Settlements control in driving a shallow tunnel

摘要

This paper will introduce an experience of tunnelling through a difficult ground, under low overburden and in the presence of some buildings located less than ten meters above the tunnel crown. The tunnel portion is in very weak clayey marl and marly clay. A clayey and sandy weathered surface affected the crown increasingly as the overburden decreased. The design provided a full section excavation with the RPUM. In this case RPUM (reinforced protective umbrella method) is a steel pipe roof protection of the opening boundary, a fiberglass tube face consolidation, a first phase lining consisting of shot concrete and steel ribs, invert casting close to the face and crown lining completion at the least possible distance from the face.