Discussion on key issues of TBM construction for long and deep tunnels

Aiming at high water-pressure, great ground stress, high ground temperature, large deformation, difficult supporting and other problems in the construction of deep and long tunnels, the superiority and disadvantage of tunnel construction method are conducted, such as drill-blasting method, TBM method, and TBM bored pilot+enlarging method. TBM bored pilot+enlarging method provides a new idea for tunnelling design of deep and long tunnels. Due to the remarkable differences in geological condition between deep tunnels and shallow tunnels, there are three crucial problems for TBM construction, namely, rockburst, TBM jamming (large deformation), and construction accidents (water gush, mud burst, etc.) attributed to inaccurate geological prediction. In order to detect the occurrence of TBM jamming, theoretical analysis and numerical simulation of TBM construction are conducted in deep soft rock and hard rock under certain geological conditions. The results show that the jamming occurs in deep soft rock, but never happens in intact hard rock.