Abstract: A tunnelling machine for large cross-section tunnels (with a 12 m diameter and more), as well as for excavating loose rocks leading to groundwater, has a shield with a cylindrical case. A front section (1) of the case is rotary. The front face (3) of the rotary section is designed at least outside a central area (11) as a helical heading supporting surface at least approximately full when seen in the axial direction (6) of the tunnel. Preferably, the supporting surface is composed of several helical surfaces (4, 5) that supplement each other in the circumferential and/or radial directions. In the supporting surface is arranged at least one excavating shoulder (12, 13) whose surface is at an angle with respect to the supporting surface. An excavating device is preferably arranged on at least one excavating shoulder (12, 13). In the area of the supporting surface the earth or rocks are supported at the same time as they are excavated exclusively at the excavating shoulder(s).