Numerical Simulation And Stability Analysis Of Dachuan Tunnel Construction

Combining trait of tunnel researching and present conditoions of constructing interior and aboard, the numerical simulation and stability analysis of Dachuan tunnel constucting were made by FEM software ANSYS, based on the design and constructing of Dachuan tunnel in Shiliang highway in Shiyan Hubei province. Stability of adjacent rocks, internal force, strain and displacement of tunnel support in different adjacent rocks, constructing method and stage of construction procedure are researched according to the result of simulation.Adjacent rocks, shotconcrete, bolt and second lining are simulated by plane42, beam3, link1 and beam3. Utilizing the DP (Drucker—Prager) surrender criterion, tunnel model in different adjacent rocks, constructing method and stage of construction procedure are built. And the same time, simply introduce method of excavate and unload. In carries on to the tunnel excavates and supports and protects the process in the simulation ANSYS simulates the material elimination and increases through kills and activation with the unit.The paper considered the deadweight and neglect structural stree simulated stress of adjacent rocks, and internal force of support in different situation. The result showed that the biggest bending moment value and the biggest shear strength value is at spring of arch, the biggest axle strength value is under middle of arch.ForⅢlevel adjacent rock, under full section excavate, it is little influence on stress of adjacent rock whether set inverted arch or not, but it will decrease bending moment at the spring and tension stress at the top. By step excavating, stress of adjacent rock is small when set inerted arch.ForⅣandⅤlevel adjacent rock, both be set inerted arch, circle excavation the stree of adjacent rock is more unform than pedestal sit excavation. ForⅣlevel adjacent rock, whether set inerted arch stress of adjacent rock is of little influence, but it can decrease internal force of second lining at the spring. ForⅤlevel adjacent rock, setting inerted arch can decrease compression stress and at spring and equivalent stress properly, as well as bending moment and shear force at spring.Numerical simulation of Dachuan tunnel indicate that no matter which form of construction work is, the major displacement is at the top (tunnel, adjacent rock).ForⅢlevel adjacent rock, whether set inerted arch under step excavate or full section excavate is of little influence for displacement, as wll asⅣlevel adjacent rock under step excavate. But it will reduce the displacement of second lining when set inerted arch.ForⅤlevel adjacent rock, setting inerted arch can reduce the displacement of adjacent rock under step excavate, especially the horizontal. And it will reduce the displacement of second lining when set inerted arch.ForⅣandⅤlevel adjacent rock, both be set inerted arch, circle excavation the dislacement is less than pedestal sit excavation.Ultilizing numerical calculation to solve rock-soil engineering is principal basis of engineering design and stability analysis for constructing. But owing to lots of indeterminate underground, to ensure the safety of tunnel construction and application, information back coupling in excution must be emphasized. And, utilize the information adjust the tunnel constructing.