Shaking table test on a tunnel-group metro station in rock site under harmonic excitation

Abstract

A tunnel-group metro station built in rock site is composed of a group of tunnels. Different tunnels and their interconnections can show inconsistent responses during an earthquake. This study investigates the dynamic responses of such a metro station in a rock site, by shaking table tests. The lining structures of each tunnel and surrounding rock are modeled based on the similitude law; foam concrete and gypsum are used to model the ground-structure system, keeping relative stiffness consistent with that of the prototype. A series of harmonic waves are employed as excitations, input along the transverse and longitudinal direction of the shaking table. The discrepant responses caused by the structural irregularities are revealed by measurement of acceleration and strain of the model. Site characteristics are identified by the transfer function method in white noise cases. The test results show that the acceleration response and strain response of the structure are controlled by the ground. In particular, the acceleration amplification effect at the opening section of the station hall is more significant than that at the standard section under transverse excitation; the amplification effect of the structural opening is insignificant under longitudinal excitation.