Influence of Tunnel Excavation on the Stability of a Bedded Rock Slope: A Case Study on the Mountainous Area in Southern Anhui, China

Abstract

Tunnel excavation has a substantial effect on the stability of rock slopes. The influence of tunnel excavation on the deformation and mechanical characteristics of a bedded slope is investigated by analysing the cumulative displacement, stress, and strain of the slope using the finite-element method (FEM) and field monitoring method. The deformation characteristics of the surrounding rock of the tunnel and slope with a supporting structure were analysed using the FEM under the conditions of support or without support. The results show that the deformation characteristics of the slope are controlled by its discontinuities. The deformation of the slope is mainly concentrated in the area above the second discontinuity; in particular, the deformation above the first discontinuity is the largest. In addition, the deformation and mechanical characteristics of the support structure are analysed. The supporting structure has influence on the deformation of the slope, which reduces the cumulative displacement, stress and strain. The shear strains of the second and third discontinuities are greatly influenced by the supporting structure. The mechanical properties of the tunnel support structure are controlled by the first discontinuity, and a stress concentration occurs near the first discontinuity. Moreover, based on the combination of the numerical and field test results, the deformation of the rock slope is closely related to the distance from the slope surface. Tunnel excavation mainly has a significant impact on the deformation of surface slope within a certain range, especially the slope deformation within the range of 4 m, which is the largest.