Tunnel-soil-pile interaction in the prediction of vibration from underground railways: validation of the sub-models

This paper proposes a method for calculating the vibration levels from an underground tunnel, adjacent to a piled-foundation, embedded in a homogeneous half-space on the basis of strong coupling. The method relies on superposing the vibration field generated by the tunnel with that generated by the piled-foundation. The soil in this paper is modelled utilising the boundary element method, while the tunnel is modelled using thin-shell theory and the piled-foundation is modelled by adopting the elastic bar and Euler beam theories. Only the results of the sub-models (tunnel and piled-foundation) are presented herein and compared with previous work in the literature. The current tunnel model is contrasted to the well-known PiP model whereas the piled-foundation model is validated against a previous boundary element model. The comparisons reveal good agreement between the results of the current model and those of the previous models. The robustness of the current model has been highlighted by examining the responses of the tunnel at points on the free surface when it is subject to a point harmonic load at its invert. The responses of the piled-foundation to horizontal and vertical point loads on the pile-head are also investigated, in addition to the displacement field on the free surface due to a vertical point load.