ANALYSIS ON THE AFTER-CONSTRUCTION STABILITY OF OPEN-CUT TUNNEL OF HIGH-SPEED RAILWAY UNDERPASSING EXISTING HIGHWAY

When the new railway tunnel undercrosses the existing highway, the crossing interaction becomes inevitable between different lines, it not only affects deformation of the tunnel and the pavement, but also affects the safety of the line. Therefore, it is vital to analyze the changes of tunnel structures and patterns of construction settlement. Based on the engineering that a new open-cut railway tunnel undercrossed the existing highway, for the intersection part, the soil deformations, deformations and the mechanical conditions of supporting structure and existing highway were studied by using MIDAS/GTS finite element software under the self-weight load and the lane load after the completion of the tunnel construction. The results showed that the maximum settlement took place in crown. The cross-range size and angle had a striking impact on the lining settlement, the probability of tensile failure occurred in hance on the inside of supporting structure is higher than that of the crown. It was found that the settlement of the intersection part of existing highway and crossing railway tunnel was less than the pavement on both sides for the shallow tunnel with the ratio of cover and span below 0.5. The tensile failure may occur at the junction of C30 reinforced concrete pavement and C20 plain concrete pavement and the structures should be strengthened.