Numerical Analysis of Tunnel Design Effect of Excavation Damaged Zone on Principal Stresses and Total Displacement

The development of Excavation damaged zone (EDZ) in an underground opening can significantly affect the overall performance of the opening. Generally, it is believed that the presence of such zone in any kind of underground opening can pose big problem to seepage flow, stability and subsequently impair the general performance and functionality of the excavation. In order to assess the influence of EDZ on excavation, the behavior of the principal stresses and the total maximum displacement was observed in the present study. Therefore, this study is aimed at numerical design of underground tunnel and determining the effect of EDZ on the principal stresses (sigma 1 and sigma 3) and total maximum displacement surrounding the excavation. The principal stresses (sigma 1 and sigma 3) were observed to decrease with increasing EDZ thickness and corresponding increase in elastic modulus, while the shear stress was observed to increase. The total maximum displacement was also observed to decrease with increasing EDZ thickness and corresponding increase in permeability. The general conclusion drawn from the analysis is that mechanical properties principal stresses and (total maximum displacement) decrease with the development of EDZ around the tunnel.