ABSTRACT

Small-scale changes of different rock types with different mechanical properties or of different degrees of fracturing are typical especially in sedimentary and metamorphic rock masses. In TBM tunneling, these conditions may pose mixed face conditions with different excavability at the same face. Particularly with large diameter TBMs, these conditions affect the speed of advance and the tool wear. This paper discusses cases from actual projects, offers a new definition for Mixed Face Conditions and suggest their risk management.