Research On The Impact Of Deformation And Destruction Of The Diversion Tunnel Structure Under Railway Operating

With the rapid growth of China's national economy, the demand for infrastructure construction is increasing, especially land transport and underground tunnel and other underground construction projects is developed the most rapid, so the inevitable situation will be occured that railway through the existing tunnel. This situation will affect security and stability of the existing tunnel.This thesis be the backgroud of a diversion tunnel, using of explicit finite difference program-FLAC3D on calculate and analyze the stability of tunnel surrounding rock structure.First of all, we do the force analysis for tunnel section based on the understanding of geological situation of construction. Moreover simplified train vibration load according to the characteristics of train vibration. Then determine the calculating parameters and conditions, and select the appropriate boundary conditions for the calculation model established.Respectively, research on the deformation damage of diversion tunnel for the three operating conditions defore and the six operating conditions after the construction. Comparative research obtained that train operations on the surrounding rock structure of existing tunnel in the impact of deformation and failure.Simulation calculation in this thesis, consider the variation and combination of various factors before and after the railway construction, especially consider that the running and braking of train, the operation and maintenance of hydropower station, and nine combined conditions constructed from these factors.According to strength reduction finite difference method by FLAC3D, for these nine operating conditions of three typical profiles of tunnel section in the numerical simulations. In connection with different situations of three profiles, simulated the maximum tensile stress diagram, maximum compressive stress diagram, displacement cloud,and distribution of plastic zones of nine operating conditions.On the calculated data are analyzed and discussed, we can obtained the relationships between the maximum tensile stress, maximum compressive stress, andmaximum displacement at department of tunnel structure.Conclusion of research conclude that predict the tunnel appears Some degree of cracks in some operating conditions.The necessity for crack repairing and the assurance for tunnel running are both have directive significance. And propose several remedial programs,guiding significance on the design for tunnel structure and railway crossing tunnel.