Abstract: Tunneling through water-rich fractured strata with double-shield tunnel boring machines (TBMs) presents considerable challenges to surrounding rock stability, leading to water inrush, mud gushing, and excessive settlement. Therefore, to address these challenges, a refined three-dimensional numerical model of the ground-TBM support system incorporating the surrounding rock, shield shell, segments, and synchronous grouting layer, is established and based on the seepage-stress coupling mechanism. This model systematically simulates the entire double-shield TBM tunneling, analyzing the dynamic coupling between the seepage and stress fields, and reveals the distribution of pore water pressure within the surrounding rock and evolution pattern of surface settlement. Subsequently, a collaborative control scheme is proposed and validated with field measurements. Our findings are summarized as follows: (1) A notable archshaped pore pressure disturbance zone, approximately 3 m of the tunnel axis, is observed along the excavation direction. The maximum pressure gradient occurs 2－3 rings behind the shield tail. (2) A hydraulic jump is identified at the stratigraphic interface, 11－12 m in the vertical direction, confirming water pressure accumulation due to differences in interlayer permeability coefficients. (3) Transverse ground settlement curves follow Peck distribution, with a 4.3 mm maximum settlement. (4) Based on the deformation characteristics of the surrounding rock, a collaborative control scheme including optimized grouting parameters, differentiated lining design, and specific TBM excavation parameter settings is proposed. Field measurements demonstrate that this scheme can control ground surface settlement within 4.3 mm, effectively mitigating largescale failure of the surrounding rock and enhancing rock stability.

Key words: double-shield tunnel boring machine, water-rich fractured stratum, fluid-solid coupling, pore pressure variation, surrounding rock deformation