Abstract:

The broken ground at exit section of Gaoligongshan Tunnel on DaliRuili Railway has adverse effect on TBM construction. Hence, a series of mehods for TBM releasing in broken ground, i.e. chemical grouting reinforcement ahead of tunnel face, small guide hole excavation and advance piperoof, are proposed; and TBM equipment improvements such as extending the shield and increasing the limit plate on scraper mouth are proposed as well. And then, for the problem that the surrounding rock is prone to collapse after shield passing, some countermeasures including strengthening the primary support and chemical grouting of tunnel top, installing template and pouring cement slurry at the waist of tunnel, and mechanized slag clearing at the bottom of tunnel, are put forward. The field practice shows that by adopting the abovementioned methods, the risk of TBM being jammed in the broken ground is reduced effectively, and the cutterhead releasing time is reduced, which improves the TBM boring efficiency in broken ground.

Key words: Gaoligongshan Tunnel, broken ground, fullface rock tunnel boring machine, cutterhead releasing, chemical grouting, guiding hole method, advance piperoof, equipment reformation