3D numerical modelling and settlement monitoring during excavation of the Metro-Torino South extension

摘要

The Metro-Torino South extension is under construction. The excavation of a 3.9 kmlong tunnel was recently completed by a 7.8 m diameter EPB Tunnel Boring Machine. A critical section ofthe line is represented by the underpass of Corso Spezia, in the Lingotto area, where the main difficultiesare associated with the high water table and the poor ground conditions encountered. Concern was alsoraised due to the influence of the excavation on two adjacent masonry buildings of 1930. This requiredan intensive monitoring system to be designed and installed. Monitoring took place continuously duringexcavation and allowed one to infer a time dependent function which describes the settlement history satisfactorily.A 3D finite element model was also created to simulate the excavation process and its effects onthe adjacent buildings. This model was validated through a back analysis procedure in order to assess thesoil parameters and simulate the tunnel excavation in stages. This paper will describe the case study andthe 3D numerical modelling work by comparing the results obtained with the monitoring data.