Research On The Safety Influence Of Chongqing Liangjiangqiao Tunnel And The Connecting Line Tunnel To The Existing UMT Tunnel

With the continuous expansion of urban system,urban traffic is more complex and more significant,which gives the great challenges to the utilization of underground space."To get the underground space" means that as an important urban public traffic mode,the function and number of the subways and the substations will be significantly enhanced,and this demand will inevitably lead to the influence of the tunnel to be constructed to the surrounding rock and the built structure.However,due to the multiple affecting factors,many underground engineering scholars have made an great effort on this problem by means of experiment test,theoretical analysis,numerical simulation,engineering case,the real phenomena are that the solutions are usually not in accordance with the engineering situation,or the newly constructed engineering can’t effectively ensure the security requirement to the near formation and the adjacent engineering,thus restrict the further development of the underground traffic construction.This paper is based on Chongqing Liangjiang bridge tunnel and interface project,the security research is carried out via numerical simulations by engineering analogy method to the project where is adjacent to the existing rail lines of No.1 and No.6 Tunnel.The conclusion can be drawn as follows: Firstly,the proper support design scheme should be ensured by the synthesis of the near geological conditions and the relationship between the newly built and the built ones.Secondly,choose the construction method suitable for the railway tunnel;and thirdly,take the proper measurement to protect the built rail tunnel in the procedure.Meanwhile,construct the contact model of the newly built tunnel and the built ones in the key sections to calculate the built load of the formation and the deadweight of the tunnel frame;furthermore,simulate the excavation process of the important sections to investigate the influence mechanism of the construction procedure to the adjacent formation settlement and the important structure,such as the vertical displacement of the secondary lining,the deformation and plastic zone of surrounding rock,supporting stress,bearing capacity of foundation,and the building foundation inclination and settlement.Finally,based on the above calculating results,the optimization evaluation has been made on the design and construction scheme.This method can be used for the adjacent problem analysis and the reference for the similar engineering,which has the favorable theoretical value and engineering meaning.