An experimental study of ground-borne vibration from shield tunnels

Along with the ongoing development of urban railways, ground-borne vibration from trains has received considerable attention in the past decades. Various research studies have been conducted to study this problem. In order to simplify the problem for analysis, it us commonly assumed that tunnels have a uniform lining; however in reality this usually not the case. With the development of shield tunnelling, precast segmental linings are widely used. The existence of the joints between tunnel segments can significantly affect the dynamic behaviour of the tunnel. In this paper, results from a series of physical model experiments are described to explore the dynamic characteristics of segmental tunnel linings. Three different tunnel lining models were tested: uniform, straight-jointed segments, and stagger-jointed segments. In the experiments, vibration excitation was applied to the model tunnel invert by a shaker. The tunnel and soil responses at different locations were measured by accelerometers during the tests. Comparison of the results from the different tunnel lining models shows that the segment joints have a considerable effect on the dynamic behaviour of the tunnel lining. Due to the effects of interface damping at the segment joints, the response of both types of segmental linings was found to be significantly smaller than the response of the uniform tunnel lining. The experimental results also show that the segment joints have less impact on the soil response and mainly affect the soil response in the frequency range below 80 Hz.