Main insights from 2D/3D poroelastic analysis of tunnel excavation in low permeability anisotropic ground

Pore pressure evolution induced by tunnel excavation in low permeability anisotropic ground is investigated by means of a fully coupled hydro-mechanical finite element simulation. The goal is to explore the main trends of the pore pressure evolution on the basis of a poroelastic analysis, taking into account: on the one hand, the influence of excavation and face advance; on the other hand, the inherent anisotropy of the material. It is shown that overpressures can be induced before the passage of the face, depending on: the consolidation time of the rock, the rate of excavation and the degree of anisotropy of both the material and the initial stress state. Finally, a discussion about pore pressure evolution at tunnel wall is presented. An analysis is performed in order to propose a pore pressure release rate at the tunnel wall for 2D models.

Automated summary

The evolution of pore pressure induced by tunnel excavation in low permeability anisotropic ground was investigated using a fully coupled hydro-mechanical finite element simulation. The study found that overpressures can be induced before the passage of the face, depending on factors such as rock consolidation time, excavation rate, and the degree of anisotropy in the material and initial stress state. Discussions on pore pressure evolution at the tunnel wall and proposing a pore pressure release rate for 2D models were also presented.