Amin Keshavarz

Earthquakes may directly affect the limit support pressure of the tunnel face through its stress redistribution on the soil surrounding the tunnel. Due to the lack of previous research on this topic, this study aimed at investigating the influence of seismic loading on the limit support pressure of shield tunnels. To achieve this, face stability of an undrained heterogenous clay, characterized by the Tresca failure criterion, was investigated by using the lower bound finite element limit analysis. The entire domain is simulated to be subjected to a range of pseudo-static horizontal earthquake body forces pointing out toward the heading. To facilitate the preliminary design process, the results have been presented in the form of dimensionless graphs including the horizontal seismic coefficient, influential factors and limit support pressure. Findings of analysis showed that an inclusion of the seismic coefficient will increase the size of the failure zones which subsequently affects the limit support pressure.