Tunnels in Tropical Soils—A Sensibility Analysis of Soil Parameters Applied on the Construction of Line 5 of the São Paulo Metro

Tunnels have become the preferred solution for the development of underground assets, especially in urban areas. Many cities are established in regions constituted by tropical soils which geotechnical behavior differs, to some extent, to that of temperate regions. This peculiarity of soil behavior affects the estimation of ground movement due to tunnel excavation. This paper presents a sensibility analysis using tornado diagrams to address the uncertainties of geotechnical properties for the assessment of tunneling-induced surface settlement. The analysis was conducted on part of the recent expansion of Line 5 of the São Paulo Metro. Two-dimensional (2D) finite element numerical analyses, based on the Mohr–Coulomb constitutive model, were carried out to reproduce the behavior of the tropical soils due to TBM tunneling. For that, data from a series of laboratory testing were used to characterize the stress–strain behavior of the residual soils. The evaluation of the variability of soil parameters was made by considering probabilistic scenarios based on the lower, mean and upper bound values of the coefficient of variation of input variables. The analysis allowed to identify which soil parameters have significant influence on ground movements considered for this case study. Finally, a comparison from the results of numerical analysis with the settlements measured from field instrumentation is presented showing a good agreement.