Grouting Parameter Effects on Structural Response: Precision Modeling of Soft Soil Tunnel‐Base Grouting via Cavity Expansion Theory and Mindlin Solution

Shield tunnels in soft clay are highly susceptible to long‐term uplift and differential settlement. To precisely control these deformations, this study develops a novel anisotropic cavity expansion model integrated with Mindlin's solution, forming a coupled 2D/3D segment–soil interaction framework. Validated against field data from Fuzhou Metro Line 4, the model demonstrates superior accuracy over traditional isotropic approaches. The results quantitatively reveal that: (1) in single‐ring grouting, increasing the grouting burial depth from 5 to 15 m reduces invert uplift by 28%; (2) in planar multi‐hole grouting, symmetric‐spacing sequences effectively control segment displacements within 5 mm; and (3) in longitudinal multi‐ring grouting, symmetric injection reduces maximum stress fluctuations by 12.5% compared to staggered grouting under a 5% grouting volume. The study concludes that the anisotropic soil–grout interaction is the primary mechanism governing deformation, and the proposed model provides a foundation for optimizing grouting parameters to ensure tunnel stability.