Abstract: Because of the accidents, such as landslide, water (mud, sand) gushing, happening easily when the starting and arriving of shield construction of subway tunnel, it was the most important problem to optimize the reinforcing design of stratum in the area. Combine with actual reinforcement in the starting stratum of the Shumuling shield tunnel of the Changsha-Zhuzhou-Xiangtan inter-city railway, the longitudinal reinforcement range of the end soil mass under different safety factors was calculated using elastic plate theory and the strength and stability of the reinforcement soil mass were checked using strength theory and slipper theory firstly; meanwhile, the transverse reinforcement range of the end soil mass of shallow shield was ensured using Terzaghi’s theory of rock pressure. The influence of the surrounding environments by shield-driven in the different reinforcement range stratum was analyzed using FLAC3D, according to the relevant monitoring specifications and design documents, the optimized reinforcement range of the end soil mass was ensured from the point of view of economy and stability, and the results were used in the actual engineering. Final, comparison with the data of numerical simulation and actual monitoring of optimal design scheme, both of the data matched well. The optimal design scheme was feasible. The research can provide some reference for the similar engineering.

Key words: EPB shield, starting stratum, reinforcement optimization, safety factor, numerical simulation