Finite element simulations of twin shallow tunnels

Unlike for deep tunnels, prediction of displacements represents a key factor when analyzing tunnel excavation with low overburden, not only for defining the influence of the excavation on preexisting structures but also for providing a basis to put the observational method in place. The accurate assessment of the deformations induced by tunneling is strongly dependent on the choice of the appropriate constitutive model and on the parameter calibration against experimental data. The case study presented in this paper deals with the construction works of a new highway in Southern Italy, including five twin tube shallow tunnels. Considering that two-dimensional analyses are usually not able to reproduce simultaneously all the aspects of the stress-strain response due to tunneling, three-dimensional finite element analyses were performed in order to compare the results of the numerical analysis with the monitoring data. The available database includes a wide range of displacement and deformation measurements.