Contribution to the analysis of the bearing capacity of tunnels excavated in soil

The bearing capacity of foundations supported on soil depends on various factors such as shape of the foundation, depth of embedding, inclination of the load applied, base dimensions and type of soil. In excavations of tunnels, the camshaft support distributes stresses from the massif and from primary coatings directly to the soil. In these supports, a horizontal cut of the terrain is usual, and the base of the camshaft is kept at an angle by a pre-cast concrete element which is later filled with sprayed concrete. On the other hand, in some cases the projects are developed and analyzed numerically with a flat inclined support, which diverges from the common building practice. In this sense, the effects of terrain inclination in dimensioning and behavior of supports of tunnels excavated in soil are analyzed in this work by means of the proposal of Brinch Hansen and also via numerical modeling. The results showed that the inclination of the cut of the terrain influences the load capacity as well as the way stresses in the massif take place. Inclined supports allow stresses to be distributed externally to the tunnel section and, as a consequence, they have a greater load capacity. Therefore, it is critical for numerical analyses to be consistent with the building stages as they will be built. © 2017 University Federal de Uberlandia. All rights reserved.