Effect Research of Excavation Scheme in the Close Distance Undercrossing Construction of Shield Double Tunnels Beneath Existing Stations
Due to the networked operation of the subway,the problem of new tunnel projects crossing existing subway facilities has emerged,which has brought stricter requirements for the construction of new subways.Because of various factors such as construction environment constraints,shield tunneling construction in double tunnel subways often adopts opposite or same direction excavation methods.In this study,numerical analysis of tunnel construction operations in a certain section of Beijing Metro Line 8 was carried out using finite element software,and on-site monitoring and measurement data was combined to compare the effects of different excavation spacing and excavation sequence on the structural deformation of existing stations.The results show that:(1)when crossing beneath the existing station at a close distance,there is not much difference in the settlement deformation values of the existing station under the methods of excavating in opposite directions and excavating in the same direction.The excavation order can be selected according to the actual environment and conditions.(2)The smaller the distance between the left and right lines,the more significant the impact of shield tunneling on the settlement of the existing station structure when excavating double tunnels in the same direction;(3)If the construction period is tight and the excavation work needs to be carried out for both tunnels simultaneously,it should maintain an interval of no less than 30 rings between the later tunnel and the prior tunnel.Additionally,settlement control measures should be implemented for the tunnel excavated later.
NETL
NSTL
万方数据
