Abstract: The Cangyuan Tunnel of Lanzhou-Chongqing Railway passes through the debris flow accumulation body with loose structure and high moisture content, and its minimum depth is only 14 m. The base of the tunnel has poor stability and low bearing capacity. Based on the comparison and analysis of the common methods for the tunnel base, this project is reinforced by the root piles. The mechanical behaviors of the tunnel during construction process and the treatment effects of base reinforcement are simulated by numerical experiments. The settlements of tunnel base after construction and the vibration dynamic response rules of the tunnel and the base with or without root piles are analyzed under the loading frequency vibrations of different train dynamic loading cases. Combined with the field monitoring data, the construction deformation control and basal reinforcement method for tunnels in debris flow are proposed, and they are available for the design and construction of similar projects.