Effect of earthquake excitation on circular tunnels: Numerical and experimental study

Abstract

This paper studies the behaviour of circular tunnel subjected to dynamic excitation. Tunnels with three different diameters were selected to perform the shake table test at three different covers. The dry sandy soil was used for testing. The mechanical properties like Young’s modulus and shear modulus of sand was calculated from bender element test. The soil–tunnel interface coefficient was calculated from the direct shear test. The soil pressure generated due to dynamic loading were measured by soil pressure transducers. The actual motion of shake table was captured by hand-held vibration analyser. The tunnel was placed parallel and perpendicular to the direction of shaking. The three-dimensional finite-element model was developed for tunnel with both the orientations. The tunnel was assumed to be elastic. Dry sand was assumed to follow non-linear elasto-plastic material using Mohr–Coulomb failure criterion with non-associated flow rule. The results obtained from numerical analysis are compared with experimental results and are expressed in the form of peak dynamic stresses. The time history and fast Fourier transform results of dynamic stresses are also compared. It shows reasonable agreement with both values. Finally, the seismic design guidelines for tunnel are suggested.