ABSTRACT
After decades of tunnelling scarcity, Romania has restarted its major infrastructure projects, resulting in a significant increase in tunnel design and construction. One of the challenges in designing the conventional tunnels for Motorway A8 Targu Neamt-Iasi-Ungheni is the determination of the deconfinement effect of in-situ stresses due to tunnel excavation and support sequencing. A 3-step approach is analysed, using the analytical Convergence-Confinement Method (Marc Panet), a 2D Axisymmetrical Finite Element Model, and a 3D Finite Element Model. The first two methods simulate the 3D effects generated by the construction sequence in a 2D model, whilst the third method models the tunnelling steps in 3D. This paper aims to compare the three methods, outline the difference in results, and calibrate the 3D effects in the 2D model, thus adding more clarity to the ground deconfinement determination process for conventional tunnels in soft ground conditions.
