Study on the Dynamic Response and Reasonable Design Parameters on Bottom of Tunnel Structure under Heavy Loading

In this paper, a coupled numerical model of heavy-haul railway tunnel structure and surrounding rock was established, based on the theory of dynamic finite element. Train load in the model was simulated by excitation function. The paper analyze the influence of different design parameters, in terms of rise-span ratio and thickness of packing layer and invert, on the characteristics of dynamic response in heavy-haul railway tunnel structure. The result showed that dynamic response of whole bottom structure of heavy-haul railway tunnel is much more significant than that of normal railway tunnel, which would bring about more disadvantageous consequences to structural stability of tunnel. The peak value of different mechanical index as well as its position have been found through research. Further research studied reasonable planning parameters of bottom structure in double track railway tunnel under the heavy load by setting typical condition. The study showed reasonable value of rise-span ratio and thickness of packing layer and invert is 1/10~1/11, 1.2~1.3m and 40~50cm respectively, which could reduce dynamic response and improve stress states of double track railway tunnel under the heavy load.