The gully is always characterized by poor rock and complicated geology conditions, and tunnelling in this situation can bring a series of difficulties such as extreme deformation or even collapse. In this paper, the in-situ measurements and finite element method (FEM) are adopted to characterize the deformation behaviors of the rock mass of a shallow loess tunnel passing through a U-shape gully. The measurement results indicated that timely closure of the invert arch can effectively control the horizontal convergence and vault settlement of the rock mass. More time is required for the purpose of stabilizing rock mass at gully slope compared with the other locations, and the deformation exhibits a significant longitudinal difference along the tunnel extension. The extrusion deformation of the tunnel face increases gradually as the face advance, so it is suggested to adopt effective reinforcement method to ensure the face stabilization. In addition, the risks of the re-shape work should be noticed considering a significant tunnel bottom uplift was observed. It is expected this study can provide guidance and reference during the construction of the similar projects.

CICTP