Numerical modelling of vibrations from a Thalys high speed train in the Groene Hart tunnel

This paper presents a numerical study of vibrations due to a Thalys high speed train in the Groene Hart tunnel, which is part of the high speed link South between Amsterdam and Antwerp and the world's largest bored tunnel. A coupled periodic finite element-boundary element model is used to predict the free field response due to the passage of a Thalys high speed train in the Groene Hart tunnel. A subdomain formulation is used, where the track and the tunnel are modelled using a finite element method, while the soil is modelled as a layered half space using a boundary element method. The tunnel and the soil are assumed to he invariant in the longitudinal direction, but modelled as a periodic structure using the Floquet transformation. A general analytical formulation to compute the response of three-dimensional periodic media excited by moving loads is adopted. The Groene Hart area is marshy and completely saturated. The top soil consists of layers of peat and clay with a very low density and shear wave velocity. The numerical model allows to understand the effect of these soft layers on vibration levels, resulting in an amplification of the horizontal response and a large contribution of the quasi-static forces at high train speeds. Vibration levels are assessed using the Dutch SBR guideline. It is concluded that the operation of high speed railway traffic in the Groene Hart tunnel is not expected to Cause serious vibration problems. (C) 2009 Elsevier Ltd. All rights reserved.