| The Malazhai tunnel of Shanghai-Kunming railway goes through a breccias rock stratum with developed karst cave, rich groundwater and abundant clay minerals, which has great difficulties and risks because of adverse slope construction, big excavation section, large deformation during construction and poor stability of basement. Numerical simulation applies to anchored effect in the large pipe shed and small duct grouting as comprehensive advance support, arch foot longitudinal beam reinforcement and the middle bench with temporary inverted arch by using FLAC3 D software, and then, according to the displacement around the tunnel, tunnel face extrusion deformation and supporting structure stress analysis to select the tunnel reinforcement measures; based on this, the paper analyses the post-construction settlement and vibration of the basement in response of dynamic loading of train under different excitation frequencies and whether there is pile-raft foundation. The results indicate that the maximum settlement and vibration velocity of tunnel basement can meet the requirements of long-term stability after taking comprehensive reinforced measures and pile-raft foundation, which can provide protection for the safety of the latter operations of the tunnel. The conclusion can provide useful reference for the design, construction and research of similar tunnels. |
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