Numerical modelling strategy to accurately assess lining stresses in mechanized tunneling

The paper presents a 3-D numerical strategy developed to accurately simulate the soil-shield and the soil-grout-lining interaction processes associated with the gap closure in mechanized tunneling. The problem is particularly relevant for the structural design of pre-cast lining of very deep tunnels subjected to high stresses. The numerical model works in large strain mode and simulates the main features of the excavation and construction processes including face pressure, cutterhead overcut, shield conicity, annular tail void grouting and time-dependent hardening of the grout, installation of the lining inside the shield and jacks’ forces. The proposed approach overcomes in a very simple and effective manner the numerical inaccuracies associated to the erroneous shape of the excavation profile numerically obtained due to non-symmetric pre-convergences.