Study On Mechanical Behavior Of Segments At The Intersection Of Super Large Diameter Shield Tunnel And Connecting Passage

Because of its special safety significance,the communication channel is often an extremely important part in the design of urban underground rail transit double-line tunnels.When a tunnel disaster occurs,it is an important life channel for evacuation and fire rescue.The construction of the connecting passage of the super-large diameter shield tunnel is very risky.A slight carelessness may cause major accidents such as stratum instability,soil and water influx,and the opening construction will also make the shield tunnel structure more unfavorable and cause the overall deformation of the structure And security control has a huge impact.In view of this,this article relies on the East Sixth Ring Road Reconstruction Project,aiming at the complex risks of structural forces faced by the construction of the connecting passage of the super large-diameter shield tunnel,using literature research,ABAQUS numerical simulation analysis and geotechnical centrifugal model test methods to conduct research,mainly The research work is as follows:(1)The existing domestic and foreign connection channel construction engineering examples were investigated,and the connection channel construction method,opening shape and size,stratum reinforcement plan,and main tunnel segment lining types were summarized and compared.(2)Through numerical simulation analysis,the influence laws of circular opening and rectangular opening on the force and deformation of the main tunnel segment are respectively explored.Studies have shown that the deformation of the main structure of the circular opening is smaller than that of the rectangular opening,but the stress concentration of the structure at the opening is more obvious,and the tensile and compressive stresses are higher.(3)The control effects of different stratum reinforcement ranges under different opening shapes on the stress and deformation of the main tunnel structure are compared,which provides a basis for the reasonable selection of stratum reinforcement ranges.Studies have shown that the increase in the reinforcement range has a better control effect on structural deformation and a more reasonable stress state.(4)The control effects of different special lining ring types under different opening shapes on the force and deformation of the main tunnel structure are compared,which provides a reference for the selection of the special lining ring of the main tunnel during the construction of the shield tunnel as the connecting passage.Studies have shown that it is more reasonable to use six steel plate-fiber reinforced composite tubes for circular openings,and it is more reasonable to use four steel plate composite tubes for rectangular openings.(5)With reference to the construction plan of the Hong Kong Tuen Mun Tunnel connecting passage project,numerical simulation was used to analyze the influence of different thrust and torque load combinations on the force and deformation of the main tunnel segment before and after the mechanical construction broke the segment.The study found that the segment The influence of reasoning and torque before breaking is extremely small.After the segment is broken,the force and deformation of the main tunnel structure are smaller as the thrust increases.At the same time,the influence of different frost heave loads on the force and deformation of the structure under the rectangular opening condition is analyzed.(6)On the basis of the numerical simulation analysis results under different opening forms,with the help of the TK-C500 geotechnical centrifuge of Tianjin Water Transport Engineering Research Institute of the Ministry of Transport,the centrifugal model test was carried out with a geometric similarity ratio of 1:50,and the comparison of different opening shapes was explored.The law of the influence of the main tunnel structure on the force,the study found that the tensile stress on the outer side of the top of the opening and the compressive stress on the inner side of the arch waist regardless of the rectangular opening or the circular opening exceed the design value of C60 concrete strength,so it can be considered in actual engineering The split ring adopts the steel-concrete composite segment type,which verifies the numerical simulation results.