The Data Simulation of the Shallow Underground Tunnel Excavation in Soft Rock

The study of the impact to the above ground structure as a result of the shallow underground tunnel excavation in soft rock is relatively uncommon compared to the numbers of actual tunnel construction by adoption of this excavation technique. To explore a new calculation model for the above impact, the FLAC is applied on the typical cross section of tunnel selected from actual construction case to set up the two dimensional tunnel force model. The model is further utilized as a base to evaluate the structural implication under different staging tunnel excavation. The result concluded that the initial deformation of the shallow underground tunnel would be reduced by adopting immediate bracing and short interval excavation techniques. In addition, emphasis should be placed on the settlement control of soil at the tunnel apex and the upheaval of soil at the tunnel base during tunnel construction.