Abstract:

The tunnel of No. 4 Bid Section of Songhua River Water Diversion Project bored by TBM is about 17 km; and there are total 7 332 m crosses softweak and broken areas; i.e. limestone (karst), carbonaceous slate and fracture. The TBM often deviates, pitches and jammed when boring in the abovementioned areas. In this paper, the TBM construction cases, related expert consultations and construction schemes are analyzed and studied; and then a series of countermeasures for TBM continuous construction, i.e. advanced geological prediction and support scheme of steel arch frame + rebar row + shotcreting, are proposed. The practice shows that the abovementioned technologies are feasible and rational and can guarantee the TBM continuous construction in karst areas and softweak and broken grounds.

Key words: tunnel, karst, softweak and broken ground, open TBM, advanced geological prediction, rebar row support structure