<p>Layered rock masses represent complex geological formations characterized by pronounced anisotropy in strength. This study monitors stress/deformation during construction to summarize layered rock mass deformation and support stress characteristics based on Yunwushan Tunnel. Shale shows greater vault settlement and asymmetric support deformation than sandstone. The excavation was optimized by establishing a numerical model, analyzing the advanced support effect, and redesigning the anchor rod to control the asymmetric large deformation. The results show that: 1) It is effective to set a transition section before the sudden change of rock mass, and the optimal distance for setting the transition section is 6 m. 2) The implementation of advance small pipe support has been shown to effectively mitigate settlement in the tunnel arch, whereas anchor bolt support is effective in controlling the horizontal convergence of the surrounding rock. 3) Adjusting the angle of the anchor bolt is a cost-effective reinforcement method when facing asymmetric deformation. 4) It is recommended to flexibly adjust the angle of the anchor bolts and increase the advance small pipe support in mountain tunnel projects under the transformation of rock strata. These outcomes may serve as a valuable reference for the design and construction of similar engineering projects.</p>