The existing tunnel boring machines (TBM) construct tunnel surrounding rock is mainly for hard rock, and the open-type TBM construction of water-rich soft rock tunnel is an engineering problem.In view of the difficult geological conditions of water-rich soft rock in a mine project, the feasibility of open-type TBM construction in typical water-rich broken soft rock strata was analyzed from the aspects of geological condition adaptability, advancement by supporting shoes in soft and broken sandstone, and water-induced softening of water-rich broken sandstone using numerical simulation and field construction monitoring data. Graded support measures were put forward. The field monitoring results show that after using an open-type TBM for excavation and graded support, the maximum deformation of the roof is reduced from 9.2 cm to 4.5 cm, and the deformation degree is reduced by 51.5%, which effectively ensures the safety and stability of the surrounding rock of the roadway. At the same time, based on the field investigation, the construction cost and construction period were compared and analyzed, which further verified the feasibility of using open-type TBM construction. The final construction results show that the project takes 396 days to safely and successfully complete the excavation task. The maximum daily excavation is 31.53 m, and the maximum monthly excavation is 521.53 m. The excavation task is completed 6 months ahead of the planned construction period, which has good economic and social benefits.

Water-rich soft rock  /  Gently-inclined and long inclined shaft  /  Open-type TBM  /  Graded support  /  Numerical simulation