Comparison of Two Main Techniques in Staged Tunneling Using Numerical Simulations and Design Charts

Tunneling techniques with their own advantages and disadvantages have been applied all around the world depending on site conditions and economy of the task. In the present work, 2D numerical simulations of an arch shaped tunnel considering two traditional techniques (Cut and Cover and NATM)have been presented. The study focused upon the stresses induced in the lining due to the two different construction procedures and the results were obtained in terms of the moments and displacements borne by the structural system. Imposed loadings in the two techniques are assessed and finally engineeringjudgment on the overall performance of the tunnel is discussed. The comparison shows that moreemphasis should be put on strength properties of tunnels made via NATM. Less axial forces in conjunction with more bending moments for NATM tunnels are another observation made in the current study which highlights prominent effect of moments in NATM procedure.

Keywords:

Tunneling , NATM , Cut and Cover , Numerical simulation , Bending moment