Study on the Influence of Cycle Footage on the Dynamic Stability of Tunnel Portal Section Construction
During the construction process,it is important to study the interaction and failure mechanism between tunnel and surrounding rock to maintain the stability of the structure.The calculation model of Luohanshan tunnel in Fuzhou,Fujian Province was established by finite element software.The displacement and plastic zone development of surrounding rock and structure were discussed.Based on the strength reduction method,the dynamic safety factor changes of the tunnel model considering the front section and different advance per round were analyzed.Through the analysis,it is found that the main cause of failure is the development of the surrounding rock of the tunnel en-trance and the plastic zone of the slope.After the connection of the plastic zone,the slope appears to be unstable,and then the load and deformation are transferred to the tunnel structure;The strength reduction method is used to obtain the safety factor under different cyclic penetration,the smaller the cyclic penetration,the higher the slope stability of tunnel entrance section.The research results can provide theoretical basis for the construction stability estimation and instability prediction in tunnel entrance section.
tunnelentrance sectionadvance per roundstabilitystrength reduction methodsafety factor
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