A subway line adjacent to a seven-story building in Zhengzhou City was taken as the engineering background to investigate vibration isolation measures. A three-dimensional numerical model encompassing the vehicle, track, tunnel, soil, and building was established using the finite element software ABAQUS. The accuracy of the numerical model and the rationality of the assumptions were validated by comparing simulated vibration data with field measurements. The research first examined the influence of barrier thickness and depth on the isolation effectiveness of conventional open trenches and concrete continuous walls. By integrating the advantages of these two traditional methods, two novel barrier types were proposed: concrete hollow walls and composite rigid-flexible concrete walls. A comparative analysis of the vibration isolation performance of all four barrier types reveals that isolation effectiveness increases with depth, while barrier thickness has a negligible effect. Considering project cost and isolation performance, the optimal depth for all barrier types should extend to the burial depth of the tunnel bottom. The concrete hollow wall provides a marginal improvement of 0.8 dB over the concrete continuous wall. In contrast, the composite rigid-flexible concrete wall shows a more substantial enhancement of 2.7 dB, achieving an isolation performance close to that of an open trench. Considering factors such as subway tunnel burial depth, maintenance costs, the durability of open trenches, and the performance of the four barrier types, the composite rigid-flexible concrete wall is recommended for vibration protection of buildings near subway lines. The outcomes of this study serve as a reference for vibration assessment and the design of isolation and mitigation measures in domestic subway projects.