Mechanical Property Research Of Shallow-Buried Undercut Loess Subway Tunnel

To the lack of research on mechanical property in urban subway of shallow loess tunnel construction method in Xi'an, this article investigated the weight bearing about surrounding rock and support system of shallow loess tunnel,by indoor model test, field experiment, numerical simulation.1, It was analysised that surrounding rock stress distribution and its influence on the supporting structure in the construction process of shallow loess tunnel through the model test; In the damage test on tunnel lining, deformation and destruction features were analysised;And the mechanical characteristics of rockbolts in supporting system was also analysised.2, Based on the NO.2 subway in xian, large-scale field experiment were carried out, especially the pressure between first lining and surrounding rock, Grille arch steel frame axial force, the pressure between first lining and second lining, the change of the concrete on second lining over time. Field experiment information were provided to the model test and simulation analysis.3, Founding a finite element model with MIDAS/GTS and according to different conditions, it was detected that the distributions of the surrounding rock stress,the bending moment and the axial force in lining. Comparing the results of model test, field experiment and numerical simulation,it aimed at lessening the error which came from the method and studying regularity to explain the results.The same time, this results can back to the shallow loess subway tunnel construction, it can effectively guide the loess region Subway Tunnel design and construction, thereby greatly reducing the accident.