Analysis of the behaviour of an old railway tunnel due to the construction of a Lisbon Metro tunnel

摘要

The Rossio railway tunnel, built in 1890 with a masonry lining, crosses several sandy and clayey strata, limestones and basalts. Recently, a new tunnel, part of the Lisbon Metro, was executed, crossing above the old tunnel at a short distance. In this paper, the geomechanical studies performed and the construction procedure are reported. The region around the tunnel intersection was analysed with a 3D numerical model, which allowed the simulation of the sequential excavation scheme, the reinforcement and support systems, and the non-linear behaviour of the geological strata. The results of a simplified seismic analysis, performed to evaluate the influence of an earthquake in both underground structures, are also presented.