<p>Shield tunneling in close proximity to underground structure is recognized as a high-risk engineering challenge, especially in complex geological conditions. Implementing effective reinforcement solutions and selecting reasonable tunneling parameters are key to controlling structural deformation and surface settlement. This study focuses on a double-line shield tunnel for Chongqing Metro Line 15, which passes beneath an underground pedestrian tunnel. Jet grouting was applied in different sections of the strata, and various shield tunneling parameters were selected for construction. By monitoring surface and ground structure settlement values, the rationality of tunneling parameters was assessed. The study established correlations among shield tunneling parameters and demonstrated the influence of different parameters on settlement patterns. The results indicated that shield speed and cutterhead torque had an insignificant positive linear correlation, while the relationship between thrust pressure and total tunneling thrust followed a quadratic function. The first shield tunnel adopted stable and uniform tunneling parameters, while the second shield utilized low total thrust, low shield speed, smaller cutterhead torque, and lower cutterhead rotation speed, achieving effective control of surface and structural settlement. Monitoring results showed that after tunneling, the grouting layer showed no significant defects, and surface settlement directly above tunnel crown and structural slab settlement were significantly lower than the control values specified in the standards, demonstrating the effectiveness of the optimized tunneling parameters and reinforcement measures. This study provided valuable experience for double-line shield tunneling in composite strata.</p>