Tunnel face stability in cohesion-frictional soils considering the soil arching effect by improved failure models

To better assess the stability of tunnel faces in cohesion-frictional soils, tunnel face stability was investigated considering the soil arching effect in this study. An improved 3D rotational failure model based on the limit analysis method and an improved wedge-prism model based on the limit equilibrium method were proposed. Simultaneously, the lateral stress ratio K-s was improved to reflect the soil arching effect. The support pressures obtained by the two proposed models were validated by the numerical results and existing works. Finally, the effects of the geometrical and geotechnical parameters and loading conditions on the tunnel face stability were assessed.