Failure mode of shield excavation face using transparent soil

Abstract

The stability of the excavation face plays a critical role in the safety of shield tunnel construction, and the failure mode is one of the most important factors. By using transparent soil materials, it is possible to obtain a more real displacement field of the soil without disturbed. This paper used the transparent soil model tests and numerical simulation, two situations of the single tunnel and the crossing existing tunnel were performed to investigate failure mode of the excavation face. The test results indicated that the failure mode of single tunnel is a bulb-like shape with soil arching effect, and the failure mode of crossing existing tunnel is a wedge shape. In addition, comparing the two cases, the surface settlement of the crossing existing tunnel is significantly reduced. This means that the existing tunnels can weaken the surface settlement.