Objectives While passing through a deeply buried water-rich fault fracture zone, a tunnel boring machine (TBM) frequently faces an extremely high risk of water inrushes, seriously restricting the engineering safety and efficiency.

Methods  This study aims to reveal the evolution patterns of water inrush disasters in the case where the TBM roadway tunneling passes through faults zones and propose technologies for advance prevention and control to mitigate the water inrush risk. Against the engineering background of the tunneling of a main roadway in a coal mine within a North China-type coalfield, this study established a 3D numerical model using the FLAC^3D software to stimulate the TBM tunneling passing through a deeply buried fault fracture zone while considering the stress-damage-seepage coupling effect of surrounding rocks. Then, using the model, this study conducted simulation analyses of the spatiotemporal evolution characteristics and patterns of the displacement, plastic zone, permeability coefficient, and water inflow of surrounding rocks as the TBM approached the deeply buried fault. Based on the mechanisms behind water inrushes, a comprehensive reinforcement scheme centered on advance segmented grouting was proposed.

Results and Conclusions As the TBM approached the fault, the surrounding rocks behind the tunneling face showed a significant three-stage spatial differentiation in displacement and plastic zone range. In contrast, the surrounding rocks in front of the tunneling face exhibited an exponential increase in displacement and plastic zone range and a surge of approximately 106 times in the permeability coefficient due to intensified damage. As a result, a continuous water-conducting fracture network was formed, ultimately inducing the overall instability and water inrush disasters of the surrounding rocks. The surrounding rocks presented an exponential increase in water inflow with an increase in hydraulic gradient under TBM roadway tunneling. Notably, at the critical water inrush distance (i.e., the distance between the tunneling face and the fault) of 3.0 m, the instantaneous water inflow reached up to 956.1 m³/h. After the reinforcement scheme of surface directional drilling combined with advance segmented grouting was implemented for the surrounding rocks within the influence range of the deeply buried fault fracture zone, the displacement, water inflow, and permeability coefficient of the surrounding rocks were effectively controlled, ensuring the tunneling safety. The results of this study provide a basis for the scientific decision-making regarding the TBM tunneling safety. Furthermore, these results hold significant engineering value for enhancing the environmental adaptability of TBM equipment under complex hydrogeological conditions and for improving the dynamic early warning system and the prevention and control technologies for water inrush mitigation.