Study On The Track Deformation And Dynamic Response Under The Conditions Of Shield Tunnel Down-traversing The Ground Railway Traffic Line

In recent years, with the rapid development of urban rail transit, number of cases like tunnel excavation through existing line grows rapidly. The ground settlement caused by the excavation will lead to the deformation of the track structure, which inevitably effects the operation and safety of the whole line. Currently, shield excavation becomes an important method in the construction of city subway. The following factors cause the ground movement in shield excavation:shield diameter, shield depth, the property of soil and construction conditions, etc. In this paper, it has taken the earth pressure balance shield tunneling machine as an example, using integral analysis method. By the general-purpose finite element analysis software ABAQUS, it builds the whole model of soil, track bed,subgrade and the track. The process of shield excavation was simulated with the reasonable parameters. Following are the main research findings:(1) Comparing the basic rules of track structure deformation in the excavation process with different shied conditions which includes shied diameter, depth and one tunnel excavated in advance, it proposes some reasonable construction suggestion.(2) The vertical vehicle-track coupling model was built to analysis the impact on dynamic characteristics of the track and vehicle running behavior caused by the excavation static irregularity from the excavation. The mainly analysis objects are the vertical acceleration of rail and vehicle,the dynamic displacement of rail and the wheel-rail contact force. It also gives some operation suggestions.