Study on the Deformation Characteristics of Different Excavation Methods for Class V Perimeter Rock Tunnels

Abstract

Taking a water conservancy project water transfer tunnel as an example, FLAC3D finite element simulation software was used to simulate the excavation and support, and the displacement and distribution of the plastic zone of the tunnel perimeter rock were taken as the analytical indexes, and the simulation of the three excavation methods, namely, the full section method, the half section method and the CD method, was carried out to compare, and to study the characteristics of the deformation of the perimeter rock of the different methods of excavation. The simulation results show that: ① the vertical deformation of the three excavation methods all show that the bottom bulge is larger than the settlement of the vault; ② the full-face method is easy to produce shear damage at the vault, the step method is easy to produce shear damage at the waist of the tunnel, and there is no obvious damage characteristics of the CD method; ③ the CD diaphragm wall method is able to control the vertical deformation of the surrounding rock effectively, and the horizontal displacement will be increased, and joint support measures should be taken at the waist of the tunnel to strengthen the support.