The excavation area of super-large section tunnels (with a cross-sectional area greater than 100 m²) is large, leading to significant disturbance of the surrounding rock. As a result, advanced support is often required to ensure the safety of tunnel construction. Pipe shed grouting reinforcement is a widely adopted method for advanced tunnel support, primarily aimed at controlling the stress and deformation of the surrounding rock by creating a grouting reinforcement ring above the tunnel's surrounding rock. In numerical simulation calculations, the thickness of the grouting reinforcement ring plays a critical role in the accuracy of the results. An optimization of the traditional calculation formula was proposed, considering the impact of the pipe roof extrapolation angle and lap length on the thickness of the grouting reinforcement ring, based on a practical tunnel project. FLAC3D was employed to perform a comparative analysis between two calculation conditions: grouting reinforcement with and without a pipe roof. The results show the following.① The optimized formula for determining the thickness of the grouting reinforcement ring is influenced by five parameters: the pipe roof extrapolation angle, grouting diffusion radius, pipe roof length, longitudinal spacing, and circumferential spacing of the pipe roof. Numerical simulations based on the optimized formula yield results that are more consistent with field monitoring data, thereby improving the accuracy of the calculations. ② When advanced pipe shed grouting support is applied, the settlement displacement at the tunnel vault is reduced to 12.65 mm, representing a decrease of 31.06% compared to the condition without advanced support. ③ The pipe roof grouting support leads to a reduction of 20.72% in the maximum vertical compressive stress of the surrounding rock, a reduction of 44.68% in the maximum vertical tensile stress, a 15.87% decrease in the maximum principal compressive stress of the initial support structure, and a 23.81% reduction in the maximum principal tensile stress. ④The maximum surface settlement with pipe shed grouting reinforcement is found to be 8.95 mm, which is 24.25% lower than that observed in the absence of such reinforcement. ⑤ The grouting reinforcement effect of the pipe shed is positively correlated with the slurry diffusion radius, the outer angle of the pipe shed, and the length of the pipe shed, while it is negatively correlated with the longitudinal spacing and circumferential spacing of the pipe shed. Among these parameters, the slurry diffusion radius exerts the most significant influence, whereas the outer angle of the pipe shed has the least effect.