Analytical wave function method for modelling a twin tunnel embedded in a saturated poroelastic full-space

Journal article, 2019

An analytical wave function method for the calculation of vibrations from two tunnels embedded in a saturated poroelastic full-space due to a harmonic point load is given, in which the multiple scattering between twin tunnels is considered exactly. The two tunnels made of viscoelastic material are modelled as two hollow cylinders. The soil surrounding two tunnels is water-saturated, and modelled as a two-phase poroelastic material. The wave field in the full-space with two circular cavities is a superposition of outgoing waves outside the two cavity surfaces. As there is water in the soil, the hydraulic boundary at the tunnel-soil interface is necessary when solving this multi-scattering problem. The translation properties of outgoing waves are adopted to apply boundary conditions described in two sets of cylindrical coordinates. The proposed analytical method for modelling twin tunnels provides a new tool to study the interaction between twin tunnels buried in a poroelastic medium. Some typical numerical results are given to illustrate the influence of the soil permeability and the permeability of the tunnel-soil interface on the displacement and pore pressure responses. In addition, the results for a single tunnel are compared to those of a twin tunnel with various separation distances and angles.