunnel lining in soft soil. The static performance of the structure is investigated during the tunnel construction, involving the main tunnelling loads, obtaining the evolution of the state of stress and strain in the lining. The dynamic performance of segmental lining has been investigated both under uniform and not uniform seismic loads. In the case of uniform seismic load, pseudo static and full dynamic approaches have been compared, while non-linear coupled analysis have been used to investigate the post-earthquake lining condition. A study of the seismic vulnerability of such structures has been conducted based on fragility curves for different levels of damage. A procedure for the forecast method of risk assessment has been proposed for the case of segmental tunnel lining assuming as critical damage parameter the longitudinal joints rotation. Furthermore, a study of feasibility of Earthquake Early Warning System, EEWS, based on thresholds has been conducted through a probabilistic and a real-time approach for such tunnel structure. The coupling effect of multi-directional seismic motion both in transversal and longitudinal direction of the tunnel has also taken into account in the evaluation of dynamic tunnel behaviour. A comparison between the effect of synchronous and not synchronous seismic motion along the tunnel axis has been done in terms of dynamic increment of the components of forces in the lining.