ABSTRACT This paper presents a numerical study on cutterhead-soil interaction and its influence on tunnel face stability for stationary and rotating cutterheads. A parametric study was carried out for different friction angles, cover depths, and face pressure. The results indicate that the required face pressure is influenced significantly by the cutterhead-opening-soil interaction. As face pressure is progressively reduced from a high value, stability of the soil across an opening is initially maintained by arch action. The transfer of load from the opening to the springers of the arch leads to an increase in cutterhead thrust. This reaches a peak value after which the arch collapses. A higher friction angle of the soil allows the arch to remain arched at lower face pressure. Under torque-free condition, a higher cutterhead-soil interface friction coefficient enhances stability slightly by mobilizing friction resistance on the soil at the springers of the arch.