Design, construction and behavior of deep shafts, for the reception and launching of a tunnel boring machine
This paper will present the design, construction and preliminary behavior of two cylindrical shafts, with an internal finished diameter of 12 m and approximately 118 and 78 m in depth, with structural preparations at its bottom for the reception and launching of a tunnel boring machine. The design was done with the aid of a numerical simulation by FEM, to represent the construction procedure of the excavation, by controlled stages, including the reinforcement of the walls. The shafts were instrumented with inclinometers, to compare with the results by the FEM analysis. During the construction procedure there was an interaction with the ground water. At the maximum depth, it was realized a circular demolition of the wall (8.9 m in diameter), to receive and launch a TBM. There was no need for soil improvement to do so, as it was identified in the analytical simplified analysis.