Numerical Analysis to Determine Squeezing Potential of Deep Tunnel

Abstract

Squeezing refers to large, time-dependent deformations that happen around the tunnel perimeter. This phenomenon commonly occurs in tunnel excavations with poor rock mass class and very great depth. In many cases, squeezing exerts considerable pressure, which can damage the installed tunnel support system. In this study, numerical modeling was carried out on 10 tunnels in both squeezing and non-squeezing conditions based on data from the literature, using actual support pressure values to obtain modeled convergence values that match the observed ones. The results showed a difference between the numerical and actual convergence values that were due to additional pressure from squeezing. This squeezing pressure was then modeled by increasing the horizontal and vertical stresses until the numerical convergence matched the actual convergence. The effectiveness of this approach was confirmed by plastic zone validation in a selected case using the 2D FEM method. The final model successfully reflected real tunnel behavior, particularly in squeezing-prone zones. These results emphasize the importance of accurately modeling squeezing pressure to determine realistic deformation levels and develop appropriate support design.