Numerical modeling of shallow tunnels: analysis of the surface settlements

Resumo

The analysis of shallow tunnels is necessarily related to the study of the excavation influence on the

ground surface. As the excavation proceeds, surface settlements are expected to be generated, forming the so-
called settlement basin. Thereby, its correct evaluation is important since these movements could create

disturbances in surrounding structures. Estimation of tunneling-induced ground movements can be done by
analytical, empirical, and numerical methods and, currently, the best assessment of tunneling process consists of
finite element modeling. The current paper presents a numerical model elaborated in the software ANSYS with
the aim to evaluate the surface settlements induced by tunneling. The 3D finite element model concerns soil and
lining elements, using the activation and deactivation tool to simulate the excavation and lining placement. To
perform the analysis, the soil mass was represented by a plastic model using the Drucker Prager criterion and the
concrete lining is considered elastic. Five reported cases of real tunnels (Heathrow Express, Green Park, Barcelona
Subway, Brasília Subway, and São Paulo Paraíso tunnels) are simulated to validate the model with analytical and
experimental solutions.