Numerical simulation analysis on stability of tunnel under unsymmetrical pressure during excavation

Based on an actual freeway tunnel project, this paper applied the finite element analysis software MIDAS/GTS and layer structure method to analyze the stability of tunnel under unsymmetrical pressure during excavation. The analysis results showed that in the process of excavating lateral drift, due to the unsymmetrical pressure the most disadvantageous locations of surrounding rock occurred at the two sides of arch crown and invert, and the largest deformation occurred at the position of crown settlement and foot, so the special consolidation measures should be taken. The safety effect on the primary support was greater when the temporary support was removed, so the removal length of temporary support should be controlled strictly during construction.